JP5257342B2 - Rotary pump - Google Patents

Description

  The present invention relates to a rotary pump.

  Conventionally, an internal gear type rotary pump that pumps fluid such as oil is known. This is because an inner rotor having outer teeth on the outer periphery and an outer rotor having inner teeth on the inner periphery are arranged eccentrically in a state where the outer teeth and the inner teeth mesh with each other. By rotating, the volume of the gap formed between the outer teeth and the inner teeth changes, and the liquid is sucked and discharged. This is a so-called “trochoid (registered trademark)” type pump.

Here, since the inner rotor is rotated by being transmitted with a driving torque from a shaft that is a rotational drive shaft, the shaft and the inner rotor need to be coupled coaxially.
Patent Document 1 discloses a “press-fit” rotary pump in which a shaft is press-fitted into an inner rotor. Further, in Patent Document 2, key grooves are provided on the outer peripheral surface of the shaft and the inner peripheral surface of the inner rotor, and the shaft and the inner rotor are coupled by inserting the pins so as to abut against both of the key grooves. A "keyway type" rotary pump is disclosed.

JP 2003-269345 A JP 2002-147369 A

In the case of the press-fitting type, once it is press-fitted, it is fixed in that state and there is no room for play. Therefore, the accuracy of perpendicularity at the time of press-fitting is strictly required. In addition, the management for guaranteeing the press-fitting strength so as not to come off is difficult. In addition, there is a problem that disassembly is not possible or reuse becomes impossible when the press-fitting part is removed.
In the case of the keyway type, the keyway is provided only in a part of the circumference, and the entire load is concentrated on the pin that contacts the keyway. Therefore, the load balance is poor, and the pin may be broken when a high torque is applied to the shaft.

Therefore, as another coupling method, the end of the shaft is processed such as “double width cut”, “D cut”, “square cut” to form a fitting shaft portion, while the inner rotor corresponds to these. A “fitting type” coupling method is conceivable in which a shaft hole having a shape is provided and the fitting shaft portion is fitted into the shaft hole.
In the case of the fitting type, the shaft and the inner rotor are fitted symmetrically with the central axis in a well-balanced manner, and can receive a load in a larger area than the contact between the keyway and the pin, and can withstand high torque. Moreover, it is not fixed like the press-fitting type. That is, there is a slight clearance in the fitting portion in the rotational direction, and there is a clearance between the inner rotor end surface and the housing end surface in the axial direction. Because it can move freely within that range, it can absorb variations in the accuracy of parts, right angles during assembly, and parallel accuracy.

By the way, in manufacturing, it is relatively easy to form the fitting shaft portion at the tip of the shaft. However, it is difficult to form the shaft hole in the inner rotor with high accuracy so that there is almost no rattling with the fitting shaft portion. In a normal manufacturing method, the corner of the shaft hole is not finished in an edge shape, and a “corner R” remains. Therefore, if the fitting shaft portion is formed with high accuracy, the fitting shaft portion cannot be assembled by interfering with the corner R of the shaft hole, and if the fitting shaft portion is designed not to interfere with the corner R of the shaft hole, the accuracy of the fitting shaft portion is sufficient. It cannot be secured. As described above, there is a problem that it is impossible to achieve both fitting accuracy and non-interference during assembly.
Further, when a component with insufficient accuracy of the fitting shaft portion is assembled, rattling between the fitting shaft portion and the shaft hole occurs. Therefore, noise and pulsation are generated when the pump is operated, and the durability of the pump is poor.

  The present invention has been made in view of the above-mentioned problems, and can be manufactured with high accuracy and fitability between the fitting shaft portion and the shaft hole, and the fitting shaft portion and the shaft hole have a backlash. An object of the present invention is to provide a rotary pump that has almost no sticking, reduces noise and pulsation during operation, and has excellent durability.

The rotary pump according to claim 1 includes a shaft, an inner rotor, an outer rotor, and a housing.
The shaft includes a fitting shaft portion having a rotation restricting surface and a core keeping surface. The relative rotation of the shaft is restricted by the rotation restricting surface. The core keeping surface is formed adjacent to the rotation restricting surface, and the center axis of the shaft is positioned and held.
External teeth are formed on the outer peripheral side of the inner rotor. The inner rotor has a shaft hole formed by the rotation restricting wall portion and the core retaining wall portion. The rotation restricting wall portion restricts relative rotation of the shaft by contacting the rotation restricting surface. The core retaining wall portion holds the shaft coaxially by fitting the core retaining surface. The inner rotor rotates coaxially with the shaft when the fitting shaft portion is fitted into the shaft hole.
Here, “the rotation regulating surface abuts” is not limited to the meaning that the entire surface is strictly in contact. Actually, there is a clearance equivalent to a “clearance fit” between the rotation restricting wall portion and the rotation restricting surface, and the shaft slightly rotates and contacts one side. Including such a state, it is said that the rotation restricting surface comes into contact.

Inner teeth meshed with the outer teeth are formed on the inner peripheral side of the outer rotor. The outer rotor is arranged eccentrically with the inner rotor.
The housing rotatably accommodates the inner rotor and the outer rotor.
As described above, in the rotary pump, the volume of the gap formed between the external teeth and the internal teeth changes as the inner rotor and the outer rotor rotate, and the fluid is sucked and discharged.

The rotation restricting wall portion of the inner rotor extends to the outside of the core retaining surface from a ridge line between the shaft rotation regulating surface and the core retaining surface. The inner rotor further has a relief wall. The escape wall portion continues from the edge of the rotation restricting wall portion to the core retaining wall portion so as to have a clearance space penetrating in the axial direction between the core retaining surface and the core retaining surface.
Here, “outside the core retaining surface” may be a little outside the core retaining surface. It may be on an extension line of the rotation restricting surface, or may be directed outward from the rotation restricting surface when viewed from the central axis. In any case, it is a requirement not to interfere with the inside of the core retaining surface.

By having the relief wall portion, interference between the fitting shaft portion and the corner R of the shaft hole can be avoided during assembly. Therefore, the fitting accuracy between the fitting shaft portion and the shaft hole can be manufactured with high accuracy and can be assembled.
The relief wall portion extends from the edge of the rotation restricting wall portion corresponding to the ridge line between the rotation restricting surface and the core retaining surface to the outside of the core retaining surface and continues to the core retaining wall portion. That is, the rotation restricting portion is fitted over the entire area between the ridge lines on both sides of the rotation restricting surface. Thereby, the fitting length is ensured to the maximum, and the rattling between the fitting shaft portion and the shaft hole is almost eliminated. Therefore, noise and pulsation during pump operation can be reduced and the durability of the pump can be improved.
Furthermore, since the escape space penetrates in the axial direction of the inner rotor, the hydraulic oil flows through the escape space and is used for lubrication of the shaft bearing portion. Therefore, seizure of the shaft is prevented and the durability of the pump is improved.

In the second to fourth aspects, the shape of the fitting shaft portion of the shaft in the rotary pump according to the first aspect is limited. Furthermore, the names of the fitting shaft part and each part of the shaft hole are defined according to the shape.
The fitting shaft portion according to claim 2 has a shape in which a part of the cylinder is cut by a plane parallel to the central axis, leaving a plane including the diameter. Assuming a single plane, it is a so-called “D-cut” shape.
In this shape, the rotation restricting surface is a flat surface constituting a plane parallel to the central axis. The core retaining surface is a cylindrical surface left by cutting with a flat surface. The rotation restricting wall portion is a flat wall portion into which a flat surface is fitted. The core retaining wall portion is a cylindrical wall portion into which a cylindrical surface is fitted.

  The “D cut” shape is easy to process because it cuts only one surface of the cylinder.

The fitting shaft portion according to claim 3 is a shape in which a part of the cylinder is cut by two planes that are parallel and symmetrical to the central axis, leaving a plane including the diameter. This is a so-called “double width cut” shape, which is a subordinate concept of claim 2.
In this shape, the flat surface is a pair of parallel surfaces that form two planes that are parallel and symmetrical to the central axis. The cylindrical surface is a pair of cylindrical surfaces left by cutting with a pair of parallel surfaces. A flat wall part is a pair of parallel wall part which a pair of parallel surface fits. The cylindrical wall portion is a pair of anti-cylindrical wall portions into which a pair of anti-cylindrical surfaces are fitted.

  The “two-sided width cut” shape cuts two sides of a cylinder in parallel. Compared to the “D-cut” shape, both sides of the cylinder are cut symmetrically, so the load balance is better and higher torque can be withstood. Further, by providing two-plane width accuracy by center distribution, the “pair of parallel surfaces” can have not only a rotation restricting function but also a core retaining function.

The fitting shaft portion according to claim 4 includes two planes in which a part of the cylinder leaves a central axis and is parallel and symmetrical to the central axis, and two other planes orthogonal to the two planes and symmetrical to the central axis. It is a shape cut by a plane. Let's say "Rectangle cut".
In this shape, the rotation restricting surfaces are a pair of first parallel surfaces constituting two planes that are parallel and symmetrical to the central axis. The core retaining surface is a pair of second parallel surfaces constituting another two planes. The rotation restricting wall portion is a pair of first parallel wall portions into which the pair of first parallel surfaces are fitted. The core retaining wall portion is a pair of second parallel wall portions into which the pair of second parallel surfaces are fitted.

  The “square cut” shape is a rectangular cut. By providing both the first parallel surface and the second parallel surface with two-plane width accuracy by center distribution, all surfaces can have both a rotation restricting function and a core retaining function.

In Claims 5-7, the shape of the escape wall part in the rotary pump as described in any one of Claims 1-4 is limited and shown. Here, the boundary between the rotation restricting wall portion and the escape wall portion is referred to as a first continuous portion, and the boundary between the core retaining wall portion and the escape wall portion is referred to as a second continuous portion.
In the relief groove part of claim 5, at least one of the first continuous part and the second continuous part is a straight line having an obtuse angle between which the continuous part is sandwiched.

  When the depression angle sandwiching the continuous portion is an obtuse angle, stress concentration is relatively reduced. Therefore, the durability strength of the inner rotor is improved, and the generation of foreign matter due to edge wear and loss can be prevented.

In the escape groove portion of claim 6, at least one of the first continuous portion and the second continuous portion is a curved surface.
In the relief groove portion of the seventh aspect, the curved surface has a circular arc in a cross section perpendicular to the central axis.

  Since the continuous part is a curved surface, stress concentration hardly occurs. Therefore, the durability strength of the inner rotor is further improved, and the generation of foreign matter due to edge wear and loss can be further prevented.

1 is a block diagram illustrating an overall configuration of a hydraulic fluid supply system for an automatic transmission to which a rotary pump according to a first embodiment of the present invention is applied. It is explanatory drawing explaining the hydraulic circuit in which the rotary pump of 1st Embodiment of this invention is used in the system of FIG. It is sectional drawing of the axial direction which shows the rotary pump of 1st Embodiment of this invention. It is AA sectional drawing of FIG. It is a front view which shows the shaft fitting part of the shaft and inner rotor of the rotary pump of 1st Embodiment of this invention. (A): It is the P section enlarged view of FIG. 5 of the rotary pump of 1st Embodiment of this invention. (B): It is the P section enlarged view of FIG. 5 of the rotary pump of 2nd Embodiment of this invention. (A): It is the P section enlarged view of FIG. 5 of the rotary pump of 3rd Embodiment of this invention. (B): It is the P section enlarged view of FIG. 5 of the rotary pump of 4th Embodiment of this invention. It is an enlarged view which shows the shaft fitting part of the rotary pump of 5th Embodiment of this invention. (A): It is an enlarged view of the shaft fitting part of the rotary pump of 6th Embodiment of this invention. (B): It is an enlarged view of the shaft fitting part of the rotary pump of the modification of 6th Embodiment of this invention. (A): It is an enlarged view corresponding to FIG. 6, FIG. 7 of the rotary pump of a comparative example. (B): It is an enlarged view corresponding to FIG. 6, FIG. 7 of the rotary pump of another comparative example. It is an enlarged view corresponding to FIG. 6, FIG. 7 of the rotary pump of another comparative example.

(First embodiment)
An embodiment of a rotary pump according to the present invention will be described with reference to the drawings. The rotary pump according to the first embodiment of the present invention is applied to an oil pump that supplies hydraulic oil to an automatic transmission.
FIG. 1 shows the overall configuration of a system according to this embodiment.
The engine 80 is a vehicle power generation device, and a crankshaft (not shown) is mechanically connected to a drive shaft 82 that connects the left and right drive wheels 81. The automatic transmission 90 is provided in a power transmission system that transmits power from the crankshaft to the drive wheels 81. The automatic transmission 90 is provided with an electric rotary pump 1.

  The battery 84 is connected to the electric rotary pump 1, the starter 85, the alternator 86, the electrical component 87, and the like. The starter 85 applies initial rotation to the crankshaft of the engine 80. The alternator 86 is mechanically connected to the crankshaft of the engine 80, and converts the transmitted kinetic energy into electric energy. The converted electrical energy is charged in the battery 84. The electrical component 87 includes an air conditioner, a headlight, a fuel injection device, and the like. The ECU 89 is mainly composed of a known microcomputer. The ECU 89 performs so-called idle stop control for automatically stopping the engine 80 when the vehicle is stopped, and automatic start control for automatically starting the engine 80 from the idle stop state. Further, energization control for the rotary pump 1 is performed. In addition, in FIG. 1, illustration was abbreviate | omitted except the control line to the rotary pump 1 in order to avoid becoming complicated.

FIG. 2 shows the configuration of the hydraulic circuit of the automatic transmission 90. The automatic transmission 90 includes an electric rotary pump 1, a mechanical hydraulic pump 91, a control valve 92, a plurality of friction engagement elements including a start clutch 93, a check valve 94, and the like.
The mechanical hydraulic pump 91 is driven by the engine 80, sucks oil stored in the oil pan 98 through the strainer 99, and supplies the oil to a plurality of friction engagement elements via the hydraulic passage 97 and the control valve 92. .

The electric rotary pump 1 is provided in the bypass passage 96 in parallel with the mechanical hydraulic pump 91. The rotary pump 1 has a pump unit 2 and a motor unit 3. The pump unit 2 and the motor unit 3 are connected by a shaft 10. The motor unit 3 is driven and controlled by a driver 4.
In the bypass passage 96, a check valve 94 is provided on the downstream side of the rotary pump 1. Therefore, the hydraulic oil discharged from the mechanical hydraulic pump 91 during the operation of the engine 80 is prevented from flowing back to the rotary pump 1 side. The check valve 94 is opened when the discharge pressure of the rotary pump 1 becomes equal to or higher than the discharge pressure of the mechanical hydraulic pump 91.

With the above configuration, this embodiment is used as follows in idle stop control in which the engine 80 is automatically stopped when the vehicle is stopped.
When the engine 80 stops, the mechanical hydraulic pump 91 driven by the engine 80 stops. When the mechanical hydraulic pump 91 stops, oil cannot be supplied to the friction engagement element. On the other hand, oil is discharged from the friction engagement element, so that the amount of oil is insufficient and the hydraulic pressure is reduced. Thereafter, when the engine 80 is restarted from a state in which the hydraulic pressure of the starting clutch 93 is reduced, a transmission shock is generated.
Therefore, when the engine 80 is stopped, that is, when the mechanical hydraulic pump 91 is stopped, the electric rotary pump 1 is driven to supply oil to the start clutch 93 from the bypass path 96 via the control valve 92, and the start clutch 93 By maintaining the hydraulic pressure, transmission shock during restart can be reduced.

Next, details of the rotary pump 1 will be described with reference to FIGS. 3 is a cross-sectional view taken along the line BB in FIG. 4, and FIG. 4 is a cross-sectional view taken along the line AA in FIG.
The pump unit 2 of the rotary pump 1 is an internal gear type rotary pump, and includes a housing 5, an inner rotor 20, an outer rotor 30, and the like.

The housing 5 includes a first housing 40 and a second housing 50.
The first housing 40 is formed with a suction port 43 and a discharge port 44. The suction port 43 is formed on the front side in FIG. 3 and the discharge port 44 is formed on the back side in FIG.
The end surface 41 of the first housing 40 is formed with a recess 42 for escaping the tip 19 of the shaft 10 and avoiding contact with the first housing 40.

The second housing 50 is formed in a substantially cylindrical shape. A large-diameter portion 51 is formed at an end portion of the second housing 50 in the axial direction on the pump portion 2 side, and a cylindrical tube portion 52 is formed at an end portion on the motor portion 3 side. Inside the large-diameter portion 51, a pump chamber 56 for accommodating the inner rotor 20 and the outer rotor 30 is provided eccentric to the central axis.
A bearing chamber 54 is formed coaxially with the central axis at the end of the cylinder portion 52 on the motor unit 3 side, and an oil seal chamber 53 is formed in the back thereof.

A radial ball bearing 34 is inserted into the bearing chamber 54. The outer ring of the ball bearing 34 is press-fitted into the inner diameter of the bearing chamber 54, and the main body portion 17 of the shaft 10 is press-fitted into the inner ring of the ball bearing 34. As a result, the shaft 10 is supported on the central axis of the cylindrical portion 52 and can rotate.
An oil seal 33 is inserted into the oil seal chamber 53 to seal oil leakage from the pump chamber 56 side to the bearing chamber 54 side.

A bearing hole 55 that penetrates the pump chamber 56 and has an inner diameter slightly larger than the outer diameter of the main body portion 17 of the shaft 10 is formed in the back of the oil seal chamber 53. The bearing hole 55 rotatably supports the shaft 10. As a result, the shaft 10 is supported at the two locations of the ball bearing 34 and the bearing hole 55 and can rotate with almost no runout.
The oil flows into the gap between the inner periphery of the bearing hole 55 and the outer periphery of the main body portion 17 of the shaft 10 via the escape space 29 described later, thereby reducing the sliding resistance of the rotation of the shaft 10. Burn-in is prevented.

  An O-ring groove 57 is formed on the end surface 59 of the second housing 50. The O-ring 37 is fitted into the O-ring groove 57, and the first housing 40 is fastened with the insert nut of the cover 39 and the screw 36 with the second housing 50 interposed therebetween, so that the end surface 41 and the end surface 59 are joined to the outside. The oil leak is sealed.

  An O-ring groove 58 is formed on the outer periphery of the large-diameter portion 51 of the second housing 50, and the O-ring 38 is fitted therein. The large diameter portion 51 is covered with a cover 39 from the motor portion 3 side. The O-ring 38 ensures airtightness between the large diameter portion 51 and the cover 39. The cover 39 accommodates the motor unit 3, and the second housing 50 and the cover 39 constitute a motor unit housing.

The motor unit 3 includes a stator 70, a rotor 60, and the like.
The stator 70 has a magnetic material portion 71 and an insulator 73. The magnetic material portion 71 is formed by laminating thin plates of magnetic material. The insulator 73 formed of a nonmagnetic material is provided outside the magnetic material portion 71 in the axial direction. A winding is wound around the insulator 73. By energizing the winding, a magnetic field is generated in the magnetic material portion 71 of the stator 70.

The rotor 60 is formed in a bottomed cylindrical shape, and is provided rotatably on the radially inner side of the stator 70. The rotor 60 includes a bottom portion 61 and a side wall portion 64 provided on the outer periphery of the bottom portion 61. A hole 62 is formed on the central axis of the bottom 61. Six magnets 65 are affixed in the circumferential direction on the radially outer surface of the side wall 64.
The axial length of the rotor 60 is substantially the same as the axial length of the magnetic material portion 71 of the stator 70. Further, the center in the axial direction of the ball bearing 34 that is the bearing portion and the center in the axial direction of the magnetic material portion 71 are substantially the same. For this reason, the shaft 10 is supported at the approximate center of the magnetic field and efficiently rotates, and the runout is suppressed.
In the accommodation space 68 formed by the inner wall 67 of the rotor 60, the tip of the cylindrical portion 52 of the second housing 50 is accommodated. A gap is provided between the inner wall 67 and the cylindrical portion 52 so as not to contact each other.

  The shaft 10 is substantially cylindrical, the fitting shaft portion 12 that is one end portion in the axial direction is fitted coaxially to the shaft hole 22 of the inner rotor 20, and the rotor press-fit portion 18 that is the other end portion is the rotor. It is press-fitted coaxially into the hole 62 of 60. The fitting shaft portion 12 is provided in a predetermined length range of one end portion of the shaft 10 and is fitted into the shaft hole 22 to restrict relative rotation between the shaft 10 and the inner rotor 20. Thereby, the rotor 60, the shaft 10, and the inner rotor 20 rotate integrally. The details of the shapes of the fitting shaft portion 12 and the shaft hole 22 will be described in detail later.

The inner rotor 20 and the outer rotor 30 are formed of a material having excellent wear resistance such as, for example, iron-based sintered metal, and rotate into a space formed by the pump chamber 56 of the second housing 50 and the first housing 40. Accomodated as possible.
A shaft hole 22 is formed on the central axis of the inner rotor 20. The fitting shaft portion 12 of the shaft 10 is fitted into the shaft hole 22, and the shaft 10 and the inner rotor 20 are rotated together.

Seven outer teeth 21 are formed on the outer periphery of the inner rotor 20.
The outer rotor 30 is housed in the pump chamber 56 with its rotational center being eccentric from the rotational center of the inner rotor 20. Eight inner teeth 31 that mesh with the outer teeth 21 of the inner rotor 20 are formed on the inner periphery of the outer rotor 30. A gap 48 is formed between the outer rotor 30 and the inner rotor 20.
Note that the number of teeth of the inner rotor 20 and the outer rotor 30 is not limited to seven and eight in the present embodiment, and may be appropriately changed according to a required discharge amount and the like. In that case, the number of inner teeth 31 of the outer rotor 30 may be one more than the number of outer teeth 21 of the inner rotor 20.

  A suction-side oil chamber 45 and a discharge-side oil chamber 46 are formed on both sides of the pump chamber 56 across the first housing 40 and the second housing 50. The suction side oil chamber 45 communicates with the suction port 43, and the discharge side oil chamber 46 communicates with the discharge port 44. A part of the gap 48 communicates with the suction-side oil chamber 45 and the other part communicates with the discharge-side oil chamber 46. The position of the gap 48 moves as the inner rotor 20 and the outer rotor 30 rotate.

Here, the operation of the rotary pump 1 will be described.
When the winding wound around the insulator 73 of the stator 70 is energized, a magnetic field is generated in the magnetic material portion 71 of the stator 70. Due to the generated magnetic field, the rotor 60, the shaft 10, and the inner rotor 20 are integrally rotated in the clockwise direction shown in FIG. Further, the outer rotor 30 rotates as the inner rotor 20 rotates. When the inner rotor 20 and the outer rotor 30 rotate, the meshing amount of the outer teeth 21 and the inner teeth 31 changes continuously, and the volume of the gap 48 changes continuously. As a result, oil is sucked into the region where the volume of the gap 48 is increased via the suction side oil chamber 45 and the suction port 43, and the discharge side oil chamber 46 and the discharge port 44 are started from the region where the volume of the gap 48 is decreased. Oil is discharged via

Next, a shaft fitting portion between the shaft 10 and the inner rotor 20 that is a characteristic portion of the present invention will be described.
As shown in FIG. 5, the fitting shaft portion 12 of the shaft 10 is fitted in the shaft hole 22 of the inner rotor 20. In the present embodiment, the fitting shaft portion 12 is “two-sided width cut”. That is, the fitting shaft portion 12 has a shape in which a part of the cylinder is cut by two planes that are parallel and symmetrical to the central axis, leaving a plane including the diameter, and the pair of parallel surfaces 132 and 132 and the pair of It has a cylindrical surface 142,142. The corresponding shaft hole 22 is formed by a pair of parallel wall portions 232 and 232 and a pair of cylindrical wall portions 242 and 242.

  The pair of parallel surfaces 132, 132 are fitted into the pair of parallel wall portions 232, 232 and restrict relative rotation of the shaft 10 with respect to the inner rotor 20. The pair of cylindrical surfaces 142 and 142 are fitted into the pair of cylindrical wall portions 242 and 242 to keep the shaft 10 coaxial with the inner rotor 20. Intersecting lines between the parallel surfaces 132 and 132 and the anti-cylindrical surfaces 142 and 142 form ridge lines 15 at four corners.

Here, in terms of manufacturing, it is relatively easy to form the fitting shaft portion 12 at the tip of the shaft 10. However, on the other hand, when forming the shaft hole 22 in the inner rotor 20, in the hole processing, it is formed in an edge shape so that the “corner R” does not remain in the corner portion, and it is formed in the “pin angle” in the manufacturing industry. In general, not easy.
For example, in cutting, the radius R of the blade always remains, so it is impossible to eliminate the corner R. In electric discharge machining, by making an electrode with a pin angle, it is possible to drill a hole that is very close to the pin angle, but strictly speaking, a discharge gap R remains from the electrode corner. Also, the finished dimensions gradually change due to electrode wear. Moreover, even with wire cutting, it is possible to drill holes that are very close to the pin angle, but the effects of the wire diameter R and the discharge gap remain. Alternatively, when the inner rotor 20 is manufactured by sintering with metal powder, there are finishing limits due to the precision of the molding die and the characteristics in the sintering and shaping processes. Thus, in a general manufacturing method, it is inevitable that some “corner R” remains.

  Therefore, the fitting accuracy between the parallel wall portions 232 and 232 and the parallel surfaces 132 and 132, and the fitting accuracy between the anti-cylindrical wall portions 242 and 242 and the anti-cylindrical surfaces 142 and 142, the accuracy with little backlash, Specifically, when it is set with high accuracy equivalent to “H7-g6” defined in JIS, the ridge line 15 of the fitting shaft portion 12 interferes with the corner R of the shaft hole 22 and cannot be assembled.

Therefore, the rotary pump 1 according to the first embodiment of the present invention further includes a relief wall 25 that continues from the end edge of the parallel wall 232 to the cylindrical wall 242 at the corner of the shaft hole 22 of the inner rotor 20. The relief wall portion 25 forms a relief space 29 penetrating in the axial direction of the inner rotor 20 between the fitting shaft portion 12 and the cylindrical surface 142 of the fitting shaft portion 12. The relief space 29 eliminates the corner R of the shaft hole 22 that interferes with the fitting shaft portion 12.
Therefore, the fitting accuracy between the fitting shaft portion 12 and the shaft hole 22 can be manufactured with high accuracy, and interference between the fitting shaft portion 12 and the corner R can be avoided to enable assembly.

Next, a specific example of the shape of the escape space 29 will be described based on an enlarged view of a P part in FIG. P part represents four corners. The first to fourth embodiments shown in FIGS. 6 and 7 are embodiments in which the fitting shaft portion 12 is “two-sided width cut”. A chain double-dashed line indicates a “corner R” that remains in the corner when the escape wall 25 wall is not provided.
In any of the embodiments, the fitting accuracy between the parallel wall portion 232 and the parallel surface 132, and the anti-cylindrical wall portion 242 and the anti-cylindrical surface 142 is processed with high accuracy equivalent to “H7-g6”. In addition, the pair of parallel surfaces 132 and 132 and the pair of parallel wall portions 232 and 232 can have not only a rotation restricting function but also a core retaining function by providing two-surface width accuracy by center distribution.

  FIG. 6A shows the escape space 29 of the first embodiment. The parallel wall portion 232 is in contact with the entire surface up to the ridge line 15 at the end of the parallel surface 132, that is, the maximum fitting length L. The parallel wall portion 232 further extends from the ridge line 15 to the outside of the cylindrical surface 242. A relief wall 25 is provided at the corner of the paired cylindrical wall 242 at the end of the parallel wall 232 so as to “bite into” the paired cylindrical wall 242. Both corners of the relief wall portion 25 form a corner R shape.

The first continuous portion 26 between the parallel wall portion 232 and the escape wall portion 25 is continuous without an edge. Geometrically speaking, the curvature changes continuously. Further, the depression angle α viewed from the wall side in the first continuous portion 26 is regarded as 180 °.
On the other hand, an edge is formed in the second continuous portion 27 of the anti-cylindrical wall portion 242 and the escape wall portion 25. That is, the curvature changes discontinuously. Further, the depression angle β viewed from the wall side in the second continuous portion 27 is an acute angle of about 70 °.

Thus, in the first embodiment, the fitting shaft portion 12 can be assembled to the shaft hole 22 by forming the escape space 29 at the corner of the shaft hole 22.
Further, the fitting shaft portion 12 is fitted into the shaft hole 22 with a maximum length that can be fitted between the parallel wall portion 232 and the parallel surface 132. The “maximum length that can be fitted between the parallel wall portion 232 and the parallel surface 132” is a distance between the ridge lines 15 at both ends of the parallel surface 132, and is referred to as “maximum fitting length L”.
Thereby, rattling between the fitting shaft portion and the shaft hole is reduced. Therefore, noise and pulsation during pump operation can be reduced. Further, the wear of the shaft 10 and the inner rotor 20 is suppressed, and the durability of the pump is improved.

Further, since the escape space 29 penetrates in the axial direction of the inner rotor 20, the oil on the end surface 41 side of the first housing 40 flows into the bearing hole 55 at the back of the pump chamber 56 via the escape space 29. It is used for lubrication between the outer periphery of the main body portion 17 of the shaft 10 and the inner periphery of the bearing hole 55. Therefore, seizure of the shaft 10 is prevented and the durability of the pump is improved.
In addition, since oil is sealed by the oil seal 33 provided at the tip of the bearing hole 55, oil leakage to the motor unit 3 side is prevented.

  By the way, in 1st Embodiment, the 2nd continuous part 27 is a straight line where the depression angle which pinches | interposes the continuous part is an acute angle, and an edge is made. And since the depression angle is an acute angle, stress concentration occurs. Therefore, the durability strength of the inner rotor 20 is disadvantageous, and it is assumed that foreign matter may be generated due to edge wear and loss.

(Second Embodiment)
FIG. 6B shows the escape space 29 of the second embodiment. The parallel wall portion 232 is in contact with the maximum fitting length L and further extends to the outside of the ridge line 15. The escape wall portion 25 is provided so as to be connected to the cylindrical wall portion 242 in the downward direction in the drawing with respect to the first embodiment.
The 1st continuous part 26 is the same as that of 1st Embodiment.
The second continuous portion 27 is formed with an edge, and is similar to the first embodiment in that the curvature changes discontinuously. However, unlike the first embodiment, the depression angle β viewed from the wall side in the second continuous portion 27 is an obtuse angle of about 150 °.

  In the second embodiment, the second continuous portion 27 is a straight line having an obtuse angle between which the continuous portion is sandwiched, and has an edge. However, since the depression angle is an obtuse angle, the stress concentration is relatively small. Therefore, the durability strength of the inner rotor 20 is improved, and the generation of foreign matter due to edge wear and loss can be prevented. Here, similarly to the second continuous portion 27 of the present embodiment, the depression angle sandwiching the first continuous portion 26 may be a straight line with an obtuse angle.

(Third embodiment)
FIG. 7A shows the escape space 29 of the third embodiment. The parallel wall portion 232 is in contact with the maximum fitting length L and further extends to the outside of the ridge line 15. A relief wall 25 is provided at the corner of the paired cylindrical wall 242 at the end of the parallel wall 232 so as to “bite into” the paired cylindrical wall 242. The relief wall 25 is formed of a curved surface having a circular cross section.
The 1st continuous part 26 is the same as that of 1st Embodiment.
The second continuous portion 27 is formed with a curved surface having a circular cross section, and connects the escape wall portion 25 and the anti-cylindrical wall portion 242. Curvature changes continuously.

(Fourth embodiment)
FIG. 7B shows the escape space 29 of the fourth embodiment. The parallel wall portion 232 is in contact with the maximum fitting length L and further extends to the outside of the ridge line 15. A relief wall portion 25 is provided at the corner of the paired cylindrical wall portion 242 at the end of the edge of the parallel wall portion 232 so as to “bite into” the paired cylindrical wall portion 242 and the parallel wall portion 232. The relief wall 25 is formed of a curved surface having a circular cross section.
The second continuous portion 27 is the same as that in the third embodiment.
The first continuous portion 26 is also formed with a curved surface having a circular cross section, and connects the escape wall portion 25 and the parallel wall portion 232. Curvature changes continuously.

In the third and fourth embodiments, at least one of the first continuous portion 26 or the second continuous portion 27 is a curved surface. Since there is no edge, there is almost no stress concentration. Therefore, the durability strength of the inner rotor 20 is further improved, and the generation of foreign matter due to edge wear and loss can be further prevented.
Furthermore, since the curved surface is an arc, it is generally convenient for manufacturing. For example, in the case of wire cutting, the program is simple. Moreover, a general purpose inspection tool can be used.

(Comparative example)
As described above, in any of the first to fourth embodiments, the parallel wall portion 232 is in contact with the maximum fitting length L. In contrast, an example in which the parallel wall portion 232 does not contact the maximum fitting length L will be described as a comparative example.
In the comparative example shown in FIG. 10A, chamfers 101 are provided at the corners of the fitting shaft portion 12 in order to avoid interference with the corner R102 of the shaft hole 22 and enable assembly. In this case, the non-fitting length is ΔL on one side and 2ΔL on both sides with respect to the maximum fitting length L, which causes the shakiness of the shaft 10.
In the comparative example shown in FIG. 10B, escape holes 103 are provided in the corners of the shaft hole 22 by, for example, cutting. In this case as well, the non-fitting length is ΔL on one side and 2ΔL on both sides with respect to the maximum fitting length L, which causes shakiness of the shaft 10.

  In another comparative example shown in FIG. 11, a gap that is necessary and sufficient to avoid interference with the corner R <b> 102 of the shaft hole 22 is provided around the fitting shaft portion 12. That is, the fitting shaft portion 12 is made slightly smaller than the shaft hole 22. In this case, post-processing is not necessary. However, both the rotation restricting function and the core retaining function are insufficient, and the shakiness of the shaft 10 is further increased.

(Fifth embodiment)
FIG. 8 shows a fifth embodiment in which the fitting shaft 121 is “D cut”.
The fitting shaft portion 121 has a flat surface 131 and a cylindrical surface 141, with a part of the cylinder having a D-shaped cross section that is cut by one plane parallel to the central axis, leaving a plane including the diameter. . The corresponding shaft hole 221 is formed by the flat wall portion 231 and the cylindrical wall portion 241.
The “two-sided width cut” has four corners, whereas the “D-cut” has two corners, and the relief space 29 is the first to fourth embodiments of the “two-sided width cut”. It is provided according to. FIG. 8 illustrates an escape space 29 having the same shape as that of the third embodiment.

(Sixth embodiment)
FIG. 9A shows a sixth embodiment in which the fitting shaft portion 123 is a “rectangular cut”.
The fitting shaft portion 123 is cut at a part of a cylinder by two planes that are parallel and symmetrical to the central axis, and two other planes that are orthogonal to the two planes and symmetrical to the central axis. And has a pair of first parallel surfaces 133 and 133 and a pair of second parallel surfaces 143 and 143. The corresponding shaft hole 223 is formed by a pair of first parallel wall portions 233 and 233 and a pair of second parallel wall portions 243 and 243.
In the “rectangular cut”, there are four corners, and the escape space 29 is provided according to the first to fourth embodiments of the “double width cut”. FIG. 9 illustrates an escape space 29 having the same shape as that of the third embodiment.

(Modification of the sixth embodiment)
FIG. 9B shows a modification of the sixth embodiment. In this modification, the four escape spaces 29 are provided at the corners at the front in the rotational direction or at the rear. In this case, in two pairs of parallel surfaces, both surfaces have both a rotation restricting function and a core retaining function. That is, the first parallel surface 133 and the second parallel surface 143, and the first parallel wall portion 233 and the second parallel wall portion 243 cannot be distinguished. The reference numerals in the figure indicate the parallel surface 133 (143) and the parallel wall portion 233 (243).

In the case of the fifth and sixth embodiments as well as the first embodiment, the fitting shaft portion 12 and the shaft hole 22 can be assembled, there is almost no backlash, noise and vibration during operation are reduced, and the pump There is an effect of improving the durability. In addition, oil flows into the bearing hole 55 side through the escape space 29 and is used for lubrication, thereby preventing the seizure of the shaft 10 and improving the durability of the pump.
Furthermore, when the shape of the relief space 29 is the shape of the second to fourth embodiments, since the stress concentration is small, the durability strength of the inner rotor 20 is improved, and the generation of foreign matters due to edge wear and loss can be prevented. There is an effect.

(Other embodiments)
In the said embodiment, the rotary pump driven by the electric motor was shown. However, the present invention is not limited to an electric pump, and can also be applied to a rotary pump driven by an engine, hydraulic pressure, air pressure, or other energy.
Moreover, in the said embodiment, the rotary pump was an oil pump which pumps oil. However, it may be a pump that pumps fluid other than oil, such as a water pump.
Moreover, in the said embodiment, the electric rotary pump was used for the automatic transmission of the vehicle. However, it is of course possible to apply to rotary pumps in other fields.
As mentioned above, this invention is not limited to the said embodiment at all, In the range which does not deviate from the meaning of invention, it can implement with a various form.

1: rotary pump, 2: pump part, 3: motor part, 4: driver, 5: housing
10: shaft, 12, 121, 123: fitting shaft portion, 13: rotation restricting surface, 131: flat surface, 132: parallel surface, 133: first parallel surface, 14: core retaining surface, 141: cylindrical surface, 142: anti-cylindrical surface, 143: second parallel surface, 15: ridge line, 17: body portion, 18: rotor press-fitting portion, 19: tip portion, 20: inner rotor, 21: external teeth, 22, 221, 223: shaft Hole, 23: rotation regulating wall, 231: flat wall, 232: parallel wall, 233: first parallel wall, 24: core retaining wall, 241: cylindrical wall, 242: anti-cylindrical wall, 243: second parallel wall portion, 25: escape wall portion, 26: first continuous portion, 27: second continuous portion, 29: escape space, 30: outer rotor, 31: internal teeth, 33: oil seal, 34: Ball bearing, 36: screw, 37, 38: O-ring, 39: cover, 40: 1 housing, 41: end face, 42: recess, 43: suction port, 44: discharge port, 45: suction side oil chamber, 46: discharge side oil chamber, 48: gap portion, 50: second housing, 51: large diameter Part, 52: cylinder part, 53: oil seal chamber, 54: bearing chamber, 55: bearing hole, 56: pump chamber, 57, 58: O-ring groove, 59: end face, 60: rotor, 62: hole, 65: Magnet: 70: Stator, 71: Magnetic material part, 73: Insulator, 80: Engine, 81: Drive wheel, 82: Drive shaft, 84: Battery, 85: Starter, 86: Alternator, 87: Electrical component, 89: ECU , 90: automatic transmission, 91: mechanical hydraulic pump, 92: control valve, 93: starting clutch, 94: check valve, 96: bypass passage, 97: hydraulic passage, L: maximum fitting , Α, β: the included angle

Claims (7)

A shaft including a fitting shaft portion that has a rotation restriction surface that restricts relative rotation, and a core-holding surface that is formed adjacent to the rotation restriction surface and that is positioned and held by the center axis;
An outer tooth is formed on the outer peripheral side, the rotation restricting wall portion that abuts the rotation restricting surface and restricts relative rotation of the shaft, and the core retaining surface that fits the core retaining surface to hold the shaft coaxially. And an inner rotor that rotates coaxially with the shaft when the fitting shaft portion is fitted into the shaft hole.
Inner teeth meshed with the outer teeth are formed on the inner peripheral side, and an outer rotor arranged eccentrically with the inner rotor,
A housing that rotatably accommodates the inner rotor and the outer rotor,
When the inner rotor and the outer rotor rotate, the volume of the gap formed between the outer teeth and the inner teeth changes, and the rotary pump sucks and discharges fluid,
The inner rotor is
The end of the rotation restricting wall portion extending outward from the ridge line between the rotation restricting surface and the core retaining surface so as to have an escape space penetrating in the axial direction between the core retaining surface and the core retaining surface. A rotary pump characterized in that it further has an escape wall portion that continues from the edge to the core retaining wall portion. The fitting shaft portion has a shape in which a part of the cylinder is cut by a plane parallel to the central axis, leaving a plane including the diameter.
The rotation restricting surface is a flat surface constituting a plane parallel to the central axis,
The core retaining surface is a cylindrical surface left by cutting with the flat surface,
The rotation restricting wall portion is a flat wall portion into which the flat surface is fitted,
The rotary pump according to claim 1, wherein the core retaining wall portion is a cylindrical wall portion into which the cylindrical surface is fitted. The fitting shaft portion has a shape in which a part of the cylinder is cut by two planes that are parallel and symmetrical to the central axis, leaving a plane including the diameter.
The flat surfaces are a pair of parallel surfaces constituting two planes parallel and symmetrical to the central axis,
The cylindrical surfaces are a pair of cylindrical surfaces left by cutting with the pair of parallel surfaces,
The flat wall portion is a pair of parallel wall portions into which the pair of parallel surfaces are fitted,
The rotary pump according to claim 2, wherein the cylindrical wall portion is a pair of anti-cylindrical wall portions into which the pair of anti-cylindrical surfaces are fitted. The fitting shaft part is cut in two planes that are part of the cylinder, leaving the central axis, parallel and symmetrical to the central axis, and two other planes that are orthogonal to the two planes and symmetrical to the central axis Shape,
The rotation restricting surfaces are a pair of first parallel surfaces constituting two planes parallel and symmetrical to the central axis,
The core retaining surface is a pair of second parallel surfaces constituting the other two planes,
The rotation restricting wall portion is a pair of first parallel wall portions into which the pair of first parallel surfaces are fitted,
The rotary pump according to claim 1, wherein the core retaining wall portion is a pair of second parallel wall portions into which the pair of second parallel surfaces are fitted.   At least one of the first continuous part of the rotation restricting wall part and the escape wall part and the second continuous part of the core retaining wall part and the escape wall part has an obtuse angle between which the continuous part is sandwiched. It is a straight line, The rotary pump as described in any one of Claims 1-4 characterized by the above-mentioned.   At least one of the first continuous part of the rotation restricting wall part and the escape wall part and the second continuous part of the core retaining wall part and the escape wall part is a curved surface. Item 5. The rotary pump according to any one of Items 1 to 4.   The rotary pump according to claim 6, wherein the curved surface has a circular cross section in a direction orthogonal to a central axis.

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