JP3631264B2 - Variable displacement pump - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a variable displacement vane pump used in a pressure fluid utilizing device such as a power steering device that reduces the steering force of an automobile.
[0002]
[Prior art]
Conventionally, a displacement type vane pump that is directly driven to rotate by an automobile engine has been used as a power steering device pump. However, such displacement pumps increase or decrease the discharge flow rate in accordance with the engine speed, which is the driving source, so that a large steering assist force is generated when the vehicle is stopped or traveling at low speed, and the steering assist force is generated when traveling at high speed. This is a characteristic that is contrary to that of the power steering device.
[0003]
Therefore, such a pump is used that can secure a discharge flow rate at which a required steering assist force can be obtained even when traveling at a low speed with a low rotation speed, and a constant discharge flow rate when the rotation speed increases. A flow control valve for controlling the amount below the required amount is essential. For this reason, in such a pump, the number of components increases, the structure is complicated, the passage structure is also complicated, and the overall size and cost are inevitable.
[0004]
Further, when a flow rate control valve is used, part or most of the pump discharge flow rate is recirculated to the tank side, so that there is a problem that the driving horsepower increases, energy loss increases, and the oil temperature rises. .
[0005]
In order to solve such problems in the capacity type, variable capacity type vane pumps capable of decreasing the discharge flow rate stepwise as the rotational speed increases are disclosed in, for example, Japanese Patent Laid-Open Nos. 53-130505 and 56. Various proposals have been made, for example, in JP-A-143383, JP-A-58-93978, and JP-A-63-14078.
[0006]
Such a variable displacement pump does not require a flow control valve like the displacement pump, prevents unnecessary driving horsepower from increasing, is excellent in energy efficiency, and has no return flow to the tank side. Therefore, the problem of oil temperature rise can be reduced, and problems such as leakage inside the pump and reduction in volumetric efficiency can be prevented.
[0007]
As such a variable displacement pump, for example, in Japanese Patent Application Laid-Open No. 56-143383, a cam ring is configured to be movable in a pump casing, and a pair of members are formed in a gap formed between the cam ring and the pump casing. Fluid pressure chambers that form control chambers are formed, the pressures before and after the orifices provided in the discharge passages are guided to the respective chambers, the differential pressure is applied directly to the cam ring, and the cam ring is appropriately resisted against the biasing force of the spring. An arrangement is disclosed in which the displacement of the pump chamber is changed by moving it so as to perform an appropriate discharge flow rate control.
[0008]
However, in such a pump, the cam ring is held so as to be linearly movable in the pump housing, and this is simply moved and displaced by the pressure difference on the downstream side on the orifice provided directly or indirectly in the discharge passage. There are many components and fluid passages in each part of the pump, and there are problems in terms of workability and assembly, as well as reliability in operation and durability, and poor feasibility.
[0009]
In order to solve such a conventional problem, the present applicant has previously proposed Japanese Patent Application No. 4-358801.
Briefly explaining this, the variable displacement vane pump is fitted in an eccentric state so as to form a pump chamber with the outer periphery of the rotor, and is disposed so as to be movable and displaceable within the pump body. The cam ring is urged to maximize the capacity. In addition, the first and second fluid pressure chambers for moving and displacing the cam ring in the pump body are formed by interposing a sealing means at a predetermined position in the annular gap space between the cam ring and the pump body. In addition, there is provided a switching valve that controls the supply fluid pressure 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.
[0010]
Further, in such a variable displacement pump, the outer periphery of the rotor within the cam ring is formed on the side wall portion disposed in contact with the side surface portion of the rotor and the cam ring and on the portion corresponding to the base end portion of the slit groove for storing the vane of the rotor. Arc-shaped groove portions corresponding to the pump suction side and pump discharge side in the pump chamber formed in each section are formed, and fluid pressures on the pump suction side and pump discharge side respectively corresponding to these arc-shaped groove portions are introduced. I try to let them.
[0011]
And according to such a structure, it act | operates according to the flow volume by the side of a pump discharge to the 1st, 2nd fluid pressure chamber formed in the both sides of the cam ring outer peripheral part eccentric with respect to a rotor within a pump body. By introducing a fluid pressure having a predetermined pressure difference from the switching valve into each chamber, the cam ring is oscillated and displaced in a predetermined direction. As a result, the pump chamber volume formed between the rotor and the rotor changes, The fluid flow rate on the pump discharge side is variably controlled.
[0012]
Further, in a vane that is held freely in and out of a rotor that rotates in the cam ring, when the tip of the vane slides along the inner peripheral surface of the cam ring, the vane tip is a pump discharge side region of the pump chamber. The tip of each vane is applied to the base end portion of each of the pump suction side regions by applying substantially the same pressure to the pressure in the pump chamber facing each vane tip portion. The sliding resistance to the cam ring inner peripheral surface is reduced, sliding friction and wear are eliminated, and compared with the case where high pressure pump discharge side pressure is applied to all the vane base end parts that were conventionally common It becomes possible to reduce driving horsepower.
[0013]
[Problems to be solved by the invention]
According to the variable displacement pump having the structure as described above, the pump suction side pressure, which is a low pressure, corresponds to the pump discharge side region at the base end portion of the vane that passes through the portion corresponding to the pump suction side region of the pump chamber. Since the high-pressure pump discharge side pressure is applied to the vane at the portion to be applied, the sliding resistance of the vane tip to the inner peripheral surface of the cam ring can be reduced, and the driving horsepower can be kept low.
[0014]
However, on the other hand, the pump having such a structure is difficult to start at a low temperature.
That is, since the viscosity of the hydraulic oil is high at low temperatures, the vane does not pop out only by the centrifugal force accompanying the rotation of the rotor, and the pressure on the pump discharge side does not increase. And in the rotor vane that corresponds to the pump suction side, the pump suction side pressure continues to act, so the vane does not jump out easily, and the vane popping out property, that is, the low temperature startability is poor, and as a result, the pump discharge side Pressure cannot be obtained, which causes a problem in terms of startability when the engine is cold.
[0015]
Such a problem, for example, when used in a pump for a power steering apparatus of an automobile, leads to a problem that the steering wheel is heavy in the severe winter season, and it is hoped that some measures that can solve such a problem are taken. It is rare.
[0016]
The present invention has been made in view of such circumstances, and a variable displacement pump capable of improving the startability at low temperatures while minimizing the drive horsepower of the pump and reducing the rise in oil temperature and the like. The purpose is to obtain.
[0017]
[Means for Solving the Problems]
In order to meet such a demand, the variable displacement pump according to the present invention includes a rotor having a vane rotatably disposed in a pump body, and a pump chamber that is fitted on the outer periphery of the rotor to form a pump chamber. First and second fluid pressure chambers in which fluid pressure is guided in accordance with the flow rate on the discharge side of the pump at the outer peripheral portion between the body and the cam ring that can be swung and displaced in the pump body, and side surfaces of the cam ring Is a portion corresponding to the base end of the slit groove for storing the vane of the rotor in the side wall portion disposed in contact with the portion, and is formed corresponding to the suction side region and the discharge side region of the pump chamber, respectively, and the pump suction side The arc-shaped groove on the pump suction side and pump discharge side where the fluid pressure on the discharge side is introduced Equipped with an arc-shaped groove on the pump discharge side, The starting end portion is formed so as to face the suction side region of the pump chamber.
[0018]
In the variable displacement pump according to the present invention, a pump discharge-side arcuate groove formed so as to face the suction side region of the pump chamber is connected to the pump discharge side through an orifice.
[0019]
Furthermore, the variable capacitance type according to the present invention The pump has an arc-shaped groove on the pump discharge side, Pump suction side area End side of It is formed over the pump discharge side region including the range of about 1/3.
[0020]
[Action]
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 that is eccentrically fitted to the rotor in the pump body have a predetermined pressure according to the flow rate on the pump discharge side. It is possible to introduce a fluid pressure with a difference and swing and displace the cam ring in a predetermined direction, thereby changing the pump chamber volume formed between the rotor and the rotor, and variably controlling the fluid flow rate on the pump discharge side It becomes.
[0021]
In particular, according to the present invention, in the vane in the pump suction side region, since the high pump discharge side pressure is applied to the vane base end near the discharge side, the viscosity of the hydraulic oil at the low temperature start Even if it is high, it is possible to eject the vane and perform the suction and discharge operations of the pump, and the startability at a low temperature 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 in the pump chamber facing the respective tip portions, and the cam ring at the tip portion of each vane It is possible to reduce sliding resistance to the inner peripheral surface, eliminate sliding friction and wear, and reduce driving horsepower.
[0022]
【Example】
1 to 4 show one embodiment of a variable displacement pump according to the present invention. In these drawings, in this embodiment, the case is a vane type oil pump serving as a hydraulic pressure generation source of a power steering apparatus. explain.
[0023]
First, a vane type variable displacement pump, generally indicated by reference numeral 10, includes a front body 11 and a rear body 12 constituting a pump body, as is apparent from FIGS. The front body 11 has a substantially cup shape as a whole, and a storage space 14 for storing and arranging the pump component 13 is formed therein, and the rear body 12 is assembled so as to close the open end of the storage space 14. Combined and integrated. The front body 11 has bearings 16a, 16b, 16c (16b on the rear body 12 side) in a state in which a drive shaft 16 for rotating the rotor 15 which is a rotor of the pump component 13 from the outside passes through. 16c are rotatably supported by a pressure plate 20 (to be described later).
[0024]
Reference numeral 17 denotes a cam ring having an inner cam surface 17a that is fitted and arranged on the outer peripheral portion of the rotor 15 having the vane 15a. The cam ring 17 forms a pump chamber 18 between the inner cam surface 17a and the rotor 15. As will be described later, the pump chamber 18 is disposed so as to be movable and displaceable in an adapter ring 19 provided in a fitted state on the inner wall of the storage space 14 so as to vary the volume of the pump chamber 18.
The adapter ring 19 is for holding the cam ring 17 in the housing space 14 of the body 11 so as to be movable and displaceable.
[0025]
Reference numeral 20 denotes a pressure plate which is arranged in pressure contact with the front body 11 side of the pump cartridge, which is constituted by the rotor 15, the cam ring 17 and the adapter ring 19, and the rear side of the rear body 12 is disposed on the opposite side of the pump cartridge. The end surfaces are pressed as side plates, and a required assembly state is obtained by integrally assembling the bodies 11 and 12. The pump component 13 is constituted by these members.
[0026]
Here, the pressure plate 20 and the rear body 12 serving as a side plate laminated on the pressure plate 20 via a cam ring 17 are provided by a seal pin 21 (to be described later) that also functions as a positioning pin or an appropriate detent means (not shown). These are assembled and fixed integrally in a state of being positioned in the rotation direction.
[0027]
Reference numeral 23 denotes a pump discharge side pressure chamber formed on the bottom side in the storage space 14 of the front body 11 so that the pump discharge side pressure is applied to the pressure plate 20. Reference numeral 24 denotes a pump discharge side passage formed in the pressure plate 20 for guiding the pressure oil from the pump chamber 18 to the pump discharge side pressure chamber 23.
[0028]
25 is a pump suction side passage 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; The passage 25 is connected to the pump chamber 18 through a pump suction opening 25 a that opens to the end face of the rear body 12.
[0029]
28 is a pump discharge side passage connected from the pump chamber 18 to the pump discharge side passage 24, a pump discharge side pressure chamber 23, and a passage hole 23a extending from the pressure chamber 23 to the upper side of the front body 11. A metering orifice 29 is provided in the middle of the passage 28, and a discharge port for supplying pump discharge side fluid pressure to a hydraulic device such as a power steering device (indicated by PS in the figure) (not shown) on the outer end side. Is provided.
[0030]
A switching valve 30 is disposed substantially orthogonally above the storage space 14 in the front body 11 and is used to move and displace the cam ring 17 with respect to the rotor 15 in the pump body 11 (adapter ring 19). Reference numeral 30 denotes a spool 32 with a relief valve that slides in the valve hole 30 a formed in the body 11 by the pressure difference before and after the metering orifice 29 of the pump discharge side passage 28 and the biasing force of the spring 31. It has.
[0031]
In FIG. 4, 29a and 29b are passages for introducing the pressure 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 side passage 25b is formed to open, and is selectively controlled to open and close as the spool 32 moves, so that fluid pressure is introduced into first and second fluid pressure chambers to be described later.
[0032]
That is, in such a switching valve 30, one chamber (the left chamber in FIGS. 1 and 4) 32a of the spool 32 is connected to the pump discharge side pressure chamber 23, the pump discharge side passage 28, and the passage 29a. The fluid pressure upstream of the metering orifice 29 is introduced. In the figure, reference numeral 33 denotes a plug for closing the valve hole 30a having a rod 33a for locking the position of the spool 32 to the left in the valve hole 30a at a position not closing the opening end of the passage 29a.
[0033]
A spring 31 is disposed in the other chamber 32b (the right chamber in FIGS. 1 and 4) of the spool 32, and the fluid pressure downstream of the metering orifice 29 from the middle of the passage 28 leading to the discharge port 28a. It is guided through the passage 29b.
[0034]
Further, the first and second fluids formed between the outer peripheral portion of the cam ring 19 and the adapter ring 19 on the body 11 side at a position aligned in the moving direction of the spool 32 at a substantially central portion of the valve hole 30a. In the pressure chambers 34 and 35, pressure guiding passages 36 and 37 (including passage holes 36a and 37a of the adapter ring 19) formed through the body 11 and the adapter ring 19 are formed. In FIG. 1, reference numeral 34 a denotes a concave 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.
[0035]
These passages 36 and 37 are moved to the pump discharge side passage 28 via the passage 29b or 28b or to the pump suction opening 25b side, as is apparent from FIGS. It is selectively connected via the passage 25b.
[0036]
On the other hand, reference numeral 40 in FIG. 1 denotes a pressing member that urges the cam ring 17 disposed so as to be movable and displaceable without the pump bodies 11 and 12 so that the pump chamber 18 formed at the outer peripheral portion of the rotor 15 has a maximum volume. Thus, the coil spring 41 and the cylindrical presser plug 42 are used.
[0037]
In the vane type variable displacement pump 10 described above, configurations other than those described above are well known in the art and will not be described in detail.
[0038]
In the variable displacement pump 10 having the above-described configuration, it is fitted in an eccentric state so as to form a pump chamber 18 between the outer periphery of the rotor 15 and is arranged to be movable and displaceable in the pump bodies 11 and 12. On the outer periphery of the cam ring 17 that is urged so that the volume of the pump chamber 18 is maximized, seal pins 21 and 47 as seal means are provided at predetermined locations in the annular gap space between the pump bodies 11 and 12. By interposing, the first and second fluid pressure chambers 34 and 35 for swinging and displacing the cam ring 17 in the pump bodies 11 and 12 are formed, and according to the discharge flow rate of the pressure oil from the pump chamber 18. A switching valve 30 is provided that is operated to control the fluid pressure supplied to the first and second fluid pressure chambers 34 and 35.
[0039]
Here, in order to divide the annular gap space between the cam ring 17 and the adapter ring 19, the annular gap space is divided into left and right as is apparent from FIGS. In addition, a first seal pin 21 positioned above and below and functioning also as a positioning pin is provided, and a second seal pin 47 incorporated through an elastic member in a groove formed in the sliding contact surface of the cam ring 17 is provided. Yes.
[0040]
The left space is a first fluid pressure chamber 34, and the chamber 34 is configured to be connectable to the left chamber 32a of the switching valve 30 or the pump suction side via the fluid passages 36a and 36.
The right space is a second fluid pressure chamber 35, and this chamber 35 is connected to the pump discharge side or pump suction side in accordance with the movement of the spool 32 in the central portion of the switching valve 30 via the fluid passages 37 a and 37. It is configured to be selectively connectable to.
[0041]
Further, as is apparent from FIG. 1, the pressing member 40 having a cylindrical shape described above is configured to always press the cam ring 17 leftward in FIG. 1 by a coil spring 41. The pressing member 40 may have any shape as long as it can press the cam ring 17 and always press the cam ring 17 so that the internal volume of the pump chamber 18 is maximized.
[0042]
According to the above configuration, when the pump 10 is started, the cam ring 17 has a maximum internal volume of the pump chamber 18 between the rotor 15 and one side of the housing space 14 of the body 11 as is apparent from FIG. Thus, it is in a state of being biased by the coil spring 41 of the pressing member 40. 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. It is in.
[0043]
When the pump rotational speed is gradually increased and driven, the spool 32 of the switching valve 30 is obtained by the differential pressure due to the fluid pressure on the orifice 29 on the downstream side of the pump, which is obtained in proportion to the pump rotational speed. Thus, 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. The eccentric cam ring 17 is moved and displaced in the direction in which the internal volume of the pump chamber 18 decreases against the coil spring 41 (see FIG. 1).
[0044]
At this time, the pump discharge side is positioned opposite to the first fluid pressure chamber 34 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 suction side is appropriately connected to the fluid pressure chamber 35, so that the cam ring 17 is appropriately moved and displaced depending on the operating state of the switching valve 30. It can be performed in a required state, and can be fed at a predetermined flow rate that reaches the power steering device PS.
[0045]
In particular, according to the above-described configuration, the switching valve 30 is switched and controlled by the differential pressure generated at the metering orifice 29 according to the pump discharge amount that increases and decreases with the pump rotation speed, whereby the cam ring 17 is attached to the coil spring 41. As a result, the internal volume of the pump chamber 18 can be variably controlled, and the discharge amount from the pump can be set as shown in FIG. It can be balanced according to the number of rotations of the pump and controlled so as to obtain desired characteristics.
[0046]
In addition, the characteristic curve shown to (a) of FIG. 5 has shown the characteristic of the pump discharge flow volume with respect to pump rotation speed. Further, (b) in the figure shows an eccentric state of the cam ring 17 with respect to the pump rotation speed, and (c) in the same figure shows a pump specific discharge amount (of the rotor 15 with respect to the eccentric state of the cam ring 17). Discharge amount per rotation).
[0047]
According to the above-described configuration, the first and second fluid pressure chambers 34 and 35 formed on both sides of the outer peripheral portion of the cam ring 17 that is eccentrically fitted to the rotor 15 in the pump bodies 11 and 12, Fluid pressure having a predetermined pressure difference can be introduced into each of the chambers 34 and 35 by the switching valve 30 that is operated according to the flow rate on the pump discharge side, so that the cam ring 17 can move 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 required state.
[0048]
In particular, in the present embodiment, the switching valve 30 for controlling the cam ring that is operated by switching the displacement of the cam ring 17 that swings around the seal pin 21 around the seal pin 21 by the differential pressure before and after the orifice 29 in the present embodiment. And the fluid pressure obtained thereby is introduced into fluid pressure chambers 34 and 35 formed on the left and right sides of the cam ring 17.
[0049]
Therefore, in such a pump, 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, there is sufficient fluid to move the cam ring 17 by the switching valve 30. The pressure difference can be obtained, and the required displacement of the cam ring 17 can be obtained to control the pump discharge flow rate in a required state.
[0050]
For example, even if the pump discharge pressure becomes high and the bodies 11 and 12 are distorted and deformed, or even if dust or the like is mixed in the fluid and intervenes at a position where the movement of the cam ring 17 is prevented, the cam ring 17 is moved. The force to be generated 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 easily with a strong force. As a result, a predetermined flow rate can be stably obtained, the differential pressure before and after the orifice can be small, and power consumption can be saved.
[0051]
Further, with such a configuration, it is possible to obtain the variable displacement pump 10 that can reduce the energy loss and the oil temperature rise as compared with the displacement pump very easily and without increasing the size of the pump itself. It is possible, and is excellent in workability and assemblability, and in mass production. Here, in this embodiment, the cam ring 17 is configured to be movable and displaceable with the rotor 15 being eccentric, and the inner peripheral wall thereof can be formed in a perfect circle shape, which is excellent in terms of workability. .
[0052]
In the variable displacement pump 10 configured as described above, according to the present invention, the pump chamber 18 is formed by being fitted to the outer periphery of the rotor 15 in the body 11, and the flow rate on the pump discharge side is adjusted. Depending on Pressure plate 20 which is a side wall portion disposed in contact with the side surface portion of cam ring 17 in which first and second fluid pressure chambers 34 and 35 to which fluid pressure is guided are formed on the outer peripheral side, and vanes in rear body 12 The portion corresponding to the base end portion of the housing slit groove 15b is formed corresponding to each of the suction side region 18A and the discharge side region 18B of the pump chamber 18, and the fluid pressure on the pump suction side and the discharge side is introduced. The pump suction side and pump discharge side arcuate grooves 50, 51 are provided, the pump suction side arcuate groove 50 is formed near the suction start end of the pump suction side region 18A, and the pump discharge side arcuate groove 51 is formed. It is characterized in that the start end 51a is formed so as to face the suction side region 18A of the pump chamber.
[0053]
Here, according to the present embodiment, the pump suction side and the pump discharge side arcuate groove 50 provided on the pressure plate 20 or the like to introduce pressure on the pump suction side and discharge side to the base end portion of the vane 15a, In forming the arcs 51 separately from each other, the arcuate groove 50 on the pump suction side is, as shown in FIG. 2, a region range of about 2/3 from the suction start end in the pump suction side region 18A, for example, 60%. Form up to a certain position. The pump discharge-side arcuate groove 51 is disposed at an angle separated from the pump suction-side arcuate groove 50 so as not to communicate with the pump suction-side arcuate groove 50 even when the rotor 15 is rotating. End side of It is formed over the entire pump discharge side region 18B including an area range of about 1/3, for example, an angle range of about 30 to 40%.
[0054]
According to such a configuration, the first and second fluid pressure chambers 34 and 35 formed on both sides of the outer periphery of the cam ring 17 that is eccentrically fitted to the rotor 15 in the body 11 are discharged to the pump. A fluid pressure having a predetermined pressure difference is introduced according to the flow rate on the side, and the cam ring 17 is oscillated and displaced in a predetermined direction, thereby changing the internal volume of the pump chamber 18 formed between the rotor 15 and the cam ring 17. The fluid flow rate on the pump discharge side can be variably controlled.
[0055]
Here, in the present invention, in the vane 15a in the pump suction side region 18A, the base end portion of the vane 15a near the discharge side has a high pressure by the start end portion 51a of the pump discharge side arc-shaped groove portion 51 described above. Since the pump discharge side pressure is applied, it is possible to cause the vane 15a to jump out of the slit groove 15b and perform the suction and discharge operations of the pump 10 even when the viscosity of the hydraulic oil is high at low temperature start. The startability at low temperatures can be improved.
[0056]
Of course, in the other vanes 15a in the pump suction side region 18A and the discharge side region 18B, substantially the same pressure is applied in accordance with the pressure in the pump chamber 18 facing the respective tip portions. It is possible to reduce sliding resistance to the cam ring inner peripheral surface 17a at the tip of 15a, eliminate sliding friction and wear, reduce driving horsepower, and eliminate conventional problems such as oil temperature rise. be able to.
[0057]
1 to FIG. 52 in FIG. Is a passage that leads the pump suction side fluid from the passage 25 to the arcuate groove 50 on the pump suction side, 53 is a passage that leads the pump discharge side pressure chamber 23 to the arcuate groove 51 on the pump discharge side, and a part of this passage 53 is An orifice 53a is formed by a small diameter passage.
Such an orifice portion 53a is provided for ensuring the pop-out force of the vane 15a in a required state regardless of the fluid pressure fluctuation on the pump discharge side, and smoothly obtaining the pump operation. In other words, the effect of the orifice 53a is not affected by the fluid pressure fluctuation on the pump discharge side, and the pop-out property of the vane 15a can be obtained in a required state.
[0058]
Note that the present invention is not limited to the structure of the above-described embodiment, and the shape and structure of each part can be freely modified and changed, and various modifications can be considered.
For example, in the above-described embodiment, the case where the annular gap space for holding the cam ring 17 so as to be movable and displaceable is formed between the adapter ring 19, but the present invention is not limited to this, and the pump body 11 is not limited to this. You may comprise so that the cam ring 17 may be hold | maintained so that movement displacement is possible.
[0059]
Furthermore, the vane-type variable displacement pump 10 having the above-described configuration is not limited to the structure of the above-described embodiment, but is applicable to various devices and apparatuses other than the power steering apparatus described in the above-described embodiment. Needless to say, you can.
[0060]
【The invention's effect】
As described above, according to the variable displacement pump according to the present invention, a rotor with a vane that is rotatable in the pump body and a pump chamber that is fitted on the outer periphery of the rotor are formed between the pump body and the rotor. The flow rate on the pump discharge side Depending on A cam ring having first and second fluid pressure chambers through which fluid pressure is guided and capable of swinging and displacement in the pump body, and a rotor vane storage in a side wall portion disposed in contact with a side surface portion of the cam ring Pump suction side and pump discharge corresponding to the base end of the slit groove and 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. Side arc-shaped groove Equipped with pump Since the discharge-side arc-shaped groove is formed so that its start end faces the suction-side region of the pump chamber, the following excellent effects can be obtained despite the simple structure.
[0061]
That is, according to the present invention, in the vane in the pump suction side region, since the high pump discharge side pressure is applied to the vane base end portion near the discharge side, the viscosity of the hydraulic oil at low temperature start-up Even if it is high, the vane can be ejected appropriately and reliably, and the suction and discharge operations of the pump can be performed, thereby improving the startability at a low temperature.
[0062]
Moreover, according to the present invention, in the vanes in the pump suction side region and the discharge side region other than those described above, the pressure in the pump chamber facing the respective tip portions, that is, the suction side pressure or the discharge side pressure is substantially matched. Since the same pressure is applied and the discharge side pressure does not act on the base end of all the vanes over the entire area on the pump suction side, the sliding resistance of the vane tip to the cam ring inner peripheral surface is reduced. In addition, sliding friction and wear are eliminated, the balance is good, and the driving horsepower can be minimized.
[0063]
That is, according to the present invention, with the above-described configuration, the drive horsepower of the pump can be reduced to the minimum necessary, the oil temperature rise can be reduced, and the startability at a low temperature can be improved.
[0064]
Further, according to the variable displacement pump of the present invention, the pump discharge side arc-shaped groove formed so as to face the suction side region of the pump chamber is connected to the pump discharge side through the orifice. In addition to the above-described operational effects, the vane can be popped out in a required state without being affected by the pressure fluctuation on the pump discharge side, and the suction and discharge of the pump can be performed.
[0065]
further, According to the present invention, the pump discharge-side arcuate groove is , Pump suction side area End side of By forming over the pump discharge side region including the range of about 1/3, the vane pop-out property at low temperature is improved, the low temperature startability is improved, and the sliding resistance during pump operation in the normal state is improved. It is possible to reduce the driving force and reduce the driving horsepower.
[0066]
According to the present invention as described above, for example, when used as a pump for a power steering apparatus of an automobile, problems such as a heavy handle that has occurred at the start of the engine in a severe winter season can be solved.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a main structure of a pump according to an embodiment of a variable displacement pump according to the present invention.
FIG. 2 is a schematic explanatory diagram for explaining a main configuration of the present invention.
3 is a vertical cross-sectional view of a main part showing a cross-sectional view of the main part structure of FIG. 1;
4 is a cross-sectional view of a main part of the switching valve portion of FIG.
5 (a) shows the discharge flow rate characteristic with respect to the pump speed, (b) shows the eccentric amount of the cam ring with respect to the pump speed, and (c) shows the eccentric quantity in the variable displacement pump of the present invention. It is a characteristic view which shows a specific discharge amount.
[Explanation of symbols]
10 ... Vane type variable displacement pump, 11 ... Front body, 12 ... Rear body, 13 ... Pump components, 14 ... Storage space, 15 ... Rotor, 15a ... Vane, 15b ... Slit groove , 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 side passage, 24 ... Pump discharge side 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, 2 9b ... passage, 30 ... switching valve, 31 ... spring, 32 ... spool, 34 ... first fluid pressure chamber, 35 ... second fluid pressure chamber, 36 ... pressure guide passage, 37 ... ··· Pressure guiding passage, 40 ··· Pressing member, ···· 41 ··· Coil spring, ····························································································· , 52... Passage, 53... Passage, 53 a.

Claims (3)

A rotor having a vane and rotatably disposed in the pump body;
The first and second fluid pressure chambers are formed in the outer periphery between the rotor body and the pump body, and the fluid pressure is guided to the outer periphery between the rotor body and the pump body according to the flow rate on the pump discharge side. A cam ring that can swing and displace within the body,
A portion corresponding to the base end portion of the slit groove for storing the vane of the rotor in the side wall portion disposed in contact with the side surface portion of the cam ring, corresponding to the suction side region and the discharge side region of the pump chamber, respectively. The pump suction side, the pump suction side into which the fluid pressure on the pump suction side and the discharge side is introduced, and the pump discharge side are provided with arcuate grooves ,
A variable displacement pump characterized in that the pump discharge-side arc-shaped groove is formed so that its starting end faces the suction side region of the pump chamber. The variable displacement pump according to claim 1, wherein
A variable displacement pump characterized in that a pump discharge side arc-shaped groove formed so as to face the suction side region of the pump chamber is connected to the pump discharge side through an orifice. The variable displacement pump according to claim 1 or 2,
The pump discharge side arc-shaped groove is formed over a pump discharge side region including a range of about 1/3 of a terminal end side of the pump suction side region.

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