JP4667615B2 - Vehicle speed change device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a technique for widening a change range of a vehicle speed and facilitating the operation thereof using a variable displacement hydraulic pump and a variable displacement hydraulic motor in a transmission provided in a traveling vehicle such as a tractor.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in a work vehicle such as a tractor, a technique is known in which a hydraulic continuously variable transmission (hereinafter referred to as HST) is used as a main transmission and further provided with a sub-transmission to enable shifting. This is because the HST uses a variable displacement type hydraulic pump and a constant displacement type hydraulic motor, so that a multi-stage auxiliary transmission for increasing or decreasing the driving force is required after the HST. Each of these transmissions is provided with a transmission operation tool, and the main transmission is performed by connecting the swash plate of the hydraulic pump to the main transmission lever and rotating the main transmission lever. The sub-transmission device is configured as a gear selection type, and the slider is connected to the sub-transmission lever, and the sub-transmission lever is operated to perform sub-transmission, and each is operated separately. Also known is a technique in which a main shift operation is performed by a foot pedal.
[0003]
[Problems to be solved by the invention]
However, since the main speed change lever and the sub speed change lever are arranged at different positions, the number of lever operations increases to obtain a desired vehicle speed, which is complicated. In addition, since the sub-transmission device is configured as a gear selection type, when performing a sub-transmission operation, it can only be operated after the main clutch is operated to cut off the power transmission, resulting in reduced work efficiency and operability. Was getting worse.
[0004]
[Means for Solving the Problems]
The present invention uses the following means in order to solve the above problems.
In Claim 1, the hydraulic continuously variable transmission (23) which has a variable displacement type hydraulic pump (51) and a variable displacement type hydraulic motor (52) is mounted, and also this hydraulic continuously variable transmission (23) In a traveling vehicle in which a sub-transmission device (24) that enables further gear shifting is arranged at the rear stage, the movable swash plate (53) of the hydraulic pump (51) is interlocked with a foot pedal (15) that is a foot-operating gearshift operation tool. The foot pedal (15) is arranged as a forward pedal (15F) and a reverse pedal (15R) on the step (14), and the movable swash plate (54) of the hydraulic motor (52) is disposed on the actuator (55). The actuator (55) is connected to the switching valve (56), the solenoids (56a, 56b) of the switching valve (56) can be operated by the shift switch (59), and the seat (1 ) Is disposed near the auxiliary transmission lever (12) for operating the auxiliary transmission (24), and a shift switch (59) is provided in front of the grip (12a) of the auxiliary transmission lever (12). The hydraulic continuously variable transmission (23) is accelerated by rotating the shift switch (59) upward, and can be decelerated by rotating the shift switch (59) downward .
[0005]
According to a second aspect of the present invention, in the vehicle speed changing device according to the first aspect, the auxiliary transmission device (24) is constituted by a hydraulic clutch type transmission device that enables two-stage shift of high and low, and the auxiliary transmission lever (12). The switching valve (64) is operated by rotating the valve back and forth, and the low speed hydraulic clutch (65) or the high speed hydraulic clutch (66) is connected to enable the sub-shift operation .
[0006]
DETAILED DESCRIPTION OF THE INVENTION
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 accompanying drawings will be described. 1 is a side view of a tractor equipped with a speed change device of 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 speed change lever.
[0007]
First, a schematic configuration of a tractor which is an embodiment of a work vehicle provided with a speed change device according to the present invention will be described. In FIG. 1, an engine 2 is disposed in a bonnet 1 at the front of the machine, the engine 2 is covered with the bonnet 1, and a steering handle 17 serving as a steering means is projected on a dashboard 10 at the rear of the bonnet 1. ing. A seat 11 is disposed behind the steering handle 17, and a sub-shift lever 12 or a shift switch that serves as a shift operation tool for changing the angle of a sub-main shift described later and the movable swash plate 54 of the hydraulic motor 52 in the vicinity of the seat 11. 59, a working machine raising / lowering lever, etc. are arranged. On the step 14 between the dashboard 10 and the seat 11, a foot pedal 15 is disposed as a foot movement type main transmission operating tool, and is linked to a movable swash plate 53 of a hydraulic pump 51 described later. A portion where the auxiliary transmission lever 12, the foot pedal 15, the seat 11, the steering handle 17, and the like are disposed is a control unit 13 and is covered with the cabin 3.
[0008]
Further, front wheels 8 and 8 are supported on both sides of the front part of the machine, and rear wheels 6 and 6 are supported on both sides of the rear part. A mission case 5 is disposed below the seat 11, and a three-point link type work machine mounting device 4 for mounting various work machines is attached to the rear of the mission case 5. The PTO shaft 27 protrudes from the rear surface of the transmission case 5 so that the work machine can be driven. A front wheel power take-out case 7 is provided at the front lower portion of the transmission case 5, and transmits power to the front axle case through the transmission shaft 9 in front of the front wheel power take-out case 7, and is supported by the front axle case. 8 can be driven.
[0009]
Next, the drive transmission system of the tractor will be described with reference to FIG. Power is transmitted to the input shaft 33 of the hydraulic pump 51 of the HST (hydraulic continuously variable transmission) 23 disposed in the transmission case 5 via a damper or clutch (not shown) at the rear of the output shaft of the engine 2, The input shaft 33 extends rearward through the hydraulic pump 51, drives the hydraulic pump 51, and transmits power to the PTO shaft 27 via the PTO clutch 25 and the PTO transmission mechanism 26.
[0010]
A sub-transmission device 24 is provided on the rear side of the HST 23, that is, downstream of the power transmission path. The sub-transmission device 24 is capable of shifting with a hydraulic clutch. The speed can be changed by operating the low-speed clutch 65 or the high-speed clutch 66 by operating a switching valve 64 described later. The output shaft of the auxiliary transmission device 24 is the drive shaft 30, and power is transmitted to the rear wheel differential device 34 via a drive pinion 32 provided at the rear end of the drive shaft 30. The rear wheels 6 and 6 are driven via the differential yoke shafts 35L and 35R and the final reduction mechanisms 36 and 36.
[0011]
Further, a front wheel drive gear 40 is fixed on the drive shaft 30 and transmitted from the front wheel drive gear 40 to the front wheel transmission device 29 via two counter gears 41. The front-wheel transmission device 29 includes a hydraulic four-wheel drive clutch 37 and a front-wheel acceleration clutch 38. When both clutches are OFF, only the rear wheels are driven by two wheels and are operated on the road. When the four-wheel drive clutch 37 is turned on, the front wheels 8 and 8 and the rear wheels 6 and 6 are driven at the same speed, and are operated during work or the like. When the steering wheel 17 is rotated more than a set angle during operation, the front wheel acceleration clutch 38 is turned on to increase the driving speed of the front wheels 8 and 8 relative to the rear wheels 6 and 6 and drive at about twice the speed. I am doing so.
[0012]
The power after being shifted by the front wheel transmission device 29 is transmitted from the output shaft to the front differential device 43 in the front axle case through the transmission shaft 9, and the differential gear shafts 44 </ b> L on both sides of the front differential device 43 are transmitted. 44R, the front wheels 8 and 8 are driven via the final reduction mechanism 45.
[0013]
Next, a gear change device according to the present invention will be described. The HST 23 is composed of a variable displacement hydraulic pump 51 and a variable displacement hydraulic motor 52, and a movable swash plate 53 constituting the hydraulic pump 51 is a foot serving as a foot motion main transmission operating tool shown in FIGS. The foot pedal 15 is connected to a pedal (HST pedal) 15 via a link (not shown), and the foot pedal 15 is disposed on the control unit 13. In this embodiment, a forward pedal 15F and a reverse pedal 15R are disposed on the step 14. However, although the forward pedal 15F and the reverse pedal 15R are arranged side by side, the seesaw type can be configured so that a speed change operation can be performed with one foot pedal 15.
[0014]
By depressing the forward pedal 15F, the output shaft 31 of the hydraulic motor 52 is rotated forward, the movable swash plate 53 is also rotated and tilted in proportion to the rotational amount of the forward pedal 15F, and the discharge oil amount is inclined. The output rotation can be increased in proportion to the angle, and the forward main shift can be performed. When the reverse pedal 15R is depressed, the movable swash plate 53 is tilted in the opposite direction, the pressure oil is fed in the reverse direction, and the output shaft 31 of the hydraulic motor 52 is rotated in the reverse direction. An output rotation proportional to the rotation angle of the pedal 15R is obtained, and a reverse main shift can be performed.
[0015]
The movable swash plate 54 constituting the hydraulic motor 52 is connected to an actuator 55 via a link or the like (not shown), and the movable swash plate 54 is tilted by operating the actuator 55. Although the actuator 55 is a hydraulic cylinder in this embodiment, it can be constituted by a motor, a solenoid or the like, and is not limited.
[0016]
The actuator 55 is connected to a switching valve 56 through a flow control throttle and a check valve for preventing backflow. The switching valve 56 is constituted by an electromagnetic valve, and solenoids 56a and 56b of the switching valve 56 are connected to a controller 57. The controller 57 is connected to a shift switch 59 serving as a shift operation tool for driving the solenoids 56a and 56b. The controller 57 is connected to a sensor 58 that detects the operating position of the actuator 55.
[0017]
In addition, the shift switch 59 is disposed in the control unit 13 and is provided integrally with the auxiliary transmission lever 12 as shown in FIG. 4 so that the shift switch 59 can be easily operated. Yes. That is, the shift switch 59 is disposed on the side surface of the grip 12a of the auxiliary transmission lever 12, and is disposed on the front surface in this embodiment. However, it can also be arranged on the left and right sides. The shift switch 59 can be increased in speed by rotating upward, and can be decelerated by rotating downward. The shift operation tool is not limited to a lever switch, and can be increased / decreased by using two seesaw switches or push button switches, or can be increased / decreased by a dial, a knob, etc. using a volume.
[0018]
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 as to suck and discharge the hydraulic oil in the mission case 5. 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 is operated in a hydraulic cylinder in a hydraulic case placed on the transmission case 5. To lift the lift arm. Reference numeral 63 denotes a relief valve for setting the operating hydraulic pressure of the actuator 55. The tank port of the switching valve 56 is connected to the switching valve 64, and the secondary side of the switching valve 64 is connected to the low speed clutch 65 and the high speed clutch 66 of the auxiliary transmission 24 to rotate the auxiliary transmission lever 12. By moving, the switching valve 64 is switched, and the low speed clutch 65 or the high speed clutch 66 is operated to enable sub-shifting.
[0019]
In the above configuration, at the start of traveling, first, the auxiliary transmission 24 is shifted by the auxiliary transmission lever, and then the foot pedal 15 is depressed to perform the main transmission. This main speed change operation is performed by foot movement so that the operator can obtain a desired speed. By depressing the foot pedal 15, 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 travels at the desired speed set by the foot pedal 15 as described above, the speed may fluctuate depending on the load or the inclination of the work implement, or the current speed may be slightly increased or decreased. Then, the main transmission lever was turned, or the power transmission was cut off by stepping on the clutch pedal, and the sub-transmission device was used to change the speed. There was a limit to changing In addition, shifting the sub-transmission device temporarily interrupts the operation, which causes a delicate change in the finish, which is a troublesome operation.
[0020]
In the present invention, in such a case, the solenoid pump 51 is operated via the controller 57 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 as it is. 56 a (or 56 b) is operated to switch the switching valve 56, pressure oil is sent to the actuator 55, the hydraulic cylinder serving as the actuator 55 is expanded (or contracted), and the movable swash plate 54 of the hydraulic motor 52. Is tilted to change the rotational speed of the output shaft 31 so that the speed can be increased or decreased. At this time, with the pump capacity being constant, the movable swash plate 54 of the hydraulic motor 52 is tilted, and if this tilt angle is large, the motor capacity increases, the output rotation is decelerated, 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 speed is increased, and the work efficiency can be improved.
[0021]
The shift switch 59 is a neutral return type switch, and the actuator 55 is operated only when the speed is increased (UP) or decelerated (DOWN). The operating position of the actuator 55 is detected by the sensor 58. Can be operated up to the stroke limit. Further, 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, and the speed is controlled within a predetermined range at the next operation. Can be increased or decreased. Further, when the sub-shift is shifted to the high speed position, the vehicle has a maximum speed, so that the shift switch 59 can be operated within the range of the maximum speed or less.
[0022]
【The invention's effect】
Since the present invention is configured as described above, the following effects can be obtained.
As in claim 1, a hydraulic continuously variable transmission (23) having a variable displacement hydraulic pump (51) and a variable displacement hydraulic motor (52) is mounted, and the hydraulic continuously variable transmission (23) In a traveling vehicle in which a sub-transmission device (24) that enables further gear shifting is arranged at the rear stage, the movable swash plate (53) of the hydraulic pump (51) is interlocked with a foot pedal (15) that is a foot-operating gearshift operation tool. The foot pedal (15) is arranged as a forward pedal (15F) and a reverse pedal (15R) on the step (14), and the movable swash plate (54) of the hydraulic motor (52) is disposed on the actuator (55). The actuator (55) is connected to the switching valve (56), and the solenoids (56a, 56b) of the switching valve (56) can be operated by a shift switch (59), and the seat (11) A sub-transmission lever (12) for operating the sub-transmission device (24) is arranged in the vicinity, and a shift switch (59) is projected from the front surface of the grip (12a) of the sub-transmission lever (12). Since the hydraulic continuously variable transmission (23) is accelerated by rotating (59) upward and decelerated by rotating the shift switch (59) downward , the foot pedal (15 In addition to the main speed change operation by changing the movable swash plate of the hydraulic pump at), the variable swash plate of the hydraulic motor can be tilted by the operation of the shift switch (59), and the step size can be changed. Without changing, the operation range of multi-stage or continuously variable transmission operation can be expanded, and continuously variable transmission can be performed with simple operation without disengaging the clutch.
In addition, the traveling speed can be changed manually while performing the main shifting operation with the foot, and the setting range of the traveling speed can be expanded to easily change to the desired shifting speed.
[0023]
Further, when the capacity of the hydraulic pump is increased and the capacity of the hydraulic motor is increased to work at a low speed, the output torque can be increased, and when the capacity of the hydraulic motor is decreased, 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 can be achieved and work accuracy can be improved. In this way, the movable swash plate of the hydraulic pump and hydraulic motor can be tilted to increase the capacity. By changing, it became possible to handle various work and expanded the work area.
In addition, since the shift operating tool is constituted by a switch and the shift operating tool is disposed on the sub-shift lever, the shift switch can be operated while holding the sub-shift lever during driving operation. The operability of the shift operation can be improved.
[0024]
According to a second aspect of the present invention, in the vehicle speed changing device according to the first aspect, the auxiliary transmission (24) is constituted by a hydraulic clutch type transmission that enables two-stage shift of high and low, and the auxiliary transmission lever ( 12) By operating the switching valve (64) by rotating back and forth in 12) and connecting the low-speed hydraulic clutch (65) or the high-speed hydraulic clutch (66) to enable the sub-shift operation, Since the auxiliary transmission is configured as a gear selection type, when operating the auxiliary transmission lever, it can only be operated after the main clutch is operated and the power transmission is cut off. The problem that the operability had deteriorated could be solved.
As a result, both the auxiliary transmission lever (12) and the shift switch (59) can perform a shifting operation without operating the main clutch.
[Brief description of the drawings]
FIG. 1 is a side view of a tractor equipped with a speed change 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]
12 Sub-shift 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 operation tool)

Claims (2)

A hydraulic continuously variable transmission (23) having a variable displacement hydraulic pump (51) and a variable displacement hydraulic motor (52) is mounted, and further a shift is performed on the subsequent stage of the hydraulic continuously variable transmission (23). In a traveling vehicle in which an auxiliary transmission (24) that can be used is arranged, the movable swash plate (53) of the hydraulic pump (51) is interlocked and connected to a foot pedal (15) that is a foot-operated gear shifting operation tool, and the foot pedal (15) is arranged as a forward pedal (15F) and a reverse pedal (15R) on the step (14), and the movable swash plate (54) of the hydraulic motor (52) is interlocked with the actuator (55), The actuator (55) is connected to the switching valve (56), and the solenoids (56a, 56b) of the switching valve (56) can be operated by a shift switch (59), and the sub-change in the vicinity of the seat (11). A sub-transmission lever (12) for operating the device (24) is arranged, a shift switch (59) is projected from the front surface of the grip (12a) of the sub-transmission lever (12), and the shift switch (59) is moved upward. The vehicle speed changing device is characterized in that the hydraulic continuously variable transmission (23) is accelerated by rotating to a speed and the shift switch (59) can be decelerated by rotating downward . 2. The vehicle speed changing device according to claim 1, wherein the auxiliary transmission (24) is constituted by a hydraulic clutch type transmission capable of two-step shift of high and low, and the auxiliary transmission lever (12) is rotated forward and backward. A vehicle speed changing device characterized in that a sub-shift operation can be performed by operating a switching valve (64) by operation and connecting a low speed hydraulic clutch (65) or a high speed hydraulic clutch (66) .

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