JPS6124713Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vane pump, and more particularly, to a vane pump suitable for use in a so-called power steering device for reducing the steering force of an automobile, for example.

Generally, this type of vane pump includes a rotor having a plurality of vanes that are slidably incorporated into radially formed slits, and a cam ring having a substantially elliptical cam surface that surrounds the circumferential surface of the rotor. , a pressure plate and a side plate are arranged on both sides of the rotor and the cam ring and form a pump chamber together with the cam ring, and as the rotor rotates, the vanes in the slit reciprocate and their outer ends enter the pump chamber. A pump operation is performed by protruding and slidingly contacting the cam surface. Such a vane pump has advantages such as a relatively simple structure, low noise operation, low cost, reliable operation, and low possibility of failure. This is particularly useful in cases where only a very small discharge amount is required, such as in power steering systems, for example.

However, on the other hand, the vane pump having the above-mentioned configuration has a problem in that the ambient temperature at the time of startup is low and it is difficult to discharge hydraulic fluid when the pump rotates at low speed. In other words, the vane performs a pumping action by being pressed against the cam surface by the centrifugal force caused by the rotation of the rotor and the pressure oil on the discharge side applied to the base end of the vane, but due to the low temperature, the viscosity of the oil decreases. It is large, and there is insufficient centrifugal force at low speed rotation,
This is because the movement of the vane is obstructed. and,
In order for the pump to begin discharging oil, the rotor must be rotated at a rotation speed above a certain level where the centrifugal force is strong enough to overcome the viscous resistance of the oil and the sliding resistance within the vane slit. The colder and more viscous the oil, the higher this initial rotation speed.

Therefore, when this type of vane pump is used at particularly low temperatures, the vane is pressed against the cam surface and the pump is operated after the initial rotation speed is exceeded, while the pump is warmed up and the viscosity of the oil is reduced. and start discharging oil. and,
Since this start of discharge occurs at a high rotational speed, a strong impact pressure is generated at that time.

For this reason, when the above-mentioned vane pump is used in a power steering system, especially in a cold region, its operation will be delayed for a certain period of time after the engine starts, resulting in poor startability.Furthermore, impact pressure will be generated at the start of its operation, which causes This acts as a strong impact on the handle, which lacks functional reliability and is also undesirable from a safety standpoint.

In order to solve this difficulty when starting a pump, there has been a conventional pump that incorporates a spring at the bottom of each slit in the rotor so that the vane is always pressed against the cam surface, but this method is cumbersome to assemble. This is especially difficult with small pumps.
Additionally, when the vane is pushed into the slit by the cam surface, the force acting on the spring is constantly acting on the spring, making it difficult to maintain its durability. There was a problem.

In addition, Japanese Patent Publication No. 54-37682 discloses that when the viscous resistance of oil is large due to low temperature and the rotational speed is low, hydraulic pressure is forcibly generated to press the vane against the cam surface, and the pump operation is quickly started. A structure is disclosed in which short-circuit passages are formed in plates disposed on both sides of the rotor to guide the hydraulic pressure generated when the vane on the discharge side is pushed into the slit to the base of the vane on the suction side so as to start the rotor. However, in this configuration, the discharge side and suction side communicate through a passage of the same width, so there is little change in the pressure oil, and especially if the width is too wide, the above-mentioned vane pressing effect cannot be expected. . On the other hand, if the passage width is narrowed to increase the change in pressure oil, the pressing force acting on the suction side vane will become larger than necessary, and especially during normal high-speed rotation, the vane will be pressed against the cam surface more than necessary. The energy loss is large, and there is also the problem that the durability of the vane is poor due to this.

The present invention was developed in view of the above circumstances, and it is designed to provide a slit in the suction side area of a pair of pump chambers formed on the outer circumferential portion of the rotor on both long-diameter ends of the cam surface in the cam ring. A suction-side arcuate groove that communicates the bottom to the pump discharge-side pressure chamber, and a discharge-side arcuate groove that communicates the bottom of the slit in the discharge-side region are formed in at least one of the plates disposed on both sides of the rotor. and the suction side and discharge side arcuate grooves corresponding to the respective pump chambers are communicated with each other by communication grooves having a throttling action formed at positions corresponding to the bottom of the slit on both ends of the cam surface in the major diameter direction. On the other hand, with a simple configuration in which the arcuate grooves corresponding to the other pump chambers located at both ends in the short diameter direction of the cam surface are in a non-communicating state, when the pump is started,
Even when the ambient temperature is low and the rotation speed is low, the vane can reciprocate reliably and immediately send out fluid, providing excellent startability.
Furthermore, the present invention provides an inexpensive vane pump that does not affect the operational performance of the pump and can be expected to operate smoothly.

Hereinafter, the present invention will be explained in detail using embodiments shown in the drawings.

Fig. 1 shows an embodiment in which the vane pump according to the present invention is applied to an oil pump used in a power steering device. To briefly explain the outline of the pump in the figure, numerals 1 and 2 are pump housings divided into two parts. , these pump housings 1,
A pressure chamber 4 housing a pump body 3, oil passages 5, 6, 7, etc. are formed within the pump 2. Reference numeral 8 denotes a drive shaft supported by the housing 1, one end of which faces into the pressure chamber 4, and a pulley 9 that receives rotational force from the automobile engine by a V-belt fixed to the other end. Reference numeral 10 denotes a flow control valve for controlling the flow rate flowing through the hydraulic circuit so that a constant flow of hydraulic oil can be supplied at all times, and prevents the oil pressure in the pressure chamber from rising above the adjustment pressure due to steering resistance. It is equipped with a relief valve 10a. Note that 11 is an outlet passage member, and discharged hydraulic oil is guided to a power steering body (not shown). Further, 12 is an oil tank, and 12a is a casing forming this.

Reference numeral 13 denotes a rotor constituting the pump body 3, and this rotor 13 is fixed to one end of the drive shaft 8 by spline fitting. This rotor 13 has a plurality of slits 14 (in this example, 10 slits are provided) formed radially at equal intervals in the circumferential direction.
A vane 15 is supported in each of the vanes 4 so as to be slidable in the radial direction. The bottom of the slit 14 is formed in the shape of a circular hole, and is configured to guide pressure oil on the discharge side and push out the vane 15 in the radial direction. A cam ring 16 is arranged to surround the rotor 13, and a cam surface 16a having a substantially elliptical shape is formed on the inner periphery of the cam ring. 1
Reference numerals 7 and 18 designate side plates and pressure plates that are arranged on both sides of the rotor 13 and the cam ring 16 and form a pair of pump chambers on the outer peripheral portion of the rotor 13 on both ends of the cam surface 16a in the long diameter direction inside the cam ring 16; Both plates 1
A suction hole 19 and a discharge hole 20 are formed in the plates 7 and 18, respectively, and these plates 17 and 18 and the cam ring 16 are connected by a pin 21 for positioning in the rotational direction. Note that the pressure plate 18 is provided on the flow control valve 10 side.
2 to the right side in the figure, and thereby the cam ring 16 and the side plate 17 are pressed against the housing 1 side. Reference numeral 23 denotes a pressure guiding hole for guiding pressure oil on the discharge side to the bottom of the slit 14 corresponding to the suction side vane 15 of the rotor 13. In addition, 19a and 20a are suction holes 19
and a groove provided in the plate on the opposite side corresponding to the discharge hole 20.

In such a configuration, the driving force from the engine is transmitted to the drive shaft 8 and the rotor 13
When the rotor 13 rotates, ten vanes 15 incorporated in the rotor 13 are pressed against the cam surface 16a of the cam ring 16 by centrifugal force and pressure oil, and reciprocate in the slit 14 according to its shape. Then, while the rotor 13 rotates half a rotation, a pair of adjacent vanes 1
5 and cam ring 16 and both plates 17, 18
During the period in which the volume of the space defined by the pump increases, the hydraulic fluid sucked in is pressurized and discharged from the discharge hole 20 into the pressure chamber 4 to perform a pump operation. That is, passages 5 and 6 are connected from the oil tank through the inlet part.
The hydraulic oil led to the suction hole 1 of the pump body 3
9, and after being pressurized, it is led to the pressure chamber 4 from the discharge hole 20, and further passes through the throttle 7a, the passage 7, and the outlet passage member 11, and is supplied to a power steering device (not shown).

Note that when the rotational speed of the pump increases as the engine rotational speed increases, more hydraulic oil is discharged than necessary, but this is controlled by the flow control valve 10, so that the amount supplied from the pump is constant. is maintained. In addition, the pressure increase in the hydraulic circuit due to operation of the power steering device is controlled by the relief valve 10a.
absorbed by.

Now, according to the present invention, in the vane pump having the above-mentioned configuration, a pair of pump chambers 30A, 30 are disposed on both sides of the rotor 13 together with the cam ring 16.
As shown in FIG. 2 to FIG.
discharge-side arcuate grooves 31A, 31B that communicate with the bottom of the slit 14 in the discharge-side region corresponding to the discharge side;
Suction side arcuate grooves 32A and 32B are formed which communicate with the bottom of the slit 14 in the suction side region and communicate with the pressure chamber 4 on the pump discharge side via the pressure guiding hole 23, and furthermore, these two pairs of discharge side and Suction side arcuate grooves 31A, 32A; 31B, 32B corresponding to the same pump chambers 30A, 30B, respectively; communication grooves 33A, 33B having a restricting action formed at positions corresponding to the bottoms of the slits 14;
It is configured to communicate through.

And, by having such a configuration,
When the vane pump is started, the vanes are made to work quickly and reliably even when the ambient temperature is low and the rotational speed is low. To explain this in detail, the above-mentioned discharge side arcuate groove 31 on the pressure plate side
A, 31B usually need to be communicated with the pressure chamber 4 on the pump discharge side, but in the present invention, the arcuate grooves 31A, 31B on the discharge side are connected to the communication grooves 33A, 33B, and the arcuate grooves 32A, 32B on the suction side ( The vane 15 is pushed into the slit 14 by the cam surface 16a, and the vane 15 is pushed into the slit 14 by the cam surface 16a. The oil pressure in 31A, 31B is set to a high pressure state, and its outflow is temporarily restricted by using the throttling action of communication grooves 33A, 33B. Vane 1 inside the slit 14
5 into the pump chambers 30A, 30B. That is, the communication groove 33A,
The pressure oil flowing inside 33B not only has a faster flow rate, but also has a higher pressure in the arcuate grooves 32A and 3 on the suction side.
Higher than 2B. Therefore, as the rotor 13 rotates, the vanes 15 in the slits 14 corresponding to the communication grooves 33A and 33B are connected to the pump chamber 30.
It acts as a force in the direction of protruding toward the A and 30B sides.
This is because the internal pressure in the pump chambers 30A, 30B is approximately the same as that in the pressure chamber 4 on the pump discharge side, whereas the internal pressure in the communication grooves 33A, 33B is higher than this, resulting in a pressure difference.

The operation is briefly explained using Fig. 2.
When the rotor 13 rotates and the centrifugal force causes the vanes 15 to protrude to the position indicated by the dashed line in the figure, they reach the pump discharge side region and are successively pushed into the slit 14 by the action of the cam surface 16a. As a result, the pressure in the bottom of the slit 14 and the discharge side arcuate grooves 31A, 31B increases to a certain extent, and when this pressure oil flows to the communication grooves 33A, 33B, the rotation of the rotor 13 causes the pressure oil to flow into the communication grooves 31A, 31B.
It acts on the vanes 15 in the slits 14 corresponding to 3A and 33B, and causes them to sequentially protrude into the pump chambers 30A and 30B as shown by arrows in the figure. The more the vane 15 protrudes, the more the discharge side arcuate groove 3
The pressure inside 1A and 31B also increases, and when this is reversed, the vane 15 is projected until it comes into contact with the cam surface 16a, resulting in a normal operating state. And at this time,
The amount of pressure oil discharged from the pump chambers 30A and 30B is
The discharge is performed sequentially depending on the amount of protrusion of the vane 15, and the complete amount of ejection is achieved when the amount of protrusion of the vane 15 reaches the maximum.

Therefore, according to the above-mentioned configuration, when the vane pump is started, the movement of the vane 15 is made using the pressure oil caused by pushing the vane 15 in addition to the centrifugal force.
Moreover, it works effectively even at low rotational speeds,
It overcomes the viscous resistance of oil and the sliding resistance of the vane 15 in the slit 14, has good startability, and can perform pump operation quickly and reliably.

Here, it should be noted that the communication grooves 33A and 33B according to the present invention are connected to each pump chamber 30.
It is provided between arcuate grooves 31A, 32A and 31B, 32B on the discharge side and suction side corresponding to A, 30B, and does not communicate the arcuate grooves on the adjacent pump chambers 30A, 30B. That is, even if the arcuate grooves 31A, 32A; 31B, 32B provided for the pair of pump chambers 30A, 30B are all made to communicate with each other, there is no effect on startability;
Since the pressure oil in 1B is dispersed, the force acting on the vane is weakened, resulting in poor startability. Furthermore, each arcuate groove 31A, 31B; 32A, 32B
In order to ensure a pressure increase in the discharge side arcuate grooves 31A and 31B while all of them are communicated with each other through a communication groove, a communication groove having a cross-sectional area approximately half or less than that of the communication grooves 33A and 33B according to the present invention is required. This requires processing with strict processing accuracy, which poses a major practical problem. especially,
The communication grooves 33A, 33B require a certain cross-sectional area in order to communicate the discharge side arcuate grooves 31A, 31B to the pump discharge side and prevent the vane 15 from dancing when the pump is in use. In order to form a communication groove with such a delicate cross-sectional area, it is necessary to adopt a structure that is as easy to process as possible, and the present invention satisfies this requirement.

In addition, when the pump is used, the pressure oil that becomes high pressure in the arcuate grooves 31A and 31B on the discharge side flows through the communication groove 33.
A, 33B to the suction side arcuate grooves 32A, 32
B, a certain amount of acting force is generated by the pressure oil on the vanes 15 in the slits 14 corresponding to the communication grooves 33A, 33B;
If the throttling action of 3B is set to be effective only at the time of starting, there will be no problem with the pump function.

Therefore, if the above-mentioned pump is used in a power steering device, the power steering can be operated almost at the same time as the engine starts, increasing its functional reliability and without generating harmful shock pressure. , it is also excellent in terms of safety.

Further, according to the present invention, arcuate grooves 31A, 32A; 31B, 32B on the discharge side and suction side are provided in the plates 17, 18 disposed on both sides of the rotor 13, and these are communicated with each other through the communication grooves 33A, 33B. It has an extremely simple structure, and each groove can be easily formed by pressing or sintering, which has the advantage of having little effect on the manufacturing process of the pump.

In the above-described embodiment, both the side plate 17 and the pressure plate 18 provided on both sides of the rotor have arcuate grooves 31 on the discharge side and the suction side.
A, 32A; 31B, 32B and a case where communication grooves 33A, 33B are provided to communicate these are provided, but
The present invention is not limited to this, and only one of the plates may be used.In short, the pressure oil generated by the vane pushing on the discharge side is communicated to the suction side through the throttle part, and this is communicated to the pressure chamber on the pump discharge side. Any configuration is sufficient as long as it allows

Further, the portion where the pressure on the discharge side is applied to the vane does not necessarily have to be on the communication grooves 33A, 33B, and the configuration may be such that the acting force by pressure oil is applied to the vane at a portion closer to the discharge side.
That is, the flow of pressure oil generated on the discharge side may be temporarily regulated between the flow of pressure oil and the suction side by a throttling action, and a pop-out force may be applied to the vane here.

Further, the vane pump according to the present invention is not limited to the oil pump for power steering equipment described in the embodiment, and its structure is not specified, and any vane pump having a well-known structure can be applied. It is.

As explained above, according to the vane pump according to the present invention, the pressure oil generated in the discharge side region of the pump chamber is guided to the suction side region side through the communication groove having a throttling action, and the communication groove Since the pressing force from pressure oil is applied to the vanes at the pump, even when the ambient temperature is low and the rotational speed is low, the vanes reciprocate reliably and immediately discharge fluid. It has excellent start-up performance, and under normal conditions, it does not impair its performance in any way, and you can always expect smooth pump operation.It is also simple in structure, easy to process, and cost-effective. The effect is great.

[Brief explanation of the drawing]

The drawings show one embodiment of the vane pump according to the present invention, in which Fig. 1 is a vertical cross-sectional view showing the overall schematic configuration, Fig. 2 is an enlarged view of the main parts, and Fig. 3 a and b show the side plate and plate. FIG. 4 is a plan view showing the inner surface of the shear plate, and FIG. 4 is an exploded perspective view showing the pump body. 3... Pump body, 4... Pump discharge side pressure chamber, 13... Rotor, 14... Slit, 15...
... Vane, 16 ... Cam ring, 17 ... Side plate, 18 ... Pressure plate, 30
A, 30B... pump chamber, 31A, 31B... discharge side arcuate groove, 32A, 32B... suction side arcuate groove,
33A, 33B...Communication groove.

Claims (1)

[Scope of utility model registration request] A rotor comprising a plurality of vanes assembled into slits, a cam ring having a substantially elliptical cam surface surrounding the circumferential surface of the rotor, and a cam ring disposed on both sides of the rotor and the cam ring inside the cam ring. In a vane pump comprising a pressure plate and a side plate that form a pair of pump chambers on the outer circumferential portion of the rotor on both ends in the long diameter direction of the cam surface, at least one inner surface of the two plates is provided with a pressure plate that corresponds to each pump chamber. A suction-side arcuate groove that communicates the bottom of the slit in the suction-side region to the pressure chamber on the pump discharge side, and a discharge-side arcuate groove that communicates the bottom of the slit in the discharge-side region, and A communication having a throttling action is formed between a suction side arcuate groove and a discharge side arcuate groove formed corresponding to the chamber at a position corresponding to the bottom of the slit on both ends in the major diameter direction of the cam surface. A vane pump characterized in that a discharge-side arcuate groove and a suction-side arcuate groove, which are in communication with each other through a groove, and which are located on the short-diameter end side of the cam surface are in a non-communication state.