JPS60216078A - Variable displacement pump - Google Patents

Abstract

PURPOSE:To reduce a degree of sliding resistance between a plunger and a cam ring as well as to make a pump smoothly rotatable at high speed, besides compact in size, by setting the cam ring down to a guide ring consisting of both inner and outer rings and rollers. CONSTITUTION:An inner ring 4a coming into contact with a plunger 3 is installed. Then, an outer ring 4b is installed in an outer side of the inner ring 4a via a roller 4c. And, a first roller 51 and a second roller 61 are installed in each of first and second control pistons 50 and 60 comtacting with the outer ring 4b. With both these rollers 51 and 61, the outer ring 4b and these control pistons 50 and 60 are all constituted so as to come into rolling contact with one another.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a variable displacement radial plunger pump having a variable displacement, and is effective for use as a hydraulic power source for, for example, a power steering device.

[Prior art]

The conventional type basically consisted of a plurality of plungers provided radially around the rotor, and a cam ring that was provided eccentrically from the center of the rotational axis of the rotor and had an inner surface that slid on the tip of the plunger. . However, in these conventional plungers, a roller or a slipper shoe is provided at the tip of the plunger, that is, at the portion that slides on the cam ring, in order to reduce sliding resistance. This roller or pershoe is provided as a protrusion at the tip of the plunger, so when the plunger slides on the cam ring, there is a large resistance from the fluid inside the pump (the fluid between the cam ring and the rotor). There is a problem of receiving. This problem becomes particularly noticeable when the pump is operated at high speed, so the rotational speed of the pump cannot be increased sufficiently.

Furthermore, in order to vary the discharge flow rate from the pump, vane type pumps have been proposed that vary the amount of eccentricity between the center of the rotor's rotation axis and the center of the cam ring, but these conventional pumps There is a problem in that the mechanism for changing the amount of eccentricity of the cam ring is large and complicated. Furthermore, when moving the cam ring, the responsiveness is poor due to the sliding resistance of the side clearance portion, and there is a problem in that the discharge volume cannot be precisely controlled.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is to provide a variable displacement pump that is small in size, capable of smooth high-speed operation, and has good responsiveness.2! Therefore, the present invention is to make the cam ring a guide ring composed of an inner ring, an outer ring, and rolling elements.

〔Example〕

Next, a first embodiment of the present invention will be described based on FIGS. 1 to 4.

This is an embodiment of a variable displacement radial plunger pump, and FIG. 1 is a partial cross-sectional view of the radial plunger pump, FIG. 2 is a cross-sectional view taken along line nm in FIG. 1, and FIG.
The figure is a sectional view taken along line mm in FIG. 2, and FIG. 4 is a sectional view taken along line IV-IV in FIG. 3.

2 is a housing that forms the outer shape of the pump, and 2 is a rotor that is built into the housing 1 and rotates around O in response to external power. The rotor 2 has seven cylinder holes 21 arranged radially.
A plunger 3 is slidably inserted into each of the plungers 3 in an oil-tight manner and urged outward from the center 0 by a spring 22. The tip of the plunger ±3 has an R shape, that is, a substantially hemispherical □ shape. Further, inside the rotor 2, a pump operating chamber 23 is formed by the cylinder hole z1 and the plunger 3.

A protrusion 2a is formed at the left end of the rotor 2 in FIG. 200 is a drive shut, which is rotated by a power source such as an engine or a motor (not shown). Since the shaft 200 and the projection 2a of the rotor 2 are fastened together, the rotor 2 rotates together with the rotation of the drive shaft 200. 5 is the side housing and housing l
is fixed with bolt 6. 7 is a journal bearing, and a sliding ring 7b is press-fitted inside a reinforcing ring 7a. Since the bearing 7 is press-fitted into the housing 5, the inner peripheral surface of the sliding ring 7b is flush with the drive shaft 20.
Make a sliding contact of 0. Reference numeral 9 denotes an oil seal for preventing the working fluid in the internal space of the housing from leaking to the outside.

Reference numeral 10 denotes a bushing, which is driven into the inner circumference of the rotor 2 and rotates together with the rotor 2.

The bushing 10 is fitted to the bottle 13 in an oil-tight manner and slidably rotatable, and the material of the bushing 10 is a sliding material such as phosphor bronze. Bush 10 has
The same number of communication holes 20 as cylinder holes 21 are bored. Since the communication hole 20 has a smaller diameter than the cylinder hole 21, the bush lO receives one end of the spring 22 disposed inside the cylinder hole 21.

As can be seen in FIG. 2, a discharge groove 14 is provided at an angle corresponding to the discharge stroke of the bottle 13, and a suction groove 15 is provided at an angle corresponding to the suction stroke. Plunger 3
In the discharge stroke, which is approximately in the upper half of the figure, pump chamber 2
3 communicates with the communication hole 20 of the bush 10, the discharge groove 14 of the bottle 13, the discharge hole 16, and the discharge port 11. Also, in the suction stroke when the plunger '3 is approximately in the lower half of the diagram,
The pump chamber 23 is connected to the communication hole 20 of the bush 10 and the bottle 1
It has a structure that communicates with the suction groove 15, suction hole 17, and suction port 12 of No. 3. Furthermore, an annular groove 19 is provided on the outer periphery of the bottle 13, and this annular groove 19 communicates with the discharge hole 16 through a communication hole 18. Note that the bottle 13 is fixed to the housing 1 with bolts 6'.

On the other hand, the outer circumference of the rotor 2 includes an inner ring 4a and an outer ring 4b.
,, a guide ring 4 consisting of steel balls 4c is provided, and the outer tip of the plunger 3 contacts the inner periphery of the inner ring 4a and rotates at approximately the same speed as the rotor 2.
b is in contact with the housing 1. Here, 0' is the center of the guide ring 4, which is eccentrically provided by an eccentric amount e with respect to the center 0 of the rotor 2.

Further, on the outer periphery of the guide ring 4 on the right side in FIG.
A first control piston 50 is slidably and oil-tightly inserted, which is provided with a first shaft 52 that supports the first and tenth rollers 51. A first spring 54 supported by a camp 53 screwed into the housing 1 is provided on the back surface of the first control piston 50, and the biasing force of the first spring 54 causes the first control piston 5 to
0 urges the guide ring 4 to the left in the figure. Furthermore, the first control piston 50, the housing 1 and the cap 5
As shown in FIG. 3, the first space 55 formed by the housing 1 communicates with the annular groove 19 through a first communication hole 56 provided in the housing 1, and the discharge pressure of the hydraulic fluid is guided therethrough.

On the other hand, on the left side in FIG. 2, that is, at a position symmetrical to the first control piston 50, there is a 20th lug 61 that makes rolling contact with the outer ring 4b, and a 2nd shaft 62 that supports the 20th lug 61. Two control pistons 60 are slidably and oil-tightly inserted into the housing 1 . A second spring 64 supported by a cap 63 screwed onto the housing 1 is provided on the back surface of the second control piston 60, and the biasing force of the second spring 64 causes the 21i control piston 60 to move. The guide ring 4 is urged rightward in FIG. Furthermore, the second control piston 60
, the second formed by the housing 1 and the camp 63
The space 65 communicates with the inside of the pump 70 via a second communication hole 66 provided in the housing 1, as shown in FIG. Note that the inside of the pump 70 is connected to the suction port 1 through the suction hole 17.
It communicates with 2.

Further, 30 indicates an O-ring for sealing.

As shown in FIGS. 3 and 4, roller holding parts (59,
The side end surface of 69 is a flat surface to prevent rotation (skew), and this flat surface is arranged to be slidable on the flat surface of the housing 1.

Next, the operation will be explained based on the above configuration.

When the rotor 2 rotates clockwise in Fig. 2, the rotation center O of the rotor 2 and the center point 01 of the guide ring 4 are eccentric, so the plunger 3 performs reciprocating motion to suck in and discharge hydraulic oil. becomes. In the suction stroke when the plunger 3 is at the lower half of the 0 point, the working fluid is supplied from the suction port 12 to the pump chamber 20 through the suction hole 17, the suction groove 15, and the communication hole 20.
inhale. Next, in the discharge stroke in which the rotor 2 rotates and the piston reaches the upper half of the zero point, the fluid in the pump chamber 23 is passed through the communication hole 20, the discharge groove 14, and the discharge hole 16 to the discharge port 1.
Discharge to 1. Here, the guide ring 4 can be moved in the left-right direction in FIG.

For example, if the guide ring 4 is moved to the right in the figure, the distance between the centers 0 and 0' points, that is, the eccentricity e, becomes smaller, and the movement stroke of the plunger 3 becomes smaller.
The change in capacity of the pump chamber 23 is reduced, and the amount of fluid discharged from the discharge port 11 can be reduced.

In this embodiment, in order to reduce the load as much as possible when moving the guide ring 4 from side to side, the 10th ring 51,
The 20th ring 61 and the outer ring 4b of the guide ring 4 are in rolling contact. Also, the inner ring 4a and the outer ring 4
b is also configured to make rolling contact via the steel ball 4C.

Furthermore, since the guide ring 4 is pushed upward in FIG. 2 by the reaction force of the plunger 3 during the discharge stroke, the outer ring 4b does not simply move from side to side in FIG. When moving to the left, the outer ring 4b moves while rolling in a clockwise direction, and when moving to the right, it rolls in an inverted clockwise direction.

Capacity control in the present invention will be explained. When the discharge pressure from this pump is low, the guide ring 4 is placed in a position determined by the urging force of the first spring 54 and the second spring 64.
is located. At this time, the amount of eccentricity between the rotor 2 and the guide ring 4 is not the maximum. When the discharge pressure from the pump increases, the guide ring 4 moves to the left in the figure due to the biasing force of the discharge pressure guided to the first space 55. , and finally reaches the position shown in Figure 2. In other words, the amount of eccentricity e between the rotor 2 and the guide ring 4 gradually increases, and the discharge flow rate from the pump increases accordingly.

Next, the effects of the present invention will be explained in comparison with the conventional one.

For vane type pumps, Utility Model Application No. 57-180184
As shown in , a cylindrical member is provided on the inner peripheral surface of the housing and is rotatably supported via a plurality of rollers. However, in a vane type pump, this cylindrical member is one member that partitions the pump working chamber, so there is a space between the end face of the cylindrical member and the side housing to prevent the working fluid in the pump working chamber from flowing out. Tight clearances are required to prevent this. In other words, due to this clearance problem, the cylindrical member cannot rotate smoothly. Furthermore, since the housing and the roller provided on its inner surface are in sliding contact, sliding resistance increases during high-speed operation. Furthermore, with such a structure, it is impossible to change the amount of eccentricity between the cylindrical member and the rotor.

However, in the radial plunger pump of the present invention,
Since the cam ring is the guide ring 4 as described above, there are various effects described below.

First of all, since the guide ring 4 does not contribute in any way to defining the pump working chamber 23, there is a gap between the side end surface of the guide ring 4 and the housing 1, and the clearance between the side end surface of the guide ring 4 and the side housing 5. There is sufficient clearance between the Therefore, the guide ring 4 provided in the radial plunger pump has the effect of being able to rotate smoothly without being subjected to sliding resistance from the side end surfaces.

Second, since the outer ring 4b of the guide ring 4 is cylindrical, when the guide ring 4 is moved to change the amount of eccentricity of the guide ring 4, the outer ring 4b moves while rolling on the inner peripheral surface of the housing 1. I can do it. Further, as described above, a sufficient clearance is provided at the side end surface of the guide ring 4.

Therefore, the amount of eccentricity of the guide ring 4 within the housing 1 can be easily changed, and at the same time, the responsiveness during movement is very good. According to experiments conducted by the present inventors, when this amount of eccentricity is changed, the response time is several meters.
The range was from sec to several rounds msec. The response time here is the period from when a signal for shifting the eccentricity of the guide ring 4 is input until when the discharge flow rate of the working fluid discharged from the pump completely changes.

Thirdly, the tip of the plunger 3 is only R-shaped and has no other protrusions, so even when the pump is operated at high speed, there is no resistance from the fluid inside the pump. The force is extremely small. Further, since the inner ring 4a of the guide ring 4 rotates on the circumference around the center O' of the guide ring 4, it receives almost no resistance from the fluid inside the pump. Further, since the revolution speed of the fluid 4c is approximately half the rotation speed of the inner ring 4a, the resistance received from the fluid is small. In other words, there is no problem with the resistance generated by providing the guide ring 4. Therefore, the provision of the guide ring 4 has the effect of reducing the sliding resistance that the tip of the plunger 3 receives from the housing 1. At the same time, there is an effect that the resistance that the tip of the plunger 3 receives from the fluid inside the pump can be reduced.

Next, a second embodiment will be explained with reference to FIGS. 5 to 7.

In the second embodiment, an annular groove 104 is provided on the outer periphery of the outer ring 4b of the guide ring 4 of the first embodiment.

This ring groove 104 is a space 105 formed by the housing 1 and the outer ring 4b when the guide ring 4 is moved at high speed.
(Fig. 6) is intended to reduce the resistance when the fluid filled in the outer ring 4b is pushed out to the outer ring 4b. In this embodiment, the fluid in the space 105 flows between the housing 1 and the ring groove 104.
Since the fluid flows into the space 106 on the opposite side through the gap formed in the space 105, the displacement resistance of the fluid in the space 105 can be made considerably small. Furthermore, if the shape of the annular groove 104 is made to have a fin shape on the 10th la 51 and the 20th la 61 as shown in FIG. 7, the rotation (skinny) of the first control piston 50 and the second control piston 60 can be reduced. It can be prevented. Therefore, the flat surface provided on the housing 1 as shown in FIG. 4 of the first embodiment is unnecessary, and the drilling process becomes easy. Also, the first shaft 52 supporting the 10th shaft 51, the 20th
- The second shaft 62 supporting the ring groove 10
4, it is always maintained parallel to the rotation axis of the guide ring 4. Therefore, the quantity rollers 51, 52 can be easily rotated.

Next, a third embodiment will be described based on FIG. 8.

In this embodiment, the annular groove 104 shown in the second embodiment is replaced with a rectangular groove 104' corresponding to the side end surfaces of the 10th lug 51 and the 20th lug 61.

Further, the inner surface of the housing 1 with which the outer periphery of the outer ring 4b comes into contact is provided with at least a protrusion (not shown) corresponding to the rectangular groove 104', and the guide ring 4 is attached to this protrusion, the tenth ring 51. It is supported at at least three points on the 20th line 61. When the annular groove is made into a rectangular groove 104' in this way,
The movement of the guide ring 4 in the left and right directions in the figure is restricted. Therefore, the clearance between the side end surface of the guide ring 4 and the housing 1 etc. can be made extremely large.

Further, the resistance received from the fluid within the pump when the guide ring 4 moves can be further reduced, and a variable displacement pump with high speed responsiveness can be achieved.

Next, a fourth embodiment will be described based on FIG. 9.

In this embodiment, a needle roller 4 cl is used instead of the steel ball 4 c that is the wheeled member of the guide ring 4 .

Further, a ball 261 is used instead of the first roller 51 and the twentieth roller 61. Note that the control piston 260 corresponds to the first control piston 50 and the second control piston 60 described above. 204 is an R-shaped groove corresponding to the ball 261, and corresponds to the annular groove 104 described above. A groove 205 corresponding to the R shape of the tip of the plunger 3 is formed on the inner peripheral surface of the inner ring 4a. Therefore, the tip of the plunger 3 reliably and smoothly slides on the inner peripheral surface of the inner ring 4a of the guide ring 4. With such a configuration, the structure can be made even simpler than the above-mentioned embodiment.

Next, a fifth embodiment will be explained based on FIG. 10.

In this embodiment, a reinforcing ring 110.11 having an inner thickness of about several cranes is attached to the outer periphery of the outer ring 4C of the guide ring 4 of the first embodiment.
1. This reinforcing ring 110, 111
It is preferable that the material has a large Young's modulus. In the figure, 114 is a groove formed by the two reinforcing rings 110 and 111, and the annular groove 104 shown in the above-mentioned second embodiment
The guide ring 4 is provided to prevent deformation of the guide ring 4.According to the experiments of the present inventors, although a general bearing according to the JIS standard is used as the guide ring 4, the discharge pressure from the pump When high pressure is applied to guide ring 4
is deformed by about 0.5 m. This deformation is due to the force received from the plunger 3 during the compression stroke, and at this time the guide ring 4 assumes an elliptical shape. Here, if the reinforcing ring is provided, the deformation of the guide ring 4 provided with the reinforcing ring 110, 111 can be made extremely smaller than that of the guide ring 4 without the reinforcing ring.

Next, other shapes of the guide ring 4 will be explained based on FIG. 11.

In (a) and (b), the reinforcing rings 110 and 111 described in the fifth embodiment are integrated with the inner ring 4a and outer ring 4b of the guide ring 4. These do not have any strength problems and can have a simple structure, making it easy to assemble the pump. 4d corresponds to reinforcing rings 110 and 111.

(In C1, two rings 4d corresponding to reinforcing rings are integrally formed on the outer ring 4C, and the rectangular groove between the two rings 4d corresponds to the ring groove 104 shown in the above-mentioned second embodiment. The inner ring 4b has a radius corresponding to the tip of the plunger 3.
A shaped groove is formed.

(dl is a ring 4d corresponding to the reinforcing ring on the inner ring 4a.
are integrally formed.

In (e), an angular ring groove is provided in the outer ring 4.b, and in this case, the 10th ring 51. The 20th-ra 61 is shaped like a solo bread ball.

In (f), a ring 4d corresponding to a reinforcing ring is integrally formed on the inner peripheral surface of the outer ring 4b.

(The horse chestnut uses a needle roller 40' instead of the steel ball 4C, and a ring 4d corresponding to a reinforcing ring is integrally formed on the inner ring 4a.
- 4d is a ring corresponding to the reinforcing ring.

In addition, (hl is a reinforcing ring 11 on the inner ring of a commercially available bearing.
(1) is an example in which a reinforcing ring is fitted into the outer ring of a commercially available bearing, and (h) and (i) can be lowered in cost compared to (al to (g)) by using a commercially available bearing.

As explained above, the guide ring 4 only needs to have an inner ring 4a having various shapes, an outer ring 4b, and rolling elements interposed therein.

Next, another variable capacitance method will be described as a sixth embodiment based on FIG. 12. - In the first embodiment there are two first . Second control piston 50.6
0 was used, but in reality, a horizontal component force (a force that attempts to reduce the amount of eccentricity) is acting on the guide ring 4 according to the pressure applied to the piston, so control can be easily performed even without the second control piston 60. It is possible. However, since this horizontal component force fluctuates at a frequency depending on the number of pistons, it causes slight vibrations in the guide ring 4. Therefore, in order to suppress this slight vibration, in this embodiment, the pressure pin 160 is held together by a spring 164, and the guide ring 4 is sandwiched therebetween. 169 is a protrusion on the right end surface of the kya knob 63;
The spring 164 is positioned. The pressure pin 160 has a swinging structure, and the pressure pin 160 and the outer ring 4b of the guide ring 4 do not slip, and the pin 160 follows the movement of the outer ring 4b. By adopting such a structure, capacity control becomes possible with a simpler structure.

Furthermore, a leaf spring 360 as shown in FIG. 13 may be used. This leaf spring 360 corresponds to the pressure pin 160 and can have the simplest structure.

〔Effect of the invention〕

As described above, the present invention provides a cam ring with an inner ring, an outer ring,
Since the guide ring is constituted by a wheeled body interposed therebetween, it is possible to reduce the sliding resistance of the sliding surface with the plunger housing, and at the same time, reduce the fluid resistance that the plunger receives from the fluid inside the pump. That is, the excellent effect of enabling smooth high-speed operation of the pump is exhibited. Also, when controlling capacity,
A highly responsive variable displacement pump can be provided. Furthermore, since each sliding surface rolls and slides, the problem of wear on the tip of the plunger, etc. is also eliminated, and the durability of the pump can be improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a first embodiment of the present invention, FIG. 2 is a sectional view taken along line T in FIG. 1, and FIG.
4 is a partial sectional view taken along line N-IV in FIG. 3, FIG. 5 is a partial vertical sectional view showing the second embodiment, and FIG. 6 is a partial sectional view taken along line N-IV in FIG. 7 is a sectional view taken along the line ■-■ in FIG. 6, FIG. 8 is a sectional view of main parts showing the third embodiment, and FIG. 9 is a sectional view showing the fourth embodiment. A sectional view of the main part, Fig. 1θ is a sectional view of the main part showing the fifth embodiment, Fig. 11 (
a) to FIG. 11(1) are partial sectional views showing the shape of the guide ring, and FIGS. 12 and 13 are main part sectional views showing other embodiments. 1... Housing, 2... Rotor, 21... Cylinder hole, 3... Plunger, 4... Guide ring,
4a... Inner ring of the guide ring, 4b... Outer ring of the guide ring, 4c, 4c'... Steel balls that are rolling elements of the guide ring. Needle roller, 4d...ring 9L 50.60.
...a first piston and a second control piston that are variable means;
51.61.261... 10th-ra, 20th-ra, ball, 104... which are rolling elements provided in the variable means.
Ring groove, which is the groove of the outer ring of the guide ring, 11O, 111
...Reinforcement ring. Representative Patent Attorney Takashi OkabeFigure 7Figure 10Figure 11

Claims (6)

[Claims] (1) A housing that forms the outer shape of the pump, a rotor that is supported inside the housing and rotates, a plurality of cylinder holes drilled radially in the rotor, and a plurality of cylinder holes that are slidably inserted into the cylinder holes. The plunger is composed of an inner ring having an inner surface that the tip of the plunger contacts, an outer ring that contacts the inner surface of the housing, and rolling elements that are interposed between the inner ring and the outer ring. 1. A variable displacement pump comprising: a guide ring provided centrally; and variable means provided in contact with the guide ring for changing the amount of eccentricity between the rotor and the guide ring. (2) The variable displacement pump according to claim 1, wherein the variable means is provided with a control member having a rolling element that comes into contact with the outer ring of the guide ring. (3) The variable displacement pump according to claim 2, wherein a groove is provided along the outer periphery of the guide ring. (4) The variable displacement pump is provided on the inner peripheral surface of the inner ring of the guide ring. (5) The variable displacement pump according to claim 4, wherein a reinforcing ring is provided on the outer periphery of the guide ring to supplement the strength of the guide ring. (6) The variable displacement pump according to claim 4, wherein a ring portion for supplementing strength is integrally formed in at least one of the inner ring and the outer ring of the guide ring.