JPH1030721A - Travel transmission structure of work vehicle - Google Patents

Abstract

(57) Abstract: A transmission structure capable of suppressing a shock at the start of transmission after driving a shift member of a subtransmission to a speed increasing position is rationally configured. SOLUTION: A sleeve 15 is moved to a high speed position H and a low speed position L.
And the auxiliary transmission A which shifts between high and low by switching to
And a main transmission that is shifted by selective operation of a plurality of hydraulic clutches are arranged in series between the engine and the crawler traveling device, and the sleeve 15 is switched between the high-speed position H and the low-speed position L. A double-acting hydraulic cylinder D is provided, and the speed at which the sleeve 15 is switched from the low-speed position L to the high-speed position H is higher than the operating speed in the opposite direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine comprising a first transmission mechanism which is shifted by changing the shift position of a shift member and a second transmission mechanism which is shifted by selectively engaging a plurality of hydraulic clutches. The present invention relates to an improvement in a traveling power transmission structure of a work vehicle arranged in series between a vehicle and a traveling device.

[0002]

2. Description of the Related Art Conventionally, a combine vehicle is described as an example of a work vehicle constructed as described above.
In this conventional example, a plurality of shift hydraulic clutches are connected via a subtransmission (first transmission mechanism) having a transmission gear that is operated to slide power from an engine. The traveling transmission structure is configured to transmit the transmitted power to the main transmission (second transmission mechanism) and further to the left and right crawler traveling devices via the traveling clutch. Further, in this conventional example, the auxiliary transmission is configured to be operated by an operation force (usually a manual operation force) from outside the transmission case.

[0003]

In the transmission structure constructed as in the prior art, the auxiliary transmission mechanism is operated by a separate operation from the speed change operation of the main transmission mechanism. Even if the user wishes to change the traveling speed by operating the auxiliary transmission at the same time as the gear shifting operation, it is necessary to change the operation of the operating tool for shifting the main transmission mechanism and the operating tool for shifting the auxiliary transmission mechanism, Not only does the operation become cumbersome, but it also takes time to complete the shift, leaving room for improvement.

Therefore, a hydraulic actuator for shifting the speed change mechanism by the driving force is provided, and an operating tool such as a single shift lever for controlling the hydraulic actuator and the hydraulic clutch of the main transmission is provided. When speed is increased, the traveling speed is increased by selectively engaging a plurality of hydraulic clutches by operating the operation lever, and when further increasing the speed with the hydraulic gear at the highest gear, It is conceivable to operate the auxiliary transmission at an increased speed, and at the same time, set the main transmission mechanism to an appropriate gear. However, when increasing the speed of the vehicle body, the traveling speed decreases due to the resistance acting on the traveling device when the transmission is interrupted during the shift operation.
In addition, since the operation of changing the position of the shift member takes more time than the operation of turning on and off the hydraulic clutch, the shift is completed at the time of this shift operation, and when the shifted power is transmitted to the traveling system, the shift of the vehicle body is performed. There is room for improvement because the difference between the actual traveling speed and the transmission speed transmitted to the traveling device may increase to cause a shock.

SUMMARY OF THE INVENTION An object of the present invention is to provide a transmission structure having a first transmission mechanism for shifting by changing the position of a shift member and a second transmission mechanism for shifting by a plurality of hydraulic clutches. The present invention is characterized in that a transmission structure capable of increasing the speed by operating the shift member of the first transmission mechanism without causing the driver to feel it and suppressing generation of a shock during the speed increase is rationally configured.

[0006]

According to a first aspect of the present invention, as described at the outset, a first speed change mechanism which is shifted by changing a shift position of a shift member, and a plurality of hydraulic systems are provided. In a traveling power transmission structure for a work vehicle in which a second transmission mechanism that is shifted by selective engagement of a clutch is arranged in series between an engine and a traveling device, the first transmission mechanism is in a high-speed transmission state and a low-speed transmission state. And an actuator for switching the shift position of the shift member between a high-speed transmission position and a low-speed transmission position. The actuator operates the shift member from the low-speed transmission position to the high-speed transmission position. The speed at which the operation is switched to is set higher than the operation speed in the opposite direction, and the operation is as follows.

A second feature of the present invention (claim 2) is that the actuator is a double-acting hydraulic cylinder in which a piston rod is formed on one side along a working direction of the piston from a piston built in the cylinder. And the linkage between the hydraulic cylinder and the shift member is set so as to operate the shift member to the high-speed transmission position by supplying hydraulic oil to the hydraulic cylinder on the side where the piston rod is disposed. The operation is as follows.

According to the first feature, the first transmission mechanism can be shifted by the actuator, and the actuator operates at a high speed when the first transmission mechanism is switched to the high-speed transmission state. This shortens the time from the start of shifting to the end of shifting. For example, when the second shifting mechanism reaches the highest speed and switches to the next shift speed, the first shifting mechanism is switched from the low-speed transmission state to the high-speed transmission state. Can shorten the time during which power is not transmitted to the traveling device, and reduce the speed difference between the traveling speed of the vehicle body before shifting and the shifting power.

According to the second feature, since the pressure receiving surface of the piston provided with the piston rod is smaller than the other pressure receiving surface of the piston, for example, an operation from a supply system such as a predetermined hydraulic pump is performed. As a result of operating the shift member to the high-speed transmission position at a higher speed, supplying oil to the side with a smaller pressure receiving area is faster than supplying oil to the side with a larger pressure receiving area just by supplying oil. It can be done in.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, in a combine as an example of a work vehicle, a transmission case M is configured as a transmission case for transmitting the shifting power from the engine E to the crawler traveling device CR. The transmission case M is provided with an input pulley 1 at the upper portion to which the power from the engine E is input, and an output pulley 2 to which a driving force synchronized with the traveling speed from the transmission case M is transmitted. As shown in the figure, an auxiliary transmission device A (an example of a single transmission mechanism) capable of switching the power from an input shaft 3 connected to an input pulley 2 to a two-speed state of a high-speed transmission state and a low-speed transmission state.
And the power from the auxiliary transmission A is transferred to three forward speeds and one reverse speed.
Main transmission device B (example of second transmission mechanism) switchable to gear
And the left and right steering clutches 4 for transmitting the power from the main transmission B to the left and right crawler traveling devices CR, CR.
4 and a pair of left and right brake mechanisms 5 and 5 for selectively applying a braking force to the left and right traveling transmission systems, and the power from the steering clutch 4 is supplied to the left and right drive shafts 6 and The power from the input shaft 3 is transmitted to the sprockets 7 and 7 for driving the left and right crawler traveling devices CR and CR through the gear transmission mechanism 8 and the output shaft 9, respectively. A power transmission system for transmitting to the pulley 2 is formed, and the power from the output pulley 2 is configured to be transmitted to a pre-cutting processing unit (not shown) including a raising device, a cutting device, a grain culm conveying device, and the like. .

As shown in FIGS. 2 and 3, the auxiliary transmission A includes a pair of high-speed transmissions which are provided so as to always mesh with the input shaft 3 and the intermediate shaft 10 in a posture parallel to the input shaft 3. Gears 11 and 12 and a pair of low-speed transmission gears 13 and 14
And the input shaft 3 is provided with engaging pawls 15A, 15A at both ends so as to be detachable from the engaging pawls 11A, 13A of the high-speed transmission gear 11 and the low-speed transmission gear 13, respectively. And a clutch sleeve 15 as a shift member slidably provided in the axial direction via a portion. The gears 11 and 13 on the input shaft 3 side are idlely supported by the input shaft 3, and the intermediate shaft 10. Gears 12 and 14 are fixed to the intermediate shaft 10, and are configured to transmit the power from the input shaft 3 to the intermediate shaft 10 by operating the clutch sleeve 15 so that the respective occlusal claws reach the occlusal state. Have been.
Further, the auxiliary transmission A is configured to be switched by a hydraulic cylinder D as an actuator built in the transmission case M.

That is, as shown in FIG. 3, the hydraulic cylinder D is of a double-acting type in which a piston rod 17A is formed on one side along the operating direction from a piston 17 housed in a cylinder case 16. By engaging a shifter 18 provided at 17A with the clutch sleeve 15, the auxiliary transmission A can be switched from a neutral position N shown in the same figure to a high-speed transmission position H and a low-speed transmission position L, and The cylinder case 16 has a pair of oil passages 19, 19 for reciprocating the piston 17, and the piston 17.
The control oil passage 20 which sends out the operating oil in the cylinder case 16 after the auxiliary transmission A reaches the transmission state by the engagement of the engagement claw 15A of the clutch sleeve 15 with the engagement claw of one of the gears by the operation of the clutch sleeve 15 is formed. ing. The three oil passages 19, 19, 20 are connected to a rotary valve V (FIG. 1) through an oil passage (not shown) formed inside an oil passage plate 21 attached to the outer surface of the transmission case M. , See FIG. 6).

As shown in FIG. 2, the main transmission B shifts the power from the intermediate shaft 10 to three different speeds in the forward direction, and is a wet multi-plate type first, second, and third type for forward speed change. A constant-mesh-type gear transmission system for transmitting to the third hydraulic clutches C1, C2, and C3, and the power from the intermediate shaft 10 is shifted in the reverse direction and transmitted to the fourth wet-disc fourth hydraulic clutch C4 for reverse. And the left and right steering clutches 4, 4 are provided with first, second, third, and fourth hydraulic clutches C1,
Transmission gear 2 that can be transmitted when entering C2, C3, and C4
A pair of clutch members configured to be slidable with respect to a transmission shaft 24A that rotates integrally with the transmission gear 24 so as to switch between a state in which the power from the drive gear 4 is transmitted to the left and right drive shafts 6 and a state in which the power is interrupted. 4A, 4A, the brake mechanisms 5, 5 act on the drive shafts 6, 6 on the disengagement side by further operating in the same direction with the clutch member 4A disengaged. It is disposed adjacent to the steering clutches 4, 4 on the same axis as the transmission shaft 24A so as to perform the rotation. Further, as shown in FIG. 1, arms 26, 26 operated by ram cylinders 25, 25 are provided on the front surface of the transmission case M so that the left and right steering clutches 4, 4 can be operated independently.

In this traveling transmission structure, a rotary valve V as a hydraulic control mechanism built in the transmission case M
Thus, the sub-transmission A and the main transmission B are controlled so that a continuous shift can be performed.

As shown in FIG. 6, the rotary valve V is in the neutral position N, the first forward speed F1 to the sixth forward speed F6,
It is configured to be freely operable at nine positions of a speed R1 and a reverse second speed R2. As shown in FIGS. 1, 4, and 5, a pinion gear 27 is provided at an end of the rotary spool VS of the rotary valve V outside the transmission case. A sector gear 28 meshing with the pinion gear 27 is provided on the upper part of the transmission case M so as to be swingable around a lateral support shaft 29, and a shift lever 30 as an operating tool is provided for the support shaft 29.
Also, the plate section integrally formed with the sector gear 28 has a 9
Are formed, and a roller 31 engaged with and disengaged from the concave portion 29A is rotatably supported on an arm 33 swingably supported on a lateral shaft 32 on a rear surface of the transmission case M. By providing a spring 34 for urging the arm 33 to the side where the roller 31 is engaged with 26A,
The shift operation is performed by swinging the shift lever 30 in the front-rear direction.

As shown in FIGS. 4 and 6, an accumulator 35 is provided inside the rotary spool VS of the rotary valve V, and the oil controlled by the rotary valve V is disposed above the transmission case M. Oil passage plate 2
1 to the hydraulic cylinder D, and, as shown in FIG. 1, through an oil passage (not shown) formed inside an oil passage plate 36 formed on the side surface of the transmission case M. These are sent to the four hydraulic clutches C1, C2, C3, and C4. Further, as shown in FIG. 6, a hydraulic system controlled by the rotary valve V is configured, and the shifting operation will be described below. That is, when the rotary valve V is operated to the first forward speed F1 from the neutral position N, the pressure oil from the hydraulic pump P is sent to the oil passage on the low-speed operation side of the hydraulic cylinder D, and the operation of the piston 17 causes the clutch sleeve to operate. At the timing when the motor 15 reaches the transmission state, the pressure oil is returned to the rotary valve V via the control oil passage 20 which has been interrupted by the piston 17 and is supplied to the first hydraulic clutch C1 while increasing the pressure by the accumulator 35. As a result, a shift state of the first forward speed F1 is obtained by the smooth engagement operation of the first hydraulic clutch C1.

FIG. 1 shows a state in which the auxiliary transmission A is maintained at the neutral position N while the rotary valve V is at the neutral position N. At the time of operating to F1, usually the hydraulic cylinder D
Is normally on the low-speed transmission side (the sub-transmission is in the low-speed transmission state), for example, when the engine is stopped when the vehicle is traveling at the fourth forward speed F4 or higher, and then this shift is performed. The piston 17 does not operate except in special situations such as

Next, when the rotary valve V is operated to the second forward speed F2, oil is discharged from the first hydraulic clutch C1 via the rotary valve V and the first hydraulic clutch C
1 is turned off, and since the piston 17 of the hydraulic cylinder D is already on the low-speed transmission side, the pressure oil returned to the spool 17 through the control oil passage 20 increases the pressure in the accumulator 35 while the second hydraulic pressure is increased. The clutch 2 is supplied to the clutch 2, and as a result, the forward 2
The speed change state of the speed F2 is obtained. Further, when the rotary valve is operated to the third forward speed F3, the same speed change operation is performed.

Next, when the rotary valve V is operated from the third forward speed F3 to the fourth forward speed F4, the rotary valve V
, The third hydraulic clutch C3 is drained and the third hydraulic clutch C3 is turned off, and the pressure oil from the hydraulic pump P is sent to the oil passage on the high-speed operation side of the hydraulic cylinder D, The operation of the piston 17 causes the clutch sleeve 15 to reach the transmission state, and at this timing when the transmission state is reached, the pressure oil blocked by the piston 17 is returned to the rotary valve V via the control oil passage. The pressurized oil is supplied to the first hydraulic clutch C1 while increasing the pressure by the accumulator 35, so that the shift state of the fourth forward speed F4 is obtained by the smooth engagement operation of the first hydraulic clutch C1.

As described above, the traveling speed of the vehicle body is changed to the third forward speed F
When the gear is operated from the third forward speed F4 to the fourth forward speed F4, the auxiliary transmission A is switched, so that the shifted power is compared with the speed at the time of shifting from the first forward speed F1 to the third forward speed F3.
Since it takes some time before the power is transmitted to R, a high-speed transmission is performed after the traveling speed is reduced. Therefore, a shock tends to occur. However, as shown in FIG. Intermediate position NF not formed as a shift position between third speed F3 and fourth forward speed F4
At the same time, the orifice 37 for suppressing the amount of oil discharged from the accumulator 35 is formed to shorten the time until the first hydraulic clutch C1 reaches the on state, and at the same time, the auxiliary transmission A is moved from the low-speed transmission position in this manner. When switching to the high-speed transmission position, as shown in FIG.
A is formed so that hydraulic oil from the hydraulic pump P is supplied to the side of the pressure receiving area smaller than the pressure receiving area of the piston 17 on the opposite side, and the auxiliary transmission A is promptly switched to operate the traveling speed during the shift. Can be suppressed. The shift operation when the rotary valve V was operated from the fourth forward speed F4 to the sixth forward speed F6 was performed from the second forward speed F2 to the fourth forward speed F4 except that the auxiliary transmission A was at the high-speed transmission position H. The same control as in the case is performed.

Next, when the rotary valve V is operated to the reverse first speed R1 from the neutral position N shown in FIG. 6, the hydraulic oil from the hydraulic pump P is sent to the oil passage on the low speed operation side of the hydraulic cylinder D. , The pressure oil is supplied via the control oil passage 20 to the rotary valve V.
And is supplied to the fourth hydraulic clutch C4 while increasing the pressure by the accumulator 35. As a result, the shifting state of the first reverse speed R1 is obtained by the engagement operation of the fourth hydraulic clutch C4.

Next, when the rotary valve is operated from the reverse first speed R1 to the reverse second speed R2, the rotary valve is not formed as the shift position of the rotary valve, but is operated at the reverse first speed R1.
Oil is drained from the fourth hydraulic clutch C4 via the rotary valve V at the shift position NR at an intermediate position between the second hydraulic speed R2 and the reverse second speed R2, the fourth hydraulic clutch C4 is once turned off, and the rotary valve V is turned off. The pressure oil from the hydraulic pump P is sent to the oil passage on the high-speed operation side of the hydraulic cylinder D via the hydraulic pump D, and the control oil passage that is interrupted by the piston 17 at the timing when the clutch sleeve 15 reaches the transmission state by the operation of the piston 17. The pressurized oil is returned to the rotary valve V via 20 and this pressure oil is supplied to the fourth hydraulic clutch C4 while increasing the pressure by the accumulator 35. Therefore, when the fourth hydraulic clutch C4 is engaged, the reverse second speed is established. The shift state of R2 is obtained. When performing this shift, the fourth
Unlike the above-described shift position NF, the orifice is not formed so as to quickly drain the oil from the accumulator 35 so that the engagement operation of the hydraulic clutch C4 is not performed at a very high speed.

Although only the gear shifting operation to the speed increasing side has been described above, the hydraulic clutch to which the hydraulic oil is supplied from the rotary valve V at the time of gear shifting in the deceleration direction is switched from a high speed clutch to a lower speed clutch. The basic operation of the sub-transmission A is the same as that of the sub-transmission A only by switching from the high-speed transmission state to the low-speed transmission state.

As described above, in the present invention, the transmission case M is provided with the hydraulic cylinder D for driving and operating the clutch sleeve 15 of the auxiliary transmission A, and the hydraulic cylinder D and the four hydraulic clutches C1 of the main transmission B are provided. , C2, C3,
Rotary valve V for controlling C4 is changed to transmission case M
, The clutch sleeve 15 of the auxiliary transmission A can be reliably shifted to a position where the transmission is switched at the time of gear shifting, while having a simple structure, and the rotary valve V is formed via an oil passage formed integrally with the transmission case M. Hydraulic oil to hydraulic cylinder D and four hydraulic clutches C1, C
2, C3 and C4.

When the shift lever 30 is operated to increase the vehicle speed and switch from the third forward speed F3 to the fourth forward speed F4, the third hydraulic clutch C3 in the transmission state is activated prior to the start of the operation of the hydraulic cylinder D of the auxiliary transmission A. Since the disengagement operation is started, the hydraulic cylinder D operates in a state where the transmission from the engine E to the crawler traveling device CR is cut off, and the engagement operation of the first hydraulic clutch C1 is started after the operation of the hydraulic cylinder D is started. When the transmission of the engine E to the crawler traveling device CR is cut off, the hydraulic cylinder D is operated, and after the auxiliary transmission A has reached the transmission state, the main transmission B can be switched to the transmission state. This allows for smooth shifting. In particular, since the hydraulic oil is supplied to the side of the cylinder case 16 of the hydraulic cylinder D provided with the piston rod 17A during this shift, the piston 17 is operated at a higher speed as compared with the case where the hydraulic oil is supplied to the opposite side. This makes it possible to shorten the shift time, for example, when shifting in an environment where the vehicle speed is likely to decrease, such as when traveling on a mud surface containing a lot of moisture,
The shock is generated by minimizing the difference between the driving speed of the power transmitted to the traveling system after the shift is completed before the traveling speed is significantly reduced and the operation speed of the crawler traveling device CR caused by the dynamic inertia of the vehicle body. It can be suppressed. Further, when the traveling speed is changed from the fourth forward speed F4 to the third forward speed F3, the vehicle speed is reduced, so that no shock is generated even when the sub-transmission A is switched at a lower speed than when the speed is increased. It has become.

[Other Embodiments] In the present invention, besides the above-mentioned embodiment, for example, the actuator may be constituted by an electric motor or a hydraulic motor according to the first aspect.

[0027]

Therefore, the transmission structure can increase the speed by operating the shift member of the first transmission mechanism without causing the operator to feel troublesome, and can suppress the occurrence of a shock during the speed increase. Was reasonably constituted (claim 1). Further, by using the structure of the double-acting hydraulic cylinder, the first transmission mechanism can be quickly switched to the high-speed transmission position without changing the hydraulic oil amount of the hydraulic oil supply system or the like. (Claim 2).

[Brief description of the drawings]

FIG. 1 is a side view of a transmission case.

FIG. 2 is a schematic diagram showing a transmission system in a transmission case.

FIG. 3 is a sectional view showing an auxiliary speed change operation system.

FIG. 4 is a schematic view of a rotary valve.

FIG. 5 is a side view of a transmission case.

FIG. 6 is a hydraulic circuit diagram for shifting.

[Explanation of symbols]

 15 Shift member 16 Cylinder 17 Piston 17A Piston rod A First transmission mechanism B Second transmission mechanism CR Traveling device D Actuator E Engine H High-speed transmission position L Low-speed transmission position

Claims (2)

[Claims] 1. A first transmission mechanism, which is shifted by changing a shift position of a shift member, and a second transmission mechanism, which is shifted by selectively engaging a plurality of hydraulic clutches, between an engine and a traveling device. A traveling transmission structure of a working vehicle arranged in series with the first transmission mechanism, wherein the first transmission mechanism is configured to switch between a high-speed transmission state and a low-speed transmission state.
An actuator for switching the shift position of the shift member between a high-speed transmission position and a low-speed transmission position, and a speed for switching the operation speed of the actuator from the low-speed transmission position to the high-speed transmission position. Is set at a speed higher than the operating speed in the opposite direction. 2. The actuator according to claim 1, wherein the actuator comprises a double-acting hydraulic cylinder having a piston rod formed on one side of a piston provided in the cylinder along an operation direction of the piston. The traveling transmission structure for a work vehicle according to claim 1, wherein the linkage between the hydraulic cylinder and the shift member is set so that the shift member is operated to the high-speed transmission position by supplying the hydraulic oil to the hydraulic cylinder.