JPH09236079A - Radial plunger pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress occurrence of vibration and a noise due to the unbalance of the rotation of a pump by eliminating the dispersion of the intake amount of working liquid per cylinder hole, and also always stabilizing the rotation of the pump. SOLUTION: A plurality of cylinder holes 17 is arranged to the circumferential wall of a suction chamber 16 in which an eccentric cam 15 is stored, and a plunger 18 equipped with a port 20 on its circumferential wall is stored in each cylinder hole 17. An intake passage 29 is formed in a driving shaft 12, and the opening 32 of the intake passage 29 is arranged in a position where the plunger 18 of a cam base 25 is projected to a maximum extent. The opening 32 is directed to the plunger 18 whose suction port 20 is always opened to the maximum extent when the driving shaft 12 is rotated. The inside of an intake chamber 20 is agitated by the displacement of the opening 32 accompanied by the rotation of the driving shaft 12, and remaining of air in the suction chamber 16 is suppressed.

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 hydraulic power source for a power steering device of an automobile, and more particularly to uniformizing the intake amount of hydraulic fluid in each radially arranged cylinder chamber. Regarding radial plunger pump.

[0002]

2. Description of the Related Art As a radial plunger pump of this type, one shown in FIG. 3 has been conventionally developed.

In this radial plunger pump, a suction chamber 3 is provided in the outer region of an eccentric cam 2 which is integrally provided on the drive shaft 1, and a cylinder hole 4 is radially formed on the peripheral wall of the suction chamber 3 and A plunger 5 which is pushed by the eccentric cam 2 and moves forward and backward is slidably fitted in each cylinder hole 4. A plurality of suction holes 6 are formed on the peripheral wall of each plunger 5, and the working fluid in the suction chamber 3 is sucked into the cylinder hole 4 through the suction holes 6 when the plunger 5 is projected. There is. The working fluid is introduced into the suction chamber 3 through the suction passage 8 formed in the housing 7, and the working fluid discharged from the cylinder hole 4 is sent out to the discharge passage 10 through the check valve 9. ing.

Incidentally, this technique is disclosed in, for example, Japanese Patent Laid-Open No. 2-119.
684 and the like.

[0005]

However, in the conventional radial plunger pump described above, since the cylinder hole and the plunger are radially arranged with respect to the suction chamber, the air that has entered the suction chamber together with the working fluid is sucked into the suction chamber. When accumulated in the upper side of the cylinder, the suction amount of the hydraulic fluid differs between the cylinder hole on the upper side of the suction chamber and the cylinder hole on the lower side.
Therefore, particularly during high-speed operation or the like, the pump rotation itself becomes unbalanced due to variations in the suction amount among the cylinder holes, and vibrations and noises due to this unbalanced rotation are likely to occur.

Therefore, the present invention is intended to provide a radial plunger pump capable of constantly obtaining stable pump rotation by eliminating the variation in the suction amount of the hydraulic fluid between the cylinder holes.

[0007]

As a means for solving the above problems, the present invention provides a suction chamber in the outer region of a cam that rotates integrally with a drive shaft, and a plurality of cylinders are radially arranged on the peripheral wall of the suction chamber. A hole is formed, and a plunger having a suction hole in its peripheral wall, which moves forward and backward by being pressed by the cam, is housed in each of the cylinder holes, and a cylinder is inserted from the suction chamber through the suction hole when the plunger projects. In a radial plunger pump in which the working fluid sucked into the hole is discharged to the discharge passage side when the plunger is retracted, a suction passage for introducing the working fluid into the suction chamber is formed in the drive shaft, and the suction of the suction passage The opening end on the chamber side is formed so that the suction hole formed in the plunger opens in the suction chamber. Since the opening end of the suction passage formed in the drive shaft is formed in the range in which the suction hole formed in the plunger opens into the suction chamber, the hydraulic fluid flowing from the suction passage into the suction chamber is always in the suction hole of the plunger. Is directed to the position where is opened to the suction chamber. Further, since the flow direction of the working fluid into the suction chamber changes as the drive shaft rotates, the inside of the suction chamber is agitated by the flow of the working fluid, and it becomes difficult for air to stay at a certain location. Therefore, the hydraulic fluid is uniformly supplied to each cylinder hole.

Further, if the opening end of the suction passage on the suction chamber side is formed at the position where the suction hole formed in the plunger is opened to the maximum, the hydraulic fluid is supplied most efficiently.

Further, a spiral groove may be formed in the axial passage of the suction passage. In this case,
With the rotation of the drive shaft, the spiral groove positively sends the hydraulic fluid toward the suction chamber.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to FIGS.

In the drawings, 11 is a pump casing, and 12 is a bearing 1 in the pump casing 11.
A drive shaft 15 supported through 3, 14 is an eccentric cam having a circular cross section, which is provided at a substantially central portion of the drive shaft 12 so as to be eccentric with respect to an axis O of the drive shaft 12 by a predetermined amount. .
Incidentally, O ′ in the figure indicates the circular center of the eccentric cam 15.

A suction chamber 16 having a circular cross section is provided at a substantially central portion of the pump casing 11, and the eccentric cam 15 is rotatably accommodated in the suction chamber 16. Inhalation chamber 1
Cylinder holes 17 are radially provided in the peripheral wall of 6, and a plunger 18 is housed in each cylinder hole 17 so as to be movable back and forth. A spring 19 for urging the plunger 18 inward in the radial direction is further housed in each cylinder hole 17, and the tip end surface of the plunger 18 is constantly pressed against the outer peripheral surface of the eccentric cam 15 by the force of the spring 19. It has become. In addition, a plurality of suction holes 20 are formed in the circumferential wall of each plunger 18 at equal intervals in the circumferential direction, and the suction holes 20 open into the suction chamber 16 when the plungers 18 project to move. The hydraulic fluid therein is sucked into the cylinder hole 17 through the suction hole 20. On the other hand, a discharge passage 21 is formed in the vicinity of the bottom of each cylinder hole 17 so as to communicate therewith.
The hydraulic fluid pressurized inside is sent to the outside of the pump through the check valve 22 inserted in the discharge passage 21. In addition, 23 is a plug which constitutes the bottom wall of each cylinder hole 17, and 24 is an oil seal which seals between the pump casing 11 and the drive shaft 12.

By the way, the eccentric cam 15 is connected to the drive shaft 1.
Cam base 25 formed integrally with 2 and eccentric
And a thin seat cam 26 and a metal cam 27 attached to the cam base 25.
6 and the metal cam 27 are bearings 1 on the cam base 25.
The cam base 2 is arranged at a position closer to the axial position than 3
The displacement of the cam base 25 toward the non-attached portion 25a side is regulated by the stopper ring 28 fitted on the cam 5.

Further, in the case of this radial plunger pump, the suction passage 29 for introducing the working fluid into the suction chamber 16 is provided at the tip end side of the drive shaft 12 inserted into the pump casing 11. Specifically, the suction passage 29 is
It is composed of an axial path 30 formed along the axial direction from the end face of the drive shaft 12 to the center thereof, and a radial path 31 formed along the radial direction from the tip end side of the axial path 30. The proximal end of the axial passage 30 communicates with the oil tank T outside the pump, and the distal end of the radial passage 31 communicates with the suction chamber 16 at the unattached portion 25a of the cam base 25. The opening 32 at the tip of the radial path 31 is provided at an angular position at a minimum radius from the drive shaft center O of the cam base 25, that is, at an angular position at which the plunger 18 of the eccentric cam 15 is projected to the maximum. There is. In this pump, as shown in FIG. 1, when the plunger 18 projects to the maximum, the suction hole 20 of the plunger 18
Is set to open to the maximum. Further, a spiral groove 33 is provided on the inner peripheral surface of the axial passage 30, and in the spiral direction, the hydraulic fluid is drawn in the suction chamber 1 with respect to the rotation of the drive shaft 12.
It is pushed out to the 6 side.

Since the radial plunger pump has the above-described structure, when the drive shaft 12 rotates, the eccentric cam 15 sequentially pushes up the plungers 18 facing the suction chamber 16 to continuously move the plungers 18 forward and backward. Let As a result, each plunger 18 allows the hydraulic fluid in the suction chamber 16 to pass through the suction hole 20 and the cylinder hole 17 during the projecting operation.
The liquid is sucked into the inside of the cylinder, and the hydraulic fluid in the cylinder hole 17 is pressurized during the subsequent retreating operation, and the check valve 22 is opened to send it out of the pump.

At this time, the working fluid is continuously introduced into the suction chamber 16 through the suction passage 29 by the suction action of each plunger 18, and the end portion (opening 32) of the suction passage 29 on the suction chamber 16 side. Is the center O of the drive shaft of the cam base 25.
Since the drive shaft 12 is provided at the position with the smallest radius from the above, the suction hole 20 is always directed toward the direction of the plunger 18 (cylinder hole 17) that is opened to the maximum during the rotation of the drive shaft 12. Therefore, during the rotation of the drive shaft 12, the working fluid is evenly supplied to each cylinder hole 17, and the suction flow rate of the working fluid in each cylinder hole 17 is made uniform. Further, since the direction of the opening 32 of the suction passage 29 continuously changes with the rotation of the drive shaft 12, the flow of the working fluid from the suction passage 29 stirs the working fluid in the suction chamber 16 and It becomes difficult for air to stay at a specific position within 16. Therefore, this also further promotes the uniformization of the suction flow rate in each cylinder hole 17. As a result, the pump rotation is always stable, and the vibration and noise due to the unbalance of the pump rotation are suppressed.

Further, since the axial passage 30 of the suction passage 29 is formed in the central portion of the drive shaft 12 and the spiral groove 33 is formed in the inner peripheral portion thereof, when the drive shaft 12 is rotated, its drive is driven. The action of delivering the hydraulic fluid by the spiral groove 33 according to the rotation speed of the shaft 12 is obtained. Therefore, it is possible to always introduce a sufficient amount of hydraulic fluid into the suction chamber 16 and to increase the discharge control flow rate.

In the above embodiment, the suction passage 29 is provided.
Of the eccentric cam 15 of the cam base 25.
Is arranged at the position where the plunger 18 is projected to the maximum, but the suction hole 20 formed in the plunger 18 is
Any other position may be used as long as it is open at 6. However, as in the embodiment described above,
By setting the opening 32 at the position where the suction hole 20 of the plunger 18 is maximized, the hydraulic fluid is most efficiently supplied to the suction hole 20 of the plunger 18 from the opening 32 of the suction passage 29.

[0019]

As described above, according to the present invention, the suction passage for introducing the hydraulic fluid into the suction chamber is formed in the drive shaft, and the suction chamber side opening end of the suction passage is formed in the plunger. Since the hole is formed in the range that opens in the suction chamber, the hydraulic fluid flowing from the suction passage into the suction chamber is always directed to the position where the suction hole of the plunger is open in the suction chamber, and The flow of the liquid stirs the suction chamber to eliminate the accumulation of air, and as a result, the working liquid is uniformly supplied to each cylinder hole, and the pump rotation is stabilized. Therefore, it is possible to prevent vibration and noise due to variations in pump rotation.

Further, if the chamber-side opening end portion connected to the ball of the suction passage is formed at a position where the suction hole formed in the plunger is maximum opened, the hydraulic fluid is most efficiently supplied.

Further, when the spiral groove is formed in the axial path of the suction passage, the spiral groove positively sends the working fluid toward the suction chamber as the drive shaft rotates, so that the operation is performed. It is possible to increase the liquid discharge control flow rate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view 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 sectional view showing a conventional technique.

[Explanation of symbols]

 12 ... Drive shaft, 15 ... Eccentric cam (cam), 16 ... Suction chamber, 17 ... Cylinder hole, 18 ... Plunger, 20 ... Suction hole, 29 ... Suction passage, 30 ... Axial path, 32 ... Opening part (end part) ), 33 ... spiral groove.

Claims (3)

[Claims] 1. A suction chamber is provided in an outer region of a cam that rotates integrally with a drive shaft, and a plurality of cylinder holes are radially formed on a peripheral wall of the suction chamber. The cylinder holes are pressed by the cam. A plunger that moves forward and backward and has a suction hole in the peripheral wall is accommodated, and the working fluid sucked into the cylinder hole from the suction chamber through the suction hole when the plunger is projecting is discharged to the discharge passage side when the plunger is retracting. In the radial plunger pump configured as described above, the suction passage for introducing the working fluid into the suction chamber is formed in the drive shaft, and the opening end portion of the suction passage on the suction chamber side is formed with the suction hole formed in the plunger. A radial plunger pump, characterized in that an opening is formed in a range that opens into the suction chamber. 2. The opening end of the suction passage on the suction chamber side is
The radial plunger pump according to claim 1, wherein a suction hole formed in the plunger is formed at a position where the suction hole is maximized. 3. The radial plunger pump according to claim 1 or 2, wherein a spiral groove is formed in an axial path of the suction passage.