JP2003176790A - Fluid pump - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the increase of wear and internal leakage by drawing each gear to one side and inclining each gear in a gear type fluid pump. <P>SOLUTION: A drive gear 30 of an external gear and a driven gear 31 of an internal gear are arranged in a gear chamber formed in a housing H so that each both side surfaces rotatably slide with both inside surfaces of the gear chamber. Operating oil sucked from a suction passage 21 is delivered from a delivery passage 26. A spiral groove 31a for reducing a sliding resistance between the side surface of the driven gear and the inside surface of the gear chamber is formed between the outer circumference of the driven gear and the inner circumference of the gear chamber rotatably sliding with outer circumference of the driven gear. The spiral groove makes the operating oil disposed between the driven gear and the inside surface of the gear chamber which is a side where the driven gear is separated move between the driven gear and the inside surface of the gear chamber which is a side where the driven gear is pressed. A similar spiral groove 30b may be formed between the inner circumference of the drive gear and the outer circumference of a supporting member for supporting the driven gear. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil pump for supplying hydraulic oil to an automatic transmission of an automobile.

[0002]

2. Description of the Related Art In an oil pump of this type, as shown in FIGS. 10 and 11, a drive gear 30 and a driven gear 31 having internal teeth meshing with the drive gear 30 are formed in a circular housing recess 2 formed in a pump body 1. It is housed and covered with the pump cover 3 in a liquid-tight manner, and on each inner surface of the pump body 1 and the pump cover 3, at a position corresponding to the suction region where the volume between the teeth of the gears 30 and 31 meshing with each other gradually increases. The pair of suction side concave grooves 4a and 4b are opened, and both gears 30 and 31 are opened.
There is a pair of discharge side concave grooves 6a and 6b opened at positions corresponding to the discharge region where the volume between the teeth of the teeth gradually decreases. In the illustrated example, the suction-side concave grooves 4a and 4b are both suction ports communicating with the suction passage 5, and the discharge-side concave groove 6a on the pump body 1 side is a discharge port communicating with the discharge passage 7. The discharge side concave groove 6b on the pump cover 3 side is
In order to avoid the fluid passage formed in the pump cover 3,
It is a shallow groove that does not communicate with the discharge passage 7. The drive gear 30 is supported on the tip of the input shaft 8 supported in the center hole of the pump body 1 via the bearing bush 9, and a pair of keys 30 a protruding from the inner surface of the drive gear 30 is attached to the tip of the input shaft 8. The key groove 8a formed in the above is engaged to rotate and drive.

[0003]

In such an oil pump, the shape and area of the openings of the suction side concave grooves 4a and 4b formed on the inner surfaces of the pump body 1 and the pump cover 3 are the same, and The shapes and areas of the openings of the discharge side concave grooves 6a and 6b are the same, and the gears 3 are
Each suction side recessed groove 4 arranged on both sides of 0 and 31 to face each other.
The thrust force that pushes each gear 30, 31 in one axial direction by balancing the forces applied to each gear 30, 31 by the pressure of the hydraulic oil in the a, 4b and the discharge side concave grooves 6a, 6b is 0.
I am trying to become. However, each suction side concave groove 4
The flow of the hydraulic oil in the a, 4b and the discharge side recessed grooves 6a, 6b is different on both sides of the gears 30, 31 depending on the asymmetry of each suction passage 5 for introducing the hydraulic oil, the presence or absence of communication of the discharge passage 7, and the like. They are not the same, and therefore, the pressure exerted on the gears 30 and 31 by the hydraulic oil in the suction-side recessed grooves 4a and 4b and the discharge-side recessed grooves 6a and 6b on both sides is different.
0 and 31 are moved to one side and are inclined in some cases.

In the prior art having the above-mentioned structure, there is a large flow of the hydraulic oil in the discharge side concave groove (discharge port) 6a communicating with the discharge passage 7 on the pump body 1 side, and each gear 3
The reason is that the relative speed with respect to the gears 30 and 31 is large because the relative speed with respect to the gears 0 and 31 is small and the discharge passage 7 on the pump cover 3 side is not communicated with the hydraulic oil in the discharge side concave groove 6b. As a result, the gears 30 and 31 are set at the discharge side concave groove 6b
In the vicinity of, the pump cover 3 side is pulled and tilted. For this reason, both gears 30 and 31 are brought into contact with the inner surface of the pump cover 3, and there is a problem that frictional resistance increases, energy loss occurs, and wear occurs. In particular, when the pump cover 3 is made of a light alloy (for example, aluminum) die-cast product in order to reduce the weight, the inner surface of the pump cover 3 is greatly worn and the working oil in the discharge passage 7 is discharged from the discharge-side concave groove 6b. The leakage to the suction passage 5 side causes a problem that the discharge performance of the oil pump is deteriorated. The present invention aims to solve each of these problems.

[0005]

To this end, an oil pump according to the present invention includes a housing in which an intake passage, a gear chamber and a discharge passage are formed, and a gear chamber of the housing rotatably and meshed with each other. It has an externally toothed drive gear and an internally toothed driven gear, and both side surfaces of a pair of gears are rotated so as to slide on both inner side surfaces of the gear chamber of the housing to rotate from the suction passage. In an oil pump that sucks hydraulic oil and discharges this hydraulic oil from the discharge passage, between the outer peripheral surface of the driven gear and the inner peripheral surface of the gear chamber that rotatably slides with this outer peripheral surface, the side surface of the driven gear and the gear chamber It is characterized in that a spiral groove for reducing sliding resistance between the inner surface and the inner surface is provided.

The spiral groove of the oil pump according to the invention described above is interposed between the inner side surface of the gear chamber and the side surface of the driven gear on the side where the driven gear is separated by the operation of the oil pump due to the relative rotation of the housing and the driven gear. It is preferable that the oil is moved between the inner side surface of the gear chamber on the side where the driven gear is pressed by the operation of the oil pump and the side surface of the driven gear.

The spiral groove of the oil pump according to the second aspect of the invention may be formed on at least one of the outer peripheral surface of the driven gear and the inner peripheral surface of the gear chamber that rotatably slides on the outer peripheral surface. It is preferable to form it on the outer peripheral surface.

Further, the oil pump according to the present invention comprises a housing having an intake passage, a gear chamber and a discharge passage,
A drive gear having external teeth and a driven gear having internal teeth, which are rotatably and meshed with each other, are provided in the gear chambers of the housing, and both side surfaces of the pair of gears are provided in both sides of the gear chamber of the housing. In an oil pump that sucks hydraulic oil from the suction passage by rotating while sliding on the side surface and discharges this hydraulic oil from the discharge passage, the inner peripheral surface of the drive gear and the member supporting the inner peripheral surface are A spiral groove for reducing sliding resistance between the side surface of the drive gear and the inner side surface of the gear chamber is provided between the outer peripheral surface and the side surface of the drive gear.

The spiral groove of the oil pump according to the invention of the preceding paragraph is interposed between the inner side surface of the gear chamber and the side surface of the drive gear on the side where the drive gear is separated by the operation of the oil pump due to the relative rotation of the housing and the drive gear. It is preferable that the working oil is moved between the inner side surface of the gear chamber, which is the side on which the drive gear is pressed by the operation of the oil pump, and the side surface of the drive gear.

The spiral groove of the oil pump according to the second aspect of the invention may be formed on at least one of the inner peripheral surface of the drive gear and the outer peripheral surface of the member supporting the inner peripheral surface.
It is preferably formed on the inner peripheral surface of the drive gear.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First, a first embodiment shown in FIGS. 1 to 5 will be described. The oil pump according to the first embodiment supplies hydraulic oil to an automatic transmission of an automobile, and mainly accommodates a drive gear 30, a driven gear 31 having internal teeth meshing with the drive gear 30, and both gears 30, 31. The housing H is formed of a pump body 10 and a pump cover 15 which are joined and fixed to each other.

As shown mainly in FIG. 1, both gears 30, 3 are provided on one flat side surface of the pump body 10 made of cast iron.
A circular, shallow accommodation recess 11 having a constant depth is formed to rotatably accommodate 1 and the inner bottom surface of the accommodation recess 11 has the same eccentricity between the gears 30 and 31 with respect to the center of the accommodation recess 11. A central hole 12 is formed so as to be eccentric by the amount and penetrate the pump body 10. The pump cover 15 made of aluminum is bolted to the pump body 10 by one flat side surface so as to cover the housing recess 11 in a liquid-tight manner. The housing recess 11 of the pump body 10 and the pump cover 15 covering the housing cover 11 cover both gears 30, 31. A gear chamber for accommodating the is formed. A tubular stator shaft 17, which is press-fitted and fixed in a central hole 16 formed coaxially with the central hole 12 of the pump body 10, is provided with a gap between the central shaft 12 and the central hole 12.
It goes through 0. A tubular input shaft 35 inserted between the stator shaft 17 and the center hole 12 is rotatably supported by a bearing bush 13 fixed to the inner surface of the center hole 12, and an oil seal 36 is provided between the input shaft 35 and the pump body 10. It is sealed by.

The drive gear 30 having external teeth and the driven gear 31 having internal teeth having one tooth larger than the drive gear 30 have the same thickness.
It has trochoidal teeth that mesh with each other, their sides and pump body 10 and pump cover 15
Both inner side surfaces of the gear chamber formed by are relatively slidably rotatable with a small clearance such that the hydraulic oil does not substantially leak. The drive gear 30 has an input shaft 3 on its inner peripheral surface.
5 A pair of keys 30a, which are supported by being fitted to the outer peripheral surface of the front end portion and project from the inner peripheral surface, are engaged with the key grooves 35a formed at the front end of the input shaft 35 and are rotationally driven. ing. An outer peripheral surface of the driven gear 31 is rotatably fitted and supported on an inner peripheral surface of the accommodation recess 11.

As shown mainly in FIG. 2, both gears 30, 31 are arranged between the gears 30, 31 arranged in the gear chamber.
From the contact position of the pitch line of the gears 30 and 31 to 180 degrees in the rotation direction of the gears 30 and 31, a suction region is formed in which the volume between the meshing teeth of the gears 30 and 31 gradually increases with rotation, and A discharge region is formed in which the volume between the teeth that mesh with each other 180 degrees in the direction opposite to the rotation direction from the contact position gradually decreases with rotation. As shown in FIGS. 1 and 2, openings are formed on both inner side surfaces of the gear chamber formed by the accommodating recess 11 of the pump body 10 and the pump cover 15 that covers the accommodating recess 11, along with a substantial portion corresponding to the suction region. A pair of suction ports (suction side concave grooves) 20a, 20b having the same shape and area are formed to face each other, and the inner edge and the outer edge of each suction port 20a, 20b are respectively the gears 30, 31. It matches the root circle of. Further, a suction passage 21 formed in the pump body 10 and the pump cover 15 for introducing hydraulic oil from a reservoir (not shown) is connected to the suction ports 20a and 20b.

On both inner side surfaces of the gear chamber, as shown in FIG. 2, discharge ports (discharge side concave grooves) having substantially the same shape and area of openings along corresponding portions corresponding to the discharge region.
25a and the discharge side concave groove 25b are formed so as to face each other. The inner edge and the outer edge of the discharge port 25a and the discharge-side groove 25b coincide with the root circles of the gears 30 and 31, respectively. The discharge port 25a communicates with a discharge passage 26 formed in the pump body 10 and the pump cover 15 for supplying hydraulic oil to a supply destination. However, the discharge side groove 2
5b is shallower than the discharge port 25a in order to avoid a fluid passage (not shown) formed in the pump cover 15, and is not communicated with the discharge passage 26.

As shown in FIGS. 3 and 4, the accommodating recess 1
On the outer peripheral surface of the driven gear 31, which is rotatably fitted to the inner peripheral surface of 1, the working oil interposed between the inner bottom surface of the housing recess 11 and one side surface of the driven gear 31 sliding with the inner bottom surface of the housing recess 11 is provided. Due to the relative rotation between the driven gear 31 and the housing H during the operation of the oil pump, the pump cover 15
A spiral groove 31a is formed between the driven gear 31 and the other side surface of the driven gear 31 that slides with the groove.

During operation of the oil pump, the drive gear 30 supported by the tip of the input shaft 35 is rotated clockwise as indicated by the double-dotted chain line arrow in FIG. 2, and the driven gear 31 is also rotated in the same direction. . As a result, the hydraulic oil in the reservoir passes through the suction passage 21 and the suction ports 20a on both sides,
It is sucked into the suction region between both gears 30 and 31 from 20b, is discharged from the discharge region into the discharge port 25a, and is supplied to the supply destination through the discharge passage 26. At this time, the discharge port 2 in which the discharge passage 26 on the pump body 10 side is communicated
There is a large flow of hydraulic oil in 5a,
1, the relative speed with respect to 1 is small, while the hydraulic oil in the discharge side concave groove 25b where the discharge passage 26 on the pump cover 15 side is not communicated stagnates and the relative speed with each gear 30, 31 increases, and so on. The pressure of the hydraulic oil in the discharge-side concave groove 25b becomes lower than the pressure of the hydraulic oil in the discharge port 25a. As a result, one side surface of both the gears 30 and 31 is separated from the inner bottom surface of the housing recess 11, and the other side surface is pressed against the inner surface of the pump cover 15.

However, the spiral groove 31a formed on the outer peripheral surface of the driven gear 31 is caused by the relative rotation between the driven gear 31 and the housing H during the operation of the oil pump.
The hydraulic oil interposed between one side surface of the driven gear 31 and the inner bottom surface of the housing recess 11 is drawn between the outer peripheral surface of the driven gear 31 and the inner peripheral surface of the housing recess 11 to drive the driven gear 3
It is fed between the other side surface of 1 and the pump cover 15 to form an oil film. As a result, the other side surface of the driven gear 31 that is about to come into contact with the inner surface of the pump cover 15 is floated from the inner surface of the pump cover 15 against the force due to the pressure difference between the discharge port 25a and the discharge side groove 25b. Since the pump cover 15 and the side surface of the driven gear 31 are lubricated by the fed working oil, the contact between the pump cover 15 and the side surface of the driven gear 31 is prevented.
The frictional resistance does not increase, resulting in energy loss or wear. Even if the aluminum pump cover 15 is used for weight reduction,
Also, the inner surface of the pump cover 15 is abraded and the working oil in the discharge passage 26 leaks from the discharge side concave groove 25b to the suction passage 21 side, so that internal leakage does not occur and the discharge performance of the oil pump does not deteriorate.

The inclination angle, the cross-sectional area and the number of the spiral grooves 31a are sufficiently levitated even where the side surface of the driven gear 31 is closest to the pump cover 15, and the frictional resistance between the driven gear 31 and the pump cover 15 is sufficiently increased. It may be set to a value that can be reduced to. It should be noted that the spiral groove 31a may be provided on the inner peripheral surface of the housing recess 11 into which the outer peripheral surface is fitted, instead of being provided on the outer peripheral surface of the driven gear 31, or may be provided on both. When provided on both sides, the spiral grooves intersect each other.

Next, a second embodiment shown in FIGS. 5 to 7 will be described. In the second embodiment, the drive gear 3
This embodiment is different from the first embodiment only in that the spiral groove 30b is also formed on the inner peripheral surface of 0 and the input shaft 35 for supporting the spiral groove 30b is extended. Therefore, this difference will be mainly described.
As shown in FIG. 5, the input shaft 35 having a key groove 35a is formed.
The tip of the pump is extended and the central hole 16 of the pump cover 15 is
It is rotatably supported by. Further, on the inner peripheral surface of the drive gear 30 fitted to the outer peripheral surface of the input shaft 35, the hydraulic oil interposed between the inner bottom surface of the housing recess 11 and one side surface of the drive gear 30 sliding with the inner bottom surface. Is drawn by the relative rotation between the drive gear 30 and the housing H during the operation of the oil pump, and the spiral groove 30b is formed between the pump cover 15 and the other side surface of the drive gear 30 that slides with the pump cover 15. ing.

When the oil pump operates, the drive gear 3
0 rotates with the input shaft 35, but both members 30,
Due to the relative rotation between the housing 35 and the housing H, one side surface of the drive gear 30, the drive gear 30, and the housing recess 11 are formed.
The hydraulic oil interposed between the inner surface and the inner bottom surface of the drive gear 30
The oil film is formed by being drawn into the spiral groove 30b formed on the inner peripheral surface of the pump, and sent between the other side surface of the drive gear 30 and the pump cover 15. As a result, like the driven gear 31, the other side surface of the drive gear 30 that is about to come into contact with the inner surface of the pump cover 15 is not floated from the inner surface of the pump cover 15 and does not come into direct contact therewith, and the pump cover 15 and the drive Since the space between the side surfaces of the gear 30 is lubricated by the fed working oil, frictional resistance does not increase and energy loss or wear does not occur, and the inner surface of the pump cover 15 wears. The hydraulic oil in the discharge passage 26 does not leak from the discharge-side concave groove 25b to the suction passage 21 side.

The spiral groove 30b may be provided not only on the inner peripheral surface of the drive gear 30 but also on the outer peripheral surface of the input shaft 35 with which the inner peripheral surface is fitted, or on both of them. Moreover, the inclination angle, the cross-sectional area, and the number of spiral grooves 30b are also
It may be set to a value such that the side surface of the drive gear 30 is sufficiently floated even at the position closest to the pump cover 15 and the frictional resistance between the drive gear 30 and the pump cover 15 is sufficiently reduced.

Also in the first embodiment described above, it is effective to provide the spiral groove 30b similar to that of the second embodiment on the inner peripheral surface of the drive gear 30. in this case,
Part of the hydraulic oil sent to the pump cover 15 side through the spiral groove 30b leaks from the gap between the input shaft 35 and the stator shaft 17, but there is a certain amount of flow resistance in this gap, and therefore, within this gap. Since the working oil pressure at the end of the pump cover 15 on the side of the pump cover 15 rises, a part of the working oil sent by the spiral groove 30b is sent between the other side surface of the drive gear 30 and the pump cover 15 to form an oil film.

Next, a third embodiment shown in FIGS. 8 and 9 will be described. In the third embodiment as well, similar to the first embodiment, mainly the drive gear 30, the driven gear 31 having internal teeth meshing with the drive gear 30, and the both gears 30, 3 are provided.
Housing H that forms a gear chamber that rotatably accommodates 1
The housing H is formed by the pump body 10 and the pump cover 15.
0, the driven gear 31, and the structure of the portion directly related thereto are different from those of the first embodiment.

As shown mainly in FIG. 8, the accommodating recess 11 for accommodating both gears 30 and 31 formed on one flat side surface of the pump body 10 is the same as that of the first embodiment, and is eccentrically centered to have a central hole. 12 is formed, but is different in that a crescent-shaped partition 14 described below is formed so as to project from the inner bottom surface of the accommodation recess 11. A pump cover 15 that covers the pump body 10 in a liquid-tight manner has an inner surface abutting against the top surface of the partition 14, and a central hole 16 is formed coaxially with the central hole 12.

The drive gear 30 and the driven gear 31 have involute tooth-shaped teeth that mesh with each other, and the number of teeth of the driven gear 31 is 2 more than the number of teeth of the drive gear 30.
Greater than a tooth. The drive gear 30 is rotatably supported by the center holes 12 and 16 of the pump body 10 and the pump cover 15 via an integrally formed input shaft 35. As shown in FIG. 9, the tooth tips of the gears 30 and 31 are slidable with a slight gap between the inner peripheral surface and the outer peripheral surface of the crescent-shaped partition 14.

As shown in FIG. 9, between the gears 30 and 31 disposed in the gear chamber, the gears are provided between the contact position of the pitch lines of the gears 30 and 31 and one tip of the partition 14. A suction region is formed in which the volume between the meshing teeth of 30, 31 is gradually increased with the rotation, and both gears 3 are provided between the contact position of the pitch line and the other end of the partition 14.
A discharge region is formed in which the volume between the meshing teeth of 0 and 31 gradually decreases with rotation. Similar to the first embodiment, on both inner side surfaces of the gear chamber formed by the accommodating recess 11 of the pump body 10 and the pump cover 15 covering the accommodating recess 11, along the corresponding portion corresponding to the suction region, the opening portion is formed. Ports 20a, 20b having the same shape and area
Are formed to face each other, and the suction ports 20a, 20
The suction passage 21 is connected to b.

Further, as shown in FIGS. 8 and 9, on both inner side surfaces of the gear chamber, the discharge port 2 having substantially the same shape and area of the opening is formed along a considerable portion corresponding to the discharge region.
5a and the discharge side concave groove 25b are formed so as to face each other. The discharge port 25a communicates with a discharge passage 26 formed in the pump body 10 and the pump cover 15 for supplying hydraulic oil to a supply destination. However, the discharge side groove 25
Similar to the first embodiment, b is shallower than the discharge port 25a and is not connected to the discharge passage 26.

Similar to the first embodiment, hydraulic oil interposed between the driven gear 31 and the inner bottom surface and outer peripheral surface of the housing recess 11 is also provided on the outer peripheral surface of the driven gear 31 of the third embodiment. A spiral groove 31a is formed between the driven gear 31 and the pump cover 15 by the relative rotation between the driven gear 31 and the housing H when the oil pump is operated. However, the input shaft 35 of the third embodiment is formed integrally with the drive gear 30,
The input shaft 35 is connected to the pump body 10 and the pump cover 15.
Since it is supported by the central holes 12 and 16, there is no risk of tilting like the driven gear 31, and movement in the axial direction is also restricted by the input shaft 35. Therefore, what corresponds to the spiral groove 30b of the second embodiment that prevents the drive gear 30 from coming into contact with the inner bottom surface of the housing recess 11 or the pump cover 15 is unnecessary.

When the drive gear 30 supported at the tip of the input shaft 35 is rotated clockwise as indicated by the double-dashed line arrow in FIG. 9, the driven gear 31 is also rotated in the same direction, and the working oil is sucked in. Intake ports 20 on both sides through passage 21
a, 20b is sucked into the suction region between the gears 30 and 31, and discharged from the discharge region into the discharge port 25a,
It is supplied to the supply destination through the discharge passage 26. At this time, for the same reason as described in the first embodiment, the pressure of the hydraulic oil in the discharge-side concave groove 25b becomes smaller than the pressure of the hydraulic oil in the discharge port 25a, and one side surface of the driven gear 31. Is pulled away from the inner bottom surface of the housing recess 11 in the vicinity of the discharge port 25a, and the other side surface of the driven gear 31 tends to be pressed against the inner surface of the pump cover 15.

However, since the spiral groove 31a is formed on the outer peripheral surface of the driven gear 31, it is interposed between one side surface of the driven gear 31 and the inner bottom surface of the pump body 10 for the same reason as in the first embodiment. The working oil thus formed is sent between the other side surface of the driven gear 31 and the inner surface of the pump cover 15 to form an oil film. As a result, the other side surface of the driven gear 31 is floated from the inner surface of the pump cover 15 and does not come into direct contact with the pump cover 15 even at the position closest to the pump cover 15, so that the operation between the pump cover 15 and the side surface of the driven gear 31 is performed. Since it is lubricated with oil, frictional resistance does not increase and energy loss or wear does not occur. Even when the aluminum pump cover 15 is used to reduce the weight, as in the case of the first embodiment, the hydraulic oil in the discharge passage 26 is worn out from the discharge side concave groove 25b to the suction passage 2 as in the case of the first embodiment.
It is also possible to prevent the discharge performance of the oil pump from being deteriorated due to internal leakage such as leakage to the first side.

As described in the above three embodiments, in the case of the discharge port 25a in which the discharge passage 26 communicates and the discharge side groove 25b in which the discharge passage 26 does not communicate, the inside of the discharge side groove 25b is formed. The hydraulic oil pressure is the discharge port 2
Since it is smaller than the pressure of the hydraulic oil in 5a, the respective gears 30, 31 (only the driven gear 31 in the case of the third embodiment) are attracted or inclined to the discharge side concave groove 25b side as they are, and the above-mentioned respective The embodiment has been described for such a case. However, each intake port 20
Even when the openings of a and 20b have the same shape and the suction passages 21 communicate with each other, the suction ports 20 face each other.
The flow of the hydraulic oil passing through the insides of a and 20b is not completely the same on both sides of both gears 30 and 31 due to the asymmetry of the respective intake passages 21 for introducing the hydraulic oil into each, and the intake ports 20a and 20a. Intake passage 21 only on one side of 20b
Even if the other side is made to communicate with each other and the other side is formed as a discharge side concave groove which does not communicate with the suction passage 21, it is not completely the same on both sides of both gears 30 and 31.

In such a case, each suction port 20a, 2
Since the hydraulic oil in 0b exerts different pressures on the gears 30 and 31, the gears 30 and 31 (only the driven gear 31 in the case of the third embodiment) is biased to one side or inclined, and depending on the case, The degree may not be negligible. The present invention can be applied to such a case. The situation is the same even when the discharge-side concave groove 25b is used as a discharge port that communicates with the discharge passage 26 in each of the above-described embodiments.

[0034]

As described above, according to the first aspect of the present invention, the side surface of the driven gear and the gear chamber are provided between the outer peripheral surface of the driven gear and the inner peripheral surface of the gear chamber which rotatably slides on the outer peripheral surface. Since the spiral groove that reduces the sliding resistance with the inner side surface is provided, the frictional resistance between the outer peripheral surface of the driven gear and the inner peripheral surface of the gear chamber increases, resulting in energy loss and wear. There is nothing to do. Even if all or part of the housing is lightly alloyed to reduce weight, the inner surface of the lightly alloyed gear chamber will wear due to sliding with the driven gear, and the hydraulic oil in the discharge passage will become The internal leakage of the oil pump does not reduce the discharge performance of the oil pump.

In the invention of the preceding paragraph, the spiral groove holds the hydraulic oil interposed between the inner side surface of the gear chamber and the side surface of the driven gear on the side where the driven gear is separated by the operation of the oil pump due to the relative rotation of the housing and the driven gear. According to the one in which the driven gear is moved between the inner surface of the gear chamber on the side where the driven gear is pressed by the operation of the oil pump and the side surface of the driven gear, according to the inner surface of the gear chamber on the side where the driven gear is pressed and the driven gear. The hydraulic oil moved by the spiral groove is fed between the side surfaces to form an oil film. As a result, the side surface of the driven gear is not floated from the inner side surface of the gear chamber against which it is pressed and does not come into direct contact with it, and is lubricated by the hydraulic oil that has been sent in, increasing frictional resistance and causing energy loss, It will not cause wear and the above-mentioned respective effects can be obtained.

In the invention of the above-mentioned 2nd aspect, if the spiral groove is formed on at least one of the outer peripheral surface of the driven gear and the inner peripheral surface of the gear chamber which rotatably slides on the outer peripheral surface, the above-mentioned respective operational effects can be obtained. can get. If the spiral groove is formed on the outer peripheral surface of the driven gear, the spiral groove can be formed very easily.

According to the second invention, between the inner peripheral surface of the drive gear and the outer peripheral surface of the member supporting the inner peripheral surface, between the side surface of the drive gear and the inner surface of the gear chamber. Since the spiral groove that reduces the sliding resistance is provided, the frictional resistance between the inner peripheral surface of the drive gear and the outer peripheral surface of the member that supports the drive gear increases, resulting in energy loss and wear. Things will disappear. Even if all or part of the housing is lightly alloyed to reduce weight, the inner surface of the lightly alloyed gear chamber wears due to sliding with the drive gear, causing the hydraulic oil in the discharge passage to pass through the suction passage. The discharge performance of the oil pump does not deteriorate due to the internal leakage of leaking inside.

In the invention of the preceding paragraph, the spiral groove is interposed between the inner side surface of the gear chamber and the side surface of the drive gear on the side where the drive gear is separated by the operation of the oil pump due to the relative rotation of the housing and the drive gear. According to the one in which the operating oil is moved between the inner side surface of the gear chamber on the side where the drive gear is pressed by the operation of the oil pump and the side surface of the drive gear, the gear chamber on the side where the drive gear is pressed. The hydraulic oil moved by the spiral groove is sent between the inner surface of the drive gear and the side surface of the drive gear to form an oil film. As a result, the side surface of the drive gear is no longer floated from the inner side surface of the gear chamber against which it is pressed and does not come into direct contact with it, but is lubricated by the hydraulic oil that has been sent in, increasing frictional resistance and causing energy loss. No wear is caused, and the above-mentioned respective effects can be obtained.

In the invention of the above-mentioned item 2, if the spiral groove is formed on at least one of the outer peripheral surface of the drive gear and the inner peripheral surface of the gear chamber which rotatably slides on the outer peripheral surface, the above-mentioned respective operational effects. Is obtained.

[Brief description of drawings]

FIG. 1 is a sectional view of a central portion of a first embodiment of an oil pump according to the present invention.

2 is a front view of the pump cover taken along line 2-2 of FIG. 1. FIG.

FIG. 3 is a perspective view showing a state in which a drive gear and a driven gear according to the first embodiment are combined.

FIG. 4 is a side view of the driven gear according to the first embodiment.

FIG. 5 is a sectional view of a central portion corresponding to FIG. 1 of the second embodiment of the oil pump according to the present invention.

FIG. 6 is a perspective view corresponding to FIG. 3 of the second embodiment.

FIG. 7 is a sectional view showing a state in which a drive gear and a driven gear according to the second embodiment are combined.

FIG. 8 is a sectional view of a central portion of a third embodiment of the oil pump according to the present invention.

9 is a front view of the central portion of the pump cover taken along line 7-7 of FIG.

FIG. 10 is a sectional view of a central portion of an example of an oil pump according to the related art.

11 is a front view of the central portion of the pump cover taken along line 11-11 of FIG.

[Explanation of symbols]

21 ... suction passage, 26 ... discharge passage, 30 ... drive gear, 30b ... spiral groove, 31 ... driven gear, 31a ... spiral groove, 35 ... member (input shaft), H ... housing.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshinori Shibayama             10 Akane, Takane, Fujii-cho, Anjo City, Aichi Prefecture             N AW Co., Ltd. F-term (reference) 3H041 AA02 BB03 CC07 CC13 CC17                       CC18 DD05                 3H044 AA02 BB03 CC07 CC12 DD05                       DD11 DD23

Claims (8)

[Claims] 1. A housing having an intake passage, a gear chamber and a discharge passage formed therein, and an externally toothed drive gear and an internally toothed driven gear rotatably and meshed with each other in the gear chamber of the housing. Both sides of each of the pair of gears are slidably rotated on both inner side surfaces of the gear chamber of the housing to suck the working oil from the suction passage, and discharge the working oil. In an oil pump that discharges from a passage, between an outer peripheral surface of the driven gear and an inner peripheral surface of the gear chamber that rotatably slides on the outer peripheral surface, between a side surface of the driven gear and an inner surface of the gear chamber. An oil pump having a spiral groove for reducing sliding resistance. 2. The oil pump according to claim 1, wherein the spiral groove and the inner surface of the gear chamber on the side where the driven gear is separated by the operation of the oil pump due to the relative rotation of the housing and the driven gear. The operating oil interposed between the side surfaces of the driven gear is moved between the inner surface of the gear chamber, which is the side on which the driven gear is pressed by the operation of an oil pump, and the side surface of the driven gear. Oil pump. 3. The oil pump according to claim 1 or 2, wherein the spiral groove is at least one of an outer peripheral surface of the driven gear and an inner peripheral surface of the gear chamber that rotatably slides on the outer peripheral surface. An oil pump characterized by being formed on one side, 4. The oil pump according to any one of claims 1 to 3, wherein the spiral groove is formed on an outer peripheral surface of the driven gear. 5. A housing in which an intake passage, a gear chamber and a discharge passage are formed, and a drive gear having external teeth and a driven gear having internal teeth, which are rotatably arranged in mesh with each other in the gear chamber of the housing. Both sides of each of the pair of gears are slidably rotated on both inner side surfaces of the gear chamber of the housing to suck the working oil from the suction passage, and discharge the working oil. In an oil pump that discharges from a passage, sliding between the side surface of the drive gear and the inner side surface of the gear chamber between the inner peripheral surface of the drive gear and the outer peripheral surface of a member supporting the inner peripheral surface. An oil pump having a spiral groove for reducing resistance. 6. The oil pump according to claim 5, wherein the spiral groove has an inner surface on the side where the drive gear is separated by the operation of the oil pump due to the relative rotation of the housing and the drive gear. And the side surface of the drive gear, the operating oil is moved between the inner side surface of the gear chamber and the side surface of the drive gear on the side where the drive gear is pressed by the operation of the oil pump. An oil pump characterized by that. 7. The oil pump according to claim 5 or 6, wherein the spiral groove is formed on at least one of an inner peripheral surface of the drive gear and an outer peripheral surface of the member supporting the inner peripheral surface. An oil pump characterized by 8. The oil pump according to any one of claims 5 to 7, wherein the spiral groove is formed on an inner peripheral surface of the drive gear.