JPH10114234A - Gear shift operation structure of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform continuance of smooth operation prevented from the occurrence of hunting even when a gear shift lever is interfered with other object. SOLUTION: A gear shift operation structure of a working vehicle is formed such that by utilizing an electric motor 23 for controlling a car speed for a continuously variable gear shifter 3, artificial operation of a gear shift lever 26 is detected by a pressure-sensitive switches 27 and 28 assist operation of artificial gear shift operation is executed. In this case, a potentiometer 41 is provided to detect the operation position of the gear shift operation tool 26. Based on detecting information of the pressure-sensitive switches 27 and 28 and detecting information of a potentiometer 41, it is discriminated whether, during execution of control of a car speed, the gear shift lever 26 is interfered with an external object and the pressure-sensitive switches 27 and 28 effect erroneous detection. When it is discriminated that interference is effected, operation of the electric motor 23 based on car speed control is executed in succession in spite of detecting information of the pressure-sensitive switches 27 and 28.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an actuator for continuously changing the speed of a speed change portion of a continuously variable transmission for traveling, control means for controlling the actuator, and mechanically interlockedly connected to the speed change portion. An operation detecting means for detecting whether or not the shift operation tool which can be manually operated in the direction is artificially operated, and an operation direction thereof, wherein the control means is an engine detected by the load detecting means; Based on the vehicle speed control controlling the actuator and the detection information of the operation detecting means, the assist force is generated in the forward and reverse directions along the operation direction of the shift operation tool so that the load of the target load becomes the target load. And an assist control for controlling the actuator, and a work vehicle configured to execute the assist control prior to the vehicle speed control. Speed operation structure for.

[0002]

2. Description of the Related Art A shift operation structure of a work vehicle having the above-described structure is used for a manual shift operation based on an artificial operation using an actuator for a shift operation for controlling a vehicle speed based on detection information of an engine load. An assisting force by the actuator is applied in the operation direction in accordance with the operation, so that the manual operation can be easily performed.

Conventionally, in this type of shift operation structure, a manual shift operation, that is, the assist control is always performed prior to the vehicle speed control in consideration of running safety. Had become. For example, when the vehicle speed control is executed and the vehicle speed is increased, and when the speed change operation tool is artificially operated to the deceleration side, it is determined by the operation detecting means that In this case, the assist control is executed with priority, and the continuously variable transmission is shifted to the deceleration side.

[0004]

When the vehicle speed control is executed, the speed change operation tool is operated because the transmission section of the continuously variable transmission and the speed change operation tool are linked to each other. Will be moved in conjunction with
For example, if the speed change operation tool interferes with another object in the middle of the operation area and its movement is obstructed, the interference with such another object causes the speed change operation tool to artificially change the operation direction based on the vehicle speed control. A state similar to the state operated in the reverse direction will occur.

[0005] Other objects that interfere with such a shift operation tool include the following. For example, it is necessary to insert a guide elongated hole formed in a cover body that covers a continuously variable transmission or the like so that the speed change operation tool can be manually operated and exposed to the outside of the cover body. Generally, a dust-proof member made of an elastic material such as rubber is provided to prevent dust and foreign matter from entering, but this dust-proof member may be turned up and hinder operation of the speed change operation tool. In addition, flexible electric wiring or hydraulic piping may be provided by utilizing the narrow space inside the cover body, and such electric wiring and various piping may interfere with the shift operation tool. There is.

As a result, due to such interference with other objects, the operation detecting means detects that the speed change operation tool has been operated in the opposite direction to the operation direction based on the vehicle speed control.
The assist control is executed with priority, and the actuator is operated to shift gears in the reverse direction. However, at this time, since the speed change operation tool is not manually operated, if the shift operation tool is operated in the opposite direction to a position where interference between the speed change operation tool and another object is canceled, then, operation detection is performed. The means switches to the non-detection state and switches again to the vehicle speed control state. Thereafter, such a state is repeated, so that there is a disadvantage that a so-called hunting phenomenon occurs.

The present invention has been made by paying attention to the fact that other objects that interfere with the above-mentioned speed change operation tool are flexible members, elastic materials, and the like. The problem is that the inconvenience of the shift operation caused by such interference is avoided beforehand.

[0008]

According to the first aspect of the present invention, it is determined whether or not the shift operation tool has been artificially operated and the operation direction thereof is detected by the operation detection means. The operation position of the speed change operation tool is detected by the position detection means, and the control means, based on the detection information of the operation detection means and the detection information of the position detection means, detects that the speed change operation tool It is determined whether or not the operation detection means has erroneously detected due to interference. Then, when it is determined that there is interference, the operation of the actuator based on the vehicle speed control is continuously executed regardless of the detection state of the operation detection means.

Therefore, during the execution of the vehicle speed control, the speed change operation tool interferes with another object, so that the operation detection means detects that the operation has been artificially performed in the direction opposite to the operation direction at that time. However, in this interference position, the operation can be forcibly executed continuously by continuously operating the actuator based on the vehicle speed control, and the hunting caused by the interference with another object can be performed. The shift operation can be performed without any disadvantage such as occurrence of a phenomenon.

According to a second aspect of the present invention, when the vehicle speed control is being executed, the control means causes the operation detecting means to change the speed in the direction opposite to the operation direction by the operation of the actuator based on the vehicle speed control. When it is detected that the operating tool has been manually operated, the detected value of the position detecting means at that time is stored. If the stored value of the position detecting means is the same or almost the same as the stored value stored last time, it is determined that the speed change tool interferes with an external object and the operation detecting means has erroneously detected. Will be.

That is, if the speed change operation tool interferes with another object while the vehicle speed control is being performed and the speed change operation is being performed by the actuator, the movement is blocked at that position.
It is detected by the operation detecting means that the speed change operation tool is manually operated in the opposite direction, and furthermore,
Since the detection position is always the same or almost the same position, the operation position is stored and compared with the previously stored value to determine whether the shift operation tool is interfering with an external object. You can.

According to the characteristic configuration of the third aspect, when the control means determines that the speed change operation tool is interfering with an external object, the control means sets the shift operation tool from an operation direction upper side than the interfering operation position. Until the operation position is exceeded, the vehicle speed control is executed prior to the assist control.

Therefore, even if the speed change operation tool interferes with an external object and is detected by the operation detection means as being operated, regardless of the detection state, the vehicle speed control is performed at the interfering portion. Is executed prior to the assist control, so that the operation by the actuator can be forcibly executed continuously based on the vehicle speed control regardless of the detection state of the operation detecting means, and the interference with another object is caused. The speed change operation can be executed in a state without disadvantage such as occurrence of a hunting phenomenon.

According to a fourth aspect of the present invention, when the control means determines that the speed change operation tool is interfering with an external object, the control means operates the actuator based on the vehicle speed control. An operation signal is output so as to increase the operation force of the actuator from a position farther in the operating direction than the interfering operation position to a position exceeding the operation position.

Therefore, the actuator is operated with a large operating force from a position farther in the operating direction than the interfering operation position to a position beyond the operation position, so that an interference state with another object can be reduced with a sufficient operation force at the interference portion. Operation can be forcibly avoided.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 4 shows a power transmission system of a self-removing type combine, which is an example of a work vehicle, in which power from an engine 1 is transmitted to a belt transmission mechanism 2 having a tension clutch.
The power from the continuously variable transmission 3 is transmitted to the input pulley 4 of the belt-type continuously variable transmission 3 through a hydraulic clutch type forward / backward switching device (not shown) in the transmission case 5 and traveling. To the right and left crawler traveling devices 6 via a gear transmission (not shown) for the vehicle. The power separated from immediately before the gear transmission is transmitted from the transmission case 5 to the reaping unit 8 at the front of the machine body via the belt transmission mechanism 7. The power of the engine 1 is also transmitted to a threshing device 46 via a threshing clutch 45.

Next, the configuration of the belt-type continuously variable transmission 3 will be described. As shown in FIG.
The first split pulley 11 and the output shaft 1
A second split pulley 12 is provided at 0 and a transmission belt 13 is wound around the first and second split pulleys 11 and 12.
The first and second split pulleys 11 and 12 have a pulley portion 1 fixed to the input shaft 9 and the output shaft 10 in a spline structure.
4 and a pulley portion 15 that is 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 output shaft 10. A cam mechanism 17 is provided which pushes the pulley portion 15 on the moving side to the pulley portion 14 on the fixed side in proportion to an increase in the load on the side.

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 recess 19 on the case side of the continuously variable transmission 3, and the ring member 18 is prevented from rotating. As shown in FIGS. 3 and 2, a cylindrical cam member 20 is externally fitted to the input shaft 9 via a bearing, and has a recess formed by a linear bottom portion 20a and a pair of right and left symmetric inclined surfaces 20b. Are formed on the cam member 20, and the rollers 18 b of the pins 18 a of the ring member 18 enter the pair of recesses of the cam member 20.

In the state shown in FIGS. 2 and 3, the movable 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 movable pulley portion of the second split pulley 12 is moved to the left. 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 right and left from this state, the pulley portion 15 on the moving side of the ring member 18 and the first split pulley 11 is pushed through the inclined surface 20b toward the pulley portion 14 on the fixed side. And the transmission belt 13 at the first split pulley 11
Winding radius increases. Along with this, the pulley portion 15 on the moving side 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. Therefore, the cam member 20 functions as a transmission section of the continuously variable transmission 3.

Next, the operation structure of the belt type continuously variable transmission 3 and the forward / reverse switching device will be described. 2 and 1
As shown in FIG. 2, a boss member 21 is fixed to an end of the cam member 20 outside the continuously variable transmission 3, and a sector gear 22 is fixed to the boss member 21. An electric motor 23 as an actuator is fixed to a fixed portion of the body, and a reduction mechanism 24 using a flat gear is provided in the electric motor 23,
The pinion gear 24 a of the reduction mechanism 24 is engaged with the sector gear 22. A ring member 25 is externally fitted to the boss member 21, and a speed change lever 26 (corresponding to a speed change operation tool) is externally fitted to the ring member 25 so as to be relatively rotatable.

The shift lever 26 is swingably movable in the cross direction. As shown in FIG. 5, a guide groove 44a for forward shift and a guide groove 44c for reverse shift of the lever guide formed on the cover body CA are provided. The swing operation can be performed along each of the intermediate guide grooves 44b forming the step portion for state switching, and when the operation is performed along the deceleration side operation direction in the guide groove 44a for forward shift or the guide groove 44c for reverse shift. , Forward transmission guide groove 44a / reverse transmission guide groove 4
At the inner edge k of 4c, the gearshift lever 26 is forcibly received and restricted at a position corresponding to the traveling neutral state, and is configured so as not to be switched to the traveling state in the front-rear direction by excessive operation.

Then, as shown in FIG.
The guide groove forming portion A is provided with a dust-proof rubber GM in order to prevent dust, moisture and the like from entering the inside through the opening.
Are provided so as to be divided into right and left so that the shift lever 26 can be operated over the entire operation area.

The pin 25 of the arm 25a of the ring member 25
b has entered the opening 22a of the sector gear 22, and a pair of rubber-like pressure-sensitive switches 27 and 28 are connected to the arm 25a.
Is fixed to the sector gear 22 so as to sandwich the pin 25b. A switching valve (not shown) for switching the forward / reverse switching device between a forward position, a reverse position, and a neutral stop position is provided, and the sector gear 22 and the switching valve are connected to the push-pull wire 2.
9 and the accommodation mechanism 30. That is,
When the speed change lever 26 is operated in the forward direction, which is counterclockwise in FIG. 1, the pin 25b contacts the forward-direction pressure-sensitive switch 27, and the detection signal is output from the forward-direction pressure-sensitive switch 27. Is output, and it is detected that the shift lever 26 has been operated to the forward rotation side. When the shift lever 26 is operated in the reverse direction, which is clockwise in FIG. 1, the pin 25b contacts the reverse-side pressure-sensitive switch 28, and a detection signal is output from the reverse-side pressure-sensitive switch 28. And the shift lever 26
Is operated to the reverse rotation side. Therefore, the operation detecting means is constituted by the pressure-sensitive switches 27 and 28.

Then, the shift lever 26 is moved to the neutral stop region N
When the forward-reverse switching device is operated to the forward position by the push-pull wire 29 and the switching valve when the shift lever 26 is operated from the neutral stop position N to the reverse range, the push-pull operation is performed. The forward / reverse switching device is operated to the reverse position by the wire 29 and the switching valve.
With the above configuration, the speed change lever 26 and the cam member 20 are operatively linked in the forward and reverse directions via a contact and link mechanism between the pin 25b and the sector gear 22.

A potentiometer 41 is mounted on the fixed wall 43 on the side of the continuously variable transmission 3, and a lateral pin 42 a at the tip end of an oscillating lever 42 extending from the potentiometer 41 is formed in a long hole formed in the sector gear 22. 22
b, the potentiometer 41 is provided so as to be operated in accordance with the shift operation of the continuously variable transmission 3 so that the shift state of the continuously variable transmission 3 can be detected. The detection value of the potentiometer 41 is A / D converted in 256 steps, and is read into the control device 31 described later. Therefore, the potentiometer 41 corresponds to a position detecting unit. In addition, the determination data for determining the shift position based on the detection value of the potentiometer 41 is obtained by measuring the actually measured value of the potentiometer 41 in advance and storing the measured data in a storage unit such as a memory. Here, the discrimination data divides the swing range of the shift lever 26 into the neutral region N and the forward region F and the reverse region R sandwiching the neutral region N, as shown in FIG. And the neutral region N is defined as an excessively high region Na on both sides of the center neutral position n.
(A set area in the neutral area N) and a pair of starting areas N located on both sides of the excessively steep area Na with an interval.
b (the setting area where the shift lever 26 is located immediately before the start), and the value indicated by the potentiometer 41 is assigned to each area.

As shown in FIG. 7, the drive circuit for driving the electric motor 23 is excited by a signal from the control device 31, and the shift lever 26 swings counterclockwise in FIG. The rotation direction of the electric motor 23 is switched such that the rotation direction of the electric motor 23 is switched and the speed change lever 26 swings clockwise in FIG. A second electromagnetic relay 33 is provided. Electric motor 2 as described above
The first and second electromagnetic relays 32 and 33 for determining the direction of the current supplied to the motor 3 are driven by excitation by transistors 35 and 36, and the power supplied to the electric motor 23 is controlled by a pulse from the controller 31 as described later. It is controlled by a transistor 37 which operates in response to a signal. In addition, a reference resistor 38 for detecting a value of a holding current A2 supplied to the electric motor 23 to be described later and a smoothing circuit 39 for smoothing a voltage between both ends of the reference resistor 38 are provided.

Also, in this combine, when a harvesting operation is performed while the vehicle body is running, the vehicle speed auto switch 5
2 is in the ON state, the stepless step is performed so that the engine load reaches the target load while the upper limit of the vehicle speed does not exceed the upper limit vehicle speed artificially set by the upper limit vehicle speed setting device 51. The vehicle speed control for automatically performing the speed change operation of the transmission 3 is performed. That is, a stock sensor 47 for determining whether or not the harvesting operation is in progress based on the presence or absence of the harvested grain culm conveyed, and a threshing clutch lever 48 for turning on and off the threshing clutch 45.
Threshing switch 49 for detecting that the clutch is engaged, an engine speed sensor 50 as load detecting means for detecting the engine speed, and transmission case 3
A vehicle speed sensor 53 for detecting the running speed of the vehicle body based on the rotation speed of the drive shaft after the internal gear shift is provided, and these outputs are input to the control device 31.

The control device 31 detects the pressure-sensitive switches 27 and 28 during vehicle speed control for controlling the electric motor 23 and manual shift operation so that the engine load reaches the target load as described above. An assist control for controlling the electric motor 23 is performed so that an assist force is generated in the forward and reverse directions along the artificial operation direction of the shift lever 26 based on the information. Usually, the assist control is replaced with the vehicle speed control. The control is executed with priority. In other words, even when the vehicle speed control is being executed, the pressure-sensitive switches 27 and 2 are set based on the manual operation.
When any one of the operations 8 is operated, the assist control is executed with priority based on the operation, so that safety in traveling is ensured.

The control device 31 determines whether the shift lever interferes with an external object during the execution of the vehicle speed control based on the detection information of the pressure-sensitive switches 27 and 28 and the detection information of the potentiometer 41. No, and determining the interfering operation position, and determining that there is interference, the electric power based on the vehicle speed control at the interfering operation position regardless of the detection information of the pressure-sensitive switch. The operation of the motor 23 is continuously executed. For example, it is conceivable that the dustproof rubber GM is locally rolled up in the middle of the operation of the shift lever 26, thereby hindering the operation of the shift lever 26. In such a case, If the shift of the shift lever 26 is hindered by the dustproof rubber GM during the shift operation based on the vehicle speed control, the pressure-sensitive switch corresponding to the direction opposite to the shift direction is turned ON. Sometimes. As a result, the assist control is executed with priority, and the electric motor 23 is operated in the reverse direction. However, when the pressure-sensitive switch is operated to a position where the interference state with the dust-proof rubber GM is eliminated, the pressure-sensitive switch is in a non-detection state. The assist control is executed due to the interference with the above, and thereafter, such a state is repeated, and the hunting phenomenon occurs. Therefore, in such a case, smooth operation can be continued by continuing the vehicle speed control.

Next, the control operation of the control device 31 will be described with reference to the control flowcharts of FIGS.
When the vehicle speed auto switch is turned ON in a state where neither of the pressure-sensitive switches 27 and 28 is ON, the mode is shifted to the vehicle speed control mode (steps 1, 2, 3). In the vehicle speed control mode, when the conditions for executing the vehicle speed control are satisfied, the subsequent vehicle speed control is executed (step 13). As the above conditions, for example, the stock switch 47 and the threshing switch 49 are both ON, the engine speed is equal to or higher than the set speed, and the vehicle speed is equal to or higher than the set value. Is a condition.

When the vehicle speed control is executed, an engine speed (X) is detected, and a deviation between the engine speed and a preset no-load speed (ST) is obtained as an engine load at that time. If the value obtained by subtracting the preset target load from the load (ST-X) is within the dead zone, the speed change operation is not performed, and if the value is larger on the "positive" side, the speed is automatically reduced to fall within the dead zone. The operation is performed,
If it is larger on the "negative" side, the speed increasing operation is automatically executed so as to fall within the dead zone (steps 14 to 26).

When the pressure-sensitive switch for commanding in the direction opposite to the speed change operation based on the vehicle speed control is turned on while such vehicle speed control is being executed, the detection value of the potentiometer 41 at that time (operation Is stored in the memory (steps 1, 4, 5, 6). If the detected value is substantially the same as the previously stored value (specifically, if the detected value is within ± 2 points / 256 points with respect to the previously stored value), then at that position, For example, it is determined that the dust-proof rubber GM is raised or that the transmission lever 26 interferes with other hydraulic piping, electric wiring, or the like (steps 7 and 8). At this time, the operator is informed of this by an abnormality display lamp (not shown) or the like provided in the control unit (step 9).

After the interference determination is performed in this manner, even if the pressure-sensitive switch is turned ON, the control does not shift to the assist control until the pressure exceeds the set area including the interfering portion. The vehicle speed control is executed with priority (steps 5 and 10).

If the above-described interference determination has already been performed while the vehicle speed control is being executed (step 17), the position on the upper side of the operation direction with respect to the interference position is determined. Within the set area from the point of the interference position to the interference position (specifically, 15 points / 25
In the region from the near side of six points to the interference position), the duty ratio of the pulse signal output from the control device 31 to the transistor 37 is smaller than the small duty ratio set in the normal vehicle speed control. Then, a pulse signal is output so as to provide a large operation force by setting a large value corresponding to a pulse width that is two to three times the small duty ratio (steps 18 to 21 and steps 23 to 27). In this way, even when another object is interfering with the shift lever 26, the lever is forcibly operated in response to the interference state, and a smooth operation is performed without hunting or the like. It can be executed continuously.

One of the pressure-sensitive switches 27 and 28 is turned on
Then, the vehicle speed control is not executed, and even if it is executed, if the operation position exceeds the set area, the assist control is executed (step 11).

Next, the assist control will be described. When the shift lever 26 is artificially operated to the normal rotation side (or the clockwise reverse rotation side) which is counterclockwise in FIG.
The pin 25b comes into contact with the forward rotation-side pressure-sensitive switch 27 (or the reverse rotation-side pressure-sensitive switch 28) (steps 28 and 2).
9), a signal is input to the control device 31 from the pressure-sensitive switch 27 on the forward rotation side (or the pressure-sensitive switch 28 on the reverse rotation side). Forward-side pressure-sensitive switch 27 (or reverse-side pressure-sensitive switch 2)
8) is a set time (e.g., 200 msec) after the reverse operation of the transmission lever 26 (or after the forward operation).
(Milliseconds)) or more, and the shift lever 26 is not at the forward upper limit position (or the reverse upper limit position) (step 3).
0, 31, steps 45 and 46), and a pulse signal P on the normal rotation side (or reverse rotation side) as shown in FIG.
1 is output, and the operation current A1 on the normal rotation side (or reverse rotation side) corresponding to the pulse signal P1 is output to the electric motor 23 to perform high-speed normal rotation (or high-speed reverse rotation) (steps S32 and S4).
7) The electric motor 23 applies an assist force along the forward rotation side (or the reverse rotation side) to the transmission lever 26.

That is, in the forward area F, the transmission lever 26
Is operated to the forward rotation side, an assist force is applied to the forward rotation side from the electric motor 23, and the continuously variable transmission 3 is shifted to the speed increasing side. When the shift lever 26 is operated to the reverse rotation side, An assist force is applied from the electric motor 23 to the reverse rotation side, and the continuously variable transmission 3 is shifted to the reduction side. Conversely, when the shift lever 26 is operated in the reverse direction in the reverse region R, the assisting force is applied from the electric motor 23 to the reverse direction, and the continuously variable transmission 3 is shifted to the speed increasing side. When the motor 26 is operated to the forward rotation side, an assist force is applied from the electric motor 23 to the forward rotation side, and the continuously variable transmission 3 is shifted to the deceleration side. In this case, as shown in FIG. 13, the duty ratio of the drive pulse signal (P1) is set to “1.0”, so that the electric motor 23 is continuously driven. .

The time point of detection by the forward rotation-side pressure-sensitive switch 27 (or the reverse rotation-side pressure-sensitive switch 28) is determined by the speed change lever 26.
Set time after reverse operation (after normal operation)
c) (Step 30, Step 4)
5). In this case, when the potentiometer 41 detects a neutral state or a state close to neutral (i.e., the shift lever 26 is positioned in the excessively active region Na in the neutral region N) (steps 33 and 48), the normal rotation is performed. The electric motor 23 rotates forward (or reverses slowly) until the detection of the operation of the shift lever 26 by the pressure-sensitive switch 27 on the side (or the pressure-sensitive switch 28 on the reverse side) is no longer detected (step 34,
35, 36, steps 49, 50, 51). As a result, the hunting operation of the transmission lever 26 is suppressed.

Next, when the operation of the shift lever 26 is stopped, the signals of the pressure-sensitive switches 27 and 28 on the normal rotation side and the reverse rotation side are stopped. In this case, in the high speed range F1 of the forward area F,
When the operation of the speed change lever 26 is stopped, the control device 31 outputs a forward side (forward rotation side) pulse signal P2 ′ as shown in FIG.
Is output. In this pulse signal P2 ', the ratio (T') between the output time T 'in one cycle T and the stop time T "
/ T ″) is set to a sufficiently small value, so that the holding current A2 ′ (the aforementioned operation current A
1 is output to the electric motor 23 (steps 37, 38, 39). Similarly, when the shift lever 26 is at the forward upper limit position, the holding current A2 '
Is output to the electric motor 23 (steps S31 and S31).
39).

When the operation of the shift lever 26 is stopped in the low speed range F2 of the forward movement region F, the control device 31 sends the signal to the control unit 31 shown in FIG.
The pulse signal P2 ″ on the forward side (forward rotation side) as shown in FIG. In the pulse signal P2 ″, since the ratio T ′ / T ″ is set to a value smaller than T ′ / T ″ in P2 ′, the predetermined value B ″ on the forward rotation side is maintained. The current A2 '' (smaller than the holding current A2 'described above) is output to the electric motor 23 (Step S40).

When the operation of the shift lever 26 is stopped in the reverse region R, the control device 31 outputs a pulse signal P2 ″ on the reverse rotation side as shown in FIG.
2 ″ is output to the electric motor 23 (step S4).
1). Similarly, when the shift lever 26 is at the reverse upper limit position, the holding current A2 ″ is output to the electric motor 23 (steps S46 and S41).

The belt type continuously variable transmission 3 shown in FIG.
Since it is going to return to the neutral stop region N side due to the tension of the transmission belt 13, the small assist force on the forward rotation side (or the reverse rotation side) of the electric motor 23 in steps S 15, S 16, S 17 and the The transmission lever 26 and the continuously variable transmission 3 are held at their operation positions (transmission positions) in balance with the return biasing force to the neutral stop region N described above. In this case, when the forward current (or reverse rotation) holding current A2 of any value is supplied to the electric motor 23, the speed change lever 2
6 and the continuously variable transmission 3 are held in advance by experiments or the like, and the holding currents A2 ', A2''
Corresponds to a preset value. The holding current is fed back and detected as a voltage across the reference resistor 38, and is maintained at a set value.
The ratio (T ′ / T ″) between the output time T ′ and the stop time T ″ in the pulse signals P2 ′ and P2 ″ is determined by the controller 31.
Is automatically changed.

The shift lever 26 is operated in the neutral stop region N, and a predetermined time (for example, 200
msec) (step S42), the supply system of the operating current A1 (holding current A2) to the electric motor 23 is set to a cut-off state, and the electric motor 23 enters an idling state (step S43). The idling state of the electric motor 23 is as follows.
First electromagnetic relay 32 and second electromagnetic relay 33 shown in FIG.
Is set by exciting any one of the above and not outputting the pulse signals P1, P2 ', P2''to the transistor 37. In general, the belt continuously variable transmission has a large neutral region N, and it takes a little time from when the speed is increased to when the vehicle starts moving, but by idling the electric motor 23 as described above,
The driver can be given an impression of starting smoothly.

If the speed change lever 26 is operated in the neutral stop region N and the speed increase operation is not performed within the set time in the start region Nb (step S42), the operation current A1 to the electric motor 23 is supplied.
The supply system of (holding currents A2 ′, A2 ″) is set in a short-circuited state (step S44). In this case, the first electromagnetic relay 32 and the second electromagnetic relay 33 shown in FIG. 7 are turned off, the terminals 23a and 23b of the electric motor 23 are grounded, and the state is short-circuited.

[Other Embodiments] (1) In the above embodiment, when the pressure-sensitive switch in the opposite direction is turned on at the same position twice during execution of the vehicle speed control, it is determined that the vehicle is in an interference state with another object. However, a configuration may be adopted in which, when detection is performed at the same position three or more times, interference is detected.

(2) In the above embodiment, the interference is determined based on whether the detected value of the potentiometer is the same as the previous value. However, instead of such a configuration,
For example, if the potentiometer detects that the vehicle is in the area operated by the vehicle speed control and the reverse pressure-sensitive switch is turned on during the execution of the vehicle speed control, the pressure-sensitive switch is switched within the set time after the shift to the assist control. Switch is off
The configuration may be such that, when the state of performing the operation continues for a set number of times or more, it is determined that interference occurs.

(3) In the above-described embodiment, when the interference is determined, the electric motor is operated with the operation force larger than the normal operation force in the set area. However, the same operation force as the normal operation force is used. It may be configured to operate with.

(4) In the above embodiment, the electric motor is used as the actuator, but a hydraulic motor or another actuator may be used.

(5) In the above embodiment, a belt-type continuously variable transmission is shown as the continuously variable transmission. However, various types of continuously variable transmissions such as a hydrostatic continuously variable transmission and a tapered cone type frictionless continuously variable transmission are used. A step transmission may be used. Further, the working vehicle is not limited to the combine, and can be applied to various working vehicles such as a rice transplanter and a tractor.

[Brief description of the drawings]

FIG. 1 is a side view of a speed change operation unit.

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

FIG. 3 is a side view of a cam member.

FIG. 4 is a transmission system diagram of the combine

FIG. 5 is a plan view showing a lever guide.

FIG. 6 is a sectional view of a lever guide.

FIG. 7 is a control block diagram.

FIG. 8 is a flowchart of a control operation.

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 diagram showing a current state to the electric motor.

DESCRIPTION OF REFERENCE NUMERALS 3 Continuously variable transmission 20 Transmission section 23 Actuator 26 Transmission operation tool 27, 28 Operation detecting means 31 Control means 41 Position detecting means

Claims (4)

[Claims] An actuator operable to change the speed of a transmission portion of a continuously variable transmission for traveling, control means for controlling the actuator, and mechanically operatively connected to the speed change portion so as to be manually operable in forward and reverse directions. An operation detecting unit that detects whether or not the speed change operation tool is artificially operated, and an operation direction thereof; and the control unit sets the engine load detected by the load detecting unit to a target load. And an assist for controlling the actuator such that an assist force is generated in a forward or reverse direction along the operation direction of the speed change operation tool based on the detection information of the operation detection means. And control is performed, and
A shift operation structure of a work vehicle configured to execute the assist control prior to the vehicle speed control, wherein a position detection unit that detects an operation position of the shift operation tool is provided. Based on the detection information of the operation detection means and the detection information of the position detection means, whether or not the shift operation tool interferes with an external object during execution of the vehicle speed control and the operation detection means makes an erroneous detection. When a determination is made that an erroneous detection has been made, the operation of the actuator based on the vehicle speed control is continuously performed regardless of the detection information of the operation detection means. Speed change operation structure. 2. The control means, when executing the vehicle speed control, causes the operation detecting means to manually operate the shift operation tool in a direction opposite to an operation direction by an operation of the actuator based on the vehicle speed control. When the detected value is detected, the detected value of the position detecting means at that time is configured to be stored, and the stored value of the position detecting means is the same as or substantially the same as the previously stored value. 2. The shift operation structure for a work vehicle according to claim 1, wherein the shift operation tool is configured to determine that the shift operation tool interferes with an external object and that the operation detection unit has erroneously detected. 3. When the control means determines that the speed change operation tool interferes with an external object and the operation detection means erroneously detects the shift operation tool, the control means is located closer to the operating direction than the interfering operation position. The shift operation structure for a working vehicle according to claim 1, wherein the vehicle speed control is executed prior to the assist control until the vehicle exceeds the operation position. 4. When the control means determines that the speed change operation tool interferes with an external object and the operation detection means incorrectly detects the operation, the control means operates the actuator based on the vehicle speed control. 4. The operation according to claim 3, wherein the operation signal is output to increase the operation force by the actuator until the operation position is shifted from a position farther in the operation direction than the interfering operation position to the operation position. Gear shifting operation structure.