JP4484679B2 - Internal gear pump - Google Patents

Description

  The present invention relates to an improvement of an internal gear pump that supplies hydraulic pressure to an assist hydraulic power cylinder of an automobile anti-lock brake system or a power steering device, for example.

  For example, as an internal gear pump used in an automobile, an outer rotor integrally formed with a plurality of inner teeth on the inner peripheral side and a plurality of outer teeth meshing with the inner teeth on the outer peripheral side are integrally formed. Among the plurality of pump chambers formed between the inner teeth and the outer teeth, one pump chamber sandwiching the confining portion with the largest volume communicates with the suction port region, The other pump chamber communicates with the discharge port region.

  In the pump chamber on the discharge side, the pump discharge pressure acts in the direction in which the outer rotor is separated from the inner rotor, and therefore, the inner teeth of the outer rotor and the outer teeth of the inner rotor in the confinement portion. The meshing gap (tip clearance) between both tooth crests becomes large, and the hydraulic oil in the high-pressure discharge-side pump chamber leaks into the low-pressure suction-side pump chamber, resulting in a decrease in pump efficiency. Yes.

  Therefore, in the internal gear pump described in Patent Document 1 below, the outer peripheral side of the outer rotor on the discharge side is provided with both side surfaces of the outer rotor and opposing surfaces of the first and second side plates. A high-pressure passage that introduces high-pressure oil that leaks in the radial direction from the gap (side clearance) is provided, while a low-pressure introduction passage that introduces suction pressure (low pressure) is provided on the outer periphery of the outer rotor on the suction side. The outer rotor is pressed toward the closed portion by the high pressure in the passage and the low pressure in the low pressure introduction passage.

  As a result, the tip clearance between the inner teeth and the outer teeth on the side of the confinement portion is reduced, and the leakage of hydraulic oil from the discharge side pump chamber to the suction side pump chamber is prevented.

A seal member is provided on the inner peripheral side wall surface of the cam ring, and the seal member seals between the high pressure side (discharge side) and the low pressure side (suction side).
Japanese Patent Application Laid-Open No. 11-117876

  However, in the conventional internal gear pump, the seal member provided on the inner peripheral side wall surface of the cam ring is always in sliding contact with the outer peripheral surface of the outer rotor, so that it slides when the pump is driven to rotate. It becomes resistance.

  As a result, the pump efficiency deteriorates and the seal member may be worn and damaged over time.

The present invention has been devised in view of the technical problems of the conventional internal gear pump, and includes an annular cam ring and first and second side plates provided on both sides in the axial direction of the cam ring. And a housing having a working chamber therein, and is housed on the inner peripheral side of the cam ring so as to be slidable with respect to the inner peripheral surface of the cam ring. An outer rotor formed on the inner circumferential side of the outer rotor, and an outer rotor on which outer teeth meshing with the inner teeth are continuously formed on the outer circumferential side, and the inner rotor An axis that connects a drive shaft that rotates in the forward and reverse directions and a confining portion having a maximum volume and a meshing portion having a minimum volume among a plurality of pump chambers formed between the inner teeth and the outer teeth. Symmetrical about The first port and the second port that open to the plurality of pump chambers, and the sliding contact surface with the outer rotor on the inner peripheral surface of the working chamber, and provided on the side of the confining portion, A first oil groove communicating with the port; a first communication passage communicating the first port with the first oil groove; provided in the first communication path, from the first port side to the first oil groove side The first check valve that allows the pump oil to flow into the sliding surface of the inner circumferential surface of the working chamber with the outer rotor and provided on the side of the closing portion, and communicates with the second port. A second oil groove, a second communication path communicating the second port and the second oil groove, and pump oil provided in the second communication path from the second port side to the second oil groove side and a second check valve that allows the flow, the first, the second communication passage, said first side plate or the second support And forming the interior of the de-plate, an opening facing the respective oil groove side of each of the communication passage, is characterized by formed by offset from said formation position of the oil groove toward the outer periphery of the cam ring .

  According to the present invention, when the second port side becomes the suction side and the first port side becomes the discharge side due to, for example, forward rotation driving of the drive shaft, the high-pressure oil of the first port becomes the first communication path. To the first oil groove. The high-pressure oil supplied to the first oil groove gives a pressing force that urges the outer rotor from the closed portion side to the meshing side.

  For this reason, the meshing force between the inner rotor and the outer rotor at the confinement portion is increased, and the chip clearance can be sufficiently reduced.

  Further, since the high pressure oil leaking to the second communication path side through the space between the working chamber surface and the outer rotor is blocked from flowing into the second port side by the second check valve, Leakage from the (first communication path) to the low pressure side (second communication path side) can be minimized. As a result, pump efficiency can be improved.

In particular, according to the present invention, the openings of the first and second communication passages are offset from the oil grooves, so that the first or second communication passage is supplied from the discharge side. Since the high-pressure oil once hits the end face of the cam ring that closes the opening and then is supplied into each oil groove, the pulsation is attenuated by the collision with the end face of the cam ring that faces the opening, and Pressure pulsation can be reduced.

DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment of an internal gear pump according to the present invention will be described in detail with reference to the drawings. The internal gear pump provided in the present embodiment is applied to a trochoid pump capable of forward and reverse rotation that selectively supplies hydraulic pressure to both hydraulic chambers of an assist hydraulic cylinder of a vehicle power steering apparatus.

  That is, as shown in FIGS. 1 and 2, the internal gear pump includes an annular working chamber 2 formed on an inner peripheral side of a cam ring 12 (described later) constituting a part of the housing 1, and the working chamber 2. The outer rotor 3 is rotatably accommodated in the inner periphery, and a plurality of inner teeth 3a are continuously formed in the circumferential direction on the inner peripheral side, and the outer rotor 3 is rotatably provided on the inner peripheral side of the outer rotor 3. The outer teeth 4a meshing with the inner teeth 3a continuously formed in the circumferential direction, the drive shaft 5 for driving the inner rotor 4 to rotate forward and reverse, the inner teeth 3a and the outer teeth 4a, Among the plurality of pump chambers 6 formed between the first port 7 and the second port 7 provided symmetrically about an axis X connecting a confining portion having a maximum volume and a meshing portion having a minimum volume, which will be described later. Port 8. The first and second ports 7 and 8 are formed so that the suction side and the discharge side are relatively opposite to each other when the rotors 3 and 4 are rotated forward and backward. The second port 8 is on the suction side and the first port 7 is on the discharge side in the direction of the solid arrow, and on the opposite side during reverse rotation (in the direction of the broken arrow in FIG. 2).

  The housing 1 is accommodated and disposed in a reservoir tank 9 as a whole, a first side plate 10 made of a block-like aluminum alloy connected to the reservoir tank 9 by a bolt (not shown), and one of the first side plates 10. A second side plate 11 fixed to a side surface by a bolt (not shown) and facing the reservoir tank 9, and a substantially cylindrical cam ring 12 disposed between the side plates 10 and 11. Has been.

  Each side plate 10, 11 has a bolt insertion hole 13 through which the bolt is inserted at the four corners on the outer peripheral side.

  The first side plate 10 has one end portion of the drive shaft 5 rotatably inserted through a bearing 14 in a shaft hole 10a formed substantially at the center, and the first side plate 10 and the first port 7 Discharge passages 15 and 16 connected to the second port 8 are formed. The discharge passages 15 and 16 communicate with both selected hydraulic chambers of the hydraulic cylinder on the downstream side.

  The second side plate 11 is formed in a thin block shape by an aluminum alloy material, and the other end portion of the drive shaft 5 is rotatably inserted and supported through a bearing 17 in a shaft hole 11a formed substantially at the center. In addition, suction passages 18 and 19 connected to the first and second ports 7 and 8 are formed. The suction passages 18 and 19 communicate with the interior of the reservoir tank 9.

  Further, a minute side clearance for ensuring the rotation of the outer rotor 3 is formed between the opposing surfaces of the first side plate 10 and the second side plate 11 and both side surfaces of the outer rotor 3. .

  The cam ring 12 is formed in an annular shape by a sintered alloy having a predetermined thickness, the center position thereof is decentered by a predetermined amount from the center of the inner rotor 4, and the outer peripheral surface is in the reservoir tank 9. It faces. Further, an annular minute gap for ensuring the rotation of the outer rotor 3 is formed between the inner peripheral surface 12 a of the cam ring 12 (inner peripheral surface of the working chamber 2) and the outer peripheral surface 3 b of the outer rotor 3. ing.

  As shown in FIG. 2, the outer rotor 3 and the inner rotor 4 have an internal tooth 3 a and an outer tooth on the axis X connecting the first port 7 and the second port 8 with respect to forward rotation (solid arrow). The part where each tooth crest of the tooth 4a contacts is the closed part 20, and the left and right pump chambers 6a, 6b on both sides of the closed part 20 are set to have a maximum volume. Then, the communication between the respective pump chambers 6a and 6b and the ports 7 and 8 is blocked.

  Further, during the forward rotation, the inner teeth 3a and the outer teeth 4a located on the side opposite to the closing portion 20 on the axis X are sufficiently meshed with each other in the meshing portion 21 where the pump chamber 6 has a minimum pump volume. It has become.

  The closed portion 20 and the meshing portion 21 are formed on the opposite sides of FIG. 2 when the rotors 4 and 5 are driven to rotate in the reverse rotation direction (broken arrows).

  The drive shaft 5 is rotationally driven in the forward and reverse directions by an electric motor (not shown). For example, the inner rotor 4 and the outer rotor 3 are rotated in the same direction by a forward rotational driving force to increase the volume of the pump chamber 6. The hydraulic oil is sucked from the second port 8 area while increasing / decreasing, and the hydraulic oil is discharged to the discharge passage 15 in the first port 7 area that has passed through the confining portion 20 having the maximum volume. On the other hand, the hydraulic oil is sucked from the first port 7 area by the rotational driving force of the reverse rotation, and the hydraulic oil is discharged to the discharge passage 16 in the second port 8 area from the closed portion 20 on the opposite side which is maximized. It has become.

  Further, the first port 7 or the vicinity of the inner peripheral surface of the cam ring 12 that becomes the closing portion 20, that is, the vicinity of the closing portion 20 described above when the rotors 3 and 4 rotate forward or backward. First and second oil grooves 22 and 23 communicating with the second port 8 are formed.

  Each of the oil grooves 22 and 23 is formed at a substantially X-axis symmetric position across the axis X, and is set to a predetermined short length in the circumferential direction of the cam ring 12 as shown in FIGS. In addition, the cam ring 12 is formed in a penetrating state in the axial direction.

  Further, the first side plate 10 has first and second communication passages 24 communicating with the oil grooves 22 and 23 and the first port 7 or the second port 8 on the discharge side according to forward and reverse rotation. , 25 are formed.

  Since the first and second communication passages 24 and 25 have the same configuration, for convenience, only the first communication passage 24 will be described with reference to FIG. 1. The first side plate 10 is formed in a linear shape having a relatively small diameter inside the first side plate 10. The upstream end 24a is connected to the discharge passage 15, while the downstream opening 24b is formed in a relatively large-diameter circular shape on the end surface of the first side plate 10 on the cam ring 12 side. An opening is formed, and the first oil groove 22 is formed in an offset state in the radial direction of the cam ring 12.

  Accordingly, the upper surface of the opening 24b excluding the first oil groove 22 is closed by a side end surface of the cam ring 12, that is, an upper wall surface of a communication groove 29 described later.

  The opening 24 b is provided with a first check valve 26 that allows high-pressure oil to flow only from the first communication passage 24 toward the first oil groove 22.

  The first check valve 26 includes a substantially cylindrical ball accommodating portion 27 formed in the opening 24a and a first reaming valve that is movably accommodated in the ball accommodating portion 27 and faces the opening 24b. The ball valve body 28 is configured to be separated from and seated on the opening edge of the small-diameter passage portion of the passage 24 to open and close the opening.

  Further, as shown in FIG. 3, a communication groove 29 that communicates the downstream opening 24 b and the first oil groove 22 is formed on the side end surface of the cam ring 12 facing the opening 24 b of the first communication passage 24. Is formed. The communication groove 29 is formed in an arc shape substantially the same as the inner diameter of the opening 24b.

  A second check valve 30 and a communication groove 29a having the same configuration as the first check valve 26 are also provided in the downstream opening 25b of the second communication passage 25 outside the figure.

Further, the symmetric position of the first oil groove 22 and the second oil groove 23 of the cam ring 12, the third, fourth oil groove 31 is formed that is penetrated by similarly along the axial direction of the cam ring 12 ing.

  Further, in FIG. 1, reference numerals 33 and 34 are provided in the suction passages 18 and 19, respectively, to allow the hydraulic oil in the reservoir tank 9 to flow only in the direction of the ports 7 and 8 on the suction side. It is a valve.

  Therefore, in this inscribed gear pump, when both the rotors 3 and 4 are rotated in one direction by rotating the electric motor in, for example, the normal rotation direction, the pumps are connected from the second port 8 on the suction side. When hydraulic oil is sucked into the room and passes through the confining portion 20 and high pressure oil is discharged from the first port 7 to the first discharge passage 15, a part of the high pressure oil is upstream of the first communication passage 24. The ball valve body 28 flows in from the inside 24a, and the ball valve body 28 is pushed open by hydraulic pressure, flows into the communication groove 29 from the opening 24b, and is further supplied into the first oil groove 22 from here.

  The cam ring 12 presses the outer rotor 4 toward the meshing portion 21 by the high-pressure oil supplied to the first oil groove 22. For this reason, the pressure contact force of the inner and outer teeth 3a and 4a at the closing portion 20 is increased, and the chip clearance can be reduced. Therefore, it is possible to sufficiently prevent the hydraulic oil from leaking from the high-pressure discharge-side pump chamber 6a to the low-pressure suction-side pump chamber 6b in the closing portion 20.

Further, high pressure oil discharged from the opening 24b to the communicating groove 2 9, since the flow into the first oil groove 22 collides once the wall surface on the該連Tsumizo 2 9, wherein the pulsation of the high-pressure oil As a result, the first oil groove 22 can be supplied with hydraulic pressure with sufficiently reduced pressure pulsation. As a result, the occurrence of vibration of the cam ring 12 can be prevented. Further, the high-pressure oil flowing into the communication groove 29 is smoothly supplied from the communication groove 29 into the first oil groove 22 while suppressing pulsation as described above.

On the other hand, the hydraulic oil that has flowed into the second oil groove 23 through the space between the inner peripheral surface of the cam ring 12 and the outer peripheral surface of the outer rotor 3 passes through the communication groove 29a from the downstream opening to the second communication passage. The small diameter opening of the second communication passage 25 is closed by the ball valve body of the second check valve 30, so that the inflow from the second communication passage 25 to the second port 8 side. Is definitely prevented. For this reason, it becomes possible to suppress the leakage from the high pressure side (the first communication path 24 side) to the low pressure side (the second communication path 25 side) to the minimum. As a result, pump efficiency can be improved.

  When each of the rotors 3 and 4 is reversely driven by an electric motor, the high-pressure oil is supplied to the second oil groove 23 side via the second communication passage 25, so that the rotor is closed. It is possible to sufficiently reduce the tip clearance between the inner and outer teeth 3a, 4a on the part side, and this time the first check valve 26 leaks from the first oil groove 22 to the first communication path 24. Oil inflow can be reliably prevented.

Further, when the cam ring 12 is formed of a sintered alloy and is removed from the mold, the third and fourth oil grooves 31 and 32 are also provided together with the first oil groove 22 and the second oil groove 23. Since the molding can be performed, the molding operation of the oil grooves 22, 23, 31, 32 is facilitated, and the cutting and polishing of the oil grooves are facilitated.

  Further, in this embodiment, the openings 24b and 25b, that is, the respective ball receiving portions 27 are closed except for the first and second oil grooves 22 and 23 by the upper wall surfaces of the communication grooves 29 and 29a. There is no possibility that each ball valve body 28 jumps out. In addition, since the ball valve body 28 can be easily put into the ball accommodating portion 27 from the opening 24b side when assembling each constituent member, the assembling workability is improved.

  The technical ideas other than the invention described in the claims, as grasped from the embodiment, will be described below.

  (1) At least the first check valve is accommodated in a ball accommodating portion provided in the opening, and is movably accommodated in the ball accommodating portion, and the diameter of the first communication passage on the opening side is reduced. The internal gear pump according to claim 3, wherein the internal gear pump comprises a ball valve body that opens and closes a hole.

  Since the opening is formed at a position offset from the oil groove and the inside of the opening is closed by the end face of the cam ring except for the portion communicating with the oil groove, the ball accommodated in the ball accommodating portion There is no risk of the valve body popping out. In addition, since the ball valve body can be easily put into the ball housing portion from the opening side when assembling each constituent member, the assembling workability is improved.

  (2) The inscribed type according to (1), wherein a communication groove communicating with the opening and the oil groove is formed on an end surface of the cam ring facing the opening. Gear pump.

  According to the present invention, the high-pressure oil that has passed through the openings from the first and second communication paths once hits the end face of the cam ring and is smoothly supplied from the communication grooves into the oil grooves as it is.

  The present invention is not limited to the configuration of the above-described embodiment. For example, the housing may be configured by a housing body and a rear cover instead of the first and second side plates.

  Moreover, although the said embodiment demonstrated the case where each rotor 3 and 4 rotationally drives forward / reversely, it is applicable also to the pump which rotationally drives only to one direction. It is also possible to form the working chamber 2 directly in the housing 1.

  Furthermore, it is also possible to apply such an inscribed gear pump to a brake device as in the prior art.

It is the sectional view on the AA line of FIG. 2 which shows one Embodiment of the internal gear pump which concerns on this invention. It is a front view of the internal gear pump which removed the 2nd side plate. It is a perspective view of the cam ring provided for this embodiment. .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Housing 2 ... Working chamber 3 ... Outer rotor 4 ... Inner rotor 5 ... Drive shaft 6 ... Pump chamber 7 ... 1st port 8 ... 2nd port 10 ... 1st side plate 11 ... 2nd side plate 12 ... Cam ring 20 ... Enclosed portion 21 ... meshing portion 22 ... first oil groove 23 ... second oil groove 24 ... first communication passage 24b ... opening 25 ... second communication passage 25b ... opening 26 ... first check valve 27 ... ball accommodation Part 28 ... Ball valve element 29 ... Communication groove X ... Axis

Claims (1)

A housing formed by an annular cam ring and a first side plate and a second side plate provided on both sides in the axial direction of the cam ring, and having a working chamber inside ;
An outer rotor that is slidably accommodated on the inner peripheral side of the cam ring with respect to the inner peripheral surface of the cam ring, and on the inner peripheral side, a plurality of internal teeth are continuously formed in the circumferential direction;
An inner rotor that is rotatably provided on the inner peripheral side of the outer rotor, and has outer teeth that continuously engage with the inner teeth on the outer peripheral side;
A drive shaft for rotationally driving the inner rotor in forward and reverse directions;
Among the plurality of pump chambers formed between the inner teeth and the outer teeth, the plurality of pump chambers are provided symmetrically about an axis connecting a confining portion having a maximum volume and a meshing portion having a minimum volume. A first port and a second port opening into the chamber;
A first oil groove provided on the side of the confining portion on the sliding surface of the inner circumferential surface of the working chamber with the outer rotor, and communicating with the first port;
A first communication passage communicating the first port and the first oil groove;
A first check valve provided in the first communication passage and allowing the pump oil to flow from the first port side to the first oil groove side;
A second oil groove provided on the side of the confining portion on the sliding contact surface of the inner circumferential surface of the working chamber with the outer rotor, and communicating with the second port;
A second communication passage communicating the second port and the second oil groove;
A second check valve provided in the second communication path and allowing the flow of pump oil from the second port side to the second oil groove side ,
The first and second communication passages are formed in the first side plate or the second side plate, and an opening facing the oil groove side of each communication passage is formed at each oil groove formation position. An internal gear pump characterized by being offset from the outer periphery of the cam ring .

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