JPH0826848B2 - Hydraulic control mechanism of variable displacement pump in industrial vehicle - Google Patents

Description

TECHNICAL FIELD The present invention relates to a hydraulic control mechanism for a variable displacement pump in an industrial vehicle.

[Conventional technology]

The skid steer system industrial vehicle includes a drive unit as shown in FIG. That is, a pair of hydraulic motors 53, 54 are provided corresponding to the front and rear wheels 51, 52 respectively provided on the left and right sides of the vehicle 50, and the variable displacement oil pump 56 is started when the engine 55 is started.
The motor oil is discharged by the motors 53 and 54, and this rotation is transmitted to the wheels 51 and 52 via the chain sprocket mechanisms 57 and 58.

Then, as shown in FIG. 6, a pair of steering levers 59 (only one is shown) are provided corresponding to the respective motors 53, 54, and by operating these levers 59 back and forth as indicated by the chain double-dashed line. Pump through the steering rod 60
The trunnion lever 61 provided on the outer wall of 56 is rotated to change the swash plate angle of the pump 56. This allows the motors 53,54
The rotation direction of the vehicle changes, and the vehicle 50 moves forward and backward.

When the steering lever 59 is released and the operation is stopped, the trunnion lever 61 is biased by the spring S in the spring holder 62, so that the steering lever 59 is held at the neutral position as shown by the solid line. The vehicle 50 is stopped.

When the discharge pressure of the pump 56 changes abruptly, the rotation of the motors 53, 54, that is, the wheels 51, 52 also changes abruptly, and the impact causes the wheels 51, 52 to jump up, causing the vehicle 50 to be in an unstable state. Drive in. Therefore, both trunnion levers 61
Are connected by a damper member 63 composed of a hydraulic cylinder, and the cylinder rod 63a of the damper member 63 urges both trunnion levers 61 in the upright direction, so that the trunnion lever 61 acts on the side opposite to the rotation direction. It gives power. Even if the driver suddenly changes the posture of the steering lever 59, the trunnion lever 61 is slowly rotated by the strong resistance force of the damper member 63 applied to the trunnion lever 61, and the discharge pressure of the pump 56 is increased. The rapid change of the vehicle is avoided, and the safe driving of the vehicle 50 is realized.

[Problems to be Solved by the Invention]

However, the damper member 63 described above is assembled in a complicated link mechanism including the steering rod 60, the trunnion lever 61, and the spring holder 62, and manufacturing and maintenance management are complicated.

Furthermore, every time the steering lever 59 is operated,
As the trunnion lever 61 rotates, the damper member 63 expands and contracts, the mounting portions of the both 61, 63 are severely worn, and the service life is significantly shortened.

In addition, the steering lever 59
However, the force of the damper member 63 that opposes the steering operation is set to a constant value, and an accurate cushioning effect according to the steering operation cannot be obtained.

The present invention has been made to solve the above-mentioned problems, and a first object thereof is to provide an industrial vehicle capable of obtaining a cushioning effect accurately corresponding to a steering operation by arbitrarily setting a damper force. To provide a hydraulic control mechanism for a variable displacement pump. A second object is to provide a hydraulic control mechanism for a variable displacement pump in an industrial vehicle which is easy to manufacture and maintain and has a long service life in addition to the first object.

[Means for solving the problem]

In order to achieve the above-mentioned first object, the present invention changes the inclination direction by operating the operating means for changing the traveling direction of the vehicle and stopping the traveling, and controls the rotation of the drive wheels based on the inclination. A swash plate for stopping and rotating the hydraulic motor forward and backward is installed in the hydraulic oil storage chamber in which the hydraulic oil in the pump is full, and a sudden change in the inclination of the swash plate is prevented to discharge the hydraulic motor. In a variable displacement pump for an industrial vehicle, which is provided with a regulating means for regulating a sudden increase in the pressure of the hydraulic oil, the regulating means is provided with a branch passage branched from the hydraulic oil accommodating chamber and a posture change of the swash plate. And a forcibly moving member that reciprocates in the branch passage to forcibly move the working oil flowing into the branch passage from the hydraulic oil storage chamber, and variably adjusts the flow passage cross-sectional area of the working oil in the branch passage. Through the forced movement member The adjustment amount to perform the slow slope changes according to its gist that the operation of the operating means is constituted by a flow control member for causing at any speed. The flow rate control member is composed of, for example, an adjusting screw capable of adjusting the amount of protrusion into the branch passage.

Further, in order to achieve the second object, the branch passage, the forced moving member and the flow rate controlling member which constitute the regulating means are provided inside the pump, and only the portion of the flow rate controlling member necessary for adjustment is provided outside the pump. The point is that it is exposed.

[Action]

By adopting the above means, the forced movement member moves in the branch passage as the inclination angle of the swash plate is changed by the operation of the operating means, and the hydraulic oil in the branch passage is forcibly moved. However, since the fluid flow cross-sectional area of the hydraulic oil is adjusted by the flow rate control member, the resistance of the hydraulic oil is added to the forced movement member, and the forced movement member moves slowly. Therefore, the inclination angle of the swash plate is slowly changed, and a sudden operation of the operating means becomes impossible.

Further, the fluid cross-sectional area of the hydraulic oil is variably adjusted by the flow rate control member, and the resistance of the hydraulic oil applied to the forcibly moving member is changed according to this, whereby the operating means can be operated at an arbitrary speed. Becomes

Further, by providing the branch passage, the forced movement member, and the flow rate control member, which constitute the regulating means, inside the pump, manufacturing and maintenance management of the pump provided with the regulating means are facilitated and the service life is extended.

〔Example〕

Hereinafter, one embodiment in which the present invention is embodied as a hydraulic pressure sudden increase control mechanism for a variable displacement pump in a shovel loader will be described.
It will be described in detail according to FIG.

In FIG. 1, the variable displacement pump 1 is an oil tank T.
Is arranged side by side with the oil pump O connected to
It is composed of a front pump 3 and a rear pump 3a with a port block 2 communicating with the oil pump O and the motors M and Ma sandwiched therebetween, and is driven by starting the engine E. The front pump 3 and the rear pump 3a are respectively operated by steering levers L and La as a pair of operating means arranged on the left and right of the vehicle B, and left and right via a chain sprocket mechanism C and Ca by rotation of corresponding motors M and Ma. The wheels W and Wa of are rotated separately.

As shown in FIG. 2, a cylinder block 5 is arranged in the pump housing 4 of the front pump 3, and a storage chamber 6 filled with hydraulic oil is provided in the space between the outer peripheral wall of the cylinder block 5 and the inner wall of the housing 4. Has been formed. Further, on the right end surface of the cylinder block 5, nine hydraulic pressure adjusting holes 7 and 32 (only the upper and lower two are shown) are formed at equal intervals in the inner circumferential direction, and further, the left end surface of the cylinder block 5 and the port block 2 are formed. A communication passage 8 formed between the storage chamber 6 and the adjustment hole 7 is formed between the storage chamber 6 and the right end recess 33. The communication passage 8 is 2
The kidneys 9 and 10 (Fig. 3) are in communication with each other, and the forward and backward movements of the steering lever L selectively switch the functions of discharging and sucking the hydraulic oil of these kidneys 9 and 10, and the neutral operation. Both kidneys 9 and 10 are cut off from the motor M.

In addition, due to an oil supply path (not shown) formed in the port block 2, when the vehicle B moves forward, the hydraulic oil is supplied to the kidney 10.
And is supplied to the motor M. Then, the hydraulic oil returned from the motor M that rotates in the normal direction is sucked from the kidney 9 and this operation is repeated.

Further, the cylinder block 5 extends horizontally through the central portions of the cylinder block 5 and the port block 2 and is spline-coupled to the drive shaft 11 that rotates by the operation of the engine E, and a spring holding hole formed in the cylinder block 5 is formed. H
A pulling spring 19 is installed between a fixed plate 17 fixed on the outer peripheral surface of the left end of the drive shaft 11 and a sliding plate 18 slidably mounted on the outer peripheral surface of the right end of the drive shaft 11. 11 The cylinder block 5 is restricted from moving to the left beyond the predetermined amount on the upper side.

A movable swash plate 20 having a substantially disc shape is provided on the right side of the cylinder block 5, and as shown in FIG. 3, a trunnion shaft protruding above an annular portion 21 provided on the outer peripheral surface thereof.
A central portion of the trunnion lever 23 is fixed to the 22.
The upper end of the trunnion lever 23 is connected to the steering rod 24. Then, based on the tilting operation of the steering lever L, the trunnion lever 23 is tilted via the steering rod 24 connected to the lower end of the steering lever L, and the swash plate 20 is tilted left and right around the trunnion shaft 22 or is made to stand upright. It is designed to change the posture. As shown in FIG. 2, a through hole 25 having a diameter larger than that of the drive shaft 11 is provided at the center of the swash plate 20, and the drive shaft 11 passing through the through hole 25 has a bearing at the end of the housing 4. It is rotatably supported at 26.

Further, a thrust plate 12 is arranged adjacent to the left side of the swash plate 20, the drive shaft 11 is loosely fitted in a through hole 34 of the swash plate 20, and the thrust plate 12 is tilted with the swash plate 20.
Is tilted. Nine piston bodies 13 and 35 are attached at equal intervals over the entire circumference of the thrust plate 12. The piston bodies 13 and 35 are thrust plates 12
The short cylindrical mounting parts 14 and 36 fixed to the left surface of the cylinder block, the small diameter flexible parts 15 and 37 projecting leftward from the mounting parts and the adjustment holes 7 and 32 of the cylinder block 5 It is composed of cylindrical pressure adjusting portions 16 and 38 which are in sliding contact with the inner peripheral wall.

A branch passage 27 extending from the accommodating chamber 6 is formed in a substantially U-shape in the upper part of the inner wall of the front part of the housing 4, and the working oil flows in from an opening 28 at one end thereof. Further, the other end of the branch path 27 is closed by a sliding piece 30 which is connected to the swash plate 20 via a connecting node 29 as a forced moving member.
Further, an adjusting screw 31 as a flow rate regulating member screwed from the outside of the housing 4 projects at a corner of the branch passage 27, and a throttle portion 39 is formed between the projecting end and the inner wall of the branch passage 27. . The hydraulic oil that is forcibly moved in the branch passage 27 by the sliding piece 30 that moves with the inclination of the swash plate 20 is
The moving speed is controlled by the interval of the narrowed portions 39 determined by the protrusion amount of 31. The branch passage 27, the sliding piece 30 and the adjusting screw 31 constitute a regulating means.

Further, the rear pump 3a located on the left side also has the same configuration as the front pump 3, and the components corresponding to the above-described components are shown by attaching the same reference numerals with a in the drawings.

The drive shaft 11 is rotated by the engine E, and the variable displacement pump 1 is held in the state shown in FIG. 1 when both steering levers are in the neutral position. That is, the swash plate
20 and 20a are in the upright posture, and the thrust plates 12 and 12a are also upright. In this state, the adjustment holes 7,
Each piston body 13,35 and 13a, 35a in 32 and 7a, 32a
The positions are the same, and the pressure in these adjusting holes 7, 32 and 7a, 32a is kept constant. Therefore, the hydraulic oil is not sucked or discharged by each of the kidneys 9, 10 and 9a, 10a, the left and right motors M, Ma are stopped and held, the vehicle B does not run, and the idling state Held in.

Next, the operation of moving the vehicle B forward will be described with reference to FIG. Although only the front pump 3 will be described here, the rear pump 3a also performs the same operation. When the steering lever L is moved to the forward position when the drive shaft 11 rotates, the trunnion lever 23 is rotated counterclockwise via the steering rod 24, and the swash plate 20 is rotated counterclockwise via the trunnion shaft 22. Be moved. Along with this, the thrust plate 12 rotates in the same direction, so that the mounting portion 14 of the upper piston body 13 is moved to the left. Therefore, a force for pressing the adjusting portion 16 via the flexible portion 15 is applied, and the flexible portion 15 is curved by this force, and the adjusting portion 16
Is moved to the left in the adjustment hole 7 of the cylinder block 5. As a result, the hydraulic oil in the adjustment hole 7 of the cylinder block 5 is squeezed out to the communication passage 8. As described above, the storage chamber 6
Since the inside is filled with hydraulic oil, the hydraulic oil that has been squeezed out into the communication passage 8 flows into the motor M through the kidney 10.

Further, the mounting portion 36 of the piston body 35 located below is moved to the right by the thrust plate 12, and the adjusting portion 38 moves to the right in the adjusting hole 32 of the cylinder block 5. For this reason,
Negative pressure is generated in the adjusting hole 32 of the cylinder block 5, and hydraulic oil flows in. Then, as the drive shaft 11 rotates, the cylinder block 5 rotates together with the thrust plate 12, and when the piston bodies 13 and 35 and the cylinder block 5 are turned upside down, the adjusting portion 38 of the piston body 35 moves to the left. Then, the hydraulic oil is discharged from the adjustment hole 32 of the cylinder block 5. Then, this hydraulic oil is discharged from the kidney 10, and the motor M
To rotate the vehicle forward to move the vehicle B forward.

As described above, the steering lever L is operated to operate the swash plate.
When turning 20 clockwise, connect the joints with the swash plate 20.
The sliding piece 30 is pulled via 29 and tries to move to the left in the branch path 27. With the movement of the sliding piece 30, a negative pressure is generated in the branch passage 27, and the hydraulic oil flows from the accommodation chamber 6 into the branch passage 27. This hydraulic oil is passed through the branch passage 27 to the throttle portion 39.
Due to this, since the passage cross-section is limited and the inside of the branch passage 27 is filled, the movement of the sliding piece 30 and the swash plate 20 becomes slow.

Therefore, a strong force acting in the direction opposite to the operation direction is also applied to the steering lever L that rotates the swash plate 20, and it becomes impossible to rapidly operate the steering lever L. That is, the driver operates the steering lever L
Is forced to operate slowly, which causes the motor M to gradually reverse and stop. Therefore, abrupt conversion of the traveling direction of the vehicle B and traveling stop are prevented.

When it is desired to move the vehicle B backward, the steering lever L is changed to the backward posture, and the swash plate 20 and the piston body 1 are moved.
The motors 3, 35 reverse the motor M by the reverse operation.

In the above configuration, the amount of adjustment screw 31 screwed into housing 4 can be changed to change the amount of reduction of throttle portion 39. Therefore, the resistance force when the steering lever L is operated can be set according to the driver's arm force.

It should be noted that the present invention is not limited to the above-described embodiments, and any modifications can of course be made without departing from the spirit of the present invention, such as being adopted in an industrial vehicle other than a shovel loader.

〔The invention's effect〕

As described in detail above, according to the first aspect of the present invention, by setting the damper force arbitrarily, it is possible to obtain a cushioning effect that accurately corresponds to the steering operation. In addition, the maintenance is simple and the service life is long.

[Brief description of drawings]

1 is a schematic plan view showing a skid steer type shovel loader using the hydraulic control device of the present invention, FIG. 2 is a sectional view showing a variable displacement pump, and FIG. 3 is a front pump of the variable displacement pump. FIG. 4 is a perspective view, FIG. 4 is a cross-sectional view showing the front pump when the vehicle is moving forward, and FIGS. 5 and 6 are a schematic plan view and a schematic side view showing a conventional example, respectively. Operating means L, La, drive wheels W, Wa, motors M, Ma, swash plates 20, 20a,
Branch paths 27, 27a, sliding pieces 30, 30a, and adjusting screws 31, 31a as flow rate control members (the branching path, the sliding pieces, and the adjusting screws described above constitute a regulating means).

Claims (3)

[Claims] 1. A tilt direction in which a tilt direction is changed by operating an operating means for instructing a change of a running direction of a vehicle and a stop of running, and a hydraulic motor for controlling a rotation of a driving wheel based on the tilt is rotated forward and backward and stopped. The plate is arranged in the hydraulic oil storage chamber in which the hydraulic oil in the pump is full, and the sudden change of the inclination of the swash plate is prevented to prevent a sudden increase in the pressure of the hydraulic oil discharged to the hydraulic motor. In a variable displacement pump for an industrial vehicle equipped with a regulation means, the regulation means reciprocates in a branch passage branched from the hydraulic oil storage chamber and in the branch passage with a change in the posture of the swash plate, A forcibly moving member for forcibly moving the working oil that has flowed into the branch passage from the working oil storage chamber, and variably adjusting the flow passage cross-sectional area of the working oil in the branch passage,
The hydraulic pressure of the variable displacement pump in the industrial vehicle constituted by the flow rate control member that causes the swash plate to slowly change the inclination according to the adjustment amount through the forced movement member and allows the operation means to operate at an arbitrary speed. Control mechanism. 2. The hydraulic control mechanism for a variable displacement pump in an industrial vehicle according to claim 1, wherein the flow rate control member is an adjusting screw capable of adjusting the amount of protrusion into the branch passage. 3. A branch passage, a forcibly moving member and a flow rate controlling member which constitute the regulating means are provided inside the pump, and only a portion of the flow rate controlling member necessary for adjustment is exposed to the outside of the pump. A hydraulic control mechanism for a variable displacement pump in the industrial vehicle described.