JPH11303988A - Traveling shift structure of work vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid complication of the shift operation by preventing a shift operating tool from being automatically returned to the low speed side even if a vehicle is temporarily stopped in a case where the engine speed is adjusted to the low engine speed and a vehicle travels at a very low speed. SOLUTION: In the traveling state, when a shift operating tool mechanically interlocked with and connected to a gear shift part of a continuously variable transmission for shifting power to be transmitted from a motor part to a raveling device is operated in the accelerating or decelerating direction, an assist means 23 is operated and controlled so as to apply assist force in the operating direction of the shift operating tool. Moreover, only when the vehicle stopped state is detected and also when the output revolution of the motor part exceeds the set revolution, the low-speed returning operation for operating the assist means 23 is performed so as to operate the shift operating tool to the decelerating side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a continuously variable transmission for changing the traveling power transmitted from a prime mover to a traveling device, and a power on / off mechanism for switching power transmission from the prime mover to the traveling device. Means, a braking device for braking the traveling device, and a speed increasing direction and a deceleration direction operation of a speed change operation device which is mechanically operatively connected to a speed change portion of the continuously variable transmission and which is artificially operated in reverse. Assist means for providing an assisting force to the vehicle, operation state detecting means for detecting that the speed change operation tool is being artificially operated and the operation direction thereof, and the shift operation based on the detection information of the operation state detection means. Control means for operating the assist means so that an assist force is applied in the operation direction of the operating tool; and a vehicle stopped state in which the power on / off means is operated in the off state and the braking device is operated in the braking operation state. The related travel gear structure of the working vehicle and a power on-off means to operate the computer enters a and the braking device a universal switching operation by manual operation on the traveling state of manipulating the brake releasing state switching operating member is provided.

[0002]

2. Description of the Related Art The traveling speed change structure of a working vehicle such as a combine for harvesting and harvesting is disclosed in, for example, JP-A-9-3035.
As disclosed in Japanese Patent Application Publication No. 53-53, it is detected that a shift operation tool of a continuously variable transmission that shifts power from a driving unit such as an engine to a traveling device is manually operated in one of speed increasing and decelerating directions. Then, the assist means (electric motor) is controlled so as to actuate an assist force in the speed increasing or decelerating direction to the speed change operation tool. On the other hand, when the vehicle is stopped by manually operating a switching operation tool such as a stepping pedal to stop the vehicle, the power on / off means such as a clutch is turned off, and the brake, that is, the braking device is turned off. When the shift operation device is operated to the high speed side when the pedal is released and the pedal is depressed, the brake is released and the brake is released. When the switching operation tool is operated to stop the vehicle body, the assist means (electric motor) is actuated to change the speed. The operating tool is automatically returned to a low speed side (for example, a neutral position).

[0003]

For example, in a combine or the like, when the engine speed is adjusted to a low speed by an accelerator lever, a pedal or the like is used when traveling over a row or loading / unloading a truck at a very low speed. There are cases in which the vehicle body is temporarily stopped by operating the switching operation tool a number of times, but in the above-described conventional technology, the shift operation tool is automatically moved to a lower speed side (for example, a neutral position) every time the vehicle body is stopped. Since the return operation is performed,
Next, when running the vehicle body, an operation of returning the speed change operation tool to the high-speed side is always required, and therefore, the speed change operation is complicated and operability is deteriorated.

The present invention has been made in view of the above circumstances, and has as its object to solve the problems of the prior art in a case where the engine speed is adjusted to a low speed and the vehicle is driven at a low speed. The object is to prevent the shift operation tool from automatically returning to the low speed side even when the vehicle body temporarily stops.

[0005]

According to the first aspect of the present invention, in the traveling state in which the power transmission from the prime mover to the traveling apparatus is operated and the braking device for braking the traveling apparatus is operated in the brake release state, When a speed change operation device mechanically interlocked with a transmission portion of a continuously variable transmission that changes the power for traveling transmitted from a driving portion to a traveling device is operated in a speed increasing or decelerating direction, the operation state is changed. The detection is detected, and the operation of the assist unit is controlled so as to apply the assist force in the operation direction of the shift operation tool. Further, a vehicle stop state in which the power transmission from the driving unit to the traveling device is turned off and the braking device is operated in the braking operation state is detected, and the detected output rotation speed of the driving unit is the set rotation speed. Is exceeded, a low-speed return operation is performed in which the assist means is operated to operate the speed change operation tool on the deceleration side. If the output rotation speed is equal to or less than the set rotation speed, the low speed return operation is not performed.

Therefore, when the output speed of the driving portion such as the engine is increased and exceeds the set speed, the shift operation tool is forcibly returned to the low speed side as the vehicle body is stopped. Therefore, for example, when the vehicle body is stopped during work traveling or the like and then returned to the traveling state, it is possible to appropriately avoid problems such as sudden jumping of the vehicle body.
On the other hand, when the output rotation speed of the driving unit such as the engine does not exceed the set rotation speed, by preventing the low-speed return operation from being performed even when the vehicle body is stopped, for example, in a work vehicle such as a combine vehicle. When the engine speed is adjusted to a very low speed that does not exceed the set speed, when running over ridges or loading / unloading to trucks, etc. Therefore, the operation of returning the shift operation tool to the high-speed side position before the stop becomes unnecessary. Therefore, in the related art in which the low-speed return operation is performed even in the very low-speed state, the vehicle body is temporarily stopped, and then the vehicle body is run next. Occasionally, it is necessary to return the speed change operation tool returned to the low speed side to the high speed side position before the stop, and the operability of the speed change operation can be improved as compared with the case where the speed change operation becomes complicated.

According to a second aspect, in the first aspect, when the vehicle body stop state is detected and it is determined that the driving unit is in the starting state, the output rotation speed of the driving unit is set to the set rotation speed. Even if the number is less than or equal to the number, the low-speed return operation is performed. Therefore, when the driving unit such as the engine is started, the shift operation tool is forcibly returned to the low speed side as the vehicle body is stopped, regardless of the output rotational speed. Thus, the speed change operation tool can be smoothly shifted from the low speed side to the high speed side, so that the preferable means of the first aspect is obtained.

According to a third aspect, in the first or second aspect, the operation region of the speed change operation tool is provided with a forward region and a reverse region respectively on both sides of the neutral position, and each of the forward region and the reverse region is provided. In the case where the speed change operation device is operated in a direction away from the neutral position, the continuously variable transmission is accelerated, and when operated in a direction approaching the neutral position, the continuously variable transmission is decelerated, and the traveling state is changed to the forward state. A forward / reverse switching mechanism for switching to the reverse state is provided by a shift operation tool so as to be freely switchable at a neutral position, and the control means is configured to operate the shift operation tool in any of a forward area and a reverse area. However, if the vehicle body stop state is detected, the assist means is operated to operate the shift operation tool toward the neutral position.

Therefore, the forward operation state and the reverse state are switched by the switching operation at the neutral position by the speed change operation tool,
When the shift operation tool is operated in a direction away from the neutral position in the forward movement region, the speed increasing device is in the forward side acceleration state, and when the speed change operation device is operated in the direction away from the neutral position in the reverse movement region, the reverse operation is in the speed increasing state. The above-described low-speed return operation can be performed even if the speed change operation tool is operated to the forward or reverse high-speed position, while the forward / backward speed increase / deceleration operation can be performed by simply operating the neutral position in different directions. Can be executed, and the preferable means of claim 1 or 2 can be obtained.

According to a fourth aspect, in any one of the first to third aspects, the operation state detecting means includes a pressure-sensitive sensor for detecting a deceleration operation and a pressure-sensitive sensor for detecting a speed-up operation. Is arranged in a mechanically linking mechanism between the speed change operation tool and the speed change portion of the continuously variable transmission so as to be pressurized by the operation of the speed change operation tool. The operation state of the speed change operation tool can be detected with a simple configuration in which a pair of pressure-sensitive sensors that detect the operation state by being pressed are provided in the mechanical linkage mechanism. The preferred means of any one of the above is obtained.

According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the continuously variable transmission is constituted by a belt-type continuously variable transmission. The speed change structure can be simplified as compared with the case of a step transmission, and the preferable means according to any one of claims 1 to 4 can be obtained.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A traveling speed change structure for a working vehicle according to the present invention will be described below with reference to the drawings when applied to a combine as a working vehicle. FIG. 3 shows a power transmission system of a combine, which is an example of a working vehicle, in which power from an engine 1 as a driving unit is transmitted to a threshing device 46 via a belt tensioning threshing clutch 45 and a tension clutch. Input pulley 4 of a belt-type continuously variable transmission 3 via a belt transmission mechanism 2 having
And the power from the continuously variable transmission 3 is transmitted to the left and right crawler traveling devices 6 via the transmission case 5. That is, the continuously variable transmission 3 corresponds to the continuously variable transmission 3 that shifts the traveling power transmitted from the engine 1 to the traveling device 6.

FIG. 5 shows a transmission structure in the transmission case. The power of the continuously variable transmission 3 is transmitted from the output shaft 60 to the first transmission shaft 61, the input gear 62 of the hydraulic forward clutch FC, and the input gear 63 of the hydraulic reverse clutch RC.
Are transmitted in order. The output gears 64 and 65 of the forward clutch FC and the reverse clutch RC are engaged with the input gear 67 of the second transmission shaft 66. That is, when hydraulic fluid is supplied to the forward clutch FC and the hydraulic clutch is engaged, the first transmission shaft 61
Is transmitted to the second transmission shaft 66 in the forward state via the input gear 62, the forward clutch FC, and the output gear 64. Conversely, when hydraulic oil is supplied to the reverse clutch RC and the hydraulic oil is turned on, the power from the first transmission shaft 61 is transmitted through the input gears 62 and 63, the reverse clutch RC, and the output gear 65 in the reverse reverse reverse state. The power is transmitted to the second transmission shaft 66.
As described above, the forward / reverse switching mechanism B for switching the traveling state between the forward state and the reverse state is constituted by the forward clutch FC and the reverse clutch RC.

A shift gear 68 is externally slidably fitted to the second transmission shaft 66 in a spline structure, and a high speed gear 70, a medium speed gear 71 and a low speed gear 72 are fixed to the third transmission shaft 69. Have been. As a result, the shift gear 68 is slid to engage the high-speed gear 73, the medium-speed gear 71, or the low-speed gear 72 that meshes with the high-speed gear 70, thereby shifting the power to three stages of high, medium, and low. To the transmission gear 75. This configuration corresponds to the auxiliary transmission. Right and left side gears 77 are rotatably fitted to a support shaft 76 that supports the transmission gear 75, and input gears 79 of left and right axles 78 are always engaged with the left and right side gears 77. Support shaft 76
A multi-plate type side brake 80 is provided between the left and right side gears 77 and the transmission case 5 at both left and right ends of the transmission gear 7 by a spring 81.
5 is urged to the occlusal side.

When the left and right side gears 77 are engaged with the transmission gear 75, the power from the third transmission shaft 69 is transmitted to the left and right crawler type traveling device 6 via the transmission gear 75 and the left and right side gears 77. The aircraft runs straight. Then, after the right or left side gear 77 is separated from the transmission gear 75 and the side clutches C and C are disengaged and then the side brake 77 is pressed and operated by the side gear 77, one of the traveling devices 6 is braked. The aircraft will make a pivot turn.

A gear pair 82 having a pair of large and small gears is externally fitted to the first transmission shaft 61 so as to be relatively rotatable, and the large-diameter gear of the gear pair 82 is connected to the output gear 64 of the forward clutch FC.
Is biting. A shift gear 85 is externally slidably fitted to an output shaft 84 that supports an output pulley 83 that transmits power to the mowing unit 8 in the front part of the machine body by a spline structure. By engaging the gears with the large-diameter and small-diameter gears, the power to the mowing part is shifted in two stages, high and low.

Next, a pair of hydraulic cylinders 86 for operating the body by sliding the left and right side gears 77 independently and an entire hydraulic circuit in the switching operation of the forward / reverse switching mechanism B will be described. As shown in FIG. 6, hydraulic oil from one of the pumps 87, 88 driven by the engine 1 is supplied via a flow priority valve 89 (excess flow side) and a first switching valve 90. A variable relief valve 91 is connected between the flow priority valve 89 and the first switching valve 90. The hydraulic oil on the control flow side of the flow priority valve 89 is supplied to the forward clutch FC and the reverse clutch RC via the second switching valve 92, and the forward clutch FC and the reverse clutch RC are supplied to the second switching valve 92. A relief valve 93 for securing the RC pressure is connected. Second switching valve 9
Reference numeral 2 is linked so as to be switched by an operation of the shift lever 26 of the continuously variable transmission 3 at a neutral position, as described later.

The return oil from the relief valve 93 forms an oil passage to be used as lubricating oil for the friction plates of the forward and backward clutches FC and RC. To use as a lubricant,
Since a pressure of about 0.1 to 0.3 kg / cm ² is required,
A relief valve 94 for ensuring pressure is provided in the oil passage b. In the figure, 95 is an accumulator, and in the figure, 96 is
It is interposed in a pressure oil supply path from the hydraulic pump 87 to the flow priority valve 89,
This is an unload valve for returning the pressurized oil from C and RC to the oil tank T to stop traveling of the combine. That is, the forward / reverse clutches FC and RC constitute power on / off means for turning on / off the power transmission from the engine 1 to the traveling device 6.

The unloading valve 96 is linked to a pedal operating tool 97, and if the pedal operating tool 97 is operated with an operating force enough to switch the valve, it can be easily switched to a running stop state. . Further, a parking brake 98 as a braking device for braking the traveling device 6 is also linked to the pedal operating tool 97, and the traveling is stopped by operating one pedal operating tool 97 and the parking brake 98 is activated. The vehicle can also be stopped. In other words, when the vehicle is stopped by a light stepping, the parking brake 98 is pressed by a strong step.
Will work. The safety switch 9 detects that the pedal operation tool 97 has been strongly depressed.
9 are provided.

As described above, the vehicle body stopped state in which the forward / reverse clutches FC, RC are operated to be in the off state and the parking brake 98 is operated in the braking operation state, and the forward / backward clutches FC, RC are operated in the on state and the parking brake 98 is in effect. A switching operation tool which can be freely switched by a manual operation between a running state where the brake is released and a running state is configured by the pedal operation tool 97,
A stop detecting means for detecting whether or not the vehicle is in a stopped state is constituted by the safety switch 99.

Next, the belt-type continuously variable transmission 3 and its shift operation structure will be described. As shown in FIG. 2, the continuously variable transmission 3 includes a first split pulley 11 on the input shaft 9 to which the input pulley 4 is fixed, a second split pulley 12 on the output shaft 10, and a first and a second pulleys. A transmission belt 13 is wound around the split pulleys 11 and 12. The first and second split pulleys 11 and 12 are respectively composed of pulley portions 14 and 14 formed integrally with the input shaft 9 and the output shaft 10 and pulley portions 15 and 15 movable in the axial direction. The movable pulley portion 15 of the second split pulley 12 is urged by a spring 16 toward the fixed pulley portion 14, and the movable pulley portion is proportional to the load on the output shaft 10. Cam mechanism 1 which pushes the pulley 15 against the fixed pulley portion 14
7 are provided.

A ring member 18 is externally fitted to the moving pulley portion 15 of the first split pulley 11 via a bearing.
A pair of pins 18a fixed to the ring member 18 enter the concave portion 19 on the case side of the continuously variable transmission 3 in a state where the roller 18b is rotatably fitted around the outer periphery thereof, and the ring member 18 is recessed. The input shaft 9 is prevented from rotating along the axis 19 along the axis of the input shaft 9. A cylindrical cam member 20 is externally fitted on the input shaft 9 via a bearing. As shown in FIG.
A pair of recesses formed by a linear bottom portion 20a and a pair of left-right symmetric inclined surfaces 20b is formed, and the ring member 1 is formed.
The roller 18b of the eighth pin 18a enters the pair of recesses of the cam member 20. This pin 18a and the roller 1
8b corresponds to the contact guide SO.

2 and 4, the moving pulley portion 15 of the first split pulley 11 is farthest to the left from the fixed pulley portion 14 in the drawing, and the moving pulley portion of the second split pulley 12 In this state, the portion 15 is at the lowest speed position closest to the pulley portion 14 on the fixed side. When the cam member 20 is rotated in either the forward or reverse direction from this state, the contact guide portion SO rides on the inclined surface 20b, and the ring member 18 and the pulley portion 15 on the moving side of the first split pulley 11 move to the fixed side. Of the power transmission belt 13 at the first split pulley 11 is increased. Accordingly, the moving pulley portion 15 of the second split pulley 12 moves away from the fixed pulley portion 14 to the right in the drawing, and the continuously variable transmission 3 is shifted to a higher speed.

The cam member 2 is provided outside the continuously variable transmission 3.
The boss member 21 is fixed to the end of the “0”, and the sector gear 22 is fixed to the boss member 21. Also, as shown in FIG.
An electric motor 23 is fixed to a fixed portion of the body, and a reduction mechanism 24 using a flat gear is provided on the electric motor 23. A pinion gear 24 a of the reduction mechanism 24 is engaged with the sector gear 22. A ring member 25 is fitted around the boss member 21 in a freely rotatable manner, and a speed change lever 26 (corresponding to a speed change operation tool) manually operated on the ring member 25 is connected to the input shaft 9.
Are supported so as to be rotatable integrally about the axis of the shaft, and to be relatively swingable in the left-right direction in FIG. 1 (the front-rear direction in FIG. 2). The pin 25 b of the arm 25 a of the ring member 25 is inserted into the opening 22 a of the sector gear 22, and this pin 25
The fan-shaped gear 22, that is, the cam member 20 is linked so as to be integrally rotated via the link between the b and the opening 22. That is, the cam member 20 serving as the transmission portion is linked via the mechanical linkage mechanism so as to move integrally with the transmission lever 26, and is configured to be operable in the forward and reverse directions.

As shown in FIG. 8, the operation area of the speed change lever 26 is constituted by separately providing a forward area F and a reverse area R on both sides of the neutral position N, and within the forward area F and the reverse area R. When the shift lever 26 is operated in a direction away from the neutral position N, the continuously variable transmission 3 is increased in speed, and when the shift lever 26 is operated in a direction approaching the neutral position N, the continuously variable transmission 3 is decelerated. It is configured to be. Specifically, the shift lever 26 is swingably operable in the cross direction, and includes a guide groove 44a for forward shift of the lever guide, a guide groove 44c for reverse shift, and an intermediate guide groove 44b forming an operation state switching step portion. The swing operation can be performed along each of them, and in the forward shift guide groove 44a or the reverse shift guide groove 44c, the deceleration side operation direction (the neutral position N
Side operation), the shift lever 26 is forcibly restricted at the position corresponding to the traveling neutral state at the inner edges k of the forward shift guide groove 44a and the reverse shift guide groove 44c. It is configured such that the vehicle is not switched to the running state in the front-rear direction due to the excessive operation.
In addition, even at the highest speed position Rmax in the reverse range R, the reception is restricted by the inner edge of the reverse speed guide groove 44c.

The fan-shaped gear 22 is provided with a pair of rubber-like pressure-sensitive switches 27 and 28 as pressure-sensitive sensors so as to sandwich a pin 25b that enters the opening 22a.
The second switching valve 92 for switching the forward / reverse switching mechanism B between the forward position, the reverse position, and the neutral position includes the sector gear 22.
Guide mechanism 47 and push-pull wire 3
0 is linked to the sector gear 22. That is, the guide lever mechanism 2 guides the transmission lever 2
When the forward / backward switching mechanism B is operated in the forward area F, the forward / backward switching mechanism B is switched to the forward position. When the forward / backward switching mechanism B is operated in the neutral area N, the forward / backward switching mechanism B is switched to the neutral stop position. The position is linked by a push-pull wire 30 so as to switch to the position. That is, the forward / reverse switching mechanism B is provided so as to be switchable at the neutral position N by the shift lever 26.

A potentiometer 41 is mounted on the fixed wall 43 of the continuously variable transmission 3, and a lateral pin 42 a at the tip end of a swing lever 42 extending from the potentiometer 41 is inserted into a long hole 22 b formed in the sector gear 22. Thus, an output corresponding to the speed change state of the continuously variable transmission 3 (the position of the cam member 20) is obtained. That is, the potentiometer 41 constitutes a position detecting means for detecting a shift operation position of the shift lever 26. In addition, before the actual work travel, specifically before shipment on the production line, in the inspection mode described later,
When the shift lever 26 is operated from one end of the operation area toward the other end via the neutral position, one end, the neutral position,
As shown in FIG. 8, the actual detection values of the potentiometers 41 at each of the other end portions are sequentially detected as shown in FIG. 8, a detection value VRm corresponding to the reverse maximum speed Rmax, a detection value Vn corresponding to the neutral position N, and a shift range. As the detected value VFm corresponding to the maximum forward speed Fmax of the vehicle, the respective detected values are stored in a nonvolatile memory M (see FIG. 7) described later, and among them, the detected value VRm (about 0.2 volt) Is set to 0, the detected value VFm (about 4.8 volts) is set to 256 points, and an intermediate potential can be detected in units of one point.

As shown in FIG. 7, a control device 31 for instructing control information for the electric motor 23 is provided. The control device 31 is provided with a microcomputer, and is set in advance based on various input information. A predetermined control is executed by a stored control program. Switching to the forward drive state is performed by the control information from the control device 31 (that is, the shift lever 26 is switched).
The first electromagnetic relay 32 is switched to swing to the forward rotation side which is counterclockwise in FIG. 1), and the first electromagnetic relay 32 is switched to the drive state on the reverse side (that is, the shift lever 26 is moved to the forward rotation side in FIG. 1). The second electromagnetic relay 33, the transistors 35, 36 for exciting the first and second electromagnetic relays 32, 33, and the control signal from the control device 31 are switched. Current adjusting transistor 3 for adjusting the amount of current supplied to electric motor 23 based on
7. A reference resistor 38 for detecting an actual current value flowing through the electric motor 23 as a voltage value between both ends, a voltage between both ends of the reference resistor 38 is converted into a DC signal, and the control device 31 outputs the current detection information to the electric motor 23 as current detection information. Smoothing circuit 3 for input
9 etc. are provided. The reference resistor 38 and the smoothing circuit 39 constitute a current detection circuit as current detection means, and are configured to detect a current value in a detection range of 0 to 5 amps.

The control device 31 includes the pressure-sensitive switches 27 and 28 on the forward rotation side and the reverse rotation side, and the potentiometer 4.
1. Each detected value of the safety switch 99 is input, and detection information of an engine speed sensor 50 as a speed detecting means for detecting the output speed of the engine 1 is input. Here, the engine speed sensor 50
Is composed of an electromagnetic pickup or the like. The detection value (voltage value) of the potentiometer 41 is input to the control device 31 as an analog signal, and the analog signal is applied to the entire stroke range (0.2 volt to
4.8 volts) is analog /
It is digitally converted and used for control.

Next, a shift operation by manual operation of the shift lever 26 will be described. When one of the pressure-sensitive switches 27 and 28 is turned on and the shift lever 26 is detected to be artificially operated in either forward or reverse direction, the control device 31 performs the manual operation. An assist operation current is supplied to the electric motor 23 so that an assist force is applied in the direction, so that the electric motor 23 can appropriately perform a shift operation with a small operation force. Therefore, each pressure-sensitive switch 27,
An operation state detecting means for detecting that the shift lever 26 is artificially operated and its operating direction is constituted by 28. Further, as shown in FIG. The pressure-sensitive sensor 28 and the pressure-sensitive sensor 27 for detecting the speed-up operation are pressurized by the operation of the transmission lever 26 during the mechanical linkage between the transmission lever 26 and the transmission section 20 of the continuously variable transmission 3. It is arranged and arranged in a state where it is performed.

As described above, the electric motor 23 is mechanically connected to the transmission unit 20 of the continuously variable transmission 3 to operate the transmission lever 26 in the speed increasing direction and the deceleration direction that is artificially operated in the forward and reverse directions. Assist means for giving an assist force to the vehicle is constituted. Further, control means for operating the assist means (electric motor 23) is provided by the control device 31 so that an assist force is applied in the operation direction of the shift lever 26 based on the detection information of the operation state detecting means 27 and 28. You.

The control means 31 detects the vehicle stopped state based on the detection information of the safety switch 99 and the engine speed sensor 50, and changes the output speed of the engine 1 to the set speed (1900 rpm). If it exceeds, a low-speed return operation (automatic deceleration processing described later) for operating the electric motor 23 to operate the shift lever 26 to the deceleration side is executed. When executing the low-speed return operation, the control means 31 determines that the shift operation position of the shift lever 26 detected by the potentiometer 41 is located in any of the forward area F and the reverse area R. Even in this case, the electric motor 23 is operated to operate the shift lever 26 toward the neutral position N.

Further, a starting state judging means 100 for judging whether or not the engine 1 is in a starting state is constituted by using the control device 31 (see FIG. 7). Specifically, a switching signal from a power supply main switch (not shown) is input to the control device 31 and the main switch is switched from the off state to the on state. It is determined that the engine 1 is in the starting state until the rotation start is detected and the engine rotation speed reaches the rotation speed for work or the like. When the vehicle stop state is detected and the starting state determining unit 100 determines that the engine 1 is in the starting state, the control unit 31 reduces the output rotation speed of the engine 1 to the set rotation speed. Even when the speed is equal to or less than a number (1900 rpm), the low-speed return operation (automatic deceleration process) is executed.

When it is detected based on the detection information of the pressure-sensitive switches 27 and 28 that the shift lever 26 has not been artificially operated, the continuously variable transmission 3 is returned to the neutral position by the urging force. In order to prevent the shift state from changing,
It is configured to supply a holding current to the electric motor 23. Here, the control device 31 controls each pressure-sensitive switch 2
The supply amount of the holding current is adjusted to an appropriate value based on the detection information of 7, 28 and the detection information of the current detection circuit. Specifically, as the assist operation current, O
A constant voltage is output so as to maintain the N state, and in the supply state of the holding current, the ON / OFF state is intermittently repeated with a pulse voltage for the current adjusting transistor 37,
The ON time is adjusted (duty ratio control) to adjust the amount of current. The forward and reverse operation directions of the electric motor 23 are determined by turning on each of the pressure-sensitive switches 27 and 28 so that one of the electromagnetic relays 32 and 33 is switched to the power supply state and the rotation direction of the electric motor 23 is changed. It is stipulated.

In addition, the pressure-sensitive switches 27 and 28 are used to operate the transmission lever 26 in both the speed-up direction and the deceleration direction. When it is detected that both the forward rotation switch 27 and the pressure-sensitive switch 28 on the reverse rotation side (hereinafter referred to as a reverse switch) are turned on,
The control device 31 operates the electric motor 23 to operate the speed change lever 26 to the deceleration side until reaching the traveling stop position, regardless of the detection information by the pressure-sensitive switches 27 and 28 thereafter. The operation is not performed in the speed increasing direction. Since the state where both switches 27 and 28 are both turned on (both side operation state) is an abnormal state such as a failure of the switch, in such a case, the shift lever 26 is forcibly returned to the neutral position. The operation safety is ensured by not performing the assist operation for speed increase after that.

Next, the control operation of the control device 31 will be described.
This will be described with reference to the flowcharts shown in FIGS. Note that this control flow chart is 1 in 10 msec.
Times and repeatedly. When the control is started, first, it is determined whether or not the engine speed exceeds 500 rpm, that is, whether or not the engine 1 is rotating normally (step 1). When the engine 1 is not rotating, the load at the time of shifting operation is very heavy in the belt continuously variable transmission 3, and when the electric motor 23 is operated in this state, the electric motor 23 and a drive circuit may be damaged. It is. If the engine 1 is rotating, the switching information from the mode switch 29
It is determined whether or not the lever position storage mode has been instructed (step 2). This mode is executed at the factory shipment stage, and is not executed by a normal combine user. When the lever position memory mode is specified,
A lever position storage process is executed (step 3). In this lever position storage process, when the operator moves the shift lever 26 to each of the reverse side highest speed position Rmax, the neutral position N, and the forward side highest speed position Fmax, the detection value of the potentiometer 41 at each operation position is obtained. (VRm, V
n, VFm) is read, written and stored as digital data in the nonvolatile memory M. When the shift lever 26 is moved to each of the above positions, the assist operation by the electric motor 23 is not performed by the maximum assist force but is performed by about 40% when the shift lever 26 is operated toward the forward highest speed position. The operation is performed at the duty ratio, and the traction member 57 is flexed and deformed by a large operation force, and the detection value VFm of the potentiometer 41 at the forward-side highest speed position is erroneously determined at a position deviating from the appropriate upper limit regulating position. The writing and storing are prevented beforehand.

On the other hand, if the mode is not the lever position storage mode, the mode shifts to the manual shift mode. When the speed change lever 26 is operated to the forward rotation side and the forward rotation switch 27 is pressed by the pin 25b to be turned on (step 4), first, as shown in FIG.
It is determined whether or not the state (two-sided operation state) has been reached (step 5). The ON state on both sides continues for 30 minutes.
If it continues for 0 msec or more, it is determined that the switch is in an abnormal state in which the switch has an ON failure, and the shift lever 26 is turned on regardless of the subsequent detection information of the switches 27 and 28.
Actuate the electric motor 23 to move in the deceleration direction (direction toward the neutral position) (steps 6 and 7). When the shift lever 26 is operated to the neutral range N based on the detection information of the potentiometer 41, the electric motor 2
(3), the both terminals of the electric motor 23 are grounded, and the electric motor 23 is not operated based on the detection of the forward rotation switch 27 and the reverse rotation switch 28 (steps 8, 9, 10). ). In this case,
The operator is informed that the operation is abnormal by an informing means such as the display 48 or a buzzer. When the electric motor 23 is grounded on both sides, the operation becomes heavy, but it is possible to operate the transmission lever 26 by manual operation force to perform the speed change operation of the continuously variable transmission 3.

And there is no such both-side ON state.
When the forward rotation switch 27 is pressed and turned on, based on the detection information of the potentiometer 41, the transmission lever 2 is turned on.
If the operation position of No. 6 is not the forward upper limit position Fmax or the neutral region N and 200 msec or more has elapsed since the operation on the reverse rotation side has been completed, the assist operation current is supplied to the electric motor 23.
At high speed to the forward rotation side (steps 11, 12, 1).
3). That is, the transistor 37 is continuously turned on, and the electric motor 23 is operated with the maximum assist force. Further, as shown in FIG. 11, when the reverse rotation switch 28 is turned on, the electric motor 23 is driven to the reverse rotation side at a high speed in the same manner as in the case of the normal rotation switch 27 (steps 19 to 23).

When the speed change lever 26 is in the forward upper limit position Fmax when the forward rotation switch 27 is turned on, or when the speed change lever 26 is in the reverse upper limit position Rmax when the reverse rotation switch 28 is turned on. Does not perform the assist operation by the electric motor 23 (step 1).
1, step 20). In the neutral region N of the transmission lever 26, the transmission lever 26 may come into contact with the inner edge k of the guide groove and cause hunting. Switch 2
8) After the previous ON operation has been completed,
If the operation is performed within 00 msec, the electric motor 23 is operated at a very slow speed until the switch that is being turned on is turned off (steps 12, 15, 16, 16).
17, 18, 21, 24, 25, 26, 27)

In the state where the shift lever 26 is not operated (all switches are OFF), the continuously variable transmission 3 is thereafter held at the current shift position against the neutral return force. In addition, a holding current is supplied to the electric motor 23, and the holding force (operation force for holding) by the electric motor 23, the neutral return force of the continuously variable transmission 3 (the moving urging force of the contact guide SO), and the like. Is held so as to keep the positions balanced (step 28). Although not described in detail, since the above-described neutral return force changes depending on the shift state, a different holding force is initially set according to the shift state, and the detection state of the potentiometer 41 and the detection state of the current detection circuit are determined. Based on the state, the holding current is adjusted to be an appropriate value.

Then, the following automatic deceleration control is executed (step 29). That is, as shown in FIGS. 12 to 14, when the safety switch 99 is turned on in accordance with the depression operation of the pedal operation tool 97, the ON operation is performed by turning on the main switch also serving as the engine start switch. This is the first operation (that is, the engine 1 is in the starting state) after the power supply to the electrical devices of the combine is started, or the first operation is not the first operation. Engine speed Ne is 1900r
pm, and when it is confirmed that the detection value of the potentiometer 41 is within the appropriate detection range and is normal, a deceleration operation described later is executed (steps 30 and 31). , 32, 33). If the safety switch 99 is not turned on, the engine speed is not higher than 1900 rpm, the operation is not performed, and if the detection value of the potentiometer 41 is not within the proper detection range and the operation is abnormal, the deceleration is performed. The operation is not performed. The determination as to whether or not the detection value of the potentiometer 41 is within the proper detection range is made when the detection value is 0.
The determination is made based on whether the voltage is between 2 volts and 4.8 volts, that is, whether a disconnection or a short circuit has occurred.

When the pedal operating tool 97 is operated, the shift lever 2 is operated based on the detection information of the potentiometer 41.
If 6 is in the high speed range F1, R1 (see FIG. 8) in the forward range or the reverse range, the operating current is supplied to the electric motor 23,
A deceleration operation of moving the shift lever 26 slowly in the deceleration direction (direction toward the neutral position) toward the neutral region N is executed (steps 34 and 35).

If the speed change lever 26 is in the first slow speed range F2 or R2 (see FIG. 8) in the forward or reverse range, the deceleration operation is basically performed. When it is detected that the lever 26 has been manually operated in the speed increasing direction, the deceleration operation is stopped at that time, and thereafter, if there is a lever operation to the deceleration side, the deceleration operation is executed accordingly (step 34). To 39).

If the speed change lever 26 is in the forward or reverse second slow speed range F3, R3 (see FIG. 8), the deceleration operation is basically continued. When it is detected that the shift lever 26 has been manually operated in the speed increasing direction, the deceleration operation is stopped at that time, and thereafter, if there is a lever operation to the deceleration side, the deceleration operation is executed in accordance therewith. If there is a lever operation to the high speed side, the speed increasing operation will be executed accordingly (steps 42 to 4).
9).

When the speed change lever 26 enters the neutral range N, the deceleration operation is stopped, and if there is a lever operation to the deceleration side, the deceleration operation is executed accordingly, and the deceleration operation is performed. If there is a lever operation, the speed increasing operation is executed accordingly (steps 42, 45 to 49).

The above-described deceleration operation is executed while the safety switch 99 is ON, that is, while the pedal operation tool 97 is being depressed, and the safety switch 99 is turned off or the engine rotation is stopped. When the number becomes 1900 rpm or less, the deceleration operation is stopped, and the process returns to step 1.

[Other Embodiments] (1) In the above embodiment, a belt-type continuously variable transmission is used as the continuously variable transmission 3 and the forward / reverse switching device is switched by a switching operation at the neutral position of the transmission lever. ,
Although the case where the forward / reverse speed change operation can be performed by operating the shift lever has been exemplified, a hydrostatic continuously variable transmission (HST) may be used instead of this configuration, and a friction type continuously variable transmission may be used. Good. In addition, the present invention can be applied to a continuously variable transmission device provided in a transmission system in a constant rotation direction, that is, a speed change operation structure that performs only acceleration / deceleration, instead of a device capable of increasing / decreasing operations in forward and backward directions by operating a shift lever. .

(2) In the above embodiment, the power on / off means is constituted by the forward clutch FC and the reverse clutch RC. However, a clutch or the like provided at another place in the transmission system may be used.

(3) In the above embodiment, the braking device is constituted by the pair of left and right side brakes 80. However, other than this, for example, a braking device acting on the axle may be used.

(4) In the above embodiment, the electric motor is used as the assist means. However, a drive mechanism using a hydraulic motor or a driving force of an engine may be used.

(5) In the above embodiment, the operation state detecting means is constituted by a pair of pressure-sensitive switches.
It may be constituted by a limit switch or by using an optical sensor.

(6) In the above embodiment, the switching operation tool is
Although it consisted of the pedal operation tool 97 operated by the foot,
Instead of such a configuration, a hand-operated lever or the like may be used.

(7) In the above embodiment, the stop detection means is constituted by the safety switch 99 for detecting that the pedal operating tool 97 is depressed. However, instead of such a constitution, the forward clutch FC or the like may be used. The clutch operating state and the operating state of the parking brake 98 may be directly detected.

(8) In the above embodiment, the rotation speed detecting means 50 is constituted by the electromagnetic pickup type rotation speed sensor 50. However, instead of such a structure, a means for detecting the output frequency of the dynamo may be used. .

(9) In the above embodiment, the starting state determination means 100 is configured using the control device 31. However, other configurations may be used.

[Brief description of the drawings]

FIG. 1 is a side view showing a shift operation configuration.

FIG. 2 is a sectional view of the belt continuously variable transmission.

FIG. 3 is a diagram showing a transmission system of the combine.

FIG. 4 is a side view of a cam mechanism.

FIG. 5 is a diagram showing a transmission structure in a transmission case.

FIG. 6 is a configuration diagram of a hydraulic circuit for traveling operation.

FIG. 7 is a block diagram of a control configuration.

FIG. 8 is a diagram showing an operation range of a shift lever.

FIG. 9 is a flowchart of a control operation.

FIG. 10 is a flowchart of a control operation.

FIG. 11 is a flowchart of a control operation.

FIG. 12 is a flowchart of a control operation.

FIG. 13 is a flowchart of a control operation.

FIG. 14 is a flowchart of a control operation.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 drive unit 3 continuously variable transmission 6 traveling device 20 transmission unit 23 assist means 26 speed change operation tool 27, 28 operation state detection means 27 pressure-sensitive sensor 28 pressure-sensitive sensor 31 control means 41 position detection means 50 rotation speed detection means 80 braking Device 97 Switching operation tool 99 Stop detecting means 100 Starting state determining means B Forward / reverse switching mechanism FC, RC Power on / off means

Claims (5)

[Claims] 1. A continuously variable transmission that changes the power for traveling transmitted from a prime mover to a traveling device, a power on / off means that switches power transmission from the prime mover to the traveling device, and the traveling device And a braking device mechanically interlocked with the transmission portion of the continuously variable transmission to artificially operate the transmission operation device in the forward and reverse directions to provide an assist force for the operation in the speed increasing direction and the speed decreasing direction. An assisting means for giving; an operation state detecting means for detecting that the speed change operation tool is artificially operated and the operation direction thereof; and an operation direction of the speed change operation tool based on the detection information of the operation state detection means. Control means for operating the assist means so that an assist force is applied; a vehicle stopped state in which the power on / off means is operated in an off state and the braking device is operated in a braking operation state; and the power on / off means And a switching operation tool capable of being manually switched between a traveling state in which the vehicle is turned on and a braking state in which the braking device is released. A stop detecting means for detecting whether or not the motor is in a state; and a rotational speed detecting means for detecting an output rotational speed of the prime mover, wherein the control means detects the stop detecting means and the rotational speed detecting means. Based on the information, if the vehicle body stop state is detected, and if the output rotation speed of the prime mover exceeds a set rotation speed,
A low-speed return operation for operating the assist means to operate the speed change operation tool to the deceleration side is performed, and the low-speed return operation is not performed if the output rotational speed is equal to or less than a set rotational speed. The traveling speed change structure of the work vehicle. 2. A starting state determining means for determining whether or not the driving unit is in a starting state, wherein the control means detects the vehicle body stopped state, and
When the starting state determination unit determines that the driving unit is in the starting state, the low-speed return operation is performed even when the output rotation speed of the driving unit is equal to or less than the set rotation speed. The traveling speed change structure for a working vehicle according to claim 1, wherein the traveling speed change structure is configured. 3. A position detecting means for detecting a shift operation position of the speed change operation tool, wherein an operation area of the speed change operation tool is provided with a forward area and a reverse area separately on both sides of a neutral position, In each of the forward movement region and the reverse movement region, when the speed change operation tool is operated in a direction away from the neutral position, the continuously variable transmission is accelerated, and when operated in a direction approaching the neutral position, The continuously variable transmission is configured to be decelerated, and a forward / reverse switching mechanism that switches a traveling state between a forward state and a reverse state is provided so as to be freely switchable at the neutral position by the shift operation tool. When performing the low-speed return operation, the shift operation position of the shift operation tool detected by the position detection unit is located in any of the forward region and the reverse region. It also works vehicle travel gear structure of the speed change operation member to the neutral position side to be configured to activate the assist unit in order to operate is to have claim 1 or 2, wherein. 4. The machine according to claim 1, wherein said operation state detecting means includes a pressure-sensitive sensor for detecting a deceleration operation and a pressure-sensitive sensor for detecting a speed-up operation. A pressure link is provided in the target link mechanism in a state where the pressure is applied by operating the speed change operation tool.
4. The traveling speed change structure for a working vehicle according to claim 3. 5. The traveling speed change structure for a working vehicle according to claim 1, wherein the continuously variable transmission is a belt-type continuously variable transmission.