JP3754580B2 - Internal gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an internal gear pump, and more particularly to an internal gear pump suitable for use in a pump for an automatic transmission of an automobile.
[0002]
[Prior art]
In a conventional internal gear pump, claws are formed to protrude at four points on the circumference of the tip of an oil pump drive hub as a drive shaft, and each claw is passed through an external gear as a rotational driving force transmission part. When the external gear is rotationally driven by the oil pump drive hub, the internal gear that is in mesh with the external gear is rotationally driven together with the external gear, and the suction port. The oil is conveyed from the suction area of the pump chamber formed between the two gears to the discharge area and discharged from the discharge port. (For example, refer to Japanese Utility Model Laid-Open No. 5-14576).
[0003]
[Problems to be solved by the invention]
However, in such a conventional internal gear pump, as the oil pump drive hub is repeatedly driven and stopped, the crest of the claw of the oil pump drive hub repeatedly collides with the inner surface of the slot. The part wears and a recess is formed in which the tip ridge of the claw engages. The engagement of the ridge of the tip of the claw with this recess causes the oil pump drive hub to move toward the external gear by the pressure action of the torque converter. Due to the movement, the external gear is pressed in the axial direction toward the pump body, and seizure is likely to occur.
[0004]
The present invention eliminates the engagement of the tip ridge of the drive shaft with the external gear, reduces the pressing of the external gear in the axial direction by the drive shaft, and suppresses the occurrence of seizure of the external gear. It is an object to provide a gear pump.
[0005]
[Means for Solving the Problems]
For this reason, in the present invention, an internal gear having internal teeth is rotatably accommodated in an accommodation hole in the pump body constituted by the pump housing and the lid member, and the external gear that is in meshingly engaged with the internal teeth of the internal gear. An external gear having teeth is housed in an eccentric manner inside the internal gear, and the external gear is formed with an axial protrusion that protrudes in the axial direction, and is engaged with the drive shaft at one end of the axial protrusion. and the rotation driving force of the drive shaft to form formed a rotational driving force transmitting portion is transmitted, a recess in a location where the tip edge portion of the continuous inwardly drive shaft in the axial direction of the rotational driving force transmitting portion is located The concave portion is formed so as not to contact the tip ridge portion of the drive shaft.
[0006]
According to the internal gear pump of the present invention, when the drive shaft is rotationally driven, the rotational drive force of the drive shaft is transmitted via the rotational drive force transmission portion of the external gear, and the external gear is rotationally driven and externally driven. The internal gear that is in mesh with the tooth gear is rotationally driven together with the external gear to obtain a pump operation. The external gear forms a recess at the position where the tip ridge of the drive shaft is located and is not in contact with the tip ridge of the drive shaft. Even if the drive shaft is repeatedly driven and stopped, the tip of the drive shaft is repeated. There will be no depression where the parts engage. For this reason, even if the drive shaft moves in the axial direction toward the external gear during pump operation, the tip ridge of the drive shaft can be engaged with the external gear. The pressing in the direction can be reduced, and the occurrence of seizure of the external gear can be suppressed.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of the present invention applied to a pump of an automatic transmission of an automobile will be described with reference to the drawings.
1 to 3, reference numeral 1 denotes a pump housing, which has a bottomed receiving hole 2 formed at one end surface 1A. Reference numeral 3 denotes a lid member, which is in contact with one end surface 1A of the pump housing 1 so as to close the opening of the housing hole 2 and fastened to the pump housing 1 with a plurality of bolts 4. The pump housing 1 and the lid member 3 constitute a pump body 5. Reference numeral 6 denotes an internal gear, which has 11 internal teeth 6A, and is accommodated in the accommodation hole 2 so as to be freely rotatable. Reference numeral 7 denotes an external gear having nine external teeth 7 </ b> A that are in mesh with the internal teeth 6 </ b> A and housed eccentrically in the internal gear 6. A fixed shaft 8 is fixed to the pump housing 1 and rotatably supports an external gear 7 via a bearing bush 9. A crescent-shaped partition member 10 is formed integrally with the pump housing 1 and protrudes from the bottom surface of the housing hole 2 toward the opening. The suction region P1 and the discharge region of the pump chamber formed between the two gears 6 and 7 are provided. Partitions P2.
[0008]
11A is a suction port formed in the bottom of the receiving hole 2 and 11B is a suction port formed in the recess on one end surface 3A of the lid member 3. Both suction ports 11A and 11B enter the suction region P1 of the pump chamber from both sides in the axial direction. Each of the openings opens and is connected to one suction passage 12 inside the pump housing 1. Reference numeral 13A denotes a discharge port, which is formed at the bottom surface of the receiving hole 2 at a substantially symmetrical position in the radial direction with respect to the suction port 11A, opens from one side in the axial direction to the discharge region P2 of the pump chamber, and It is connected to the discharge path 14 internally. Although not shown, a discharge port is formed in the one end surface 3A of the lid member 3 at a substantially symmetrical position in the radial direction with respect to the suction port 11B, and this discharge port is formed in the discharge region P2 of the pump chamber on the other side in the axial direction. While opening more, it is connected to the discharge path 14 inside the pump housing 1.
[0009]
Reference numeral 15 denotes an oil pump drive hub as a drive shaft, which is formed in a hollow cylindrical shape, is rotatably supported on the cover member 3 through the bearing bush 16 concentrically with the external gear 7, and is splined on the inner peripheral surface of the tip. 15A is formed. The external gear 7 is integrally formed with an axial projecting portion 7A having a smaller diameter than the oil pump drive hub 15 projecting in the axial direction into the hollow portion at the end of the oil pump drive hub 15, and an outer peripheral surface on one end side of the axial projecting portion 7A. The spline 7B that engages with the spline 15A of the oil pump drive hub 15 is formed as a rotational driving force transmitting portion. The external gear 7 is connected to the inner side of the spline 7B in the axial direction, and the radial inner ridge portion 15B (tip ridge portion of the drive shaft) at the tip end forming the spline 15A of the oil pump drive hub 15 is located. A recess 7C is formed by annularly recessing the outer circumferential surface of the axial projection 7A, and the recess 7C is provided in a non-contact manner with the radially inward ridge 15B at the tip where the spline 15A of the oil pump drive hub 15 is formed. .
[0010]
Next, the operation of this configuration will be described.
When the oil pump drive hub 15 is rotationally driven, the rotational driving force of the oil pump drive hub 15 is transmitted to the external gear 7 through the splines 15A and 7B, and the external gear 7 is rotationally driven. The internally geared internal gear 6 is rotationally driven, and the oil in the suction path 12 is sucked into the suction area P1 of the pump chamber from the suction ports 11A and 11B and is transported to the discharge area P2, and is discharged to the discharge path 14 from the discharge port 13A. Discharge and pump operation is obtained.
[0011]
With this operation, the external gear 7 forms a recess 7C at the position where the radially inner ridge 15B at the tip of the oil pump drive hub 15 is located, and the radially inner ridge 15B at the tip of the oil pump drive hub 15. In the non-contact state, even if the rotation driving and stopping of the oil pump drive hub 15 are repeated, there is no depression that engages with the radially inward ridge 15B at the tip of the oil pump drive hub 15. Even if the oil pump drive hub 15 is moved in the axial direction toward the external gear 7 due to the pressure action of a torque converter (not shown), the radially inward ridge 15B at the tip of the oil pump drive hub 15 is connected to the external gear 7. Since it can do without engaging, the pressing of the external gear 7 in the axial direction by the oil pump drive hub 15 can be reduced, and seizure of the external gear 7 can be suppressed. It can be.
[0012]
[0013]
[0014]
In the embodiment of the present invention, the difference in the number of teeth of the gears 6 and 7 is 2, and the crescent-shaped partition member 10 for partitioning the suction region P1 and the discharge region P2 of the pump chamber formed between the gears is provided. Although provided, the difference in the number of teeth of the two gears is set to 1, and the partition member is not provided, and it is possible to partition the suction region and the discharge region of the pump chamber with the tooth tips of both gears facing each other through a minute gap. It is.
[0015]
【The invention's effect】
As described above, according to the present invention, the external gear is formed with the axial protrusion that protrudes in the axial direction, and one end of the axial protrusion is engaged with the drive shaft to transmit the rotational driving force of the drive shaft. that the rotation driving force to form formed a transmitting portion, a recess in a location where the tip edge portion of the drive shaft continues to the inside of the axial direction of the rotational driving force transmitting portion is located, the recess tip edge portion of the drive shaft In this way, even if the drive shaft is repeatedly driven and stopped, the external gear does not have a recess that engages with the tip ridge of the drive shaft. Even if it moves in the axial direction toward the gear, the tip ridge of the drive shaft can be engaged with the external gear, and the pressing of the external gear in the axial direction by the drive shaft can be reduced. The occurrence of seizure can be suppressed.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view of an internal gear pump showing an embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along line AA in FIG.
FIG. 3 is an enlarged cross-sectional view taken along line BB in FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Pump housing 2 Housing hole 3 Lid member 5 Pump main body 6 Internal gear
7 External gear 7B Spline (Rotation drive force transmission part)
7 C recess <br/> 1 5 OIL pump drive hub (drive shaft)
15B Radial inward ridge at the tip (tip ridge)
17B key (rotation drive force transmission part)
25B Radial outward ridge at the tip (tip ridge)

Claims (1)

An external gear having an external tooth that rotatably accommodates an internal gear having internal teeth in an accommodation hole in a pump body constituted by a pump housing and a lid member, and that meshes with the internal teeth of the internal gear. Is housed eccentrically in the internal gear, and the external gear is formed with an axial protrusion protruding in the axial direction. One end of the axial protrusion is engaged with the drive shaft to rotate the drive shaft. the driving force form formed a rotational driving force transmitting portion is transmitted, a recess in a location where the tip edge portion of the drive shaft continues to the inside of the axial direction of the rotational driving force transmitting portion is located, the recess drive An internal gear pump characterized by being provided in non-contact with the tip ridge of the shaft.

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