JP7717023B2 - Work vehicles - Google Patents

Description

The present invention relates to a work vehicle with a forward/reverse operation device located near the driver's seat.

Work vehicles such as wheel loaders are equipped with a forward/reverse operation device in the cab for moving the vehicle forward, backward, and stopping, and the shape and location of the device vary depending on the vehicle's specifications. In some cases, multiple forward/reverse operation devices are installed in different locations within the cab. Furthermore, to prevent the operator from accidentally touching a forward/reverse operation device and accidentally operating it incorrectly, a switch may be provided that can switch the forward/reverse operation device between an enabled and disabled state.

For example, Patent Document 1 discloses a work machine equipped with a forward/reverse lever device (first forward/reverse operating device) located on the steering wheel side, a forward/reverse switch device (second forward/reverse operating device) located on the work implement lever side for operating the work implement, and a changeover switch that commands switching between an enabled state in which forward/reverse switching control is performed by the forward/reverse switch device and an disabled state in which forward/reverse switching control is not performed by the forward/reverse switch device.

In this work machine, forward/reverse switching control by the forward/reverse lever device is always active, while forward/reverse switching control by the forward/reverse switch device is only active when the selector switch indicates a switch to an active state for forward/reverse switching control by the forward/reverse switch device and the forward/reverse lever device is in neutral. This prevents the work machine from accidentally traveling due to the operator unintentionally operating the forward/reverse switch device.

Japanese Patent Application Laid-Open No. 2005-256408

However, in the work machine described in Patent Document 1, if the selector switch is erroneously operated while the machine is traveling to a position that indicates a disabled state in which forward/reverse switching control by the forward/reverse switch device is not performed, forward/reverse switching control by the forward/reverse switch device will be disabled. In this case, when the operator wants to switch between forward and reverse modes in an instant, operating the forward/reverse switch device located right next to them will not work, and the operator will not be able to switch between forward and reverse as intended.

The object of the present invention is to provide a work vehicle that can switch between forward and reverse travel as intended by the operator, even if the selector switch is erroneously operated while the vehicle is traveling.

In order to achieve the above object, the present invention provides a work vehicle including a first forward/reverse operation device and a second forward/reverse operation device that are provided in a driver's cab and that operate the forward and reverse movement of a vehicle body; a switching device that is provided in the driver's cab and that outputs, as switching signals, an enable command that puts the second forward/reverse operation device into an enable state and a disable command that puts it into an disable state; and a controller that controls the forward and reverse movement of the vehicle body based on the switching signal output from the switching device, a first operation signal output from the first forward/reverse operation device, and a second operation signal output from the second forward/reverse operation device, the work vehicle having a running condition detection device that detects the running condition of the vehicle body, and the controller determines whether the vehicle body is running or stopped based on the running condition detected by the running condition detection device, and when the switching signal output from the switching device is switched from the enable command to the disable command while the vehicle body is running, the controller holds the second forward/reverse operation device in the enabled state and controls the forward and reverse movement of the vehicle body based on the first operation signal output from the first forward/reverse operation device and the second operation signal output from the second forward/reverse operation device.

According to the present invention, even if the selector switch is erroneously operated while traveling, the vehicle can still be driven by switching between forward and reverse as intended by the operator. Other issues, configurations, and advantages will become clear from the description of the following embodiments.

1 is an external side view showing an example of the configuration of a wheel loader according to each embodiment of the present invention. FIG. 2 is a diagram showing an example of the configuration of the interior of a driver's cab according to the first embodiment, as viewed from the ceiling side. FIG. 2 is a functional block diagram showing functions of a controller according to the first embodiment. FIG. 10 is a diagram illustrating an example of a display on a monitor. 4 is a flowchart showing a flow of processing executed by a controller according to the first embodiment. 10 is a table showing the state of the vehicle body and the transition of the monitor display when the selector switch, the forward/reverse operation lever, and the forward/reverse operation switch are operated, respectively. FIG. 10 is a functional block diagram showing functions of a controller according to a second embodiment. 10 is a flowchart showing a flow of processing executed by a controller according to a second embodiment. FIG. 11 is a diagram showing an example of the configuration of the interior of a driver's cab according to the third embodiment, as viewed from the ceiling side. FIG. 10 is an enlarged view of the operating lever in FIG. 9 . 11 is a flowchart showing a flow of processing executed by a controller according to the third embodiment. FIG. 13 is a diagram showing an example of the configuration of the interior of a driver's cab according to the fourth embodiment, as viewed from the ceiling side. 10 is a flowchart showing a flow of processing executed by a controller according to the fourth embodiment.

The following describes a wheel loader, which performs loading and unloading operations such as digging up earth, sand, minerals, etc. and loading them into a destination such as a dump truck or hopper, as one type of work vehicle according to each embodiment of the present invention.

<Overall configuration of wheel loader 1>
First, the overall configuration of a wheel loader 1 will be described with reference to FIG.

Figure 1 is an external side view showing an example configuration of a wheel loader 1 according to each embodiment of the present invention.

The wheel loader 1 is an articulated work vehicle that is steered by bending the vehicle body near the center. Specifically, a front frame 1A, which forms the front part of the vehicle body, and a rear frame 1B, which forms the rear part of the vehicle body, are connected by a center joint 10 so that they can rotate freely left and right, and the front frame 1A bends left and right relative to the rear frame 1B. In the following explanation, the left side of the vehicle body facing forward will be referred to as the "left direction," and the right side of the operator will be referred to as the "right direction."

The vehicle body is provided with four wheels 11: two wheels 11 are front wheels 11A, located on both the left and right sides of the front frame 1A, and the remaining two wheels 11 are rear wheels 11B, located on both the left and right sides of the rear frame 1B. Of the four wheels 11, only the front wheel 11A and rear wheel 11B located on the left side are shown in Figure 1. There are no particular restrictions on the specific number of wheels 11 provided on the vehicle body.

A working device 2 for loading and unloading work is attached to the front of the front frame 1A. The working device 2 has a lift arm 21 attached to the front frame 1A so that it can rotate up and down, two lift arm cylinders 22 that drive the lift arm 21, a bucket 23 attached to the tip of the lift arm 21 so that it can rotate up and down, a bucket cylinder 24 that drives the bucket 23, and a bell crank 25 rotatably connected to the lift arm 21 and forming a link mechanism between the bucket 23 and the bucket cylinder 24.

The lift arm 21 rotates upward relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22 extend, and rotates downward relative to the front frame 1A when the rods 220 of the two lift arm cylinders 22 retract. Note that in Figure 1, only the lift arm cylinder 22 located on the left side of the two lift arm cylinders 22 is shown by a dashed line.

The bucket 23 rotates upward relative to the lift arm 21 when the rod 240 of the bucket cylinder 24 extends (tilt operation), and rotates downward relative to the lift arm 21 when the rod 240 of the bucket cylinder 24 retracts (dump operation). This allows the bucket 23 to scoop up loads such as soil or minerals and discharge (discharge) them at the loading destination. The bucket 23 can be replaced with various attachments, such as a blade, and the wheel loader 1 can perform various tasks such as snow removal and earth-raising in addition to loading operations using the bucket 23.

The rear frame 1B is provided with a cab 12 where the operator sits, a machinery room 13 that houses various devices necessary for driving the wheel loader 1, and a counterweight 14 that maintains balance with the work implement 2 to prevent the vehicle body from tipping over. On the rear frame 1B, the cab 12 is located at the front, the counterweight 14 at the rear, and the machinery room 13 between the cab 12 and the counterweight 14.

The travel of the wheel loader 1 is controlled by a torque converter-type travel drive device. The torque converter-type travel drive device includes an engine, a torque converter connected to the engine's output shaft, and a transmission connected to the torque converter's output shaft.

In torque converter-type driving control, when the operator first depresses the accelerator pedal located inside the cab 12, the engine rotates according to the amount of depression, and as the engine rotates, the input shaft of the torque converter (hereinafter referred to as "torque converter") connected to the engine's output shaft rotates. When the torque converter's input shaft rotates, the torque converter's output shaft rotates via the oil inside the torque converter, and the output torque from the torque converter is transmitted to each of the four wheels 11 after being speed-shifted by the transmission. This allows the wheel loader 1 to travel.

On the other hand, when stopping or slowing down the wheel loader 1, the operator depresses the brake pedal located inside the cab 12. The forward/reverse clutch of the transmission is controlled according to the amount of depression of the brake pedal, and the transmission of driving force to the four wheels 11 is cut off. This causes the wheel loader 1 to stop or slow down.

Note that the travel drive system of the wheel loader 1 does not necessarily have to be a torque converter type, and may also be another drive system, such as an HST (hydraulic static transmission) type.

First Embodiment
Next, a first embodiment of the present invention will be described with reference to FIGS.

(Internal configuration of the operator's cab 12)
First, the internal configuration of the operator's cab 12 will be described with reference to FIG.

Figure 2 shows an example of the interior configuration of the driver's cab 12 according to the first embodiment, as seen from the ceiling side.

Inside the cab 12, there is a centrally located driver's seat 31, a handle 32 located in front of the driver's seat 31 for switching the vehicle's left/right traveling direction, a support column 33 extending upward from the floor and supporting the handle 32, a forward/reverse operation lever 34A protruding to the left from the support column 33 as a first forward/reverse operation device for switching the vehicle's forward/reverse traveling direction, a monitor 35 as a display device for displaying the vehicle's traveling status, etc., and a first work operation lever 36A and a second work operation lever 36B for operating the work equipment 2.

The steering wheel 32 is one aspect of a steering operation device. The vehicle turns left when the operator turns the steering wheel 32 left (counterclockwise), and turns right when the operator turns the steering wheel 32 right (clockwise).

The forward/reverse operation lever 34A has a forward position F, which moves the vehicle body forward, a reverse position R, which moves the vehicle body backward, and a neutral position N, which cuts off the driving force to the four wheels 11. For example, as shown in Figure 2, the forward position F, reverse position R, and neutral position N are arranged in this order from the driver's seat 31 side: reverse position R, neutral position N, forward position F.

The monitor 35 is mounted in the center of the front console 37, which is installed in front of the handlebars 32. Various switches and buttons are attached to the left and right sides of the monitor 35.

The first work operation lever 36A and the second work operation lever 36B are both single-axis levers that can be operated along the fore-and-aft direction of the cab 12, and are attached side by side in the left-right direction at the front of the side console 38 located to the right of the driver's seat 31. When the operator tilts the first work operation lever 36A located on the left side (driver's seat 31 side) in the fore-and-aft direction, the bucket 23 moves up and down relative to the lift arm 21. On the other hand, when the operator tilts the second work operation lever 36B located on the right side in the fore-and-aft direction, the lift arm 21 moves up and down relative to the front frame 1A.

In addition to the first work operation lever 36A and the second work operation lever 36B, the side console 38 is provided with a forward/reverse operation switch 34B as a second forward/reverse operation device for switching the forward/reverse direction of the vehicle body, a switch unit 390 including a changeover switch 39 as a switching device for switching the forward/reverse operation switch 34B between an enabled state and an disabled state, and a right armrest 31R for supporting the operator's right arm.

Like the forward/reverse operation lever 34A, the forward/reverse operation switch 34B has a forward position F, which moves the vehicle forward, a reverse position R, which moves the vehicle backward, and a neutral position N, which cuts off the driving force to the four wheels 11. In other words, in this embodiment, two different forward/reverse operation devices (a first forward/reverse operation device and a second forward/reverse operation device) are provided inside the cab 12, allowing the operator to use either the forward/reverse operation lever 34A or the forward/reverse operation switch 34B depending on their preference and the situation. The control states of the forward/reverse operation lever 34A and the forward/reverse operation switch 34B are displayed on the monitor 35.

The forward/reverse operation switch 34B is located to the right of the first work operation lever 36A and the second work operation lever 36B. The first work operation lever 36A, the second work operation lever 36B, and the forward/reverse operation switch 34B are located on the side console 38 in front of the right armrest 31R, allowing the operator to operate the first work operation lever 36A, the second work operation lever 36B, and the forward/reverse operation switch 34B while resting their right arm on the right armrest 31R.

As such, the forward/reverse operation switch 34B is located very close to the operator, making it easy to operate. However, there is a risk that the operator may accidentally touch it when operating the first work operation lever 36A or the second work operation lever 36B. On the other hand, when the operator wants to touch the forward/reverse operation lever 34A, they must extend their hand forward. Therefore, the forward/reverse operation switch 34B is more susceptible to accidental operation than the forward/reverse operation lever 34A.

Therefore, by providing a changeover switch 39 inside the driver's cab 12 (in this embodiment, on the side console 38), erroneous operation of the forward/reverse operation switch 34B is prevented. This changeover switch 39 outputs a switching signal to the controller 5 (described below) that either activates the forward/reverse operation switch 34B or deactivates it.

The forward/reverse operation lever 34A, forward/reverse operation switch 34B, and changeover switch 39 are each electrically connected to the controller 5. The controller 5 controls the forward/reverse movement of the vehicle body based on the first operation signal output from the forward/reverse operation lever 34A, the second operation signal output from the forward/reverse operation switch 34B, and the changeover signal output from the changeover switch 39.

(Functional configuration of controller 5)
Next, the functional configuration of the controller 5 will be described with reference to FIG.

Figure 3 is a functional block diagram showing the functions of the controller 5 according to the first embodiment.

The controller 5 is composed of a CPU, RAM, ROM, HDD, input I/F, and output I/F, all connected to one another via a bus. Various operating devices, such as the forward/reverse operation lever 34A, forward/reverse operation switch 34B, and selector switch 39, as well as sensors such as a vehicle speed sensor 40 that serves as a driving condition detection device for detecting the vehicle's driving condition, are connected to the input I/F. The forward solenoid valve 41 that controls the forward clutch, the reverse solenoid valve 42 that controls the reverse clutch, and the monitor 35 are connected to the output I/F.

In this hardware configuration, the CPU reads a control program (software) stored on a recording medium such as a ROM, HDD, or optical disk, expands it on RAM, and executes the expanded control program, causing the control program and hardware to work together to realize the functions of the controller 5.

In this embodiment, the controller 5 is described as a computer configured by a combination of software and hardware, but this is not limiting. For example, as an example of another computer configuration, an integrated circuit that realizes the functions of a control program executed on the wheel loader 1 side may be used.

The controller 5 includes a data acquisition unit 51, a switching determination unit 52, a vehicle body state determination unit 53, a memory unit 53A, a valid/invalid determination unit 54, a traveling direction determination unit 55, and a signal output unit 56.

The data acquisition unit 51 acquires the first operation signal output from the forward/reverse operation lever 34A, the second operation signal output from the forward/reverse operation switch 34B, the switching signal output from the changeover switch 39, and data related to vehicle speed output from the vehicle speed sensor 40.

The switching determination unit 52 determines whether the switching signal acquired by the data acquisition unit 51 is a valid command or an invalid command. The switching determination unit 52 also determines whether the switching signal output from the changeover switch 39 has been switched from one command to another (from a valid command to an invalid command, or from an invalid command to a valid command).

When the switching determination unit 52 determines that the switching signal output from the changeover switch 39 has been switched from an active command to an inactive command, the vehicle body state determination unit 53 determines whether the vehicle body is moving or stopped based on the vehicle speed V acquired by the data acquisition unit 51. Specifically, the vehicle body state determination unit 53 compares the vehicle speed V acquired by the data acquisition unit 51 with a predetermined threshold value Vth.

The "predetermined threshold value Vth" corresponds to the vehicle speed when the wheel loader 1 (vehicle body) is stopped, and is a value that takes into account not only 0 km/h but also the error range of the vehicle speed sensor 40, and is stored in advance in the memory unit 53A.

When the switching determination unit 52 determines that the switching signal output from the switching switch 39 has been switched from an invalid command to an valid command, the valid/invalid determination unit 54 validates the second operation signal from the forward/reverse operation switch 34B acquired by the data acquisition unit 51 (enables the forward/reverse operation switch 34B).

Furthermore, when the switching determination unit 52 determines that the switching signal output from the changeover switch 39 has been switched from a valid command to an invalid command, and the vehicle body state determination unit 53 determines that the vehicle speed V is greater than a predetermined threshold value Vth (V > Vth), i.e., the vehicle body is moving, the valid/invalid determination unit 54 enables the second operation signal from the forward/reverse operation switch 34B (maintains the valid state of the forward/reverse operation switch 34B) if the current second operation signal is valid.

Furthermore, if the switching determination unit 52 determines that the switching signal output from the changeover switch 39 is an invalid command, and the vehicle body state determination unit 53 determines that the vehicle speed V is equal to or less than a predetermined threshold value Vth (V≦Vth), i.e., the vehicle body is stopped, the validity/invalidity determination unit 54 invalidates the second operation signal from the forward/reverse operation switch 34B acquired by the data acquisition unit 51 (disables the forward/reverse operation switch 34B).

When the validity/invalidity determination unit 54 determines to validate the second operation signal from the forward/reverse operation switch 34B, the traveling direction determination unit 55 determines whether the vehicle will move forward or backward based on the most recent operation signal (first operation signal and second operation signal) acquired by the data acquisition unit 51. In other words, when the forward/reverse operation switch 34B is in an enabled state, the controller 5 controls the forward/reverse movement of the vehicle based on the operation signal of the forward/reverse operation lever 34A or the forward/reverse operation switch 34B, whichever was most recently operated.

Specifically, if the data acquisition unit 51 acquires the second operation signal after the first operation signal, the traveling direction determination unit 55 determines whether the vehicle will move forward or backward based on the second operation signal, i.e., in response to the operation of the forward/reverse operation switch 34B. On the other hand, if the data acquisition unit 51 acquires the first operation signal after the second operation signal, the traveling direction determination unit 55 determines whether the vehicle will move forward or backward (forward, reverse, or stopped) based on the first operation signal, i.e., in response to the operation of the forward/reverse operation lever 34A.

Furthermore, if the validity/invalidity determination unit 54 determines to invalidate the second operation signal from the forward/reverse operation switch 34B, the traveling direction determination unit 55 determines whether the vehicle will move forward or backward (forward, backward, or stopped) based on the first operation signal from the forward/reverse operation lever 34A acquired by the data acquisition unit 51.

The signal output unit 56 outputs control signals to the forward solenoid valve 41 and the reverse solenoid valve 42, respectively, according to the vehicle's travel direction (forward, reverse, or stopped) determined by the travel direction determination unit 55.

Furthermore, when the switching determination unit 52 determines that the switching signal output from the changeover switch 39 is a valid command and the validity/invalidation determination unit 54 determines that the second operation signal from the forward/reverse operation switch 34B is valid, the signal output unit 56 outputs a first valid display signal to the monitor 35.

This "first valid indication signal" is an effective indication signal that indicates that both the forward/reverse operation lever 34A and the forward/reverse operation switch 34B are effective because the switching signal output from the changeover switch 39 is an effective command.

On the other hand, if the switching determination unit 52 determines that the switching signal output from the changeover switch 39 is an invalid command, but the vehicle body state determination unit 53 determines that the vehicle body is moving, and the validity/invalidity determination unit 54 determines that the second operation signal from the forward/reverse operation switch 34B is valid, the signal output unit 56 outputs a second validity indication signal, which is different from the first validity indication signal, to the monitor 35.

This "second valid indication signal" is an valid indication signal that indicates that the switching signal output from the changeover switch 39 has switched from an enable command to an disable command, but that both the forward/reverse operation lever 34A and the forward/reverse operation switch 34B are enabled because the vehicle is moving. Therefore, the first valid indication signal and the second valid indication signal have in common the fact that they indicate that both the forward/reverse operation lever 34A and the forward/reverse operation switch 34B are enabled, but the conditions under which this indication is displayed are different.

Then, when the switching determination unit 52 determines that the switching signal output from the changeover switch 39 is an invalid command, the vehicle body state determination unit 53 determines that the vehicle body is stopped, and the validity/invalidity determination unit 54 determines that the second operation signal from the forward/reverse operation switch 34B should be invalidated, the signal output unit 56 outputs an invalid display signal to the monitor 35.

This "invalid display signal" is an indication that the forward/reverse operation switch 34B is invalid (only the forward/reverse operation lever 34A is valid) because the switching signal output from the changeover switch 39 while the vehicle is stopped is an invalid command.

Here, Figure 4 shows an example of the display on monitor 35.

The first display D01 shown on the left side of Figure 4 is the display content of the monitor 35 when the signal output unit 56 outputs a first valid display signal to the monitor 35. The first display D01 is composed of a forward mark 351, which is a white upward arrow with the letter "F" inside; a reverse mark 352, which is a white downward arrow with the letter "R" inside; a lever valid mark 353, which is the valid mark for the forward/reverse operation lever 34A and is indicated by a leftward arrow located between the forward mark 351 and the reverse mark 352; and a switch valid mark 354, which is the valid mark for the forward/reverse operation switch 34B and is indicated by a triangle on the opposite side of the lever valid mark 353.

The second display D02 shown in the center of Figure 4 is the display content of the monitor 35 when a second valid display signal is output from the signal output unit 56 to the monitor 35. Like the first display D01, the second display D02 is composed of a forward mark 351, a backward mark 352, a lever valid mark 353, and a switch valid mark 354. However, unlike the first display D01, the second display D02 has, for example, a yellow background that lights up or flashes. Note that in Figure 4, the differences between the second display D02 and the first display D01 are indicated by the sandy area.

The third display D03 shown on the right side of Figure 4 is the display content of the monitor 35 when an invalid display signal is output from the signal output unit 56 to the monitor 35. The third display D03 is composed of a forward mark 351, a reverse mark 352, and a lever valid mark 353. In the third display D03, the forward/reverse operation switch 34B is invalid, so the switch valid mark 354 is not displayed.

In this way, the monitor 35 displays the first display D01 based on the first valid display signal, the second valid display signal based on the second valid display signal, and the third display D03 based on the invalid display signal. Therefore, by looking at the display on the monitor 35, the operator can instantly confirm the state of the forward/reverse operation lever 34A and the state of the forward/reverse operation switch 34B.

(Processing within the controller 5)
Next, a specific flow of processing executed by the controller 5 will be described with reference to FIG.

Figure 5 is a flowchart showing the flow of processing executed by the controller 5 according to the first embodiment.

In the controller 5, the data acquisition unit 51 first acquires the first operation signal output from the forward/reverse operation lever 34A, the second operation signal output from the forward/reverse operation switch 34B, and the switching signal output from the selector switch 39 (step S501).

Next, the switching determination unit 52 determines whether the switching signal acquired in step S501 is a valid command or an invalid command (step S502).

If it is determined in step S502 that the switching signal output from the selector switch 39 is a valid command (step S502/valid command), the validity/invalidation determination unit 54 validates the second operation signal from the forward/reverse operation switch 34B obtained in step S501 (step S503). Subsequently, the signal output unit 56 outputs a first valid display signal for the first display D01 to the monitor 35 (step S504).

Next, the traveling direction determination unit 55 determines whether the vehicle body will travel forward or backward based on the most recent of the first and second operation signals acquired in step S501 (step S505). The signal output unit 56 then outputs control signals to the forward solenoid valve 41 and the reverse solenoid valve 42, respectively, according to the traveling state of the vehicle body (forward, reverse, or stopped) determined in step S505 (step S506). The controller 5 then returns to step S501 and repeats each process.

Furthermore, if it is determined in step S502 that the switching signal output from the changeover switch 39 is an invalid command (step S502/invalid command), the data acquisition unit 51 acquires the vehicle speed V detected by the vehicle speed sensor 40 (step S507).

Next, the vehicle body state determination unit 53 determines whether the vehicle speed V acquired in step S507 is equal to or less than a predetermined threshold value Vth, i.e., whether the vehicle body is stopped (step S508).

If it is determined in step S508 that the vehicle speed V is greater than the predetermined threshold value Vth (V > Vth), i.e., that the vehicle body is moving (step S508/NO), and the current second operation signal is valid (step S500/valid), the validity/invalidation determination unit 54 keeps the second operation signal from the forward/reverse operation switch 34B valid (maintains the valid state of the forward/reverse operation switch 34B) (step S509).

Next, the signal output unit 56 outputs a second valid display signal for the second display D02 to the monitor 35 (step S510), and proceeds to processing in step S505.

On the other hand, if it is determined in step S508 that the vehicle speed V is equal to or less than the predetermined threshold value Vth (V≦Vth), i.e., that the vehicle body is stopped (step S508/YES), the validity/invalidation determination unit 54 invalidates the second operation signal from the forward/reverse operation switch 34B acquired in step S501 (step S511).

Note that even if it is determined in step S508 that the vehicle is moving and the current second operation signal is invalid in step S500 (step S500/Invalid), the process proceeds to step S511.

Next, the signal output unit 56 outputs an invalid display signal related to the third display D03 to the monitor 35 (step S512).

Next, the traveling direction determination unit 55 determines whether the vehicle body is to travel forward or backward based on the first operation signal from the forward/reverse operation lever 34A acquired in step S501 (step S513). Then, the signal output unit 56 outputs control signals to the forward solenoid valve 41 and the reverse solenoid valve 42, respectively, according to the traveling state of the vehicle body (forward, reverse, or stopped) determined in step S513 (step S506).

In this way, even if the switching signal output from the changeover switch 39 is switched from an enabled command to an disabled command due to, for example, an erroneous operation while the vehicle is moving, the controller 5 maintains the enabled state of the forward/reverse operation switch 34B until the vehicle comes to a stop. On the other hand, if the switching signal output from the changeover switch 39 is switched from an enabled command to an disabled command while the vehicle is stopped, the controller 5 maintains the disabled state of the forward/reverse operation switch 34B even if the vehicle starts to move thereafter.

Furthermore, when the switching signal output from the changeover switch 39 is switched from an inactive command to an active command, the forward/reverse operation switch 34B is set to the active state regardless of whether the vehicle is moving or stopped.

In the flowchart shown in Figure 5, the signal output unit 56 outputs each display signal to the monitor 35 (steps S504, S510, S512), and then the traveling direction determination unit 55 determines whether the vehicle body will move forward or backward (steps S505, S513). However, the processes do not necessarily have to be performed in this order; these processes may be performed in the reverse order of that shown in Figure 5, or may be performed in parallel.

Here, the specific state of each device when processing is executed within the controller 5 will be explained with reference to Figure 6.

Figure 6 is a table showing the state of the vehicle body and the changes in the display on the monitor 35 when the selector switch 39, forward/reverse operation lever 34A, and forward/reverse operation switch 34B are operated.

As shown by Nos. 1 to 3 in the table in Figure 6, when the state (position) of the selector switch 39 is enabled (enabled position), both the first operation signal from the forward/reverse operation lever 34A and the second operation signal from the forward/reverse operation switch 34B are enabled, regardless of whether the vehicle is moving (e.g., V = 5 km/h) or stopped (e.g., V = 0 km/h). As a result, the state of the vehicle (progress) is determined based on the most recent operation signal input to the controller 5, and the first display D01 is displayed on the monitor 35.

In No. 2 and No. 3 in the table in Figure 6, the forward/reverse operation lever 34A is operated to the neutral position N, while the forward/reverse operation switch 34B is operated to the forward position F. In this case, when the second operation signal from the forward/reverse operation switch 34B is input to the controller 5 after the first operation signal from the forward/reverse operation lever 34A, the vehicle body moves forward (F) in accordance with the second operation signal from the forward/reverse operation switch 34B.

Next, as shown in No. 4 and No. 5 in the table of FIG. 6, when the state (position) of the selector switch 39 is disabled (disabled position) and the vehicle is moving (for example, V = 5 km/h), as in No. 1 to 3, both the first operation signal from the forward/reverse operation lever 34A and the second operation signal from the forward/reverse operation switch 34B are valid, and the state (progress) of the vehicle is determined based on the most recent operation signal input to the controller 5. However, the second display D02 is displayed on the monitor 35.

In No. 4 in the table of Figure 6, like No. 2 and No. 3, the forward/reverse operation lever 34A is operated to the neutral position N, while the forward/reverse operation switch 34B is operated to the forward position F. In this case, when the second operation signal from the forward/reverse operation switch 34B is input to the controller 5 after the first operation signal from the forward/reverse operation lever 34A, the vehicle body moves forward (F) in accordance with the second operation signal from the forward/reverse operation switch 34B.

As shown by Nos. 6 to 8 in the table in Figure 6, when the selector switch 39 is disabled and the vehicle is stopped (for example, V = 0 km/h), the second operation signal from the forward/reverse operation switch 34B is disabled, so the vehicle's state (travel status) is determined based on the first operation signal from the forward/reverse operation lever 34A, and the third display D03 is displayed on the monitor 35.

In No. 7 in the table of FIG. 6, the forward/reverse operation lever 34A is operated to the neutral position N, while the forward/reverse operation switch 34B is operated to the forward position F. In this case, the vehicle body stops (N) in accordance with the first operation signal from the forward/reverse operation lever 34A. Also, in No. 8 in the table of FIG. 6, the forward/reverse operation lever 34A is operated to the reverse position R, while the forward/reverse operation switch 34B is operated to the forward position F. In this case, the vehicle body moves backward (R) in accordance with the first operation signal from the forward/reverse operation lever 34A.

In this way, even if the changeover switch 39 is set to the disabled state, the second operation signal output from the forward/reverse operation switch 34B is valid while the vehicle is moving. Therefore, when the operator needs to quickly switch between forward and reverse or stop the vehicle, the operator can use the forward/reverse operation switch 34B located close to them to control the direction of travel of the vehicle.

On the other hand, when the changeover switch 39 is disabled and the vehicle is stopped, it is unlikely that the operator will suddenly want to switch between forward and reverse. In this case, by disabling the second operation signal output from the forward/reverse operation switch 34B, it is possible to prevent the operator from accidentally operating the forward/reverse operation switch 34B and causing the vehicle to travel unintentionally.

Furthermore, in this embodiment, when both the first operation signal from the forward/reverse operation lever 34A and the second operation signal from the forward/reverse operation switch 34B are valid, the forward/reverse movement of the vehicle body is determined based on the most recent operation signal input to the controller 5, making it possible to control the forward/reverse movement of the vehicle body more in line with the operator's intentions.

As described above, with this wheel loader 1, even if the selector switch 39 is erroneously operated while the vehicle body is traveling, it is possible to switch between forward and reverse travel and continue traveling as intended by the operator.

Second Embodiment
Next, a controller 5A according to a second embodiment of the present invention will be described with reference to Figures 7 and 8. In Figures 7 and 8, components that are common to those described for the controller 5 according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted.

Figure 7 is a functional block diagram showing the functions of the controller 5A according to the second embodiment. Figure 8 is a flowchart showing the flow of processing executed by the controller 5A according to the second embodiment.

The controller 5A according to this embodiment includes a data acquisition unit 51A, a switching determination unit 52, an operation determination unit 57, a valid/invalid determination unit 54A, a traveling direction determination unit 55, and a signal output unit 56. The functional configurations of the switching determination unit 52, traveling direction determination unit 55, and signal output unit 56 in the controller 5A are the same as those in the controller 5 according to the first embodiment, and therefore will not be described below.

The data acquisition unit 51A acquires the first operation signal output from the forward/reverse operation lever 34A, the second operation signal output from the forward/reverse operation switch 34B, and the switching signal output from the selector switch 39.

When the switching determination unit 52 determines that the switching signal output from the selector switch 39 is an invalid command (step S502/invalid command), the operation determination unit 57 determines whether the forward/reverse operation lever 34A has been operated, i.e., whether the data acquisition unit 51A has acquired the first operation signal from the forward/reverse operation lever 34A (steps S514 and S514A).

If the switching determination unit 52 determines that the switching signal output from the switch 39 is a valid command (step S502/valid command), the valid/invalid determination unit 54A validates the second operation signal from the forward/reverse operation switch 34B acquired by the data acquisition unit 51 (step S503), similar to the processing performed by the valid/invalid determination unit 54 of the controller 5 in the first embodiment.

Furthermore, if the switching determination unit 52 determines that the switching signal output from the switch 39 is an invalid command (step S502/invalid command) and the operation determination unit 57 determines that the forward/reverse operation lever 34A is not being operated (step S514A/NO), the valid/invalid determination unit 54A validates the second operation signal from the forward/reverse operation switch 34B (maintaining the valid state of the forward/reverse operation switch 34B) if the current second operation signal is valid (step S500/valid).

On the other hand, even if the switching determination unit 52 determines that the switching signal output from the switch 39 is an invalid command (step S502/invalid command) and the operation determination unit 57 determines that the forward/reverse operation lever 34A has not been operated (step S514A/NO), if the current second operation signal is invalid (step S500/invalid), the valid/invalid determination unit 54A proceeds to step S511 and invalidates the second operation signal from the forward/reverse operation switch 34B.

Furthermore, if the operation determination unit 57 determines that the forward/reverse operation lever 34A has been operated (step S514A/YES), the validity/invalidation determination unit 54A invalidates the second operation signal from the forward/reverse operation switch 34B (step S511).

In other words, in this embodiment, the controller 5A determines whether the second operation signal from the forward/reverse operation switch 34B is valid or invalid based on whether the forward/reverse operation lever 34A is operated. If the switching signal output from the changeover switch 39 is switched from an enable command to an disable command and the forward/reverse operation lever 34A is operated, this indicates the operator's intention not to operate the forward/reverse operation switch 34B, and therefore there is no problem in invalidating the second operation signal from the forward/reverse operation switch 34B, regardless of whether the vehicle is moving or not.

On the other hand, even if the switching signal output from the changeover switch 39 is switched from an enabled command to an disabled command, if the forward/reverse operation lever 34A is not being operated, there is a possibility that the operator will suddenly operate the forward/reverse operation switch 34B. In this case, it is necessary to keep the second operation signal from the forward/reverse operation switch 34B enabled.

In this way, instead of determining the state of the vehicle body (moving or stopped), the controller 5A may determine whether the forward/reverse operation lever 34A is being operated, and based on the result of this determination, determine whether the second operation signal from the forward/reverse operation switch 34B is valid or invalid. In this case, the same effects and advantages as those in the first embodiment can be achieved.

Third Embodiment
Next, a wheel loader 1 according to a third embodiment of the present invention will be described with reference to Figures 9 to 11. In Figures 9 to 11, components that are common to those described for the wheel loader 1 according to the first embodiment are given the same reference numerals, and descriptions thereof will be omitted.

Figure 9 shows an example of the interior configuration of the driver's cab 12 according to the third embodiment, as viewed from the ceiling side. Figure 10 is an enlarged view of the joystick lever 6 in Figure 9.

In this embodiment, as shown in Figure 9, the driver's cab 12 is provided with a joystick lever 6 for switching the vehicle's direction of travel. As shown in Figure 10, the joystick lever 6 is provided with a steering operation unit 61 for switching the vehicle's direction of travel between left and right, and a switch-type forward/reverse operation unit 62 for switching the vehicle's direction of travel between forward and backward.

In other words, in this embodiment, a steering operation unit 61 is provided on the joystick lever 6 in place of the handle 32 in the first and second embodiments, and a forward/reverse operation unit 62 is provided on the joystick lever 6 in place of the forward/reverse operation lever 34A and forward/reverse operation switch 34B in the first and second embodiments.

In the first and second embodiments, the wheel loader 1 was equipped with two forward/reverse operation devices (forward/reverse operation lever 34A and forward/reverse operation switch 34B), but in this embodiment, it is equipped with only one forward/reverse operation device (forward/reverse operation unit 62).

As shown in Figure 9, the joystick lever 6 is attached to the tip (front end) of the left armrest 31L of the driver's seat 31, allowing the operator to operate the steering operation unit 61 and forward/reverse operation unit 62 while resting their left arm on the left armrest 31L.

The vehicle turns left when the operator tilts the steering control unit 61 to the left, and turns right when the operator tilts the steering control unit 61 to the right. In Figure 10, the direction in which the steering control unit 61 is tilted is indicated by an arrow.

The forward/reverse operation unit 62 has three positions: forward position F, reverse position R, and neutral position N, similar to the forward/reverse operation lever 34A and forward/reverse operation switch 34B in the first embodiment.

Furthermore, like the forward/reverse operation switch 34B in the first embodiment, the forward/reverse operation unit 62 is a switch type located very close to the operator, making it easy to operate, but prone to operating errors. Therefore, in this embodiment as well, a selector switch 39 is provided on the side console 38 as a switching device for switching the forward/reverse operation unit 62 between an enabled and disabled state.

Next, the processing within the controller 5 according to this embodiment will be described with reference to FIG. 11. Note that the functional components of the controller 5 according to this embodiment are the same as those of the controller 5 according to the first embodiment (see FIG. 3), and therefore will be denoted by the same reference numerals in the following description.

Figure 11 is a flowchart showing the flow of processing executed by the controller 5 according to the third embodiment.

In the controller 5 according to this embodiment, the data acquisition unit 51 first acquires the operation signal output from the forward/reverse operation unit 62 and the switching signal output from the selector switch 39 (step S501B).

Next, the switching determination unit 52 determines whether the switching signal output from the changeover switch 39 is a valid command or an invalid command based on the switching signal from the changeover switch 39 acquired in step S501B (step S502).

If it is determined in step S502 that the switching signal output from the selector switch 39 is a valid command (step S502/valid command), the validity/invalidation determination unit 54 validates the operation signal from the forward/reverse operation unit 62 acquired in step S501B (step S503), and the signal output unit 56 outputs a first valid display signal to the monitor 35 (step S504).

Next, the traveling direction determination unit 55 determines whether the vehicle body will travel forward or backward based on the operation signal from the forward/reverse operation unit 62 acquired in step S501B (step S515). Then, the signal output unit 56 outputs control signals to the forward solenoid valve 41 and the reverse solenoid valve 42, respectively, according to the traveling direction of the vehicle body (forward, reverse, or stopped) determined in step S515 (step S506).

Furthermore, if it is determined in step S502 that the switching signal output from the changeover switch 39 is an invalid command (step S502/invalid command), the vehicle body state determination unit 53 determines the vehicle body's running state (stopped state) based on the vehicle speed V acquired in step S507 (step S508).

If it is determined in step S508 that the vehicle body is stopped (V≦Vth) (step S508/YES), the validity/invalidation determination unit 54 invalidates the operation signal from the forward/reverse operation unit 62 acquired in step S501B (step S511).

Next, the signal output unit 56 outputs an invalid display signal to the monitor 35 (step S512). The controller 5 then maintains the current forward/reverse movement of the vehicle body (step S516) and proceeds to step S506.

In this embodiment, the only forward/reverse operation device for operating the vehicle body forward or backward is the forward/reverse operation unit 62, so the vehicle body cannot switch between forward and reverse unless the switching signal output from the changeover switch 39 switches from an invalid command to an valid command (step S502/valid command).

On the other hand, if it is determined in step S508 that the vehicle is moving (V > Vth) (step S508/NO) and the current operation signal from the forward/reverse operation unit 62 is valid (step S500/valid), the validity/invalidation determination unit 54 maintains the valid state of the forward/reverse operation unit 62 (step S509), the signal output unit 56 outputs a second valid display signal to the monitor 35 (step S510), and then the process proceeds to step S515.

If it is determined in step S508 that the vehicle is moving (V>Vth) (step S508/NO) and the current operation signal from the forward/reverse operation unit 62 is invalid (step S500/Invalid), the process proceeds to step S511.

In this way, even if multiple forward/reverse operation devices are not provided within the cab 12, the present invention can be applied and provides the same functions and effects as those of the first embodiment.

Fourth Embodiment
Next, a wheel loader 1 according to a fourth embodiment of the present invention will be described with reference to Figures 12 and 13. In Figures 12 and 13, components that are common to those described for the wheel loader 1 according to the first and third embodiments are given the same reference numerals, and description thereof will be omitted.

Figure 12 shows an example of the interior configuration of the driver's cab 12 according to the fourth embodiment, showing the interior of the driver's cab 12 as seen from the ceiling side.

In this embodiment, as in the third embodiment, a joystick lever 6 provided with a steering operation unit 61 and a forward/reverse operation unit 62 is attached to the tip (front end) of the left armrest 31L of the driver's seat 31.

Also, as in the first embodiment, a forward/reverse operation switch 34B is provided on the side console 38 to the right of the first work operation lever 36A and the second work operation lever 36B. The switch unit 390 of the side console 38 includes a first selector switch 39A that switches the forward/reverse operation unit 62 between an enabled and disabled state, and a second selector switch 39B that switches the forward/reverse operation switch 34B between an enabled and disabled state.

In other words, in this embodiment, the wheel loader 1 is equipped with two forward/reverse operation devices (the forward/reverse operation unit 62 and the forward/reverse operation switch 34B) and two switching devices (the first switch 39A and the second switch 39B).

Because both the forward/reverse operation unit 62 and the forward/reverse operation switch 34B are switch-type devices located very close to the operator, making them prone to erroneous operation, a first selector switch 39A is provided in the driver's cab 12 as a switching device corresponding to the forward/reverse operation unit 62, and a second selector switch 39B is provided in the driver's cab 12 as a switching device corresponding to the forward/reverse operation switch 34B.

Next, the processing within the controller 5 according to this embodiment will be described with reference to Figure 13. Note that the functional components of the controller 5 according to this embodiment are the same as those of the controller 5 according to the first embodiment (see Figure 3), and therefore will be denoted by the same reference numerals in the following description.

Figure 13 is a flowchart showing the flow of processing executed by the controller 5 according to the fourth embodiment.

In the controller 5 according to this embodiment, the data acquisition unit 51 first acquires the second operation signal output from the forward/reverse operation switch 34B, the third operation signal output from the forward/reverse operation unit 62 (corresponding to the "operation signal output from the forward/reverse operation unit 62" in the third embodiment), the first switching signal output from the first changeover switch 39A, and the second switching signal output from the second changeover switch 39B (step S521).

Next, the switching determination unit 52 determines whether the switching signal output from the first switching switch 39A is a valid command or an invalid command based on the first switching signal from the first switching switch 39A acquired in step S521 (step S522).

If it is determined in step S522 that the switching signal output from the first changeover switch 39A is a valid command (step S522/valid command), the switching determination unit 52 then determines whether the switching signal output from the second changeover switch 39B is a valid command or an invalid command based on the second switching signal from the second changeover switch 39B acquired in step S521 (step S523).

If it is determined in step S523 that the switching signal output from the second selector switch 39B is a valid command (step S523/valid command), the validity/invalidation determination unit 54 validates the second operation signal from the forward/reverse operation switch 34B and the third operation signal from the forward/reverse operation unit 62 obtained in step S521 (step S524). Subsequently, the signal output unit 56 outputs a first valid display signal to the monitor 35 (step S525).

Next, the traveling direction determination unit 55 determines whether the vehicle body will travel forward or backward based on the most recent of the second and third operation signals acquired in step S521 (step S526). The signal output unit 56 then outputs control signals to the forward solenoid valve 41 and the reverse solenoid valve 42, respectively, according to the traveling direction of the vehicle body (forward, reverse, or stopped) determined in step S526 (step S527).

Also, if it is determined in step S523 that the switching signal output from the second changeover switch 39B is an invalid command (step S523/invalid command), the data acquisition unit 51 acquires the vehicle speed V detected by the vehicle speed sensor 40 (step S531). Next, the vehicle body state determination unit 53 determines whether the vehicle body is stopped based on the vehicle speed V acquired in step S531 (step S532).

If it is determined in step S532 that the vehicle body is stopped (step S532/YES), the validity/invalidation determination unit 54 invalidates the second operation signal from the forward/reverse operation switch 34B acquired in step S521 (step S533).

Next, the signal output unit 56 outputs a first invalid display signal to the monitor 35 (step S534). This "first invalid display signal" is an invalid display signal that indicates that, of the second operation signal from the forward/reverse operation switch 34B and the third operation signal from the forward/reverse operation unit 62, the second operation signal from the forward/reverse operation switch 34B is invalid (while the third operation signal from the forward/reverse operation unit 62 is valid).

Next, the traveling direction determination unit 55 determines whether the vehicle body should move forward or backward based on the third operation signal from the forward/reverse operation unit 62 acquired in step S521 (step S535), and processing in the controller 5 proceeds to step S527.

On the other hand, if it is determined in step S532 that the vehicle is moving (step S532/NO), the validity/invalidation determination unit 54 validates both the second operation signal from the forward/reverse operation switch 34B acquired in step S521 and the third operation signal from the forward/reverse operation unit 62 (step S536). Next, the signal output unit 56 outputs a second valid display signal to the monitor 35 (step S537), and processing in the controller 5 proceeds to step S526.

Also, if it is determined in step S522 that the switching signal output from the first changeover switch 39A is an invalid command (step S522/invalid command), the data acquisition unit 51 acquires the vehicle speed V detected by the vehicle speed sensor 40 (step S541). Next, the vehicle body state determination unit 53 determines whether the vehicle body is stopped based on the vehicle speed V acquired in step S541 (step S542).

If it is determined in step S542 that the vehicle body is stopped (step S542/YES), the validity/invalidation determination unit 54 invalidates the third operation signal from the forward/reverse operation unit 62 acquired in step S521 (step S543).

Next, the signal output unit 56 outputs a second invalid display signal to the monitor 35 (step S544). This "second invalid display signal" is an invalid display signal that indicates that, of the second operation signal from the forward/reverse operation switch 34B and the third operation signal from the forward/reverse operation unit 62, the third operation signal from the forward/reverse operation unit 62 is invalid (the second operation signal from the forward/reverse operation switch 34B is valid).

Next, the traveling direction determination unit 55 determines whether the vehicle body should move forward or backward based on the second operation signal from the forward/reverse operation switch 34B acquired in step S521 (step S545), and processing in the controller 5 proceeds to step S527.

On the other hand, if it is determined in step S542 that the vehicle is moving (step S542/NO), processing in the controller 5 proceeds to steps S536 and S537.

In this way, even when multiple forward/reverse operation devices (forward/reverse operation switch 34B and forward/reverse operation unit 62) are provided within the cab 12 and a selector switch (first selector switch 39A and second selector switch 39B) is provided corresponding to each forward/reverse operation device, the present invention can be applied and provides the same functions and effects as those of the first embodiment.

In FIG. 13, when the switching signal output from the first selector switch 39A is an invalid command (step S522/invalid command), the validity/invalidation determination unit 54 determines whether the third operation signal from the forward/reverse operation unit 62 is valid or invalid based on the state of the vehicle body (steps S542, S543, S536). However, this is not limited to this, and as in the second embodiment, the validity/invalidation of the third operation signal from the forward/reverse operation unit 62 may be determined based on whether the other forward/reverse operation device, the forward/reverse operation switch 34B, has been operated. The same applies when the switching signal output from the second selector switch 39B is an invalid command (step S523/invalid command).

The above describes an embodiment of the present invention. However, the present invention is not limited to the above embodiment and includes various modifications. For example, the above embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to having all of the described configurations. Furthermore, it is possible to replace part of the configuration of this embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of this embodiment. Furthermore, it is possible to add, delete, or replace part of the configuration of this embodiment with other configurations.

For example, in the above embodiments, the changeover switches 39, 39A, and 39B are provided to correspond to switch-type forward/reverse operation devices, but this is not limited thereto and they may also be provided to correspond to lever-type forward/reverse operation devices.

Furthermore, in the above embodiments, a switch-type or lever-type forward/reverse operation device has been described as one form of forward/reverse operation device, but there are no particular limitations on the operation type of the forward/reverse operation device.

Furthermore, in each of the above embodiments, a switch type has been described as one form of switching device, but there are no particular limitations on the switching means of the switching device.

Furthermore, in each of the above embodiments, a wheel loader 1 has been used as an example of one type of work vehicle, but this is not limiting and other work vehicles capable of moving forward and backward may also be used.

1: Wheel loader (work vehicle)
5, 5A: Controller 12: Driver's cab 34A: Forward/reverse operation lever (first forward/reverse operation device)
34B: forward/reverse operation switch (second forward/reverse operation device)
39: Changeover switch (changeover device)
39A: First changeover switch (changeover device)
39B: Second changeover switch (changeover device)
40: Vehicle speed sensor (driving state detection device)
62: Forward/forward operation unit (forward/forward operation device)

Claims (7)

a first forward/reverse operation device and a second forward/reverse operation device provided in the driver's cab for operating the forward and reverse movement of the vehicle body;
a switching device provided in the driver's cab and configured to output, as a switching signal, an enable command for enabling the second forward/reverse operation device and an disable command for disabling the second forward/reverse operation device;
a controller that controls forward and backward movement of the vehicle body based on the switching signal output from the switching device, a first operation signal output from the first forward/reverse operation device, and a second operation signal output from the second forward/reverse operation device;
In a work vehicle equipped with
a running state detection device for detecting the running state of the vehicle body;
The controller
determining whether the vehicle body is moving or stopped based on the running state detected by the running state detection device;
a second forward/reverse operation device that is maintained in the enabled state when the switching signal output from the switching device is switched from the enabled command to the disabled command while the vehicle body is traveling, and that controls the forward/reverse movement of the vehicle body based on the first operation signal output from the first forward/reverse operation device and the second operation signal output from the second forward/reverse operation device. The work vehicle according to claim 1,
The controller
a first operation signal output from the first forward/reverse operation device, the second forward/reverse operation device being set to the disabled state, and the forward/reverse movement of the vehicle body being controlled based on the first operation signal output from the first forward/reverse operation device, when it is determined that the vehicle body is stopped after the switching signal output from the switching device is switched from the enabled command to the disabled command while the vehicle body is traveling. The work vehicle according to claim 1,
The controller
When the second forward/reverse operation device is in the enabled state, the forward/reverse movement of the vehicle body is controlled based on an operation signal of the forward/reverse operation device that was operated last out of the first forward/reverse operation device and the second forward/reverse operation device. The work vehicle according to claim 1,
a display device that displays a control state of the first forward/reverse operation device and the second forward/reverse operation device by the controller,
The controller
When the switching signal output from the switching device is the valid command, a first valid indication signal is output to the display device to indicate that both the first forward/reverse operation device and the second forward/reverse operation device are valid,
When the switching signal output from the switching device is switched from the valid command to the invalid command while the vehicle body is traveling, a second valid indication signal indicating that both the first forward/reverse operation device and the second forward/reverse operation device are valid is output to the display device, the second valid indication signal being different from the first valid indication signal;
A work vehicle characterized in that, when the switching signal output from the switching device while the vehicle body is stopped is the disable command, an invalid display signal indicating that the second forward/reverse operation device is disabled is output to the display device. a first forward/reverse operation device and a second forward/reverse operation device provided in the driver's cab for operating the forward and reverse movement of the vehicle body;
a switching device provided in the driver's cab and configured to output, as a switching signal, an enable command for enabling the second forward/reverse operation device and an disable command for disabling the second forward/reverse operation device;
a controller that controls forward and backward movement of the vehicle body based on the switching signal output from the switching device, a first operation signal output from the first forward/reverse operation device, and a second operation signal output from the second forward/reverse operation device;
In a work vehicle equipped with
The controller
when the switching signal output from the switching device is switched from the valid command to the invalid command, the second forward/reverse operation device is maintained in the valid state until the first forward/reverse operation device is operated, and forward/reverse movement of the vehicle body is controlled based on the first operation signal output from the first forward/reverse operation device and the second operation signal output from the second forward/reverse operation device;
a switching signal output from the switching device being the disable command, and when the first forward/reverse operation device is operated, the second forward/reverse operation device is set to the disabled state, and the forward/reverse movement of the vehicle body is controlled based on the first operation signal output from the first forward/reverse operation device. a forward/reverse operation device provided in the driver's cab for operating the forward/reverse movement of the vehicle body;
a switching device provided in the driver's cab for outputting, as a switching signal, an enable command for putting the forward/reverse operation device into an enable state and an disable command for putting the forward/reverse operation device into an disable state;
a controller that controls forward and backward movement of the vehicle body based on the switching signal output from the switching device and the operation signal output from the forward and backward movement operation device;
In a work vehicle equipped with
a running state detection device for detecting the running state of the vehicle body;
The controller
determining whether the vehicle body is moving or stopped based on the running state of the vehicle body detected by the running state detection device;
A work vehicle characterized in that, when the switching signal output from the switching device is switched from the enable command to the disable command while the vehicle body is traveling, the forward/reverse operation device is maintained in the enable state. The work vehicle according to claim 6,
The controller
a forward/reverse operation device that is set to the disabled state when it is determined that the vehicle body is stopped after the switching signal output from the switching device is switched from the enabled command to the disabled command while the vehicle body is traveling.