JPH04272488A - Rotary pump - Google Patents

Abstract

PURPOSE:To prevent the cabitation in a suction path in good performance without bringing about increase of the mass. CONSTITUTION:A supercharge path 9 couples the feedback discharge hole 76 of a feedback control valve directly with the suction port, in such an arrangement that the direction of working fluid does not change steeply at the junction of the supercharge path 9 with the suction port 5. The supercharge path 9 functions as a diffuser, and the pressure of the working fluid inflowing from the discharge hole 76 to the supercharge path 9 will rise gradually in the supercharge path 9. According to the invention, in which the supercharge path 9 and the suction port 5 are directly coupled without steep change of the stream line, the velocity energy of the working fluid having flowed into the suction port 5 from the supercharge path 9 is still more collected as pressure energy even in the suction port 5.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a rotary pump (hereinafter also simply referred to as pump) having an oil return function and equipped with a return control valve for returning a part of working fluid from a discharge port to a suction port. ) regarding.

0002

[Prior Art] Conventionally, a part of working fluid discharged from a discharge port is passed through a reflux control valve that controls the amount of reflux.
Furthermore, vane pumps (for example, power steering pumps) are known in which the working fluid is returned to the suction port through the suction passage and the annular suction chamber, and similarly, a portion of the working fluid discharged from the discharge port is returned to the recirculation amount. An internal gear pump is known in which the flow is returned to the suction port via a return control valve that controls the flow and further through a supercharging path. Here, the suction passage and the supercharging passage are generally formed to be relatively long in order to recover the velocity energy of the recirculating working fluid as pressure energy.

Furthermore, in the vane pump described above, the suction passage is generally connected to the annular suction chamber in the normal direction, whereas in the internal gear pump, the flow line of the supercharging passage is connected to the suction port. Generally, the two are connected perpendicularly to the flow line direction of the part. As a result, there is a problem in that eddy currents and bubbles are generated and cavitation occurs at the junction between the suction passage of the vane pump and the suction chamber, and at the junction between the supercharging passage and the suction port of the internal gear pump. There is.

[0004] In order to improve this problem, Japanese Patent Laid-Open No. 2-2
Publication No. 6715 discloses that, in the above vane pump, the working fluid flows into the suction chamber from the suction passage in the tangential direction of the working fluid flowing through the annular suction chamber, and the cross-sectional area of the annular suction chamber is reduced near the suction passage. It is disclosed that the air pressure gradually decreases from the point near the suction port. The above-mentioned Japanese Patent Application Publication No. 2-267
The vane pump disclosed in Publication No. 15 allows the working fluid in the suction passage and the working fluid in the annular suction chamber to merge in substantially the same direction, thereby suppressing the generation of vortices and bubbles, thereby suppressing the occurrence of cavitation. can do.

[0005]

However, in recent years, there has been a demand for rotary pumps to rotate at higher speeds and to be more compact, and efforts have been made to further increase the speed of the working fluid inside the pumps. However, the most important problem when trying to make rotary pumps smaller and rotate at higher speeds is that the suction of working fluid cannot follow the high speed rotation of the rotor due to increased fluid resistance in the suction path. In the vane pump of the above-mentioned publication, the working fluid flowing from the suction passage into the annular suction chamber is throttled by the fluid resistance of the annular suction chamber. The pressure in the suction chamber decreases from the suction passage to the suction port,
Cavitation may occur.

Furthermore, if the suction passage and supercharging passage of the conventional rotary pump described above are extended, the velocity energy of the working fluid passing through these parts can be recovered as pressure energy, and at least the cavities in these suction passages and supercharging passage can be recovered. - It is possible to prevent pumping and improve pump efficiency. However, such extension of the suction passage and supercharging passage requires an increase in the size of the pump, and in the vane pump described above, even if pressure is recovered in the suction passage, pressure is lost in the next annular suction chamber and the cavity collapses. - There is still a possibility that tion may occur.

The present invention has been made in view of these problems with rotary pumps, and an object of the present invention is to provide a rotary pump that can effectively prevent cavitation from occurring in the suction path.

[0008]

[Means for Solving the Problems] The rotary pump of the present invention includes:
A casing having a cylindrical working chamber formed therein, a rotor rotatably supported within the working chamber, and a plurality of working spaces protruding from the rotor in a substantially centrifugal direction within the working chamber. a plurality of protrusions that define a plurality of projections that continuously change the volume of each of the working spaces by rotation; and a plurality of protrusions that are recessed at predetermined positions on the inner end surface of the casing that define side end surfaces of the working chambers. - a suction port and a discharge port arranged in an arc shape around the axis of the motor, and a portion of the working fluid discharged from the discharge port that flows back to the suction port; a reflux control valve to be controlled, and a supercharging passage that communicates a reflux discharge port of the reflux control valve with the suction port and supplies working fluid to the suction port, The supercharging passage and the suction port are formed so that the flow line direction substantially coincides with the tangential direction of the arc-shaped suction port, so that the supercharging passage and the suction port are smoothly continuous.

[0009] Here, "approximately coincident" means that at the junction point of the supercharging passage and the suction port, which is the farthest point from the reflux control valve, the direction of extension of the supercharging passage and the suction port are the same. This indicates that the angle between the tangential direction and the tangential direction is 20 degrees or less. In one preferred embodiment, the supercharging path has a straight pipe shape extending obliquely to the longitudinal direction of the reflux control valve. In this way, the recirculation control valve can be placed close to the suction port without sacrificing the length of the supercharging path, and it is easy to manufacture.

In another preferred embodiment, the cross-sectional area of the suction port in the direction perpendicular to the streamline is greater than or equal to the cross-sectional area of the supercharger passage in the direction perpendicular to the streamline in the vicinity of the junction with the supercharger passage. is formed. In this way, the working fluid flowing into the suction port from the supercharging path is not throttled by the suction port.

[0011]

[Operation] In the rotary pump of the present invention, the rotor and the
When the plurality of protrusions protruding approximately centrifugally on the motor rotate, the volume of each working space defined by the plurality of protrusions changes continuously with the rotation, thereby sucking working fluid from the suction port. and discharge it to the discharge port. The reflux control valve controls the flow rate of working fluid reflux from the discharge port to the suction port.

[0012] The supercharging passage directly connects the reflux discharge port of the reflux control valve to the suction port, and is designed to prevent sudden changes in the direction of the working fluid at the junction between the supercharging passage and the suction port. I'm trying to do that. Here, the supercharging passage functions as a diffuser, and the pressure of the working fluid flowing into the supercharging passage from the discharge port gradually increases within the supercharging passage. In particular, in the present invention, the supercharging path and the suction port are directly connected without sudden changes in the flow line, and the suction port itself functions as a part of the supercharging path, resulting in an extension of the supercharging path. The velocity energy of the working fluid flowing into the suction port from the supercharging path is further recovered as pressure energy within the suction port.

[0013]

As explained above, in the rotary pump of the present invention, the supercharging passage directly connects the discharge port of the reflux control valve and the suction port, and the flow line direction near the outlet of the supercharging passage is Since it is aligned approximately with the tangential direction of the suction port,
The port can have a pressure recovery function as a part of the supercharging path, eliminating low-pressure parts throughout the suction path (i.e., the supercharging path and suction port), suppressing the occurrence of cavitation, and Pump efficiency can be improved by recovering velocity energy. Furthermore, since the above effects can be achieved without extending the supercharging path, an excellent effect can be achieved without causing an increase in the size of the pump.

(Embodiment 1) An embodiment of the present invention will be described with reference to a trochoid pump shown in FIGS. 1 and 2. This trochoid pump is a hydraulic pump for driving a hydraulic fan for cooling a radiator of an automobile. The drive shaft 2 passes through, the inner rotor (rotor in the present invention) 3 is fixed to the drive shaft 2 in the working chamber 10, and the inner rotor 3 meshes with the inner rotor 3.
an outer rotor (rotor in the present invention) 4 forming a plurality of working spaces S therebetween, and each working space S formed in the casing 1 as the inner rotor 3 and outer rotor 4 rotate. It has a suction port 5 and a discharge port 6 which communicate with each other in sequence.

As shown in FIG. 2, the casing 1 includes a central cylindrical portion 11 having a short-axis cylindrical working chamber 10 with openings at both ends in the center, and an operating chamber sandwiching the central cylindrical portion 11 in the axial direction. Room 1
It consists of a front wall part 12 and a rear wall part 13 that close the 0, and these three parts are fastened together by four bolts 19. A shaft hole 14 with openings at both ends is provided through the front wall portion 12 , and the rear wall portion 1
3 has a shaft hole 15 opened to the working chamber 10 side, and the drive shaft 2 is fitted into these shaft holes 14 and 15.

The drive shaft 2 is rotatably supported by a bearing 21 in the shaft hole 14 and a bearing 22 in the shaft hole 15, and is driven by a vehicle engine (not shown) through a pulley 23. Further, an oil seal 16 is fitted in the shaft hole 14 of the drive shaft 2 to seal the working chamber 10. The axial center of the drive shaft 2 is eccentric from the central axis of the working chamber 10 by a predetermined distance.

As shown in FIG. 1, the inner rotor 3 has a spline hole 31 into which the drive shaft 2 is fitted and fixed, and is rotatably held within the working chamber 10. Both end surfaces of the inner rotor 3 are in sliding contact with the inner end surfaces of the front wall 12 and the rear wall 13, and six trochoid teeth (
A protrusion 33 (as referred to in the present invention) is formed. The outer rotor 4 has an outer circumferential surface 41 that matches the inner circumferential surface of the working chamber 10, and is rotatably housed within the working chamber 10 on the outside of the inner rotor 3 in the radial direction. On the inner periphery of the outer rotor 4 are formed seven arcuate teeth (projections in the present invention) 43 that can mesh with the trochoid teeth 33 of the inner rotor 3.
It is configured to rotate as a result of the rotation of the inner rotor 33.

A plurality of working spaces S are defined between the two rotors 3 and 4 by the meshing of the two rotors 3 and 4, and each working space S is located in the right direction of both the rotors 3 and 4. Due to the rotation, the volume increases continuously during a half rotation from the top position to the bottom position in FIG. 1, and continuously decreases during the subsequent half rotation. A crescent-shaped suction port 5 is recessed in the inner end surface of the rear wall portion 13 in the right half of FIG. 1, and the radial width dimension of this suction port 5 is as shown in FIG. As shown in FIG. This is because the volume of the working space S that communicates with the upper part 51 is small and the volume of the working space S that communicates with the lower part 52 is large, so that oil can be smoothly delivered from the suction port 5 to the working space S. It is.

Similarly, a crescent-shaped discharge port 6 is recessed in the inner end surface of the rear wall portion 13 in the left half of FIG. Furthermore, as shown in FIG. 2, a shallow recess 53 is formed in the inner end surface of the front wall portion 12 at the same position as the suction port 5. The role of this recess 53 is to make the contact areas of the front and rear end surfaces of the rotors 3 and 4 the same, and to balance the pressure in the thrust direction. Further, the rear wall portion 13 projects upward in FIG. 1 from the central cylinder portion 11 and the front wall portion 12, and the reflux control valve 7 is provided on this projecting portion 13a.

This reflux control valve 7 is shown in FIG.
A spool hole 71 is formed horizontally from the right end of the projecting portion 13a, and after accommodating a spool 72 and a coil spring 73, the spool hole 71 is sealed by screwing a stopper 74 into the spool hole 71. ing. A suction port 75 and a discharge port 76 are opened at predetermined positions in the spool hole 71, and the coil spring 73 urges the spool 72 to the left in FIG. and are blocked. Reflux control valve 7
The suction port 75 communicates with the discharge port 6 via the discharge passage 8, and the suction port 75 communicates with the actuator (for example, the hydraulic pressure shown in FIG. motor). A spring chamber 79 defined in the spool hole 71 by the plug 74 and the spool 72 is supplied with high-pressure oil from the discharge port 78 through the throttle 80 . The oil is released into the suction passage 90 through the suction passage 90.

The main parts of this embodiment will be explained below. The discharge port 76 of the reflux control valve 7 communicates with the upper part 51 of the suction port 5 through a straight tube-shaped supercharging passage 9, and a suction passage 90 is opened in the middle of this supercharging passage 9, so that the suction Passage 90 draws oil from oil tank 82. Further, the supercharging passage 9 extends obliquely to the axis of the spool hole 71 and substantially coincides with the tangential direction of the upper portion 51 of the suction port 5. Furthermore, as shown in an enlarged view in FIG.
Junction point 99 at the farthest point from the reflux control valve 7
In A, the angle between the extension direction Z of the supercharging passage 9 and the tangential direction Y of the suction port 5 is 20 degrees or less. In this way, the reflux control valve 7 can be brought close to the suction port 5 without sacrificing the length of the supercharging path, reducing the overall height of the pump. - Since the inflow direction of the oil does not suddenly change when entering the port 5, it is possible to prevent pressure loss from occurring due to vortices or turbulence. Moreover, the cross-sectional area Sc of the suction port 5 in the direction perpendicular to the flow line is the junction area 99 with the supercharging passage 9.
The junction point 99A, which is the farthest point from the reflux control valve, is formed to have a cross-sectional area Sm or more of the supercharging passage 9 in a direction perpendicular to the flow line. In this way, the oil flowing into the suction port 5 from the supercharging passage 9 will not be throttled by the suction port 5.

(Operation explanation) In this trochoid pump,
When the inner rotor 3 rotates clockwise in FIG. 1 due to the rotation of the drive shaft 2, the outer rotor 4 is driven to rotate. With this rotation, each working space S formed between the trochoidal teeth 33 and the circular arc teeth 43 of both rotors 3 and 4 communicates with the suction port 5 when its volume increases, and its volume increases. When becomes small, it communicates with the discharge port 6. This allows the suction port to
Fluid is sucked into the working space S from the port 5, pressurized, and discharged from the discharge port 6. By performing the suction and discharge actions by each of the action spaces S,
Oil is discharged from the discharge port 6 through the discharge passage 8 from the actuator discharge port 78 of the reflux control valve 7 at a flow rate corresponding to the rotational speed.

Furthermore, when the discharge pressure discharged from the discharge port 6 increases relative to the pressure inside the spring chamber 79, the spool 72 moves to the right against the coil spring 73, causing the reflux control valve 7 to close. The flow rate of recirculation from the suction port 75 to the discharge port 76 for recirculation increases, thereby preventing an increase in the oil pressure or flow rate supplied to the actuator. In addition, high-pressure oil is returned from the actuator discharge port 78 to the spring chamber 79 through a throttle 80, and even if the discharge pressure increases due to external factors, the spool 72 operates to compensate and the oil is returned to the spring chamber 79. The flow rate is prevented from increasing, so the discharge flow rate does not decrease. Further, by adjusting the opening degree of the proportional electromagnetic valve 81, the return flow rate from the spring chamber 79 to the oil tank 82 is adjusted, thereby adjusting the pressure in the spring chamber 79, and adjusting the recirculation flow rate to a desired value.

The velocity energy of the oil discharged at high speed from the reflux outlet 76 of the reflux control valve 7 to the supercharging passage 9 is gradually converted into pressure energy by a diffuser action in the supercharging passage 9 and the suction port 5. After being converted into , it is sent into the working space S. Oil passes through the supercharging passage 9 near the suction passage 90 at high speed, that is, at low pressure, so that the oil is sucked up from the oil tank 82 into the supercharging passage 9 through the suction passage 90.

As explained above, in this embodiment, since the supercharging passage 9 is installed obliquely, the total length of the supercharging passage 9 can be made longer compared to the ratio of the total height of the pump, and moreover, the supercharging can be carried out without sudden angle changes. Since the passage 9 is directly connected to the suction port 5, pressure energy can also be converted to the suction port 5, resulting in prevention of cavitation, improvement of pump efficiency, reduction of noise, etc. can be fulfilled.

Incidentally, FIG. 4 shows an automobile cooling fan drive system using the trochoid pump of this embodiment. (Modification 1) An embodiment in which the present invention is applied to a general internal gear pump is shown in FIG. This internal gear pump differs from the trochoid pump of the first embodiment in that it includes a fixed crescent 200, but the arrangement and shape of the supercharging passage 9 and its effects are the same.

(Modification 2) An embodiment in which the present invention is applied to a vane pump is shown in FIG. In this vane pump, a rotor 102 is rotatably housed in a working chamber 101 having a cylindrical inner peripheral surface formed in a housing 100.
A plurality of vanes (projections in the present invention) 103 protruding from the rotor 102 in the centrifugal direction define a plurality of action spaces S that gradually expand and then gradually contract.

In FIG. 6, where the working space S is expanded, the suction port 104 is provided in the right half, and the discharge port is provided in the left half.
A port 105 is provided, and the suction port 104 is connected to a supercharging path 106.
Throughout, the discharge port 105 is connected to a reflux control valve 108 through a discharge passage 107. Although a detailed explanation of the operation of this vane pump will be omitted, the position and shape of the supercharging passage 9 and its effects are similar to those of the trochoid pump of the first embodiment.

[Brief explanation of the drawing]

FIG. 1 is a radial cross-sectional view (A-A line) of a trochoid pump as an embodiment of the present invention;

FIG. 2 is an axial cross-sectional view of the trochoid pump in FIG. 1;

[Fig. 3] An enlarged explanatory diagram of the main parts of the pump in Fig. 1;

FIG. 4 is a hydraulic system diagram showing an automotive ventilation system using the trochoid pump of FIG.

FIG. 5 is an explanatory diagram showing a cross-sectional view of a radial main part of an internal gear pump as another embodiment of the present invention;

FIG. 6 is an explanatory diagram showing a radial cross-sectional view of a vane pump as another embodiment of the present invention.

[Explanation of symbols]

10 is a working chamber, 1 is a casing, 3 is an inner rotor (rotor), S is a working space, 33 is a trochoid tooth (protruding part)
, 5 is the suction port, 6 is the discharge port, 7 is the reflux control valve, 9 is the supercharging path

Claims (3)

[Claims] 1. A casing having a cylindrical working chamber formed therein; a rotor rotatably supported within the working chamber;
a plurality of protrusions projecting from the rotor in a substantially centrifugal direction to define a plurality of working spaces in the working chamber, and continuously changing the volume of each working space through rotation; and a side of the working chamber. A suction port and a discharge port are respectively recessed at predetermined positions on the inner end surface of the casing that partitions the end surface, and are arranged in an arc shape around the axis of the rotor; a reflux control valve that controls the reflux of a portion of the working fluid discharged from the port to the suction port; a reflux discharge port of the reflux control valve is in communication with the suction port; a supercharging passage for supplying working fluid to the suction port, and the flow line direction of the supercharging passage substantially coincides with the tangential direction of the arc-shaped suction port so that the supercharging passage and the A rotary pump characterized by being formed so that it is smoothly continuous with a suction port. 2. The rotary pump according to claim 1, wherein the supercharging passage has a straight pipe shape extending obliquely to the longitudinal direction of the reflux control valve. 3. The cross-sectional area of the suction port in the direction perpendicular to the streamline is larger than the cross-sectional area of the supercharge passage in the direction perpendicular to the streamline in the vicinity of the joint with the supercharge passage. The rotary pump according to claim 1.