JPH1150972A - Oil pump structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve durability of an oil seal by easily releasing high-pressure oil unavoidably leaking from a side clearance between a rotor and a pump housing by a simple drain structure, in an oil pump in which an inner rotor to be housed in the pump housing provided on a case is spline-fitted to a driving shaft rotatably supported to the case, and a part between the releasing part on one side in the axial direction of the pump housing and the driving shaft is sealed by the oil seal. SOLUTION: The tooth height of at least a part of spline teeth 6S of either a driving shaft 1 or an inner rotor 6 is decreased, drain passages (d) are formed on a part of a spline fitting part between the driving shaft 1 and the inner rotor 6, and the inside part of an oil seal is communicated with an inner space of a case through the drain passages (d).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a pump, and more particularly, to a case in which a pump housing is rotatably supported on a pump housing, and an inner rotor accommodated in the pump housing is spline-fitted to the drive shaft. The present invention relates to a structure of an oil pump in which a gap between an opening on one axial side of a pump housing and the drive shaft is sealed by an oil seal.

[0002]

2. Description of the Related Art An oil pump having the above-described structure is installed, for example, in a transmission case of a continuously variable transmission for a vehicle, and is used as a pump for supplying hydraulic oil to a hydraulic drive unit for shifting.
It has been widely known from the past (for example, see JP-A-6-2294).
No. 48).

[0003]

In the above-mentioned conventional oil pump, high-pressure oil inevitably leaks from a side clearance between the rotor and the pump housing, and the leaked oil flows between the oil pump and the oil seal. There is a concern that the oil seal may remain in a high pressure state in the intervening space and impair the durability of the oil seal.

Therefore, conventionally, a hole serving as a drain passage for communicating the above space with the atmosphere side is provided in the case. However, the special construction of the drain hole complicates the case structure accordingly, and specially requires drilling and the like. For example, there was a problem that the cost increased as a whole. In addition, it is necessary to separate the oil seal from the oil pump in order to secure a space for the drain hole, and there is also a problem that the case becomes bulky in the axial direction of the drive shaft.

[0005] The present invention has been made in view of such circumstances, and has as its object to provide an oil pump structure which can solve the above-mentioned problems of the conventional structure with a simple structure at once.

[0006]

In order to achieve the above object, according to the present invention, a pump housing is provided in a case which rotatably supports a drive shaft, and an inner rotor housed in the pump housing is provided with the pump rotor. In an oil pump structure in which the drive shaft is spline-fitted to the drive shaft and an opening between the one axial side of the pump housing and the drive shaft is sealed by an oil seal, at least one of the drive shaft and the inner rotor is provided. Lowering the tooth height of at least a part of the spline teeth, forming a drain passage in a part of the spline fitting portion between the drive shaft and the inner rotor, and passing the inner portion of the oil seal through the drain passage to the case. It is characterized by communicating with the internal space. In the present invention, "reducing the tooth height of some of the spline teeth" includes making the tooth height of some of the teeth zero, that is, making some of the splines missing teeth.

According to the above feature, a part of the spline fitting portion between the drive shaft and the inner rotor (that is, between the spline tooth having a low tooth height and the spline groove facing the spline tooth) is linearly extended along the axial direction. Since the drain passage extending in the shape of a circle is formed, high-pressure oil that inevitably leaks from the side clearance between the rotor and the pump housing is easily released into the case through the drain passage,
The disadvantage that the high-pressure leakage oil accumulates in the space between the oil pump and the oil seal and impairs the durability of the oil seal is avoided. Furthermore, since it is not necessary to form a high-pressure oil drain passage on the case side, the case structure is not complicated, and it is also necessary to make a special hole or the like on the case side to form the drain passage. This eliminates the need for a space for the drain passage, and makes it possible to arrange the oil seal as close as possible to the oil pump.

According to a second aspect of the present invention, in addition to the above features, at least one bearing provided between the drive shaft and the case is disposed in a passage for the oil returning to the internal space of the case via the drain passage. According to this feature, the lubrication of the bearing is efficiently performed by effectively utilizing the leaked oil discharged into the case through the drain passage.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be specifically described below based on embodiments of the present invention illustrated in the accompanying drawings.

In the accompanying drawings, FIG. 1 shows a first embodiment of the present invention.
FIG. 2 is a longitudinal sectional view (a sectional view taken along line 1-1 of FIG. 2) of a pump showing an embodiment, FIG. 2 is an enlarged sectional view taken along a line 2-2 of FIG. 1, and FIG. It is sectional drawing similar to.

First, a first embodiment of the present invention will be described with reference to FIGS. In a transmission case C of the belt-type continuously variable transmission T, an input shaft 1 as a drive shaft and an output shaft (not shown) are rotatably supported, respectively, and a split having a variable effective radius is provided between both shafts. A belt transmission mechanism B using a mold pulley is interposed. The input shaft 1 is connected to the crankshaft of the engine in an interlocked manner, and the rotation of the input shaft 1 is changed by the belt transmission mechanism B and transmitted to the output shaft side.

A drive pulley 2 of a belt transmission mechanism B is fitted and supported on the input shaft 1 so as to be able to rotate integrally therewith. A flywheel FW with a torsional damper detachable from the input shaft 1 is further provided outside the input shaft 1. The high-pressure oil discharged from the oil pump P is appropriately adjusted in pressure by a control circuit (not shown) and supplied to a shift hydraulic drive unit or a forward / reverse switching hydraulic clutch or the like (not shown) of the continuously variable transmission T. Is done.

The oil pump P is constituted by a trochoid pump in the illustrated example. A pump housing 3 is detachably fixed to the housing body 4 and a pump chamber is provided between the housing body 4 and the housing body 4. And a pump cover 5 to be defined. The housing body 4 is formed integrally with an end wall of the case body Cm of the transmission case C, and the pump cover 5 is detachably joined to the case body Cm. The input shaft 1 is formed integrally with Cs, and the pump housing 3 passes through the pump shaft 3. The pump housing 3 has an inner rotor 6 having rotor outer teeth 6t on its outer periphery.
And an outer rotor 7 which has inner rotor teeth 7t meshing with the outer rotor teeth 6t to inscribe the inner rotor 6 in an eccentric state by a predetermined amount e.

The outer rotor 7 is rotatably fitted and supported on a bearing ring 5a fitted and fixed to the inner periphery of the pump cover 5. The inner circumference of the inner rotor 6 is spline-fitted to the outer circumference of the input shaft 1 that penetrates the inner rotor 6 and always rotates integrally with the input shaft 1. Although not shown, a suction port connected to an oil reservoir at the bottom of the transmission case C and a discharge port connected to the control circuit are formed at appropriate places of the pump housing 3 so as to open to the pump chamber.

An annular oil seal is provided between the open portion on one axial side of the pump housing 3 (in the illustrated example, an open portion 5b formed in the pump cover 5 so as to surround the input shaft 1) and the input shaft 1. Sealed with S. This oil seal S
Is an annular retainer 8 for reinforcing the outer peripheral portion thereof, and a rubber material or the like having a lip portion 9a formed annularly so as to integrally embed the retainer 8 and having an inner periphery closely fitted to the outer periphery of the input shaft 1. Ring 9 made of an elastic material and an annular spring 10 for pressing the lip 9a against the outer periphery of the input shaft 1.
The outer peripheral portion of the oil seal S is press-fitted and fixed to the inner peripheral surface of the opening 5 b of the pump cover 5.

At least some of the spline teeth 6s' engraved on the inner peripheral surface of the inner rotor 6 have a lower tooth height than other spline teeth 6s (ie, normal spline teeth 6s). In particular, in the illustrated example, as shown in FIG. 2, some spline teeth 6s' are formed with missing teeth (that is, so that the tooth height becomes zero). On the other hand, a normal spline tooth 1 s having a uniform tooth height is engraved on the outer peripheral surface of the input shaft 1. Thus, a part of the spline fitting portion between the inner rotor 6 and the input shaft 1 (that is, between the toothless portion 6s' of the inner rotor 6 and the spline groove portion 1sg on the outer periphery of the input shaft 1 opposed to the spline fitting portion) is provided. A drain passage d which is linearly extended along the direction and is open at both ends is formed.
Through the oil seal S and the transmission case C
High pressure oil unavoidably leaking from the side clearance 11 between the rotors 6, 7 and the pump housing 3 is easily discharged into the case C through the drain passage d.

A cylindrical portion 4a is provided at the inner end of the housing body 4.
The drive pulley 2 and the input shaft 1 are rotatably fitted to and supported by the cylindrical portion 4 a via a bearing 12. The bearing 12 is opposed to and close to the open end on the other axial side of the pump housing 3, and the drain passage passes through an annular gap between the open portion (ie, the opening 4 b of the housing body 4) and the input shaft 1. d is located on the path of the oil returned into the transmission case C. Thereby, the bearing 12 of the drive pulley 2 is efficiently lubricated by effectively utilizing the return oil. The shaft portion 2a of the drive pulley 2, on which the bearing 12 is directly fitted, is formed with a lateral hole 13 for guiding the oil flowing from the drain passage d along the outer periphery of the input shaft 1 to the bearing 12 side. . Although not shown, a bearing for rotatably supporting the input shaft 1 is provided between the input shaft 1 and the transmission case C at other portions as appropriate.

Next, the operation of this embodiment will be described. When the engine (not shown) is operating and the clutch is engaged, the rotation of the engine is transmitted to the wheels via the continuously variable transmission T, and at the same time, the input shaft 1 of the transmission T
The oil pump P, which is directly connected to and rotates, supplies high-pressure oil to a shift hydraulic drive unit (not shown) or the like.

At this time, each rotor 6 of the oil pump P
Side clearance 1 between 7 and pump housing 3
Although a small amount of high-pressure oil leaks inevitably from 1, a part of the spline fitting portion between the inner rotor 6 and the input shaft 1 has two ends corresponding to the toothless portion 6 s ′ of the inner rotor 6. Is opened and the drain passage d extending linearly is formed, so that the high-pressure leaking oil can be easily discharged into the case C through the drain passage d. Therefore, the disadvantage that the high-pressure leakage oil accumulates in the space between the oil pump P and the oil seal S and impairs the durability of the oil seal S is reliably avoided. Moreover, it is not necessary to specially form a drain passage for high-pressure leakage oil on the transmission case C side, and it is not necessary to perform a special drilling or the like on the transmission case C side for forming the drain passage.
Further, since no space is required for the drain passage, the oil seal S can be disposed as close to the oil pump P as possible, and the transmission case C itself can be reduced in the axial direction of the input shaft 1 accordingly.

If some of the spline teeth 6s' are missing teeth as in this embodiment, a relatively large passage cross-sectional area of the drain passage d formed corresponding to the missing teeth is ensured. Therefore, there is an advantage that the leaked oil can be returned smoothly and smoothly through the passage d.

Next, a second embodiment will be described with reference to FIG. In the second embodiment, instead of omitting a part of the spline teeth 6s' on the inner periphery of the inner rotor 6, the tooth height of at least a part of the spline teeth 6s "is changed to a normal spline tooth (in the illustrated example, other spline teeth). It is designed to be slightly lower than that of the teeth 6s).

Also in this embodiment, the drain passage d can be easily formed between the spline tooth 6s 'having a low tooth height and the spline groove 1sg on the input shaft 1 side facing the spline tooth 6s'. A similar operation and effect is achieved.
Moreover, in this embodiment, there is an advantage that a decrease in strength of the spline teeth 6s' is suppressed as much as possible, and a spline coupling force is sufficiently ensured.

Although the first and second embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various embodiments are possible within the scope of the present invention. For example, in each of the above embodiments, the height of some of the spline teeth 6s' on the inner rotor 6 side is reduced, but in the present invention, at least some of the spline teeth on the drive shaft (input shaft 1) side are used. The tooth height of 1 s may be reduced, and further, the tooth height of at least a part of the spline teeth of both of them 6 and 1 may be reduced. However, if the spline teeth 6s 'are to be formed low (missing teeth) as in the first embodiment, and the inner rotor 6 is formed, particularly when the inner rotor 6 is formed by sintering, the teeth 6s' are formed. No special machining for lowering (removing teeth) is required, and therefore, spline teeth 1s on the drive shaft (input shaft 1) side
The cost can be reduced as compared with the case where the number of teeth is reduced (missing teeth).

Although the above embodiment has been described as applied to a trochoid pump, the present invention may be applied to other types of high-compression pumps, such as gear pumps. Further, in the above-described embodiment, the oil pump is used for the vehicle belt-type continuously variable transmission T. However, in the present invention, the oil pump may be used for other mechanical devices.

[0025]

As described above, according to the invention of each claim,
Since a drain passage can be easily formed in a part of the spline fitting portion between the drive shaft and the inner rotor, high-pressure oil that inevitably leaks from the side clearance between the rotor and the pump housing passes through the drain passage inside the case. Therefore, it is possible to reliably avoid the problem that the high-pressure leaked oil accumulates in the space between the oil pump and the oil seal and impairs the durability of the oil seal. In addition, there is no need to specially form a high-pressure oil drain passage on the case side, so the structure of the case does not become complicated, and it is necessary to perform special drilling on the case side to form the drain passage. As a result, there is no need to contribute to cost reduction as a whole, and furthermore, no space is required for the drain passage, and the oil seal can be arranged as close to the oil pump as possible, contributing to downsizing of the case in the axial direction. be able to.

According to the second aspect of the present invention, at least one bearing provided between the drive shaft and the case is disposed in the oil passage returning to the internal space of the case via the drain passage. The bearing can be efficiently lubricated by effectively utilizing the leaked oil discharged into the case through the passage.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view (a sectional view taken along line 1-1 in FIG. 2) of a pump according to a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view taken along line 2-2 of FIG. 1;

FIG. 3 is a sectional view similar to FIG. 2, showing a second embodiment of the present invention;

[Explanation of symbols]

 C: a transmission case as a case d: a drain passage P: an oil pump S: an oil seal 1 ... an input shaft as a drive shaft 1s ... a spline tooth 3. ··· Pump housing 5b ··· Opening as one open side 6 ···· Inner rotor 6s, 6s', 6s ″ ··· Spline teeth 11 ··· Side clearance 12 ··· Bearing

Claims (2)

[Claims] 1. A pump housing (3) is provided in a case (C) rotatably supporting a drive shaft (1), and an inner rotor (6) housed in the pump housing (3) includes the drive shaft (3). 1), and an open portion (5) on one axial side of the pump housing (1).
In an oil pump structure in which the space between b) and the drive shaft (1) is sealed by an oil seal (S), at least a part of at least one of the drive shaft (1) and the inner rotor (6) is provided. Spline teeth (6s',
6 "), a drain passage (d) is formed in a part of a spline fitting portion between the drive shaft (1) and the inner rotor (6), and the oil is passed through the drain passage (d). An oil pump structure, wherein an inner portion of the seal (S) communicates with an inner space of the case (C). 2. At least one bearing (12) provided between the drive shaft (1) and the case (C) provides a passage for oil returning from the drain passage (d) to the internal space of the case (C). The oil pump structure according to claim 1, wherein the oil pump structure is arranged.