JPH0653776U - Radial plunger pump - Google Patents

Abstract

(57) [Summary] [Objective] The opening area of the suction hole is set large while ensuring the optimum formation position of the suction hole, and the pump discharge flow rate is greatly increased. A suction hole that connects the inside of the plunger 28 and the suction chamber 22 to each other in the vicinity of the bottom dead center is formed in a peripheral wall 28b of a plunger 28 that is retractably stored in a cylinder 27 radially formed in the housing 11. is doing. The suction holes 30, 30 are formed in rectangular elongated holes extending along the circumferential direction of the peripheral wall 28b.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

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

[0002]

[Prior art]

 An example of this type of radial plunger pump is disclosed in Japanese Patent Publication No. 1-33670. To explain the outline with reference to FIG. 6, in this radial plunger pump, a plurality of plungers 3 having a cylindrical shape with a bottom are housed in a cylinder 2 formed in a housing 1 so as to be capable of advancing and retracting in a radial direction. When each of the plungers 3 is pushed by the eccentric cam 4 rotating inside the housing 1 and repeatedly moves forward and backward, the working oil in the suction chamber 5 is formed into a circular suction hole 6 formed in the peripheral wall of the plunger 3. Through the discharge passage 7 to the discharge passage 7. That is, the suction chamber 5 and the suction hole 6 communicate with each other near the bottom dead center of the plunger 3 to introduce hydraulic oil into the plunger 3, and the suction chamber 5 and the suction hole 6 are connected to each other at a position where the plunger 3 is lifted by a predetermined amount or more. The hydraulic oil introduced into the plunger 3 is pressurized to the top dead center position of the plunger 3 and then discharged to the discharge passage 7.

[0003]

[Problems to be solved by the device]

 By the way, the substantial discharge flow rate of the hydraulic oil discharged to the discharge passage 7 is determined by the size of the opening area of each suction hole 6 communicating with the suction chamber 5 appropriately.

However, in the conventional plunger pump described above, since each suction hole 6 is formed in a circular shape, it is difficult to increase the actual discharge flow rate when the same specific discharge flow rate is achieved. Become. That is, since each suction hole 6 has a circular shape, if the diameter dimension is made larger than a predetermined value in order to substantially increase the discharge flow rate, the suction hole 6 and the suction chamber 5 communicate with each other as the plunger 3 moves back and forth. It becomes difficult to set the optimum relative position between the position and the shut-off position, that is, a position that does not reduce pump efficiency. Therefore, the expansion of the opening area of each suction hole 6 is naturally limited, and as a result, it becomes difficult to increase the actual discharge flow rate.

[0005]

[Means for Solving the Problems]

 The present invention has been devised in view of the above-mentioned conventional problems, in which the inner wall of the plunger and the suction chamber of the housing are provided on the peripheral wall of a bottomed cylindrical plunger which is reciprocally operated in the cylinder by a cam. In a radial plunger pump having a plurality of suction holes communicating with each other in the vicinity of the bottom dead center of the plunger, the suction holes are formed as rectangular oblong holes extending along the circumferential direction of the plunger. I am trying.

[0006]

[Action]

 According to the present invention having the above-described configuration, the suction hole is an elongated hole extending in the circumferential direction of the plunger, not in the vertical direction, so that the communication position between the suction hole and the suction chamber and the blocking position are optimal when the plunger moves forward and backward. It is possible to increase the opening area as much as possible while ensuring various position settings.

[0007]

【Example】

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

FIG. 4 shows an embodiment of a radial plunger pump according to the present invention. Reference numeral 11 denotes a housing, and this housing 11 has a boss portion 12 at one end thereof which constitutes a vane pump (not shown). It is fitted into a mounting hole 14 of 13 and is fixed to the center body 13 with bolts 15.

Reference numeral 16 in the drawing denotes a cam shaft. The cam shaft 16 also serves as the rotation shaft of the vane pump, and the tip and the substantially central portion thereof are supported by the roller bearing 17, and at the outer periphery thereof. The vicinity of the fixed eccentric cam 18 is supported by a front bearing 19. A metal cam 21 is attached to the outer peripheral side of the eccentric cam 18 via a seat cam 20.

An annular suction chamber 22 is formed inside the housing 11 at the side of the eccentric cam 18. The suction chamber 22 communicates with a pipe (not shown) through a suction passage 26 including an axial hole 23, an annular space 24, and a communication hole 25.

A plurality of cylinders 27 are radially formed on the inner peripheral side of the suction chamber 22. One end of each of the cylinders 27 is open to the suction chamber 22 and the inside thereof is A bottomed cylindrical plunger 28 is retractably housed. The bottom portion 28a of the plunger 28 is elastically contacted with the outer peripheral surface of the metal cam 21 by the spring force of the coil spring 29, and a pair of suction holes 30, 30 are formed near the lower portion of the peripheral wall 28b.

As shown in FIGS. 1 to 3, the suction holes 30 and 30 are formed in rectangular elongated holes extending along the circumferential direction of the peripheral wall 28b, respectively, and are arranged at symmetrical positions of 180 °. While being arranged, the length dimension L1 is set to be slightly smaller than the diameter dimension L2 of the plunger 28. Further, the suction holes 30, 30 are in a state where the bottom portion 28a is in contact with the peripheral wall 28b on the base circle of the eccentric cam 18 as shown in FIG. 4, that is, the lower half (at the bottom dead center position). A cross-hatched portion) is formed at a position that opens into the suction chamber 22, and at this time, the hydraulic oil in the suction chamber 22 is sucked into the plunger 28.

Reference numeral 31 in FIG. 4 denotes a discharge passage formed across the housing 11 and the center body 13. As shown in FIG. 4, one end of the discharge passage 31 is an end of the cylinder 27. While opening to the pressure chamber 32 provided in the portion, the other end communicates with a hydraulic pressure conduit not shown. Further, a check valve 33 is provided in the middle of the discharge passage 31.

In the figure, 34 is a plug that closes the upper end opening of the cylinder 27, 35 is a spring retainer fixed to the inner bottom surface of the plug 34, 36 and 37 are O-rings that seal each engaging portion, and 38 is An oil seal that seals between the center body 13 and the cam shaft 16, and 39 is a seal device that seals between the housing 11 and the cam shaft.

The operation of this embodiment will be described below. That is, when the cam shaft 16 is rotated by a crank shaft (not shown) and the plunger 28 reaches the bottom dead center position, the suction holes 30 and 30 open into the suction chamber 22 and oil is sucked into the plunger 28. It When the cam shaft 16 further rotates, the plunger 28 is pushed up by the eccentric cam 18 by a predetermined amount, the communication between the suction holes 30 and 30 and the suction chamber 22 is cut off, the suction stroke ends, and the compression stroke and the discharge stroke thereafter. And transition.

Here, since each suction hole 30, 30 is formed as a long hole along the circumferential direction of the peripheral wall 28, as shown in FIG. 1, the optimum communication position and blocking position with respect to the suction chamber 22 are set. The opening area for the suction chamber 22 can be set sufficiently large while ensuring the above. Therefore, in the case of having the same specific discharge amount, the substantial discharge flow rate can be greatly increased (hatched portion) as compared with the conventional (solid line) as shown by the broken line in FIG.

Since the suction holes 30 and 30 can be drilled by milling or the like, the machining work is relatively easy as in the case of conventional drilling.

Further, it is needless to say that the opening areas of the suction holes 30, 30, the positions in the circumferential direction, and the number of suction holes can be arbitrarily changed depending on the application device.

[0019]

[Effect of device]

 As is clear from the above description, the radial plunger pump according to the present invention, in particular, has the suction hole formed as a rectangular elongated hole extending along the circumferential direction of the plunger, so that it can be compared with the conventional circular hole. As a result, the opening area can be set as large as possible while ensuring the optimum communication position and blocking position with respect to the suction chamber. As a result, the substantial discharge flow rate of the pump can be greatly increased.

[Brief description of drawings]

FIG. 1 is a front view of a plunger used in an embodiment of the present invention.

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

FIG. 3 is a view on arrow B of FIG.

FIG. 4 is a vertical sectional view of a plunger pump according to an embodiment of the present invention.

FIG. 5 is a characteristic diagram showing a substantial discharge flow rate of this embodiment in comparison with a conventional one.

FIG. 6 is a vertical sectional view showing a conventional plunger pump.

[Explanation of symbols]

 11 ... Housing 16 ... Cam shaft 18 ... Eccentric cam 22 ... Suction chamber 28 ... Plunger 28b ... Peripheral wall 30 ... Suction hole

Claims (1)

[Scope of utility model registration request] 1. A plurality of suction holes are formed in a peripheral wall of a bottomed cylindrical plunger that is reciprocally operated in a cylinder by a cam so that the inside of the plunger and the suction chamber of the housing communicate with each other near the bottom dead center of the plunger. In the radial plunger pump described above, the suction hole is formed as a rectangular elongated hole extending along the circumferential direction of the plunger.