JPH1038064A - Travelling shift structure of working car - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent quick starting of a working car even in a case when an operator is not aware that a travelling transmission is in a transmission state and carries out operation to make a travelling device work as a load against an engine. SOLUTION: A change-over driving means MS to change a travelling transmission TM from a transmission state to transmit driving force of an engine to a travelling device over to a neutral state not to transmit driving force and a change-over control means to give a change-over indication to the change-over driving means MS when the engine reaches a set rotating state at first after the engine starts as well as a noload state detection means detects a noload state are provided in travelling speed change structure of a working car free to start the engine at the time of the noload state in accordance with detection information of the noload state detection means to detect that a load applied on the engine is in the noload state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a non-load state detecting means for detecting that a load applied to an engine is in a no-load state, and the non-load state detecting means based on detection information of the no-load state detecting means. The present invention relates to a traveling speed change structure of a working vehicle that enables the engine to be started in a state.

[0002]

2. Description of the Related Art A traveling speed change structure of a working vehicle according to the present invention enables the engine to be started when the load on the engine is not loaded, thereby reducing the power required for starting the engine and starting the engine. It is provided in a work vehicle that has improved the performance. In a structure in which this no-load state is achieved by a mechanism other than the traveling transmission such as a traveling clutch, for example, the shifting state of the traveling transmission transmits the driving force of the engine to the traveling apparatus such as wheels and crawlers. The engine can be started even in the transmission state. Therefore, when the operation of starting the engine and causing the traveling device to act on the engine as a load, that is, the operation of transmitting the driving force of the engine to the traveling device is performed while keeping the shift state of the traveling transmission, the traveling transmission Conventionally, since the work vehicle will suddenly start in response to the shift state of the vehicle, before the operator performs the operation of transmitting the driving force of the engine to the traveling device, the traveling transmission device is moved to the traveling device. Had to perform an operation to shift to a neutral state where the driving force of the engine was not transmitted.

[0003]

However, there are cases where the operator performs an operation of transmitting the driving force of the engine to the traveling device without noticing that the transmission state of the traveling transmission is in the transmission state. In such a case, in the above-described conventional configuration, the work vehicle suddenly starts and gives an uncomfortable feeling to the operator. The present invention has been made in view of the above circumstances, and an object of the present invention is to allow an operator to operate a traveling device as a load on an engine without noticing that the traveling transmission is in the transmission state. Even when the operation is performed, the work vehicle is prevented from suddenly starting.

[0004]

According to the first aspect of the present invention, the no-load state detecting means detects that the no-load state is present, and is provided after the engine is started in the no-load state. When the engine first reaches the set rotation state, the switching drive means switches the traveling transmission from the transmission state to the neutral state by the control operation of the switching control means. Therefore, even if the operator performs an operation of causing the traveling device to act as a load on the engine, that is, an operation of transmitting the driving force of the engine to the traveling device without noticing that the traveling transmission is in the transmission state, The vehicle can be prevented from suddenly starting as much as possible, and it is possible to prevent the operator from feeling uncomfortable. In addition, the switching of the traveling transmission from the transmission state to the neutral state is performed when the engine reaches the set rotation state. Therefore, for example, the operation of the switching drive means can be directly used by the engine or the switching drive means can be used. The operation of the switching means, such as supplementing the power required for the operation with the power generated by the power of the engine,
Can contribute the power of the engine in some way,
The switching drive means can be operated accurately.

[0005] Further, by providing the configuration of the second aspect, since the traveling transmission is a continuously variable transmission, it is possible to finely set the traveling speed, and
Since the shift operation in the continuously variable transmission is generally a monotonous operation, the operation mode of the switching drive unit for switching the traveling transmission from the transmission state to the neutral state can be simplified, and the configuration of the switching drive unit can be simplified. Simplification can be achieved.

[0006] Further, by providing the structure of the third aspect, the operator operates the continuously variable transmission with a manually operated speed change gear.
In the case of an artificial operation of the speed change operation tool by the operator, the operation state detecting means detects the operation direction of the operation and whether or not the operation is artificially performed, and based on the detection information, the operation tool drive means The driving operation of the speed change operation tool is performed in the operation direction of the artificial operation. That is, the driving force of the operating tool driving means assists the shifting operation of the shifting operation tool by the operator, so that the operator can perform the shifting operation with a light operating force. Moreover, the switching drive means for switching the traveling transmission from the transmission state to the neutral state is constituted by using the operation tool driving means provided for reducing the operating force, and the operation tool driving means is used to change the speed of the transmission gear. By moving the vehicle to the neutral state, it is possible to prevent the work vehicle from starting suddenly while simplifying the configuration.

In addition, with the configuration according to the fourth aspect, the operating tool driving means functions as switching driving means for switching the traveling transmission from the transmission state to the neutral state,
When the operation state detecting means detects an artificial shifting operation of the speed change operation tool toward the speed increasing side while the shift operation tool is being driven to the neutral state, the drive operation to the neutral state by the operation tool drive means is performed. To stop. That is, when the shift operation device is artificially shifted to the speed increasing side, the operator operates with the intention of increasing the speed of the work vehicle, so that the behavior of the work vehicle may give an uncomfortable feeling to the operator. Therefore, it is possible to promptly perform the operation according to the operation intention of the operator. Also, by providing the configuration according to claim 5,
The no-load state of the engine, which is a condition for starting the engine, is a state in which the driving force of the engine is not transmitted to any of the traveling device and the working device, and the engine is loaded with the engine load reduced as much as possible. As a starting thing,
The power required for starting the engine can be reduced and the startability of the engine can be improved.

[0008]

FIG. 4 shows a power transmission system of a self-removing type combine which is an example of a working vehicle. Power from an engine 1 is transmitted to a threshing device 46 via a belt tension type threshing clutch 45. At the same time, the power is transmitted to the input pulley 4 of the belt-type continuously variable transmission 3 which is the traveling transmission TM through the belt transmission mechanism 2 having the tension clutch 2a, and the power from the continuously variable transmission 3 is transmitted to the transmission. It is transmitted to the left and right crawler traveling devices 6 via a hydraulic clutch type forward / reverse switching device (not shown) of the case 5 and a traveling gear transmission (not shown). 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 cutting unit 8 is provided with a stock sensor 47 for detecting a grain stem that is cut and conveyed.

As shown in FIG. 6, the threshing clutch switch 4 which is turned off (open) when the clutch is connected to the operation lever 48 for the on / off operation of the threshing clutch 45.
The engine 1 is provided with an electromagnetic pickup type rotation speed sensor 50 for detecting the rotation speed of the engine 1. Since the rotation speed of the engine 1 decreases as the load increases, the rotation speed sensor 50 is used for detecting the load of the engine 1.

Next, the continuously variable transmission 3 and its shift operation structure will be described. As shown in FIG. 2, a first split pulley 11 is attached to an input shaft 9 to which the input pulley 4 is fixed.
A second split pulley 12 is provided on the output shaft 10, 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 include a pulley portion 14 fixed to the input shaft 9 and the output shaft 10 by a spline structure, and a pulley portion 1 movable in the axial direction.
The pulley portion 15 on the moving side of the second split pulley 12 is fixed by a spring 16 to the pulley portion 1 on the fixed side.
A cam mechanism 17 is provided which is urged to the side 4 and pushes the movable side pulley portion 15 against the fixed side pulley portion 14 in proportion to an increase in the load on the output shaft 10 side.

A ring member 18 is externally fitted to the pulley portion 15 on the moving side of the first split pulley 11 via a bearing, and a pair of pins 18a fixed to the ring member 18 are recessed on the case side of the continuously variable transmission 3. 19, 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. Is the cam member 20
The roller 18b of the pin 18a of the ring member 18 has entered the pair of concave portions 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 in the drawing from the fixed pulley portion 14 and the second split pulley 12
The pulley portion 15 on the moving side is the pulley portion 1 on the fixed side.
This is the state of the lowest speed position closest to No. 4. When the cam member 20 is rotated right and left from this state, the inclined surface 20
b, the pulley portion 15 on the moving side of the ring member 18 and the first split pulley 11 is connected to the pulley portion 14 on the fixed side.
The pulling operation approaches the side, and the winding radius of the transmission belt 13 around the first split pulley 11 increases. Along with this, the pulley portion 15 on the moving side of the second pulley 12
However, the continuously variable transmission 3 is shifted to the high speed side from the fixed pulley portion 14 to the right in the drawing.

Next, the operation structure of the continuously variable transmission 3 and the forward / reverse switching device will be described. As shown in FIGS. 2 and 1, a boss member 21 is fixed to the end of the cam member 20 outside the continuously variable transmission 3, and the sector gear 2 is fixed to the boss member 21.
2 is fixed. An electric motor 23 is fixed to a fixed portion of the body, and a speed reduction mechanism 24 using a spur gear is
And the pinion gear 24a of the speed reduction mechanism 24
Are engaged with the sector gear 22. A ring member 25 is externally fitted to the boss member 21, and a transmission lever 26 (corresponding to a transmission operation tool) is supported by the ring member 25.

The shift lever 26 is swingable in the cross direction, and as shown in FIG. 5, forms a guide groove 44a for forward shift of the lever guide, a guide groove 44c for reverse shift, and a stepped portion for operating state switching. Intermediate guide groove 44b
Rocking operation along each of the guide grooves 4
4a or the reverse shift guide groove 44c, when operated along the deceleration side operation direction, the forward shift guide groove 4c
4a. At the inner edge k of the reverse transmission guide groove 44c, the shift lever 26 is forcibly received and restricted at a position corresponding to the traveling neutral state, so that the traveling state is not switched to the forward / backward traveling state due to excessive operation. Have been.

The pin 25 of the arm 25a of the ring member 25
b enters the opening 22a of the sector gear 22, and a pair of rubber-like pressure sensors 27 and 28 are fixed to the sector gear 22 so as to sandwich the pin 25b of the arm 25a. A switching valve (not shown) for switching the forward / reverse switching device between the forward position, the reverse position, and the neutral stop position is provided, and the sector gear 22 and the switching valve are connected to a push-pull wire 29.
And the accommodation mechanism 30 is linked.

A potentiometer 41 is mounted on a fixed wall 43 on the continuously variable transmission 3 side, and a lateral pin 42a at the tip end of a swing lever 42 extending from the potentiometer 41 is inserted into a long hole 22b formed in the sector gear 22.
, So that the shift state of the continuously variable transmission 3 can be detected.

As shown in FIG. 6, 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 that determine the direction of the current supplied to the third motor 3 are driven by excitation by the transistors 35 and 36, and the power supplied to the electric motor 23 is controlled by a pulse signal from the controller 31 as described later. P1, P2 ', P2 "and the like are controlled by a transistor 37. In addition, a reference resistor 38 and a reference resistor 38 for detecting a value of a holding current A2 supplied to the electric motor 23 described later. Is provided with a smoothing circuit 39 for smoothing the voltage between both ends of the motor 1. Accordingly, the electric motor 23 functions as operating tool driving means for driving and operating the shift lever 26.

In the present combiner, as shown in FIG. 6, in addition to the pressure-sensitive sensors 27 and 28, an upper-limit vehicle speed setting device 51 for setting the upper-limit vehicle speed in three stages, and the vehicle speed control is switched between automatic and manual. Speed auto switch 52 for
Signals from the vehicle speed sensor 53 and a pedal operation detection switch 56 for detecting that the brake pedal 55 has been depressed are input to the control device 31 and used for controlling the continuously variable transmission 3. Although the detailed description is omitted, in a state where the brake pedal 55 is depressed, the tension clutch 2a of the belt transmission mechanism 2 is in a disengaged state, and the engine provided on the left and right crawler traveling devices 6 is provided separately. The left and right steering clutches for turning on / off the power transmission from the first and second power transmissions are simultaneously turned off, and the left and right crawler traveling devices 6 are braked. As shown in FIG. 7, the pedal operation detection switch 56 is disposed in the middle of the wiring between the main switch 57 and the control terminal CT of the starter 54 together with the threshing clutch switch 49, and
Is involved as a starting condition. For this reason, both the threshing clutch switch 49 and the pedal operation detecting switch 56 have two independent open / close terminals. In FIG. 7, the battery terminal V among the terminals of the main switch 57 is shown.
2 schematically shows T and a starter terminal ST.

In FIG. 7, when the main switch 57 is rotated to the "start" position, the battery terminal VT and the starter terminal ST of the main switch 57 are connected. At this time, the threshing clutch switch 49 is turned "OFF". (When the threshing clutch 45 is in the connected state) or when the pedal operation detection switch 56 is "OFF" (when the brake pedal 5
5 is not depressed), the starter 54 does not operate, and when the threshing clutch switch 49 and the pedal operation detection switch 56 are "ON",
Power is supplied from the battery 58 to the control terminal CT of the starter 54 via the main switch 57, and as a result, the battery 5 is connected between the battery terminal BT of the starter 54 and the ground terminal GT.
The electric current from 8 flows, the starter 54 operates, and the engine 1 starts. After the engine 1 is started, the battery 58 is charged with electric power generated by a dynamo or the like (not shown).

Therefore, the state in which the driving force of the engine 1 is not transmitted to the threshing device 46 as the working device and the driving force of the engine 1 is not transmitted to the left and right crawler traveling devices 6 as the traveling devices is referred to as the engine 1 The engine 1 is started in the no-load state, and the threshing clutch switch 49
The pedal operation detection switch 56 functions as no-load state detection means NL for detecting that the load applied to the engine 1 is in a no-load state, and as shown in FIG. 7, the threshing clutch switch 49 and the pedal operation detection switch 5
6 is connected in series between the starter terminal ST of the main switch 57 and the control terminal CT of the starter 54, thereby constituting a restraining means EK for restraining the start of the engine 1.

Next, the control operation of the control device 31 when the engine 1 is started as described above will be described with reference to the flowchart of FIG. The process at the time of starting the engine 1 is started as the main switch 57 is rotated to the entry side. Threshing clutch switch 4
9 and the pedal operation detection switch 56 are “ON”, that is, the brake pedal 5
When step 5 is operated (steps S50 and S51)
Detects the operating position of the shift lever 26 with the potentiometer 41, and terminates this processing if the shift lever 26 is in the neutral stop region N shown in FIG. (Step S52), wait until the engine speed detected by the speed sensor 50 reaches the set rotation state (for example, 500 RPM or more) (step S53), and then operate the electric motor 23 to set the speed change lever 2
6 to the neutral stop area N (step S5).
4). When the shift lever 26 moves to the neutral stop region N (Step S55), the electric motor 23 is stopped (Step S57). However, the shift lever 26 moves to the speed increasing side until the shift lever 26 reaches the neutral stop region N. When the pressure sensor 27 detects that the operation has been performed manually (step S
56) The electric motor 23 is stopped (step S5).
7) Stop moving operation to the neutral stop area N. Therefore, the electric motor 23 also functions as a switching drive means MS for switching and driving the traveling transmission device TM from the transmission state to the neutral state, and the control device 31 serves as a switching control means CC for issuing a switching instruction to the switching drive means MS. Function.

Next, control of the continuously variable transmission 3 by the control device 31 will be described. The control of the continuously variable transmission 3 includes an automatic speed change control mode and a manual speed change mode. In the automatic transmission control mode, the control device 31 controls the rotation speed sensor 50
, The transmission 3 is automatically shifted to maintain the load of the engine 1 at the target load. To explain, the stock sensor 47 is ON and the threshing clutch switch 49 is OFF, and the vehicle speed is 0.1
The engine speed X in the case where the control condition of m / sec is satisfied is stored in advance as the reference speed ST in the no-load state of the engine. Then, the engine load ST-X defined by the down amount of the engine speed X from the reference speed ST is equal to a preset target load (target down amount).
The speed change electric motor 23 is intermittently operated on the speed increasing side or the decelerating side while changing the duty ratio of the drive pulse signal for the transistor 37 so as to maintain the speed. However, when the shift lever 26 is operated by the operator during the operation in the automatic shift control mode, the manual operation is prioritized.

Hereinafter, the operation of the control device 31 in the automatic transmission control mode will be described with reference to the flowchart shown in FIG. When the pressure-sensitive sensors 27 and 28 are OFF (step S101), the starting condition of the control operation is checked. That is, it is checked whether or not the control condition that the threshing clutch switch 49 is OFF and the stock sensor 47 is ON and the vehicle speed is 0.1 m / sec or more is satisfied, and if the control condition is satisfied (step S102), The state of the vehicle speed auto switch 52 is checked (step S103). If the vehicle speed auto switch 52 is ON, the vehicle speed control mode is set. In this case, the engine speed X is detected (step S104), and the engine load ST-X, which is the difference from the reference speed ST, is set as the target load. It is checked whether or not (step S105).

If it is larger than the target load, the duty ratio is set in accordance with the deviation, and a pulse signal having the set duty ratio is output to the transistor 37 to perform a deceleration operation (steps S106 and S107). If the vehicle speed detected by the vehicle speed sensor 53 is lower than the upper limit vehicle speed set by the upper limit vehicle speed setting device 51, the duty ratio is set according to a deviation from the target vehicle speed, and the duty ratio is set. A pulse signal having a duty ratio is output to the transistor 37 to perform a speed-up operation (steps S108, S109, S110). If the vehicle speed is equal to or higher than the upper limit vehicle speed, the shift operation is stopped (step S1).
08, S111). If the load is within the dead zone for the target load, the gear shift operation is stopped (step S1).
11). If the vehicle speed auto switch 52 is in the OFF state or if the pressure-sensitive sensors 27 and 28 are in the ON state, the vehicle enters the manual shift mode (step S200).

Next, in the manual shift mode (step S20)
The operation of the continuously variable transmission 3 and the forward / reverse switching device by the shift lever 26 in 0) will be described with reference to the flowcharts of FIGS. When the shift lever 26 is operated from one end of the neutral stop region N to the forward side range, the forward / reverse switching device is operated to the forward position by the push-pull wire 29 and the switching valve.
Is operated from the neutral stop position N to the reverse range,
The forward / reverse switching device is operated to the reverse position by the push-pull wire 29 and the switching valve.

[1] When the shift lever 26 is started to be operated in the normal rotation direction (or the reverse rotation direction) which is counterclockwise in FIG. 1, the pin 25b is moved to the normal rotation side pressure sensor 27 (or in the reverse rotation direction). Pressure sensor 28) (step S4,
S5) A signal is input to the control device 31 from the forward-side pressure sensor 27 (or the reverse-side pressure sensor 28).
The time point detected by the pressure sensor 27 on the forward rotation side (or the pressure sensor 28 on the reverse rotation side) is the first set time T1 (for example, 200) after the reverse operation of the shift lever 26 (or after the forward operation).
msec) (steps S6 and S21) and the shift lever 26 is not at the forward upper limit position (or the reverse upper limit position) (steps S7 and S22), the control device 31 sends the forward rotation side as shown in FIG. The pulse signal P1 on the reverse rotation side is output, and the forward rotation side (or the reverse rotation side) corresponding to the pulse signal P1 is output.
Is output to the electric motor 23 to perform high-speed normal rotation (or high-speed reverse rotation) (steps S8 and S23), and the assist force along the normal rotation side (or reverse rotation side) is applied from the electric motor 23 to the shift lever 26. Given.

In other words, when the shift lever 26 is operated in the forward rotation direction in the forward movement region F shown in FIG. 5, an assist force is applied from the electric motor 23 to the forward rotation side, and the continuously variable transmission 3 shifts to the speed increasing side. Therefore, when the shift lever 26 is operated in the reverse direction, the assisting force is applied from the electric motor 23 to the reverse direction, 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 26 is operated to the forward rotation side,
An assist force is applied to the forward rotation side from the electric motor 23,
The continuously variable transmission 3 is shifted to the reduction side. in this case,
As shown in FIG. 13, in one cycle T, the ratio between the output time T ′ of the pulse signal P1 and the cycle T is set to 1.0, so that the pulse signal P1 is continuously output. ing. In FIG. 13, “ON”, “OF”
“F” means “ON” and “OFF” of the transistor 37.

[2] In the above [1], the time point detected by the pressure sensor 27 on the forward rotation side (or the pressure sensor 28 on the reverse rotation side) is determined after the reverse rotation operation of the shift lever 26 (after the forward rotation operation).
Is within the first set time T1 (200 msec) (steps S6 and S21). In this case, when the potentiometer 41 detects a neutral state or a state near the neutral state (that is, the shift lever 26 is located in the excessively high area Na in the neutral area N shown in FIG. 5) (step S).
9, S24), the electric motor 23 is operated for the second set time T2 so that the forward rotation-side pressure sensor 27 (or the reverse rotation-side pressure sensor 28) does not detect the operation of the shift lever 26 to the speed increasing side. Slow forward (or slow reverse) (steps S10, S11, S25, S26), thereby suppressing the hunting operation of the transmission lever 26.

[3] The potentiometer 41 does not detect a neutral state or a state close to neutral (steps S9 and S2).
4) After the reverse rotation operation (or after the forward rotation operation) of the shift lever 26, the first set time T1 has elapsed (step S1).
2, S27), if the shift lever 26 is not at the forward upper limit position (reverse upper limit position) (steps S7, S22), the pulse signal P1 is output from the control device 31, and the operating current A
1 is output to the electric motor 23, and the above-described assist force is applied from the electric motor 23 to the shift lever 26.

[4] If the potentiometer 41 does not detect a neutral state or a state close to neutral, and the first set time T1 has not elapsed after the deceleration operation, the process returns to S200 in FIG. 9 (steps S12 and S27). [5] Next, when the operation of the shift lever 26 is stopped, the signals of the pressure-sensitive sensors 27 and 28 on the forward rotation side and the reverse rotation side are stopped (steps S4 and S5). In this case, when the operation of the shift lever 26 is stopped in the high-speed range F1 of the forward area F shown in FIG.
The forward side (forward rotation side) pulse signal P2 'shown in FIG. In the pulse signal P2 ', the ratio (T' /
Since T) is set to a sufficiently small value, the holding current A2 '(displayed as an average current and sufficiently smaller than the above-described operation current A1) of the predetermined value B' on the normal rotation side is electrically driven. The output is output to the motor 23 (step S15). In the above [3], also when the shift lever 26 is at the forward upper limit position (step S7), the holding current A2 'is similarly set.
Is output to the electric motor 23.

In the low speed range F2 of the forward range F shown in FIG. 5 (step S14), when the operation of the shift lever 26 is stopped, a pulse signal on the forward side (forward rotation side) as shown in FIG. P2 ". In the pulse signal P2", the ratio T '/ T is equal to the ratio P2'.
Is set to a value smaller than T ′ / T in the above, the holding current A2 ″ (shown as an average current and smaller than the above-described holding current A2 ′) of the predetermined value B ″ on the normal rotation side is Output to the electric motor 23 (step S1
6).

In the reverse region R (step S13),
When the operation of the shift lever 26 is stopped, a pulse signal P2 "on the reverse rotation side as shown in FIG. 13 is output from the control device 31, and the holding current A2" is output to the electric motor 23 (step S17). In the above [3], the holding current A2 "is similarly output to the electric motor 23 when the shift lever 26 is at the reverse upper limit position.

Since the continuously variable transmission 3 shown in FIG. 2 is about to return to the neutral stop area N due to the tension of the transmission belt 13, the forward (or reverse) rotation of the electric motor 23 in steps S15, S16 and S17. Side) and the return urging force of the continuously variable transmission 3 toward the above-mentioned neutral stop region N balances, so that the shift lever 26 and the continuously variable transmission 3 are held at their operation positions (shift positions). Is done.

In this case, when the holding current A2 on the normal rotation side (or reverse rotation side) of the value is supplied to the electric motor 23, it is determined by experiments or the like that the shift lever 26 and the continuously variable transmission 3 are held. The values of the holding currents A2 ', A2 "which have been grasped in advance are predetermined values B', B". As shown in FIG. 13, a predetermined value B ′ is obtained for the forward rotation side (or reverse rotation side) holding currents A2 ′ and A2 ″ supplied to the electric motor 23.
, B ", only the holding currents A2 ', A2" in the small range C are (the holding currents A2', A2 "out of the small range C).
Are ignored), and are detected by feedback, and the holding currents A2 'and A2 "on the normal rotation side (or the reverse rotation side) are detected.
Are maintained at the predetermined values B ', B ".
2 ', P2 ", the ratio (T' / T) of the controller 31
Is automatically changed.

If the speed change lever 26 is operated in the neutral stop region N, and it is within the third set time T3 (for example, 200 msec) after the speed increasing operation in the start region Nb shown in FIG. 5 (step S).
18), operating current A1 (holding current A
The supply system of 2) is set in a cut-off state, and the electric motor 23 enters an idling state (step S19). The idling state of the electric motor 23 is indicated by a pulse signal P
1, P2 ', P2 "are not output, and
The setting is performed by exciting one of the electromagnetic relays 32 and 33. The belt-type continuously variable transmission generally has a large neutral region N and takes a little time from the start of the speed increase operation to the start. However, by idling the electric motor 23 as described above, the operator can smoothly operate. You can give the impression of starting.

If the shift lever 26 is operated in the neutral stop region N and the speed is not increased within the third set time T3 in the start region Nb (step S18), the operation current A1 (the holding current A2) to the electric motor 23 is maintained. , A2 ") is set in a short-circuited state (step S20). Therefore, the pressure-sensitive sensors 27 and 28 determine the operation direction of the shift lever 26 and whether the shift lever 26 is artificially operated. The control device 31 functions as operation state detection means OD for detecting whether or not
Also functions as assist control means AC for operating the electric motor 23 so as to drive the shift lever 26 in the operation direction of the shift lever 26.

[Other Embodiments] Other embodiments will be listed below. In the above-described embodiment, the electric motor 23 as the operating tool driving means drives the sector gear 22 to drive the shift lever 26 as the shift operating tool interlocked with the sector gear 22. For example, the specific position at which the driving force of the operating tool driving means acts, such as directly swinging the shift lever 26, can be changed in various ways. In the above-described embodiment, the traveling transmission TM is constituted by the belt-type continuously variable transmission 3. However, various types of traveling transmissions such as a hydrostatic continuously variable transmission (so-called HST) are used. Is also good.

In the above embodiment, the traveling transmission T
Switching drive means M for switching M from the transmission state to the neutral state
S and the operating tool driving means for driving and operating the shift lever 26 are also used by the electric motor 23. However, the switching drive means MS is provided with an actuator separate from the electric motor 23, May be driven.

[Brief description of the drawings]

FIG. 1 is a side view showing the vicinity of a continuously variable transmission, a shift lever, and an electric motor according to an embodiment of the present invention.

FIG. 2 is a longitudinal rear view of the continuously variable transmission according to the embodiment of the present invention;

FIG. 3 is a plan view of a cam member for gear shifting operation in the continuously variable transmission according to the embodiment of the present invention;

FIG. 4 is a schematic diagram showing a transmission system of a combine according to the embodiment of the present invention.

FIG. 5 is a view showing a lever guide according to the embodiment of the present invention;

FIG. 6 is a diagram showing a control circuit system of the electric motor according to the embodiment of the present invention;

FIG. 7 is a schematic circuit diagram for starting an engine according to the embodiment of the present invention;

FIG. 8 is a flowchart according to the embodiment of the present invention.

FIG. 9 is a flowchart according to the embodiment of the present invention.

FIG. 10 is a flowchart according to the embodiment of the present invention;

FIG. 11 is a flowchart according to the embodiment of the present invention;

FIG. 12 is a flowchart according to the embodiment of the present invention;

FIG. 13 is an explanatory diagram of control of the electric motor according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Engine 3 Continuously variable transmission 6 Traveling device 23 Operating tool driving means 26 Shift operating tool 46 Working device AC assist control means CC switching control means MS Switching driving means NL No load state detecting means OD Operation state detecting means TM Traveling transmission

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display F16H 59:14 59:42 59:44

Claims (5)

[Claims] 1. An unloaded state detecting means for detecting that a load applied to an engine is in a no-load state, and starting of the engine in the no-load state based on information detected by the no-load state detecting means. A traveling speed change structure of a work vehicle, wherein the traveling speed change device transmits the driving force of the engine to the traveling device. Switching drive means for switching to a neutral state in which no driving force is transmitted, and the no-load state detecting means detects the no-load state, and after the engine is started, the engine is first brought into a set rotation state. And a switching control means for issuing a switching instruction to the switching driving means when the switching speed is reached. 2. The traveling transmission structure for a working vehicle according to claim 1, wherein the traveling transmission is a continuously variable transmission. 3. An operation tool driving means for driving and operating a manually operated speed change operation tool for the continuously variable transmission, an operation direction of the speed change operation tool, and whether the speed change operation tool is artificially operated. Operation state detection means for detecting a heel; and, based on the detection information of the operation state detection means, when the speed change operation tool is artificially operated, the operation tool drive means changes the operation direction of the speed change operation tool. 3. The work according to claim 2, further comprising: an assist control means for operating the operation tool driving means so as to drive and operate the speed change operation tool, and wherein the switching drive means is constituted by the operation tool driving means. Vehicle speed change structure. 4. The switching control means, wherein the operation state detecting means detects a speed change operation of the speed change operation tool to a speed increasing side while the switching drive means is driving to switch from the transmission state to the neutral state. The traveling speed change structure for a working vehicle according to claim 3, wherein the switching drive is stopped when the driving is performed. 5. The no-load state detecting means is configured to detect, as the no-load state, a state in which the driving force of the engine is not transmitted to any of the traveling device and the working device. Item 5. The traveling speed change structure of a working vehicle according to any one of Items 1 to 4.