JPH0754623Y2 - Plunger pump - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION << Industrial Application Field >> The present invention relates to a plunger pump used as a hydraulic power source for, for example, a power steering device for a vehicle or a suspension.

<< Prior Art >> Some power steering devices for automobiles drive a plunger pump by the power of an engine and use its hydraulic pressure as a steering assisting force. As shown in FIG. 5, the plunger pump 1 used in this manner is composed of a casing 2, a shaft 3, a plunger 4, an elastic plate 5, bolts 6, a sealing plate 7, and the like.

An eccentric cam portion 16 is formed on the intermediate outer peripheral portion of the shaft 3, and the plunger 4 includes a piston 21 biased inward by a coil spring 24.
The end surface of is contacted with the cam surface 16a of the eccentric cam portion 16 via the metal 30, and the lubrication between the cam surface 16a and the metal 30 is performed by the hydraulic oil in the suction chamber 20.

When the shaft 3 is rotated, the eccentric cam portion 16 of the shaft 3 operates the pistons 21 of the six plungers 4. Then, the piston 21 of the plunger 4 sucks the working oil through a suction pipe (not shown), and pumps the working oil to the discharge chamber 12 via the discharge port 25 and the valve portion 26.

In this operation, the six plungers 4 are sequentially controlled in time series corresponding to the rotational position of the eccentric cam portion 16. Further, only the valve portion 26 corresponding to the operated plunger 4 is temporarily elastically deformed to the inside of the discharge chamber 12 by the hydraulic oil pressure, and the discharge port is discharged.
25 is opened and the other valve portion 26 is kept closed.

<Problems to be solved by the invention> However, in the above-mentioned conventional example, since the lubrication between the cam surface 16a of the eccentric cam portion 16 and the metal 30 is performed by the hydraulic oil in the suction chamber 20, Metal 30 at high load
Is deformed, and an oil film is cut off between the cam surface 16a and the metal 30, which causes abnormal wear and seizure of the metal 30.

The present invention has been made in view of such problems, and its purpose is to provide relief (maximum load).
At times, the metal and the cam surface of the eccentric cam part can be forcibly lubricated to prevent abnormal wear and seizure of the metal, and the mass of the shaft and the eccentric cam part can be reduced to reduce the unbalanced mass due to eccentricity. It is to provide a plunger pump capable of performing.

<< Means for Solving the Problems >> In order to achieve the above object, the present invention relates to a plunger pump in which a plunger is actuated by an eccentric cam provided on a shaft, and discharges the elastic plate into a bolt which is fixed to a casing. A relief valve that communicates the chamber with the suction chamber via the drain passage is provided, the drain passage of the relief valve is formed from the inside of the shaft to the eccentric cam portion, and a part of the drain passage is opened to the cam surface of the eccentric cam portion. There is.

<Operation> During relief, the hydraulic oil in the discharge chamber flows into the suction chamber via the drain passage of the relief valve, but at this time, the hydraulic oil in the drain passage is supplied to the cam surface of the eccentric cam part, Force lubrication between the metal.

<< Embodiment >> An embodiment of the present invention will be described in detail below with reference to FIGS.

FIG. 1 is a vertical cross-sectional view of a plunger pump according to an embodiment of the present invention, and FIG. 2 is a side cross-sectional view showing a main part taken along the line AA of FIG.

1 and 2, the plunger pump 1 is a radial plunger pump as an example, and is composed of a casing 2, a shaft 3, a plunger 4, an elastic plate 5, bolts 6, a sealing plate 7, and the like. .

The casing 2 is formed in a substantially cylindrical shape with the front and rear opened, and an intermediate partition wall 10 for partitioning the front and rear is integrally provided in an intermediate portion. At the center of the intermediate partition wall 10 is formed a communication hole 10a having a screw thread formed on the inner peripheral surface thereof. A cylindrical bearing support portion 10b is integrally provided on the front side of the intermediate partition wall 10, and a bearing metal 11 is attached to the bearing support portion 10b. Further, on the rear side of the intermediate partition wall 10, a discharge chamber 12 is formed by a sealing plate 7 attached with the rear opening closed.
The sealing plate 7 is prevented from coming off by a lock ring 13 fitted to the casing 1 on the rear side thereof, and is sealed by a seal ring 14 interposed between the sealing plate 7 and the casing 2.

The shaft 3 is arranged in the center of the casing 2 so as to extend in the front-rear direction. One end of the shaft 3 is rotatably supported by the casing 2 via the bearing metal 11 and the middle of the shaft 3 via the bearing 15, and the other end is in a state of being protruded to the front side of the casing 2. Further, an eccentric cam portion 16 is provided on the intermediate outer peripheral portion of the shaft 3.

A portion of the casing 2 to which the shaft 3 is attached via the bearing 15 is liquid-tightly closed by a seal ring 18, a packing body 19 and the like on the front side of the bearing 15, whereby a suction chamber 20 is provided.
It is in a state of being formed before and after the intermediate partition wall 10.

The plunger 4 has a piston 21 which is operated by the eccentric cam portion 16.
have. The piston 21 has a coil spring 24 whose one end is regulated to abut on the retainer 23 of the plug plug 22.
The other end is abutted, and the urging force of the coil spring 24 causes the piston 21 to be always abutted on the cam surface 16a of the eccentric cam portion 16 via the metal 30. The plungers 4 are provided at six positions at equal intervals along the circumferential direction of the casing 2. Further, six discharge ports 25 corresponding to each plunger 4 are provided so as to pass through the inside of the intermediate partition wall 10 and communicate with the discharge chamber 12 and the inside of the plunger 4. Note that the discharge-side openings of the respective discharge ports 25 are formed in the same plane portion where the communication holes 10a are opened, and are scattered at equidistant positions on the circumference drawn around the communication holes 10a. Is provided. further,
Each discharge port 25 is integrally closed by an elastic plate 5 having a plurality of openable and closable valve portions 26.

As shown as a single piece in FIG. 4, the elastic plate 5 is formed of a single elastic metal material, has a through hole 5a in the center thereof for allowing the threaded portion 6a to be inserted, and further extends outward. The six valve portions 26 extending radially are integrally provided from the outer periphery. Each of the valve portions 26 corresponds to each of the discharge ports 25, and each of the valve portions 26 is elastically deformed by the pressure of the hydraulic oil that is pumped into each of the discharge ports 25.
25 is ready to open and close.

The bolt 6 has a bulging head 6b at the other end of the threaded portion 6a, and is screwed into the communication hole 10a in a state where the threaded portion 6a is inserted into the through hole 5a. Then, with this screwing, the elastic plate 5
Is attached to the intermediate partition wall 10, and a state in which each valve portion 26 covers each discharge port 25 is obtained. Further, a through hole 6c is provided at the center of the bolt 6, and a relief valve 27 is arranged in this through hole 6c. The tip side of the through hole 6c is a regulation wall.
It has a small diameter due to the formation of 6d.

The relief valve 27 includes a ball valve 28, a return spring 24 ′,
It is composed of a pusher 30 and a hollow tail plug 31. Hollow tail plug 31
Has a through hole 31a at the center. The pusher 30 is slidable in the front-rear direction within the through hole 6c and has a hollow tail plug.
It is pressed against the 31 side by the urging force of the return spring 24 '. Further, the ball valve 28 is held in a state in which the hollow tail plug 31 is closed during normal operation by this pressing. The relief valve 27 is housed in the through hole 6a until the return spring 24 'hits the restriction wall 6d, then the pusher 30 and the ball valve 28 are sequentially mounted, and finally the hollow tail plug 31 is press-fitted. Built in.

The shaft 3 has an eccentric cam portion from the end surface of the shaft 3.
A drain passage 29 is formed through 16 cam surfaces 16a and side surfaces 16b, 16c. That is, the drain passage 29 has the shaft 3
A hole 29a extending from the end surface of the relief valve 27 facing the through hole 6c to the central portion of the shaft 3, and the eccentric cam portion from the hole 29a.
The drain passage 29 is constituted by a hole 29b that goes out to the cam surface 6a of 16 and a hole 29d that intersects with this hole 29b and goes out to both side surfaces 16b and 16c of the eccentric cam portion 16, and the drain passage 29 is an outlet of the relief valve 27. Side is connected to the suction chamber 20, and the cam surface 16a and metal 30
The lubricating oil is supplied between and.

In the plunger pump 1 configured as described above, when the shaft 3 is rotated, the eccentric cam portion of the shaft 3 is rotated.
At 16 the pistons 21 of the six plungers 4 are actuated. Then, the piston 21 of the plunger 4 sucks the working oil through a suction pipe (not shown), and pumps the working oil into the discharge chamber 12 via the discharge port 25 and the valve portion 26. In this operation, the six plungers 4 are sequentially controlled in time series corresponding to the rotational position of the eccentric cam portion 16. Further, only the valve portion 26 corresponding to the operated plunger 4 is elastically deformed inside the discharge chamber 12 by the hydraulic oil pressure to open the discharge port 25, and the other valve portions 26 are closed. Get burned. Further, the ball valve 28 of the relief valve 27 is temporarily moved to the front side together with the pusher 30 by the pressure when the pressure of the hydraulic oil pumped to the discharge chamber 12 is higher than the regulation, and the through hole 6c is formed. Open and part of the hydraulic oil in the discharge chamber 12 is returned to the suction chamber 20 via the drain passage 29.
At this time, part of the hydraulic oil is supplied to the cam surface 16a of the eccentric cam portion 16 through the hole 29c of the drain passage 29, forcibly lubricates the inner surface of the metal 30, and enters the suction chamber 20.

<Effects of the Invention> As described above, the present invention is a plunger pump in which a plunger is operated by an eccentric cam provided on a shaft, and a discharge chamber is provided inside a bolt that fixes this elastic plate to a casing. Since the relief valve communicating with the drain passage is provided, the drain passage of the relief valve is formed from the inside of the shaft to the eccentric cam portion, and part of the drain passage is opened to the cam surface of the eccentric cam portion. The hydraulic oil in the discharge chamber flows into the suction chamber through the drain passage of the, but at this time, the hydraulic oil in the drain passage is supplied to the cam surface of the eccentric cam part and the lubrication between this cam surface and the metal is forced. can do. For this reason, even if the metal is deformed under high load, the oil film is not broken between the cam surface and the metal, and abnormal metal wear and seizure can be prevented.

Further, since the drain passage of the relief valve is formed from the inside of the shaft to the eccentric cam portion, and a part of the drain passage is opened to the cam surface of the eccentric cam portion, the mass of the shaft and the eccentric cam portion can be reduced and the eccentricity can be reduced. The unbalanced mass due to can be reduced.

[Brief description of drawings]

1 is a vertical sectional view of a plunger pump according to an embodiment of the present invention, FIG. 2 is a sectional side view of a main part taken along the line AA in FIG. 1, and FIG. 3 is a sectional view taken along the line BB in FIG. Fig. 4 is a sectional view taken along the line, Fig. 4 is a front view showing a single elastic plate applied to the same pump, and Fig. 5 is a longitudinal sectional view of a conventional plunger pump. 1 ... Plunger pump, 2 ... Casing, 4 ... Plunger, 6 ... Bottle, 10a ... Communication port, 12 ... Discharge chamber, 16 ... Eccentric cam part, 16a ... Cam surface, 20 ... Suction Chamber, 21 …… Piston, 25 …… Discharge port, 26 …… Valve part, 27 ・ ・ ・
… Relief valve, 29 …… drain passage.

Claims (1)

[Scope of utility model registration request] 1. A plunger pump for operating a plunger by an eccentric cam provided with a shaft, wherein a relief valve communicating a discharge chamber with a suction chamber via a drain passage is provided, and a drain passage of the relief valve is provided from the inside of the shaft to an eccentric cam portion. A plunger pump, characterized in that it is formed over the entire length and a part of the drain passage is opened to the cam surface of the eccentric cam portion.