JP2924400B2 - Axial piston machine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an axial piston machine which mainly uses oil as a working fluid and is used as a hydraulic pump in various hydraulic systems.

[0002]

2. Description of the Related Art Conventionally, as disclosed in Japanese Patent Publication No. 57-43744 and shown in FIG. 4, a cylinder block B for holding a plurality of pistons P freely forward and backward, and a piston block A cradle-type swash plate S for receiving the head via a free-swinging shoe U and restricting the reciprocating stroke of the piston P; and a main shaft D connected to one side of the cylinder block B via a spline R. The outer peripheral portion of the skirt portion F integrated with the cylinder block B is supported by the main body housing A via the needle roller bearing N while being supported by the bearing V. Thus, the piston P is reciprocated by the rotation of the cylinder block B driven by the main shaft D, and the oil sucked from the low pressure port L is discharged toward the high pressure port H. At this time, the main shaft D is not supported at both ends using a pair of bearings at both ends, but by using the outer peripheral portion of the cylinder block B as one of the bearing support portions, the overall length is reduced. Therefore, the size of the apparatus can be reduced. In FIG. 4, C is an operation plunger for controlling the inclination angle of the swash plate S.

[0003]

However, in the above, since the outer peripheral portion of the cylinder block B is bearing-supported by using the needle roller bearing N, the rotation of the roller constituting the bearing N causes There is a problem that relatively large noise and vibration are generated.

In this case, it is conceivable to use a cylindrical sliding bearing in place of the needle roller bearing N. However, even if the sliding bearing is simply replaced, the outer peripheral portion of the cylinder block B has a lower peripheral speed than the inner peripheral portion. Therefore, simply immersing the sliding bearing in the leaking oil filled in the main body housing A results in insufficient formation of an oil film on the sliding surface, and cannot effectively reduce noise and vibration. In addition, there is a problem in that the durability of the bearing is disadvantageous, and there is a problem that the life of the bearing is shortened.

According to the present invention, despite the fact that the outer peripheral portion of the cylinder block is supported by the sliding bearing, a sufficient oil film can be formed on the sliding surface, and the bearing is small in size, low in noise and vibration, and durable. The main object is to provide a high axial piston machine.

[0006]

In order to achieve the main object, first, a cylinder block 3 for holding a plurality of pistons 2 in a main body housing 1 so as to freely advance and retreat.
And a swash plate 4 disposed on the head side of the piston 2 and restricting the reciprocating stroke of the piston 2, wherein an outer peripheral portion of the cylinder block 3 is provided with a cylindrical sliding bearing 5. To the swash plate 4 on one side sandwiching the slide bearing 5
The first chamber 6 facing the outer periphery of the cylinder block 3 on the other side
The second chambers 7 facing the respective sections were provided, and the second chambers 7 were connected to a low-pressure port 9 connected to the cylinder block 3 via a communication passage 8.

Second, in order to further simplify the construction by enabling internal drain and eliminating the need for external drain piping,
In addition to the first means, an internal drain passage 10 is provided between the first chamber 6 and the low pressure port 9, and an excessive pressure increase in the first chamber 6 is provided in the internal drain passage 10 by the low pressure port 9. The relief valve 11 was provided to keep the differential pressure between the first chamber 6 and the second chamber 7 within a certain range.

[0008]

According to the first means, since the second chamber is connected to the low-pressure port through the communication passage, the internal pressure of the second chamber is lower than that of the first chamber, and the pressure of the piston is reduced. The oil remaining in the first chamber 6 due to leakage from the head or the like is forcibly moved toward the second chamber 7 by the pressure difference. Thereby, the sliding bearing 5 interposed in the section between the first chamber 6 and the second chamber 7
An oil film can be formed satisfactorily on the sliding surface of. In this way, the oil film formed on the sliding bearing 5 can reduce and receive the impact force of the cylinder block 3 and use the cylindrical sliding bearing 5 as a bearing for supporting the outer peripheral portion of the cylinder block 3 such as a roller. With the abolition of the rolling elements, low noise and low vibration can be achieved. In addition, the sliding characteristics of the sliding bearing 5 can be improved, and the durability of the bearing 5 can be improved.

When the internal pressure in the first chamber 6 is excessively increased by the second means, the relief valve 11 is operated to open the internal drain passage 10 and the oil in the first chamber 6 is supplied to the low pressure port 9 side. Escaped to Thereby, the pressure difference between the first chamber 6 and the second chamber 7 can be kept within a certain range, and furthermore, the oil provided inside the first chamber 6 outside the main body housing 1 via the external drain pipe is provided. The need for connection to the tank can be eliminated, the internal drain system can be realized, and the configuration can be simplified.

[0010]

FIG. 1 shows a hydraulic pump using oil as a working fluid, and a cylinder for holding a plurality of pistons 2 in a body housing 1 having a cover 1a on one side. A block 3 and a cradle type swash plate 4 which is disposed on the head side of the piston 2 and regulates the advance / retreat stroke of the piston 2 are provided.

The cylinder block 3 includes a main housing 1.
And is connected to a main shaft 33 supported by bearings 31 and 32 via a spline 34 and a low pressure port 9 and a discharge port via a valve plate 35 disposed on the back side on the anti-swash plate side. 90. An oil seal 36 is interposed at the end of the main shaft 33.

The swash plate 4 receives the head of the piston 2 via a shoe 21 which can swing freely. As shown in FIG. 2, the swash plate 4 is always maximally controlled by a bias mechanism 43 comprising a spring 41 and a pressing body 42. It is held in the inclined position,
Operation plunger 44 provided on the other side of bias mechanism 43
The tilt angle can be changed toward the neutral side by the operation of. The shoe 21 interposed on the head of the piston 2 is held by a retainer 22.
Numeral 2 is slidably engaged with a retainer guide 24 which is urged by a spring 23 which is locked in a central shaft hole 37 of the cylinder block 3. The head of the piston 2 and the shoe 21 are provided with an oil supply passage 25 for supplying oil to the receiving surface of the swash plate 4.

In this manner, the rotation of the cylinder block 3 accompanying the rotation of the main shaft 33 causes the piston 2 to reciprocate by a span corresponding to the inclination angle of the swash plate 4, and directs oil sucked from the low-pressure port 9 toward the high-pressure port 90. It discharges.

With the above structure, a skirt portion 38 is integrally formed on the outer peripheral portion of the cylinder block 3 located on the swash plate side, and the cylindrical sliding bearing 5 is interposed on the outer peripheral portion of the skirt portion 38. The outer peripheral portion of the cylinder block 3 is supported inside the main body housing 1 by the sliding bearing 5. A second chamber 7 is provided on an outer peripheral portion of the cylinder block 3 located on the side opposite to the swash plate with the sliding bearing 5 interposed between the first chamber 6 facing the swash plate 4 and a second chamber 7. To the communication passage 8
To the low pressure port 9 via the

Further, an internal drain passage 10 is provided between the first chamber 6 and an upstream portion of the low-pressure port 9 at a portion where the communication passage 8 is connected.
And a valve body 11a, a valve seat 11b facing the valve body 11b, and a biasing spring 11c are provided at an opening step on the side of the first chamber 6 in the internal drain passage 10 so that an excessive pressure increase in the first chamber 6 is prevented. A relief valve 11 is provided to escape to the low pressure port 9 side and maintain a differential pressure between the first chamber 6 and the second chamber 7 within a certain range.

With the above configuration, the second chamber 7 is connected to the low pressure port 9 via the communication passage 8, so that the internal pressure of the second chamber 7 is kept lower than that of the first chamber 6. In the first chamber 6, oil leaking from a fitting portion between the head of the piston 2 and the shoe 21 or oil leaking from a contact portion between the shoe 21 and the swash plate 4,
Alternatively, it is filled with oil or the like leaking from the contact portion between the valve plate 35 and the cylinder block 3 to the central shaft hole 37 side. Thus, the oil remaining in the first chamber 6 is forcibly moved from the first chamber 6 to the second chamber 7 due to the pressure difference between the first chamber 6 and the second chamber 7. . As a result, an oil film can be favorably formed on the sliding surface of the slide bearing 5 interposed in the partition between the first chamber 6 and the second chamber 7. The impact force can be reduced and received, and the rolling element such as a roller is eliminated by using a cylindrical sliding bearing 5 as a bearing for supporting the outer peripheral portion of the cylinder block 3, thereby lowering noise and reducing noise. Vibration can be achieved, the sliding characteristics of the sliding bearing 5 can be improved, and the durability of the bearing 5 can be improved.

Further, in the above-described configuration, since the relief valve 11 is interposed between the first chamber 6 and the suction port 9, the first chamber 6
If the internal pressure of the internal
Is opened and the oil in the first chamber 6 is released to the low pressure port 9 side, so that the pressure difference between the first chamber 6 and the second chamber 7 can be kept within a certain range. Need not be connected to an oil tank provided outside the main body housing 1 via an external drain pipe, the internal drain system can be realized, and the configuration can be simplified. It is.

Of course, it is not always necessary to employ the internal drain system, and the first chamber 6 may be connected to the external oil tank 62 via the external drain pipe 61 as shown in FIG. In this case, the internal drain passage 10 and the relief valve 11 need not be provided, and the internal pressure of the first chamber 6 is slightly higher than the pressure of the external oil tank 62 due to the pipe resistance of the external drain pipe 61. In addition, the pressure can be maintained within a predetermined pressure range, and the sliding bearing 5
An oil film can be formed satisfactorily.

[0019]

As described above, according to the first aspect of the present invention, the outer peripheral portion of the cylinder block 3 extends from the first chamber 6 facing the swash plate 4 side.
The oil can be forcibly moved toward the second chamber 7 facing the sliding bearing 5, and an oil film can be formed on the sliding surface of the sliding bearing 5. Therefore, the sliding bearing 5 serves as a bearing for supporting the outer peripheral portion of the cylinder block 3. In addition to the use of rolling elements such as rollers, the noise and vibration can be reduced, and the sliding characteristics of the sliding bearing 5 can be improved to improve the durability of the bearing 5. It can do so and extend its lifespan.

According to the second aspect of the present invention, the oil tank provided inside the first chamber 6 outside the main body housing 1 via the external drain pipe by the internal drain passage 10 and the relief valve 11. It is possible to eliminate the necessity of connection to the power supply, realize the internal drain system, and simplify the configuration.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a first embodiment of an axial piston machine according to the present invention.

FIG. 2 is a plan sectional view of the first embodiment.

FIG. 3 is a side sectional view showing the second embodiment.

FIG. 4 is a sectional view of a conventional axial piston machine.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Main body housing 2 Piston 3 Cylinder block 4 Swash plate 5 Sliding bearing 6 First chamber 7 Second chamber 8 Communication passage 9 Low pressure port 10 Internal drain passage 11 Relief valve

Claims (2)

(57) [Claims] 1. A cylinder block 3 for holding a plurality of pistons 2 freely reciprocating inside a main body housing 1, and a swash plate disposed on the head side of the piston 2 for restricting the reciprocating stroke of the piston 2. And an outer peripheral portion of the cylinder block 3 is supported by the housing 1 via a cylindrical sliding bearing 5, and is disposed on one side of the sliding bearing 5 on the side of the swash plate 4. The first
One chamber 6 faces the outer periphery of the cylinder block 3 on the other side.
An axial piston machine, wherein a second chamber 7 is provided, and the second chamber 7 communicates with a low pressure port 9 connected to the cylinder block 3 via a communication passage 8. 2. An internal drain passage (10) is provided between the first chamber (6) and the low pressure port (9), and an excessive pressure rise in the first chamber (6) is released to the low pressure port (9) through the internal drain passage (10). The axial piston machine according to claim 1, further comprising a relief valve (11) for maintaining a differential pressure between the first chamber (6) and the second chamber (7) within a certain range.