JPH0524967U - Radial plunge pump - Google Patents

Abstract

(57) [Summary] [Purpose] To reduce the surge pressure generated during the transition from the intake stroke to the compression / discharge stroke, and to suppress the occurrence of vibration and pulsation due to the surge pressure. [Structure] A bottomed cylindrical plunger 20, which is reciprocally operated in a cylinder 19 by a cam 10, has an introduction hole for communicating the inside of the plunger 20 with the suction chamber 14 of the cylinder block 1 in the vicinity of the bottom dead center of the plunger 20. It is a radial plunger pump in which a plurality of 25 are formed, and the introduction hole 25 is formed in a substantially elliptical shape. Therefore, the introduction hole 2 at the time of transition from the suction stroke to the compression / discharge stroke
The rate of change of the opening area of No. 5 becomes small, and the plunger 20
The rate of change in the amount of liquid sucked into the inside becomes small, and the change in the flow of liquid is moderated.

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 and suspension devices of automobiles.

[0002]

[Prior Art]

 As shown in FIG. 4, this type of radial plunger pump presses a bottomed cylindrical plunger 20 housed in a cylinder 19 against a cam 10 with a spring 22 and causes the cam 20 to reciprocate the plunger 20. It has become. The radial plunger pump causes the suction chamber 14 of the cylinder block 1 and the introduction hole 37 of the plunger 20 to communicate with each other in the vicinity of the bottom dead center of the plunger 20 to introduce the liquid into the inner portion of the plunger 20. The suction chamber 14 and the introduction hole 37 are cut off from each other at a position elevated by a predetermined amount, and the liquid introduced into the plunger 20 up to the top dead center position of the plunger 20 is compressed and discharged to the discharge hole 29. (See, for example, Japanese Patent Laid-Open No. 63-100279).

[0003]

[Problems to be solved by the device]

 In such a conventional example, a relatively large surge pressure is generated when the plunger 20 shifts from the suction stroke to the discharge stroke, and vibration and pulsation due to the surge pressure may be a problem. .. It is considered that this is because the introduction hole 37 of the plunger 20 has a perfect circle, and therefore the rate of change of the liquid flow at the time of transition from the suction stroke to the discharge stroke is relatively large. Therefore, the present invention aims to solve the above problems by devising the shape of the introduction hole 37 of the plunger 20.

[0004]

[Means for Solving the Problems]

 That is, according to the present invention, a bottomed cylindrical plunger that is reciprocally operated in the cylinder by a cam is provided with a plurality of introduction holes that connect the inside of the plunger and the suction chamber of the cylinder block near the bottom dead center of the plunger. The radial plunger pump is characterized in that the introduction hole is formed in a substantially elliptical shape.

[0005]

[Action]

 The change rate of the opening area of the introduction hole becomes small at the time of transition from the suction stroke to the compression / discharge stroke, and the change rate of the amount of liquid introduced into the plunger becomes small.

[0006]

【Example】

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

FIG. 1 is a sectional view of a radial plunger pump showing an embodiment of the present invention, in which 1 is a housing (cylinder block). A boss portion 2 at one end of the housing 1 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 by bolts 6.

Reference numeral 7 is a cam shaft. The cam shaft 7 also serves as the rotating shaft of the vane pump 3, and its tip and substantially central portion are supported by roller bearings 8 and 9, and the vicinity of the eccentric cam 10 is supported by a front bearing (ball bearing) 11. There is. As shown in FIG. 2, the cam shaft 7 has a polygonal cam seat 13 attached to the outer peripheral side of the cam 10 via roller bearings 12.

An annular suction chamber 14 concentric with the camshaft 7 is formed in the housing 1. The suction chamber 14 is formed in such a size that a predetermined gap is formed between the suction chamber 14 and the cam seat 13, communicates with a suction passage 18 composed of an axial hole 15, an annular space 16 and a communication hole 17, and is not shown in the drawing. The liquid is made to flow into the inside from the pipe.

On the outer peripheral side of the suction chamber 14, a plurality of cylinders 19 are radially formed as shown in FIG. The cylinder 19 is opened to the suction chamber 14, and a bottomed cylindrical plunger 20 is slidably accommodated therein. The plunger 20 has a bottom portion 21 pressed against a flat surface portion 23 of the cam seat 13 by a spring 22, and a plurality of introduction holes 25 are formed in a cylindrical portion 24 thereof. The introduction hole 25 is formed in an elliptical shape whose major axis is located in the axial direction (vertical direction in the drawing) and communicates the suction chamber 14 and the interior of the plunger 20 near the bottom dead center of the plunger 20, The liquid in the suction chamber 14 is sucked into the plunger 20.

Reference numeral 26 denotes a plug screwed to the end portion of the cylinder 19, and the plug 26 closes the outer opening end of the cylinder 19. A lower surface 27 of the head of the plug 26 engages with a retainer 28. The retainer 28 supports the spring 22 and guides its movement.

Reference numeral 29 is a discharge passage formed across the housing 1 and the center body 4. As shown in FIGS. 1 and 2, the discharge passage 29 is formed so that one end thereof opens into the pressure chamber 30 at the end of the cylinder 19 and the other end communicates with a hydraulic pressure pipe passage (not shown). A check valve 31 is arranged in the middle of the discharge passage 29.

Incidentally, 32 and 33 are O-rings for sealing the respective engaging portions. Further, 34 is an oil seal for sealing between the center body 4 and the cam shaft 7, and 35 is a sealing device located outside the front bearing 11 for sealing between the housing 1 and the cam shaft 7.

According to the above-described structure of the embodiment, when the camshaft 7 is rotated by a power source (for example, an engine) (not shown) and the plunger 20 comes to a position near the bottom dead center, the introduction hole 25 enters the suction chamber 14. The liquid is sucked into the plunger 20 by opening.

When the cam shaft 7 further rotates, the plunger 20 is pushed up by the cam 10 by a predetermined amount, the communication between the introduction hole 25 and the suction chamber 14 is interrupted, the suction stroke ends, and thereafter the compression stroke and the discharge stroke. Transition.

During the compression / discharge process from the time when the introduction hole 25 of the plunger 20 is blocked by the wall surface of the cylinder 19 to the time of reaching the top dead center, the same amount of liquid as the liquid introduced into the plunger 20 is generated. The check valve 31 is pushed open to discharge from the discharge passage 29 to a hydraulic pressure conduit (not shown).

In this embodiment that operates as described above, since the introduction hole 25 of the plunger 20 is formed into an elliptical shape, the opening area of the introduction hole 25 at the time of transition from the suction stroke to the compression / discharge stroke, That is, the rate of change of the area of the introduction hole 25 opening to the suction chamber 14 becomes smaller than that of the conventional example, and the rate of change of the amount of liquid flowing from the suction chamber 14 into the plunger 20 becomes smaller. Therefore, the change in the flow of the liquid is alleviated, the surge pressure becomes smaller than that in the conventional example, and the occurrence of vibration and pulsation due to the surge pressure is suppressed. Further, since the introduction hole 25 is formed in an elliptical shape whose major axis is located in the axial direction of the plunger 20, the dimension between the introduction holes 25 is secured to be large as compared with the case where the introduction hole 25 is a perfect circle. You can do it. Therefore, the mechanical strength of the plunger 20 can be increased and the durability can be improved.

FIG. 3 shows another embodiment of the present invention, showing an example of a method of forming the introduction hole 25 of the plunger 20. That is, the opening of the introduction hole 25 is formed into a substantially elliptical shape by inclining the true circular hole processing tool (for example, a drill) 36 with respect to the wall surface of the plunger 20 at a predetermined angle (θ). It is a thing.

In the above embodiments, the bearings that rotatably support the cam shaft 7 are the hollow bearings 8 and 9 and the ball bearings (front bearings) 11, and the cam seat 13 and the cam 10 are Since the roller bearings 12 are interposed between the rollers, the pump operation can be significantly quieter than that of the conventional example in combination with the effect of reducing the surge pressure.

Further, the lift amount of the cam 10, the dimension from the bottom portion 21 of the plunger 20 to the introduction hole 25, the opening area of the introduction hole 25, the number of the introduction holes 25, etc. can be arbitrarily set.

[0021]

[Effect of the device]

 As described above, the present invention has a bottomed cylindrical plunger that is reciprocally operated in the cylinder by a cam and has an introduction hole that communicates the inside of this plunger with the suction chamber of the cylinder block near the bottom dead center of the plunger. This is a radial plunger pump that is formed in plural, and by forming the introduction hole in a substantially elliptical shape, the rate of change in the opening area of the introduction hole at the time of transition from the suction stroke to the compression / discharge stroke can be reduced, and Since the rate of change in the amount of liquid introduced into the runner is small, changes in the flow of liquid can be mitigated, surge pressure can be reduced, and vibration and pulsation can be suppressed.

[Brief description of drawings]

FIG. 1 is a sectional view of a radial plunger pump showing an embodiment of the present invention.

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

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

FIG. 4 is a sectional view of a main part of a conventional radial plunger pump.

[Explanation of symbols]

 1 ... Housing (cylinder block) 10 ... Cam 14 ... Suction chamber 19 ... Cylinder 20 ... Plunger 25 ... Introduction hole

Claims (1)

[Scope of utility model registration request] 1. A plurality of introduction holes are formed in a bottomed cylindrical plunger which is reciprocally operated in a cylinder by a cam, and which communicates the inside of the plunger and the suction chamber of the cylinder block in the vicinity of the bottom dead center of the plunger. The radial plunger pump according to claim 1, wherein the introduction hole is formed in a substantially elliptical shape.