JPH02220934A - Travel speed controlling device of cargo handling vehicle - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a traveling speed control device applied to a cargo handling vehicle such as a forklift.

[Prior Art] Conventionally, many cargo handling vehicles such as forklifts use a single engine as both a drive source for traveling and a drive source for cargo handling. That is, based on that one engine, the drive wheels are driven via a clutch and a transmission, and the cargo handling hydraulic pump is driven to drive a lift cylinder and a lift cylinder via a hydraulic circuit.
It is designed to operate each cargo handling cylinder such as a tilt cylinder.

Therefore, in order to obtain the desired engine output accompanying the cargo handling operation, the engine speed is controlled based on the amount of operation of the operating means such as the cargo handling lever, and the fluctuation in traveling speed based on the control of the engine speed is accelerated. A speed control device for cargo handling operations has been proposed that is configured to control by clutch transmission torque or brake force in order to adjust the travel speed to the amount of pedal depression (Japanese Patent Laid-Open No. 61-238).
535 Publication).

According to this speed control device, the traveling speed during cargo handling operations can be arbitrarily controlled by operating the cargo handling lever etc. and the accelerator pedal. It was possible to eliminate the inching pedal used for cargo handling, and improve the operability of cargo handling operations.

[Problems to be Solved by the Invention] However, in the speed control device, there is room for improvement in terms of smoothness of traveling speed control.

In other words, when increasing the traveling speed to a desired speed, the clutch transmission torque is controlled by controlling the clutch drive means, etc., but in this case, it is said that smooth speed control becomes difficult due to clutch engagement shock. There was a risk.

This invention was made in view of the above-mentioned circumstances, and its purpose is to increase the engine speed based on the operation of an operating means such as a cargo handling lever for cargo handling operations, and to increase the engine rotation speed. An object of the present invention is to provide a traveling speed control device for a cargo handling vehicle that can smoothly asymptotize a fluctuation in traveling speed due to an increase in the number of vehicles to a traveling speed corresponding to an operation amount of an operating means such as an accelerator pedal.

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a means for adjusting the throttle opening of the engine, and a means for adjusting the connection state of the clutch that turns on and off the output from the engine to the transmission. A clutch drive means, a vehicle speed detection means for detecting the running speed of the vehicle, an accelerator operation amount detection means for detecting the operation amount of the accelerator operation means operated to indicate the running speed, and an accelerator operation amount detection means operated for performing cargo handling work. A cargo handling vehicle is equipped with a cargo handling operation amount detection means for detecting the operation amount of the cargo handling operation means, and a vehicle speed data storage means that stores in advance the vehicle speed corresponding to the operation amount of the accelerator operation means as vehicle speed data, and an accelerator operation amount. A vehicle speed deviation calculation means for determining a target vehicle speed for an operation amount detected by the detection means based on vehicle speed data, and calculating a vehicle speed deviation between the target vehicle speed and an actual vehicle speed detected by the vehicle speed detection means, and a size of the vehicle speed deviation. A connection amount data storage means that stores in advance the connection amount of the clutch per unit time for the vehicle speed deviation as connection amount data, and a periodic interval for slightly moving the clutch to engage Vt in response to the magnitude of the vehicle speed deviation is stored in advance as interval data. When it is determined that the cargo handling operation means has been operated based on the detection by the interval data storage means and the cargo handling operation amount detection means, the throttle opening adjustment means is driven and controlled to increase the throttle opening, and the clutch is disengaged. After the throttle/clutch control means controls the clutch drive means to temporarily return it to the side, and after the throttle/clutch control means performs control, the clutch is brought into a predetermined half-connected state in order to bring the actual vehicle speed asymptotically close to the target vehicle speed. a first clutch control means that determines the amount of engagement of the clutch per unit time with respect to the magnitude of the vehicle speed deviation based on the amount of engagement data, and controls the clutch driving means in accordance with the determined amount of engagement; After the first clutch control means has been controlled, a periodic interval at which the clutch is slightly engaged is determined based on the interval data in order to bring the actual vehicle speed closer to the target vehicle speed. , and second clutch control means for driving and controlling the clutch drive means according to the determined periodic interval.

[Function] Therefore, cargo handling operations should be carried out when the cargo handling vehicle is running at low speed. The controller determines that the throttle opening is increased and controls the throttle opening adjusting means to increase the throttle opening for cargo handling work, and also controls the clutch driving means to temporarily return the clutch to the disengaged side.As a result, the engine rotational speed increases. increases, making it possible to accelerate the cargo handling speed, and the clutch transmission torque is temporarily weakened.

Further, the vehicle speed deviation calculation means determines a target vehicle speed for the operation amount detected by the accelerator operation amount detection means based on the vehicle speed data stored in the vehicle speed data storage means, and calculates the target vehicle speed and the actual vehicle speed detected by the vehicle speed detection means. Calculate the vehicle speed deviation.

After the control by the throttle/clutch control means is performed, the first clutch control means controls the clutch according to the magnitude of the vehicle speed deviation in order to bring the clutch into a predetermined half-engaged state in order to bring the actual vehicle speed asymptotically close to the target vehicle speed. The amount of contact Vt per unit time is determined based on the connection amount data stored in the connection amount data storage means, and the clutch drive means is drive-controlled in accordance with the determined connection amount.

Further, after the first clutch control means is controlled, the second clutch control means is controlled.
The clutch control means determines, based on the interval data stored in the interval data storage means, a periodic interval at which the clutch is slightly engaged and moved in response to the magnitude of the vehicle speed deviation at that time in order to bring the actual vehicle speed closer to the target vehicle speed, The clutch drive means is drive-controlled according to the determined cycle interval.

As a result, even if the engine speed increases more than necessary, the clutch is gradually brought closer to a predetermined half-engaged state, and the actual vehicle speed is brought asymptotically to a traveling speed corresponding to the operation amount of the accelerator operation means.

[Embodiment] Hereinafter, an embodiment in which the present invention is embodied in a forklift will be described in detail with reference to FIGS. 1 to 11.

FIG. 1 shows the drive system mechanism and electrical configuration of a forklift, in which the output of an engine 1 is transmitted to a transmission 63 via a dry single-plate clutch (hereinafter simply referred to as "clutch") 2.
Further, the driving drive wheels 5 are driven forward and backward through the differential gear mechanism 4 at a predetermined gear ratio. In this embodiment, the engine 1 is also used as a drive source for a hydraulic pump 6 that supplies hydraulic oil to a lift cylinder for raising and lowering a cargo handling fork (not shown) and a tilt cylinder for tilting a mast. ing.

The throttle opening of the engine 1 is adjusted by the drive of a throttle actuator unit which is composed of a step motor as a throttle opening adjustment means, and the output shaft 1 of the engine 1 is
The rotational speed of a (engine rotational speed) is adjusted.

Further, the clutch 2 for turning on and off the output from the engine 1 to the transmission 3 is configured to move the clutch 2 relative to the stroke amount of the rod 8a, which extends > m based on the drive of the clutch drive actuator 8 as a clutch drive means. The connection state (connection position) of No. 2 is adjusted.

Further, the transmission 3 is switched between forward travel, neutral, and reverse travel based on the drive of its built-in forward/reverse switching actuator (as shown in the diagram), and is also switched between forward travel, neutral, and reverse travel based on the drive of the gear shift switching actuator (as shown in the diagram). Can be switched to 1st or 2nd speed. In this embodiment, forward/reverse switching and gear change of the transmission 3 are instructed by switching operations of a forward/reverse lever (not shown) provided at the driver's seat.

Next, an electrical configuration for driving and controlling each of the actuators 7, 8, etc. will be explained.

Engine rotation speed sensor 9 detects the rotation speed of output shaft 1 a of engine 1 and outputs the detection signal to input/output interface 10 .

The stroke detection sensor 11 is composed of a potentiometer, detects the stroke amount of the rod 8a of the clutch drive actuator 8, converts the detection signal into a digital signal by the A/D converter 12, and sends it to the human output interface IO.
Output to.

In addition, the input shaft rotation speed sensor 13 is connected to the input shaft 3a of the transmission 3.
The rotation speed (input shaft rotation speed) is detected and the detection signal is output to the input/output interface 10.

Further, a vehicle speed sensor 14 serving as vehicle speed detection means detects the rotational speed of the output shaft 3b of the transmission 3 relative to the vehicle speed, and outputs the detection signal to the input/output interface 10.

The accelerator sensor 15, which serves as an accelerator operation amount detection means, is composed of a potentiometer, and detects the operation amount (depression amount) of an accelerator pedal 16, which serves as an accelerator operation means provided in the driver's seat.
AC is detected, and the detection signal is converted into a digital signal by the A/D converter 17 and output to the input/output interface IO.

The lever sensor 18 as a cargo handling operation amount detection means detects the operation amount LC of a cargo handling lever (in this embodiment, a lift lever for driving a lift cylinder) 19 as a cargo handling operation means also provided in the driver's seat. The detection signal is A
The /D converter 20 converts the signal into a digital signal and outputs it to the input/output interface 10.

The microcomputer 21 includes a CPU (Central Processing Unit) 22 as vehicle speed deviation calculation means, throttle/clutch control means, first and second clutch control means, vehicle speed data storage means, connection amount data storage means, and interval data storage means. The program memory 23 consists of a read-only memory (ROM'), and the working memory 24 consists of a readable and rewritable memory (RAM) in which the results of arithmetic processing by the CPU 22 are temporarily stored. Then, the CPU 22 uses the program memory 2
It operates based on the control program stored in 3.

In the program memory 23, as shown in the map in FIG. 3, the engine rotation speed with respect to the operation amount LC of the cargo handling lever 19 is stored in advance as rotation speed data, and as shown in the map in FIG. Operation amount LC of bar 19
throttle for.

A throttle opening degree that corresponds to the rotational speed data is stored in advance as opening degree data. Further, the target vehicle speed corresponding to the depression amount AC of the accelerator pedal 16 is stored in advance in the program memory 23 as vehicle speed data, as shown in the map in FIG. Furthermore, as shown in the map in FIG. 7, the program memory 23 stores information on the clutch 2 per unit time (every control cycle) with respect to the vehicle speed deviation between the target vehicle speed determined based on the map of the vehicle speed data and the actual vehicle speed. The amount of connection is stored in advance as connection amount data, and the periodic interval at which the clutch 2 is slightly moved in connection in response to the vehicle speed deviation is stored in advance as interval data, as shown in the map in FIG.

The CPU 22 has each sensor 9, 11.13, 1415.18
The detection signal is input manually via the input/output interface 10.

Based on the detection signal from the engine rotation speed sensor 9, the CPU 22 determines the engine rotation speed relative to the engine output at the time. Further, the CPU 22 controls the transmission 3 via the clutch 2 based on the detection signal of the input shaft rotation speed sensor 13.
Furthermore, the CPU 22 determines the current vehicle speed based on the detection signal of the vehicle speed sensor 14.

Further, the CPU 22 inputs the detection signal of the lever sensor 18 corresponding to the operation amount LC of the cargo handling lever 19, determines the target opening degree for the operation amount LC based on the map shown in FIG. The target rotation speed relative to LC is determined based on the map shown in FIG. Then, the throttle actuator 7 is driven and controlled via the input/output interface 10 and the throttle/nottle actuator drive circuit 25 based on the determined target opening degree and target rotation speed.

Furthermore, the CPU 22 determines whether to start operating the accelerator pedal 16 based on the detection signal of the accelerator sensor 15. When it is determined that the pedal 16 is not operated, the clutch 2 is held in a completely disengaged state, and the pedal 16 is held in a completely disengaged state.
6 has been operated, the clutch drive actuator 8 is driven and controlled via the input/output interface 10 and the clutch actuator drive circuit 26 in order to connect the clutch 2.

Further, the CPU 22 inputs the detection signal of the accelerator sensor 15 corresponding to the depression amount AC of the accelerator pedal 16, and determines the target vehicle speed corresponding to the depression amount AC based on the map shown in FIG. Then, in order to adjust the engagement position of the clutch 2 so that the actual vehicle speed detected by the vehicle speed sensor 14 asymptotically approaches the determined target vehicle speed, the clutch drive actuator is connected via the human output interface 10 and the clutch actuator drive circuit 26. 8 is driven and controlled. At this time, the CPU 22 determines the engine speed at that time based on the detection signal from the engine speed sensor 9. At the same time, the CPU 22 determines the input shaft rotation speed of the transmission 3 at that time based on the detection signal from the human power shaft rotation speed sensor 13. Furthermore, the CPU 22 determines the stroke amount of the rod 8a of the clutch drive actuator 8 at that time, that is, the engagement position of the clutch 2, based on the detection signal from the stroke detection sensor 11, and calculates the determined engine rotation speed and input shaft rotation. The number and stroke amount are input as feedback data for driving and controlling the clutch drive actuator 8.

Next, the operation of the forklift constructed as described above will be explained according to the flowcharts shown in FIGS. 10 and 11. In addition, in this embodiment, each flowchart is CP
It shows the control operation of U22.

First, let's talk about engine speed control during cargo handling operations.
This will be explained according to the flowchart shown in FIG.

Now, in a state where the engine 1 is started and the forklift is running, in step 101, a detection signal of the accelerator sensor 15 corresponding to the depression amount AC of the accelerator pedal 16 is manually input, and the operation amount LC of the cargo handling lever 19 is
The detection signal of the lever sensor 18 corresponding to is manually generated.

Next, the process moves to step 102, and it is determined whether the amount of depression AC of the accelerator pedal 16 is greater than the amount of operation LC of the cargo handling lever 19. That is, the throttle opening of the engine 1 instructed by the accelerator pedal 16 is the same as that of the cargo handling lever 19.
It is determined whether or not the throttle opening of the engine 1 is larger than the throttle opening of the engine 1 instructed by.

Then, if the depression amount AC of the accelerator pedal 16 is larger than the operation ILc of the cargo handling lever 19, step 10
3, the normal engine speed control processing operation is executed. That is, when the throttle opening degree for the depression amount AC is larger than the throttle opening degree for the operation 11Lc, the throttle actuator is activated to give priority to the depression amount AC of the accelerator pedal 16 and to obtain the throttle opening degree instructed by the depression amount AC. 7 is driven and controlled.

On the other hand, the amount of depression AC of the accelerator pedal 16 is
If the operation amount is less than or equal to step 9 (including when the accelerator pedal 16 is not depressed), step 104 is performed.
Then, the target opening degree ps for the operation amount LC of the cargo handling lever 19 is determined. That is, when the throttle opening degree with respect to the operation amount LC is greater than or equal to the throttle opening degree with respect to the depression amount AC, the target opening degree ps is determined based on the opening degree data shown in FIG. decide.

Then, the process moves to step 105 to determine whether the drive amount of the throttle actuator 7 has reached the determined target opening PS, that is, whether the step motor constituting the throttle actuator 7 has been driven by the number of steps relative to the target opening PS. Determine whether

Target opening PS of throttle actuator 7 determined
If it is determined that the throttle actuator 7 has not been driven by an amount corresponding to ps, the process moves to step 106, and the throttle actuator 7 is controlled to be driven at a predetermined speed in order to immediately increase the throttle opening to the target opening ps. In this embodiment, the throttle actuator 7 is driven and controlled at a speed of 16 steps per 32 m5ec. As a result, the engine speed suddenly rises as shown from time tO to t1 in FIG.

Thereafter, the process jumps from step 106 to step 101 and executes the processing operations from step 101 to step 105 again.

If it is determined in step 105 that the drive amount of the throttle actuator has reached the determined target opening PS, the process moves to step 107, and the operation amount LC of the cargo handling lever 19 at that time is determined. Determine target rotation speed PN. That is, operation 1 is performed based on the rotational speed data shown in FIG. 3, which is stored in advance in the program memory 23.
Determine the target rotation speed PN for 1Lc.

Next, the process moves to step 108, where the well-known PID ff
The engine speed is controlled by dl'4B. This PID control calculates the rotational speed deviation e between the actual engine rotational speed corresponding to the detection signal of the engine rotational speed sensor 9 and the determined target rotational speed PN, and calculates the PID of the engine rotational speed based on the deviation e. The control amount ΔU (in this case, the throttle opening, that is, the value converted to the number of control steps of the throttle actuator tough) is calculated based on the following formula.

ΔU=KP ・e+K [・Δe +KD ・Δ2e where KP is a proportional constant, Kl is an integral constant, and KD is a differential constant.

Next, the process moves to step 109, and the calculated PID
Based on the control B amount ΔU, the throttle actuator 7 is drive-controlled to control the throttle opening of the engine 1 so that the actual engine speed converges to the target speed PN, that is, so that the speed deviation e converges to zero. Adjust.

Next, the process proceeds to step 110, where the detection signal of the lever sensor 18 corresponding to the operation ILc of the cargo handling lever 19 is input, and the process further proceeds to step 111, where it is determined whether or not the operation amount LC of the cargo handling lever 19 has changed. Discern. That is, the operation amount LC of the cargo handling lever 19 input this time is the same as that of the previous step 1.
It is determined whether the operation amount LC is different from the input operation amount LC at step 01.

Then, if the operation 1iLc of the cargo handling lever 19 has not changed, the process returns to step 108 and steps 108-
The processing operation of engine rotation speed control by PID control in step 111 is repeated. As a result, the engine rotation speed is smoothly and quickly converged to the target rotation speed PN, as shown at time t1 to t2 in FIG. 4. That is, time t
Following the rapid rise of the engine speed at o-tl, the engine speed can be reliably converged to the target rotation speed PN by PID control.

On the other hand, if the operating amount LC of the cargo handling lever 19 has changed, that is, if the operating amount LC of the cargo handling lever 19 has changed, the process jumps from step 111 to step 102 and repeats the processing operations from step 102 to step 111. Then, the same engine speed control as described above is executed so that the target rotation speed PH corresponds to the changed manipulated variable LC.

As described above, in the engine rotation speed control of this embodiment, the engine rotation speed is controlled according to the operation amount LC of the cargo handling lever 19, so that the engine output required for cargo handling work is controlled appropriately.
That is, an appropriate engine speed can be easily and reliably obtained only by operating the cargo handling lever 19 without depressing the accelerator pedal 16. Moreover, when the cargo handling lever 19 is operated, the throttle opening degree corresponding to the manipulated variable LC is immediately increased with good responsiveness, and then the engine speed is smoothly and quickly converged to the engine speed corresponding to the manipulated variable LC by PID control. The engine speed corresponding to the LC can be quickly obtained, the responsiveness and operability of cargo handling operations can be improved, and the cargo handling operations can be speeded up.

Next, speed control of the forklift will be explained according to the flowchart of FIG. 11.

Now, in a state where cargo handling work is being performed by operating the cargo handling lever 19 as described above, in step 201 it is determined whether or not the accelerator pedal 16 is being depressed to instruct the forklift to travel. That is, it is determined whether or not there is a detection signal from the accelerator sensor 15.

If the accelerator pedal 16 is not depressed, it is assumed that the forklift is not instructed to run, and the process proceeds to step 202, in which the clutch drive actuator 8 is controlled to completely disengage the clutch 2, and processing is performed. end.

On the other hand, if the accelerator pedal 16 is depressed,
Proceeding to step 203, it is determined whether the clutch 2 is connected and in a static friction state. That is, based on the detection signals of the engine rotation speed sensor 9 and the input shaft rotation speed sensor 13, it is determined whether the engine rotation speed and the human power shaft rotation speed are substantially the same rotation speed.

If the clutch 2 is in a static friction state, the process moves to step 204, where the clutch 2 is moved to the learning point S1 where torque transmission from the engine 1 to the transmission 3 begins. The drive actuator 8 is driven and controlled, and the process ends. On the other hand, if the clutch 2 is not in a static friction state, the process moves to step 205;
A detection signal from the accelerator sensor 15 corresponding to the depression amount AC of the accelerator pedal 16 is input, and a target vehicle speed corresponding to the depression amount IAc is determined based on vehicle speed data shown as a map in FIG. The process then proceeds to step 206, where the actual vehicle speed is determined based on the detection signal of the vehicle speed sensor 14, and the process further proceeds to step 207, where the vehicle speed deviation between the target vehicle speed and the actual vehicle speed is calculated.

Subsequently, the process moves to step 208, and it is determined whether the vehicle speed deviation is larger than necessary. That is, it is determined whether the vehicle speed deviation is within the control region indicated by diagonal lines in FIG.

If the vehicle speed deviation is larger than necessary, the process moves to step 209, and the engine speed and input shaft speed at that time are determined based on the detection signals of the engine speed sensor 9 and the input shaft speed sensor 13. , a torque transmission point S2 and a learning point S1 where the engagement position of the clutch 2 is on the disengaged side from the torque transmission point S2 shown in FIG. 6 based on both rotational speeds.
Determine whether or not there is a difference between the two. That is, it is determined whether the clutch 2 is in the connected position where the engine speed slightly exceeds the input shaft speed.

If the engagement position of the clutch 2 is not on the disengaged side of the torque transmission point S2, that is, if it is on the engagement side of the torque transmission point S2, the process moves to step 210, and this time the engagement position of the clutch 2 is the sixth Torque transmission point S2 and static friction transition point S3, which are on the cutting side of static friction transition point S3 shown in the figure.
Determine whether or not there is a difference between the two. That is, as shown in FIG. 6, it is determined whether the clutch 2 is at an intermediate position between the fully connected point S4, at which the clutch 2 is fully connected, and the learning point S1, and is at a position where static friction is likely to occur. .

If the connected position of the clutch 2 is not on the disengaged side of the static friction transition point S3, that is, if it is on the connected side of the static friction transition point S3, the process moves to step 211 to set the drive amount of the clutch 2 to zero. At that point, the drive of the clutch drive actuator 8 is stopped. Furthermore, the process moves to step 212, and the target engagement position of the clutch 2 is set at the static friction transition point S3.

Subsequently, the process moves to step 213, and it is again determined whether the engaged position of the clutch 2 is on the disengaged side of the static friction transition point S3. That is, as shown in FIG. 6, it is determined whether or not the area is above the level of the static friction transition point S3.

If the engagement position of the clutch 2 is not on the disengaged side than the static friction transition point S3, the process moves to step 214, and the clutch drive actuator 8 is activated to set the target engagement position of the clutch 2 to the static friction transition point S3. Drive control and end the process. On the other hand, in step 213, if the engaged position of the clutch 2 is on the disengaged side of the static friction transition point S3, the process ends.

If the vehicle speed deviation is not larger than necessary in step 208, the process proceeds to step 215, where another vehicle speed control process is executed to control the engagement position of the clutch 2 to approach the static friction transition point S3, and then the process proceeds to step 215. 213 jump and execute the processing operations of steps 213 and 214;
Finish the process.

Furthermore, in step 209, if the engagement position of the clutch 2 is on the disengaged side of the torque transmission point S2, the process moves to step 216. In step 216, when the vehicle speed deviation between the target vehicle speed and the actual vehicle speed is large, the connection speed of the clutch 2 is increased so that the target vehicle speed is reached early, or as the vehicle speed deviation becomes smaller, the connection speed of the clutch 2 is increased. In order to slow down the vehicle speed and gradually approach the target vehicle speed, the amount of engagement of the clutch 2 is periodically controlled. That is, based on the connection amount data shown in the map in FIG. 7, the connection amount of the clutch 2, that is, the connection speed of the clutch 2 is controlled for each control period (95 m5ec in this embodiment) for vehicle speed deviation, and then step 213 hedge jump is performed. and step 21
3,214 processing operations are executed, and the processing ends.

Further, in step 210, if the engaged position of the clutch 2 is on the disengaged side of the static friction transition point S3, the process moves to step 217. In step 217, the number of times the clutch 2 is connected is controlled in consideration of the fact that the transmission torque in the clutch 2 increases. That is, based on the interval data shown in the map in FIG. 8, the periodic interval for driving the clutch 2 by the minimum amount of engagement is set in the first to fourth control periods in response to the vehicle speed deviation at that time. In other words, as shown in Fig. 8, if the vehicle speed deviation is large, clutch 2 is driven by the minimum amount of engagement in each control cycle, and if the vehicle speed deviation is small, the clutch 2 is driven by the minimum engagement amount in each control cycle. 2 is driven by the minimum connection amount.

This clutch is used to deal with the fact that if the clutch 2 is stopped at the torque transmission point S2, the transmitted torque at the torque transmission point S2 will not be constant, and the vehicle speed may not increase. This is the second control.

After that, step 213 hedge jump, step 213
, 214 are executed, and the process ends.

In the speed control of this embodiment as described above, when the cargo handling lever 19 is operated and cargo handling work is performed, the engagement position of the clutch 2 is changed from the learning point St to the learning point St as shown by diagonal lines in FIG. It is adjusted in a half-connected state within the area of the static friction transition point S3, and a desired traveling speed, that is, a desired vehicle speed, can be obtained according to the depression amount AC of the accelerator pedal 16.

Moreover, since the amount of engagement of the clutch 2 is controlled periodically according to the engagement position of the clutch 2 in the region from the learning point si to the static friction transition point S3, and the number of engagements of the clutch 2 is controlled, the curve shown in FIG. As shown in , it is possible to gradually move the clutch 2 toward the engagement side, and in the process of increasing the vehicle speed to the target vehicle speed, the shock of engagement of the clutch 2 can be alleviated, and smooth vehicle speed control can be performed. .

Therefore, when the cargo handling speed is increased while maintaining the travel speed at a very low speed, that is, when the cargo handling lever 1 is
9, the output of the engine 1 is increased while the traveling speed is maintained at a very low speed. This can be done simply by operating the accelerator pedal 16. Therefore,
The inching pedal that is provided on a conventional forklift and used during cargo handling operations can be omitted, and the operability of cargo handling operations can be improved. That is, in this embodiment, the running speed of the forklift during cargo handling work can be easily controlled only by operating the cargo handling lever 19 and the accelerator pedal 16.

Note that this invention is not limited to the above embodiments,
The present invention can be implemented as follows by changing a part of the structure as appropriate without departing from the spirit of the invention.

(1) In the above embodiment, the amount of connection of the dry single-plate clutch 2 is determined based on the amount of connection data shown in the map in FIG. In addition to periodically controlling the 8th
Although the structure is configured to control the number of times the connection slight movement of the clutch 2 is controlled based on the interval data shown in the map in the figure, the connection amount of the clutch 2 may be controlled periodically based on a map other than that shown in The number of times the clutch 2 is slightly engaged may be controlled.

(2) In the embodiment described above, the accelerator pedal 16 was provided as the accelerator operating means, but another operating means such as an accelerator lever may be provided.

(3) In the above embodiment, a cargo handling lever 19 corresponding to a lift lever was provided as a cargo handling operation means, but a cargo handling lever corresponding to a tilt lever or a reach lever, or other cargo handling operation means may be provided. .

(4) In the above embodiment, in the engine rotation speed control during cargo handling operations, the PID is used to converge the engine rotation speed to the target rotation speed PN after controlling the throttle opening.
However, after controlling the throttle opening, a control other than PID control may be adopted to converge the engine speed to the target rotational speed PN, or the throttle opening may be controlled. Alternatively, a configuration may be adopted in which a predetermined control such as PID control is adopted from the beginning to converge the engine speed to the target rotation speed PN.

(5) In the above embodiments, a forklift is used, but the invention may be applied to a cargo handling vehicle other than a forklift.

[Effects of the Invention] As detailed above, according to the present invention, the engine speed can be increased based on the operation of the operating means such as the cargo handling lever for cargo handling operations, and the engine speed can be increased by This provides an excellent effect in that the fluctuation in the traveling speed based on the driving speed can be smoothly asymptotic to the traveling speed corresponding to the operation amount of the operating means such as the accelerator pedal without any shock.

[Brief explanation of the drawing]

1 to 11 are drawings showing an embodiment embodying the present invention, in which FIG. 1 shows the drive system mechanism and electrical configuration of a forklift, and FIG. Map showing the relationship between throttle opening and operation amount, 3rd
The figure is a map showing the relationship between the engine speed and the amount of operation of the cargo handling lever, Figure 4 is a graph explaining the change in engine speed during control execution, and Figure 5 is a map showing the relationship between the target vehicle speed and the amount of depression of the accelerator pedal. 6 is a graph showing the transition of clutch stroke amount, FIGS. 7 and 8 are maps showing clutch control with respect to vehicle speed deviation, and FIG. 9 is a graph explaining the relationship between vehicle speed deviation and target vehicle speed. FIG. 10 is a flowchart for explaining engine speed control, and FIG. 11 is a flowchart for explaining speed control. In the figure, 1 is an engine, 2 is a dry single-plate clutch, 3 is a transmission, 7 is a throttle actuator as a throttle opening adjustment means, 8 is a clutch drive actuator as a clutch drive means, and 14 is a vehicle speed detection means. 15 is an accelerator sensor as an accelerator operation amount detection means; 16 is an accelerator pedal as an accelerator operation means; 18 is a lever sensor as a cargo handling operation amount detection means; 19 is a cargo handling lever as a cargo handling operation means; 22 is a vehicle speed deviation calculation means, throttle/clutch control means, first
and a CPU as a second clutch control means, and a program memory 23 as a vehicle speed data storage means, a connection amount data storage means, and an interval data storage means. Patent applicant Toyota Industries Corporation Toyota Central Research Laboratory

Claims (1)

[Scope of Claims] 1. An engine throttle opening adjustment means, a clutch drive means for adjusting the connection state of a clutch that turns on and off the output from the engine to the transmission, and a vehicle speed detection means for detecting the running speed of the vehicle. an accelerator operation amount detection means for detecting the operation amount of the accelerator operation means operated to instruct the traveling speed; and a cargo handling operation amount detecting means for detecting the operation amount of the cargo handling operation means operated for carrying out cargo handling work. A cargo handling vehicle comprising: a vehicle speed data storage means that stores in advance a vehicle speed corresponding to the operation amount of the accelerator operation means as vehicle speed data; and a target vehicle speed corresponding to the operation amount detected by the accelerator operation amount detection means. vehicle speed deviation calculation means for calculating a vehicle speed deviation between the target vehicle speed determined based on the data and the actual vehicle speed detected by the vehicle speed detection means; and connection of the clutch per unit time in response to the magnitude of the vehicle speed deviation. connection amount data storage means that stores the amount in advance as connection amount data; and interval data storage means that stores in advance as interval data a periodic interval at which the clutch is slightly moved in connection with respect to the magnitude of the vehicle speed deviation. When it is determined that the cargo handling operation means has been operated based on the detection by the cargo handling operation amount detection means, the throttle opening degree adjusting means is drive-controlled to increase the throttle opening degree, and the clutch is moved to the disengaged side. throttle/clutch control means for driving and controlling the clutch drive means to once return the clutch drive means; and after the control by the throttle/clutch control means is performed, the clutch is brought into a predetermined half-connection state in order to bring the actual vehicle speed asymptotically close to the target vehicle speed. A first step that determines the amount of engagement of the clutch per unit time with respect to the magnitude of the vehicle speed deviation based on the amount of engagement data, and controls drive of the clutch drive means in accordance with the determined amount of engagement. and after the control of the first clutch control means is performed, the clutch is connected and slightly moved in response to the magnitude of the vehicle speed deviation at that time in order to bring the actual vehicle speed closer to the target vehicle speed. A traveling speed control device for a cargo handling vehicle, comprising: second clutch control means that determines a cycle interval based on the interval data, and controls drive of the clutch drive means according to the determined cycle interval.