JP5555133B2 - Work vehicle - Google Patents

Description

  The present invention relates to a work vehicle that shifts a continuously variable transmission by a driving force of an actuator based on an operation of a shift pedal.

  As a work vehicle configured as described above, Patent Document 1 includes a shift pedal that can be operated forward and backward with reference to the neutral position, and a pedal sensor that detects an operation position of the shift pedal. The actuator for setting the angle of the swash plate of the hydrostatic continuously variable transmission is equipped with a pump cylinder, equipped with a swash plate sensor for detecting the angle of the swash plate, and an electromagnetic type that supplies hydraulic oil to the pump cylinder A configuration with a valve is shown.

  In this patent document 1, the control apparatus which controls a cylinder for pumps by controlling a valve based on the detection signal of a pedal sensor and the detection signal of a swash plate sensor is provided. This control device operates the pump cylinder by depressing the shift pedal to the forward side with reference to the neutral position (non-operating position) to increase the speed in the forward direction, and depressing the reverse side to the pump A control form is shown in which the cylinder is operated to increase the speed in the reverse direction.

JP 2008-39167 A

  As described in Patent Document 1, a pedal pedal depression operation is detected by a pedal sensor, a valve is controlled based on the detection result, hydraulic oil is supplied to a cylinder to drive an actuator, and this driving continuously In the operation sequence for shifting the transmission, the control delay tends to increase from the start of the operation of depressing the shift pedal to the start of the operation of the actuator, and the reaction from the operation of depressing the shift pedal to the shift is deteriorated.

  As one of the factors causing control delay, when operating the actuator in the stopped state, it is necessary to operate the spool of the valve from the neutral position to the position where the supply of hydraulic oil is started. May affect the control delay.

  Further, considering the control device system of Patent Document 1, the detection value of the pedal sensor is set as a target value, and control is performed based on the deviation between the target value and the feedback value of the tilt sensor. A dead zone is set based on the target value. In the case where the dead zone is set in this way, when the shift pedal is in the non-operating position, the feedback value of the tilt sensor exists in the dead zone region, so even when the shift pedal is depressed, Control was not performed until the feedback value reached the outside of the dead zone, which caused control delay.

  In particular, when there is a gap or rattling in the mechanical operating system that transmits the operation amount of the shift pedal to the sensor, there is room for improvement because it is easier to further increase the control delay described above.

  An object of the present invention is to rationally configure a work vehicle that operates a continuously variable transmission with a responsive response by the driving force of an actuator when a shift pedal is operated.

Feature of the present invention, the continuously variable transmission configured to accelerating the running speed by turnable operation from the neutral position of the shift operating member is provided, and based on the operation of the change pedal, the driving force of the actuator A work vehicle for rotating the continuously variable transmission by rotating the speed change operation member by :
A driven member that is supported by the speed change operation member so as to be integrally rotatable, and that is rotated by the actuator about a rotation axis of the speed change operation member;
The so via the driven member rotation driving force to the acceleration side in the speed-change operating member acts continuously, and control means for controlling said actuator,
It is provided in contact with the driven member, and rotates together with the shift pedal around the second rotation axis to allow rotation of the driven member by the actuator, and sets the operation limit position of the shift operation member. A swingable member that can be set,
The swinging member, when the shift pedal is in the non-operating position, as before Symbol shift operating member against the driving force of the actuator is held in the neutral position, the neutral reference position the driven member as a neutral holding portion for maintaining, the previous SL change pedal when it is depressed, to expand the amount of rotation of from the neutral reference position of the driven member larger the depression amount of the shift pedal, the driven A restricting portion that allows the member to rotate to a position corresponding to the operation limit position, and
When the driven member is located at the neutral reference position, the neutral holding portion is in a state orthogonal to the rotatable direction of the driven member and in a state orthogonal to a line toward the second rotation axis. It exists in the point comprised so that the said driven member may be contacted .

According to this configuration, the control means performs control to continuously apply the driving force of the actuator to the speed change operation member, and when the speed change pedal is in the non-operation position, the operation limit setting means determines the drive force of the actuator. The shift operation member is held in a neutral position against it. Further, when the shift pedal is depressed from the non-operation position, since the operation limit setting means, to enlarge the distance of the neutral position of the shift operating member operated to the limit position as a reference, shift by the driving force of the actuator The operating member is actuated to the actuation limit position, thereby realizing a shift of the continuously variable transmission. In other words, since the driving force from the actuator always acts on the speed change operation member, for example, the operation of depressing the speed change pedal without being affected by the time for operating the valve spool or the response delay of the control system. The gear shifting operation can be performed by the driving force from the actuator in a form linked to the.
Therefore, a work vehicle has been constructed that operates the continuously variable transmission with a responsive response by the driving force of the actuator when the shift pedal is operated.

The present invention, the continuously variable transmission is, the increasing forward speed by the operation of the forward side from the neutral position of the shift operating member Hayashi, to accelerating the reverse speed by the operation to the reverse side from the neutral position Composed of
The control means continuously applies a driving force to the forward or reverse side with respect to the speed change operation member based on one of a forward signal and a reverse signal output from the traveling direction setting means by human operation. To drive the actuator,
The follower member is configured to pre-advance side or the speed-change operating member is rotationally displaced to the reverse side so as to pivot actuation,
The restricting portion, and a forward-side regulating unit for setting the operation limit position to the forward side of the driven member, and a reverse-side regulating unit for setting the operation limit position to the reverse side of the driven member, is provided ,
The neutral holding part is constituted by a first part corresponding to the neutral reference position in the forward side restricting part and a second part corresponding to the neutral reference position in the reverse side restricting part,
The first part and the second part are configured to face each other in a parallel state,
In a state where the driven member is positioned at the neutral reference position, the driven member may be sandwiched between the first portion and the second portion .

  According to this, for example, when the vehicle body is moved forward, the traveling direction setting means sets the traveling direction of the vehicle body to the forward side, and the shift pedal is depressed forward to operate in conjunction with the depression of the shift pedal. The body is displaced. Since the driving force is continuously applied to the speed change operation member from the actuator to the forward side, the speed change operation member is a forward side restricting portion formed on the operating body with reference to the neutral position as the operating body is displaced. Operates to the regulated operating limit. Thus, the forward speed is increased by the continuously variable transmission in conjunction with the operation of the shift pedal. Further, when the vehicle body is moved backward, the vehicle body moving direction is set to the reverse side by the traveling direction setting means, and the shifting pedal is depressed forward, so that the operating body is displaced in conjunction with the depression of the shifting pedal. Similarly to the forward movement, the shift operation member is operated to the operating limit regulated by the reverse side regulating portion formed on the operating body with reference to the neutral position as the shift member is displaced. Thus, the reverse speed is increased by the continuously variable transmission in conjunction with the operation of the shift pedal. That is, by setting the traveling direction of the vehicle body in advance, it is possible to increase the traveling speed with good responsiveness by performing an operation of depressing the shift pedal forward regardless of whether the vehicle body is moved forward or backward.

  The present invention maintains a state in which the driving force is applied to the speed change operation member by escaping a part of the driving force applied to the speed change operation member from the actuator in a state where the speed change operation member is at the operation limit position. Maintenance means may be provided.

  According to this, the maintaining means keeps the drive force from the actuator continuously acting on the speed change operation member at the operation limit position by releasing a part of the drive force of the actuator, This eliminates the inconvenience that an excessive driving force acts on the operating system during the operation. By providing this maintaining means, the speed change operation of the continuously variable transmission which is responsive to the operation of depressing the speed change pedal is realized.

  In the present invention, the actuator is constituted by a double-acting hydraulic cylinder, the control means for controlling the hydraulic oil supplied to the hydraulic cylinder by the maintaining means, and the pressure of the oil passage for supplying the hydraulic oil to the hydraulic cylinder. You may comprise with the relief valve which escapes.

According to this, when the speed change operation member is in the neutral position or in the operation limit position, the relief valve releases the pressure of the hydraulic oil, and the structure is simply provided with a relief valve having a relatively simple structure. This eliminates the inconvenience of applying an excessive force between the hydraulic cylinder and the speed change operation member without causing complication.

The present invention includes an engine that supplies driving force to the continuously variable transmission, and when the shift pedal is in a non-operation position, the rotational speed of the engine is reduced, and the shift pedal is operated from the non-operation position. A speed control means for increasing the rotational speed of the engine when
The speed control means may include an operation amount expansion mechanism that expands an operation amount of the shift pedal and transmits it to the speed control mechanism of the engine when the shift pedal is depressed from the non-operation position.

According to this, when the speed change pedal is in the non-operation position, the speed control means decreases the rotational speed of the engine, and when the speed change pedal is depressed, the speed control means increases the speed of the engine. Further, the speed control means expands the operation amount of the shift pedal by the operation amount expansion mechanism and transmits it to the engine speed control mechanism, so that the engine speed is set low when the shift pedal is in the non-operation position. The engine operating noise and engine vibration do not make the driver uncomfortable. When the shift pedal is depressed, the engine rotational speed is greatly increased, thereby avoiding the inconvenience of engine stoppage.

It is a general view which shows a tractor. It is a top view which shows the rear part of a tractor. It is a side view which shows the relationship between the trunnion shaft in a neutral position, and a rocking | fluctuation plate. It is a side view which shows the relationship between the trunnion shaft in the advance area | region, and a rocking | fluctuation plate. It is a side view which shows the relationship between the trunnion axis | shaft in a reverse drive area | region, and a rocking | swiveling plate. It is sectional drawing which shows the site | part of a trunnion axis | shaft, etc. It is a block diagram which shows a control structure. It is a side view which shows the positional relationship of a guide hole and a to-be-driven part in the state which has a speed change pedal in a non-operation position. It is a side view which shows the positional relationship of a guide hole and a to-be-driven part in the state in which the shift pedal was depressed. It is a side view which shows the structure of a cruise control mechanism. It is a top view which shows the operation system of a cruise control mechanism.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment / Overall Configuration]
As shown in FIGS. 1 and 2, an engine 4 is provided at a front position of a vehicle body 3 provided with left and right front wheels 1 and left and right rear wheels 2. A transmission system for transmitting to the front wheel 1 and the rear wheel 2 is provided, and a tractor as a work vehicle is configured with a driving unit at a central position of the vehicle body 3.

  The tractor includes a clutch housing 5 for intermittently driving the engine 4, a center frame 6 disposed at a center position of the vehicle body 3, a hydrostatic continuously variable transmission 7 for continuously changing power, A transmission case 8 incorporating a sub-transmission mechanism (not shown) and the like are arranged in this order from the front position of the vehicle body 3 to the rear part. In addition, the driving unit includes a step 11 on which the driver gets on and a driving seat 12 on which the driver is seated, and the steering operation is performed on the left and right front wheels 1 arranged at the front position of the driving seat 12. A steering wheel 13, a forward / reverse selection lever 14, a main clutch pedal 15, a single speed change pedal 16, and a pair of brake pedals 17.

  The clutch housing 5 has a built-in clutch mechanism (not shown) that cuts off the power when the main clutch pedal 15 is depressed. The continuously variable transmission 7 has a function of shifting the driving force from the engine 4 steplessly and transmitting it to the transmission case 8, and the driving force transmitted to the transmission case 8 by an operation of depressing the shift pedal 16 forward. Increase speed. The transmission case 8 further shifts the driving force from the continuously variable transmission 7 by a gear-type auxiliary transmission (not shown). The transmission case 8 has a built-in differential mechanism (not shown) that transmits driving force to the left and right rear wheels 2, and an output system that transmits the driving force from the transmission case 8 to the left and right front wheels 1. Is formed.

  At the rear of the mission case 8, a pair of left and right lift arms 9 that swing up and down by the operation of a hydraulic cylinder (not shown) provided in the mission case 8, and a power take-out shaft that enables the drive force to be taken out to the outside 10 are provided. This makes it possible to connect a working device such as a rotary tiller or a plow so that it can be moved up and down by the left and right lift arms 9, and from the power take-out shaft 10 to a drive-type working device such as a rotary tiller. It is possible to convey the driving force of

  As shown in FIGS. 3 to 7, the continuously variable transmission 7 includes an axial plunger type hydraulic pump P configured as a variable displacement type, and hydraulic oil from the hydraulic pump P via a pair of main oil passages 21. An axial plunger type hydraulic motor M that rotates at a speed corresponding to the amount of oil by being supplied and discharged is provided. The hydraulic pump P is driven by the engine 4 and adjusts the amount of hydraulic oil supplied to the hydraulic motor M by changing the angle (swash plate angle) of a pump swash plate (not shown). The driving speed of the hydraulic motor M can be changed. The continuously variable transmission 7 is provided with a hydraulic oil replenishment system that supplies hydraulic oil from the charge pump CP driven by the engine 4 to the main oil path 21 via the replenishment oil path 22.

A trunnion shaft 25 as a speed change operation member for changing the swash plate angle protrudes from the side surface of the continuously variable transmission 7, and the trunnion shaft 25 is a transmission shaft core as a “rotating shaft core” in a lateral orientation. The swash plate angle is changed by rotating about X.

  The trunnion shaft 25 is set to a neutral position N (a preset rotation angle position for neutral), so that the supply of hydraulic fluid from the hydraulic pump P to the hydraulic motor M is stopped and the continuously variable transmission 7 sends a mission. Stop transmission to case 8. In addition, when the trunnion shaft 25 is rotated from the neutral position N to the forward region F (forward side), the driving oil is supplied to the hydraulic motor M in the forward direction so that the vehicle body 3 moves forward. Tell case 8. When the vehicle is rotated from the neutral position N to the reverse region R (reverse side), hydraulic oil is supplied in a direction to reverse the hydraulic motor M to transmit the driving force for moving the vehicle body 3 backward to the transmission case 8.

  Since the hydraulic pump P is configured as a variable displacement type, the amount of hydraulic oil supplied to the hydraulic motor M is increased as the trunnion shaft 25 is greatly rotated in the forward region F to increase the forward speed of the vehicle body 3. On the contrary, as the trunnion shaft 25 is rotated more greatly in the reverse region R, the amount of hydraulic oil supplied to the hydraulic motor M increases and the reverse speed of the vehicle body 3 increases.

[Speed change operation structure]
A shift control body 26 that operates integrally with the trunnion shaft 25 is connected to the trunnion shaft 25 so as to extend upward from the trunnion shaft 25. The shift control body 26 is integrally formed with a driven arm 26D and a driven arm 26F. A driven portion 26Da on which a roller is rotatably fitted is provided at the tip of the driven arm 26D, and the driven arm 26F is provided. At the front end of this is provided a driven portion 26Fa as a “driven member” in which a roller is rotatably fitted as a contact portion.

  A transmission cylinder 27 (an example of an actuator) that is a double-acting hydraulic cylinder is disposed on the side surface of the continuously variable transmission 7 with the longitudinal direction of the vehicle body 3 set as the operation direction. The cylinder portion 27A of the speed change cylinder 27 is connected to an operation plate 28 in a posture of hanging downward, and a driven portion 26Da is fitted into the long hole 28A of the operation plate 28. The transmission cylinder 27 and the transmission control body 26 are compactly arranged along the side surface of the center frame 6 at a location above the trunnion shaft 25 so as to be T-shaped in a side view.

  The transmission cylinder 27 has an oil chamber formed at a position sandwiching the piston 27B by disposing the piston 27B in the center position in the operation direction inside the cylinder portion 27A, and piston rods 27C connected to the piston 27B are connected to both ends of the cylinder portion. It has a structure protruding from. An end of the piston rod 27C is connected to the vehicle body side (the transmission case 8 and the continuously variable transmission 7) by a bolt 29, and a hydraulic oil passage 30 is provided for supplying and discharging hydraulic oil to and from the two oil chambers. It has been.

  With such a configuration, the hydraulic oil is supplied to one of the pair of hydraulic oil passages 30 and the oil is discharged from the other hydraulic oil passage 30 to drive the cylinder portion 27A. As a result of the movement of the drive unit 26Da, the trunnion shaft 25 rotates about the speed change shaft core X, and the speed change operation of the continuously variable transmission 7 is realized. This oil passage system will be described in a shift control configuration described later.

In this tractor, a shift pedal shaft 34 is provided on the side surface of the center frame 6 on the same axis as the operation shaft Y as a “second rotation shaft core” in a lateral orientation , with respect to the shift pedal shaft 34. A cylindrical portion 16B at the base end of the pedal arm 16A of the speed change pedal 16 is rotatably fitted and supported. As a result, the transmission pedal 16 is supported so as to be operable about the operation axis Y. The cylindrical portion 16 </ b> B is provided with an operating lever 35, and one end of the return spring 36 and one end of the damper 37 are connected to the operating lever 35. The return spring 36 and the damper 37 are disposed below the speed change cylinder 27 in the upper part of the speed change pedal shaft 34, and are arranged in a straight line in the front-rear direction in a side view.

  The shift pedal 16 is lifted upward by the urging force of the return spring 36 in the non-operating state, and the lifting limit is determined by the operation limit of the damper 37 and is held at the non-operating position shown in FIG. A stopper 40 is provided on the side surface of the center frame 6 to determine the limit on the depression side of the speed change pedal 16. Further, when the driver lifts his / her foot from the shift pedal 16 with the shift pedal 16 being depressed deeply, the damper 37 suppresses a rapid return to the non-operation position.

The cylindrical portion 16B rotates about the operating axis Y as the shift pedal 16 is depressed, and the cylindrical portion 16B is provided with a fan-shaped swing plate 38 as a “swing member” . A guide hole 39 as a “regulator” is formed in the swing plate 38, and a driven portion 26 Fa formed in the speed change control body 26 is inserted into the guide hole 39. The guide hole 39 is formed in a shape that enlarges the rotatable region of the transmission control body 26 around the transmission shaft core X as the oscillation amount of the oscillation plate 38 increases.

Considering an arc-shaped reference line D centered on the operation axis Y, the guide hole 39 is formed in a long hole shape along the reference line D, and the guide hole 39 is a forward movement of the speed change control body 26. A forward side restricting portion 39F that determines the operation limit position to the side, and a reverse side restricting portion 39R that determines the operation limit position on the reverse side. Thus, in detail, the “restricting portion” of the present invention is configured by the forward-side regulating portion 39F and the reverse-side regulating portion 39R. Further, when the shift pedal 16 is depressed forward, the reference line D is set so that the region in which the shift control body 26 can be rotated forward and backward is increased as the depression amount is increased. It is shape | molded in the shape which expands the distance to 39 A of forward side control parts and the reverse side control part 39R.

  As described above, the operation limit setting means is configured by the guide hole 39 that increases the distance to the operation limit position based on the neutral position N of the trunnion shaft 25 as the operation amount of the shift pedal 16 is increased. Further, since the guide hole 39 includes a forward side restricting part 39F and a reverse side restricting part 39R, and these are configured to determine the operating limit of the driven part 26Fa, the operating limit setting means includes the forward side restricting part 39F and the reverse side restricting part. The side regulating portion 39R and the driven portion 26Fa are included.

Since the operation limit setting means is configured in this way, as shown in FIG. 8, when the shift pedal 16 is in the non-operation position, the shift pedal 16 is maintained at the highest position by the urging force of the return spring 36. At the same time, the swing end (left end portion in FIG. 8) of the swing plate 38 is maintained at the lowest position. In this state, the driven portion 26Fa of the driven arm 26F reaches the upper end position of the guide hole 39 and is sandwiched between the forward side restricting portion 39F and the reverse side restricting portion 39R, so the trunnion shaft 25 connected to the speed change control body 26 is in the neutral position. N is held, and the vehicle body 3 is stopped.

When the swing plate 38 is in the posture shown in FIG. 8, the driven portion 26 </ b> Fa is at the neutral reference position Pn corresponding to the neutral position N of the trunnion shaft 25. Here, assuming a limit line E connecting the the neutral reference position Pn and the operation axis Y linearly (line directed to the second rotation axis corresponds to), the upper limit line E of the forward-side regulating portion 39F The first portion 39Fa that intersects the upper limit line E and the second portion 39Ra that intersects the upper limit line E in the reverse side restricting portion 39R are substantially perpendicular to the upper limit line E. Thereby, for example, even when an external force that rotates about the transmission shaft core X due to vibration from the vehicle body 3 acts on the transmission control body 26, the external force is applied to the forward side regulating portion 39F or the reverse side regulating portion 39R. Therefore, the trunnion shaft 25 can be stably held at the neutral position N without generating a component force for rotating the rocking plate 38. The first portion 39Fa and the second portion 39Ra correspond to the “neutral holding portion” of the present invention.

Further, when the shift pedal 16 is depressed, as shown in FIG. 9, the swinging end of the swinging plate 38 (the left end in FIG. 9) is displaced in the lifting direction, and both sides of the driven portion 26Da. A gap is formed in the portion (part along the front-rear direction of the vehicle body 3), and the trunnion shaft 25 can be displaced from the neutral position N to the forward region F and the reverse region R. As shown in the figure, when the swing plate 38 is swung to the intermediate position by operating the speed change pedal 16, the neutral reference position Pn of the driven portion 26Fa corresponding to the neutral position N of the trunnion shaft 25 is used as a reference. This follower 26Fa can move to the forward reference position Pf or the reverse reference position Pr .

The work dynamic limit setting means, the forward side stroke Fs to the forward reference position Pf on the basis of the neutral reference position Pn, so as to increase from the reverse side stroke Rs to reverse reference position Pr relative to the neutral reference position Pn The shapes of the forward side restricting part 39F and the reverse side restricting part 39R are set. Therefore, even when the shift pedal 16 is depressed by the same amount, the forward speed is higher than the reverse speed.

  When the driver depresses the shift pedal 16 forward to drive the vehicle body 3 and then lifts his / her foot from the shift pedal 16, the oscillating plate 38 is moved to FIG. The trunnion shaft 25 returns to the neutral position N and the vehicle body 3 stops.

[Automatic speed control unit]
In this tractor, when the vehicle body 3 is caused to travel, the engine 4 is stopped by performing a shift with the continuously variable transmission 7 in a state where the rotational speed of the engine 4 is increased (basically an upper limit). This achieves a gearless transmission. For this reason, conventionally, the engine 4 has been kept at a high rotational speed during work. However, the operating sound of the engine 4 is large and fuel is easily consumed. 4 is provided with an automatic governing unit that increases the rotational speed.

  As shown in FIG. 3, both ends of the support plate 45 close to the outer surface of the operation plate 28 are supported by the center frame 6, and a pickup arm 47 (operating with respect to the support plate 45 via a pivot pin 46 is swingable. An example of a quantity expansion mechanism is supported, and a detection pin 48 projecting from the swing plate 38 is inserted into a long hole portion 47A formed at the detection end of the pickup arm 47, and is connected to the output end of the pickup arm 47. The connected operation wire 49 is connected to the speed governing mechanism 4A of the engine 4 to constitute an automatic speed governing unit.

  The speed control mechanism 4A is linked to an operation arm that adjusts the amount of fuel supplied by the throttle valve, and increases the rotational speed of the engine 4 by increasing the pulling operation amount from the operation wire 49. It is linked so as to reduce the rotational speed of the engine 4 by reducing the operation amount. Thus, the speed control means is constituted by the operation system from the pickup arm 47 to the speed control mechanism 4A. The speed adjusting mechanism 4A may be linked to a control system that adjusts the amount of fuel supplied to the injection nozzle.

  The pickup arm 47 swings the swing plate 38 by setting the distance from the pivot pin 46 to the connecting portion of the operation wire 49 larger than the distance from the pivot pin 46 to the long hole portion 47A. The operation amount is enlarged and transmitted to the speed governing mechanism 4A. With such a configuration, when the speed change pedal 16 is in the non-operation position, the rotational speed of the engine 4 is reduced, and when the speed change pedal 16 is depressed, the speed of the engine 4 is greatly increased. .

[Shift control configuration]
As shown in FIG. 7, a detection signal from a forward / reverse selector switch 70 (an example of a traveling direction setting means) operated by the forward / reverse selection lever 14 is input, and the solenoid valve is configured to control the transmission cylinder 27. A control device 71 (an example of a control means) that outputs a control signal to the control valve 71 and the forward / reverse notification unit 72 constitutes a shift control system. In order to supply hydraulic oil to the control valve 71, a hydraulic pump 75 driven by the engine 4 is provided, and a flow rate control valve 77 and a relief valve 78 are connected to an oil passage 76 for supplying the hydraulic oil from the hydraulic pump 75 to the control valve 71. (An example of maintenance means).

  The forward / reverse selection lever 14 is configured as a toggle type that maintains the operation state of either the forward side or the reverse side, and the forward / reverse selector switch 70 continuously outputs one of the forward signal and the reverse signal. It is configured as a toggle type. The forward / reverse notification unit 72 includes a lamp display unit 72A having two lamps that indicate the traveling direction of the vehicle body 3, and a speaker 72B that outputs a back alarm by voice during reverse travel. The control device 73 acquires a signal from the forward / reverse selector switch 70 and lights one of the forward or reverse lamps of the lamp display unit 72A, and outputs a back alarm from the speaker 72B in reverse.

  The forward / reverse selector switch 70 may be a different type of operating tool such as a momentary type that is held in a neutral position when not operated or a push button type. The device 73 performs processing for storing the forward signal and the reverse signal. Further, the forward / reverse notification unit 72 may display a traveling direction of the vehicle body 3 with characters and icons like an LCD, for example.

  The control device 73 includes a processing system such as a CPU or a DSP, thereby realizing necessary processing based on the detection signal. As a control mode, when a forward signal is acquired from the forward / reverse selector switch 70, the control valve is configured so that the driving force from the speed change cylinder 27 continuously (always) acts on the trunnion shaft 25 toward the forward region F. The control signal for controlling 71 is continuously output, and the forward-side lamp of the lamp display unit 72A is turned on. Further, when a reverse output signal is acquired from the forward / reverse selector switch 70, the driving force from the speed change cylinder 27 is controlled so as to continuously (always) act on the trunnion shaft 25 toward the reverse region R. A control signal for controlling the valve 71 is continuously output, the reverse lamp of the lamp display unit 72A is turned on, and a back alarm is output from the speaker 72B.

[Second Embodiment / Cruise Control Mechanism]
In the second embodiment, a cruise control mechanism additionally provided in the configuration of the tractor described in the first embodiment will be described. In the second embodiment, the configuration of the tractor, the speed change mode of the continuously variable transmission 7 and the like are not described, but the description will be given on the assumption that the configuration provided in the first embodiment is provided.

  As shown in FIG. 10, a sawtooth portion 38 </ b> S is formed in the swing end region of the swing plate 38, and the lock member 51 that engages and disengages with the sawtooth portion 38 </ b> S has a shaft body 52 on the side surface of the continuously variable transmission 7. It is supported so that it can swing freely. An operation system linked to the cruise lever 18 is provided so as to set the lock member 51 to either one of the locked posture and the unlocked posture. The serrated portion 38S, the lock member 51, and the cruise lever 18 A cruise control mechanism is configured with a linked operation system.

  The lock member 51 includes an engagement arm portion 51A having a serrated engagement surface 51S, a lock operation arm portion 51B that receives an operation force for operating the lock member 51 to a locked posture, and an unlocking posture for the lock member 51. An unlocking arm portion 51 </ b> C that receives an operating force to be operated is integrally formed.

  A support pin 53 is provided in the vicinity of the lock member 51 on the side surface of the continuously variable transmission 7, and a toggle spring 54 formed of a compression coil spring is provided between the support pin 53 and the lock operation arm portion 51B. The toggle spring 54 has a function of applying an urging force for holding the lock member 51 in either the lock posture or the release posture. That is, in FIG. 10, when the biasing force action point at which the toggle spring 54 contacts the lock operation arm 51B is above the neutral straight line T connecting the support pin 53 and the shaft body 52, the biasing force of the toggle spring 54 The lock member 51 is maintained in the locked posture, and the state in which the engagement surface 51S is engaged with the sawtooth portion 38S is maintained. When the urging force application point is below the neutral straight line T, the lock member 51 is maintained in the unlocked posture by the urging force of the toggle spring 54, and the engagement surface 51S is separated from the sawtooth portion 38S. Maintained.

  One end of a lock operation wire 55 is connected to the lock operation arm 51B via a connection pin 55A, and the other end of the lock operation wire 55 is connected to the cruise lever 18 via a connection pin 55B.

  A laterally-positioned brake pedal shaft 58 is provided on the side surface of the center frame 6, and the cylindrical body 17 </ b> B at the base end of each pedal arm 17 </ b> A of the pair of left and right brake pedals 17 can swing with respect to the brake pedal shaft 58. The outer fitting is supported. The left and right cylindrical bodies 17B are provided with an operation lever 59, and a lock release link L is provided between the left and right operation levers 59 and the lock release arm portion 51C.

  Although not shown in the drawings, the left cylindrical body 17B is linked to a brake device (not shown) of the left rear wheel 2 via a rod, a wire, or the like, and the right cylindrical body 17B is a rod or wire. It is linked to a brake device (not shown) for the right rear wheel 2 via a wire or the like, and a biasing force of a return spring is acting on the left and right brake pedals 17. Thereby, in the non-operating state, the left and right brake pedals 17 are held at the non-operating position, and the left and right brake pedals 17 are separately depressed to realize independent braking of the left and right brake devices. When the vehicle body 3 is turned, the driver controls the rear wheel 2 inside the turn by turning the steering wheel 13 and simultaneously depressing the left and right brake pedals 17 corresponding to the inside of the turn. The turning of the vehicle body 3 is realized with a small turning radius by applying power.

  As shown in FIGS. 10 and 11, the lock release link L includes a main link member 61 that is connected to the lock release arm portion 51 </ b> C via a first connection pin 61 </ b> A, and an intermediate pin 63 that is connected to the main link member 61. One end is connected via a second connecting pin 65A to the link body 64 connected via the link body 64 and the left and right link plates 64B formed on the link body 64, and the left and right operation levers are connected via the third connecting pin 65B. And left and right intermediate plates 65 connected to 59. Further, left and right operation levers 59 having different lengths are used.

  The main link member 61 and the unlocking arm portion 51C are connected so as to be swingable around the first connecting pin 61A, and the main link member 61 and the link body 64 are freely swingable around the intermediate pin 63. The left and right link plates 64B and the intermediate plate 65 are swingably connected around the second connection pin 65A, and the left and right intermediate plates 65 and the left and right operation levers 59 are centered on the third connection pin 65B. In this way, it is swingably connected. A long hole 64A is formed in the link body 64 so that when a pulling operation force is applied to the unlocking link L, the left and right link bodies 64 can be independently displaced in the longitudinal direction of the long hole 64A.

  With this configuration, the driver operates the shift pedal 16 forward while the lock member 51 is in the unlocked posture, and the cruise lever 18 is operated in the direction indicated by the arrow in FIG. As a result of the member 51 reaching the locking posture, the engaging surface 51S of the locking member 51 is engaged with the serrated portion 38S of the swing plate 38, and this locking posture is maintained by the urging force of the toggle spring 54. A cruise state is reached that maintains the state mechanically.

  The unlocking link L does not unlock when only one of the left and right brake pedals 17 is depressed, and only when the left and right brake pedals 17 are depressed simultaneously, the lock member 51 is unlocked. It functions to switch to. In order to realize such an operation, the third connection pin 65B is disposed at an intermediate position between the third connection pins 65B of the left and right operation levers 59 in the side view shown in FIG. Two intermediate plates 65 are arranged in a Y-shaped branch shape as a reference.

  A direction from the unlocking arm portion 51C of the lock member 51 toward the front of the vehicle body 3 is defined as a “straight operation direction”, and an operation amount necessary for switching the lock member 51 to the unlocking posture is defined as a “necessary stroke”. When the left and right brake pedals 17 are simultaneously depressed, the lock release link L applies an operation force along the “linear operation direction” from the left and right operation levers 59 to the lock release arm portion 51C to lock the lock release link L. The release arm 51C is configured to be operated by an amount slightly exceeding the “necessary stroke”.

  Further, when only one of the left and right brake pedals 17 is depressed, the unlocking link L acts on the unlocking arm portion 51C of the lock member 51 from the operation lever 59 of the brake pedal 17 that has been depressed. The acting force acts in an oblique direction deviating upward or downward from the “linear operation direction”, and the stroke acting on the unlocking arm 51C does not reach the “required stroke”.

  In particular, when the left and right brake pedals 17 are depressed simultaneously in the cruise state (the lock member 51 is in the locked position), the lock member 51 is unlocked before the braking force is applied to the left and right brake devices. The operation timing is set to switch to. When the cruise state is released, the shift pedal 16 is displaced in the direction of the non-operation position, so that it can be determined that the cruise state has been released.

[Control form including the first embodiment and the second embodiment]
With such a configuration, when the speed change pedal 16 is in a non-operating state as shown in FIG. 3, the position of the guide hole 39 of the swing plate 38 sandwiched between the forward side restricting portion 39F and the reverse side restricting portion 39R. Since the driven portion 26Fa is provided, the trunnion shaft 25 is not rotated and held at the neutral position N against the driving force of the transmission cylinder 27. As a result, the driving force is not transmitted from the continuously variable transmission 7 to the front wheels 1 and the rear wheels 2, and the vehicle body 3 does not travel. Thus, since the traveling direction is set by the forward / reverse selection lever 14 even when the shift pedal 16 is in the non-operating position, the hydraulic oil is discharged from the relief valve 78 and the trunnion from the shift cylinder 27. A rotational force is continuously (always) applied to the shaft 25.

  Further, when the vehicle body 3 is moved forward, the driver sets the traveling pedal 16 from the non-operating position with the traveling direction set to forward by operating the forward / reverse selection lever 14 as shown in FIG. By performing the stepping operation forward, the rear end side of the swing plate 38 swings upward together with the stepping operation forward, and the forward side regulation based on the reference line D (see FIGS. 8 and 9). The distance to the portion 39F is enlarged, and the displacement of the driven portion 26Fa in the forward region F is allowed by this enlarged amount. As described above, since the rotational operation force is continuously (always) acting on the trunnion shaft 25 from the transmission cylinder 27, the forward movement is made by the driving force from the transmission cylinder 27 in conjunction with the depression of the transmission pedal 16. The vehicle body 3 is moved forward by rotating in the direction of the region F and applying a driving force to the front wheel 1 and the rear wheel 2 from the continuously variable transmission 7.

  When the vehicle body 3 is moved backward, the driver performs an operation of setting the traveling direction to reverse by operating the forward / reverse selection lever 14, and depresses the shift pedal 16 forward as shown in FIG. As a result, the rear end side of the swing plate 38 swings upward along with the stepping operation forward, and the distance to the reverse side restricting portion 39R based on the reference line D (see FIGS. 8 and 9) is increased. Then, the displacement of the driven portion 26Fa in the reverse region R is allowed by this enlargement. As described above, since the rotational operation force is continuously (always) applied from the speed change cylinder 27 to the trunnion shaft 25, the drive force from the speed change cylinder 27 reverses with the depression of the speed change pedal 16. The vehicle body 3 is rotated in the direction of the region R, and the vehicle body 3 is moved backward by applying a driving force to the front wheels 1 and the rear wheels 2 from the continuously variable transmission 7.

  That is, in this work vehicle, a driving force is applied from the transmission cylinder 27 so that the trunnion shaft 25 of the continuously variable transmission 7 is rotated to the forward region F or the reverse region R, and the driver moves the shift pedal 16 forward. When the stepping operation is performed, the driving force from the speed change cylinder 27 is applied to the trunnion shaft 25 of the continuously variable transmission 7 to realize speed change. Therefore, for example, a shift with good responsiveness by the driving force of the shift cylinder 27 is realized in a form interlocked with the depressing operation of the shift pedal 16 without being affected by the time to operate the valve spool and the response delay of the control system. doing.

  In particular, when the speed change pedal 16 is in the non-operating position, the pickup arm 47 is in the posture shown in FIG. 3, so that the rotational speed of the engine 4 is low, and the operating sound and engine vibration of the engine 4 are There is no discomfort. When the shift pedal 16 is depressed, the speed adjusting mechanism 4A is operated by pulling the operation wire 49 while the swinging amount of the swinging plate 38 is enlarged by the pickup arm 47, as shown in FIG. Is operated to increase the rotational speed of the engine 4 to a required level, and traveling in a state where engine stop is avoided is realized.

  Further, when the driver performs work while traveling at an arbitrarily set speed, the cruise lever 18 is moved to the speed required by the driver by depressing the speed change pedal 16, and the cruise lever 18 is moved to the arrow shown in FIG. , The locking member 51 reaches the locking posture as shown by the phantom line, the engaging surface 51S of the locking member 51 is engaged with the sawtooth portion 38S of the swing plate 38, and the toggle spring 54 is attached. This engagement state is maintained by the force. As a result, the rocking plate 38 is rocked in accordance with the amount of depression of the speed change pedal 16, and the engagement surface 51S of the lock member 51 is engaged with the sawtooth portion 38S of the rocking plate 38. As a result, the position of the driven portion 26Fa by the operation limit setting means is maintained, and the cruise state appears.

  In such a cruise state, when the driver depresses both the left and right brake pedals 17 at the same time, the depressing operation force causes the pulling operation force to act on the unlocking arm portion 51C of the lock member 51 from the unlocking link L. As the lock member 51 reaches the unlocking posture, the connecting pin 55A reaches a position below the neutral straight line T, and this releasing posture is maintained by the biasing force of the toggle spring 54. As a result, the cruise state is canceled, and a shift operation based on the operation of the shift pedal 16 by the driver becomes possible. In particular, when the left and right brake pedals 17 are simultaneously depressed in the cruise state, the cruise state can be canceled in a state where the braking force is not applied to the left and right brake devices, so that the traveling speed is not reduced.

[Another embodiment]
The present invention may be configured as follows in addition to the embodiment described above.

(A) As a continuously variable transmission 7 that performs only forward or reverse travel, a speed change operation member that winds an endless belt around two pulleys whose winding diameter can be changed and changes the winding diameter of the pulley is provided. Alternatively, a belt-type CVT may be used, or a CVT having a tapered cone and a disk that contacts the outer surface of the tapered cone and a shift operation member that changes the respective contact position may be used. When the continuously variable transmission 7 is provided on the vehicle body, the vehicle body can be moved forward and backward by combining it with a gear transmission mechanism that performs forward / reverse switching.

(B) An electric motor may be used as the actuator. When the electric motor is used in this way, as a means for maintaining the state in which the driving force is applied to the swing plate ( swing member ), the friction that causes slipping when the driving force having a torque exceeding the set value is applied. A clutch may be provided. When the friction clutch is provided as described above, the degree of slipping of the friction clutch is set so that the return is permitted by slipping of the friction clutch when the shift pedal is returned to the non-operating state by the return spring.

(C) As an operation limit setting means, for example, a cam plate having a cam hole is provided so as to swing integrally with the trunnion shaft 25, and a cam follower such as a roller disposed inside the cam hole of the cam plate is provided. You may comprise in the arm etc. which rock | fluctuate integrally with the speed change pedal 16, etc. When the operation limit setting means is configured in this way, the trunnion shaft 25 is maintained at the neutral position N in a situation where the shift pedal 16 is in the non-operating position, and the trunnion shaft 25 increases as the shift pedal 16 is depressed. The shape of the cam hole is set so as to rotate greatly.

  In this other embodiment (c), the shape of the cam hole can be assumed to approximate an inverted triangle. In this cam hole, two sides sandwiching the lower apex are formed as a forward side restricting portion and a reverse side restricting portion. When the speed change pedal 16 is in the non-operation position, the cam follower is located at the lower end (vertex) of the cam hole. Therefore, the trunnion shaft 25 can be held at the neutral position N by restraining the cam plate. When the shift pedal 16 is depressed, the cam follower rises to an intermediate position of the cam hole, and a space is formed between the cam follower, the forward side restricting portion, and the reverse side restricting portion. Thus, the continuously variable transmission is realized in such a manner that the trunnion shaft 25 is rotated to a position where the cam follower comes into contact with the forward side restricting portion or the reverse side restricting portion.

  The present invention can be used for all work vehicles including a continuously variable transmission.

4 engine 4A speed control mechanism 7 continuously variable transmission 16 shift pedal 25 shift operating member (trunnion shaft)
26Fa driven member (driven part)
27 Actuator / Hydraulic Cylinder (Transmission Cylinder)
38 Oscillating member (oscillating plate)
39F Restriction Department / Advance Restriction Department
39Fa First part 39R Restriction part / reverse drive restriction part
39Ra Second part 47 Operating amount expansion mechanism (pickup arm)
70 Travel direction setting means (forward / reverse selector switch)
71 Control valve 73 Control means (control device)
78 Maintenance means (relief valve)
E Line toward the second pivot axis (upper limit line)
N Neutral position
Pn neutral reference position
X Rotating shaft core (shifting shaft core)
Y Second pivot axis (operation axis)

Claims (5)

Continuously variable transmission configured to accelerating the running speed by turnable operation from the neutral position of the shift operating member is provided, and based on the operation of the change pedal, the shift operating member by the driving force of the actuator A work vehicle that rotates and continuously operates the continuously variable transmission,
A driven member that is supported by the speed change operation member so as to be integrally rotatable, and that is rotated by the actuator about a rotation axis of the speed change operation member;
The so via the driven member rotation driving force to the acceleration side in the speed-change operating member acts continuously, and control means for controlling said actuator,
It is provided in contact with the driven member, and rotates together with the shift pedal around the second rotation axis to allow rotation of the driven member by the actuator, and sets the operation limit position of the shift operation member. A swingable member that can be set,
The swinging member, when the shift pedal is in the non-operating position, as before Symbol shift operating member against the driving force of the actuator is held in the neutral position, the neutral reference position the driven member as a neutral holding portion for maintaining, the previous SL change pedal when it is depressed, to expand the amount of rotation of from the neutral reference position of the driven member larger the depression amount of the shift pedal, the driven A restricting portion that allows the member to rotate to a position corresponding to the operation limit position, and
When the driven member is located at the neutral reference position, the neutral holding portion is in a state orthogonal to the rotatable direction of the driven member and in a state orthogonal to a line toward the second rotation axis. A work vehicle configured to contact the driven member . The continuously variable transmission is, Hayashi increase the forward speed by the operation of the forward side from the neutral position of the speed-change operating member is configured to accelerated the reverse speed by the operation to the reverse side from the neutral position,
The control means continuously applies a driving force to the forward or reverse side with respect to the speed change operation member based on one of a forward signal and a reverse signal output from the traveling direction setting means by human operation. To drive the actuator,
The follower member is configured to pre-advance side or the speed-change operating member is rotationally displaced to the reverse side so as to pivot actuation,
The restricting portion, and a forward-side regulating unit for setting the operation limit position to the forward side of the driven member, and a reverse-side regulating unit for setting the operation limit position to the reverse side of the driven member, is provided ,
The neutral holding part is constituted by a first part corresponding to the neutral reference position in the forward side restricting part and a second part corresponding to the neutral reference position in the reverse side restricting part,
The first part and the second part are configured to face each other in a parallel state,
The work vehicle according to claim 1 , wherein the driven member is sandwiched between the first portion and the second portion in a state where the driven member is located at the neutral reference position .   Maintenance means for maintaining a state in which the driving force acts on the speed change operation member by escaping a part of the driving force acting on the speed change operation member from the actuator while the speed change operation member is in the operation limit position; The work vehicle according to claim 2 provided.   The actuator comprises a double-acting hydraulic cylinder, a control valve for controlling the hydraulic oil supplied to the hydraulic cylinder by the maintaining means, and a relief valve for releasing the pressure of an oil passage for supplying the hydraulic oil to the hydraulic cylinder; The work vehicle of Claim 3 comprised by these. An engine for supplying driving force to the continuously variable transmission is provided; when the shift pedal is in a non-operating position, the rotational speed of the engine is reduced, and when the shift pedal is operated from the non-operating position; Comprising speed adjusting means for increasing the rotational speed of the engine,
The speed control means includes an operation amount expansion mechanism that expands an operation amount of the shift pedal and transmits the operation amount to the speed control mechanism of the engine when the shift pedal is depressed from the non-operation position. The work vehicle of any one of 1-4.

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