WO2018198801A1

WO2018198801A1 - Rotor for gear pump, and gear pump

Info

Publication number: WO2018198801A1
Application number: PCT/JP2018/015406
Authority: WO
Inventors: 小林　喜幸; 孔二樋口; 裕橋本; 智一池田
Original assignee: 日本電産トーソク株式会社
Priority date: 2017-04-28
Filing date: 2018-04-12
Publication date: 2018-11-01

Abstract

This rotor for a gear pump comprises: an inner rotor that has n teeth (n being an integer greater than or equal to 2) facing outward; and an outer rotor that is a ring shape surrounding the periphery of the inner rotor, is positioned eccentrically with regard to the inner rotor, and has (n+1) teeth facing inward. One member of the inner rotor and the outer rotor comprises a group of tooth bottom sections each having an edge along a first setting curve, and a group of tooth tip sections each having an edge along a second setting curve that is different from the first setting curve, said setting curves being envelopes that are obtained by moving a forming circle along a trochoid curve based on one base circle, said forming circle being smaller than the base circle. The edges of the group of tooth tip sections are positioned between the first setting curve and the other member of the inner rotor and the outer rotor.

Description

Gear pump rotor and gear pump

The present invention relates to a gear pump rotor and a gear pump.

Conventionally, a gear pump has been used as an on-vehicle oil pump. In the gear pump, the design of the inner rotor and the outer rotor is important in order to increase the discharge amount and reduce noise. For example, International Publication No. WO2008 / 111270 discloses a technique for performing deformation in the circumferential direction and deformation in the radial direction on a tooth profile formed by a mathematical curve. Examples of the mathematical curve include a cycloid curve or an envelope of an arc group having a center on a trochoid curve.
International Publication No. WO2008 / 111270

By the way, in the gear pump, it is effective to increase the tooth height of the inner rotor and the outer rotor in order to increase the discharge amount with respect to the pump volume. However, it is easy to reduce the noise and increase the tooth height. is not.

The present invention has been made in view of the above problems, and has an object to reduce noise and the like and easily increase the tooth height in a gear pump rotor.

An exemplary gear pump rotor according to the present invention includes an inner rotor having n teeth (n is an integer of 2 or more) facing outward, and an annular shape surrounding the inner rotor. An outer rotor that is arranged eccentrically and has (n + 1) teeth facing inward. Each member of the inner rotor and the outer rotor has an envelope curve obtained by moving a molding circle smaller than the basic circle along a trochoidal curve based on one basic circle as a setting curve. A tooth bottom portion group having an edge along a first setting curve, and a tooth tip portion group having an edge along a second setting curve different from the first setting curve. An edge of the tooth tip group is located between the other member of the inner rotor and the outer rotor and the first set curve.

According to the present invention, noise and the like can be reduced and the tooth height can be easily increased in the gear pump rotor.

FIG. 1 is a cross-sectional view showing a configuration of a gear pump. FIG. 2 is a view showing the inside of the pump chamber. FIG. 3 is a diagram illustrating a part of the outer teeth of the inner rotor. FIG. 4 is a view showing a part of the inner teeth of the outer rotor. FIG. 5 is a diagram for explaining the derivation of the setting curve. FIG. 6 is a diagram for explaining the derivation of the setting curve. FIG. 7 is an enlarged view of the cell.

In this specification, the upper side of FIG. 1 in the direction of the rotation axis R1 of the motor unit 2 is simply referred to as “upper side”, and the lower side is simply referred to as “lower side”. Note that the vertical direction does not indicate the positional relationship or direction when incorporated in an actual device. A direction parallel to the rotation axis R1 is referred to as an “axial direction”.

FIG. 1 is a cross-sectional view showing a configuration of a gear pump 1 according to an exemplary embodiment of the present invention. The gear pump 1 is an internal gear pump, and sucks and discharges a predetermined fluid. The gear pump 1 is, for example, a vehicle-mounted electric oil pump, and is used for a transmission or the like. In the following description, it is assumed that the fluid transferred by the gear pump 1 is oil. The gear pump 1 may be used other than on-vehicle, and the fluid may be other than oil.

The gear pump 1 includes a motor unit 2 and a pump unit 3. As will be described later, the pump unit 3 sucks and discharges oil by driving the motor unit 2. The motor unit 2 includes a motor housing 21, a rotor 22, a stator 23, a bearing 24, and a shaft 25. The motor housing 21 has a covered cylindrical shape that opens downward. A rotor 22, a stator 23, a bearing 24, and a shaft 25 are accommodated in the motor housing 21. A shaft 25 is fixed to the rotor 22. The shaft 25 is centered on the rotation axis R 1 of the motor unit 2. The shaft 25 is supported by the bearing 24 so as to be rotatable about the rotation axis R1. The bearing 24 is held by a holder 211 provided in the motor housing 21. The stator 23 surrounds the outer side of the rotor 22 in the radial direction around the rotation axis R1. The stator 23 is attached to the inner surface of the motor housing 21.

The pump unit 3 is provided below the motor unit 2. The pump unit 3 includes a pump housing 31 and a gear pump rotor 4. The pump housing 31 includes a pump body 32 and a pump cover 33. The pump body 32 is attached to the lower part of the motor housing 21. A recess 322 is provided on the lower surface of the pump body 32. The recess 322 has a cylindrical shape and is recessed toward the motor unit 2. The pump body 32 is provided with a through hole 321 centered on the rotation axis R1. The through hole 321 opens on the bottom surface of the recess 322, that is, the upper surface in the recess 322. The shaft 25 is inserted into the through hole 321. The pump cover 33 is attached to the lower surface of the pump body 32. The pump cover 33 covers the lower side of the recess 322. A pump chamber 34 is formed by the side and bottom surfaces of the recess 322 and the top surface of the pump cover 33. The pump cover 33 is provided with a suction port 331 and a discharge port 332. That is, a suction port 331 and a discharge port 332 are formed in the pump housing 31. The suction port 331 and the discharge port 332 open to the pump chamber 34.

FIG. 2 is a view showing the inside of the pump chamber 34. FIG. 2 shows the inside of the pump chamber 34 viewed from the upper side in the axial direction to the lower side. In FIG. 2, the X direction and the Y direction perpendicular to the axial direction are indicated by arrows. The X direction and the Y direction are perpendicular to each other. A rotation axis R1 and a later-described axis R2 that are parallel to each other are arranged at the same position in the X direction. That is, the rotation axis R1 and the axis R2 overlap in the Y direction. The rotation axis R1 is disposed on the (+ Y) side with respect to the axis R2. In the following description, each configuration of the gear pump rotor 4 is viewed along the axial direction unless otherwise specified.

The gear pump rotor 4 includes an inner rotor 41 and an outer rotor 46. The inner rotor 41 and the outer rotor 46 are accommodated in the pump chamber 34. The inner rotor 41 is a gear having n teeth 42 facing outward. n is an integer of 2 or more, preferably an odd number. Hereinafter, the teeth 42 of the inner rotor 41 are referred to as “external teeth 42”. The n external teeth 42 are provided on the outer periphery of the inner rotor 41 and are arranged at equal intervals in the circumferential direction around the rotation axis R1. In the example of FIG. 2, the number of external teeth 42 in the inner rotor 41 is seven. The lower end of the shaft 25 is fitted into the center hole of the inner rotor 41 and fixed. Thereby, the inner rotor 41 rotates around the rotation axis R1. The rotation axis R1 is also the central axis of the inner rotor 41. Hereinafter, the radial direction around the rotation axis R1 is referred to as “the radial direction of the inner rotor 41”, and the circumferential direction around the rotation axis R1 is referred to as “the circumferential direction of the inner rotor 41”. Details of the external teeth 42 of the inner rotor 41 will be described later.

The outer rotor 46 has an annular shape centering on the axis R2 parallel to the axial direction, and surrounds the inner rotor 41. The outer rotor 46 is a gear having (n + 1) teeth 47 facing inward. Hereinafter, the teeth 47 of the outer rotor 46 are referred to as “inner teeth 47”. The (n + 1) internal teeth 47 are provided on the inner circumference of the outer rotor 46 and are arranged at equal intervals in the circumferential direction around the axis R2. The inner teeth 47 mesh with the outer teeth 42 of the inner rotor 41. In the example of FIG. 2, the number of inner teeth 47 in the outer rotor 46 is eight.

The outer edge of the outer rotor 46 is a circle centered on the axis R2. The axis R2 is also the central axis of the cylindrical recess 322. The diameter of the outer edge of the outer rotor 46 is slightly smaller than the diameter of the recess 322. Actually, oil is filled between the outer surface of the outer rotor 46 and the side surface of the recess 322. In other words, the outer rotor 46 is supported by the side surface of the recess 322 via the oil while being rotatable about the axis R2.

In driving the gear pump 1 to be described later, the inner teeth 47 and the outer teeth 42 mesh with each other, whereby a rotational driving force (torque) is transmitted from the inner rotor 41 to the outer rotor 46, and the outer rotor 46 rotates about the axis R2. To do. Hereinafter, the axis R2 is referred to as a “rotary axis R2.” As described above, the position of the rotation axis R2 is different from the position of the rotation axis R1 of the inner rotor 41, and the rotation axis R2 is arranged on the (−Y) side with respect to the rotation axis R1. That is, the outer rotor 46 is arranged eccentric to the (−Y) side with respect to the inner rotor 41. In the following description, the radial direction around the rotation axis R2 is referred to as “the radial direction of the outer rotor 46”, and the circumferential direction around the rotation axis R2 is referred to as “the circumferential direction of the outer rotor 46”. Details of the inner teeth 47 of the outer rotor 46 will be described later.

2, a suction groove 341 and a discharge groove 342 are provided on the lower surface of the pump chamber 34, that is, on the upper surface of the pump cover 33. The suction groove 341 and the discharge groove 342 are arcuate spaces. For example, an annular region having a circumference centered on the rotation axis R1 as an inner peripheral edge and a circumference centered on the rotation axis R2 as an outer peripheral edge is divided into a (+ Y) side portion and a (−Y) side The suction groove portion 341 and the discharge groove portion 342 are formed in two regions divided by the part, respectively. The suction groove 341 is disposed on the (−X) side, and the discharge groove 342 is disposed on the (+ X) side. The suction groove 341 is connected to the suction port 331 (see FIG. 1), and the discharge groove 342 is connected to the discharge port 332. Actually, the suction groove portion 341 and the discharge groove portion 342 are also provided on the upper surface of the pump chamber 34, that is, the bottom surface of the recess 322 of the pump body 32.

The suction groove 341 and the discharge groove 342 are filled with oil. Thereby, the sliding torque between the inner rotor 41 and the outer rotor 46 and the upper surface and the lower surface of the pump chamber 34 is reduced. In the following description, in the annular region, the (+ Y) side portion and the (−Y) side portion where the suction groove portion 341 and the discharge groove portion 342 are not provided are respectively referred to as “(+ Y) side groove portion non- “Existing region” and “(−Y) side groove non-existing region”. Each groove non-existing region is a region between the end of the suction groove 341 and the end of the discharge groove 342 that face each other in the circumferential direction.

(+ Y) side external teeth 42 in the inner rotor 41 mesh with (+ Y) side internal teeth 47 in the outer rotor 46. A cell 81 that is an oil filling space is formed between the tooth surface of the inner rotor 41 and the tooth surface of the outer rotor 46. Typically, each cell 81 is formed between two adjacent external teeth 42 of the inner rotor 41 and two adjacent internal teeth 47 of the outer rotor 46. Both sides of each cell 81 in the axial direction are covered with the upper surface and the lower surface of the pump chamber 34. The cell 81 is a space formed by the outer teeth 42, the inner teeth 47 and the wall of the pump chamber 34.

In driving the gear pump 1, the motor unit 2 causes the inner rotor 41 shown in FIG. 2 to rotate, for example, counterclockwise around the rotation axis R1. As a result, the outer rotor 46 rotates counterclockwise about the rotation axis R 2 due to the meshing of the (+ Y) side external teeth 42 and the internal teeth 47. In FIG. 2, the rotation directions of the inner rotor 41 and the outer rotor 46 are indicated by arrows D. At this time, the cell 81 also moves along the rotation direction D. In the region overlapping the suction groove portion 341, the width of the gap between the inner rotor 41 and the outer rotor 46 gradually increases from the vicinity of the (+ Y) side groove portion non-existing region toward the front side in the rotation direction D, and the cell 81 The volume of increases gradually. As a result, the oil in the suction port 331 is sucked into the cell 81 through the suction groove 341. In the (−Y) side groove non-existing region, that is, on the side opposite to the portion where the external teeth 42 and the internal teeth 47 are engaged, the volume of the cell 81 is maximized. In the vicinity of the groove non-existing region on the (−Y) side, the two outer teeth 42 of the inner rotor 41 and the two inner teeth 47 of the outer rotor 46 that form the cell 81 are in contact with each other.

In the region overlapping the discharge groove portion 342, the width of the gap between the inner rotor 41 and the outer rotor 46 gradually decreases from the vicinity of the (−Y) side groove portion non-existing region toward the front side in the rotation direction D. The volume of 81 gradually decreases. Thereby, the oil in the cell 81 is discharged to the discharge port 332 through the discharge groove portion 342. In the non-existing region on the (+ Y) side, that is, in the portion where the external teeth 42 and the internal teeth 47 mesh with each other, the volume of the cell 81 is minimized. As described above, in the gear pump 1, the oil is sucked and discharged by the change in volume of the cell 81 and the oil is fed. In the (+ Y) side groove non-existing region, the tip of the external tooth 42 contacts the tooth bottom of the outer rotor 46 (the tooth bottom 491 in FIG. 4 described later).

FIG. 3 is a view showing a part of the outer teeth 42 of the inner rotor 41, and shows the vicinity of one connecting portion 451 described later. In FIG. 3, the inner rotor 41 is shaded in parallel. The inner rotor 41 includes a tooth tip portion group 43, a tooth bottom portion group 44, and a connection portion group 45. The tooth tip group 43 is a set of n tooth tip portions 431 provided on the n external teeth 42. Each tooth tip portion 431 is a portion located at the tip of the outer tooth 42 in the outer edge portion of the inner rotor 41, that is, the edge portion on the outer rotor 46 side. The tooth tip portion 431 includes a position P1 at which the distance from the rotation axis R1 is maximum at the edge of the external tooth. Hereinafter, the position P1 is referred to as “tip point P1”. In FIG. 3, a line C1 connecting the tooth tip P1 and the rotation axis R1 is indicated by a one-dot chain line. The line C 1 is a center line of the outer teeth 42 of the inner rotor 41.

The tooth bottom part group 44 is a set of n tooth bottom parts 441 provided on the n external teeth 42. Each tooth bottom portion 441 is a portion in the vicinity of the boundary between two adjacent external teeth 42 among the edges of the inner rotor 41. The tooth bottom portion 441 includes a position where the distance from the rotation axis R1 is the smallest at the edge of the external tooth 42. The tooth bottom portion 441 also includes a portion of the edge of the inner rotor 41 that is located at the root of the outer tooth 42. When attention is paid only to the circumferential direction of the inner rotor 41, one tooth bottom portion 441 is arranged between two tooth tip portions 431 adjacent to each other. When attention is paid only to the radial direction of the inner rotor 41, the tooth bottom portion group 44 is arranged closer to the rotation axis R 1 than the tooth tip portion group 43.

The connection part group 45 is a set of 2n connection parts 451 provided on the n external teeth 42. Each connection part 451 is a part located between the tooth tip part 431 and the tooth bottom part 441 in the edge part of the inner rotor 41, and is continuous with both. The connecting portion 451 is disposed between the tooth tip portion 431 and the tooth bottom portion 441 in both the circumferential direction and the radial direction of the inner rotor 41. The connection part 451 can be regarded as an intermediate part. At the edge portion of the inner rotor 41, the tooth tip portion 431, the connection portion 451, the tooth bottom portion 441, and the connection portion 451 are repeatedly arranged in this order along the circumferential direction of the inner rotor 41. Connection portions 451 are arranged on both sides of each tooth tip portion 431 in the circumferential direction of the inner rotor 41.

FIG. 4 is a view showing a part of the inner teeth 47 of the outer rotor 46, and shows the vicinity of one connecting portion 401 described later. In FIG. 4, the outer rotor 46 is shaded in parallel. The outer rotor 46 includes a tooth tip portion group 48, a tooth bottom portion group 49, and a connection portion group 40. The tooth tip group 48 is a set of (n + 1) tooth tip portions 481 provided on the (n + 1) inner teeth 47. Each tooth tip portion 481 is a portion located at the tip of the inner tooth 47 in the inner edge portion of the outer rotor 46, that is, the edge portion on the rotating shaft R 2 side. The tooth tip portion 481 includes a position where the distance from the rotation axis R 2 is minimum at the edge of the internal tooth 47.

The tooth bottom part group 49 is a set of (n + 1) tooth bottom parts 491 provided on (n + 1) inner teeth 47. Each tooth bottom portion 491 is a portion in the vicinity of the boundary between two inner teeth 47 adjacent to each other in the edge portion of the outer rotor 46. The tooth bottom portion 491 includes a position P2 at which the distance from the rotation axis R2 is maximum at the edge of the internal tooth 47. Hereinafter, the position P2 is referred to as “the root point P2”. In FIG. 4, a line C2 connecting the root point P2 and the rotation axis R2 is indicated by a one-dot chain line. The line C2 is a boundary line between two internal teeth 47 adjacent to each other. When attention is paid only to the circumferential direction of the outer rotor 46, one tooth bottom portion 491 is disposed between the two tooth tip portions 481 adjacent to each other. When attention is focused only on the radial direction of the outer rotor 46, the tooth tip group 48 is arranged closer to the rotation axis R 2 than the tooth bottom group 49.

The connection part group 40 is a set of 2 (n + 1) connection parts 401 provided on the (n + 1) internal teeth 47. Each connection part 401 is a part located between the tooth tip part 481 and the tooth bottom part 491 among the edges of the outer rotor 46, and is continuous with both. The connection portion 401 is disposed between the tooth tip portion 481 and the tooth bottom portion 491 in both the circumferential direction and the radial direction of the outer rotor 46. At the edge of the outer rotor 46, the tooth tip portion 481, the connection portion 401, the tooth bottom portion 491 and the connection portion 401 are repeatedly arranged in this order along the circumferential direction of the outer rotor 46. Connection portions 401 are arranged on both sides of each tooth tip portion 481 in the circumferential direction of the outer rotor 46.

Subsequently, details of the tooth profiles of the inner rotor 41 and the outer rotor 46 will be described. The

tooth tip portions

431 and 481 and the

tooth bottom portions

441 and 491 of the inner rotor 41 and the outer rotor 46 have edges along a set curve obtained based on the trochoid curve. Here, the derivation of the setting curve will be described. First, as shown in FIG. 5, a basic circle 91 having a predetermined radius is set. Subsequently, a rolling circle 92 having a radius smaller than that of the basic circle 91 is set, and a predetermined drawing point 921 is set in the rolling circle 92. At this time, the circumference of the base circle 91 is the number of teeth of the circumference of the rolling circle 92, that is, n times for the inner rotor 41 and (n + 1) times for the outer rotor 46. The ratio of the distance from the center of the rolling circle 92 to the drawing point 921 to the radius of the rolling circle 92 is called a dislocation coefficient. Then, when the rolling circle 92 is rolled outside the basic circle 91 so as not to slide on the circumference of the basic circle 91, a locus drawn by the drawing point 921 is obtained as a trochoidal curve (epitrochoidal curve) T. .

When the trochoid curve T is obtained, a forming circle 93 having a radius smaller than that of the basic circle 91 is set as shown in FIG. By moving the molding circle 93 along the trochoid curve T in a state where the center of the molding circle 93 is arranged on the trochoid curve T, an envelope of the molding circle 93 is obtained. The envelope is the set curve L. The setting curve L is an envelope formed on the center side of the basic circle 91, for example. As described above, the setting curve L is obtained by moving the molding circle 93 smaller than the basic circle 91 along the trochoidal curve T based on one basic circle 91. The setting curve L is generated using the number of teeth, the radius of the basic circle 91, the dislocation coefficient, and the radius of the forming circle 93 as parameters. As described above, the

tooth tip portions

431 and 481 and the

tooth bottom portions

441 and 491 have edges along the setting curve based on the trochoid curve. Therefore, the driving of the gear pump 1 reduces noise and torque loss when the tooth tip portion 431 and the tooth bottom portion 441 of the inner rotor 41 come into contact with the tooth tip portion 481 and the tooth bottom portion 491 of the outer rotor 46. .

In FIG. 3, the setting curve of the tooth tip part 431 and the setting curve of the tooth bottom part 441 in the inner rotor 41 are indicated by broken lines with reference numerals L3 and L4. Further, a solid line indicates a portion indicating the edge of the tooth tip portion 431 in the setting curve L3 and a portion indicating the edge of the tooth bottom portion 441 in the setting curve L4. The center of the base circle with respect to the setting curve L3 of the tooth tip portion 431 and the center of the base circle with respect to the setting curve L4 of the tooth bottom portion 441 coincide with the rotation axis R1. The setting curve L3 can be regarded as a tip side trochoid curve, and the setting curve L4 can be regarded as a root side trochoid curve.

The radius of the base circle, the dislocation coefficient, and the radius of the forming circle can be determined independently of each other between the setting curve L3 of the tooth tip portion 431 and the setting curve L4 of the tooth bottom portion 441. In the present embodiment, the values of the parameters are different from each other. Therefore, as shown in FIG. 3, the setting curve L3 and the setting curve L4 are different. Some parameter values may be the same between the setting curves L3 and L4.

The setting curve L3 of the tooth tip portion 431 is positioned on the radially outer side of the inner rotor 41 with respect to the setting curve L4 of the tooth bottom portion 441. In the inner rotor 41, the position P 1 where the distance from the rotation axis R 1 is maximum in the setting curve L 3, that is, the portion including the tooth tip point P 1 is the edge of the tooth tip portion 431. The edge of the tooth tip portion 431 is located between the outer rotor 46 surrounding the radially outer side of the inner rotor 41 and the setting curve L4 of the tooth bottom portion 441.

The setting curve L4 of the tooth bottom portion 441 is located on the radially inner side of the inner rotor 41 with respect to the setting curve L3 of the tooth tip portion 431, and a portion including the position where the distance from the rotation axis R1 is minimum in the setting curve L4. It becomes the edge of the tooth bottom part 441. The edge of the tooth bottom portion 441 is located between the rotation axis R1 and the setting curve L3 of the tooth tip portion 431. For example, by making the radius of the base circle for the setting curve L3 larger than the radius of the base circle for the setting curve L4, or by making the radius of the forming circle for the setting curve L3 smaller than the radius of the forming circle for the setting curve L4, etc. The setting curves L3 and L4 as described above can be easily obtained.

In the external tooth 42 having the tooth tip portion 431 and the tooth bottom portion 441, it is possible to increase the tooth height as compared with the case where the shape of the external tooth is determined using a single setting curve. The tooth height of the external teeth 42 is, for example, the distance between the position where the distance from the rotation axis R1 is maximum at the edge of the tooth tip 431 and the rotation axis R1, and the distance from the rotation axis R1 at the edge of the tooth bottom 441. It is obtained as the difference between the position where the distance is minimum and the distance between the rotation axis R1. The setting curves L3 and L4 can be regarded as two curves shifted by a distance indicated by an arrow K1 in FIG. 3 according to a required tooth height.

In the inner rotor 41, the edge of the tooth tip portion 431 and the edge of the tooth bottom portion 441 are connected by the edge of the connection portion 451. Each connection portion 451 includes a plurality of curved portions. Specifically, the connection portion 451 includes a first clothoid curve portion 453 and a second clothoid curve portion 454. The first clothoid curve portion 453 has an edge along the first clothoid curve V11. The second clothoid curve portion 454 has an edge along a second clothoid curve V12 that is different from the first clothoid curve V11. In FIG. 3, a part of the first clothoid curve V11 indicating the edge of the first clothoid curve part 453 and a part of the second clothoid curve V12 indicating the edge of the second clothoid curve part 454 are indicated by thick solid lines. Yes.

The first clothoid curve portion 453 is disposed between the tooth tip portion 431 and the second clothoid curve portion 454 and is continuous with both. The 2nd clothoid curve part 454 is arrange | positioned between the 1st clothoid curve part 453 and the tooth root part 441, and continues to both. In FIG. 3, a reference point U11 is given to a boundary point between the edge of the tooth tip portion 431 and the edge of the first clothoid curve portion 453, and the boundary between the edge of the first clothoid curve portion 453 and the edge of the second clothoid curve portion 454 is provided. A point U12 is attached to the point, and a point U13 is attached to a boundary point between the edge of the second clothoid curve portion 454 and the edge of the tooth bottom portion 441.

The tangent of the edge of the tooth tip portion 431 at the boundary point U11 is the same as the tangent of the edge of the first clothoid curve portion 453 at the boundary point U11. Therefore, the edge of the tooth tip portion 431 and the edge of the first clothoid curve portion 453 are smoothly connected. That is, the edge of the tooth tip portion 431 and the edge of the connection portion 451 are smoothly connected. For example, when a slight deviation in the position and inclination of two curves at a boundary point is included within an allowable error at the time of manufacturing the inner rotor 41, the two tangents of the two curves at the boundary point are the same. Can be considered.

Similarly, the tangent of the edge of the second clothoid curve portion 454 at the boundary point U13 is the same as the tangent of the edge of the tooth bottom portion 441 at the boundary point U13. Therefore, the edge of the second clothoid curve portion 454 and the edge of the root portion 441 are smoothly connected. That is, the edge of the connection part 451 and the edge of the tooth bottom part 441 are smoothly connected. The tangent of the edge of the first clothoid curve portion 453 at the boundary point U12 is the same as the tangent of the edge of the second clothoid curve portion 454 at the boundary point U12. Therefore, the edge of the 1st clothoid curve part 453 and the edge of the 2nd clothoid curve part 454 are connected smoothly. In this way, the edges of the plurality of curved portions included in the connection portion 451 are also smoothly connected.

The second clothoid curve portion 454 includes a portion indicating the inflection point M1 of the second clothoid curve V12. Here, the radial direction of the inner rotor 41 along the center line C1 is the x axis, and the direction perpendicular to the center line C1 (the length direction in the circumferential direction of the inner rotor 41) is the y axis, and the second clothoid curve V12 is represented by y = F (x). In this case, the inflection point M1 is a position where the value of f ″ (x), which is the second derivative of f (x), is switched. At the inflection point M1, the curvature of the second clothoid curve V12 is 0. In the following description, “curvature” means the magnitude (absolute value) of curvature. In the example of FIG. 3, the value at the inflection point M1 of f ′ (x), which is a single derivative of f (x), is zero. That is, the inclination of the second clothoid curve V12 coincides with the inclination of the center line C1 at the inflection point M1.

Since the clothoid curve is a line whose curvature changes in proportion to the curve length, the curvature of the edge of the second clothoid curve portion 454 gradually increases from the portion showing the inflection point M1 toward the tooth bottom portion 441. Further, the curvature of the edge of the second clothoid curve portion 454 gradually increases from the portion indicating the inflection point M1 toward the first clothoid curve portion 453. The curvature of the edge of the first clothoid curve portion 453 gradually decreases as it moves away from the second clothoid curve portion 454, that is, approaches the tooth tip portion 431. The edge of the first clothoid curve portion 453 does not include an inflection point. In the tooth tip portion 431 of FIG. 3, the curvature is minimum at the tooth tip point P1. The two connection portions 451 disposed on both sides of the tooth tip portion 431 in the circumferential direction of the inner rotor 41 are symmetrical with respect to the center line C1. When the edge of the 1st clothoid curve part 453 and the edge of the 2nd clothoid curve part 454 have the said shape, the whole external tooth 42 becomes a smooth shape.

In FIG. 4, the setting curve of the tooth tip portion 481 and the setting curve of the tooth bottom portion 491 in the outer rotor 46 are indicated by broken lines with symbols L8 and L9. Further, a solid line indicates a portion indicating the edge of the tooth tip portion 481 in the setting curve L8 and a portion indicating the edge of the tooth bottom portion 491 in the setting curve L9. The center of the base circle with respect to the setting curve L8 of the tooth tip portion 481 and the center of the base circle with respect to the setting curve L9 of the tooth bottom portion 491 both coincide with the rotation axis R2. The setting curve L8 can be regarded as a tip side trochoid curve, and the setting curve L9 can be regarded as a root side trochoid curve. For example, the setting curve L8 of the tooth tip portion 481 in the outer rotor 46 is acquired using the parameter values in the setting curve L4 of the tooth bottom portion 441 of the inner rotor 41. Similarly, the setting curve L9 of the tooth bottom portion 491 in the outer rotor 46 is acquired using the parameter values in the setting curve L3 of the tooth tip portion 431 of the inner rotor 41. Depending on the clearance set between the external teeth 42 and the internal teeth 47, the value of the parameter may be appropriately corrected.

As shown in FIG. 4, also in the outer rotor 46, the setting curve L8 of the tooth tip portion 481 and the setting curve L9 of the tooth bottom portion 491 are different. Specifically, the setting curve L9 of the tooth bottom portion 491 is located on the radially outer side of the outer rotor 46 than the setting curve L8 of the tooth tip portion 481. In the outer rotor 46, the position P 2 at which the distance from the rotation axis R 2 is maximum in the setting curve L 9, that is, the portion including the root point P 2 is the edge of the root portion 491. The edge of the tooth bottom portion 491 is located between the set curve L8 of the tooth tip portion 481 and the outer edge of the outer rotor 46. The setting curve L8 of the tooth tip portion 481 is located on the radially inner side of the outer rotor 46 with respect to the setting curve L9 of the tooth bottom portion 491, and includes a portion of the setting curve L8 where the distance from the rotation axis R2 is minimum. Becomes the edge of the tooth tip 481. The edge of the tooth tip portion 481 is located between the inner rotor 41 and the setting curve L9 of the tooth bottom portion 491.

In the internal tooth 47 having the tooth tip portion 481 and the tooth bottom portion 491, it is possible to increase the tooth height as compared with the case where the shape of the internal tooth is determined using a single setting curve. The tooth height of the internal teeth 47 is, for example, the distance between the rotation axis R2 and the position where the distance from the rotation axis R2 is maximum at the edge of the root portion 491, and It is obtained as the difference between the position where the distance is minimum and the distance between the rotation axis R2. The setting curves L8 and L9 can also be regarded as two curves shifted by a distance indicated by an arrow K2 in FIG. 4 according to the required tooth height.

In the outer rotor 46, the edge of the tooth tip portion 481 and the edge of the tooth bottom portion 491 are connected by the edge of the connection portion 401. Connection portion 401 includes a plurality of curved portions. Specifically, the connection portion 401 includes a first clothoid curve portion 403 and a second clothoid curve portion 404. The first clothoid curve portion 403 has an edge along the first clothoid curve V21. The second clothoid curve portion 404 has an edge along a second clothoid curve V22 that is different from the first clothoid curve V21. In FIG. 4, a part of the first clothoid curve V21 showing the edge of the first clothoid curve part 403 and a part of the second clothoid curve V22 showing the edge of the second clothoid curve part 404 are shown by thick solid lines. Yes.

The first clothoid curve portion 403 is disposed between the tooth tip portion 481 and the second clothoid curve portion 404 and is continuous with both. The 2nd clothoid curve part 404 is arrange | positioned between the 1st clothoid curve part 403 and the tooth root part 491, and continues to both. In FIG. 4, the reference point U 21 is given to the boundary point between the edge of the tooth tip portion 481 and the edge of the first clothoid curve portion 403, and the boundary between the edge of the first clothoid curve portion 403 and the edge of the second clothoid curve portion 404 is added. A point U22 is attached to the point, and a point U23 is attached to a boundary point between the edge of the second clothoid curve portion 404 and the edge of the tooth bottom portion 491.

The tangent of the edge of the tooth tip part 481 at the boundary point U21 is the same as the tangent of the edge of the first clothoid curve part 403 at the boundary point U21, and the edge of the tooth tip part 481 and the edge of the first clothoid curve part 403 Is connected smoothly. Similarly, the tangent of the edge of the second clothoid curve portion 404 at the boundary point U23 is the same as the tangent of the edge of the tooth bottom portion 491 at the boundary point U23, and the edge of the second clothoid curve portion 404 and the edge of the tooth bottom portion 491 are the same. And are connected smoothly. Further, the tangent of the edge of the first clothoid curve portion 403 at the boundary point U22 is the same as the tangent of the edge of the second clothoid curve portion 404 at the boundary point U22, and the edge of the first clothoid curve portion 403 and the second clothoid The edge of the curved portion 404 is smoothly connected. The first clothoid curve portion 403 includes a portion indicating the inflection point M2 of the first clothoid curve V21. At the inflection point M2, the curvature of the first clothoid curve V21 is zero. In addition, the slope of the first clothoid curve V21 coincides with the slope of the boundary line C2 at the inflection point M2.

The curvature of the edge of the first clothoid curve portion 403 gradually increases from the portion indicating the inflection point M2 toward the tooth tip portion 481. Further, the curvature of the edge of the first clothoid curve portion 403 gradually increases from the portion indicating the inflection point M2 toward the second clothoid curve portion 404. The curvature of the edge of the second clothoid curve portion 404 gradually decreases as it moves away from the first clothoid curve portion 403, that is, approaches the tooth bottom portion 491. The edge of the second clothoid curve portion 404 does not include an inflection point. In the root portion 491 of FIG. 4, the curvature is minimum at the root point P2. The two connecting portions 401 disposed on both sides of the tooth bottom portion 491 in the circumferential direction of the outer rotor 46 are symmetrical with respect to the boundary line C2. Since the edge of the first clothoid curve portion 403 and the edge of the second clothoid curve portion 404 have the above-described shape, the entire inner teeth 47 have a smooth shape.

In the gear pump 1, the part from the vicinity of the boundary point U 13 to the vicinity of the boundary point U 12 at the edge of the outer tooth 42 contacts the part from the vicinity of the boundary point U 21 to the vicinity of the boundary point U 22 at the edge of the inner tooth 47. Torque is transmitted to the outer rotor 46. The portion of the edge of the outer tooth 42 is a meshing portion with the inner tooth 47, and is along the radial direction of the inner rotor 41. The portion of the edge of the inner tooth 47 is a meshing portion with the outer tooth 42, and is along the radial direction of the outer rotor 46. Accordingly, the torque of the inner rotor 41 can be efficiently transmitted to the outer rotor 46. The edges of the external teeth 42 are smoothly continuous at the boundary points U12 and U13, and the edges of the internal teeth 47 are smoothly continuous at the boundary points U21 and U22. As a result, noise generated by contact between the above-described portion of the edge of the outer tooth 42 and the above-described portion of the edge of the inner tooth 47 is reduced, and the outer rotor 46 rotates smoothly. In the inner rotor 41, the boundary point U 11 between the connection portion 451 and the tooth tip portion 431 is located on the outer side in the radial direction of the inner rotor 41 than the meshing portion of the outer teeth 42. Further, the boundary point U 23 between the connection portion 401 and the tooth bottom portion 491 in the outer rotor 46 is located on the radially outer side of the outer rotor 46 with respect to the meshing portion of the inner teeth 47.

FIG. 7 is an enlarged view of the cell 81 when the volume is maximized. FIG. 7 shows the cell 81 in a state where the groove is not present on the (−Y) side, that is, the most (−Y) side cell 81 in FIG. As shown in FIG. 7, when the volume of the cell 81 is maximized, the two external teeth 42 adjacent to each other in the inner rotor 41 come into contact with the two internal teeth 47 adjacent to each other in the outer rotor 46. In FIG. 7, a contact point between the external tooth 42 and the internal tooth 47 is denoted by reference numeral H 1. For example, the two contact points H1 are arranged at the same position in the Y direction.

In the two external teeth 42, two connecting portions 451 (see FIG. 3) face each other in the X direction via the cell 81, and the inflection points M1 of the two connecting portions 451 are arranged at the same position in the Y direction. Is done. In the two internal teeth 47, two connecting portions 401 (see FIG. 4) face each other in the X direction via the cell 81, and the inflection point M2 of the two connecting portions 401 is the same position in the Y direction. Placed in. In FIG. 7, the shortest distance between two inflection points M1 that face each other via the cell 81 is indicated by an arrow X1, and the shortest distance between two inflection points M2 is indicated by an arrow X2. The distance X 1 is the width of the gap between the adjacent external teeth 42 in the inner rotor 41. The distance X 2 is the width of the gap between the inner teeth 47 adjacent to each other in the outer rotor 46. The width X1 of the gap between the external teeth 42 is larger than the width X2 of the gap between the internal teeth 47. That is, (X1> X2) is satisfied. Depending on the design of the gear pump rotor 4, (X1 ≦ X2) may be satisfied. In the example of FIG. 7, the shortest distance X3 between the two contact points H1 that face each other via the cell 81 is larger than the widths X1 and X2 of the gaps between the teeth.

As described above, at the edge of the inner tooth 47 of the outer rotor 46, the position where the distance from the rotation axis R2 is maximum is the root point P2. At the edge of the outer teeth 42 of the inner rotor 41, the position where the distance from the rotation axis R1 is the minimum is the root point P3. The rotation axis R2 is disposed on the (−Y) side with respect to the rotation axis R1. When the volume of the cell 81 is maximized, the root points P2, P3 are arranged at the same position in the X direction, and the distance between the root points P2, P3 in the radial direction of the inner rotor 41 is maximized. In FIG. 7, the shortest distance between the root points P2 and P3 facing each other via the cell 81 is indicated by an arrow Y1. The distance Y1 is the maximum length of the cell 81 in the radial direction. In the gear pump 1, the outer teeth 42 and the inner teeth 47 are large, so that the maximum length Y1 of the cell 81 and the volume of the cell 81 are also increased. The maximum length Y1 of the cell 81 is larger than any of the widths X1 and X2 of the gap between the teeth. That is, (Y1> X1 and Y1> X2) are satisfied. In the example of FIG. 7, the maximum length Y1 of the cell 81 is smaller than the distance X3 between the contact points H1.

As described above, in the gear pump rotor 4, the inner rotor 41 includes the tooth bottom portion group 44 having an edge along the setting curve L4 and the edge along the setting curve L3 that is different from the setting curve L4. And the tooth tip group 43. The edge of the tooth tip group 43 is located between the outer rotor 46 and the set curve L4. Thereby, the height of the outer teeth 42 of the inner rotor 41, that is, the tooth height can be easily increased. As a result, the volume of the cell 81 can be increased, and the discharge amount with respect to the pump volume in the gear pump 1 can be increased. Further, since the setting curves L3 and L4 are based on the trochoid curve, noise and the like in the gear pump rotor 4 can be reduced.

Similarly, the outer rotor 46 includes a tooth root group 49 having an edge along the setting curve L9 and a tooth tip group 48 having an edge along a setting curve L8 different from the setting curve L9. . The edge of the tooth tip group 48 is located between the inner rotor 41 and the setting curve L9. Thereby, while reducing a noise etc., the tooth height of the outer rotor 46 can be enlarged easily. By increasing the tooth heights of both the inner rotor 41 and the outer rotor 46, the discharge amount in the gear pump 1 can be further increased. In other words, the area of the outer rotor 46 perpendicular to the axial direction can be reduced without changing the theoretical discharge amount. Thereby, the area of the gear pump 1 perpendicular to the axial direction can be reduced, loss torque can be reduced, and power consumption can be suppressed.

In the gear pump rotor 4, when the volume of the cell 81 is maximized, the maximum length Y1 of the cell 81 in the radial direction of the inner rotor 41 is the width X1 of the gap between the adjacent external teeth 42 in the inner rotor 41. , And the width X2 of the gap between the inner teeth 47 adjacent to each other in the outer rotor 46 is larger. Also from this point of view, the gear pump 1 realizes an increase in the discharge amount.

Each of the inner rotor 41 and the outer rotor 46 further includes a connection portion group provided between the tooth bottom portion group and the tooth tip portion group, and the edge of the connection portion group includes the edge of the tooth bottom portion group and the tooth tip portion group. Connect the edges of the door smoothly. Thereby, the noise and pulsation in the gear pump 1 can be suppressed. In addition, since each of the connecting portion groups includes a clothoid curve portion having an edge along one clothoid curve, the outer shape of the teeth can be easily made smooth. When the clothoid curve portion includes a portion indicating the inflection point of the one clothoid curve, the direction of the curvature, that is, the sign of the curvature can be switched smoothly. Each of the connecting portion groups further includes another clothoid curve portion having an edge along the other clothoid curve, so that the external shape of the tooth can be more easily and smoothly formed.

In the gear pump rotor 4, the edge of the clothoid curve portion and the edge of the other clothoid curve portion are continuous, and the curvature of the edge of the clothoid curve portion is changed from the portion indicating the inflection point to the other clothoid curve portion. Gradually increases toward. Moreover, the curvature of the edge of the other clothoid curve portion gradually decreases as the distance from the clothoid curve portion increases. Thereby, it is possible to easily and smoothly connect the respective edges of the connection portion group and the edges of the tooth tip portion or the tooth bottom portion.

The gear pump rotor 4 and the gear pump 1 can be variously modified.

In the gear pump rotor 4, only one member of the inner rotor 41 and the outer rotor 46 includes a root group having an edge along the first setting curve, and an edge along a second setting curve different from the first setting curve. And a group of tooth tips. Also in this case, since the edge of the tooth tip group is located between the other member of the inner rotor 41 and the outer rotor 46 and the first set curve, the tooth height of the one member is easily increased. be able to. The tooth profile of the other member is determined by another method. Moreover, it is preferable that the said one member further contains the connection part group provided between a tooth root part group and a tooth tip part group.

In the preferred gear pump rotor 4, as in the above-described embodiment, the other member has another tooth bottom group having an edge along the third setting curve and a fourth setting curve different from the third setting curve. Another tooth tip group having an edge, and the edge of the other tooth tip group is located between the one member and the third setting curve. Thereby, the tooth height in both the inner rotor 41 and the outer rotor 46 can be easily increased, and the discharge amount in the gear pump 1 can be more reliably increased.

Each connecting

portion

451, 401 may include three or more clothoid curve portions, or may be constituted by one clothoid curve portion. In the

connection parts

451 and 401, by using a clothoid curve, it is possible to easily connect the edge of the tooth tip part and the edge of the tooth bottom part smoothly. Thereby, the noise and pulsation in the gear pump 1 can be suppressed. Since reduction of hydraulic pulsation is important in an in-vehicle electric oil pump, the gear pump 1 can be said to be particularly suitable for an in-vehicle electric oil pump. The shape of the edge of the clothoid curve portion may be appropriately changed according to the shapes of the tooth bottom portion and the tooth tip portion. In the gear pump rotor 4, a type of curve other than the clothoid curve may be used at one or both of the inner rotor 41 and the outer rotor 46.

Depending on the design of the gear pump rotor 4, when the volume of the cell 81 is maximized, the maximum length Y1 of the cell 81 in the radial direction of the inner rotor 41 is the width X1 of the gap between the external teeth 42 and the inner It may be smaller than one or both of the widths X 2 of the gaps between the teeth 47.

The configurations in the above embodiment and each modification may be combined as appropriate as long as they do not contradict each other.

This application claims priority based on 62 / 491,405, which is a US patent application filed on April 28, 2017, and incorporates all the descriptions described in the US patent application.

This application claims priority based on Japanese Patent Application No. 2017-154252, which was filed on August 9, 2017, and uses all the contents described in the Japanese Patent Application.

The gear pump rotor and gear pump according to the present invention can be used in various applications.

DESCRIPTION OF SYMBOLS 1 Gear pump 2 Motor part 4 Gear pump rotor 31

Pump housing

40,45 Connection part group 41 Inner rotor 42

External tooth

43,48 Tooth tip part group 44,49 Tooth bottom part group 46 Outer rotor 47 Inner tooth 81 Cell 91 Base circle 93 Molding circle 331 Suction port 332

Discharge port

403, 404, 453, 454 Clothoid curve part L, L3, L4, L8, L9 Setting curve M1, M2 Inflection point T Trochoid curve V11, V12, V21, V22 Clothoid curve X1, X2 Width of gap between teeth Y1 Maximum length of cell

Claims

An inner rotor having n teeth (n is an integer of 2 or more) facing outward,
An outer rotor having an annular shape surrounding the inner rotor, arranged eccentrically with respect to the inner rotor, and having (n + 1) teeth facing inward;
With
One member of the inner rotor and the outer rotor is
A set of envelops obtained by moving a molding circle smaller than the basic circle along a trochoidal curve based on one basic circle, and a set of roots each having an edge along the first setting curve; ,
Each tooth tip group having an edge along a second setting curve different from the first setting curve;
With
The gear pump rotor, wherein an edge of the tooth tip group is located between the other member of the inner rotor and the outer rotor and the first set curve.
The other member is
Other root groups each having an edge along the third set curve;
Each of the other tip group having an edge along a fourth setting curve different from the third setting curve;
With
The gear pump rotor according to claim 1, wherein an edge of the other tooth tip group is located between the one member and the third setting curve.
The one member further includes a connection part group provided between the tooth bottom part group and the tooth tip part group,
The gear pump rotor according to claim 1 or 2, wherein an edge of the connection portion group smoothly connects an edge of the tooth bottom portion group and an edge of the tooth tip portion group.
The gear pump rotor according to claim 3, wherein each of the connection portion groups includes a clothoid curve portion having an edge along one clothoid curve.
Each of the connection groups further includes another clothoid curve portion having an edge along another clothoid curve,
The gear pump rotor according to claim 4, wherein the clothoid curve portion includes a portion indicating an inflection point of the one clothoid curve.
The edge of the clothoid curve portion and the edge of the other clothoid curve portion are continuous,
The curvature of the edge of the clothoid curve portion gradually increases from the portion showing the inflection point toward the other clothoid curve portion,
The gear pump rotor according to claim 5, wherein the curvature of the edge of the other clothoid curve portion gradually decreases as the distance from the clothoid curve portion increases.
When the space formed between the two adjacent teeth of the inner rotor and the two adjacent teeth of the outer rotor is a cell, when the volume of the cell is maximized, the diameter of the inner rotor The maximum length of the cell in the direction is larger than any of a width of a gap between adjacent teeth in the inner rotor and a width of a gap between adjacent teeth in the outer rotor. The rotor for gear pumps as described in any one of these.
The gear pump rotor according to any one of claims 1 to 7, wherein a width of a gap between adjacent teeth in the inner rotor is larger than a width of a gap between adjacent teeth in the outer rotor.
A gear pump rotor according to any one of claims 1 to 8,
A motor unit for rotating the inner rotor of the gear pump rotor;
A pump housing formed with a suction port and a discharge port;
A gear pump comprising:
10. The gear pump according to claim 9, which feeds oil.