JPH1054461A - Continuously variable transmission for working machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a working machine capable of smoothly advancing a machine body from a state where the machine body is completely stopped by the operation of a shift operating tool without generating shock. SOLUTION: A continuously variable transmission system for advancing a machine body by supplying operating oil from a variable displacement hydraulic pump P to a hydraulic motor M through a first passage D1 and for reversing the machine body by supplying operating oil from the hydraulic pump P to the hydraulic motor M through a second oil passage D2 is constituted, and a neutral valve 49 for releasing pressure of the second oil passage D2 to a drain passage by the releasing operation when a shift lever is set in the neutral position is so provided as to be freely operated by a linking means K.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement hydraulic pump driven by an engine, a hydraulic motor that converts hydraulic oil supplied from the hydraulic pump into rotational force and transmits it to a traveling system, and a hydraulic pump. A first oil passage formed between the hydraulic pump and the hydraulic motor, a second oil passage formed between the hydraulic pump and the hydraulic motor, and a shift operation tool for controlling the hydraulic pump The greater the amount of operation of the shift operation tool from the neutral position to the forward range, the greater the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic motor through the first oil passage, and the reverse of the shift operation tool from the neutral position. The larger the operation in the region, the greater the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic motor via the second oil passage, and when the shift operation tool is set to the neutral position, the hydraulic oil flows to the first oil passage and the second oil passage, respectively. Hydraulic fluid supply To an improvement of the continuously variable transmission Kusuru so speed change operation device and the working machine and a hydraulic pump are then linked.

[0002]

2. Description of the Related Art Conventionally, as an example of a continuously variable transmission constructed as described above, which is provided on an agricultural tractor, Japanese Patent Application Laid-Open No. 62-137224 or Japanese Patent Application Laid-open No.
Japanese Patent Application Laid-Open No. 137223/1987 discloses a conventional one of these conventional examples, in which a pair of a first oil passage for forward movement and a second oil passage for reverse movement is provided between a hydraulic motor and a hydraulic pump. And a pair of neutral valves (opening / closing valves) so as to release the pressure of each of the first oil passage and the second oil passage to a drain oil passage (discharge oil passage). The pilot pressure operation type is configured to perform a closing operation with an increase in the pressure of the oil passage and an opening operation with a decrease in the pressure. Further, in the latter conventional example, a pair of oil passages of a first oil passage for forward movement and a second oil passage for backward movement are formed between a hydraulic motor and a hydraulic pump, and these first oil passages are formed. A pair of neutral valves (opening / closing valves) for releasing the pressure of each of the second oil passages to a drain oil passage (discharge oil passage), and a potentiometer for measuring an operation amount of a shift operation tool (foot pedal). The hydraulic pump is controlled by measuring the operation amount of the shift operation tool based on the signal from the potentiometer, and when the shift operation tool is determined to be in the neutral position based on the signal from the potentiometer, each neutral valve is activated. The neutral valve is electrically operated so as to release the first oil passage, the second oil passage and the pressure to the drain oil passage by performing an opening operation.

[0003]

Considering the above prior art examples, in any of the prior art examples, when the shift operation tool is near the neutral position, even if the hydraulic oil is actually slightly discharged from the hydraulic pump. In addition, the action of the pressure of the hydraulic oil on the hydraulic motor is completely released by the opening operation of the neutral valve, so that the phenomenon that the body moves at a very low speed does not occur. However, for example, in a linkage in which hydraulic oil is slightly sent out from the hydraulic pump to the first oil path in a state where the shift operation tool is in the neutral position, the neutral valve is in a state where the shift operation tool is in the neutral position. When the shift operation device is operated forward from this state, the supply of hydraulic oil to the first oil passage is increased to some extent, and the neutral state is prevented. Since the valve closes and hydraulic oil from the hydraulic pump is supplied to the hydraulic motor, a shock may be generated at the start of traveling.

In order to solve this inconvenience, when the shift operating device is in the neutral position without a neutral valve, the linkage between the shift operating device and the hydraulic pump is adjusted so that hydraulic oil is not discharged from the hydraulic pump. It is necessary, but there is room for improvement in such a device that requires precise adjustment because the adjustment is troublesome. In particular, in a working machine equipped with this type of continuously variable transmission, there is a high frequency of an operation of moving the machine from a stopped state to move forward. Therefore, a technique for reducing a shock at the start of moving forward is desired.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent the body from moving at a very low speed when the shift operation tool is set to the neutral position, and to prevent the occurrence of a shock when the body is advanced from a stopped state. The point is that the continuously variable transmission is rationally configured.

[0006]

According to a first aspect of the present invention, as described at the outset, a variable displacement hydraulic pump, a hydraulic motor for driving the vehicle, and a hydraulic motor for moving the body are provided. In a continuously variable transmission for a working machine including one oil passage, a second oil passage for reversing the fuselage, and a shift operation tool for controlling a hydraulic pump,
When the speed change operation tool is set to the neutral position, a neutral valve is provided to release the pressure of the second oil passage to the drain oil passage by the opening operation by the operation of the operation means, and the operation is as follows. It is.

A second feature of the present invention (claim 2) is that the operating means opens a neutral valve as the pressure in the second oil passage decreases and neutralizes as the pressure in the second oil passage increases. In order to close the valve, a pilot oil passage directly acting on the neutral valve is provided, and the operation is as follows.

A third feature of the present invention (claim 3) is that the shift setting system includes a potentiometer for measuring a shift set position, the neutral valve is configured to be an electromagnetically operated type, and the operating means is configured by a potentiometer. The control system operates the neutral valve to the open position when it is determined that the speed change setting system is in the neutral position based on the above signal. The operation is as follows.

According to the first feature, when the shift operation tool is set to the neutral position, the operating means opens the neutral valve to release the pressure of the second oil passage to the drain oil passage. When the body is completely stopped and the shift operation device is operated from the neutral position to the forward side, the shift operation device is neutralized without operating the stroke for closing the neutral valve as in the conventional example. The hydraulic oil can be supplied to the first oil passage only by operating the device slightly forward from the position.
An amount of hydraulic oil corresponding to the operation of the operation amount of the operation tool can be sent. That is, in the present invention, the neutral valve is provided only on the side of the oil passage for moving the body backward. However, when the shift operation tool is set to the neutral position, the hydraulic pump does not need to be accurately set to the neutral position. To allow the hydraulic fluid to flow slightly to the side of the second oil passage, thereby avoiding the phenomenon that the traveling body moves at a very low speed with the shift operation tool in the neutral position. When the shift operation tool is operated from the neutral position to the forward side, even if the neutral valve is in the open state, the hydraulic oil is immediately supplied to the first oil passage to enable the forward movement of the body. .

According to the second feature, since the operating means can be formed by an oil passage or the like, it has a simple structure which does not use a movable member or the like as compared with a mechanism in which a shift setting system and a neutral valve are mechanically linked. The neutral valve can be operated.

According to the third feature, since the neutral position of the shift setting system is electrically measured to open the electromagnetically operated neutral valve, the operating means is compared with a mechanically linked neutral valve. As a result, the opening and closing operation of the neutral valve can be quickly performed, and at the same time, the neutral position can be easily set by electrical processing.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. As shown in FIG. 1, a drive-type front wheel 1 and a drive-type rear wheel 2 that are steered.
The engine 4 is mounted on the front part of the traveling body 3 provided with a hydraulic motor, and a hydrostatic continuously variable transmission 5 to which power from the engine 4 is transmitted and a transmission case 6 are arranged on the rear part of the traveling body 3. A rear axle case 7 for transmitting the power from the transmission case 6 to the rear wheels 2 is provided in a connected state with the transmission case 6, and a front axle case 8 for transmitting the power from the transmission case 6 to the front wheels 1 is provided at the center of the fuselage. And a driver's seat 9 in the center of the traveling body 3,
A seedling planting apparatus A is connected to a rear end of the traveling machine body 3 via a link mechanism 11 driven up and down by a lift cylinder 10 to constitute a riding type rice transplanter as a working machine.

A raising / lowering lever 12 is provided on the right side of the driver's seat 9 for raising and lowering the seedling planting device A and performing an on / off operation of a planting clutch C (described later). A main speed change lever 13 as a speed change operation tool for operating the transmission 5 is disposed, and a gear type auxiliary speed change mechanism (described later) in the transmission case 6 is provided on the left side of the driver's seat 9.
Is provided. The planting clutch C is built in the transmission case 6,
The cutting operation is allowed only when the transmission shaft 15 for transmitting power from the transmission case 6 to the seedling planting device A is in a predetermined rotation phase, and the planting arm (described later) of the seedling planting device A is moved to the field. The power is cut off in a posture avoiding contact with the vehicle.

The seedling plant A is mounted on the seedling table 18 by operating a planting mechanism comprising a pair of planting arms 17, 17 provided on a rotary case 16 by power transmitted through the transmission shaft 15. The placed mat-shaped seedlings W are cut out with the planting claws of the planting arm 17 and transplanted one by one to the field scene.

As shown in FIG. 2, a transmission system from the engine 4 to the continuously variable transmission 5 is formed. In this transmission system, a first intermediate member connected to an output shaft 4A of the engine 4 via a rubber coupling 21 is formed. A shaft 22, a multi-plate type main clutch 23 connected to the rear end of the first intermediate shaft 22 via a rubber coupling 21, power is transmitted from the main clutch 23, and the front axle case 8 is moved back and forth. A second intermediate shaft 24 penetrating in the direction, and power is transmitted from the second intermediate shaft 24, and an Oldham joint type joint J, J at both ends so as to transmit power to the input shaft 5A of the continuously variable transmission 5. The third intermediate shafts 25 each having a J are provided. Also, the power from the traveling transmission shaft 26 penetrating from the rear side to the front side of the continuously variable transmission 5 is transmitted to the front wheel case 8 so that the transmission power from the transmission case 6 is transmitted to the front wheels 1.
A drive transmission system is provided with a drive shaft 28 having ubiquitous joints 27, 27 at both ends so as to transmit the input shaft 8A.

As shown in FIG. 3, the Oldham joint type joints J, J are articulated members 29 externally supported by splines at both ends of a third intermediate shaft 25, and articulated claws of the respective articulated members 29. 29A includes an occlusal member 30 having an occlusal groove 30A into which the occlusal groove 29A engages.
Of the occlusal claw 29A in the radial direction and
By setting a phase difference of 0 degrees (postures orthogonal to each other), the displacement of the shaft center during transmission is absorbed by the joints J and J, thereby enabling smooth transmission while preventing generation of abnormal noise. Has become.

As shown in FIG. 4, the continuously variable transmission 5 is driven by a variable displacement hydraulic pump P driven by power from an input shaft 5A and a hydraulic oil supplied from the hydraulic pump P. The transmission case 6 is provided with a hydraulic motor M (to be described in detail later), and a gear type in which the power from the first shaft 33 to which the transmission power from the hydraulic motor M is transmitted is operated by the auxiliary transmission lever 14 inside the transmission case 6. And a power transmission system for transmitting the power transmitted to the differential mechanism 35 of the rear wheel 2 via the auxiliary transmission mechanism 34 to the traveling transmission shaft 2.
6 for transmitting the power from the first shaft 33 to the second shaft 3
6 through a gear provided in the third shaft 37 to a gear transmission system, and the power from the third shaft 37 is further geared to the fourth shaft 3.
8 and a fifth shaft 39, and the power from the fifth shaft 39 is transmitted to the first power take-out shaft 39 on the rear surface of the transmission case 6.
A, and further to the transmission shaft 15 for seedling planting device A.
And a transmission system for transmitting power having the same rotational speed as the power from the engine 4 to the second power take-out shaft 40A on the rear surface of the transmission case via the sixth shaft 40. In addition, a gear-type inter-stock transmission mechanism 41 is provided between the third shaft 37 and the fourth shaft 38 for adjusting the planting interval of the seedlings in the running direction with respect to the field scene. A jump clutch 42 for interrupting transmission when an overload is applied from the device A is provided, and the fifth shaft 39 is provided with the planting clutch C.

As shown in FIG. 5, the third shaft 37 and the fifth shaft 3
9, the lubricating oil level L inside the transmission case 6 is set up to the lower position of the gear formed at
By forming an oil guide portion 43 on the inner surface of the transmission case 6 that reaches the inner peripheral surface of the shaft 37 and the fifth shaft 39 at a position close to the outer periphery of the gear, the third shaft 37 and the fifth shaft during transmission. By the rotation of the gear formed at 39, the lubricating oil can be sucked up in a gear motor type and supplied to the height of the uppermost fourth shaft 38. The power from the differential mechanism 35 to the rear wheels 2 is transmitted to the rear wheels 2 via the rear axle case 7.

As shown in FIG. 8, the continuously variable transmission 5 includes a variable displacement hydraulic pump P, a hydraulic motor M driven by the supply of hydraulic oil from the hydraulic pump P, and a hydraulic pump P. P1 and a hydraulic motor M, a first oil passage D1
And a second oil passage D2 to form a pair of oil passages, and is configured as a hydrostatic type. The hydraulic pump P is configured as an axial plunger type (not shown) that switches the discharge direction of the hydraulic oil and adjusts the discharge amount by adjusting the swash plate angle. The hydraulic motor M is supplied from the hydraulic pump P. The rotation direction is determined by the supplied hydraulic oil supply direction, and the rotational speed is set by the supply amount of hydraulic oil (not shown). When the body 3 is advanced by the driving force of the continuously variable transmission 5, the hydraulic oil from the hydraulic pump P is sent to the hydraulic motor M via the first oil passage D1, and is also transmitted via the second oil passage D2. Return to the hydraulic pump P, and
To reverse the hydraulic oil from the hydraulic motor M
The flow direction of the working oil is set so as to be sent to the hydraulic motor M side via the oil passage D2 and returned to the hydraulic pump P via the first oil passage D1, and the engine 4 is provided in these oil passages D1 and D2.
And a system for supplying hydraulic oil from the charge pump 46 driven by the first oil passage D1 to the other oil passage when the pressure in one of the first oil passage D1 and the second oil passage D2 increases. Relief valves 48, 48 for releasing pressure, and second oil passage D
2 is switched by the pilot pressure from the pilot oil passage 49P so as to open when the pressure drops in the second oil passage, and to close when the pressure in the second oil passage D2 rises, and to reduce the pressure in the second oil passage D2 during the opening operation. And a neutral valve 49 for releasing the air to the engine. The operating means K according to claim 1 is connected to the pilot oil passage 49P.
Is configured.

As shown in FIGS. 6 and 7, on the side surface of the continuously variable transmission 5, a trunnion shaft 50 for adjusting the amount of hydraulic oil from the hydraulic pump P by adjusting the swash plate angle, and the trunnion shaft 5
And a neutral urging mechanism B for returning the speed adjusting lever 51 provided to the neutral position to a neutral position. An electric transmission motor 52 is provided at these rear positions, and is engaged with a pinion gear 52A of the transmission motor 52. A sector gear 53 is swingably provided around a support shaft 54 having a horizontal shaft.
And a potentiometer-type shift sensor 56 that measures the shift state of the continuously variable transmission 5 on the axis and the coaxial axis of the sector gear 53 by linking the arm portion 53A and the speed control lever 51 formed through the rod 55. I have. Also, neutral biasing mechanism B
The roller 58 rotates freely on a return lever 57 that swings integrally with the trunnion shaft 50, and the cam member 59 formed with a cam surface 59A for restoring the return lever 57 to a neutral position by contact with the roller 58 is turned sideways. A return spring 61 is provided that is swingably supported by the support shaft 60 in the posture and that applies a biasing force to the side where the cam surface 59A contacts the roller.

As shown in FIG. 9, a lever sensor 62 is provided at the base end of the main transmission lever 13 to measure the transmission position of the main transmission lever 13.
And a control device 63 for controlling the speed change motor 52 based on the signals from the control device 6 and the speed change control system. The control device 63 includes a microprocessor (not shown), and moves the main shift lever 13 from the neutral position N to the forward range F.
When the shift operation is performed to the reverse region R, the lever sensor 62
When the program for driving the speed change motor 52 to perform the speed change control is set until the setting signal value measured in step S and the signal value from the speed change sensor 56 are balanced, and the main speed change lever 13 is set to the neutral position N, Is set to operate the speed control lever 51 to the neutral posture by the same control.

When the speed control lever 51 is in the neutral position N, the mechanical linkage is set so that the hydraulic oil from the hydraulic pump P is very slightly sent out to the second oil passage D2. When the speed change lever 13 is at the neutral position N, the neutral valve 49 is opened according to a decrease in the pressure of the second oil passage D2. As a result, the pressure of the second oil passage D2 is released to the drain oil passage T and the body 3 When the main shift lever 13 is operated forward from this stopped state, the supply amount of the hydraulic oil from the hydraulic pump P to the hydraulic motor M is gradually reduced from the almost zero state. By increasing the speed, a smooth speed increase can be performed without generating a shock.
When the supply amount of hydraulic oil with respect to the operation position of the main transmission lever 13 is graphed, as shown in FIG.
When the third gear 3 is operated from the neutral position N to the reverse side of the fuselage, an increased amount of hydraulic oil is supplied when the predetermined amount is operated as in the conventional example, but the main shift lever 13 is moved to the neutral position N.
When it is operated from the front to the forward side of the fuselage, the hydraulic oil is smoothly increased to enable a forward movement at a very low speed without generating a shock.

As described above, in the present invention, the single neutral valve 49 is used.
Is provided in the second oil passage D2 on the reverse side so that the discharge amount of hydraulic oil from the hydraulic pump P is reduced to zero when the speed adjusting lever 51 is set to the neutral position by the urging force from the neutral urging mechanism B. The reverse side, that is, the hydraulic pump P
The movement of the fuselage 3 can be completely stopped by adjusting the hydraulic fluid to flow to the side of the second oil passage D2 slightly, and the main shift lever 13 is operated from the neutral position N toward the forward range F. In this case, the closing operation of the neutral valve 49 is delayed, and the drive of the hydraulic motor M can be started even in the open state, so that the hydraulic oil for the forward side, that is, the side of the first oil passage D1 is interlocked with the operation of the lever 13. Smoothly increase the supply of air to enable smooth acceleration, and even if the work is performed by moving the body 3 solely from the stopped state like a rice transplanter and performing work, smooth work at the start of traveling and comfortable work Is made possible. It should be noted that the hydraulic pump P
When the supply of the hydraulic oil to the hydraulic motor M side is started, the hydraulic oil is returned from the hydraulic motor M to the hydraulic pump P at least in the open position of the neutral valve 49 by the action of the orifice in the valve. However, since the amount of hydraulic oil returned is greatly reduced, hydraulic oil is supplied to the second oil passage D2 from the charge pump 46, and the amount of hydraulic oil delivered from the hydraulic pump P is not reduced. I have.

[Other Embodiments] In addition to the above-described embodiment, the present invention is applied to a case where the neutral valve 49 is constituted by an electromagnetic valve and the shift setting system is set to the neutral position N as shown in FIG. It is also possible to cooperate with the control device 63 so as to be electrically operated to the open position and to be electrically closed when operated from the neutral position N in the speed increasing direction. In this configuration, the operating means K is constituted by a signal system for controlling the neutral valve 49 from the control device 63. It is to be noted that, in another embodiment having the same function as that of the above embodiment, the same number and reference numeral as those of the embodiment are given.

Further, in the present invention, the speed change operation tool and the neutral valve can be mechanically linked, and the hydraulic pump can be controlled by manual operation force.

[0026]

Accordingly, when the shift operation tool is set to the neutral position, the phenomenon that the body moves at a very low speed is prevented, and when the body is advanced from the stopped state, the body is smoothly moved without generating a shock. The continuously variable transmission capable of starting the vehicle is rationally configured (claim 1). Further, by configuring the neutral valve as a hydraulically operated type, a system for opening and closing the neutral valve can be made compact and simple (Claim 2). The operation tool and the neutral valve are accurately linked to each other to reliably prevent the body from moving when the shift operation tool is in the neutral position, and to be large when the shift operation tool is operated from the neutral position to the reverse side. This allows the aircraft to move backward without manipulating the stroke (claim 3).

[Brief description of the drawings]

FIG. 1 is an overall side view of a rice transplanter.

FIG. 2 is a side view of a transmission system.

FIG. 3 is an exploded perspective view of a joint portion of a third intermediate shaft.

FIG. 4 is a diagram showing a transmission system of a transmission case.

FIG. 5 is a longitudinal sectional view of a transmission case.

FIG. 6 is a side view of an operation system of the continuously variable transmission.

FIG. 7 is a side view showing details of an operation system of the continuously variable transmission.

FIG. 8 is a hydraulic circuit diagram of the continuously variable transmission.

FIG. 9 is a block circuit diagram of a shift control system.

FIG. 10 is a graph showing a supply amount of hydraulic oil with respect to an operation amount of a main shift lever.

FIG. 11 is a hydraulic circuit diagram showing another embodiment of the continuously variable transmission.

[Explanation of symbols]

 Reference Signs List 4 engine 13 shift operation tool 49 neutral valve 56 potentiometer 63 control device D1 first oil passage D2 second oil passage K operating means M hydraulic motor P hydraulic pump N neutral position F forward area R reverse area

Claims (3)

[Claims] 1. A variable displacement hydraulic pump driven by an engine, a hydraulic motor that converts hydraulic oil supplied from the hydraulic pump into rotational force and transmits the rotational force to a traveling system, and a hydraulic pump and a hydraulic motor. A first oil passage for body advance formed at the second position, a second oil passage for body backward formed between the hydraulic pump and the hydraulic motor, and a shift operation tool for controlling the hydraulic pump. The greater the operating device is operated from the neutral position to the forward region, the greater the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic motor via the first oil passage, and the larger the operating device of the shift operating device is shifted from the neutral position to the reverse region. When the amount of hydraulic oil supplied from the hydraulic pump to the hydraulic motor via the second oil passage is increased and the shift operation tool is set to the neutral position, the first
A continuously variable transmission for a working machine in which the shift operation tool and a hydraulic pump are linked so as to minimize the supply amount of hydraulic oil to each of an oil passage and a second oil passage, wherein the shift operation tool is neutral. A continuously variable transmission for a working machine comprising a neutral valve for releasing the pressure of the second oil passage to the drain oil passage by an opening operation by the operation of the operating means when set to the position. 2. The operation means directly acts on the neutral valve so as to open the neutral valve as the pressure in the second oil passage decreases and close the neutral valve as the pressure in the second oil passage rises. The continuously variable transmission for a working machine according to claim 1, wherein the transmission is constituted by a pilot oil passage. 3. The shift setting system includes a potentiometer for measuring a shift set position, the neutral valve is configured to be an electromagnetically operated type, and the shift means is set to a neutral position based on a signal from the potentiometer. 2. The continuously variable transmission according to claim 1, further comprising a control system for operating the neutral valve to the open position when it is determined that the neutral valve is present.