JP2015052281A - Oil pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To inhibit frictional resistance which is caused between a pump rotor/a pump body and a pump head cover in an axial thrust direction.SOLUTION: An inscribed gear type trochoid pump 10 includes: an inner rotor 12A disposed on a drive shaft 14; a pump head cover 11A which closes a pump rotor housing hole 15 and forms a pump rotor housing part; and a suction port 17 and a discharge port 18 which are formed in at least one of a pump body 11B and the pump head cover 11A. A thin plate-like plane part 19 is provided on an end surface of an outer rotor 12B which faces the pump rotor housing hole 15, and the inner rotor 12A is held in a space formed by an inner rotor housing chamber 16 and the thin plate-like plane part 19.

Description

  The present invention relates to a rotor and a case of an inscribed gear pump.

  2. Description of the Related Art Conventionally, an internal gear type oil pump is known as a pump used in an automobile hydraulic circuit or the like. As an example, a trochoid pump is shown in FIG.

  The pump body 11 of the trochoid pump 10 is formed by a pump head cover 11A and a pump body 11B, and a circular pump rotor housing hole 15 is formed in the pump body 11B. The pump rotor housing hole 15 houses an inscribed gear type pump rotor 12, and the pump rotor 12 is constituted by an inner rotor 12A and an outer rotor 12B.

  The outer rotor 12 </ b> B is formed in a columnar shape and is rotatably accommodated in the pump rotor accommodation hole 15. The outer rotor 12B is formed with an inner rotor storage chamber 16 for storing the inner rotor 12A. The inner rotor storage chamber 16 has star-shaped inner teeth.

  The inner rotor 12 </ b> A also has star-shaped outer teeth and is rotatably accommodated in the inner rotor storage chamber 16. A drive shaft 14 is connected to the inner rotor 12 </ b> A and is configured to be rotated by the drive shaft 14.

  The number of inner teeth of the inner rotor storage chamber 16 is set to be larger than the number of outer teeth of the inner rotor 12A. As a result, when the inner rotor 12A is rotated together with the outer rotor 12B by the drive shaft 14, the volume of the space formed between the inner rotor 12A and the outer rotor 12B as shown in FIG. The oil is sucked from the suction port 17 by using this volume change, and is configured to be discharged from the discharge port 18.

Next, as a method of reducing the frictional resistance in sliding of the pump rotor in these internal gear type oil pumps, as shown in FIGS. 6 (a) and 6 (b), it is accommodated in the pump rotor accommodation hole 15 of the pump body 11B. The pump rotor 12 is rotated and oil sucked from the suction port 17 is discharged in the circumferential direction to at least one of the outer peripheral surface of the outer rotor 12B and the inner peripheral surface of the pump body 11B that are in sliding contact with each other when the oil discharged from the discharge port 18 is discharged. An elongated belt-like groove 60 is provided and the sliding contact area is reduced by the area occupied by the groove 50. (See Patent Document 1)
Another method is shown in FIGS. 7 (a), (b), and (c). A substantially crescent-shaped intake port 27 and discharge port 28 are formed on the bottom surface of the pump rotor accommodation hole 15 of the pump body 11B. The suction port 27 and the discharge port 28 are also provided in the pump head cover 11A (not shown) and communicate with the suction port 17 and the discharge port 18, respectively. Side oil pressure that equalizes the oil pressure acting on the suction port 17 formed in at least one of the pump body 11B and the pump head cover 11A, and both side surfaces near the outer peripheral portion of the discharge port 18 and the outer rotor 12B in the axial thrust direction. The thing provided with the equalization means 70 is proposed. (See Patent Document 2)

JP 2011-214553 A JP 2007-23975 A

  However, if the belt-shaped groove 60 extending in the circumferential direction is provided in at least one of the outer peripheral surface of the outer rotor 12B and the inner peripheral surface of the pump body 11B, the frictional resistance in the circumferential direction is reduced. There is a problem that the frictional resistance in the axial thrust direction, which accounts for most of the frictional resistance in sliding of the pump, is still large.

  In addition, as shown in FIG. 7 (a), the one provided with the above-described side hydraulic pressure equalizing means 70 has a substantially crescent-shaped suction port 27 and a discharge port 28, and a suction port 17 and a discharge port 18 respectively communicating with each other. Is considered to be effective when positioned on the outer peripheral side in the radial direction, but when the suction port 17 and the discharge port 18 are positioned directly above the pump rotor 12, as shown in FIG. Since the pump rotor 12 directly receives the discharge pressure, the pump rotor 12 is inevitably pushed into the opposite discharge port side and easily slides on the bottom surface of the pump rotor accommodation hole 15 of the pump body 11B. There is a problem that tends to increase.

  The present invention has been made to solve such problems, and an object of the present invention is to provide an oil pump that has a simple configuration and suppresses frictional resistance in the axial thrust direction of the pump rotor.

  In order to achieve the above object, the present invention according to claim 1 includes a pump body 11B having a cylindrical concave pump rotor housing hole 15 having a center axis at a position eccentric to the drive shaft 14, and an annular shape. The outer rotor 12B is formed and is rotatably accommodated in the cylindrical concave pump rotor accommodating hole 15, and has an outer rotor 12B having inner teeth in the inner rotor accommodating chamber 16, and outer teeth meshing with the inner teeth of the outer rotor 12B. The inner rotor 12A disposed on the drive shaft 14, the pump head cover 11A that closes the pump rotor housing hole 15 to form a pump rotor housing portion, and at least one of the pump body 11B and the pump head cover 11A are formed. In an internal gear type trochoid pump 10 having a suction port 17 and a discharge port 18, Oil having a configuration in which a thin plate-like flat portion 19 is provided on an end surface facing the protor housing hole 15 and the inner rotor 12A is held in a space formed by the inner rotor storage chamber 16 and the thin plate-like flat portion 19. In the pump.

  The present invention according to claim 2 includes an outer rotor outer end surface 20 that is a surface facing the pump body 11B of the thin flat plate portion 19 of the outer rotor 12B, and a pump body bottom surface 23 that is a surface facing the outer rotor outer end surface 20 of the pump body 11B. The oil pump according to claim 1, wherein a taper is provided on at least one of the first and second sides so that the gap decreases in the outer circumferential direction.

  According to the third aspect of the present invention, the outer rotor outer end surface 20 that is the surface facing the pump body 11B of the thin flat plate portion 19 of the outer rotor 12B and the pump body bottom surface 23 that is the surface facing the outer rotor outer end surface 20 of the pump body 11B. And an outer peripheral surface groove 25 communicating with the pump rotor housing hole 15 and at least one of the outer peripheral surfaces of the outer rotor 12B in the axial thrust direction. The oil pump according to claim 1, wherein the oil pump is provided.

  According to a fourth aspect of the present invention, in the oil pump according to the first to third aspects, a hydraulic pressure generating groove 24 is provided in a radial direction on at least one of the outer end surface 20 of the outer rotor and the bottom surface 23 of the pump body. It is in.

  According to the present invention, it is possible to generate an appropriate oil film in the gap between the outer rotor and the pump body, and particularly to effectively suppress the frictional resistance in the axial thrust direction.

(A) Exploded perspective view of oil pump in Embodiment 1 of the present invention (b) Perspective view of outer rotor in Embodiment 1 of the present invention (c) Perspective view of inner rotor in Embodiment 1 of the present invention (d) ) Oil pump plane transparent view in Embodiment 1 of the present invention (e) Functional sectional view of the side surface of the oil pump in Embodiment 1 of the present invention (A) Enlarged view of tapered portion 1 of oil pump in Embodiment 2 of the present invention (b) Enlarged view of tapered portion 2 of oil pump in Embodiment 2 of the present invention (A) Enlarged view of taper portion 1 of oil pump in Embodiment 2 of the present invention (b) Enlarged view of taper portion 2 of oil pump in Embodiment 2 of the present invention (c) Embodiment 2 of the present invention (D) The perspective view of the pump body of the oil pump in Embodiment 2 of this invention (A) Plan view of oil pressure generation groove (spiral groove groove) of oil pump in Embodiment 3 of the present invention (b) Plan view of oil pressure generation groove (herringbone groove) of oil pump in Embodiment 3 of the present invention (A) Pump exploded perspective view of conventional oil pump (b) Outer rotor perspective view of conventional oil pump (c) Inner rotor perspective view of conventional oil pump (d) Pump plan transparent view of conventional oil pump (e) ) Cross-sectional side view of function of conventional oil pump (f) Plan view of rotor showing movement of pump of conventional oil pump (A) Side surface functional sectional view of the oil pump in Conventional Example 1 (b) Plan view of the oil pump in Conventional Example 1 (A) Side sectional view of oil pump in Conventional Example 2 (b) Pump rotor perspective view of oil pump in Conventional Example 2 (c) Pump body perspective view of oil pump in Conventional Example 2

  Hereinafter, the details of the embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
An internal gear type oil pump is provided in, for example, an automatic transmission mounted on a vehicle, and supplies hydraulic oil or lubricating oil to a hydraulic control device of the automatic transmission.

  Fig.1 (a) shows the structure of the trochoid pump 10 in Embodiment 1 of this invention as a disassembled perspective view. In the following embodiments, a trochoid pump will be described as an example of an internal gear type oil pump.

  As shown in FIG. 1A, the trochoid pump 10 includes a pump head cover 11A and a pump body 11B. A circular pump rotor storage hole 15 is formed in the pump body 11, and the pump rotor storage hole 15 is formed. The pump rotor 12 is housed inside.

The pump rotor 12 is composed of an inscribed gear type trochoid gear, and is composed of an inner rotor 12A that is a normal drive gear and an outer rotor 12B that is a driven gear. The outer rotor 12 </ b> B is formed in a columnar shape and is rotatably accommodated in the pump rotor accommodation hole 15. The outer rotor 12B is formed with an inner rotor storage chamber 16 for storing the inner rotor 12A.
Internal teeth are formed in a star shape. The inner rotor 12 </ b> A also has star-shaped outer teeth and is rotatably accommodated in the inner rotor storage chamber 16.

  A drive shaft 14 is connected to the central portion of the inner rotor 12A serving as a drive gear, and is configured to transmit drive torque from a power source such as an electric motor and to be rotated.

  Further, an oil seal 13 for preventing oil leakage is inserted between the drive shaft 14 and the pump body 11B.

  The number of inner teeth of the inner rotor storage chamber 16 is set to be larger than the number of outer teeth of the inner rotor 12A. As a result, when the inner rotor 12A is rotated together with the outer rotor 12B by the drive shaft 14, the volume of the space formed between the inner rotor 12A and the outer rotor 12B as shown in FIG. The oil is sucked from the suction port 17 by using this volume change, and is configured to be discharged from the discharge port 18.

  The material of the component parts is that the pump head cover 11A and the pump body 11B are die-cast aluminum, the inner rotor 12A constituting the pump rotor 12, the outer rotor 12B is an iron-based sintered soft magnetic material, and the drive shaft 14 is carbon. The steel and oil seal 13 is made of a rubber material considering heat resistance and oil resistance.

  By the way, in such a conventional trochoid pump 10, frictional resistance due to sliding between the pump rotor 12 and the pump main body 11 accounts for most of the pump loss. In particular, the frictional resistance due to sliding in the axial thrust direction between the pump rotor 12 and the pump rotor housing hole 15 occupies most. Among them, the frictional resistance due to the sliding in the axial thrust direction between the outer rotor 12B and the pump rotor housing hole 15 accounts for the majority. This is because the pump rotor 12 is directly subjected to the discharge pressure, so that the pump rotor 12 is pushed to the side opposite to the discharge port, and the frictional resistance with the bottom surface of the pump rotor housing hole 15 of the pump body 11B increases.

  As a method of suppressing the frictional resistance caused by sliding in the axial thrust direction, there is a method of increasing the axial thrust direction clearance between the pump rotor 12 and the pump rotor housing hole 15, but in this case, the amount of oil leakage from the clearance is small. Since it increases, the pump efficiency tends to deteriorate.

  Next, a detailed configuration of the present embodiment for suppressing such frictional resistance will be described. In the present embodiment, in order to suppress such frictional resistance caused by sliding between the pump rotor 12 and the pump rotor housing hole 15 in the axial thrust direction, the end surface of the outer rotor 12B facing the pump rotor housing hole 15 is a thin plate. A plane portion 19 is provided, and the inner rotor 12A is held in a space formed by the inner rotor storage chamber 16 and the thin plate-like plane portion 19. In addition, it is desirable that the bottom surface of the pump rotor housing hole 15 has a substantially planar shape in order to form an oil film described later.

  FIG.1 (e) is a functional sectional view which shows arrangement | positioning of the component of this invention pump, and the flow of oil.

  First, the main oil passage relating to the oil protrusion, which is the main function of the pump, will be described. As indicated by arrows in the figure, the oil sucked from the suction port 17 is caused by the volume change of the space formed between the inner rotor 12A and the outer rotor 12B as shown in FIG. It is discharged from the discharge port 18.

  Next, an auxiliary oil passage that guides oil to form an oil film in the gap between the outer rotor 12B and the pump body 11B will be described. Part of the discharged oil passes through the auxiliary groove 26 provided in the pump head cover 11A, passes through the side gap of the fitting hole between the inner rotor 12A and the drive shaft 14, passes through the outer rotor outer end face 20, and the pump body bottom face. Since the flow is directed toward the outer periphery and flows toward the outer periphery, the flow velocity stalls in the gap near the side wall of the pump rotor housing hole 15, the inflow amount becomes larger than the outflow amount, and the outer rotor 12B is moved to the pump head cover 11A side. An oil film is formed that generates pressure to push up. Thereafter, the air passes through the gap between the outer peripheral surface of the outer rotor 12 </ b> B and the side wall of the pump rotor housing hole 15, and is circulated to the suction port 17 or the discharge port 18.

  Since the reaction force of the discharge pressure is constantly applied to the pump rotor 12, the outer end surface 20 of the outer rotor is pressed against the bottom surface 23 of the pump body and the frictional resistance due to sliding is increased. Since an oil film that generates pressure to push the rotor 12B toward the pump head cover 11A is formed, frictional resistance due to sliding is greatly suppressed.

(Embodiment 2)
FIGS. 2A and 2B are enlarged cross-sectional views of the outer rotor 12B and the pump body 11B, which are components of the trochoid pump 10 according to the second embodiment of the present invention.

  In the present embodiment, at least the outer rotor outer end surface 20 that is the pump body 11B facing surface of the thin plate-like flat portion 19 of the outer rotor 12B and the pump body bottom surface 23 that is the outer rotor outer end surface 20 facing surface of the pump body 11B. On the other hand, a taper is provided so that the gap becomes smaller in the outer circumferential direction.

  According to this embodiment, since the gap becomes smaller in the outer circumferential direction, the outlet is narrower than the inlet, and the inflow amount of oil is larger than the outflow amount. Therefore, as in the first embodiment described above. In addition, since an oil film that generates pressure to push the outer rotor 12B toward the pump head cover 11A is formed, frictional resistance due to sliding is greatly suppressed.

(Embodiment 3)
3 (a), (b), (c), and (d) are an enlarged cross-sectional view and a perspective view of the outer rotor 12B and the pump body 11B that are components of the trochoid pump 10 according to Embodiment 3 of the present invention. Is shown.

  In the present embodiment, it is assumed that the oil flows in a direction opposite to the oil flow in the auxiliary oil passage in the first and second embodiments. Therefore, the auxiliary groove 26 provided in the pump head cover 11 </ b> A communicates with the suction port 17. (Not shown) In addition, at least an outer rotor outer end surface 20 that is a surface facing the pump body 11B of the thin flat plate portion 19 of the outer rotor 12B and a pump body bottom surface 23 that is a surface facing the outer rotor outer end surface 20 of the pump body 11B. On the other hand, a taper is provided so that the gap becomes smaller in the inner circumferential direction. Further, since the oil flow in the direction opposite to that in the auxiliary oil passage in the first and second embodiments is positive, oil is positively applied to the gap between the outer peripheral surface of the outer rotor 12B and the side wall of the pump rotor housing hole 15. In order to guide, an outer peripheral surface groove 25 communicating in the axial thrust direction is provided in at least one of the pump rotor accommodation hole 15 and the outer peripheral surface of the outer rotor 12B.

According to this embodiment, since the gap is reduced in the inner circumferential direction, the outlet is narrower than the inlet, and the inflow amount of oil is larger than the outflow amount. Alternatively, as in the second embodiment, an oil film that generates pressure to push the outer rotor 12B to the pump head cover 11A side is formed, so that frictional resistance due to sliding is greatly suppressed.

(Embodiment 4)
4 (a) and 4 (b) are plan views of the outer rotor outer end surface 20 of the outer rotor 12B or the pump body bottom surface 23 of the pump body 11B, which are components of the trochoid pump 10 according to the fourth embodiment of the present invention. It is shown.

  In the present embodiment, a hydraulic pressure generating groove 24 is formed on the outer rotor outer end surface 20 or the pump body bottom surface 23.

  As an example of the oil pressure generating groove 24, FIG. 4A illustrates a spiral groove groove 24A, and FIG. 4B illustrates a herringbone groove 24B. The oil pressure generating groove 24 is designed so that the gap becomes smaller toward the outer peripheral side of the outer rotor 12B, the outlet is narrower than the inlet, and the inflow amount of oil is larger than the outflow amount. As in the first to third embodiments, an oil film that generates pressure to push the outer rotor 12B to the pump head cover 11A side is formed, so that frictional resistance due to sliding is greatly suppressed.

  Further, in the present embodiment, the oil flow direction has been described in the direction toward the outer periphery, but when combined with the above-described third embodiment or the like, as a matter of course, the oil flow is directed toward the inner periphery side. Also, the width of the oil pressure generating groove 24 is described as being reversed.

  Further, as common to the inscribed gear type oil pumps according to the first to fourth embodiments described above, there is a frictional resistance caused by sliding between the inner rotor 12A and the pump body 11B as in the prior art. Instead, the inner rotor 12A and the outer rotor inner end face 21 slide. Since the difference in the number of teeth between the inner rotor 12A and the outer rotor 12B is 1, the relative speed difference is very small, and the frictional resistance due to the sliding is very small.

  The present invention can also be applied to tooth forms other than trochoids.

  As described above, when the oil pump of the present invention is used in a vehicle, the frictional resistance due to sliding is greatly suppressed and the efficiency is high, so that the power consumption can be greatly reduced.

  As a result, it is effective in improving the fuel consumption and power consumption of automobiles.

  The present invention is suitable for in-vehicle use as described above, and can be used for other devices that require a highly efficient oil pump.

DESCRIPTION OF SYMBOLS 10 Trochoid pump 11 Pump main body 11A Pump head cover 11B Pump body 12 Pump rotor 12A Inner rotor 12B Outer rotor 13 Oil seal 14 Drive shaft 15 Pump rotor storage hole 16 Inner rotor storage chamber 17 Suction port 18 Discharge port 19 Thin plate-shaped flat part 20 Outer Rotor outer end surface 21 Outer rotor inner end surface 22 Inner rotor outer end surface 23 Pump body bottom surface 24 Hydraulic pressure generating groove 24A Spiral groove groove 24B Herringbone groove 25 Outer peripheral surface groove 26 Auxiliary groove 27 Suction port 28 Discharge port 60 Band-shaped groove 70 Side surface hydraulic pressure equality Means

Claims (4)

A pump body having a pump rotor housing hole formed at a position eccentric with respect to the drive shaft as a central axis; an outer rotor which is rotatably housed in the pump rotor housing hole and has internal teeth; and the outer rotor An inner rotor disposed on the drive shaft, a pump head cover that closes the pump rotor housing hole to form a pump rotor housing portion, and is formed on the pump head cover. In the inscribed gear type oil pump having a suction port and a discharge port, a thin plate-like flat portion is provided on an end surface of the outer rotor facing the pump rotor storage hole, and the inner rotor storage chamber and the thin plate-like flat surface are provided. An oil pump characterized in that the inner rotor is held in a space constituted by a portion. A gap in the outer circumferential direction is provided on at least one of the outer rotor outer end surface that is the pump body facing surface of the thin plate-like flat portion of the outer rotor and the pump body bottom surface that is the outer rotor outer end surface facing surface of the pump body. The oil pump according to claim 1, wherein a taper is provided so as to reduce the pressure. At least one of the outer rotor outer end surface of the outer rotor and the pump body bottom surface of the pump body is provided with a taper so that a gap is reduced in the inner circumferential direction, the pump rotor housing hole, and the outer rotor 2. The oil pump according to claim 1, wherein an outer peripheral surface groove communicating in the axial thrust direction is provided on at least one of the outer peripheral surfaces of the oil pump. The oil pump according to any one of claims 1 to 3, wherein a hydraulic pressure generating groove is provided in a radial direction on at least one of the outer end surface of the outer rotor and the bottom surface of the pump body.

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