JPH056160U - Swash plate type piston pump - Google Patents

Abstract

(57) [Abstract] [Purpose] A swash plate type piston pump with excellent volumetric efficiency is provided by preventing uneven wear of members and preventing hydraulic oil leakage between the cylinder block and the hydraulic oil passage. [Structure] A cylinder block 6 accommodating a plurality of pistons 10 is slidably supported on a rotary shaft 4 and is relatively non-rotatable. The end cover 2 has a gasket 21
The valve plate 11 is fixed via. The gasket 21 is a metal plate whose surface is coated with rubber, and the surface of the valve plate 11 facing the end cover is also coated with rubber. Pressing spring 1 interposed on the rotary shaft 4
4, the cylinder block 6 is pressed against the valve plate 11, and each bore 7 of the cylinder block 6 is
1 and a suction port 11a provided through the gasket 21,
21a or the discharge port 11b, 21b through the suction passage 13a or the discharge passage 13b provided in the end cover 2
Communicate with.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 According to the present invention, a piston capable of reciprocating a stroke corresponding to the tilt angle of a swash plate is housed in a bore of a cylinder block that rotates integrally with a rotary shaft, and a valve plate that slides in contact with a cylinder block and the same. The bore of the cylinder block is communicated with the suction passage or discharge passage of the hydraulic oil penetrating the end cover that receives the valve plate, and the suction and suction of the hydraulic oil based on the reciprocating motion of the piston is linked with the rotation of the rotating shaft. It relates to a swash plate type piston pump that discharges.

[0002]

[Prior Art]

 As disclosed in JP-A-48-98404, generally, in a swash plate type axial piston pump, a cylinder block is slidably and non-rotatably supported on a rotating shaft supported in a casing. A piston is slidably housed in each bore of the cylinder block surrounding the rotating shaft. A shoe provided corresponding to each piston is constantly pressed against the swash plate by a shoe retainer or the like, and the tip of the corresponding piston is rotatably and immovably connected to each shoe.

A valve plate is fixed on an end cover that constitutes a crank chamber together with a casing, and a rear end surface of a cylinder block is in sliding contact with the valve plate. With the rotation of the cylinder block, each bore sequentially communicates with an intake passage or a discharge passage penetrating the valve plate and the end cover, and the reciprocating motion of the piston sucks and discharges the hydraulic oil.

[0004]

[Problems to be solved by the device]

 In such a piston pump, a throttle portion is provided at the rear end inlet / outlet of each bore of the cylinder block so that the throttle portion receives a part of the discharge pressure when the hydraulic oil is discharged from the cylinder bore to the discharge port. The rear end surface of the cylinder block is pressed against the valve plate by pressure. Therefore, the pressing action is remarkable on the cylinder bore row side communicating with the discharge passage in the rear end surface of the cylinder block, but the pushing action is hardly generated on the cylinder bore row side communicating with the suction passage. For this reason, there is a partial contact with the valve plate on the discharge passage side of the rear end surface of the cylinder block.

Further, the reaction force of the discharge pressure of the hydraulic oil in the cylinder bore in the discharge stroke is transmitted to the swash plate via the piston and the shoe. In response to this discharge pressure reaction force, a vertical reaction force against the swash plate is generated. The resultant force of the vertical reaction force and the discharge pressure reaction force acts as a force to tilt the cylinder block in the direction of the bottom dead center, and causes a tilting moment in the cylinder block. This tilting moment acts on the rear end surface of the cylinder block in the direction to press the part corresponding to the bottom dead center position of the piston against the valve plate, and separates the part corresponding to the top dead center position of the piston from the valve plate. It acts in the direction to make it. Therefore, even on the piston bottom dead center side of the rear end surface of the cylinder block, one-sided contact with the valve plate occurs.

The uneven pressing contact of the rear end surface of the cylinder block with respect to the valve plate as described above causes uneven wear between the cylinder block and the valve plate, and at the portion where the pressing action is insufficient, A gap is created between the end face and the valve plate, causing hydraulic oil leakage.

An object of the present invention is to provide a swash plate type piston pump having excellent volume efficiency by preventing uneven wear of members and preventing hydraulic oil leakage between the cylinder block and the hydraulic oil passage. is there.

[0008]

[Means for Solving the Problems]

 In order to solve the above problems, the present invention forms a swash plate type piston pump with an elastic seal portion interposed between a valve plate and an end cover.

[0009]

[Action]

 The elastic seal portion is in close contact with both the valve plate and the end cover based on its elasticity, and fills the gap between them. The elastic seal portion elastically deforms between the valve plate and the end cover when the rear end surface of the cylinder block is biased against the valve plate. That is, the elastic seal portion contracts at the portion where the cylinder block is pressed by the valve plate. On the other hand, at the portion where the cylinder block is separated from the valve plate, the elastic seal portion is elastically expanded to prevent a gap from being formed between the valve plate and the end cover.

Therefore, even when the rear end surface of the cylinder block is biased against the valve plate, the valve plate is always brought into close contact with the rear end surface of the cylinder block, and a gap may be formed between the valve plate and the end cover. No leakage of hydraulic oil is reliably prevented.

[0011]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. As shown in FIG. 1, a rotary shaft 4 is supported between the casing 1 and the end cover 2 via bearings 5A, 5B, and a cylinder block 6 slides on the rotary shaft 4 via a spline 3. It is supported so that it can rotate relative to it. A plurality of bores 7 are formed around the axis of the cylinder block 6 that rotates integrally with the rotary shaft 4, and pistons 10 are slidably housed in the bores 7, respectively.

A valve plate 11 is fixed to the end cover 2 via a gasket 21. The valve plate 11 is provided with a suction port 11a and a discharge port 11b, which are in a long arc shape in conformity with the movement locus of the opening 7a of the bore 7. As shown in FIGS. 1 to 3, the gasket 21 is formed in the same shape as the valve plate 11, and the gasket 21 has a long arc-shaped suction port 21a corresponding to the suction port 11a and the discharge port 11b of the valve plate 11. Also, the discharge port 21b is transparently provided.

The end cover 2 is formed with a suction passage 13a and a discharge passage 13b which communicate with the suction ports 11a, 21a and the discharge ports 11b, 21b. Interlocking with the rotation of the rotary shaft 4, the bores 7 of the cylinder block 6 are alternately connected to the suction port 11a and the discharge port 11b, so that the working oil flows from the suction passage 13a to the suction ports 11a and 21a. 7, the hydraulic oil in the bore 7 is discharged to the discharge passage 13b through the discharge ports 11b and 21b.

As shown in FIG. 2, the gasket 21 has a metal plate 25 as a base material, and a rubber coating is applied to the entire surface thereof to form rubber layers 26a and 26b. Therefore, the gasket 21 has some rigidity due to the metal plate 25. A rubber layer 27 is also formed on the contact surface of the valve plate 11 with the gasket 21. The rubber layer 27 on the valve plate 11, the rubber layer 26a of the gasket 21 adjacent to the rubber layer 27, and the rubber layer 26b on the surface of the gasket 21 facing the end cover constitute an elastic seal portion.

As shown in FIG. 1, a swash plate 9 is swingably supported in the casing 1. A pressure spring 14 is provided around the rotary shaft 4 in the cylinder block 6, and its spring force acts on the cylinder block 6 via a spring receiver 15, and also a spring receiver 16, a pin 17 and a pivot 18 are provided. It acts on the shoe retainer 19 via. As a result, the shoe 8 provided on the shoe retainer 19 corresponding to each piston 10 is pressed against the annular race 9 a on the swash plate 9. The tip of a piston 10 is connected to each shoe 8 so as to be rotatable and non-pullable. Therefore, each piston 10 reciprocates a stroke corresponding to the inclination angle of the swash plate 9 as the rotary shaft 4 rotates, and sucks hydraulic oil into the bore 7 and discharges hydraulic oil from the bore 7.

A narrowed portion 6 a is formed at the rear end entrance / exit of each bore 7 of the cylinder block 6, and the inner diameter of the opening 7 a is smaller than the inner diameter of the bore 7. Therefore, a part of the discharge pressure when the piston 10 is in the discharge stroke is received by the throttle portion 6a, and the rear end surface 6b of the cylinder block 6 is pressed against the valve plate 11 by this pressure and the action of the pressing spring 14. ing.

An adjustment pin 22 is erected and supported on the end cover 2, and the amount of protrusion of the adjustment pin 22 into the crank chamber S can be adjusted by screw adjustment. A pressing spring 23 is interposed between the end wall of the casing 1 and the receiving portion 9b of the swash plate 9, and the spring force of the pressing spring 23 acts on the back surface of the receiving portion 9b via the spring seat 24. .. Since the pressing spring 23 biases the swash plate 9 in the direction of increasing the tilt angle, the receiving portion 9b of the swash plate 9 contacts the tip of the adjustment pin 22 to determine the tilt angle of the swash plate 9. As the rotary shaft 4 rotates, each piston 10 reciprocates in a stroke corresponding to the tilt angle of the swash plate 9.

By the way, even if a biased pressing condition of the rear end surface 6b of the cylinder block 6 against the valve plate 11 is generated based on the discharge pressure and the discharge pressure reaction force when the hydraulic oil is discharged from the cylinder block 6. The rubber layer 27 of the valve plate 11 and the rubber layer 26a of the gasket 21 adjacent thereto, and the rubber layer 26b formed on the surface of the gasket 21 facing the end cover 2 are the valve plate 11 and the metal plate 25, respectively. Between them and between the metal plate 25 and the end cover 2 are elastically deformed to prevent a gap from being formed between the respective members.

That is, in FIG. 1, the cylinder block 6 receives a downward tilting motion by the discharge pressure reaction force to the swash plate 9. There is a clearance between the spline 3 and the cylinder block 6, and the cylinder block 6 tilts until there is no clearance due to the tilting motion. Therefore, the lower end portion of the rear end surface 6b of the cylinder block 6 corresponding to the piston 10 (lower piston in FIG. 1) at the bottom dead center position strongly presses the lower end portion of the valve plate 11 and moves to the top dead center position. The upper end of the rear end surface 6b of the cylinder block 6 corresponding to a certain piston 10 (upper piston in FIG. 1) is urged in a direction away from the upper end of the valve plate 11.

In this case, the rubber layers 27, 26a, 26b located in the vicinity of the lower end of the valve plate 11 shown in the enlarged view of FIG. 2 contract. On the other hand, the rubber layers 27, 26a, 26b located near the upper end of the valve plate 11 elastically expand to prevent a gap from being formed between the upper end of the valve plate 11 and the end cover 2.

The discharge pressure reaction force acts on the end cover 2 side through the throttle portion 6a of the cylinder block 6, and the valve is provided on the rear end surface 6b of the cylinder block 6 on the discharge stroke side and the suction stroke side. Even when there is a difference in the pressing force against the plate 11, the elastic expansion of the rubber layers 27, 26a, 26b prevents the occurrence of a gap between the suction stroke side of the rear end face 6b and the valve plate 11.

Since the plurality of rubber layers 27, 26a, 26b are provided between the valve plate 11 and the end cover 2 as described above, the valve plate 11 and the end cover 2 are elastically deformed by the rubber layers 27, 26a, 26b. It is possible to maintain a close contact state between the rear end surface 6b of the cylinder block 6 and the valve plate 11 while preventing the generation of a gap between the valve block 11 and Therefore, according to the present embodiment, the hydraulic oil leakage between the bores 7 of the cylinder block 6 and the intake and discharge passages 13a and 13b is effectively prevented, and the volumetric efficiency of the piston pump is reduced. It can be surely prevented.

Due to the contracting and expanding actions of the rubber layers 27, 26a, 26b, the rear end surface 6b of the cylinder block 6 and the valve plate 11 are not separated from each other locally, and the surface pressure is applied to the entire sliding contact portion. Since they are equalized, the situation of one-sided contact is alleviated compared to the conventional case. Therefore, it is possible to estimate the required level of wear resistance, seizure resistance, etc. of the constituent materials of the cylinder block 6 and the valve plate 11 to be lower than in the past, and it is possible to reduce the manufacturing cost.

The present invention is not limited to the above embodiment, but may be implemented in the following modes: (1) On the surface of the gasket 21 facing the end cover 21 in the above embodiment. Omit the rubber layer 26b. (2) In the above embodiment, the rubber layer 27 on the surface of the valve plate 11 is omitted. (3) In the above embodiment, the gasket 21 is omitted and the rubber layer 27 on the surface of the valve plate 11 is formed thicker. (4) In the above embodiment, the entire gasket 21 is made of rubber.

[0025]

[Effect of the device]

 As described above in detail, according to the present invention, since the elastic seal portion is interposed between the valve plate and the end cover, uneven wear of the member is prevented and the operation between the cylinder block and the hydraulic fluid passage is prevented. This has the excellent effect of preventing oil leakage and providing a swash plate type piston pump with excellent volume efficiency.

[Brief description of drawings]

FIG. 1 is a side sectional view showing an embodiment embodying the present invention.

FIG. 2 is an enlarged sectional view of a main part.

3 is a cross-sectional view taken along the line AA of FIG.

[Explanation of symbols]

2 end covers, 4 rotation shafts, 6 cylinder blocks, 7 bores, 9 swash plates, 10 pistons, 11 valve plates, 11a suction port, 11b discharge port, 13a
Suction passage, 13b discharge passage, 26a, 26b, 27
Rubber layer that constitutes the elastic seal, S crankcase.

Claims (1)

[Claims for utility model registration] 1. A cylinder block that rotates integrally with a rotary shaft accommodates a piston that can reciprocate a stroke corresponding to the tilt angle of the swash plate, and the cylinder block Based on the reciprocating movement of the piston in conjunction with the rotation of the rotary shaft, the bore of the cylinder block communicates with the suction passage or discharge passage of the hydraulic oil that penetrates through the sliding valve plate and the end cover that receives the valve plate. A swash plate type piston pump that sucks and discharges hydraulic oil, in which an elastic seal portion is interposed between a valve plate and an end cover.