JPH08219008A - Plunger pump - Google Patents

Abstract

PURPOSE: To set the control discharge flow rate in the high rotation range to any desired value without bringing about large size construction of the whole pump and increase of the costs. CONSTITUTION: In a cylinder hole 43 formed in a cylinder block 31 a plunger 32 is accommodated in such a way as capable of advancing and retreating freely, and a pump chamber 44 is bounded by the cylinder hole 43 and plunger 32. A cam ring 34 is installed in eccentricity from the cylinder block 31 in a position outside thereof 31, and the end of a supply/discharge hole 46 in communication with each pump chamber 44 is left open at the end face of the cylinder block 31. A valve plate 49 is installed between a casing 33 and the cylinder block 31 and provided with a suction groove 47 and discharge groove 48 where the opening at the end face of the hole 46 is in slide contact. The suction groove 47 is formed in any open area in eccentricity to the protrusive rear of the protrusion region of the plunger 32, and the suction amount of the working oil is restricted by this suction groove 47.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plunger pump that performs a pumping action by advancing and retracting a plurality of plungers, and more particularly to a plunger pump suitable for use in a hydraulic system for an automobile.

[0002]

2. Description of the Related Art Conventionally, as a plunger pump, FIG.
A device as shown in FIG. 9 has been devised. The pump will be briefly described below.

In this plunger pump, an annular cam ring 2 which is a guide member and a cylinder block 3 which is eccentrically driven by the cam ring 2 and eccentrically rotates are accommodated in a casing 1, and the cylinder block is further provided. A plurality of cylinder holes 4 formed on the outer peripheral portion of
Plungers 5 are housed in the respective chambers so that they can move back and forth, and a plurality of pump chambers 6 are formed by the cylinder holes 4 and the plungers 5. The head of each of the plungers 5 is always in contact with the inner peripheral surface of the cam ring 2 due to centrifugal force,
When the cylinder block 3 rotates, it is guided by the cam ring 2 to repeat the forward / backward movement.

Further, the cylinder block 3 is formed with a plurality of supply / discharge holes 7 having one end communicating with each pump chamber 6 and the other end opening side by side on the same circumference of the end face of the block 3. The end surface of the cylinder block 3 at which the supply / discharge hole 7 opens is in sliding contact with the valve plate 8 serving as a supply / discharge switching member interposed between the casing 1 and the block 3. This valve plate 8 is used for the cylinder block 3
An arc-shaped suction groove 9 and a discharge groove 10 are formed on the end surface on the side in sliding contact with the suction groove 9, and the discharge groove 10 communicates with the suction passage 11 and the discharge passage 12 of the casing 1, respectively.
Then, in the projecting region a where the plunger 5 projects from the cylinder block 3, the working oil is supplied from the suction groove 9 to the supply / discharge hole 7.
To the pump chamber 6, and the hydraulic oil in the pump chamber 6 is supplied and drained in the retreat region b where the plunger 5 retreats.
The liquid is discharged to the discharge groove 10 through.

This technique is disclosed in, for example, Japanese Patent Laid-Open No. 5-33.
No. 757, etc.

However, in this plunger pump, the discharge flow rate is constantly increased and decreased in proportion to the pump rotation speed. Therefore, when it is applied to a hydraulic system for an automobile, the rotation speed of the engine, which is a drive source, is increased. The discharge flow rate becomes excessive due to the increase in the number. Therefore, when this type of plunger pump is applied to a hydraulic system for automobiles, a flow control valve is generally added to the hydraulic system in addition to the plunger pump, and excess hydraulic oil is pumped by the flow control valve. Must be returned to the inhalation side of. Therefore, when the plunger pump described above is applied to a hydraulic system for an automobile, the hydraulic system is inevitably increased in size and cost.

Therefore, as a plunger pump capable of coping with this, for example, one disclosed in Japanese Utility Model Laid-Open No. 5-17176 has been proposed in the past.

This plunger pump is shown in FIGS.
As shown in FIG. 3, a plurality of plungers 21 having suction holes 20 on the side surface are arranged on the outer peripheral portion of a cylinder block 22 so as to be able to move forward and backward, and the heads of the plungers 21 are arranged outside the cylinder block 22. An abutting annular cam ring 23 is disposed in a state of being eccentric with respect to the block 22, and when the cylinder block 22 is driven to rotate and each plunger 21 repeats forward and backward movements, it is introduced into the outer region of the cylinder block 22. The hydraulic oil is plunger 2
1 is introduced into the inside of the plunger 21 from the suction hole 20 during the projecting operation, and the hydraulic oil inside the plunger 21 is sent to the discharge passage 25 through the check valve 24 during the subsequent retracting operation of the plunger 21. .

In this plunger pump, when the pump rotation speed exceeds a certain value, the suction amount of the hydraulic oil in each plunger 21 is limited by the suction hole 20.
The discharge flow rate of the hydraulic oil can be controlled to be constant without providing a separate flow rate control valve.

[0010]

However, in the case of this conventional plunger pump, a plurality of suction holes 20 must be bored on the same circumference on the side surface of each plunger 21, so that the plunger 21 cannot be machined. In addition to being complicated, the suction holes 20 of all the plungers 21 must be changed when changing the discharge flow rate. Therefore, these tend to cause an increase in cost.

Further, in this plunger pump,
Since the working oil is sucked into the plunger 21 through the suction hole 20 on the side surface of the plunger 21, after the plunger 21 projects and the suction hole 20 opens to the outside of the cylinder block 3, the plunger 21 retreats again. Even though the plunger 21 moves to the retracting process until the suction hole 20 is completely closed, part of the hydraulic oil in the plunger 21 leaks from the suction hole 20 to the outer region of the cylinder block 3. Will come out. For this reason, there is a portion where the hydraulic oil is not substantially discharged during the retreat stroke of the plunger 21, which is one of the causes for increasing the size of the entire pump.

Furthermore, in this plunger pump, when it is desired to change the control discharge flow rate (the control discharge flow rate when the pump speed is in the high rotation range), the opening area of the suction hole 20 of each plunger 21 is changed. However, since the space around each plunger 21 is limited, when it is used to operate a hydraulic device that requires a large flow rate, such as an active suspension of an automobile, the cylinder block 22 or It is necessary to upsize each plunger 21, which also causes upsizing of the pump.

Therefore, the present invention is to provide a plunger pump capable of arbitrarily setting a controlled discharge flow rate in a high rotation range without increasing the size of the entire pump and increasing the cost.

[0014]

As a means for solving the above-mentioned problems, the present invention provides a cylinder block which is driven and rotated in a casing, and a plurality of cylinder holes formed around the central axis of the cylinder block. A plunger that is housed in each cylinder hole so as to move back and forth to form a pump chamber together with the cylinder hole, and a plurality of supply / discharge units that have one end communicating with each pump chamber and the other end opening on the same circumference of the cylinder block. A hole, a guide member that is disposed at a position facing the plunger in the casing, and sequentially guides the retracting and retracting operation of each of the plungers due to the rotation of the cylinder block, and is interposed between the casing and the cylinder block, A suction groove and a discharge groove are formed at a position in sliding contact with the opening at the other end of the supply / discharge hole, and the hydraulic oil is supplied in a protruding region where the plunger protrudes. A plunger pump comprising: a supply / discharge switching member that supplies the oil from the inlet groove to the supply / discharge hole and discharges the hydraulic oil from the supply / discharge hole to the discharge groove in a retracted region where the plunger retracts. Is biased toward the latter half of the protrusion area of the plunger so as to have an arbitrary opening area.

[0015]

When the opening area of the suction groove of the supply / discharge switching member is made small, the suction amount of the hydraulic oil in the high rotation range is largely limited, and the control discharge flow rate at this time becomes small.
On the contrary, when the opening area of the suction groove is increased, the restriction on the suction amount of the hydraulic oil in the high rotation range is reduced, and the control discharge flow rate at this time is increased. Further, in setting the opening area of the suction groove of the supply / discharge switching member, the suction groove is biased toward the latter half of the protrusion area of the plunger, so that even if the opening area is reduced. There will be no shortage of intake amount in the low speed range.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.

1 to 3, 31 is a substantially cylindrical cylinder block having a plurality of plungers 32 on its outer peripheral portion, 33 is a casing that rotatably accommodates the cylinder block 31, and 34 is a casing. The cam ring serving as a guide member is provided in a portion located outside the cylinder block 31 in the casing 33. Casing 3
3, the front body 35 and the rear cover 36 are hermetically coupled to each other, and the cam ring 34 has a bearing structure in which an outer ring 37 and an inner ring 38 are fitted through a plurality of balls 39. . The center O'of the cam ring 34 is arranged at a position eccentric to the rotation center O of the cylinder block 31 by a set amount.

Further, the cylinder block 31 is integrally and concentrically provided with a drive shaft 40 projecting to the outside of the casing 33 on one end side thereof, and an annular wall 41 is provided on an end face on the other end side. It is provided. Bearings 42 are provided on the base portion of the drive shaft 40 and the outer peripheral portion of the annular wall 41, and the cylinder block 41 is rotatably supported by the casing 33 by these bearings 42. Further, a plurality of cylinder holes 43 are radially formed on the outer periphery of the substantially central portion of the cylinder block 41, and the plungers 32 are housed in the respective cylinder holes 43 so as to be movable back and forth. Each cylinder hole 43 and plunger 2
The reference numeral 2 constitutes a pump chamber 44 that functions as a pump by the forward / backward movement of the plunger 22.

A spring 45 is housed in each pump chamber 44, and each plunger 32 is attached to the cylinder block 3.
Along with the centrifugal force associated with the rotation of 1, the spring 45 urges it radially outward so that its head always contacts the inner peripheral surface of the cam ring 34. For this reason, each plunger 32 is guided by the inner peripheral surface of the cam ring 34 as the cylinder block 31 rotates, and performs one reciprocating movement for one rotation of the cylinder block 31. Further, the bottom of each cylinder hole 43 (pump chamber 44) communicates with a supply / discharge hole 46 for sucking and discharging hydraulic oil. The other end of each of the supply / discharge holes 46 is opened at the end face in the annular wall 41 side by side on the same circumference.

Further, between the rear cover 36 and the end surface of the cylinder block 31, there is provided a valve plate 49 serving as a supply / discharge switching member having a suction groove 47 and a discharge groove 48 at a position in sliding contact with the opening of the supply / discharge hole 46. In the projecting region a where the plunger 32 projects from the outer periphery of the cylinder block 31, the hydraulic oil is supplied from the intake groove 47 to the supply / discharge hole 46 and further to the pump chamber 44, and conversely the plunger 32 retracts. In the retreat region b, the hydraulic oil in the pump chamber 44 is discharged from the supply / discharge hole 46 to the discharge groove 48. The suction groove 47 and the discharge groove 48 are formed in the casing 3
3 communicates with the suction passage 50 and the discharge passage 51, respectively. Further, the valve plate 49 has a cylindrical base portion 52 projecting from the back side thereof, and the base portion 52 is fitted in a holding hole 53 formed in the rear cover 36. A seal ring 54 seals between the base portion 52 of the valve plate 49 and the holding hole 53, and the pressure of the discharge passage 51 is introduced between the sealed portions. Therefore, the valve plate 49 is attached to the discharge passage 5
Upon receiving the pressure of 1, the front end surface of the cylinder block 31 is brought into contact with the end surface of the cylinder block 31.

The suction groove 47 and the discharge groove 48 are formed in an arc shape on the front end surface portion of the valve plate 49 as best shown in FIG. Of these, the discharge groove 48
Is a plunger 32 protruding from the cylinder block 31.
Is formed so as to extend over almost the entire retreat region b in which the piston 32 retreats. On the other hand, the suction groove 47 is biased toward the latter stage of protrusion of the protrusion region a where the plunger 32 protrudes from the outer periphery of the cylinder block 31. And is formed in an arbitrary opening area.

In the above structure, the cylinder block 3
When 1 rotates with drive shaft 40, cylinder block 3
Plunger 32 on 1 moves forward and backward,
2 in the protruding region a, the suction groove 4 of the valve plate 49
7, the working oil is sucked into the pump chamber 44, and then the working oil in the pump chamber 44 is discharged into the discharge groove 48 of the valve plate 49 in the retreat region b of the plunger 32.

In the case of this plunger pump, the control discharge flow rate of the hydraulic oil in the high rotation range is arbitrarily set by changing the opening area of the suction groove 47 of the valve plate 49. That is, in this pump, since the suction amount of the hydraulic oil is limited by the suction groove 47 of the valve plate 49, the control discharge flow rate of the hydraulic oil in the high rotation range is determined by the opening area of the suction groove 47. When the opening area of 47 is reduced, the restriction of the suction amount is increased, so the control discharge flow rate is decreased as shown in the characteristic diagram of p of FIG. 4, and conversely, the opening area of the suction groove 47 is increased. In this case, since the limit of the inhalation amount becomes small, q in FIG.
As shown in the characteristic diagram of FIG.

Further, even when the opening area of the suction groove 47 is changed, the suction groove 47 is always biased to the latter side of the projection region a of the plunger 32, so that the suction groove 47 is not formed. The reduction of the opening area does not cause a shortage of the suction amount of the hydraulic oil in the low rotation range. That is,
When the suction groove 47 is biased to the protrusion side of the protrusion region a of the plunger 32, the hydraulic oil cannot be introduced into the pump chamber 44 in the region on the latter side of the protrusion, but in this pump, Since the suction groove 47 is biased toward the latter half side of the protrusion in the protruding area a, the pump chamber 44 connected to the supply / discharge hole 46 when the feeding / discharging hole 46 is on the former side of the protrusion.
Becomes a negative pressure, and when the supply / discharge hole 46 moves to the projecting late side, the hydraulic oil for almost the entire stroke of the plunger 32 is sucked into the pump chamber 44. Therefore, when the pump is in the low rotation range, there is no shortage of the suction amount into each pump chamber 44. Therefore, it is possible to arbitrarily set the control discharge flow rate of the hydraulic oil in the high rotation range without changing the pump discharge capacity (the discharge amount per one rotation of the pump) in the low rotation range (of p and q in FIG. 4). See characteristic diagram.).

The embodiments of the present invention are not limited to those described above. For example, in the case of the above embodiments,
Although the so-called radial type plunger pump has a plurality of plungers 32 arranged in the radial direction of the cylinder block 31, a plurality of plungers are arranged in the axial direction of the cylinder block and these plungers serve as guide members. A so-called axial type plunger pump that moves back and forth by a swash plate may be used.

Further, in the above embodiment, the plate material (valve plate 49) which slidably contacts the end surface of the cylinder block 31 is used as the supply / discharge switching member. However, as shown in FIGS. Suction groove 61 and discharge groove 6 on the surface
You may make it use the rod-shaped material 63 which formed 2.

In this case, a fitting hole 64 is formed in the center of the end surface of the cylinder block 31, and the ends of the plurality of supply / discharge holes 46 communicating with the pump chamber 44 are connected to the inner peripheral surface of the fitting hole 64. The rod-shaped member 63 fixed to the rear cover 36 is fitted into the fitting hole 64 of the cylinder block 31 so as to be slidable in the rotational direction, and the suction groove 61 of the rod-shaped member 63 is also opened.
The discharge groove 62 is brought into sliding contact with the supply / discharge hole 46 in the fitting hole 64. In addition, reference numerals 65 and 66 in the drawing denote a suction passage and a discharge passage formed in the rod-shaped member 63 so as to communicate with the suction groove 61 and the discharge groove 62, respectively. Further, in FIGS. 5 and 6, the same parts as those in the embodiment shown in FIGS. 1 to 3 are designated by the same reference numerals.

Also in this case, the suction groove 61 of the rod-shaped member 63
Is biased toward the latter projection side of the projection region a of the plunger 32 and formed to have an arbitrary opening area, it is possible to obtain substantially the same effect as in the case of the above embodiment. Further, in the case of the plunger pump of this embodiment, it is not necessary to further extend the supply / discharge holes 46 extending radially inward from the respective pump chambers 44 in the axial direction. Compared with the embodiment, there is an advantage that the supply / discharge hole 46 can be easily processed. 5 and 6, the rod-shaped member 63, which is a supply / discharge switching member, is formed separately from the rear cover 36, but the rod-shaped member 63 may be formed integrally with the rear cover 36. .

[0029]

As described above, according to the present invention, the working oil is supplied to the supply / discharge hole of the cylinder block in the projecting region of the plunger, and the working oil is discharged from the supply / discharge hole to the discharge groove in the retracting region of the plunger. In the plunger pump provided with the switching member, the suction groove of the supply / discharge switching member is biased toward the latter half of the protrusion area of the plunger to form an arbitrary opening area. It is possible to arbitrarily set the control discharge flow rate in the high rotation range without causing a shortage of the intake amount. Further, unlike the conventional one, the suction hole is not formed in the side wall of each plunger, so that the size of the entire pump and the cost are not increased.

[Brief description of drawings]

FIG. 1 is a sectional view taken along line AA of FIG. 2 showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along line BB of FIG. 1 showing the same embodiment.

FIG. 3 is a front view showing essential parts of the embodiment.

FIG. 4 is a graph showing a discharge flow rate-pump rotation speed characteristic of the embodiment.

FIG. 5 is a sectional view showing another embodiment of the present invention.

FIG. 6 is a sectional view taken along the line CC of FIG. 5 showing the same embodiment.

FIG. 7 is a vertical sectional view showing a conventional technique.

FIG. 8 is a cross-sectional view taken along the line DD of FIG. 5 showing the same technique.

FIG. 9 is a front view of components showing the same technique.

FIG. 10 is a cross-sectional view showing another conventional technique.

FIG. 11 is a cross-sectional view taken along the line EE of FIG. 10 showing the same technique.

[Explanation of symbols]

 31 ... Cylinder block, 32 ... Plunger, 33 ... Casing, 34 ... Cam ring (guide member), 43 ... Cylinder hole, 44 ... Pump chamber, 46 ... Supply / drain hole, 47, 61 ... Suction groove, 48, 62 ... Discharge groove , 49 ... Valve plate (supply / discharge switching member), 63 ... Rod-shaped material (supply / discharge switching member).

Claims (3)

[Claims] 1. A cylinder block which is driven and rotated in a casing, a plurality of cylinder holes formed around a center axis of the cylinder block, and a cylinder chamber which is housed in each cylinder hole so as to be capable of advancing and retreating. A plunger to be formed, a plurality of supply / discharge holes having one end communicating with each pump chamber and the other end opening on the same circumference of the cylinder block, and a plurality of supply / discharge holes arranged in a position facing the plunger in the casing. A guide member that sequentially guides the retracting and retracting movements of the plungers as the block rotates, and a suction groove and a discharge member that are interposed between the casing and the cylinder block and that are in sliding contact with the opening at the other end of the supply / discharge hole. A groove is formed, the working oil is supplied from the suction groove to the supply / discharge hole in the projecting area where the plunger projects, and the working oil is created in the retracting area where the plunger retracts. In a plunger pump provided with a supply / discharge switching member for discharging hydraulic oil from a supply / discharge hole to a discharge groove, a suction groove of the supply / discharge switching member is biased toward a latter stage of projection in a projecting region of the plunger. Plunger pump characterized by being formed with an arbitrary opening area by means of 2. The feeding / discharging switching member is formed of a plate material which is slidably in contact with the end surface of the cylinder block while the other ends of the plurality of feeding / discharging holes are opened to the end surface of the cylinder block. The plunger pump described in 1. 3. A fitting hole is formed in an end surface of the cylinder block, the other ends of the plurality of supply / discharge holes are opened to an inner peripheral surface of the fitting hole, and the supply / discharge switching member is fitted in the fitting hole. The plunger pump according to claim 1, wherein the plunger pump is formed of a rod-shaped member that is slidably fitted into the dowel hole.