JPH0566275U - Check valve mechanism of plunger pump - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a check valve mechanism for a plunger pump that can reliably prevent cavitation that causes abnormal noise and the like. [Structure] A valve housing 2 having an accommodation hole 5 for a check valve 4 communicating with a discharge passage 3 connected to a discharge side of a pump is provided, and a portion of the valve housing 2 surrounding a discharge port 7 of the check valve 4 is provided. A buffer portion 8 for buffering the pressure of the hydraulic fluid discharged from the discharge passage 3 is provided.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a backflow prevention mechanism for a plunger pump used as a hydraulic pressure source for, for example, a power steering device for an automobile.

[0002]

[Prior Art]

 Conventionally, in a plunger pump, as shown in FIGS. 2 to 4, a cam shaft 21 is pivotally supported in a pump housing 20, and an eccentric cam 22 is formed on the cam shaft 21. Further, in the pump housing 20, a plurality of plunger chambers 23 extending in a radial direction around the rotation center of the cam shaft 21 are provided at equal intervals so as to face the peripheral surface of the eccentric cam 22 of the cam shaft 21. The outer opening of each plunger chamber 23 is sealed with a plug stopper 24 mounted on the pump housing 20. A cylindrical plunger 25 having one end closed and the other end open is slidably housed in the plunger chamber 23, and the plunger 25 is contracted by a spring 26 between the plunger 25 and the plug 25. The closed end is constantly brought into contact with the peripheral surface of the eccentric cam 22, and a pressurizing chamber 27 is formed between the plunger 25 and the plug plug 24. The pump housing 20 is provided with a suction passage including a suction chamber 28 and the like, a discharge chamber 29, and a discharge passage 30 that communicates each pressurizing chamber 27 with the discharge chamber 29. The discharge passage 30 will be described later. Check valve mechanism is provided. That is, a valve housing 33 having a storage hole 32 for a check valve 31 communicating with a discharge passage 30 connected to the discharge side of the pump is provided in the pump housing 20, and the valve housing 33 has the valve housing 33. A discharge port 35 that is open to a cylindrical downstream passage 34 that surrounds 33 is provided. On the other hand, the plunger 25 has a suction port 36 that is opened and closed by the wall surface of the plunger chamber 23 so as to communicate with the suction chamber 28 when the plunger 25 reaches the bottom dead center and the volume of the pressurizing chamber 27 becomes maximum. Are formed in The eccentric cam 22 of the camshaft 21 causes each plunger 25 in the pump housing 20 to sequentially operate the pump in cooperation with the check valve mechanism.

[0003]

[Problems to be solved by the device]

 However, in the conventional check valve mechanism of the plunger pump, since the discharge port 35 is directly opened to the downstream passage 34, the check valve 31 is opened by the pump discharge pressure from each pressurizing chamber 27, and the pressure is increased. When the pressurized hydraulic fluid is discharged from the discharge passage 30 to the downstream passage 34 via the discharge port 35, the flow cross section suddenly expands, and the rapid pressure drop at that time causes the hydraulic fluid to flow in the downstream passage 34. There is a possibility that cavitation may occur in the area, and abnormal noise may occur.

The present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a check valve mechanism of a plunger pump that can reliably prevent the occurrence of cavitation that causes abnormal noise and the like. .

[0005]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, the present invention provides a valve housing having a check valve accommodating hole communicating with a discharge passage connected to a discharge side of a pump, and providing a check valve discharge port in the valve housing. A buffering portion that buffers the pressure of the hydraulic fluid discharged from the discharge passage is provided at the surrounding portion.

[0006]

[Action]

 With such a configuration, when the check valve is opened by the pump discharge pressure and the pressurized working fluid is discharged from the discharge passage through the discharge port, the buffer portion provided in the portion surrounding the discharge port of the valve housing. At this point, the pressure of the discharged hydraulic fluid is buffered, and there is no sudden pressure drop after ejection as in the conventional case, so cavitation does not occur.

[0007]

【Example】

 An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows a check valve mechanism according to an embodiment of the present invention. The check valve mechanism communicates with a discharge passage connected to the discharge side of the plunger pump described in the conventional art. It is provided.

A valve housing 2 provided in the pump housing 1 has a storage hole 5 for a check valve 4 that communicates with a discharge passage 3 connected to the discharge side of the pump.

In the pump housing 1, there is provided a cylindrical downstream side passage 6 which surrounds the valve housing 2 and communicates with a discharge chamber (not shown), and the upstream side of the downstream side passage 6 is connected to the valve housing 2. A buffer portion 8 for buffering the pressure of the hydraulic fluid discharged from the discharge passage 2 is provided at a portion of the check valve 4 surrounding the discharge port 7. More specifically, the buffer portion 8 is arranged in the pump housing 1 so as to surround the valve housing 2 and gradually expand the flow passage cross section to the downstream passage 6 side. The connection passage 9 having a diameter smaller than that of the downstream passage 6. The wall surface 9a of the connection passage 9 and the outer peripheral surface 2a of the valve housing 2 facing the wall surface 9a constitute a buffer portion 8 having the discharge port 7 opened at the rear end. Although the wall surface of the connection passage 9 is changed stepwise without changing the outer peripheral surface 2a of the valve housing 2 in the drawing, the wall surface 9a of the connection passage 9 or the outer peripheral surface of the valve housing 2 facing the wall surface 9a is changed. At least one of 2a may be changed, and it may be formed in a taper shape instead of the step shape.

The check valve 4 includes a valve seat portion 10 formed in the discharge passage connecting portion of the valve housing 2, a valve body 11 seated on the valve seat portion 10, and the valve body 11 on the side of the valve seat portion 10. And a spring 12 that biases the

In the above configuration, when the hydraulic fluid is discharged from the plunger pump to the discharge passage 3, the valve body 11 is pushed by the discharge pressure that overcomes the spring force of the spring 12 and is separated from the valve seat portion 10. The check valve 4 is opened, and the pressurized hydraulic fluid is discharged from the discharge passage 3 to the buffer portion 8 via the discharge port 7, and then the flow cross section gradually expands toward the downstream passage 6 to discharge the hydraulic fluid. The cavitation does not occur because the pressure in the tank is buffered and there is no sudden pressure drop after the jet.

Further, as long as the discharge pressure does not act, the valve body 11 is in contact with the valve seat portion 10 and the check valve 4 is closed by the urging force of the spring 12, so that the reverse flow of the discharge hydraulic fluid does not occur. The discharge hydraulic fluid is continuously discharged from the discharge passage 3 into the discharge chamber.

[0014]

[Effect of the device]

 As described above, the present invention provides the valve housing having the check valve accommodation hole communicating with the discharge passage connected to the discharge side of the pump, and at the portion surrounding the check valve discharge port in the valve housing, Since the buffer portion for buffering the pressure of the hydraulic fluid discharged from the discharge passage is provided, it is possible to suppress the occurrence of cavitation and prevent the generation of abnormal noise due to cavitation.

[Brief description of drawings]

FIG. 1 is a sectional view showing a check valve mechanism of a plunger pump according to an embodiment of the present invention.

FIG. 2 is a sectional view showing an entire conventional plunger pump.

FIG. 3 is an enlarged sectional view showing a check valve mechanism of the plunger pump shown in FIG.

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

[Explanation of symbols]

 2 Valve housing 3 Discharge passage 4 Check valve 5 Storage hole 6 Downstream passage 7 Discharge port 8 Buffer section

Claims (1)

[Scope of utility model registration request] 1. A valve housing having a check valve housing hole communicating with a discharge passage connected to a discharge side of a pump, the discharge passage being provided at a portion of the valve housing surrounding a discharge port of the check valve. A check valve mechanism for a plunger pump, which is provided with a buffer section for buffering the pressure of the hydraulic fluid discharged from the check valve mechanism.