JP2002031038A - Hydraulic power unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hydraulic power unit miniaturized while ensuring the necessary performance of a spring for allowing a switching valve to be constantly abutted on a switching valve engagement member. SOLUTION: A first valve hole 53 and a second valve hole 54 are formed on a cylinder block 25 with an input shaft 15 inserted therein, and a first switching valve 56 and a second switching valve 66 are mounted in the first and second valve holes. A pressuring chamber 53a is formed on the right of the first valve hole 53, and a pressurizing chamber 54a is formed on the left of the second valve hole 54. Coil springs 57 and 67 are mounted in the pressuring chambers 53a and 54a. An oil passage 74, an oil passage 73 and a circumferential groove 72 are formed on a case 11, an introductory oil passage 71, a shaft hole 70 and an oil passage 77 are formed on the input shaft 15, and a circumferential groove 78 is formed on the cylinder block 25. The hydraulic oil flows into the oil passage 74 from a charging pump to fill the pressurizing chambers 53a and 54a with the hydraulic oil. The switching valves 56 and 66 are energized by the oil pressure of the hydraulic oil in the pressurizing chamber 53a and 54a and the coil springs 57 and 67.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a hydraulic device which can be widely used in various industrial fields such as industrial machines and vehicles.

[0002]

2. Description of the Related Art Conventionally, a swash plate type hydraulic device has been known as a hydraulic device. The following is an example of a swash plate type hydraulic device. This swash plate type hydraulic device includes a cylinder block, a plunger group, a plunger swash plate, a yoke, an output shaft, a slide spool valve group, and a valve swash plate.
A plunger group is arranged in the cylinder hole group of the cylinder block. A slide spool valve group is arranged in a valve hole group of the cylinder block, and a hydraulic circuit connecting each cylinder hole to each valve hole is formed in the cylinder block.

[0003] When hydraulic oil is sucked and discharged into each cylinder hole, rotation is given to the plunger swash plate and the yoke via a shoe provided at one end of the plunger group. The tip of each slide spool valve protrudes from the cylinder block, and a spring is wound around each of the slide spool valves so that the tip surface of each slide spool valve always contacts the valve swash plate.

[0004]

However, in the swash plate type hydraulic device, it is necessary to provide a spring so that the leading end surface of the slide spool valve always contacts the valve swash plate. In order to maintain the strength (durability) against a load, there is a problem that the spring must be very large.

Accordingly, the present invention has been made in view of the above-mentioned circumstances, and has as its object to eliminate the need for a spring itself or to reduce the size of a slide spool valve even if the spring is small and has a small spring constant. It is an object of the present invention to provide a hydraulic device capable of reliably contacting a front end surface with a valve swash plate.

[0006]

In order to achieve the above object, an invention according to claim 1 comprises a cylinder block for accommodating a plunger, a hydraulic circuit communicating with a cylinder hole for accommodating the plunger, and a cylinder hole. A switching valve for selectively communicating with the first oil chamber or the second oil chamber provided in the hydraulic circuit;
In a hydraulic device having a switching valve engagement member for reciprocating a switching valve, a gist is provided in which a pressure applying chamber for pressing the switching valve against the switching valve engagement member by the hydraulic pressure of hydraulic oil is provided.

According to a second aspect of the present invention, in the first aspect, a spring for pressing the switching valve to the switching valve engaging member is further provided in the pressure applying chamber. (Operation) Therefore, in the first aspect of the present invention, the switching valve is pressed by the switching valve engaging member by the pressure of the hydraulic oil in the pressure applying chamber.

[0008] In the invention described in claim 2, in addition to the operation described in claim 1, the switching valve is configured to control the hydraulic pressure of the working oil in the pressure application chamber and the urging force of the spring provided in the pressure application chamber. It is pressed by the switching valve engagement member by cooperation.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is embodied in a hydraulic device will be described below in detail with reference to FIGS.

As shown in FIGS. 1 to 4, a case 11 of the hydraulic device T has a substantially cylindrical main body case 12 which is open on one side.
And a lid 13 fixed to the opening of the main body case 12.
It is composed of A holder 14 is inserted and fixed in a through hole 13 a provided in the lid 13. One end of the input shaft 15 of the hydraulic device T is rotatably supported on the holder 14 via a conical roller bearing 16, and the other end is conical with a yoke 38 provided on the other end side in the main body case 12. It is rotatably supported via a roller bearing 41,
It is a PTO axis. The yoke 38 is the main body case 1
The other end is rotatably supported via a radial bearing 17.

The holder 14 has a through hole 14a through which the input shaft 15 passes. The input side of the through hole 14a is enlarged in diameter to form a seal member storage hole 18, and a seal member 19 is disposed in the seal member storage hole 18. The output side of the through hole 14a is also enlarged in diameter to form a bearing housing hole 20. The inner ring 16a of the conical roller bearing 16 is fitted and fixed to the input shaft 15, and the outer ring 16b is fixedly abutted on the bottom surface and the peripheral surface of the stepped portion of the bearing housing hole 20 whose diameter is increased.

A sleeve 21 is inserted through the input shaft 15 near the output side of the inner ring 16a, and the input side surface of the sleeve 21 is in contact with the inner ring 16a. Also,
The output side surface of the sleeve 21 is in contact with the input side surface of a cylinder block 25 described later. The bearing receiving hole 2
A bearing mounting step 22 (see FIG. 3) having a diameter larger than that of the bearing housing hole 20 is formed in the opening 0, and a radial bearing 23 is mounted on the bearing mounting step 22.

The radial bearing 23 has an outer ring 23a.
And an inner ring 23b as a switching valve engagement member. The outer ring 23a is fixedly abutted on the bottom surface and the peripheral surface of the stepped portion of the bearing mounting step 22 whose diameter is enlarged. As shown in FIG.
The radial bearing 23 is disposed so that its axis is inclined at a predetermined angle with respect to the axis O of the cylinder block 25 described later, and its inner ring 23b moves the first switching valve 56 described later in the direction of the axis O at a predetermined timing. It is a cam for sliding. The output side surface of the inner ring 23b is a cam surface 58.

The hydraulic pump P includes an input shaft 15 and a cylinder block 25 provided integrally with the input shaft 15.
And a plurality of plungers 26 slidably disposed on the cylinder block 25, and a cradle 28 including a swash plate surface 27 that comes into contact with the plungers 26.

The cradle 28 can be tilted about a trunnion axis TR1 (see FIG. 3) orthogonal to the axis O of the cylinder block 25. On the input side of the cylinder block 25, the cylinder block 25 is spline-coupled to the input shaft 15.
The output side surface of the cylinder block 25 is in contact with a locking flange 15 a provided on the outer periphery of the input shaft 15.
In the cylinder block 25, a plurality of cylinder holes 29 are annularly arranged around the center of rotation, and extend in parallel with the axis O. The cylinder hole 29 has an opening formed on the input side. The plunger 2 is provided in each cylinder hole 29.
6 are slidably disposed.

A steel ball 26a is rotatably fitted to the tip of the plunger 26.
a and a swash plate surface 27 via a shoe 30 to which a steel ball 26a is attached. The swash plate surface 27 in the inclined state reciprocates the plunger 26 with the rotation of the cylinder block 25, and gives an effect of a suction and discharge stroke.

The hydraulic motor M is connected to the cylinder block 2
5 includes a plurality of plungers 36 slidably disposed therein and a substantially trumpet-shaped yoke 38 having a rotating swash plate surface 37 that comes into contact with the plungers 36.

As shown in FIG. 4, on the inner periphery of the yoke 38, there are provided three enlarged diameter portions 38a, 38b and 38c whose diameters increase in order from the output side to the input side. A seal member 40 is disposed on the enlarged diameter portion 38a,
A conical roller bearing 41 is disposed on the enlarged diameter portion 38b.
The inner ring 41 a of the conical roller bearing 41 is fitted and fixed to the input shaft 15, and its input side surface is in contact with the end of the enlarged diameter portion of the input shaft 15. Also, the outer ring 41b of the conical roller bearing 41
Is fixedly abutted on the bottom surface and the peripheral surface of the enlarged step portion of the enlarged portion 38b.

A radial bearing 42 is provided on the enlarged diameter portion 38c.
Is arranged. The radial bearing 42 includes an outer ring 42a and an inner ring 42b as a switching valve engagement member, and the outer ring 42a is abutted and fixed to the stepped bottom surface and the peripheral surface of the enlarged diameter portion 38c. As shown in FIG.
The radial bearing 42 is disposed such that its axis is inclined at a fixed angle with respect to the axis O of the cylinder block 25, and its inner ring 42b is connected to a second switching valve 66 described later.
At a predetermined timing in the direction of the axis O. The input side surface of the inner ring 42b is a cam surface 6
It is 8.

A through hole 12a is formed at the other end of the main body case 12, and a reduced diameter portion 12b is provided at the other end of the through hole 12a. The reduced diameter portion 12b
A seal member 43 is disposed on the radial bearing 1 in the through hole 12a in order from the output side to the input side.
7, a sleeve 44 and a conical roller bearing 45 are arranged. The inner ring 17a of the radial bearing 17 is a yoke 38.
The outer ring 17b is fixed to the side of the reduced diameter portion 12b and the peripheral surface of the through hole 12a.

The sleeve 44 is fixed to the outer race 17b of the radial bearing 17 and the peripheral surface of the through hole 12a. The inner ring 45a of the conical roller bearing 45 is a yoke 3
The input side surface is in contact with the end of the enlarged diameter portion of the yoke 38. Outer ring 45 of conical roller bearing 45
b is fixed to the sleeve 44 and the peripheral surface of the through hole 12a.

The output end of the yoke 38 slightly protrudes from the other end of the main body case 12, and an output shaft 47 is formed. The rotary swash plate surface 37 is held by the yoke 38 at a predetermined angle with respect to the axis O about a virtual trunnion axis TR2 (see FIG. 4) orthogonal to the axis O of the cylinder block 25.

In the cylinder block 25, the same number of cylinder holes 39 as the cylinder holes 29 are arranged annularly around the center of rotation, and extend in parallel with the axis O. The cylinder hole 39 is arranged on the same circumference as the cylinder hole 29. The cylinder block 2 is positioned so that each cylinder hole 39 is located between the cylinder holes 29 adjacent to each other.
In the circumferential direction of No. 5, the cylinder hole 29 is シ リ ン ダ of each other.
They are arranged shifted by a pitch (see FIGS. 5 and 6).

Further, the cylinder hole 39 is provided in the cylinder hole 29.
2 are arranged so as to overlap each other in the length direction (the direction of the axis O of the cylinder block 25), and an opening is formed on the yoke 38 side as shown in FIG. A plunger 36 is slidably disposed in each cylinder hole 39, and a steel ball 36a is rotatably fitted to the tip of the plunger 36. The plunger 36 is in contact with the rotating swash plate surface 37 via a steel ball 36a and a shoe 48 to which the steel ball 36a is attached. The plunger 36 reciprocates with the relative rotation between the rotary swash plate surface 37 and the cylinder block 25, and repeats the receiving and discharging processes.

A hydraulic circuit formed between the hydraulic pump P and the hydraulic motor M will be described. An annular first oil chamber 51 and a second oil chamber 52 are formed on the inner peripheral surfaces of both ends in the axial direction of the cylinder block 25. The first oil chamber 51 and the second oil chamber 52 are provided in the cylinder block 25.
Are provided along the axial direction of the cylinder block 25 in the same number as the number of the cylinder holes 29. The first oil chamber 51 is provided in the cylinder block 25.
The same number of second valve holes 54 as the cylinder holes 39 extend in the axial direction of the cylinder block 25.

The first valve holes 53 and the second valve holes 54 are concentric with the pitch circles of the cylinder holes 29 and 39 and are arranged on a pitch circle having a diameter smaller than the pitch circle. I have. Each of the first valve holes 53 and each of the second valve holes 54 are arranged so as to be adjacent to each other as shown in FIGS.

As shown in FIGS. 1 and 7, each first valve hole 53 has a pump in an oil passage 55 communicating between the first oil chamber 51 and the second oil chamber 52 and the corresponding cylinder hole 29. Port U is formed.

In each first valve hole 53, a first switching valve 56 as a spool type switching valve is slidably disposed. A coil spring 57 as a spring is disposed between the base end surface of the first switching valve 56 and the bottom surface of the first valve hole 53. Hereinafter, the coil spring 5 in the first valve hole 53
The space where 7 is disposed is a pressure application chamber 53a. By the cooperation of the urging force of the coil spring 57 and the pressure of the hydraulic oil charged in the pressure applying chamber 53a described later, the tip of the first switching valve 56 always contacts the cam surface 58 of the inner ring 23b. Touched.

FIG. 7 shows a cam profile of the inner ring 23b of the radial bearing 23. As shown in the figure, the cam surface 58 of the inner ring 23b is connected to the pump port U and the first switching valve 56 around the port closed position n0.
A first opening position n1 for communicating with the oil chamber 51, and a second opening position n2 for communicating between the pump port U and the second oil chamber 52.
There are provided a region H and a region I which reciprocate between them so as to draw a sine curve.

As shown in FIG. 7, a plurality of plungers 26
Are located in the area H of the cam profile and any are located in the area I. And radial bearing 2
The suction stroke and the discharge stroke are given to the hydraulic pump P by the cam action of the third inner ring 23b.

In the present embodiment, as shown in FIGS.
When the cradle 28 is tilted counterclockwise with respect to the axis O, in the region H, the first switching valve 56 is moved to the first opening position n as the cylinder block 25 rotates.
1 to bring the pump port U into communication with the first oil chamber 51 and to be in a non-communication state with the second oil chamber 52. In the region H, the operating oil is sucked into the cylinder hole 29 through the first oil chamber 51, the pump port U, and the oil passage 55 by the plunger 26 performing the suction operation.

In the region I, the first switching valve 56 is moved to the second opening position n as the cylinder block 25 rotates.
2 so that the pump port U communicates with the second oil chamber 52 and the pump port U is disconnected from the first oil chamber 51. In the region I, the hydraulic oil is discharged from the cylinder hole 29 to the second oil chamber 52 through the oil passage 55 and the pump port U by the plunger 26 that performs the discharging operation.

When the cradle 28 is tilted clockwise with respect to the axis O, the hydraulic oil is discharged from the cylinder hole 29 to the first oil chamber 51 through the oil passage 55 and the pump port U in the region H. You. At this time, in the region I, the hydraulic oil is sucked into the cylinder hole 29 via the second oil chamber 52, the pump port U, and the oil passage 55.

As shown in FIGS. 1 and 7, each second valve hole 54 has a motor in an oil passage 65 communicating between the first oil chamber 51 and the second oil chamber 52 and the corresponding cylinder hole 39. A port W is formed.

In each second valve hole 54, a second switching valve 66 as a spool type switching valve is slidably disposed so as to be parallel to the plunger 36. A coil spring 67 as a spring is arranged between the base end surface of the second switching valve 66 and the bottom surface of the second valve hole 54. Hereinafter, the space in which the coil spring 67 is disposed in the second valve hole 54 is referred to as a pressure applying chamber 54a. The urging force of the coil spring 67 and the pressure applying chamber 54 described later
The tip of the second switching valve 66 is always in contact with the cam surface 68 of the inner ring 42b in cooperation with the pressure of the working oil charged in the inner ring 42b.

FIG. 7 shows a cam profile of the inner ring 42b of the radial bearing 42. As shown in the drawing, the cam surface 68 of the inner ring 42b is connected to the motor port W and the second switching valve 66 around the port closing position m0.
A first opening position m1 for communicating with the oil chamber 52, and a second opening position m2 for communicating between the motor port W and the first oil chamber 51.
An area J and an area K are provided so as to reciprocate between them so as to draw a sine curve.

As shown in FIG.
Are located in the area J of the cam profile and any are located in the area K. Note that, in FIG.
The relative position between the cam bearing surface 8 and the cam surface 68 changes due to the rotation of the radial bearing 42 together with the yoke 38 (see FIG. 3), but they are shown together for convenience of explanation.

Then, with the relative rotation of the cylinder block 25, a receiving stroke and a discharging stroke are given to the hydraulic motor M by the cam action of the inner ring 42b. In the present embodiment, when the area H on the pump side is the suction stroke and the area I is the discharge stroke, in the area J, the second switching valve 66 is moved to the first opening position m1 with the relative rotation of the cylinder block 25. Thus, the motor port W and the second oil chamber 52 communicate with each other, and the first oil chamber 51 is disconnected. In the region J, the operating oil is sucked into the cylinder hole 39 via the second oil chamber 52, the motor port W, and the oil passage 65 by the plunger 36 performing the expansion operation.

In the region K, the second switching valve 66 is moved to the second opening position m2 with the relative rotation of the cylinder block 25, and the motor port W communicates with the first oil chamber 51. The second oil chamber 52 is not communicated. In the region K, the plunger 3 performing the contraction operation
6, the hydraulic oil is discharged from the cylinder hole 39 to the first oil chamber 51 via the oil passage 65 and the motor port W.

When the region H on the pump side is in the discharge stroke and the region J is in the suction stroke, the cylinder hole 39 in the region J
From the second oil chamber 52 through the oil passage 65 and the motor port W.
Hydraulic oil is discharged. At this time, in the region K, hydraulic oil is sucked into the cylinder hole 39 via the first oil chamber 51, the motor port W, and the oil passage 65.

The cylinder hole 29, the cylinder hole 39, the first oil chamber 51, the second oil chamber 52, the first valve hole 53, the second valve hole 54,
The oil passage 55, the oil passage 65, the pump port U and the motor port W constitute a hydraulic circuit, that is, a hydraulic closed circuit.

A shaft hole 70 is formed in the input shaft 15 along the axis O in order to charge the hydraulic circuit with hydraulic oil. The shaft hole 70 has an introduction oil passage 71 in the holder 14 in the radial direction. The introduction oil passage 71 is formed in the circumferential groove 72 formed on the inner peripheral surface of the holder 14 and the holder 14 in the radial direction. The oil passage 73 communicates with the oil passage 73. Lid 1
3 is provided with an oil passage 74 communicating with the oil passage 73.
4 is filled with hydraulic oil from a charge pump (not shown).

In the input shaft 15, a pair of charge valves 75 (check valves) for opening and closing a valve seat that can communicate with the shaft hole 70 is disposed at a portion facing the first oil chamber 51 and the second oil chamber 52. Have been. The charge valve 75 opens until the hydraulic circuit is filled with hydraulic oil, and supplies the hydraulic oil in the shaft hole 70 to the hydraulic circuit. In addition, the charge valve 75 has a hydraulic oil
To prevent backflow to

An oil passage 77 is formed in the input shaft 15 at a portion facing the coil springs 57 and 67 in the radial direction. A circumferential groove 78 communicating with the pressure applying chambers 53a and 54a is formed on the inner peripheral surface of the cylinder block 25, and the circumferential groove 78 communicates with the oil passage 77. The pressure applying chambers 53a, 54a
Is filled with hydraulic oil from a charge pump (not shown) via the shaft hole 70, the oil passage 77, and the circumferential groove 78.

Next, the operation of the hydraulic oil and the coil springs 57, 67 in the pressure applying chambers 53a, 54a of the hydraulic device T configured as in this embodiment will be described. First, the operation of the hydraulic oil in the pressure applying chamber 53a and the action of the coil spring 57 will be described.

The first switching valve is operated in cooperation with the hydraulic pressure of the working oil in the pressure application chamber 53a filled by the charge pump (not shown) and the urging force of the coil spring 57 disposed in the pressure application chamber 53a. 56 is constantly pressed toward the inner ring 23b.

Then, as the cylinder block 25 rotates, the first switching valve 56 moves from the second opening position n2 to the first opening position n1. That is, with the rotation of the cylinder block 25, the cam surface 58 advances toward the output side, and presses the distal end of the first switching valve 56 toward the output side. Then, the first switching valve 56 moves toward the output side, the coil spring 57 is contracted against its own urging force, and the hydraulic oil filled in the pressure applying chamber 53a is released from the pressure applying chamber 5a.
It is discharged into the circumferential groove 78 from inside 3a.

In addition, with the rotation of the cylinder block 25, the first switching valve 56 moves from the first opening position n1 to the second opening position n2. In this case, as the cylinder block 25 rotates, the cam surface 58 retreats toward the input side. At this time, the elastic force at the time of restoration of the contracted coil spring 57 and the hydraulic pressure of the working oil filled in the pressure applying chamber 53a from the circumferential groove 78 cooperate with the retraction of the first switching valve 56. To move to the input side. That is, the first switching valve 56 has its distal end abutted on the cam surface 58,
Move toward the input side.

Since the coil spring 57 is disposed in the pressure applying chamber 53a of the cylinder block 25,
Hydraulic device T by centrifugal force accompanying rotation of cylinder block 25
Never get out of the way. And the pressure application chamber 53
Since the structure is such that the hydraulic oil discharged from a and the inflowing hydraulic oil flow in and out of each other via the circumferential groove 78, the consumption of the hydraulic oil can be suppressed.

The functions of the hydraulic oil and the coil spring 67 in the pressure applying chamber 54a are the same as those of the hydraulic oil and the coil spring 57 in the pressure applying chamber 53a.

That is, the operation of the hydraulic oil in the pressure applying chamber 54a and the action of the coil spring 67 are described in the description of the above operation by replacing the inner ring 23b with the inner ring 42b,
To the pressure applying chamber 54a and the first switching valve 56 to the second switching valve 6
6. The coil spring 57 is the coil spring 67, the cam surface 58 is the cam surface 68, the input side is the output side, the output side is the input side, the first opening position n1 is the first opening position m1, and the second opening position n2 is the second. By replacing with the opening position m2,
Since the same operation can be described, detailed description thereof is omitted.

Therefore, according to the hydraulic device T of the present embodiment, the following effects can be obtained. (1) In the present embodiment, the first switching valve 56 and the second switching valve 6
6 is pressed toward the inner ring 23b and the inner ring 42b by the cooperation of the hydraulic pressure of the working oil filled in the pressure applying chambers 53a and 54a and the urging force of the coil springs 57 and 67, respectively. Therefore, for example, the first switching valve 56 and the second
The coil springs 57 and 67 of the present embodiment are different from the coil springs of the hydraulic device in which the switching valve 66 is pressed only by the coil springs.
A and 54a having an urging force smaller by the hydraulic pressure of the working oil in the hydraulic fluid can be adopted without any trouble.

Therefore, even if the spring constant is reduced and the strength against the repetitive load is obtained, a small spring is sufficient. (2) In the present embodiment, the coil springs 57, 67 are arranged in the pressure applying chambers 53a, 54a of the cylinder block 25.

Therefore, in a hydraulic device in which a spring is provided at the tip of the plunger protruding from the cylinder block, there is a possibility that the spring will be blown off by the centrifugal force accompanying the rotation of the cylinder block. Nothing happens.

(3) In the present embodiment, the oil path for supplying hydraulic oil to the charge valve 75 and the oil path for supplying hydraulic oil to the pressure applying chambers 53a and 54a are shared. Therefore, for example, the oil passage for the charge valve 75 and the pressure applying chambers 53a, 54
The structure can be simplified as compared with a hydraulic device in which the oil passage for a is separately formed.

(4) In the present embodiment, the pressure applying chamber 53
Since the structure is such that the hydraulic oil flowing into and out of the a and 54a flows into and out of each other through the peripheral groove 78, consumption of the hydraulic oil can be suppressed. (Other Embodiments) Each of the above embodiments may be modified and embodied in the following other embodiments.

In the above embodiment, the pressure applying chambers 53a,
Although the coil springs 57 and 67 are provided in 54a, the coil springs 57 and 67 may be omitted. With this configuration, the pressure applying chambers 53a, 54a
The first switching valve 56 only uses the hydraulic pressure of the working oil supplied to the inside,
The second switching valve 66 can be pressed against the inner races 23b and 42b, respectively. Therefore, the coil spring 5
The number of parts of the hydraulic device T can be reduced by the amount of omitting 7,67.

In the above-described embodiment, the pressure applying chamber 53 is provided in the hydraulic device T having the rotatable cylinder block 25.
a, 54a and coil springs 57, 67. The present invention is not limited to this, and may be employed in a hydraulic device having a cylinder block that does not rotate the pressure applying chambers 53a and 54a and the coil springs 57 and 67. Also, the coil springs 57 and 67 are omitted, and the pressure applying chamber 53 is omitted.
a and 54a may be adopted in a hydraulic device having a cylinder block that does not rotate.

Next, technical ideas other than the invention described in the claims that can be understood from the above embodiment and other embodiments will be described below together with their effects. (A) The hydraulic circuit is provided with a charge valve, and a hydraulic oil supply side of the charge valve is directly connected to an oil passage communicating with a pressure applying chamber.
Or the hydraulic device according to claim 2. With this configuration, the oil passage for supplying the hydraulic oil to the charge valve and the oil passage for supplying the hydraulic oil to the pressure applying chamber can be shared, and the structure is reduced as compared with the case where the oil passages are formed independently. Can be simplified.

[0060]

According to the first and second aspects of the present invention, since the switching valve is pressed against the switching valve engagement member by the pressure of the hydraulic oil in the pressure applying chamber, the urging member is provided. There is no need, and the number of parts can be reduced.

According to the second aspect of the present invention, the urging force of the spring can be reduced by the pressure of the hydraulic oil as compared with the case where the switching valve is pressed against the switching valve engaging member only by the spring. In addition, the required performance can be secured and the size of the spring can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a hydraulic device according to an embodiment.

FIG. 2 is a cross-sectional view taken along line AA in FIG.

FIG. 3 is a cross-sectional view of a main part of the hydraulic device according to the embodiment on the hydraulic pump side.

FIG. 4 is a cross-sectional view of a main part of the hydraulic device of the embodiment on the hydraulic motor side.

FIG. 5 is a sectional view taken along line BB in FIG. 1;

FIG. 6 is a sectional view taken along line CC in FIG. 1;

FIG. 7 is an explanatory view showing a cam action of inner rings 23b and 42b.

[Explanation of symbols]

23b, 42b ... inner ring as a switching valve engagement member, 25
... Cylinder blocks, 26, 36 ... Plungers, 29,
39: cylinder hole, 51: first oil chamber, 52: second oil chamber,
53a, 54a: a pressure applying chamber, 56: a first switching valve as a switching valve, 57, 67 ... a coil spring as a spring, 66 ... a second switching valve as a switching valve, T: a hydraulic device.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Hiroshi Matsuyama 1-32 Chaya-cho, Kita-ku, Osaka, Osaka Prefecture Yanmar Diesel Co., Ltd. (72) Inventor Norihiko Sakamoto 1-32, Chaya-cho, Kita-ku, Osaka, Osaka Yanmar Diesel Co., Ltd. (72) Inventor Goro Nozaki 1-32, Chayacho, Kita-ku, Osaka, Osaka Yanmar Diesel Co., Ltd. (72) Yukio Kubota, 1-32 Chayacho, Kita-ku, Osaka, Japan Yanma -Agricultural machinery F term (reference) 3H070 AA01 BB06 CC34 DD05 DD16 DD47 DD64 DD82 3H071 AA03 BB01 CC33 DD12 DD13 3H084 AA07 AA16 AA43 AA45 AA51 BB09 BB23 BB26 BB27 CC02 CC12 CC32 CC39 CC48 CC64

Claims (2)

[Claims] A cylinder block for accommodating the plunger, a hydraulic circuit communicating with a cylinder hole for accommodating the plunger, and a first oil chamber or a second oil chamber provided with the cylinder hole in the hydraulic circuit.
In a hydraulic device having a switching valve for selectively communicating with an oil chamber and a switching valve engaging member for reciprocating the switching valve, a pressure applying chamber for pressing the switching valve against the switching valve engaging member with the hydraulic oil pressure. A hydraulic device comprising: 2. The hydraulic device according to claim 1, wherein a spring for pressing the switching valve to the switching valve engagement member is further provided in the pressure applying chamber.