JP2554571Y2 - Radial plunger pump - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radial plunger pump used as a pressure source for a power steering and a suspension device of an automobile.

[0002]

2. Description of the Related Art This type of radial plunger pump is
As shown in FIG. 4, a bottomed cylindrical plunger 20 housed in a cylinder 19 is pressed against a cam 10 by a spring 22, and the cam 10 causes the plunger 20 to reciprocate. And, this radial plunger pump has a cylinder block 1 near the bottom dead center of the plunger 20.
The suction chamber 14 communicates with the introduction hole 37 of the plunger 20 to introduce a liquid into the plunger 20, and at a position where the plunger 20 is raised by a predetermined amount, the suction chamber 14 and the introduction hole 3 are moved.
7, the liquid introduced into the plunger 20 is compressed to the top dead center position of the plunger 20 and discharged to the discharge hole 29 (for example, Japanese Patent Application Laid-Open No. 63-100279). Gazette).

[0003]

In such a conventional example, when the plunger 20 shifts from the suction stroke to the discharge stroke, a relatively large surge pressure is generated. Pulsation was sometimes a problem. One reason for this is considered to be that the rate of change in the flow of the liquid during the transition from the suction stroke to the discharge stroke is relatively large because the introduction hole 37 of the plunger 20 is a perfect circle. Therefore, this invention is based on the introduction hole 37 of the plunger 20.
The purpose of the present invention is to solve the above-mentioned problem by devising the shape of.

[0004]

That is, according to the first aspect of the present invention, a bottomed cylindrical plunger reciprocated in a cylinder by a cam is provided with the inside of the plunger and the suction chamber of the cylinder block. In the radial plunger pump having a plurality of introduction holes communicating with each other near the bottom dead center, the shape of the opening of the introduction hole is set in the axial direction of the plunger.
It is characterized in that it has a substantially elliptical shape in which the diameter length in the direction is longer than the diameter length in the circumferential direction of the plunger .

The invention according to claim 2 is characterized in that the introduction hole is formed by an oblique hole inclined in the axial direction of the plunger, so that the opening shape of the introduction hole is substantially elliptical. .

[0006]

The change rate of the opening area of the introduction hole during the transition from the suction stroke to the compression / discharge stroke is reduced, and the change rate of the amount of liquid introduced into the plunger is reduced.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view of a radial plunger pump showing one embodiment of the present invention, in which 1 is a housing (cylinder block). The housing 1 has a boss portion 2 at one end thereof fitted in a mounting hole 5 of a center body 4 constituting the vane pump 3 and fastened to the center body 4 with bolts 6.

Reference numeral 7 denotes a camshaft. The camshaft 7 also serves as a rotating shaft of the vane pump 3, and its tip and substantially the center 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. It is. As shown in FIG. 2, the camshaft 7 has a polygonal cam sheet 13 attached to the outer peripheral side of the cam 10 via a roller bearing 12.

An annular suction chamber 14 coaxial 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 sheet 13.
And a suction passage 18 formed of a communication hole 17 so that a liquid flows into the inside of the pipe from a pipe (not shown).

A plurality of cylinders 19 are formed radially on the outer peripheral side of the suction chamber 14, 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 portion 23 of the cam sheet 13 by a spring 22 and a plurality of introduction holes 25 formed in a cylindrical portion 24. The introduction hole 25 is formed in an elliptical shape with a major axis is positioned in the axial direction (in the vertical direction in the figure), that the plunger 2
The diameter length in the 0 axis direction is the diameter length in the circumferential direction of the plunger 20
It is formed in a longer elliptical shape. Also, this introduction hole
Reference numeral 25 communicates the suction chamber 14 with the inside of the plunger 20 near the bottom dead center of the plunger 20 so that the liquid in the suction chamber 14 is sucked into the plunger 20.

Reference numeral 26 denotes a plug screwed to the end of the cylinder 19, and the plug 26 closes the outer opening end of the cylinder 19. The retainer 28 is engaged with the lower surface 27 of the head of the plug 26, and the spring 22 is supported by the retainer 28 and its movement is guided.

Reference numeral 29 denotes a discharge path formed across the housing 1 and the center body 4. This discharge path 29 is shown in FIG.
2, one end is open to the pressure chamber 30 at the end of the cylinder 19, and the other end is formed to communicate with a hydraulic line (not shown). A check valve 31 is arranged in the middle of the discharge path 29.

Reference numerals 32 and 33 denote Os for sealing the respective engaging portions.
It is a ring. Further, 34 is an oil seal for sealing between the center body 4 and the cam shaft 7, 35 is a sealing device for sealing between the housing 1 and the cam shaft 7 positioned outside the front bearing 11.

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

When the camshaft 7 is further rotated, the plunger 20 is pushed up by a predetermined amount by the cam 10, the communication between the introduction hole 25 and the suction chamber 14 is cut off, and the suction stroke ends, and thereafter the compression / discharge stroke is started. Transition.

The introduction hole 25 of the plunger 20 is
During the compression and discharge strokes from the time when the wall is closed by the wall 9 to the time when the top dead center is reached, the same amount of liquid as the liquid introduced into the plunger 20 pushes the check valve 31 open and out of the discharge path 29. Is discharged to the hydraulic line.

In this embodiment which operates as described above, since the introduction hole 25 of the plunger 20 is formed in an elliptical shape having a long diameter in the axial direction of the plunger 20, the transition from the suction stroke to the compression / discharge stroke is made. The rate of change of the opening area of the introduction hole 25, that is, the area of the introduction hole 25 opened to the suction chamber 14 becomes smaller than that of the conventional example, and the rate of change of the amount of liquid flowing into the plunger 20 from the suction chamber 14 Becomes smaller. Therefore, the change in the flow of the liquid is reduced, the surge pressure becomes smaller than in the conventional example, and the generation of vibration and pulsation due to the surge pressure is suppressed. In addition, since the introduction holes 25 are formed in an elliptical shape whose major axis is located in the axial direction of the plunger 20, it is possible to secure a larger dimension between the introduction holes 25 than when the introduction holes 25 are perfectly circular. Become.
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, and shows an example of a method of forming the introduction hole 25 of the plunger 20. As shown in FIG. That is, the hole shape of the introduction hole 25 is made substantially elliptical by drilling a hole processing tool (for example, a drill) 36 of a perfect circular shape at a predetermined angle (θ) with respect to the wall surface of the plunger 20. is there.

In the above embodiment, the bearings for rotatably supporting the camshaft 7 are the roller bearings 8, 9 and the ball bearing (front bearing) 11, and the cam seat 13
Since the roller bearing 12 is interposed between the cam and the cam 10, the pump operation can be performed much more quietly than the conventional example, in combination with the effect of reducing the surge pressure.

The lift amount of the cam 10 and the plunger 2
The dimensions from the bottom 21 of the zero to the introduction hole 25, the opening area of the introduction hole 25, the number of the introduction holes 25, and the like can be arbitrarily set.

[0022]

As apparent from the above description, claim 1
In the invention described above, particularly, the opening shape of the introduction hole is formed in an almost elliptical shape in which the axial diameter length of the plunger is longer than the circumferential diameter length of the plunger, so that the transition from the suction stroke to the compression / discharge stroke is performed. The rate of change of the area of the opening of the inlet hole at the point of change can be reduced, and the rate of change of the amount of liquid introduced into the plunger can be reduced. Can be suppressed.

According to the second aspect of the present invention, since the introduction hole is formed by an oblique hole inclined in the axial direction of the plunger, the opening shape of the introduction hole is formed substantially in an elliptical shape. Drilling is facilitated, and the cost can be reduced.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along the line AA of FIG. 1;

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]

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

Claims (2)

(57) [Scope of request for utility model registration] A bottomed cylindrical plunger reciprocated in a cylinder by a cam is provided with a plurality of introduction holes for communicating the inside of the plunger and a suction chamber of a cylinder block near a bottom dead center of the plunger. consisting in a radial plunger pump, the opening shape of the introduction hole, the plan
The diameter length in the axial direction of the jaw is the diameter length in the circumferential direction of the plunger.
A radial plunger pump characterized in that it is formed in a substantially elliptical shape with a long length . 2. The radial hole according to claim 1, wherein the introduction hole is formed by an oblique hole inclined in the axial direction of the plunger, so that the opening shape of the introduction hole is formed to be substantially elliptical. Plunger pump.