JPH0524969U - Radial plunge pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the surge pressure by reducing the sliding resistance between the plunger and cylinder during the transition from the intake stroke to the compression / discharge stroke. [Structure] A bottomed cylindrical plunger 18 housed in a cylinder 17 is reciprocated by a cam 10 to perform a suction stroke or a compression stroke.
A radial plunger pump that performs a pumping action by repeating a discharge stroke, and when the intake stroke shifts to the compression / discharge stroke, the center of the plunger 18 is arranged so that the cam 10 contacts the plunger 18 on the central axis of the plunger 18. The shaft is eccentric from the rotation center of the cam 10. Therefore, when shifting from the suction stroke to the compression / discharge stroke, the plunger 1
The cam 10 pushes up the central axis of 8 and the plunger 18 starts the compression / discharge stroke without tilting with respect to the central axis of the cylinder 17. Therefore, plunger 1
8 and the sliding resistance of the cylinder 17 become small.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a radial plunger pump used as a pressure supply source for power steering devices and suspension devices of automobiles.

[0002]

[Prior Art]

 Conventionally, in this type of radial plunger pump, as shown in FIG. 4, a bottomed cylindrical plunger 18 housed in a cylinder 17 is pressed against a cam 10 by a spring 20, and the cam 18 reciprocates the plunger 18. The working fluid sucked into the plunger 18 from the suction chamber 12 through the introduction hole 22 is compressed, and the compressed working fluid is discharged from the discharge passage 25 to the outside.

That is, the radial plunger pump exerts its pump function by repeating the suction stroke, compression stroke, and discharge stroke as described above (see, for example, JP-A-55-96374).

[0004]

[Problems to be solved by the device]

 However, in such a conventional example, as shown in FIG. 4, when shifting from the suction stroke to the compression / discharge stroke, that is, when the introduction hole 22 is blocked by the wall surface of the cylinder 17, the cam 10 is closed. Since the contact position P of is deviated from the central axis of the plunger 18, a moment in the clockwise direction in the drawing acts on the plunger 18.

Therefore, the plunger 18 compresses the liquid in the cylinder 17 in a tilted state, the sliding resistance (μF) at the start of compression of the plunger 18 increases, and the surge pressure increases. .

The present invention has been devised for the purpose of solving the above-mentioned problems of the conventional technology.

[0007]

[Means for Solving the Problems]

 That is, the present invention is a radial plunger pump that performs a pumping action by repeating a suction stroke, a compression stroke, and a discharge stroke by reciprocating a bottomed cylindrical plunger housed in a cylinder with a cam.・ The center axis of the plunger is eccentric from the center of rotation of the cam so that the cam contacts the plunger on the center axis of the plunger when shifting to the discharge stroke.

[0008]

[Action]

 When shifting from the intake stroke to the compression / discharge stroke, the cam pushes up on the central axis of the plunger, and the plunger starts the compression / discharge stroke without tilting with respect to the central axis of the cylinder.

[0009]

【Example】

 Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

1 and 2, reference numeral 1 denotes a housing (cylinder block). In this housing 1, a boss portion 2 at one end thereof is fitted into a mounting hole 5 of a center body 4 which constitutes a vane pump 3, and is fixed to the center body 4 with bolts 6.

Reference numeral 7 is a cam shaft. The cam shaft 7 also serves as the rotating shaft of the vane pump 3, its tip and substantially the center are supported by bearings 8 and 9, and the vicinity of the cam 10 is supported by a front bearing (ball bearing) 11. is there.

An annular suction chamber 12 concentric with the camshaft 7 is formed in the housing 1. The suction chamber 12 is dimensioned so that a predetermined gap is formed between the suction chamber 12 and the cam 10. The suction chamber 12 communicates with a suction passage 16 composed of an axial hole 13, an annular space 14 and a communication hole 15, The liquid is made to flow into the inside from the pipe.

A plurality of cylinders 17 are formed on the outer peripheral side of the suction chamber 12. The cylinder 17 is formed so as to be eccentric by a predetermined amount (e) with respect to the rotation center of the cam 10, and one end of the cylinder 17 is opened to the suction chamber 12.

A cylindrical bottomed plunger 18 is slidably accommodated in the cylinder 17. The bottom portion 19 of the plunger 18 is pressed against the cam 10 by a spring 20 and is reciprocated in the cylinder 17 by the cam 10. The plunger 18 is arranged so as to contact the cam 10 on its central axis when the introduction hole 22 formed in the cylindrical portion 21 is closed by the wall surface of the cylinder 17 (see FIG. 2). Yes (that is, the eccentricity (e) between the rotation center of the cam 10 and the center axis of the cylinder 17 is set so as to come into contact with the cam 10 on the center axis).

When the introduction hole 22 formed in the plunger 18 opens in the suction chamber 12, the inside of the plunger 18 communicates with the suction chamber 12. The size and number of the introduction holes 22 can be set arbitrarily.

Reference numeral 23 is a plug screwed to the end of the cylinder 17, and the plug 23 closes the open end of the cylinder 17 on the external side. A retainer 24 is engaged with the lower surface of the head of the plug 23, and the retainer 24 supports the spring 20 and guides its movement.

Reference numeral 25 is a discharge passage formed across the housing 1 and the center body 4. The discharge passage 25 is formed so that one end thereof opens into the pressure chamber 26 at the end of the cylinder 17 and the other end communicates with a hydraulic pressure pipe passage (not shown). A check valve 27 is arranged in the middle of the discharge passage 25.

Incidentally, 28, 29 and 30 are O-rings for sealing the respective engaging portions. Further, 31 is an oil seal for sealing between the center body 4 and the cam shaft 7, and 32 is a sealing device located outside the front bearing 11 for sealing between the housing 1 and the cam shaft 7. .

According to the structure of the above embodiment, when the camshaft 7 is rotated by a power source (for example, an engine) (not shown) and the introduction hole 22 of the plunger 18 opens in the suction chamber 12, the liquid in the suction chamber 12 Is sucked into the plunger 18.

When the cam shaft 7 is further rotated, the plunger 18 is pushed up by the cam 10 by a predetermined amount, the communication between the introduction hole 22 and the suction chamber 12 is blocked, the suction stroke is completed, and thereafter the compression stroke and the discharge stroke are started. Transition.

During the compression / discharge process from when the introduction hole 22 of the plunger 18 is blocked by the wall surface of the cylinder 17 to the time of reaching the top dead center, the same amount of liquid as the liquid introduced into the plunger 18 is generated. The check valve 27 is pushed open to discharge from the discharge passage 25 to a hydraulic pressure conduit (not shown).

In this embodiment, which operates as described above, the cam 10 pushes up on the central axis of the plunger 18 during the transition from the suction stroke to the compression / discharge stroke (see FIG. 2), and the plunger 18 moves to the cylinder 17 The compression / discharge process is started without tilting with respect to the central axis of. Therefore, the sliding resistance between the plunger 18 and the cylinder 17 at the time of transition from the suction stroke to the compression / discharge stroke becomes small, and the surge pressure becomes small.

Further, since the sliding resistance is reduced, the wear of the plunger 18 and the cylinder 17 is reduced, the deterioration of the pump performance (the decrease of the discharge amount) due to this wear can be prevented, and the durability can be improved. it can.

As shown in FIG. 3, the cam seat 35 may be attached to the outer periphery of the cam body 33 via the bearing 34 to form the cam 10, and the cam 10 may be brought into contact with the plunger 18.

[0025]

[Effect of the device]

 As is clear from the above description, the present invention is designed so that the rotation center of the cam and the center axis of the plunger may contact with each other on the center axis of the plunger during the transition from the suction stroke to the compression / discharge stroke. The eccentricity prevents the plunger from tilting during the transition from the intake stroke to the compression / exhaust stroke and reduces the sliding resistance between the plunger and cylinder, thus reducing the surge pressure. At the same time, the wear of the plunger and the cylinder is reduced, the durability of the radial plunger pump is improved, and the predetermined pump function can be exerted for a long period of time.

[Brief description of drawings]

FIG. 1 is a sectional view of a radial plunger bump according to an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG.

FIG. 3 is a sectional view showing another embodiment of the present invention.

FIG. 4 is a sectional view of a main part showing a conventional example.

[Explanation of symbols]

 10 ... Cam 17 ... Cylinder 18 ... Plunger

Claims (1)

[Scope of utility model registration request] 1. A radial plunger pump that performs a pump action by repeating a suction stroke to a compression / discharge stroke by reciprocating a bottomed cylindrical plunger housed in a cylinder with a cam, and shifting from the suction stroke to the compression / discharge stroke. The radial plunger pump is characterized in that the center axis of the plunger is eccentric from the center of rotation of the cam so that the cam comes into contact with the plunger on the center axis of the plunger.