JP2009287657A - Working vehicle - Google Patents

Abstract

An object of the present invention is to provide a traveling vehicle in which a hydrostatic continuously variable transmission is operated not by a mechanical interlocking mechanism but by an electronic control mechanism so that the hydrostatic continuously variable transmission can always be operated accurately.
A rotation angle of a trunnion shaft 8a of a hydrostatic continuously variable transmission 8 that outputs engine power by adjusting a rotation angle is determined by a hydraulic cylinder 6 while a stroke length of a piston rod 6a is determined by a hydraulic cylinder 6. When the pedal sensor 3s detects the neutral position when the pedal depression position is switched between the pedal 1a and the reverse pedal 1b, the forward pedal is detected by the pedal sensor 3s after a predetermined time, and the trunnion shaft 8a remains at the neutral position for a predetermined time. Control is performed to turn the trunnion shaft 8a according to the position of 1a or the reverse pedal 1b. Even when the pedal is quickly switched between the forward pedal 1a and the reverse pedal 1b, the shift shock does not occur so much that the operator's body is shaken and the feeling is not deteriorated. Deterioration can be prevented.
[Selection] Figure 5

Description

  The present invention relates to a work vehicle such as a tractor for agriculture, construction, transportation, etc. having a transmission comprising a hydrostatic continuously variable transmission and a meshing transmission.

Conventionally, in a work vehicle such as a tractor, a movable swash plate of a variable displacement hydraulic pump of a hydrostatic continuously variable transmission as a transmission system of a main transmission is interlocked with a main transmission lever and the main transmission lever is There is known a speed change method in which the output rotational speed is changed by changing the discharge amount from the hydraulic pump by moving. This hydrostatic continuously variable transmission is a system in which a trunnion shaft is rotated in a direction in which the vehicle moves forward or backward by stepping on a forward pedal and a reverse pedal.
JP 2007-2205090 A

  The work vehicle described in Patent Document 1 is configured to rotate the trunnion shaft of the hydrostatic continuously variable transmission in the direction of moving the vehicle forward or backward by stepping on the forward pedal and the reverse pedal, respectively. It is set when the forward pedal and reverse pedal are not depressed.

However, when the forward pedal (reverse pedal) is pressed down to the reverse pedal (forward pedal) quickly, the trunnion shaft passes through the neutral position all at once.
An object of the present invention is to provide a traveling vehicle in which the operation of a hydrostatic continuously variable transmission is performed not by a mechanical interlocking mechanism but by an electronic control mechanism, and in addition, the hydrostatic continuously variable transmission without shift shock can be operated. That is.

  The invention described in claim 1 includes an engine, a hydrostatic continuously variable transmission (8) having a trunnion shaft (8a) for outputting the power of the engine by adjusting the rotation angle of a swash plate, and a hydrostatic type A trunnion shaft rotating hydraulic cylinder (6) for determining the rotation angle of the trunnion shaft (8a) of the continuously variable transmission (8) by the stroke length of the piston rod (6a), and the trunnion shaft rotating hydraulic cylinder (6) A stroke length detection sensor (7s) for detecting the stroke length of the piston rod (6a), a forward pedal (1a) which is depressed when moving forward, a reverse pedal (1b) which is depressed when moving backward, a forward pedal (1a) and a reverse pedal ( Corresponds to the pedal sensor (3s) that detects the depression position of 1b) and the depression position of the forward pedal (1a) or the reverse pedal (1b) that is detected by the pedal sensor (3s) The rotation angle of the trunnion shaft (8a) is adjusted by the stroke of the piston rod (6a) of the trunnion shaft rotation hydraulic cylinder (6), and the forward pedal (1a) and the reverse pedal (1b) are adjusted by the pedal sensor (3s). When the pedal sensor (3s) detects the neutral position at the time of switching the pedal depression position between the front position and the pressure position), the trunnion shaft (8a) is kept at the neutral position for a predetermined time, and then the forward movement detected by the pedal sensor (3s) after a predetermined time. It is a work vehicle provided with a control device (5) that controls to turn the trunnion shaft (8a) according to the position of the pedal (1a) or the reverse pedal (1b).

  According to the present invention, the control device (5) moves from the forward pedal (1a) to the reverse pedal (1b) or from the reverse pedal (1b) to the forward pedal (1a) quickly (from a state where the pedal on one side is depressed). When the pedal is switched, the trunnion shaft (8a) is once adjusted and held in the neutral range even if the pedal is depressed, and after a predetermined time (for example, 0. 0). After 3 seconds, the rotation angle of the trunnion shaft (8a) corresponding to the accelerator pedal sensor (7s) for detecting the forward or reverse range is set.

  According to the present invention, even when the pedal is quickly switched between the forward pedal 1a and the reverse pedal 1b, the shift shock does not significantly shake the operator's body, and the feeling does not deteriorate. It can prevent the deterioration of the durability of machine parts.

Embodiments of the present invention will be described with reference to the drawings.
A tractor, which is an example of a continuously variable work vehicle, is a transmission in which a hydrostatic continuously variable transmission is provided at a floor position of a control unit as shown in a plan view (a) and a side view (b) of FIG. 1 is mounted, and a forward pedal 1a and a reverse pedal 1b are disposed at the lateral positions thereof. The transmission 1 continuously changes the traveling power transmitted from the engine (not shown) and transmits it to the traveling wheels to adjust the traveling vehicle speed in the forward / rearward direction. The transmission 1 is controlled according to each pedal depression operation. A transmission speed control device (not shown) is provided.

  FIG. 1 is a system configuration diagram of a transmission speed control device for a continuously variable work vehicle. This transmission speed control system includes an input side for detecting the depression operation of the forward pedal 1a and the reverse pedal 1b arranged so as to be capable of being depressed, and a speed adjustment unit of the hydrostatic continuously variable transmission 8 so as to correspond to the pedal operation. Is adjusted to a target speed position, and a controller 5 that performs device control processing on the output side based on the detection signal on the input side.

  The input side of the transmission speed control system includes a forward pedal 1a and a reverse pedal 1b, rods 2a and 2b connected to a pivot 1c that is a rotation center common to the pedals 1a and 1b, and these rods 2a and 2b. Crank levers 3a, 3b that convert the forward / backward movement of the pedals into rotational movements in different directions with respect to the common rotating shaft 3c, and a pedal sensor that detects the depression position of the pedals 1a, 1b based on the rotational angles of the crank levers 3a, 3b 3 s or the like. In addition, on the input side of the transmission speed control system, a vehicle speed sensor 4a, a throttle sensor 4b for detecting the opening of an engine throttle valve corresponding to the output of an engine (not shown), and an oil for operating a hydraulic cylinder 6 are also provided. An oil temperature sensor 4c or the like for detecting the temperature can be provided, and the detection signals of the sensors 4a to 4c are input to the transmission speed control unit 5 including a digital controller or the like.

  The output side of the transmission speed control system includes a hydraulic cylinder 6 that is an actuator that expands and contracts by an electromagnetic hydraulic control valve 9, and a crank lever 7 that rotates about a support shaft 7a in response to the expansion and contraction of the piston rod 6a. A trunnion sensor 7s for detecting the rotation position of the speed adjusting portion by the trunnion shaft 8a based on the rotation angle of the crank lever 7, and a hydrostatic continuously variable transmission 8 connected from the crank lever 7 via a rod 7b. Consists of. The hydrostatic continuously variable transmission 8 is a forward / reverse hydrostatic continuously variable transmission, and the transmission speed is adjusted by the rotation angle of the trunnion shaft 8a, which is the speed adjusting portion thereof, so that the work vehicle moves forward and backward. And adjust the running speed steplessly.

  A specific configuration example on the input side of the transmission speed control unit 5 is shown in the perspective view of FIG. As shown in FIG. 2, the forward pedal 1a, the reverse pedal 1b, the pedal sensor 3s for detecting these operations, and the connecting members described below between the pedals 1a, 1b and the pedal sensor 3s are configured as a single pedal link unit. .

  As shown in the side view of FIG. 3, a hydrostatic continuously variable transmission 8 is provided inside the pedal link unit, and a forward pedal is provided at a side portion of the transmission 1 for adjusting the vehicle speed of a work vehicle such as a tractor. 1a and reverse pedal 1b are pivotally supported on a common support shaft 1c, arranged in parallel to each other in close proximity to each other, and the movements of the respective pedals 1a and 1b are transmitted to rods 2a and 2b with adjusters whose one ends are fixed to support shaft 1c. Further, the crank levers 3a and 3b having one ends connected to the other ends of the rods 2a and 2b are operated. The other ends of the crank levers 3a and 3b are connected to a common rotating shaft 3c from opposite sides, and the forward / backward movement of the rod 2a or the rod 2b is converted into rotating operations in different directions by the rotating shaft 3c. When the action arm 3e provided integrally with 3c is operated, the pedal sensor 3s interlocked therewith detects the swing angle of the rotating shaft 3c, that is, the depression amount of the forward pedal 1a and the reverse pedal 1b.

  Since the pedals 1a and 1b, the pedal sensor 3s, and the rods 2a and 2b are attached to the floor F that is mounted and supported with respect to the transmission 1, vibration from the transmission 1, that is, vibration from the airframe side is suppressed. The detection accuracy of the pedal sensor 3s is improved.

  In the unit on the input side of the pedal link unit, when one of the forward pedal 1a and the reverse pedal 1b is depressed, the rotary shaft 3c rotates via the corresponding rods 2a and 2b and the crank levers 3a and 3b. The pedal sensor 3s detects the rotation angle of the rotating shaft 3c corresponding to the pedal depression operation via the action arm 3e of the rotating shaft 3c. Further, when the other one of the forward pedal 1a and the reverse pedal 1b is depressed, the corresponding crank levers 3a and 3b rotate in the direction opposite to the rotational direction of the rotary shaft 3c, and as a result, the pedal sensor 3s reverses the direction. Is detected.

  In the output side unit of the pedal link unit, as shown in the side view of FIG. 4, a hydraulic cylinder 6 is disposed along the side surface of the transmission 1, and a crank lever 7 connected to the piston rod 6a is connected to a support shaft 7a. One end of a trunnion sensor 7s that is pivotally supported by the lever and detects the swing angle of the crank lever 7 is locked to the lever 7. One end of a rod 7b is connected to the crank lever 7, and a trunnion arm 8b which is a crank lever integral with the trunnion shaft 8a of the transmission 1 is connected to the other end of the rod 7b.

  Therefore, the stroke length detection sensor 7s can detect the stroke length of the piston rod 6a of the trunnion shaft rotation hydraulic cylinder 6, and the trunnion shaft 8a rotates according to the detection value of the detection sensor 7s, and the pedals 1a and 1b. Is output from the hydrostatic continuously variable transmission 8.

The units on the output side of these pedal link units are attached to the side surface of the transmission 1.
Thus, the output side unit is arranged in parallel with the input side unit. Further, a cam 8c is formed on the trunnion arm 8b, and a neutral arm 8e acting on the cam 8c is attached by a neutral spring 8d so as to return the trunnion arm 8b to the neutral position.

  Due to the unit configuration on the output side of the pedal link unit, when the piston rod 6a of the hydraulic cylinder 6 that is hydraulically controlled moves forward and backward, the trunnion shaft 8a integrated with the trunnion arm 8b is rotated via the crank lever 7 and rod 7b. A swash plate of a variable hydraulic motor (not shown) of a hydrostatic continuously variable transmission 8 installed in the transmission 1 is rotated to adjust a transmission speed, and a trunnion sensor 7s for detecting an adjustment position of the trunnion shaft 8a. The required speed can be adjusted by controlling the expansion and contraction of the hydraulic cylinder 6 based on the signal. Further, when the control hydraulic pressure of the hydraulic cylinder 6 is released, the trunnion arm 8b is returned to a predetermined neutral position by the cam 8c receiving the acting force of the neutral arm 8e, and the vehicle body travel is stopped.

  When the pedal sensor 3s detects the depression operation of the forward pedal 1a and the reverse pedal 1b, the transmission speed control unit 5 determines the target speed position of the trunnion shaft 8a according to the detection signal of the pedal sensor 3s, and the trunnion shaft 8a is the target. The hydraulic cylinder 6 is controlled by the electromagnetic hydraulic pressure switching (control) valve 9 based on the signal from the trunnion sensor 7s until it becomes equal to the speed position. As a result, the traveling vehicle speed of the aircraft can be adjusted according to the pedal operation.

  The transmission speed control unit 5 detects the individual stepping operation amounts of the forward pedals 1a and 1b via the common pedal sensor 3s according to the configuration on the detection side, so that the two pedals 1a and 1b according to the individual pedal specifications are detected. The transmission speed control device for adjusting the vehicle speed in a stepless manner according to the stepping amount of the vehicle can be simplified to reduce manufacturing cost and maintenance load while ensuring common operability.

  In this embodiment, as shown in the flowchart of FIG. 5, when the operator quickly (quickly) switches from the forward pedal 1a to the reverse pedal 1b or from the reverse pedal 1b to the forward pedal 1a, the trunnion shaft 8a is once neutralized. It is configured so that the rotation angle of the trunnion arm 8b corresponding to the accelerator pedal sensor 3s for detecting the forward or reverse range is reached after a predetermined time (for example, after 0.3 seconds). Furthermore, it can be adjusted stepwise by repeating turning on and off of the output to the hydraulic cylinder 6 or can be adjusted at a slow speed by using pulse output.

  The “adjustment in stages” means that the electric signal to the valve that operates the hydraulic cylinder is turned on and off to position the target position in stages, and the target position is output at a slow speed by outputting pulses. You may make it position to.

  If the trunnion arm 8b is not kept in the neutral range for a certain period of time when the pedals 1a and 1b are quickly switched, the shift shock increases, the operator's body is shaken, and the operation feeling is poor. Become. Moreover, since a load is applied also to a machine part on it, durability also worsens.

  Occasionally, an operator may turn off the engine key while driving to apply a brake to stop the vehicle. In this case, the next time the engine key is turned on, the accelerator pedal sensor 3s does not detect the neutral range against the operator's intention, so the hydraulic cylinder 6 is adjusted to the forward side or the reverse side and the vehicle moves. There is a risk that.

  Therefore, when the accelerator pedal sensor 3s, which detects the forward or reverse range only once when the engine key is turned on, does not detect the neutral range, the buzzer continuously notifies and the trunnion shaft 8a is activated. The hydraulic cylinder 6 is operated to return the detection position of the sensor 3s to the neutral position. Further, the subsequent start condition of the operation control of the trunnion shaft 8a is configured such that the accelerator pedal sensor 3s detects the forward or reverse range. Thus, the safety of the trunnion control can be improved as compared with the conventional case.

In recent years, there have been many cases of vehicle theft. In this embodiment, the front switch panel in the driver's seat of the tractor is designed as shown in the plan view of FIG.
This switch panel has software that the controller 5 is activated only when a specific switch among a number of switches is sequentially pressed after the engine is started. That is, each control is executed when the sensitivity switch or the horizontal changeover switch is pressed in a specific order.

  Therefore, the controller 5 is activated only after the switches are pushed in the order determined by each of the switches, thereby preventing theft. Further, if the switch pressing order can be changed before the engine is turned off, theft (riding and escape) is further prevented. This configuration also has the advantage that it is not necessary to provide a dedicated device for theft device.

  Further, when the front switch panel shown in FIG. 6 is removed, the controller 5 can be prevented from being stolen by setting a function that does not start. The setting of the function for preventing the controller 5 from being activated is, for example, when the front switch panel is removed while a specific switch in the front switch panel is pressed. Further, a specific switch on the side of the machine other than the front switch panel may be used.

When the front switch panel is removed, the controller 5 may be configured to determine whether to enable or disable the configuration that does not start.
In this case, the controller 5 is activated when the front switch panel is removed without pressing the specific switch. Thereby, even if the front switch panel is removed, the control controller 5 can be activated when, for example, it is desired to move the machine body, so that the operator's intention can be reflected. In addition, since a specific switch is shared with a switch having another function, the configuration is inexpensive without increasing the number of switches.

Further, when the various functions for security are set, the security function is further enhanced by adopting a configuration in which it is impossible to set the function to invalid.
For example, when an engine key is inserted, the security function is activated, and an input (security release) that disables this security function cannot be set. However, when the engine key is activated and the security function is activated, a specific switch An invalid input of the security function can be set so that the security function can be canceled by operating the determined switch or the specific switch determined at the time of factory shipment as a security release switch.

  It may be configured such that setting by such a security function switch can be set by an external communication device. In this case, if the setting by the switch is not disabled in the external communication device while the security function is set, the safety is jeopardized.

  In order to set the security function again after canceling the security function, the main switch (engine) key is removed, the main switch key is inserted again, and it is possible when the engine is started. It is no longer necessary to release the security function.

1 is a system configuration diagram of a transmission speed control device for a continuously variable work vehicle of a traveling vehicle according to an embodiment of the present invention. It is a perspective view which shows the specific structural example of the input side of the transmission speed control part of the traveling vehicle of FIG. It is a side view of the pedal link unit of the traveling vehicle of FIG. FIG. 4 is an operation assist structure diagram by a hydraulic cylinder of a hydrostatic continuously variable transmission in the pedal link unit of FIG. 3. 2 is a flowchart of rotation control of a trunnion shaft when a forward pedal and a reverse pedal of the traveling vehicle in FIG. 1 are switched. It is a top view of the front switch panel in the driver's seat of the traveling vehicle of FIG. FIG. 8 is a plan view (FIG. 7A) and a side view (FIG. 7B) of a tractor that is an example of a continuously variable work vehicle.

Explanation of symbols

1 Transmission 1a Forward pedal 1b Reverse pedal 1c Support shaft 2a, 2b Rod 5 Controller (Transmission speed control unit)
3a, 3b Crank lever 3c Rotating shaft 3e Action arm 3s Pedal sensor 4a Vehicle speed sensor 4b Throttle sensor 4c Oil temperature sensor 6 Hydraulic cylinder 6a Piston rod 7 Crank lever 7a Support shaft 7b Rod 7s Trunnion sensor 8 Hydrostatic continuously variable transmission 8a Trunnion shaft 8b Trunnion arm 8c Cam 8d Neutral spring 8e Neutral arm

Claims (1)

Engine,
A hydrostatic continuously variable transmission (8) having a trunnion shaft (8a) that outputs the power of the engine by adjusting the rotation angle of the swash plate;
A trunnion shaft rotating hydraulic cylinder (6) for determining the rotation angle of the trunnion shaft (8a) of the hydrostatic continuously variable transmission (8) by the stroke length of the piston rod (6a);
A stroke length detection sensor (7s) for detecting the stroke length of the piston rod (6a) of the trunnion shaft rotating hydraulic cylinder (6);
A forward pedal (1a) that is depressed when moving forward, and a reverse pedal (1b) that is depressed when moving backward,
A pedal sensor (3s) for detecting the depression positions of the forward pedal (1a) and the reverse pedal (1b);
The trunnion shaft (8a) is caused by the stroke of the piston rod (6a) of the hydraulic cylinder (6) for turning the trunnion shaft corresponding to the stepping position of the forward pedal (1a) or the reverse pedal (1b) detected by the pedal sensor (3s). When the pedal sensor (3s) detects the neutral position when the pedal depression position is switched between the forward pedal (1a) and the reverse pedal (1b) by the pedal sensor (3s), The rotation angle of the trunnion shaft (8a) according to the position of the forward pedal (1a) or the reverse pedal (1b) detected by the pedal sensor (3s) after a predetermined time after the trunnion shaft (8a) is kept at the neutral position for a predetermined time. A work vehicle comprising a control device (5) for performing control.

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