JP2002234357A - Vehicle speed change device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that an operation is complicated and is hard to be understood since, conventionally, a lever for operating a main transmission and a lever for operating a subtransmission are separately provided. SOLUTION: In a traveling vehicle, a hydraulic type continuously variable transmission 23 having a variable displacement hydraulic pump 51 and a variable displacement hydraulic motor 52 is mounted. In this traveling vehicle, a movable swash plate 53 of the hydraulic pump and a foot operating transmission tool are connected to be interlocked with each other, and a movable swash plate 54 of the hydraulic motor and an actuator 55 are connected to be interlocked with each other. The actuator is operated through an operation of a manual shift operation tool arranged near a seat, the shift operation tool is constituted of a switch, and the shift operation tool is arranged to a subtransmission lever.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission device provided in a traveling vehicle such as a tractor or the like, which uses a variable displacement hydraulic pump and a variable displacement hydraulic motor to increase the range of vehicle speed change and facilitate the operation thereof. So on the technology.

[0002]

2. Description of the Related Art Conventionally, in a working vehicle such as a tractor,
The hydraulic continuously variable transmission (HST) is used as the main transmission,
Further, a technology in which a subtransmission device is provided to enable a speed change is known. Because the HST uses a variable displacement hydraulic pump and a constant displacement hydraulic motor, a multi-stage auxiliary transmission for increasing or decreasing the driving force after the HST is required. Each of these transmissions is provided with a shift operation tool, and the main shift is performed by connecting the swash plate of the hydraulic pump to the main shift lever and rotating the main shift lever. The auxiliary transmission is configured to be a gear selection type, in which a slider is connected to an auxiliary transmission lever, and the auxiliary transmission is operated to operate the auxiliary transmission, and each is operated separately. In addition, a technique in which a main shift operation is performed by a foot pedal is also known.

[0003]

However, since the main shift lever and the auxiliary shift lever are arranged at different positions,
Lever operation was increased to obtain the desired vehicle speed, which was complicated. In addition, since the sub-transmission is configured as a gear selection type, the sub-transmission cannot be operated until the power transmission is cut off by operating the main clutch when performing the sub-transmission operation, resulting in reduced work efficiency and reduced operability. Was getting worse.

[0004]

The present invention uses the following means in order to solve the above problems. That is, according to the present invention, in a traveling vehicle equipped with a hydraulic stepless transmission having a variable displacement hydraulic pump and a variable displacement hydraulic motor, the movable swash plate of the hydraulic pump is interlocked with the foot-operated shifting operation tool. The movable swash plate of the hydraulic motor is connected to the actuator in an interlocked manner, and the actuator is operated by operating a manual shift operation tool disposed near the seat.

According to a second aspect of the present invention, the shift operation tool is constituted by a switch, and the shift operation tool is disposed on the auxiliary speed change lever.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The problems and means to be solved by the present invention are as described above. Next, an embodiment of the present invention shown in the attached drawings will be described. FIG. 1 is a side view of a tractor equipped with a shift changing device according to the present invention, FIG. 2 is a skeleton diagram showing a drive transmission path, FIG. 3 is a control block diagram, and FIG. 4 is a side view of an arrangement portion of a shift lever.

First, a schematic configuration of a tractor, which is an embodiment of a work vehicle equipped with a shift changing device according to the present invention, will be described. In FIG. 1, an engine 2 is arranged in a hood 1 at the front of the machine, and the engine 2 is
And the dashboard 10 at the rear of the hood 1
A steering handle 17 serving as steering means protrudes upward. Behind the steering handle 17, the seat 11
In the vicinity of the seat 11, there are disposed a sub-transmission lever 12, a shift switch 59, a work implement elevating lever, and the like, which serve as a shift operation tool for changing an angle of a sub-main transmission and a movable swash plate 54 of the hydraulic motor 52, which will be described later. Have been. The dashboard 1
On the step 14 between the seat 0 and the seat 11, a foot pedal 15 is disposed as a foot-operated main speed change operation tool, and is linked to a movable swash plate 53 of a hydraulic pump 51 described later. A portion in which the sub-shift lever 12, the foot pedal 15, the seat 11, the steering handle 17 and the like are provided is a control unit 13 and is covered by the cabin 3.

Further, front wheels 8.8 are supported on both sides of the front of the machine, and rear wheels 6.6 are supported on both sides of the rear. In addition, a transmission case 5 is arranged below the seat 11,
A work implement mounting device 4 of a three-point link type for mounting various work machines is mounted behind the transmission case 5. The PTO shaft 27 protrudes from the rear surface of the transmission case 5 so that the work machine can be driven. Further, a front wheel power take-out case 7 is provided at the front lower portion of the transmission case 5, and transmits power to a front axle case via a transmission shaft 9 ahead of the front wheel power take-out case 7, and a front wheel 8 supported by the front axle case Can be driven.

Next, the drive transmission system of the tractor will be described with reference to FIG. An HST (hydraulic continuously variable transmission) 2 disposed in the transmission case 5 via a damper or clutch (not shown) at the rear of the output shaft of the engine 2.
Power is transmitted to the input shaft 33 of the third hydraulic pump 51, and the input shaft 33 extends rearward through the hydraulic pump 51 to drive the hydraulic pump 51 and to operate the PTO clutch 25 and the PTO transmission mechanism 26. Power is transmitted to the PTO shaft 27 through the PTO shaft 27.

An auxiliary transmission 24 is provided on the rear side of the HST 23, that is, on the downstream side of the power transmission path. The auxiliary transmission 24 can be shifted by a hydraulic clutch. The gears can be shifted by operating a low-speed clutch 65 or a high-speed clutch 66 by operating a switching valve 64 described later. Power is transmitted to a rear wheel differential device 34 via a drive pinion 32 provided at a rear end of the drive shaft 30 as an output shaft of the auxiliary transmission 24 as a drive shaft 30, and left and right sides of the rear wheel differential device 34. Differential yoke shaft 35L / 35
R, the rear wheels 6.6 are driven via final deceleration mechanisms 36.

A front wheel drive gear 40 is fixed on the drive shaft 30 and is transmitted from the front wheel drive gear 40 to the front wheel transmission 29 via a double counter gear 41. The front wheel transmission 29 is a hydraulic four-wheel drive clutch 3.
7 and the front wheel speed-increasing clutch 38, and both clutches are OF
In the case of F, the vehicle is driven by two wheels with only the rear wheels, and is operated during traveling on the road. When the four-wheel drive clutch 37 is turned on, the front wheels 8.8 and the rear wheels 6.6 are driven at the same speed, and are activated during work or the like. When the steering wheel 17 is rotated by a predetermined angle or more during operation, the front wheel speed increasing clutch 38
N, the driving speed of the front wheels 8.8 is increased more than that of the rear wheels 6.6 so that the driving speed is about twice as high.

The power transmitted by the front wheel transmission 29 is transmitted from the output shaft to the front differential 43 in the front axle case via the transmission shaft 9, and the differential yokes on both sides of the front differential 43. Axis 4
The front wheels 8.8 are driven via 4L / 44R and final deceleration mechanism 45.

Next, a description will be given of a shift changing device according to the present invention. The HST 23 is composed of a variable displacement hydraulic pump 51 and a variable displacement hydraulic motor 52. A movable swash plate 53 constituting the hydraulic pump 51 is a foot serving as a foot-operated main speed change operation tool shown in FIGS. The pedal (HST pedal) 15 is connected via a link or the like (not shown), and the foot pedal 15 is disposed on the operation unit 13. In the present embodiment, the forward pedal 15F and the reverse pedal 15R
Is arranged. However, the forward pedal 15F and the reverse pedal 15R are arranged side by side on the left and right. However, it is also possible to adopt a seesaw type so that the shift operation can be performed by one foot pedal 15.

When the forward pedal 15F is depressed, the output shaft 31 of the hydraulic motor 52 is normally rotated, and the movable swash plate 53 is proportional to the amount of rotation of the forward pedal 15F.
Is also rotated and tilted, and the output rotation can be increased by increasing the discharge oil amount in proportion to the tilt angle, so that a forward main shift can be performed. When the reverse pedal 15R is depressed,
The movable swash plate 53 is tilted in the opposite direction to the above, pressure oil is supplied in the opposite direction, and the output shaft 31 of the hydraulic motor 52 is rotated in the opposite direction, and is proportional to the rotation angle of the reverse pedal 15R in the same manner as described above. The output rotation is obtained, and the reverse main shift can be performed.

A movable swash plate 54 constituting the hydraulic motor 52 is connected to an actuator 55 via a link (not shown).
The movable swash plate 54 is tilted by operating the actuator 55. Although the actuator 55 is a hydraulic cylinder in the present embodiment, the actuator 55 may be constituted by a motor, a solenoid or the like, and is not limited.

The actuator 55 is connected to a switching valve 56 via a flow control throttle and a check valve for preventing backflow.
The switching valve 56 is formed of an electromagnetic valve, and the solenoids 56a and 56b of the switching valve 56 are connected to a controller 57. The controller 57 has a shift operating tool for driving the solenoids 56a and 56b. Is connected to the shift switch 59. The controller 57 is connected to a sensor 58 for detecting the operating position of the actuator 55.

Further, the shift switch 59 is disposed on the control unit 13, and in this embodiment, as shown in FIG. 4, the shift switch 59 is integrated with the auxiliary transmission lever 12 so that the shift switch 59 can be easily operated. Is provided. That is, the shift switch 5 is provided on the side of the grip 12a of the subtransmission lever 12.
9 are arranged, and are arranged on the front surface in this embodiment. However, they can be arranged on the left and right sides. The speed can be increased by rotating the shift switch 59 upward, and the speed can be reduced by rotating the shift switch 59 downward. Further, the shift operation tool is not limited to the lever switch, and can be increased or decreased by using two seesaw switches or two push button switches, or can be increased or decreased by using a dial or a knob using a volume.

The primary side of the switching valve 56 is connected to a hydraulic pump 61 via a flow divider 60, and the hydraulic pump 61 is driven by the engine 2 so that hydraulic oil in the transmission case 5 is sucked and discharged. ing. The other secondary side of the flow divider 60 is connected to an elevating mechanism 62 of the work implement mounting device 4, and the elevating mechanism 62 applies hydraulic fluid to a hydraulic cylinder in a hydraulic case mounted on the transmission case 5. And the lift arm can be rotated. 63 is a relief valve for setting the operating oil pressure of the actuator 55. A switching valve 64 is connected to a tank port of the switching valve 56, and the secondary transmission 24 is connected to a secondary side of the switching valve 64.
Connected to the low speed clutch 65 and the high speed clutch 66 of
By turning the sub transmission lever 12, the switching valve 6
4 to operate the low-speed clutch 65 or the high-speed clutch 66 to enable the sub-shift.

In the above-described configuration, at the start of traveling, first, the speed of the auxiliary transmission 24 is shifted by the auxiliary shift lever, and then the main shift is performed by depressing the foot pedal 15.
This main speed change operation is performed by the operator's foot motion so as to obtain a desired speed. When the foot pedal 15 is depressed, the movable swash plate 53 of the hydraulic pump 51 is tilted, and a predetermined amount of pressure oil is discharged from the hydraulic pump 51. Even when the vehicle is running at the desired speed set by the foot pedal 15, there are cases where the speed fluctuates due to the load or inclination of the work implement, or when it is desired to slightly increase or decrease the current speed. Then, rotate the main shift lever,
Alternatively, the power transmission is turned off by depressing the clutch pedal, and the speed is shifted by the auxiliary transmission. However, it is difficult to operate the main transmission lever delicately, and there is a limit to changing the transmission ratio greatly. In addition, shifting the speed of the sub-transmission causes the operation to be temporarily interrupted, so that a delicate change occurs in the finish, resulting in a troublesome operation.

According to the present invention, in such a case, the controller 57 is operated by operating the shift switch 59 provided in the vicinity of the auxiliary transmission lever 12 while keeping the pump capacity of the hydraulic pump 51 set by the foot pedal 15 unchanged. The solenoid 56a (or 56b) is actuated via the switch to switch the switching valve 56, pressure oil is supplied to the actuator 55, the hydraulic cylinder serving as the actuator 55 is extended (or contracted), and the hydraulic motor 52 is moved. The rotation speed of the output shaft 31 is changed by tilting the swash plate 54 so that the speed can be increased or reduced. At this time, the pump capacity is fixed, and the movable swash plate 54 of the hydraulic motor 52 is tilted. If the tilt angle is large, the motor capacity increases, the output rotation is reduced, and when working at low speed, the speed is further reduced. By doing so, work accuracy can be improved. When the tilt angle of the movable swash plate 54 is reduced, the motor capacity of the hydraulic motor 52 is reduced, the output rotation is increased, and the working efficiency can be improved.

Incidentally, the shift switch 59 is constituted by a neutral return type switch, and the speed increase (UP) or the speed reduction (DOW) is performed.
The actuator 55 is operated only when the operation is performed in N), and the operation position of the actuator 55 is detected by the sensor 58, and the operation can be performed up to the stroke limit. When the foot pedal 15 is returned to the neutral position, the actuator 55 is operated so as to be at an intermediate position between the maximum inclination and the minimum inclination of the movable swash plate 54 under the control of the controller 57. It can be increased or decreased. When the sub-shift is shifted to the high-speed position, the maximum speed is set for the vehicle, so that the shift switch 59 can be operated in a range of the maximum speed or less.

[0022]

According to the present invention, the following effects can be obtained by the configuration described above. That is, in a traveling vehicle equipped with a hydraulic stepless transmission having a variable displacement hydraulic pump and a variable displacement hydraulic motor,
The movable swash plate of the hydraulic pump is interlocked with the speed-change gear,
The movable swash plate of the hydraulic motor is linked with the actuator,
The actuator is operated by the operation of a manual shift operation tool disposed near the seat. Therefore, in addition to the main shift operation by changing the movable swash plate of the hydraulic pump with the main shift operation tool, the shift operation is performed. By operating the tool, the movable swash plate of the hydraulic motor can be tilted to change the speed continuously, and the operation range of multi-speed or stepless speed change operation can be expanded without changing the size of the transmission, and the clutch can be disengaged. Continuously variable speed is possible with simple operation without any operation. In addition, the running speed can be finely changed manually while performing the main shifting operation with the foot, so that the setting range of the running speed can be expanded and the desired shifting speed can be easily changed.

Further, when the capacity of the hydraulic pump is increased and the capacity of the hydraulic motor is increased, the output torque can be increased when working at a low speed. When the capacity of the hydraulic motor is reduced, high-speed rotation is possible. In addition, if the capacity of the hydraulic pump is reduced and the capacity of the motor is increased, low-speed output rotation is achieved, and work accuracy can be improved. As described above, by tilting the movable swash plate of the hydraulic pump and the hydraulic motor, the capacity can be reduced. It was possible to cope with various works by changing, and the work area could be expanded.

Further, since the shift operating tool is constituted by a switch and the shift operating tool is arranged on the sub-shift lever, the shift switch is operated while holding the sub-shift lever during the driving operation during work. Operability of the sub-shift operation and the shift operation can be improved.

[Brief description of the drawings]

FIG. 1 is a side view of a tractor equipped with a shift changing device of the present invention.

FIG. 2 is a skeleton diagram showing a drive transmission path.

FIG. 3 is a control block diagram.

FIG. 4 is a side view of an arrangement portion of an auxiliary transmission lever.

[Explanation of symbols]

 Reference Signs List 12 auxiliary transmission lever 15 foot pedal 23 HST (hydraulic continuously variable transmission) 51 hydraulic pump 52 hydraulic motor 53/54 movable swash plate 55 actuator 59 shift switch (shift operating tool)

Claims (2)

[Claims] In a traveling vehicle equipped with a hydraulic stepless transmission having a variable displacement hydraulic pump and a variable displacement hydraulic motor, a movable swash plate of the hydraulic pump is interlocked with a foot-operated shifting operation tool, and a hydraulic motor is provided. The movable speed swash plate is interlocked with an actuator, and the actuator is operated by operating a manual shift operation tool disposed near the seat. 2. The vehicle speed changing device according to claim 1, wherein the shift operating tool is constituted by a switch, and the shift operating tool is disposed on a sub-shift lever.