JP2005036921A - Drive mechanism of working vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a working vehicle capable of reducing rapid torque fluctuation transmitted to a drive mechanism when a clutch is engaged with the drive mechanism of a working vehicle and being excellent in safety and operation. <P>SOLUTION: The drive mechanism of a working vehicle comprises a major speed change lever sensor 111, a direction switch 102, a trunnion axis angle sensor 64, a clutch switch 120, and a running control controller 110 which is a control means for controlling a speed change gear on the basis of detected values. When the clutch is disengaged, the speed change gear is controlled to lead into a neutral standstill state. When the clutch is switched from the disengaged state to an engaged state in the drive mechanism, the speed change means is gradually accelerated at a beginning stage up to speed at a targeted speed change position if switching of the clutch is detected. Subsequently, speed changing rate is increased, and the speed changing rate is controlled to reduce before reaching to the speed at the targeted speed change position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a drive device for a work vehicle, and more particularly, a control for reducing shock that occurs when a clutch is switched between “disengagement” and “contact” in a traveling vehicle equipped with a continuously variable transmission that can be automatically controlled. It relates to means.

  As a transmission method of the main transmission device in a work vehicle such as a tractor, a gear is selected by sliding a toothed slider, or a gear with a different gear ratio that is always meshed using a hydraulic clutch is selected. Those that transmit power from the engine are known. In such a main transmission, a clutch operating part is provided in the middle of the transmission means for transmitting the engine rotation, and when changing speed and changing the direction, the clutch operating part is operated to transmit the engine rotation to the mission side. There is no configuration.

  On the other hand, a drive equipped with a continuously variable transmission that allows an operator to perform a shift without operating a clutch by a hydraulic device, a pulley width transmission, or the like during transmission, such as a transmission of the HST type or CVT type. Devices are also known. For example, a transmission for a hydraulically driven vehicle proposed in Patent Document 1 includes an HST transmission having a variable displacement hydraulic pump and a fixed displacement hydraulic motor. The movable swash plate is connected and interlocked with the main speed change lever, and by rotating the main speed change lever, the amount of discharge from the hydraulic pump is changed to change the output rotation speed so that traveling control can be performed. (See Patent Document 1).

JP 2002-250437 A

  However, in the conventional gear selection type, so-called mechanical transmission, when the clutch is engaged in the high speed range, the engine rotation is suddenly transmitted to the axle, which may shock the operator or the work vehicle body. Therefore, when an operator performs a clutch operation, an operation (for example, a so-called “half-clutch”) that gradually connects engine rotation to a traveling axle is required, and the operation operation of such a work vehicle is troublesome. It was.

  Further, in the continuously variable transmission of the HST type or the like, when automatic shift such as speed switching or traveling direction switching is performed in the clutch “disengaged” state, the clutch is disengaged due to the control delay of the continuously variable transmission. When connected, the vehicle sometimes began to run in a direction different from the direction speed operated by the operator. Therefore, the confirmation work at the time of stopping / starting the work vehicle is troublesome.

  Further, the work vehicle including the transmission described in Patent Document 1 has the same problem. That is, a work vehicle such as a tractor may repeatedly travel forward and backward in a field, but on the other hand, in a corner or the like of the field, the traveling direction is changed after the vehicle body is temporarily stopped. It may be preferable. In addition, depending on the state of the field and the type of work, low speed operation or high speed operation may be required, and in such a case, smooth work is hindered by complicated clutch operation.

  Therefore, the present invention relates to a drive device for a work vehicle, which solves the above-described conventional problems, and reduces sudden torque vibration transmitted to the drive device when the clutch is engaged, and allows simple driving. An object of the present invention is to propose a drive device that realizes the operation.

  The problem to be solved by the present invention is as described above. Next, means for solving the problem will be described.

  That is, in claim 1, the means for detecting the rotational position of the main transmission operation tool, the means for detecting the rotational position of the forward / reverse switching operation tool, the means for detecting the transmission position of the transmission, A drive device for a work vehicle comprising: means for detecting connection / disconnection; and control means for controlling the transmission based on the detected value. The control means neutralizes the transmission when the clutch is “disconnected”. This is a stop state.

  According to another aspect of the present invention, means for detecting the rotational position of the main speed change lever, means for detecting the rotational position of the forward / reverse switching lever, means for detecting the speed change position of the transmission, and detection of clutch engagement / disconnection are detected. And a control means for controlling the transmission based on the detected value. The drive means for the work vehicle includes a transmission means when the clutch is changed from “disengaged” to “clutch”. Is gradually accelerated at the initial stage of reaching the speed of the target shift position, and then the speed of change is increased.

  According to a third aspect of the invention, there is provided a means for detecting the vehicle speed according to the first or second aspect, wherein the control means determines the acceleration of the work vehicle from the change in the vehicle speed when the clutch is changed from "disengaged" to "clutch". By calculating, the speed is changed so that the acceleration becomes a certain value or less.

  According to a fourth aspect of the present invention, the clutch switch according to the first or second aspect is provided with a means for detecting connection / disconnection of the clutch and a means for connecting / disconnecting the starter circuit to the clutch operation section. However, it also serves as both means for detecting connection / disconnection of the clutch and means for connecting / disconnecting the starter circuit.

  As effects of the present invention, the following effects can be obtained.

  That is, as shown in claim 1, means for detecting the rotational position of the main transmission operating tool, means for detecting the rotational position of the forward / reverse switching operation tool, means for detecting the gear shifting position of the transmission, In a drive device for a work vehicle, comprising: means for detecting engagement / disengagement of a clutch; and control means for controlling the transmission based on the detected value. When the clutch is “disengaged”, the control means Since the vehicle is set in a neutral stop state, it is possible to prevent sudden start and travel in an unintended direction due to control delay, and improve the safety and operability of traveling and stopping the work vehicle.

  According to another aspect of the present invention, means for detecting the rotational position of the main transmission lever, means for detecting the rotational position of the forward / reverse switching lever, means for detecting the transmission position of the transmission, and connection / disconnection of the clutch And a control means for controlling the transmission on the basis of the detected value, the drive means for the work vehicle comprises a control means for changing the clutch from "disengaged" to "clutch" The speed change means is gradually accelerated at the initial stage of reaching the speed of the target speed change position, and then the speed of change is increased. This prevents sudden start of the work vehicle and eliminates the need for complicated clutch operations such as so-called "half clutch". And can improve work efficiency.

  According to a third aspect of the present invention, in the first or second aspect, the vehicle is provided with a means for detecting the vehicle speed, and the control means changes the vehicle speed from the change of the clutch "disengagement" to the clutch "contact", thereby Since the acceleration is calculated and the speed is changed so that the acceleration is below a certain level, when the clutch is engaged, the acceleration in the traveling direction of the work vehicle is reduced and the torque vibration transmitted to the drive device is reduced. Even when the clutch is engaged in the high speed range, it is possible to prevent the engine drive from being suddenly transmitted to the axle and shocking the operator or the work vehicle main body.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the clutch operating portion includes means for detecting connection / disconnection of the clutch and means for connecting / disconnecting the starter circuit, and is disposed in the clutch operating portion. Since the clutch switch serves as both a means for detecting connection / disconnection of the clutch and a means for connecting / disconnecting the starter circuit, it is not necessary to provide a plurality of expensive switches or the like in the clutch operation section, and a structure necessary for mounting the switch is also provided. You can keep it simple.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
1 is a plan view of a tractor provided with a transmission according to the present invention, FIG. 2 is a side sectional view of a transmission case, FIG. 3 is a skeleton diagram showing a drive transmission mechanism, and FIG. 4 is a side view of a transmission section of the transmission case. FIG. 5 is a hydraulic circuit diagram, and FIG. 6 is a side view of the clutch operation unit. 7 is a control block diagram, FIG. 8 is a flowchart diagram, FIG. 9 is a flowchart diagram, and FIG. 10 is a flowchart diagram. 11 is a diagram showing the relationship between the trunnion shaft angle and time, FIG. 12 is a diagram showing the relationship between the trunnion shaft position and the trunnion shaft angle changing speed, and FIG. 13 is the relationship between the main shift lever sensor value and the target shift. FIG. 14 is a starter circuit diagram, FIG. 15 is a side view of a clutch operation unit according to another embodiment, and FIG. 16 is a starter circuit diagram according to another embodiment.

First, the schematic structure of the tractor 1 which is one Example of the hydraulic drive vehicle provided with the drive device according to the present invention will be described below.
As shown in FIG. 1, an engine 2 is arranged in a bonnet 3 at the front of the machine, the engine 2 is covered with the bonnet 3, and a handle 5 serving as steering means is provided on a dashboard 4 at the rear of the bonnet 3. Is arranged. A forward / reverse switching lever 8 comprising an accelerator lever and a forward / backward switching operation tool is projected on the side of the dashboard 4, and a seat 6 is disposed behind the handle 5. An auxiliary transmission lever 10, a PTO transmission lever 11, and a work implement lifting / lowering lever 12 are disposed in the vicinity of the seat 6, and a main transmission lever 7 is disposed on the fender 21. A portion where the seat 6 and the handle 5 are disposed is a control portion 9. The arrangement position of each lever is not limited to this, and may be in the vicinity of the control unit 9.

  A main transmission lever sensor 111 serving as means for detecting the rotation position of the main transmission operating tool is disposed at the rotation base of the main transmission lever 7, and the main transmission lever sensor 111 is connected to the travel controller 110. Yes. In addition, a direction switching switch 102 serving as a means for detecting the rotation position of the forward / reverse switching operation tool is disposed at the rotation base of the forward / reverse switching lever 8, and the direction switching switch is connected to the travel controller 110. ing.

  Front wheels 13 and 13 are supported on both sides of the front part of the machine, and rear wheels 14 and 14 are supported on both sides of the rear part. A mission case 15 is disposed below the seat 6 and a three-point link type work machine mounting device 16 for mounting various work machines is attached to the rear of the mission case 15. A PTO shaft 27 protrudes from the rear surface of the transmission case 15 so that the work machine can be driven.

Next, the drive transmission system of the tractor 1 will be described below.
As shown in FIGS. 2 and 3, a clutch 20 is disposed at the rear portion of the output shaft of the engine 2, and an HST (hydraulic continuously variable transmission) disposed in the mission case 15 via the clutch 20. Power is transmitted to the input shaft 33 of the hydraulic pump 51. The input shaft 33 extends rearward through the hydraulic pump 51 to drive the hydraulic pump 51, and power is transmitted from the input shaft 33 to the PTO shaft 27 via the PTO transmission 26. . In the vicinity of the output shaft of the engine 2, an engine speed sensor 113 serving as means for detecting the speed of the engine 2 is disposed, and the engine speed sensor 113 is connected to the travel control controller 110.

  The HST 23 includes a variable displacement hydraulic pump 51 and a fixed displacement hydraulic motor 52, and a movable swash plate 53 constituting the hydraulic pump 51 is tilted by an operation of a hydraulic cylinder 67 serving as an actuator described later. The hydraulic cylinder 67 is driven by operating the main transmission lever (HST lever) 7 or the like. In the present embodiment, the main transmission lever 7 is disposed on the fender 21, but such an arrangement is not limited to this, and may be disposed on the dashboard 4, for example.

  A subtransmission 24 is provided on the rear side of the HST 23, that is, on the downstream side of the power transmission path, and power is transmitted to the subtransmission 24 via the output shaft 25 of the hydraulic motor 52 of the HST 23. The auxiliary transmission 24 is capable of three-stage shifting by sliding the sliding gear 31. The power changed by the auxiliary transmission 24 is transmitted from a drive shaft 30 which is an output shaft of the auxiliary transmission 24 through a drive pinion 32 provided at the rear end of the drive shaft 30 to a rear wheel differential device 34. To be told.

  The rear wheel differential device 34 drives the rear wheels 14 and 14 via the left and right differential yoke shafts 35L and 35R and the final reduction mechanisms 36 and 36. The rotation speed of the rear wheel 14 is detected by an axle rotation speed sensor 112 serving as means for detecting the rotation speed of the axle. In the present embodiment, the axle rotation speed sensor 112 is configured to detect the rotation of the differential yoke shaft 35L (35R). However, the detection target is not limited to this. It is good also as a structure which detects the rotation speed of a gearwheel, the rotation speed of the axle which fixed the rear wheel 14, or the rotation speed of the drive shaft 30, etc.

  Further, a front wheel drive gear 40 is fixed on the drive shaft 30, and the power transmitted to the drive shaft 30 is transmitted from the front wheel drive gear 40 to the front wheel transmission device 29 via the two counter gears 41. It is done. The front wheel transmission device 29 includes an occlusal four-wheel drive clutch 37 and a front wheel acceleration clutch 38. When both clutches 37 and 38 are OFF, only the rear wheels 14 and 14 are driven, Operated on the road. On the other hand, when the four-wheel drive clutch 37 is turned on, the front wheels 13 and 13 and the rear wheels 14 and 14 are driven at the same speed, and are operated during work. The front wheel acceleration clutch 38 is turned on when the handle 5 is rotated more than a set angle so that the driving speed of the front wheels 13 and 13 is increased more than that of the rear wheels 14 and 14 and is driven at about twice the speed. ing.

  The power changed by the front wheel transmission device 29 is transmitted from the output shaft to the front differential device 43 in the front axle case via the transmission shaft 19, and the front differential device 43 receives the differential yoke shafts 44L and 44R on both sides. The front wheels 13 and 13 are driven via the final reduction mechanism 45.

  As shown in FIG. 4, a trunnion shaft (transmission shaft) 61 is connected to the movable swash plate 53 of the hydraulic pump 51 so as to protrude from the HST storage case 62, and a shift arm 63 is connected to the trunnion shaft 61. It is fixed. A trunnion shaft angle sensor 64 serving as means for detecting the shift position of the transmission is fixed on the HST storage case 62, and the sensor arm 64a of the trunnion shaft angle sensor 64 engages one end 63a of the shift arm 63. In addition, the rotation angle of the shift arm 63 (the trunnion shaft 61) is detected. In other words, the shift position of the HST 23 is detected by the trunnion shaft angle sensor 64. The trunnion shaft angle sensor 64 is connected to the travel controller 110.

  The configuration of the trunnion shaft angle sensor 64 is not limited to this, and may be, for example, a potentiometer, a rotary switch, a rotary encoder, or the like. Further, the mounting position of the trunnion shaft angle sensor 64 is not limited to this, and the trunnion shaft angle sensor 64 can be disposed on or around the trunnion shaft 61.

  The other end 63b of the shift arm 63 extends downward and is pivotally supported by one end 65a of the connecting link 65, and the other end 65b of the connecting link 65 extends rearward (leftward in FIG. 4). The connection arm 66 is pivotally supported at one end 66a. The other end 66b of the connecting arm 66 is pivotally supported by the tip of a piston rod 67a of a hydraulic cylinder 67 serving as an actuator, and a midway portion of the connecting arm 66 is erected on a fulcrum bracket 68 fixed to the side surface of the transmission case 15. The pin 68a is pivotally supported.

  When the piston rod 67a of the hydraulic cylinder 67 is expanded and contracted, the connection arm 66 is rotated around the pin 68a, and the connection link 65 is slid in the front-rear direction in conjunction with the rotation of the connection arm 66. The shift arm 63 is rotated around the trunnion shaft 61. The trunnion shaft 61 is rotated with the rotation of the shift arm 63, and the trunnion shaft 61 is rotated by the expansion and contraction of the piston rod 67a of the hydraulic cylinder 67, and the movable swash plate 53 of the hydraulic pump 51 of the HST 23. It is said that is controlled.

  Thus, the trunnion shaft 61 is connected to the hydraulic cylinder 67 via the connecting arm 66, the connecting link 65, and the shift arm 63 by switching and expanding / contracting the control valve 86, which will be described later, according to the control signal of the travel controller 110. Is rotated and the movable swash plate 53 is tilted. The turning angle of the trunnion shaft 61 is detected by the trunnion shaft angle sensor 64 and fed back to the travel controller 110.

Next, the hydraulic circuit of the tractor 1 will be described below.
As shown in FIG. 5, the engine 2 drives the first pump 71, the second pump 72, the charge pump 73, and the hydraulic pump 51, and the hydraulic oil in the mission case 15 is sucked through the filter, The hydraulic oil from the two pumps 72 is sent to a hydraulic cylinder for lifting and lowering the work machine and a hydraulic cylinder for horizontal control of the work machine, not shown, so that each hydraulic cylinder is driven. A shunt valve 74 is connected to the discharge side of the first pump 71, and the shunt valve 74 is a priority valve, and is connected to the HST 23 and the control hydraulic cylinder 67 in the priority shunt oil passage, The power steering control valve 75 and the power steering cylinder 76 are connected.

  A relief valve 77 and a control valve 86 for setting the control pressure of the hydraulic cylinder 67 are connected to the priority side output oil passage of the diversion valve 74. The control valve 86 includes an electromagnetic valve 78 that controls the expansion of the hydraulic cylinder 67, an electromagnetic valve 79 that controls the reduction, and an electromagnetic valve 80 that controls the amount of flow to the charge pump 73. The electromagnetic valve 80 is controlled to open and close by adjusting the duty ratio by PWM control, and controls the hydraulic pressure to the hydraulic cylinder 67 by controlling the flow rate. The electromagnetic valve 78 and the electromagnetic valve 79 are switched by an operation to be described later to control the expansion / contraction of the hydraulic cylinder 67.

  With this control, the tilt angle of the movable swash plate 53 is changed to change the discharge amount and discharge direction of the hydraulic pump 51, and the output shaft 25 of the hydraulic motor 52 is rotated forward and backward to move the tractor 1 forward and backward. You can reverse. The electromagnetic valves 78, 79, and 80 can be configured by a single electromagnetic valve.

  In the HST 23, the hydraulic pump 51 and the hydraulic motor 52 are connected by oil passages 81 and 82 to form a closed circuit, and the oil pressure of the oil passages 81 and 82 is detected in the vicinity of the oil passages 81 and 82. Pressure sensors 114 and 115 are disposed as means for performing the above operation, and the pressure sensors 114 and 115 are connected to the travel controller 110. The closed circuit is connected via a filter 83, a throttle 84, and a check valve 85 so that the pressure oil from the charge pump 73 can be replenished.

  The transmission according to the present embodiment is not limited to the HST 23. For example, a cam-type transmission, a stepped automatic transmission using a hydraulic clutch, or a CVT (Coutinously Variable Transmission) using a belt. Etc.) and other transmissions easily conceived by those skilled in the art.

Here, the configuration of the clutch operation unit 89 will be described below.
As shown in FIGS. 1 and 6, in the tractor 1 according to this embodiment, the engine 2 is mounted on a front and rear long plate-like vehicle frame 87, and steps 88 and 88 are substantially horizontal on both the left and right sides of the vehicle frame 87. It is arranged. A clutch operation part 89 is formed in the step 88 on the lower left side of the dashboard 4, and a clutch pedal 91 of the clutch operation part 89 is disposed on a bracket 90 suspended on the lower side of the vehicle frame 87. ing. A rotating shaft 92 is horizontally supported on the bracket 90 so as to be rotatable. A base 91a of the clutch pedal 91 is fixed to one end of the rotating shaft 92 so as not to be relatively rotatable. In this way, the pivot shaft 92 is disposed below the step 88 in order to pivotally support the clutch pedal 91.

  The clutch pedal 91 has a substantially base shape 91 in a side view for connecting the base portion 91a to the tread surface portion 91b, and a tread surface portion 91b for the operator to step on. A connecting portion 91c and an abutting portion 91d that protrudes rearward and downward so as to abut on a clutch switch 120, which will be described later, are supported by the bracket 90 via the rotating shaft 92. The entire clutch pedal 91 is locked.

  The rotation shaft 92 is fixedly provided with a middle portion of an arm 93 that is arranged slightly rearward in a substantially vertical direction. When the clutch pedal 91 is depressed, the arm 93 is tilted at the same time. Has been. A pin shaft 93a is formed at the upper end of the arm 93, and one end of a rod 94 is pivotally connected to the pin shaft 93a so as to be rotatable. The pin shaft 93a has a tip protruding from the rod 94 to form a protruding portion, and one end of the return spring 95 is locked in a locking hole penetrating the protruding portion. One end of the return spring 95 on one side is locked to a locking tool 98 disposed on a support stay 96 disposed on the lower side of the vehicle frame 87.

  A pin shaft 93b is formed on the lower end of the arm 93, and one end of the rod 97 is pivotally connected to the pin shaft 93b. One end of the rod 97 is connected to the clutch 20 or the like. They are connected so that they can be linked to each other. The rod 97 is slid in the front-rear direction of the tractor 1 when the arm 93 is rotated about the rotation shaft 92. In the clutch operation unit 89 according to the present embodiment, the clutch 20 and the like are disconnected when the rod 97 is moved forward.

  The support stay 96 is provided with a clutch switch 120 as means for detecting clutch engagement / disengagement, and the clutch switch 120 is connected to the travel controller 110. When the clutch pedal 91 is stepped on and the contact portion 91d is rotated, the clutch switch 120 is pressed by the pressing tool 99 disposed on the upper surface of the corresponding contact portion 91d.

  The clutch operating portion 89 is urged by the return spring 95 via the pin shaft 93a to the rear of the vehicle (rightward in FIG. 6), and in conjunction with the arm 93 via the pin shaft 93b. Thus, the clutch 20 or the like is biased in the direction of the clutch “contact”. When the clutch pedal 91 is stepped on by the operator, the clutch pedal 91 is rotated about the rotation shaft 92, and the arm 93 extends the return spring 95 in conjunction with the rotation of the clutch pedal 91. The rods 94 and 97 are slid in conjunction with each other through pin shafts 93a and 93b formed on the upper and lower ends of the arm 93, respectively, by rotating in the direction (leftward in FIG. 6).

  Then, the clutch switch 120 is pressed by the pressing tool 99 disposed on the upper surface of the contact portion 91d. As described above, when the rod 97 is slid rearward, the clutch 20 and the like are disengaged. In this case, the travel controller 110 determines that the clutch is “disengaged” via the clutch switch 120. On the other hand, when the operator releases the clutch pedal 91, the arm 93 is rotated rearward by the return spring 95 biased by the arm 93, and the rod 97 slides rearward in conjunction with the arm 93. Therefore, the clutch 20 and the like are returned to the engaged state. In this case, the travel controller 110 determines that the clutch is “engaged” via the clutch switch 120.

Next, the control means of the drive device according to this embodiment will be described in detail below.
As shown in FIG. 7, the travel controller 110 includes a main shift lever sensor 111 that is a means for detecting the rotation position of the main shift operation tool, and a direction changeover switch that is a means for detecting the rotation position of the forward / reverse switching operation tool. 102, a trunnion shaft angle sensor 64 for detecting the rotation angle of the trunnion shaft 61 as means for detecting the shift position of the transmission, an axle speed sensor 112 as means for detecting the rotational speed of the axle, and the rotational speed of the engine 2. An engine speed sensor 113 serving as a detecting means, pressure sensors 114 and 115 serving as means for detecting the pressure in the oil passages 81 and 82 of the HST 23, and a clutch switch 120 serving as a means for detecting connection / disconnection of the clutch are respectively connected.

  Solenoids 78b and 79a of electromagnetic valves 78 and 79 are connected to the traveling controller 110, and the electromagnetic valves 78 and 79 are switched by a control signal from the traveling controller 110 to drive the hydraulic cylinder 67 to expand and contract, thereby moving the movable swash plate. The angle of 53 can be changed. As described above, in the drive device according to the present embodiment, the travel controller 110 can control the HST 23 based on the detection value detected by the above-described main shift lever sensor 111 and the like. .

  The tractor 1 according to the present embodiment travels at a set speed that is determined by the operation of the sub-shift lever 10 that performs a gear shift operation in a normal state and the main shift lever 7 that determines the angle of the trunnion shaft 61 of the HST 23. However, there are cases where the operator performs a clutch operation without operating the main speed change lever 7 or the like during traveling of the vehicle, and thereafter stops the traveling of the work vehicle. When the clutch operation is released in such a case, the rotational speed of the main transmission lever 7 remains the same, so the set speed is high, and rapid start and rapid torque oscillation occur. Therefore, each time the clutch is operated, it is necessary to operate the main speed change lever 7 and the like so as to come to the neutral position.

  Therefore, in the driving apparatus according to the present embodiment, when the clutch operation is performed in order to eliminate such a problem, the movable swash plate 53 of the HST 23 is in a neutral stop state and the clutch is switched. Includes a control means for accelerating the HST 23 slower than usual and quickly bringing the tractor 1 to a predetermined vehicle speed when the tractor 1 becomes stable with acceleration.

Below, an example of the process which the tractor 1 which concerns on a present Example performs is explained in full detail.
As shown in FIG. 8, first, the current rotation position of the main transmission lever 7, the rotation position of the forward / reverse switching lever 8, the rotational position of the forward / reverse trunnion shaft 61, and the like are respectively detected by the sensors 111, 102,. 64 or the like (130). Next, whether or not the clutch is “disconnected” or “contacted” is determined by the clutch switch 120 that detects the depression of the clutch pedal 91 disposed in the clutch operation unit 89 (131).

  The operator connects and disconnects the clutch by depressing the clutch pedal 91 of the clutch operation unit 89 when the vehicle is stopped during the traveling operation. In this embodiment, the operator determines whether the clutch 20 is connected or disconnected. The control of the drive device is different. When the clutch pedal 91 is depressed and the clutch is disengaged, the clutch switch 120 is pressed and a signal from the clutch switch 120 is transmitted to the travel controller 110 to change the target position of the trunnion shaft 61 to neutral. Deviation calculation is performed (132).

  At the moment when the clutch operation is performed in a state where the hydraulic cylinder 67 is held at a certain traveling speed position, the power transmission from the engine 2 is cut off, and the speed quickly decreases from the set speed. When this clutch “disengaged” state occurs, the electromagnetic valves 78 and 79 are driven to quickly drive the hydraulic cylinder 67 so that the movable swash plate 53 becomes neutral. For this reason, every time the clutch is operated, the transmission can be prevented from being neutrally stopped without operating the main speed change lever 7 and the like, and can be prevented from proceeding in an unintended direction due to a control delay.

The forced neutral mechanism of the transmission according to the present embodiment is configured as follows.
As shown in FIG. 9, when each sensor switch is read (130), the rotation position of the main transmission lever 7 is read by the sensor 111, and the setting position of the main transmission lever 7 is in the neutral state (N-speed). If there is, the transmission is forcibly controlled by the travel controller 110 so that the target shift becomes neutral (134). If the set position of the main transmission lever 7 is other than the neutral state, the presence / absence of a signal from the direction switch 102 is determined (135). When the travel controller 110 detects a signal from the direction switch 102, that is, when the forward / reverse switching lever 8 is in a neutral state, the transmission controller 110 controls the transmission so that the target shift becomes neutral. It is forcibly controlled (134).

  When the signal of the direction switch 102 is not detected, that is, when the forward / reverse switching lever 8 is rotated to either the forward or reverse direction, the presence / absence of the signal of the clutch switch 120 is determined. A determination is made (136). When the travel controller 110 detects the signal of the clutch switch 120, that is, when the clutch is "disengaged", the travel device is forcibly controlled so that the target shift becomes neutral as described above (134). When the signal of the clutch switch 120 is not detected, that is, when the clutch is in the “engaged” state, the transmission is controlled so that the speed and direction set by the main transmission lever 7 are not controlled by the forced neutral mechanism. Is controlled.

  Thus, by providing the above-described forced neutral mechanism in the drive device according to the present embodiment, the safety of vehicle traveling is ensured, and inadvertent sudden start, complicated clutch operation, etc. are eliminated, and safety is ensured. And operability can be further improved. In addition, when the gear shift operation is performed, the transmission is brought into a neutral state at the timing of “disengagement” of the clutch, so that the vehicle can be safely stopped.

  Further, as shown in FIGS. 8 and 10, when the clutch pedal 91 is not depressed and no signal is generated in the clutch switch 120, whether or not the clutch pedal 91 is in the middle of returning from the depressed state. The control of the driving device is different (137). That is, when the signal of the clutch switch 120 is not detected, or when it is determined that the clutch “disengaged” is returned to the clutch “engaged”, the main transmission lever 7 detected by the main transmission lever sensor 111 is detected. The position of the trunnion shaft 61 corresponding to the rotational position is detected by the trunnion shaft angle sensor 64, and a deviation calculation from the current position to the set position is performed (138).

  If the clutch pedal 91 is in the clutch "disengaged" to "engaged" state and the trunnion shaft angle is in the process of returning, trunnion shaft angle deviation calculation and solenoid output width calculation are performed (139). When the clutch pedal 91 is released and the drive from the engine 2 is transmitted, if the speed is suddenly returned to the set speed of the main transmission lever 7, a rapid acceleration is given to the operator. This is a shock at the time of starting, which is not only uncomfortable for the operator, but may be a factor for reducing safety in some cases.

  Therefore, the trunnion shaft angle deviation calculation and the solenoid output width calculation (139) are performed so that the relationship between the trunnion shaft angle and time is as shown in FIG. That is, a map having a relationship as shown in FIG. 11 is stored in the memory of the controller 110 in advance, a control signal corresponding to the map is output, and the trunnion axis is changed gradually at first, Acceleration is gradually applied in the range where the running speed is from 0 (zero) to a low shock. Control is performed so that the trunnion shaft is quickly changed (turned) to the target position after the traveling speed of the vehicle is stabilized.

  In particular, the trunnion shaft angle deviation calculation and solenoid output width calculation are preferably performed as shown in FIG. That is, the relationship between the trunnion axis position and the trunnion axis angle change speed is also stored in the controller 110 as a map, and the change of the trunnion axis position is first driven gradually to give acceleration, and the trunnion axis angle change speed gradually increases. Then, before the target speed, that is, the trunnion shaft position decelerates the trunnion shaft angle change speed from the vicinity of the target position, and stops at the target position. According to such a control method, overshoot of the trunnion shaft position can be suppressed.

  By adopting such a configuration, after the clutch operation, the travel controller 110 controls the tilting of the movable swash plate 53 of the transmission, so that a special start operation or a special clutch operation such as a half clutch is not necessary. The work efficiency by the operator can be increased. Further, even when the traveling direction is changed after the vehicle main body is once stopped, a complicated clutch operation becomes unnecessary.

  Originally, the hydraulic cylinder 67 can be driven at every position of the trunnion shaft 61 or by determining the time from the start of driving and adjusting the driving speed by PWM control. However, in the driving apparatus according to the present embodiment, the vehicle acceleration changes even for the same shift operation depending on conditions such as HST efficiency, engine efficiency, work vehicle travel load, work load other than travel due to PTO, etc. Is not constant. Also, the degree of shock is not guaranteed for certain operations.

  Therefore, a change in the actual traveling speed is detected by the axle speed sensor 112, and the drive of the hydraulic cylinder 67 is adjusted so as to conform to a predetermined speed change pattern. That is, the difference between the vehicle acceleration and the vehicle acceleration intended by the trunnion axis change pattern is calculated from the detection value of the axle rotation speed sensor 112 (140). If the value of the obtained vehicle acceleration is larger than a certain value (141), the PWM output width is decreased according to the acceleration (142).

  With such a configuration, sudden torque vibration transmitted to the drive device when the clutch 20 or the like is connected is reduced. Further, when the clutch is engaged in the high speed range, the engine drive can be prevented from being suddenly transmitted to the axle and shocking the operator and the work vehicle body.

  The relationship between the main shift lever sensor value and the target shift is stored in advance in a memory as a map so as to have a relationship as shown in FIG. 13, and the deviation is calculated so as to change as described above. The deviation value is driven from the travel controller 110 to drive the solenoid to feed the hydraulic oil to the hydraulic cylinder 67, and the HST 23 is controlled (143).

  When the trunnion shaft 61 is rotated so that the speed set by the main speed change lever 7 is reached and the main speed change lever 7 is tilted in the forward direction, the reverse (deceleration) direction output parameter is calculated. Then, the contraction duty ratio is adjusted, the hydraulic cylinder 67 is operated to the contraction reverse side, and the trunnion shaft 61 is driven and output (144). Further, the trunnion shaft 61 drive output is stopped (145). Further, the forward side (increase) direction output parameter is calculated, the elongation duty ratio is adjusted, the hydraulic cylinder 67 is actuated to the reverse side, and the trunnion shaft 61 is driven and output (146).

  Then, the forward or reverse electromagnetic valves 78 and 79 are actuated to actuate the hydraulic cylinder 67, and it is determined whether or not the angle matches the angle set by the main transmission lever 7, and the hydraulic cylinder 67 is determined at the coincident position. Is stopped.

Next, the starter circuit of the engine 2 according to the present embodiment will be described below.
Conventionally, when the engine is started, the engine is not started unless the clutch pedal is depressed, that is, the rotational drive of the engine is not transmitted to the gear so that the operator does not start at an unintended timing. In general, a safety switch is connected in series with a starter switch to an engine starter circuit, and the engine can be driven when the safety switch is ON. Specifically, in a starter circuit provided with a starting motor, a starter switch and a safety switch are arranged and connected in series, and the safety switch is provided in a clutch operation unit.

  In the starter circuit according to the present embodiment, as shown in FIGS. 6 and 14, the clutch switch 120 serving as a means for detecting connection / disconnection of the clutch is also used as means for connecting / disconnecting the starter circuit. The large capacity relay 149 is arranged between the starter switch 147 and the starting motor 148, and the large capacity relay 149 is connected to the travel control controller 110 and the clutch switch 120. When the clutch pedal 91 is depressed and the clutch switch 120 is pressed and a signal is generated in the clutch switch 120, the large-capacity relay 149 is turned on at the same time, and the starter circuit is "connected".

  That is, the clutch switch 120 disposed in the clutch operation unit 89 is also used as the safety switch. With such a configuration, only one large-capacity relay 149 is added to the conventional starter circuit, and the large-capacity relay 149 serves as a safety circuit at the time of starting the engine 2 that has been conventionally used. Play the role of Therefore, it is not necessary to provide a plurality of expensive switches or the like in the clutch operation unit 89, and the structure necessary for mounting the switches can be kept simple. Moreover, it is possible to share parts between the drive device according to this embodiment and a vehicle that does not include a continuously variable transmission, which is economical.

  As described above, in addition to the case where the clutch switch 120 serves as both means for detecting connection / disconnection of the clutch and means for connecting / disconnecting the starter circuit, the clutch operation unit 89 is configured as shown in FIG. It is good. That is, the clutch operation unit 89 may be separately provided with a clutch switch 120 serving as a means for detecting connection / disconnection of the clutch and a safety switch 150 serving as a means for connecting / disconnecting the starter circuit. In the clutch operation part 89, the clutch switch 120 is placed on the pressing tools 99 and 100 disposed on the upper surface of the contact part 91d when the clutch pedal 91 is depressed and the contact part 91d is rotated. The safety switch 150 is pressed.

  In the starter circuit in this case, as shown in FIG. 16, the safety switch 150 is disposed between the starter switch 147 and the starting motor 148, and the clutch switch 120 is connected to the travel control controller 110. It is good also as a structure which does. By adopting such a configuration, the switches 120 and 150 are arranged on the same member, so that the maintainability is excellent.

The top view of the tractor which arrange | positioned the transmission which concerns on this invention. Side surface sectional drawing of a mission case. The skeleton figure which shows a drive transmission mechanism. The side view of the transmission part of a transmission case. Hydraulic circuit diagram. The side view of a clutch operation part. Control block diagram. FIG. FIG. FIG. The figure which shows the relationship between a trunnion shaft angle and time. The figure which shows the relationship between a trunnion shaft position and trunnion shaft angle change speed. The figure which shows the relationship between a main gear-shift lever sensor value and a target gear shift. Starter circuit diagram. The side view of the clutch operation part which concerns on another Example. The starter circuit diagram which concerns on another Example.

Explanation of symbols

1 Tractor 7 Main transmission lever 8 Forward / reverse switching lever 20 Clutch 23 HST
DESCRIPTION OF SYMBOLS 51 Hydraulic pump 52 Hydraulic motor 53 Movable swash plate 64 Trunnion shaft angle sensor 67 Hydraulic cylinder 89 Clutch operation part 91 Clutch pedal 102 Direction switch 110 Travel control controller 111 Main transmission lever sensor 120 Clutch switch

Claims (4)

  Means for detecting the rotation position of the main transmission operation tool, means for detecting the rotation position of the forward / reverse switching operation tool, means for detecting the transmission position of the transmission, and means for detecting connection / disconnection of the clutch, And a control means for controlling the transmission based on the detected value, wherein the control means places the transmission in a neutral stop state when the clutch is disengaged. A drive device for a working vehicle.   Means for detecting the rotation position of the main transmission lever, means for detecting the rotation position of the forward / reverse switching lever, means for detecting the transmission position of the transmission, means for detecting the engagement / disengagement of the clutch, and detection value And a control means for controlling the transmission based on the control means, the control means, when the clutch "disengaged" is changed to the clutch "engaged", the control means A work vehicle drive device characterized by gradually accelerating at an initial stage of speed and then increasing a speed of change.   The control means includes a means for detecting the vehicle speed, and the control means calculates the acceleration of the work vehicle from the change in the vehicle speed when the clutch is changed from “disengaged” to “engaged”, and shifts the acceleration so that the acceleration is below a certain level. The drive device for a work vehicle according to claim 1 or 2.   3. The work vehicle drive device according to claim 1 or 2, wherein the clutch operating portion includes means for detecting connection / disconnection of the clutch and means for connecting / disconnecting a starter circuit, and the clutch is disposed in the clutch operation portion. The drive device for a work vehicle, wherein the switch serves as means for detecting connection / disconnection of the clutch and means for connecting / disconnecting the starter circuit.

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