JPH07259754A - Variable displacement type pump - Google Patents

Abstract

PURPOSE:To reduce the generation of a drive hose power and to improve startability at a low temperature time. CONSTITUTION:A pump chamber 18 is formed in a body 11 at the outer peripheral part of a rotor 15 with a vane 15a by using a cam ring 17, which is fitted in. First and second fluid pressure chambers 34 and 35 in which a fluid pressure is guided according to a flow rate on the delivery side of a pump are formed to the outside of the cam ring. An arcuate groove part 50 on the suction side and the delivery side of a pump is formed in correspondence with the base end part of a slit groove 15b for containing a vane of a side wall part making contact with a surface part on the cam ring side. The slit groove and the groove part are formed in respective positions corresponding to a region 18A on the suction side and a region 18B on the delivery side. The arcuate groove part 50 on the suction side of a pump is formed closer to the starting end of the region on the suction side and in a range of approximate 2/3 thereof. The arcuate groove part 51 on the delivery side of a pump is formed fronting on approximate 1/3 of the region on the suction side.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a variable displacement vane pump used in a pressure fluid utilizing device such as a power steering device for reducing the steering force of an automobile.

[0002]

2. Description of the Related Art As a pump for a power steering apparatus, a displacement vane pump which is directly driven by an automobile engine has been generally used. However, in such a displacement pump, since the discharge flow rate is increased / decreased according to the engine speed that is the drive source, a large steering assist force is generated when the vehicle is stopped or traveling at low speed, and the steering assist force is generated at high speed traveling. It has a characteristic that is contrary to the power steering device of making it smaller.

Therefore, as such a pump,
A flow rate control is used to control the discharge flow rate when the number of rotations is high, and a discharge flow rate that ensures the required steering assist force is used even when the vehicle is traveling at low speeds. A valve is required. Therefore, in such a pump, the number of constituent components is increased, the structure is complicated, and the passage structure is also complicated, so that the overall size and cost are inevitable.

Further, when the flow rate control valve is used, a part or most of the discharge flow rate of the pump is returned to the tank side, so that the driving horsepower increases, energy loss increases, and the oil temperature further rises. There are also problems.

As a solution to such a problem in the displacement type, there is a variable displacement vane pump capable of gradually reducing the discharge flow rate as the number of revolutions increases, for example, Japanese Patent Laid-Open No. 53-130505. Kaisho 56-143383
Japanese Patent Publication No. 58-93978, Japanese Utility Model Publication No. 63-
Various proposals have been made in Japanese Patent No. 14078.

In such a variable displacement type pump, a flow rate control valve like that of a displacement type is not required, useless increase of driving horsepower is prevented, energy efficiency is excellent, and the return flow rate to the tank side is further improved. Therefore, the problem of oil temperature rise can be reduced, and problems such as leakage inside the pump and volumetric efficiency decrease can be prevented.

As such a variable displacement pump, for example, in Japanese Unexamined Patent Publication No. 56-143383, a cam ring is constructed so as to be movable within a pump casing.
Fluid pressure chambers that form a pair of control chambers are formed in the gap formed between the cam ring and the pump casing, and pressures before and after the orifice provided in the middle of the discharge passage are introduced to the respective chambers, and the pressure difference is applied to the cam ring. It is disclosed that the cam ring is directly actuated and the cam ring is appropriately moved against the urging force of the spring to change the volume of the pump chamber to appropriately control the discharge flow rate.

However, in such a pump, the cam ring is held so as to be linearly movable in the pump housing, and the cam ring is moved and displaced by the pressure difference on the downstream side on the orifice provided directly or indirectly in the discharge passage. Just
Since there are many constituent parts and fluid passages in each part of the pump, there are problems in terms of workability and assemblability, reliability in operation, and durability, and it is unrealizable.

The present applicant has previously proposed Japanese Patent Application No. 4-358801 as a solution to such a conventional problem. To briefly explain this, the variable displacement vane pump is eccentrically fitted so as to form a pump chamber with the outer peripheral portion of the rotor, and is arranged so as to be movable and displaceable in the pump body. It is equipped with a cam ring that is biased to maximize its capacity.
Further, by interposing a sealing means at a predetermined portion of the annular clearance space between the cam ring and the pump body, the first and second fluid pressure chambers for moving and displacing the cam ring in the pump body are formed. In addition, a switching valve that controls the fluid pressure supplied to the first and second fluid pressure chambers by being operated according to the discharge flow rate of the pressure fluid from the pump chamber is provided.

Further, in such a variable displacement pump, inside the cam ring, a portion corresponding to the base end portion of the vane accommodating slit groove of the rotor is provided on the side wall portion provided in contact with the side surface portions of the rotor and the cam ring. In the pump chamber formed on the outer peripheral portion of the rotor, arc-shaped groove portions corresponding to the pump suction side and the pump discharge side are formed respectively, and the fluid on the pump suction side and the pump discharge side corresponding to these arc-shaped groove portions, respectively. I try to introduce pressure.

According to this structure, the first and second fluid pressure chambers formed on both sides of the cam ring outer peripheral portion which is eccentric with respect to the rotor in the pump body are provided in accordance with the flow rate on the pump discharge side. By introducing a fluid pressure having a predetermined pressure difference from the operated switching valve into each chamber, the cam ring is oscillated and displaced in a predetermined direction, and as a result, the volume of the pump chamber formed between the cam ring and the rotor is changed. The flow rate of the fluid on the discharge side of the pump changes and is variably controlled.

Further, in the vane held in the rotor rotating in the cam ring so as to be able to move in and out, when the tip of the vane slides along the inner peripheral surface of the cam ring, the tip of the vane causes the pump in the pump chamber to move. When it is in either the discharge side area or the pump suction side area,
By applying approximately the same pressure that matches the pressure inside the pump chamber facing each vane tip, the sliding resistance of the tip of each vane to the inner peripheral surface of the cam ring is reduced, and sliding friction and wear occur. As a result, the driving horsepower can be reduced as compared with the case where a high-pressure pump discharge side pressure is applied to all of the vane base ends, which is conventionally common.

[0013]

According to the variable displacement pump having the above-described structure, the vane has a low pressure at the base end portion of the vane passing through the portion corresponding to the pump suction side region of the pump chamber. The high pressure pump discharge side pressure is applied to the vane in the area corresponding to the pump discharge side area, so the sliding resistance to the cam ring inner peripheral surface of the vane tip is reduced and the driving horsepower is low. Can be suppressed.

On the other hand, however, the pump having such a structure has difficulty in starting at low temperatures. That is, since the viscosity of the hydraulic oil is high at low temperatures, the vanes do not fly out only by the centrifugal force accompanying the rotation of the rotor,
The pressure on the pump discharge side does not rise. In the rotor vane corresponding to the pump suction side, since the pressure on the pump suction side continues to act, the vane does not easily fly out, and the vane popping out property, that is, the low temperature startability is poor, and as a result, the pump discharge side Since no pressure can be obtained, there is a problem in terms of startability when the engine temperature is low.

[0015] Such a problem leads to a problem that the steering wheel is heavy in a severe winter when it is used for a pump for a power steering apparatus of an automobile, for example, and some measures for solving such a problem are taken. Is desired.

The present invention has been made in view of the above circumstances, and it is possible to minimize the driving horsepower of the pump and reduce the oil temperature rise and the like, while improving the startability at low temperatures. The purpose is to obtain a positive displacement pump.

[0017]

In order to meet such demands, a variable displacement pump according to the present invention has a rotor having a vane rotatably arranged in a pump body and a rotor fitted around the rotor. Are formed to form a pump chamber, and first and second fluid pressure chambers are formed in the outer peripheral portion between the pump body and the pump body, and fluid pressure according to the flow rate on the discharge side of the pump is formed in the pump body. A possible cam ring, and a portion corresponding to the base end portion of the vane housing slit groove of the rotor in the side wall portion arranged in contact with the side surface portion of the cam ring, which are respectively in the suction side region and the discharge side region of the pump chamber. Equipped with corresponding arc-shaped grooves on the pump suction side and the pump discharge side into which the fluid pressures on the pump suction side and the discharge side are introduced, and the pump suction side arc-shaped groove starts suction on the pump suction side area. And forming a deviation, the pump discharge side arcuate groove portion, in which the leading end portion was formed so as to face up to the suction side region of the pump chamber.

The variable displacement pump according to the present invention is
The pump discharge side arcuate groove formed so as to reach the suction side region of the pump chamber is connected to the pump discharge side via the orifice portion.

Further, in the variable displacement pump according to the present invention, the arc-shaped groove portion on the pump suction side is formed in the pump suction side region over a range of about 2/3 from the suction start end, and the arc shape on the pump discharge side is formed. The groove is formed over the pump discharge side region including the remaining 1/3 range in the pump suction side region.

[0020]

According to the present invention, the first and second fluid pressure chambers formed on both sides of the outer peripheral portion of the cam ring, which is eccentrically fitted to the rotor in the pump body, correspond to the flow rate on the pump discharge side. A fluid pressure having a predetermined pressure difference is introduced to oscillate and displace the cam ring in a predetermined direction, thereby changing the volume of the pump chamber formed between the cam ring and the rotor and variably controlling the fluid flow rate on the pump discharge side. It becomes possible.

In particular, according to the present invention, in the vane in the pump suction side region, since the high pressure on the pump discharge side is applied to the base end portion of the vane near the discharge side, it operates at the low temperature start. Even if the viscosity of the oil is high, it is possible to cause the vanes to pop out, and the suction and discharge operations of the pump can be performed, so that the startability at low temperatures can be improved. Of course, in the vanes in the pump suction side region and the discharge side region other than that, substantially the same pressure is applied according to the pressure inside the pump chamber facing each tip, and the cam ring at the tip of each vane is acted. It becomes possible to reduce sliding resistance to the inner peripheral surface, eliminate sliding friction and wear, and reduce driving horsepower.

[0022]

1 to 4 show an embodiment of a variable displacement pump according to the present invention. In these drawings, in this embodiment, a vane type oil pump serving as a hydraulic pressure generation source of a power steering apparatus is shown. Will be described.

First, a vane type variable displacement pump, generally designated by reference numeral 10, is provided with a front body 11 and a rear body 12 constituting a pump body, as is apparent from FIGS. 1 and 3. This front body 1
1 has a substantially cup shape as a whole, and a storage space 14 for storing and arranging the pump component 13 therein is formed therein, and a rear body 12 is combined so as to close an open end of the storage space 14. It is integrated. It should be noted that the front body 11 has a drive shaft 16 for rotatably driving the rotor 15 as a rotor of the pump component 13 from the outside, and the bearing 1
6a, 16b, 16c (16b is the rear body 12 side, 1
6c is rotatably supported by a pressure plate 20 described later).

Reference numeral 17 has an inner cam surface 17a fitted and arranged on the outer peripheral portion of the rotor 15 having a vane 15a, and a pump chamber 18 between the inner cam surface 17a and the rotor 15.
The cam ring 17 forms a cam ring 17 that can be moved and displaced in an adapter ring 19 provided in a fitted state on the inner wall portion of the storage space 14 so as to change the volume of the pump chamber 18, as described later. It is located in. The adapter ring 19 is for holding the cam ring 17 in the housing space 14 of the body 11 so that the cam ring 17 can be displaced.

Reference numeral 20 is the rotor 15 and the cam ring 1 described above.
7 and an adapter ring 19 are pressure plates that are stacked in pressure contact with the front body 11 side of the pump cartridge, and the end surface of the rear body 12 is pressed against the opposite side surface of the pump cartridge as a side plate. The bodies 11 and 12 are integrally assembled into a required assembled state. Then, by these members, the pump component 13
Is configured.

Here, these pressure plates 20
The rear body 12, which is a side plate laminated on the cam ring 17 and the cam ring 17, is positioned in the rotational direction by a seal pin 21 (which will be described later) which also functions as a positioning pin and an appropriate rotation preventing means (not shown). It is assembled and fixed in one.

Reference numeral 23 denotes a pump discharge side pressure chamber formed on the bottom side of the storage space 14 of the front body 11 so as to apply the pump discharge side pressure to the pressure plate 20. Reference numeral 24 denotes a pump discharge side passage which is formed in a pressure plate 20 which guides the pressure oil from the pump chamber 18 to the pump discharge side pressure chamber 23.

Reference numeral 25 denotes a pump suction side formed in the rear body 12 so as to guide the pump suction side fluid from a suction port 26 (detailed illustration is omitted) provided in a part of the rear body 12 to the pump chamber 18. In the passage, this passage 25
Is a pump suction opening 2 that opens at the end surface of the rear body 12.
It is connected to the pump chamber 18 via 5a.

Reference numeral 28 denotes the pump chamber 18, the pump discharge side passage 24, the pump discharge side pressure chamber 23, and the pressure chamber 2
3 extending upward from the front body 11 to the passage hole 23a
The pump discharge side passage connected via
A metering orifice 29 is provided in the middle of the flow path, and a discharge port for supplying the pump discharge side fluid pressure to a hydraulic device such as a power steering device (not shown) (indicated by PS in the figure) is provided on the outer end side. Has been.

Reference numeral 30 is a switching valve which is disposed substantially orthogonally above the storage space 14 in the front body 11 and which moves and displaces the above-mentioned cam ring 17 with respect to the rotor 15 within the pump body 11 (adapter ring 19). The switching valve 30 has a pressure difference before and after the metering orifice 29 of the pump discharge side passage 28 in a valve hole 30a formed in the body 11 and a spring 3 therein.
Spool 3 with a relief valve that slides with an urging force of 1
Equipped with 2.

In FIG. 4, 29a and 29b are passages for introducing pressures before and after the orifice 29 into the valve hole 30a. Further, in the central portion of the valve hole 30a, a high pressure side passage 28b for guiding the fluid pressure from the pump discharge side passage 28 and a part of the pump suction side passage 25 are branched to guide the fluid pressure to the tank side. The low-pressure passages 25b are formed so as to be opened, and are selectively opened / closed in accordance with the movement of the spool 32 to introduce a fluid pressure to first and second fluid pressure chambers described later.

That is, in such a switching valve 30, one chamber (left chamber in FIGS. 1 and 4) 3 of the spool 32 is
The fluid pressure on the upstream side of the metering orifice 29 is introduced to the pump 2a through the pressure chamber 23 on the pump discharge side, the pump discharge side passage 28, and the passage 29a. Reference numeral 33 in the drawing denotes a plug for closing the valve hole 30a, which has a rod 33a for locking the position of the spool 32 moving leftward in the valve hole 30a at a position where the opening end of the passage 29a is not closed.

The other chamber of the spool 32 (see FIGS. 1 and 4)
A right side chamber 32b is provided with a spring 31, and fluid pressure on the downstream side of the metering orifice 29 is guided from the middle of the passage 28 reaching the discharge port 28a through the passage 29b.

Further, at a position aligned in the moving direction of the spool 32 at a substantially central portion of the valve hole 30a, the first and the first portions formed between the outer peripheral portion of the cam ring 19 and the adapter ring 19 on the body 11 side. 2 fluid pressure chambers 34, 35
The pressure guiding passages 36 and 37 (including the passage holes 36a and 37a of the adapter ring 19) formed through the body 11 and the adapter ring 19 are formed to be open. Reference numeral 34a in FIG. 1 is a groove portion for forming the first fluid pressure chamber 34 between the inner wall surface of the adapter ring 19 and the cam ring 17.

As is apparent from FIGS. 1 and 4, these passages 36 and 37 are provided in the pump discharge side passage 28 through the passage 29b or 28b or the pump suction opening by the movement of the spool 32. It is adapted to be selectively connected to the 25b side via a passage 25b.

On the other hand, reference numeral 40 in FIG. 1 denotes pump bodies 11, 1.
The cam ring 17 arranged so that it can be moved and displaced without
The coil spring 41 is a pressing member that urges the pump chamber 18 formed on the outer peripheral portion of the rotor 15 to have the maximum volume.
And a tubular presser plug 42.

The vane type variable displacement pump 10 described above has a configuration other than that described above which is well known in the art, and a detailed description thereof will be omitted.

In the variable displacement pump 10 having the above-described structure, the variable displacement pump 10 is fitted in an eccentric state so as to form the pump chamber 18 with the outer peripheral portion of the rotor 15, and is movable and displaceable in the pump bodies 11 and 12. Is disposed on the outer periphery of the cam ring 17 which is urged so that the volume of the pump chamber 18 is maximized.
By interposing seal pins 21 and 47 as sealing means at predetermined positions in the annular clearance space between the first and second fluid pressures, the cam rings 17 are oscillated and displaced in the pump bodies 11 and 12. A switching valve 30 is provided in which the chambers 34 and 35 are formed and which is operated according to the discharge flow rate of the pressure oil from the pump chamber 18 to control the fluid pressure supplied to the first and second fluid pressure chambers 34 and 35. Has been.

Here, in order to divide the above-mentioned annular clearance space between the cam ring 17 and the adapter ring 19, in this embodiment, as apparent from FIGS. 1 and 2, the annular clearance space is divided into left and right. A second seal pin 47, which is positioned above and below so as to be divided and is installed through an elastic member in a groove formed in the sliding contact surface between the first seal pin 21 and the cam ring 17, which also functions as a positioning pin. Is provided.

Then, the space on the left side is provided with the first fluid pressure chamber 34.
The chamber 34 is connectable to the left chamber 32a of the switching valve 30 or the pump suction side via the fluid passages 36a, 36. The space on the right side is the second fluid pressure chamber 35, and this chamber 35 is used as the fluid passages 37a, 3a.
7 through the spool 32 at the central portion of the switching valve 30.
It is configured to be selectively connectable to the pump discharge side or the pump suction side according to the movement of the.

Further, the pressing member 4 having the above-mentioned cylindrical shape.
As is clear from FIG. 1, 0 is configured so that the cam ring 17 is always pressed leftward in FIG. 1 by the coil spring 41. The pressing member 40 may have any shape as long as it can press the cam ring 17 and can always press the inner volume of the pump chamber 18 to the maximum.

According to the above construction, when the pump 10 is started, the inner volume of the pump chamber 18 between the cam ring 17 and the rotor 15 is located on one side of the housing space 14 of the body 11 as is apparent from FIG. The coil spring 41 of the pressing member 40 is biased so as to maximize the pressure. At this time,
As is apparent from FIG. 1, the switching valve 30 is in a state in which the first fluid pressure chamber 34 is connected to the pump suction side and the second fluid pressure chamber 35 is connected to the pump discharge side via the passage 28b.

When the pump rotational speed is gradually increased and driven, the switching valve 30 is driven by the differential pressure due to the fluid pressure on the orifice 29 on the pump discharge side and on the downstream side, which is obtained in proportion to the pump rotational speed. The spool 32 of the pump is operated in a switching manner, whereby the pump discharge side and the pump suction side are selectively connected to the first fluid pressure chamber 34 and the second fluid pressure chamber 35 on both sides of the cam ring 17, whereby the rotor 15 The cam ring 17 which is eccentric with respect to the coil spring 41
Against the above, the pump chamber 18 is moved and displaced in the direction in which the internal volume decreases (see FIG. 1).

At this time, by the switching operation by the spool 32 of the switching valve 30 according to the magnitude of the fluid flow rate on the pump discharge side, the pump discharge side is positioned opposite to the first fluid pressure chamber 34. The pump suction side is appropriately connected to the second fluid pressure chamber 35 that is present, whereby the cam ring 17 is appropriately moved and displaced depending on the operating state of the switching valve 30, and as a result, the cam ring 17 is discharged from the pump chamber 18 whose internal volume is changed. The flow rate control can be performed in a required state, and it becomes possible to feed the power steering apparatus PS at a predetermined flow rate.

In particular, according to the above-described structure, the switching valve 30 is controlled to be switched by the differential pressure generated in the metering orifice 29 by the pump discharge amount which increases and decreases with the pump rotation speed, whereby the cam ring 17 is coiled. Four
It can be moved and displaced against the urging force of No. 1 or in accordance with this urging force. As a result, the internal volume of the pump chamber 18 is variably controlled, and the discharge amount from the pump is shown in FIG. 5, for example. As described above, it is possible to perform control so as to obtain a desired characteristic by balancing the pump rotation speed.

The characteristic curve shown in FIG. 5A is
The characteristic of the pump discharge flow rate with respect to the pump rotation speed is shown. Further, (b) of the same figure shows the eccentric state of the cam ring 17 with respect to the pump rotation speed, and (c) of the same figure shows the discharge amount (of the rotor 15) peculiar to the pump with respect to the eccentric state of the cam ring 17. The discharge amount per one rotation) is shown.

According to the above-described structure, the first and second fluid pressure chambers 34 formed on both sides of the outer peripheral portion of the cam ring 17, which is eccentrically fitted to the rotor 15 inside the pump bodies 11 and 12, 35, it is possible to introduce a fluid pressure having a predetermined pressure difference into the respective chambers 34, 35 by the switching valve 30 which is operated according to the magnitude of the flow rate on the pump discharge side, whereby the cam ring 17 is By moving and displacing in a predetermined direction, as a result, the internal volume of the pump chamber 18 formed between the rotor 15 and the rotor 15 can be changed, and the fluid flow rate on the pump discharge side can be variably controlled to a desired state. .

In particular, in the present embodiment, the cam ring drive control is performed in which the displacement of the cam ring 17 for performing the above-mentioned flow rate control due to the swing around the seal pin 21 is switched by the differential pressure before and after the orifice 29. This is obtained by using the switching valve 30 and introducing the fluid pressure obtained thereby into the fluid pressure chambers 34, 35 formed on the left and right of the cam ring 17.

Therefore, in such a pump, as compared with the case where the cam ring 17 is directly moved and displaced by the differential pressure before and after the orifice 29 provided in the middle of the pump discharge side passage,
A fluid pressure difference sufficient to move the cam ring 17 can be obtained by the switching valve 30, so that the required displacement of the cam ring 17 can be obtained and the pump discharge flow rate can be controlled in a required state.

For example, even if the pump discharge pressure becomes high and the bodies 11 and 12 are distorted or deformed, or dust or the like is mixed in the fluid to intervene in the position where the movement of the cam ring 17 is hindered, the cam ring 17 will be damaged. The force for moving 17 can be obtained by comparing the pump discharge pressure with a sufficiently small pump suction pressure, and the cam ring 17 can be moved and displaced lightly with a strong force. As a result, a predetermined flow rate can be stably obtained, and the differential pressure before and after the orifice may be small, and the power consumption can be saved.

In addition, with such a configuration, the variable displacement pump 10 capable of reducing energy loss and oil temperature rise as compared with the displacement pump is extremely simple and causes an increase in size of the pump itself. It can be obtained without any problems, is excellent in workability and assembly, and is excellent in mass productivity. Here, in this embodiment, the cam ring 17 is configured to be movable and displaceable in a state of being eccentric to the rotor 15, and the inner peripheral wall thereof can be formed in a perfect circular shape, which is excellent in workability. .

According to the present invention, in the variable displacement pump 10 having the above-described structure, according to the present invention, the pump chamber 18 is formed by being fitted on the outer periphery of the rotor 15 in the body 11 and depending on the flow rate on the pump discharge side. The first and second fluid pressure chambers 34, 35, through which the fluid pressure is introduced, are a side wall portion provided in contact with the side surface portion of the cam ring 17 formed on the outer peripheral side, the pressure plate 20, and the vane in the rear body 12. The suction side region 18A and the discharge side region 18 of the pump chamber 18, which are portions corresponding to the base ends of the storage slit grooves 15b.
The pump suction side and the pump discharge side arcuate groove portions 50 and 51, which are respectively formed corresponding to B and into which the fluid pressures of the pump suction side and the discharge side are introduced, are provided. The pump discharge side arcuate groove portion 51 is formed near the suction start end of the side region 18A,
It is characterized in that the starting end portion 51a is formed so as to reach the suction side region 18A of the pump chamber.

Here, according to the present embodiment, the vane 15a is
In forming the pump suction side and the pump discharge side arcuate groove portions 50, 51 provided in the pressure plate 20 for introducing pressure on the pump suction side and the discharge side at the base end of the Side arcuate groove portion 50,
As shown in FIG. 2, in the pump suction side region 18A, a region range of about 2/3 from the suction start end, for example, 60
It is formed up to the position of about%. Further, the pump discharge side arcuate groove portion 51 is arranged at an isolated angle so as not to communicate with the pump suction side arcuate groove portion 50 even when the rotor 15 is rotating, and the remaining one in the pump suction side region 18A. It is formed over the entire pump discharge side region 18B including a region range of about / 3, for example, an angle range of about 30 to 40%.

With this structure, the first and second fluid pressure chambers 34, 35 formed on both sides of the outer peripheral portion of the cam ring 17, which is eccentrically fitted to the rotor 15 in the body 11, are provided. , A fluid pressure having a predetermined pressure difference according to the flow rate on the pump discharge side is introduced to oscillate and displace the cam ring 17 in a predetermined direction, whereby the internal volume of the pump chamber 18 formed between the cam ring 17 and the rotor 15 Can be changed to variably control the fluid flow rate on the pump discharge side.

Here, in the present invention, in the vane 15a in the pump suction side region 18A, at the base end portion of the vane 15a near the discharge side, the above-mentioned starting end portion of the pump discharge side arcuate groove portion 51 is formed. Since a high pressure on the pump discharge side is exerted by 51a, even if the viscosity of the hydraulic oil is high at low temperature starting, the vane 15a can be ejected from the slit groove 15b to perform the suction and discharge operations of the pump 10. It is possible to improve the startability at low temperature.

Of course, the other pump suction side region 18
A, the vanes 15a in the discharge side region 18B are subjected to substantially the same pressure in accordance with the pressure inside the pump chamber 18 facing the respective tip portions, and the inner peripheral surface of the cam ring at the tip portions of the respective vanes 15a. It is possible to reduce the sliding resistance to 17a, eliminate the sliding friction and wear, and reduce the driving horsepower, and it is possible to eliminate the problems such as the conventional oil temperature rise.

1 to 3, reference numeral 52 denotes a passage for guiding the pump suction side fluid from the passage 25 to the pump suction side arcuate groove portion 50, and 53 denotes the pump discharge side pressure chamber 23 for the pump discharge side arcuate groove portion. The passage leading to 51, this passage 5
A part of 3 is formed as an orifice portion 53a by a small diameter passage. Such an orifice portion 53a is for ensuring the popping-out force of the vane 15a in a required state and smoothly obtaining the pump operation regardless of the fluid pressure fluctuation on the pump discharge side. In other words, the action of the orifice portion 53a makes it possible to obtain the pop-out property of the vane 15a in a required state without being affected by the fluid pressure fluctuation on the pump discharge side.

The present invention is not limited to the structure of the embodiment described above, and the shape, structure, etc. of each portion can be freely modified or changed, and various modifications can be considered. For example, in the above-described embodiment, the case where the annular gap space that holds the cam ring 17 so as to be movable and displaced is formed between the annular space and the adapter ring 19 is shown, but the present invention is not limited to this, and is provided in the pump body 11. The cam ring 17 may be configured so as to be movable and displaceable.

Further, the vane type variable displacement pump 10 having the above-mentioned structure is not limited to the structure of the above-mentioned embodiment, and of course, various devices other than the power steering device described in the above-mentioned embodiment, It goes without saying that it may be applied to a device.

[0060]

As described above, according to the variable displacement pump according to the present invention, the rotor with the vane rotatable in the pump body and the pump chamber fitted to the outer periphery of the rotor to form the pump chamber are provided. First and second fluid pressures are guided to the outer peripheral portion between the body and the body in accordance with the flow rate on the pump discharge side.
Of the fluid pressure chamber and capable of oscillating displacement in the pump body, and a portion of the side wall portion provided in contact with the side surface portion of the cam ring, the portion corresponding to the base end portion of the vane housing slit groove of the rotor. A pump suction side and a pump discharge side arcuate groove portion, which are formed respectively corresponding to the suction side region and the discharge side region of the pump chamber and into which the fluid pressures of the pump suction side and the discharge side are introduced, The side arcuate groove is formed near the suction start end of the pump suction side region, and the pump discharge side arcuate groove is formed so that its start end faces the suction side region of the pump chamber, so a simple structure However, various excellent effects listed below are exhibited.

That is, according to the present invention, in the vane in the pump suction side region, a high pressure on the pump discharge side is applied to the base end portion of the vane near the discharge side. Even if the viscosity of the oil is high, the vane can be appropriately and reliably ejected, and the suction and discharge operations of the pump can be performed, thereby improving the startability at low temperatures.

Moreover, according to the present invention, in the vanes in the pump suction side region and the discharge side region other than the above, the pressure in the pump chamber facing the respective tip portions, that is, the suction side pressure or the discharge side pressure, The combined pressure is almost the same, and the discharge side pressure does not act on the base ends of all the vanes over the entire pump suction side area, so the tip of the vane slides on the inner surface of the cam ring. Reduce resistance,
It eliminates sliding friction and wear, is well-balanced, and minimizes driving horsepower.

That is, according to the present invention, with the above-described structure, the driving horsepower of the pump can be minimized to reduce the oil temperature rise and the like, while improving the startability at low temperatures.

According to the variable displacement pump of the present invention, the pump discharge side arcuate groove formed so as to reach the suction side region of the pump chamber is connected to the pump discharge side through the orifice portion. Therefore, in addition to the above-described effects, the vane can be ejected in a required state without being affected by pressure fluctuations on the pump discharge side, and suction and discharge of the pump can be performed.

Further, according to the present invention, the arc-shaped groove portion on the pump suction side is formed over the range of about 2/3 from the suction start end in the pump suction-side region, and the arc groove portion on the pump discharge side is formed. By forming over the pump discharge side area including the remaining 1/3 range in the suction side area, the vane popping-out property at low temperature is improved, the low temperature startability is improved, and the pump operation in the normal state is performed. The sliding resistance in the inside can be reduced, and the action and effect in reducing the driving horsepower can be exhibited.

According to the present invention as described above, when it is used as a pump for a power steering apparatus of an automobile, for example, it is possible to solve the problem that the steering wheel is heavy when the engine is started in the severe winter season. Is.

[Brief description of drawings]

FIG. 1 is a schematic cross-sectional view showing an embodiment of a variable displacement pump according to the present invention and showing a main structure of the pump.

FIG. 2 is a schematic explanatory diagram for explaining a main part configuration of the present invention.

3 is a longitudinal cross-sectional view of a main part showing a cross-section of the main part structure of FIG.

FIG. 4 is a cross-sectional view of a main part of the switching valve portion of FIG.

FIG. 5 (a) shows a variable displacement pump of the present invention.
FIG. 3 is a characteristic diagram showing a discharge flow rate characteristic with respect to a pump rotation speed, FIG. 7B is a eccentric amount of a cam ring with respect to a pump rotation speed, and FIG.

[Explanation of symbols]

10 ... vane type variable displacement pump, 11 ... front body, 12 ... rear body, 13 ... pump components, 14 ... storage space, 15 ... rotor, 15a ...
... vanes, 15b ... slit grooves, 16 ... drive shaft (rotating shaft), 17 ... cam ring, 17a ... cam surface, 18 ... pump chamber, 18A ... pump suction side area, 18B ... pump discharge side Area, 19 Adapter ring, 20 Pressure plate, 21 Seal pin (cam ring shaft support), 23 Pump discharge side pressure chamber, 23a Pump discharge passage, 24 Pump discharge passage, 25 Pump suction side passage, 25b ... low pressure side passage, 26 ... suction port, 28 ... pump discharge side passage,
28b ... high pressure side passage, 29 ... metering orifice, 29a ... passage, 29b ... passage, 30 ... switching valve, 31 ... spring, 32 ... spool, 34 ... first fluid pressure chamber, 35 ... Second fluid pressure chamber, 36 ... Pressure guiding passage, 37 ... Pressure guiding passage, 40 ... Pressing member, 41 ...
Coil spring, 47 ... Second seal pin, 50 ... Pump suction side arcuate groove, 51 ... Pump discharge side arcuate groove, 51a ... Groove start, 52 ... Passage, 53 ... Passage, 53a. Orifice part.

Claims (3)

[Claims] 1. A rotor, which has a vane and is rotatably disposed in a pump body, and a rotor which is fitted around the rotor to form a pump chamber and which is located at an outer peripheral portion between the pump body and a pump discharge side. A cam ring which is formed with first and second fluid pressure chambers through which a fluid pressure corresponding to a flow rate is guided and which can be oscillated and displaced in a pump body, and the side wall portion arranged in contact with a side surface portion of the cam ring. A portion of the rotor corresponding to the base end of the slit groove for vane storage, which is formed corresponding to the suction side region and the discharge side region of the pump chamber, respectively, and the fluid pressure on the pump suction side and the discharge side is introduced. A pump suction side and a pump discharge side arcuate groove portion are provided, the pump suction side arcuate groove portion is formed near the suction start end of the pump suction side region, and the pump discharge side arcuate groove portion is formed. Variable displacement pump beginning of characterized by being formed so as to face up to the suction side region of the pump chamber. 2. The variable displacement pump according to claim 1, wherein the pump discharge side arcuate groove portion formed so as to reach the suction side region of the pump chamber is connected to the pump discharge side via the orifice portion. Variable displacement pump characterized by. 3. The variable displacement pump according to claim 1, wherein the pump suction side arcuate groove portion is formed in the pump suction side region over a range of about 2/3 from the suction start end, and The variable displacement pump, wherein the pump discharge side arcuate groove is formed over the pump discharge side region including the remaining 1/3 range in the pump suction side region.