JP2000018375A - Shift operation mechanism of working vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the controllability for shift operations in a working vehicle having a plurality of clutch means transmitting drive from a prime mover to driving wheels by shifting. SOLUTION: A sensor for detecting the opening of an accelerator pedal for varying engine speed is provided, and a controller that performs shift operations by switching hydraulic clutches 22 (22a-22a) in a speed increasing direction as the opening of the accelerator pedal increases is provided. A switch capable of selection so that the sensor becomes inoperative for the controller is provided, and when the sensor 52 is inoperative, the shift operations are performed while the hydraulic clutches 22 are shifted in the speed increasing direction as the control angle of a travel shift lever increases. Pressure oil is supplied, via a servo valve 42 controlled by a controller 56, to the hydraulic clutch 22 provided for each speed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shift operation mechanism for a working vehicle provided with a plurality of clutch means for shifting a driving force from a prime mover and transmitting the driving force to driving wheels.

[0002]

2. Description of the Related Art Conventionally, a wet multi-plate clutch operated by hydraulic pressure is arranged between a transmission gear and a drive gear, that is, several hydraulic clutches are arranged on a transmission shaft, and a hydraulic pump is operated by operating a shift lever. There is known a transmission mechanism that transmits pressure oil to a hydraulic clutch at a desired speed stage through a control valve to perform a shift. In the above-described transmission mechanism, a driver manually switches a control lever interlocked with the control valve, thereby operating the clutch and performing a traveling shift.

[0003]

However, since it is not interlocked with the accelerator for controlling the output of the engine, it is necessary for the operator to operate the work vehicle in consideration of the engine output and the gear ratio by the transmission mechanism. In addition, if the gearshift operation is performed when the output of the engine is low, the engine may stop due to insufficient driving force. Further, since the shift operation can be performed by the control lever irrespective of the number of revolutions of the engine, vibrations and shocks may occur when the clutch is engaged during shifting. Further, the HST type transmission can perform continuously variable transmission by rotating the transmission lever, but the power transmission efficiency is lower than that of the hydraulic clutch type transmission. Therefore, an efficient continuously variable transmission has been desired.

[0004]

The present invention uses the following means in order to solve the above problems. First, in a working vehicle provided with a plurality of clutch means for shifting the driving force from the prime mover and transmitting it to the drive wheels, a sensor for detecting the opening degree of an accelerator for changing the rotation speed of the prime mover is provided. A shift operation mechanism for a work vehicle, comprising: a traveling shift control circuit that switches the clutch means in a speed increasing direction to perform a shift operation as the degree of opening of the accelerator increases.

According to a second aspect of the present invention, there is provided a switch capable of switching the sensor so as to be invalid with respect to the traveling speed change control circuit, and when the operation angle of the traveling speed change lever increases when the sensor is invalidated. 2. A shift operation mechanism for a working vehicle according to claim 1, wherein the shift operation is performed by switching the clutch means in a speed increasing direction.

According to a third aspect of the present invention, the clutch means is a hydraulic clutch, and pressure oil is supplied to each of the hydraulic clutches provided for each shift speed via a servo valve controlled by the traveling shift control circuit. A shift operation mechanism for a work vehicle according to claim 1, wherein:

[0007]

Embodiments of the present invention will be described with reference to the accompanying drawings. 1 is a side view of a work vehicle, FIG. 2 is a side sectional view showing a transmission case as a transmission of the work vehicle, FIG. 3 is a block diagram showing a control configuration of a hydraulic clutch, and FIG. 4 is a first embodiment of the present invention. FIG. 5 is a block diagram showing a control mechanism of the transmission according to the second embodiment of the present invention.

First, the general configuration of the tractor shown in FIG. 1 will be described. An engine E, a battery, and the like are mounted on an engine frame 1 and are covered with a bonnet 2. A steering column 3 is disposed at a rear end of the bonnet 2, and a steering wheel 4 is disposed above the steering column 3. . A front end of the flywheel clutch housing 5 is provided, a front end of which is connected to the engine E, and a rear end of which is connected to the transmission case 6. The transmission case 6 is provided with a rear wheel differential mechanism, and a rear axle 7 is extended on both left and right sides.
8 is installed. A travel power transmission mechanism from the output shaft of the engine E to the rear wheel differential mechanism is provided inside the flywheel clutch housing 5 and the transmission case 6. The rear wheel 8 can be driven by the driving force transmitted to the transmission case 6.

The front wheel 9 can be steered by turning the steering wheel 4. The steering 4
A main transmission lever 54 and an auxiliary transmission lever 30 are disposed near the seat. The traveling speed of the work vehicle is adjustable by the main transmission lever 54 and the sub transmission lever 30. In addition, a hydraulic lift device 16 and a PTO shaft 15 for mounting the working machine so as to be able to move up and down are arranged at the rear of the machine body.

Next, the power transmission mechanism will be described with reference to FIG. In FIG. 2, the flywheel housing 5 is joined to a transmission case 6, and the transmission case 6
Is joined to a rear axle case 7. A main shaft 20 connected to the flywheel in the flywheel housing 5 is disposed in the longitudinal direction of the machine from the rear of the flywheel housing 5 to the rear of the transmission case 6, and engine power is transmitted via the flywheel. I have. The rear end of the main shaft 2 is connected to a PTO shaft drive shaft 50 disposed in the rear axle case 7.
It is connected to the O clutch 151. The PTO clutch 1
51 is linked to the PTO shaft 15 via a plurality of gears and shafts, and operates the PTO clutch 151 to transmit the driving force transmitted from the main shaft 20 to the PTO shaft 51.
It is configured to be able to transmit to the shaft 15.

A partition is formed substantially vertically in the flywheel housing 5 and a clutch chamber 5a is provided behind the partition.
Is formed. In the clutch chamber 5a, a forward / reverse switching clutch 21 is disposed on the main shaft 20. By switching this, a hollow shaft 80 rotatably fitted onto the main shaft 20 from the main shaft 20 is freely rotatable. The upper gear 81 can be driven in the normal rotation direction or the reverse rotation direction.

In the transmission case 6, a main transmission chamber 6a and a sub transmission chamber 6b are formed before and after a substantially vertically formed partition wall. A drive gear train 82 is fixedly mounted on the hollow shaft 80 in the main transmission chamber 6a, and the drive gear train 82 is mounted on the drive shaft 24 disposed parallel to the main shaft 20 below the main transmission chamber 6a. The engaged driven gear train 84 is always engaged. Between the driven gear train 84 and the drive shaft 24, 1st speed, 2nd speed, 3rd speed,
Four-speed hydraulic clutches 22a, 22b, 22c and 22d are provided.

A driven gear train 84 inserted into the drive shaft 24 is configured to transmit a driving force from the hollow shaft 80 to the drive shaft 24 by the operation of the hydraulic clutch 22. The rear end of the drive shaft 24 projects into the auxiliary transmission chamber 6b of the transmission case 6, and is connected to an auxiliary transmission mechanism 86 in the auxiliary transmission chamber 6b. A high-speed gear 91 is provided on the rear end of the drive shaft 24.
A low-speed gear 92 is rotatably fitted on a second drive shaft 87 coaxial with the drive shaft 24, and a slider 93 is mounted on the second drive shaft 87 between the high-speed gear 91 and the low-speed gear 92. Are spline-fitted, and the high-speed gear 91 and the low-speed gear 92 are meshed with gears fixed on a hollow shaft 85 externally fitted on the main shaft 20, respectively.

The slider 93 is slidable in the axial direction by the rotation of the sub-transmission lever 30. When the slider 93 is engaged with the high-speed gear 91, the high-speed rotation is transmitted to the second drive shaft 87, and the slider 93 is moved to the low-speed gear 92. The low-speed rotation is transmitted from the high-speed gear 91 to the second drive shaft 87 via the gear on the hollow shaft 85 and the low-speed gear 92. Further, the second drive shaft 8 is moved from the hollow shaft 85 through a creep speed change mechanism 88.
7 can transmit the driving force of the creep speed. The rear end of the second drive shaft 87 projects into the rear axle case 7 and a small bevel gear is fixed, and the rear wheel drive gear 89 can be driven from the gear via a differential gear device. A rear wheel drive shaft 90 is inserted and fixed to the rear wheel drive gear 89 so that a driving force can be transmitted to the rear wheel 8.

Next, a control mechanism of the hydraulic clutch 22 according to the present invention will be described. 3, a hydraulic pump 43 is connected to an electromagnetic proportional valve 42 and a high-pressure relief valve 44, and a low-pressure relief valve 45 for setting a lubricating oil pressure for the clutch 22 and the like is connected to the high-pressure relief valve 44 in series. . When the pressure of the hydraulic oil supplied by the hydraulic pump 43 exceeds the set pressure of the high-pressure relief valve 44, the drain oil of the high-pressure relief valve 44 is supplied to the lubrication pump, and is adjusted by the low-pressure relief valve 45. Pressed.

The servo valve 42 is composed of an electromagnetic proportional valve. The amount of hydraulic oil passing through the servo valve 42 can be adjusted by adjusting the sliding amount of the valve body by an electromagnetic solenoid, and the pressure of the hydraulic oil can be adjusted. Is configured. The servo valve 42 has four solenoid valves 41a, 41b, 41
c and 41d are connected in parallel, and the hydraulic oil is supplied to the solenoid valves 41a, 41b, 41c and 41 via a servo valve 42.
d. The solenoid valves 41a and 41b
41c and 41d are connected to hydraulic clutches 22a, 22b, 22c and 22d corresponding to the first to fourth speeds, respectively, and by operating any of these solenoid valves to supply the corresponding hydraulic clutch 22, Hydraulic clutch 22
Are engaged to output the driving force of the gear.

An electromagnetic valve 46 is connected to the hydraulic oil discharge side of the electromagnetic valve 41 so that the hydraulic oil can be discharged to the oil tank via the electromagnetic valve 46. The solenoid valve 46
The working oil can be directly discharged from the solenoid valve 46 to the oil tank or discharged through the throttle 49 by sliding the. For this reason, by switching the solenoid valve 46 and passing the throttle 49, the discharge speed of the hydraulic oil from the hydraulic clutch 22 on the disconnection side is reduced, and the clutch 22 can be disconnected gently. .

Further, when the speed change lever is rotated to change the speed, for example, first to second speed, or second to third speed,
Or in the case of deceleration operation from 3rd gear to 4th gear or vice versa,
In the shifting process, the solenoid valves 4 on the low speed side and the high speed side
Both of the hydraulic clutches 1 and 41 are opened to supply the pressure oil. At this time, the moment when the pressure decreases to supply the pressure oil to the two hydraulic clutches 22 and 22 occurs. In order to reduce the change in the pressure oil, the opening of the servo valve 42 is electrically controlled by a traveling speed control controller 56 described later.

Next, a first embodiment of the present invention will be described with reference to FIG. In FIG. 4, an accelerator pedal 51 is connected to a throttle of the engine E via a wire or the like, and according to the amount of rotation of the accelerator pedal 51,
The rotation speed of the engine E is configured to be adjustable. An angle sensor 52 such as a potentiometer is provided at the base of the accelerator pedal 51, and detects the opening angle of the accelerator by detecting the rotation angle of the accelerator pedal 51. An angle sensor 53 such as a potentiometer is also provided at the base of the traveling speed change lever 54 so as to detect the rotation angle of the traveling speed change lever 54. The angle sensor 52 and the angle sensor 53 are connected in parallel corresponding to a changeover switch 55, and the changeover switch 55 is connected to a controller 56 mounted on a work vehicle. The first to fourth speeds (F1 to F4) of the traveling shift lever 54 are set according to the rotation angle, and the determination is made by the controller 56.

The changeover switch 55 can connect either the angle sensor 52 or the angle sensor 53 to an input section of the controller 56. When the angle sensor 52 is connected to the controller 56 by the changeover switch 55, the rotation angle of the accelerator pedal 51 is detected by the angle sensor 52, input to the controller 56, and interlocked with the depression angle of the accelerator pedal 51. When the automatic shifting operation is performed, the traveling shift lever 54
The shift can be performed without operating the. Further, by connecting the angle sensor 53 to the controller 56, the rotation angle of the traveling speed change lever 54 is detected by the angle sensor 52 and input to the controller 56, and the traveling speed change operation is performed with respect to the accelerator pedal 51. Interlocking, the speed change operation can be performed by the traveling speed change lever 54.

The controller 56 includes a driving circuit 57.5.
8.59. The drive circuit 57 includes solenoid valves 41a, 41b, 4 connected to the hydraulic clutch 22.
The solenoid valve 41 is connected to the solenoids 1c and 41d, and the supply and discharge of the hydraulic oil to and from the clutch 22 can be controlled by switching the solenoid valve 41 via the drive circuit 57. The drive circuit 58 is connected to the solenoid of the servo valve 42,
2 to control the supply amount of hydraulic oil to the hydraulic clutch 22 on the engagement side. Further, the drive circuit 59 is connected to a solenoid of the solenoid valve 46, and the solenoid valve 46 is switched so that the discharge amount of the hydraulic oil from the hydraulic clutch 22 on the disconnected side can be controlled.

In the above configuration, the controller 56 is adapted to connect the drive gear and the driven gear in the transmission case 6 corresponding to the rotation angle of the accelerator pedal 51 or the rotation angle of the traveling speed change lever 54. The electromagnetic valve 41 that engages the hydraulic clutch 22 is switched via the drive circuit 57. Further, in order to loosely engage the hydraulic clutch, the servo valve 42 is driven by the controller 56 via the drive circuit 58.
Is controlled, and the electromagnetic valve 46 is controlled via the drive circuit 59. The hydraulic valve 46 is set to a state in which the hydraulic oil is discharged to the oil tank through the throttle 49 by the electromagnetic valve 46, and the supply amount of the hydraulic oil from the hydraulic pump 43 is gradually increased by the servo valve 42, so that the hydraulic pressure on the engagement side is increased. The clutch 22 and the hydraulic clutch 22 on the disengagement side are positively engaged in a double engagement state under low pressure, and the shock during the shift transition period is reduced.

That is, in order to adopt the above configuration, the accelerator pedal 51 is depressed, and the rotation speed of the accelerator pedal 51 causes the engine speed to increase, and the servo valve 42 and the solenoid valve 41 controlled by the controller 56. A gear change operation is performed by 46. For this reason, the operator of the work vehicle does not operate the traveling speed change lever 54 and depresses the accelerator pedal 51, and the controller 56 causes the controller 56 to move the drive gear corresponding to the amount of rotation of the accelerator pedal 51 from the reference position. A driven gear is connected, and the work vehicle can be driven at an arbitrary vehicle speed. Further, the changeover switch 55 makes it possible to make the accelerator pedal 51 non-interlocked with the shift operation, and to perform the manual shift traveling by the traveling shift traveling lever 54.

Next, a second embodiment of the present invention will be described. In FIG. 5, an angle sensor 53 such as a potentiometer is provided at the base of the traveling speed change lever 54, and detects the rotation angle of the traveling speed change lever 54. A controller 56 is connected to the angle sensor 53, and recognizes the rotation angle of the traveling speed change lever 54 detected by the angle sensor 53. The controller 56 includes driving circuits 57, 58, 59, a driving circuit 63
Are connected, and the drive circuits 57, 58, 59 and the drive circuit 63 are configured to be controllable. The drive circuit 57 includes solenoid valves 41 a and 41 for operating the hydraulic clutch 22.
The solenoids b, 41c and 41d are connected.

The drive circuit 58 is connected to a solenoid of a servo valve 42 for adjusting the amount of oil supplied to the electromagnetic valve 41, and switches the servo valve 42.
The drive circuit 59 is connected to a solenoid of the solenoid valve 46 for adjusting the amount of oil discharged by the solenoid valve 41,
The switching of the solenoid valve 46 is controlled. The drive circuit 63 is connected to an electric motor 62 provided at the base of the accelerator pedal 51 via a changeover switch 64, and the accelerator pedal 51 is configured to be rotatable by operating the electric motor 62. ing.

In the above configuration, the changeover switch 64
When the drive circuit 63 and the electric motor 62 are in a connected state, the drive circuit 63 operates the electric motor 62 by a predetermined amount in accordance with the operation angle at which the traveling speed change lever 54 is turned, and the accelerator pedal 51 is automatically rotated to adjust the output of the engine. The controller 56
Stores the output rotational speed of the engine E corresponding to the traveling gear position by the traveling shift lever 54, and adjusts the output rotational speed of the engine in accordance with the shift operation by the traveling shift lever 54.

For this reason, vibrations during shifting can be reduced, and the load on the transmission mechanism in the transmission case 6 and the engine E can be reduced. Further, it is possible to easily perform a shift operation without considering the output rotation speed of the engine at the time of shifting, and there is no problem that the engine stops when the shift operation is performed when the engine output rotation speed is low. In addition, the operability of the work vehicle is improved by increasing the output of the engine when operating the traveling speed change lever 54 to the speed increasing side and decreasing the output of the engine when operating the traveling speed change lever 54 to the speed decreasing side. In addition, there is no need to stop the engine by applying too much power.

By disconnecting the connection between the motor 62 and the drive circuit 63 by the switch 64,
And the accelerator pedal 51 can be disconnected. This allows the operator to perform a shift operation at an arbitrary engine output.

[0029]

As described above, the present invention has the following advantages. First, in a working vehicle provided with a plurality of clutch means for shifting the driving force from the prime mover and transmitting the driving force to the drive wheels, a sensor for detecting the opening degree of an accelerator for changing the rotation speed of the prime mover is provided. A traveling shift control circuit for switching the clutch means in the direction of increasing speed as the opening of the accelerator increases to perform a shifting operation, so that the operator can shift the traveling vehicle without operating the traveling shift lever. It is possible to For this reason, the operability of the work vehicle can be improved, and the operator can concentrate on the ground state or the surrounding state where the work vehicle runs, thereby improving work efficiency. In addition, the traveling shift control circuit mounted on the work vehicle enables automatic shifting traveling in a rotation range where the output efficiency of the engine is high.
The durability of the engine is improved, and the load on the transmission mechanism can be reduced.

According to a second aspect of the present invention, a switch capable of ineffectively switching the sensor with respect to the traveling speed change control circuit is mounted, so that the automatic speed change and the manual speed change can be switched as required, and the automatic speed change is performed by the operator. If you don't feel like driving,
With the changeover switch, the accelerator opening and the automatic shift operation mechanism are not interlocked, and the shift operation can be performed manually, and the shift mode can be changed by the operator. As a result, the gear change operation preferred by the operator can be selected.

According to a third aspect of the present invention, the clutch means is a hydraulic clutch, and pressure oil is supplied to each hydraulic clutch provided for each shift speed via a servo valve controlled by the travel speed control circuit. In addition, the impact during shifting can be reduced, and the operability of the work vehicle can be improved. The smooth transmission operation reduces the impact applied to the transmission mechanism, thereby improving the durability of the transmission mechanism. Further, the load on the prime mover and the transmission mechanism can be reduced.

[Brief description of the drawings]

FIG. 1 is a side view of a work vehicle.

FIG. 2 is a side sectional view schematically showing a transmission of a work vehicle.

FIG. 3 is a block diagram showing a control configuration of a hydraulic clutch.

FIG. 4 is a block diagram showing a control mechanism of the transmission according to the first embodiment of the present invention.

FIG. 5 is a block diagram showing a control mechanism of a transmission according to a second embodiment of the present invention.

[Explanation of symbols]

 8 Rear wheel 9 Front wheel 22 Hydraulic clutch 41 Solenoid valve 42 Servo valve 43 Hydraulic pump 51 Accelerator pedal 52 Angle sensor-53 Angle sensor-54 Travel shift lever 55 Changeover switch 56 Controller (travel shift control circuit)

Claims (3)

[Claims] In a work vehicle provided with a plurality of clutch means for shifting the driving force from a prime mover and transmitting the same to drive wheels, a sensor for detecting an opening degree of an accelerator for changing a rotation speed of the prime mover is provided. A shift operation mechanism for a work vehicle, comprising: a traveling shift control circuit that performs a shift operation by switching the clutch means in a speed increasing direction as the opening of the vehicle increases. And a switch which can switch the sensor so as to be ineffective with respect to a traveling shift control circuit, and when the sensor is invalid, the clutch means is switched as the operating angle of the traveling shift lever increases. The shift operation mechanism for a work vehicle according to claim 1, wherein the shift operation is performed by switching to a speed increasing direction. 3. A hydraulic clutch as said clutch means,
2. The shift operation mechanism of a work vehicle according to claim 1, wherein hydraulic oil is supplied to each hydraulic clutch provided for each shift speed via a servo valve controlled by the traveling shift control circuit.