JP2002195288A - Transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an improved transmission system wherein the operation can be continued even when a vibration-proof elastic member interposed between inner and outer member are peeled and dropped. SOLUTION: The transmission system (an idler gear 1 shown in the form exemplified) where a vibration-proof elastic member 25 is interposed between an inner member 21 supported by a shaft (a fixed shaft 7 shown in the form exemplified) and an outer member 22 through which the driving force is transmitted, comprises an internal gear 23 and an external gear 24, both having the same number of teeth, with the elastic members being interposed in the gap between the inner and outer circumferential surfaces thereof, overlapped with respect to the circumferential direction is made larger than the smallest dimension of the gap in the radial direction. In such a way, the torque exerted between the inner and outer members by tension and compressive loads which act on the elastic member filled in the gap in the circumferential direction of the internal and external gears is arrested.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device, and more particularly to a power transmission device in which an elastic member for vibration isolation is interposed between an inner member and an outer member.

[0002]

2. Description of the Related Art A crank pulley in which an annular rubber layer is provided between an inner pulley member connected to a shaft and an outer pulley member around which a belt is wound to reduce the amount of vibration transmission by this rubber layer is used. It is disclosed in Japanese Patent No. 2527662.

In the above configuration, since the torque transmission between the inner pulley member and the outer pulley member is performed by the shear resistance of the rubber layer, there is a concern that the rubber layer may be peeled off or fall off due to aging or the like. If one rubber layer is peeled off, torque transmission from the inner pulley member to the outer pulley member will not be performed.
The occurrence of such a situation in the crank pulley means that the operation of the engine cannot be continued.

On the other hand, Japanese Patent Publication No. 6-43829 discloses that
The part facing in the radial direction and the part facing in the circumferential direction are provided between the inner member and the outer member, and the part facing in the circumferential direction receives the rotational force to provide between the inner and outer members. There is disclosed a driven reduction gear configured to reduce a shear force acting on a rubber layer. However, even in this case, if the rubber layer peels or falls off and the inner member and the outer member are misaligned or shifted in the axial direction, the operation cannot be continued.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and its main object is to provide a vibration isolator provided between an inner member and an outer member. It is an object of the present invention to provide a power transmission device improved so that the operation can be continued even when the elastic member peels or falls off.

[0006]

In order to achieve the above object, according to the present invention, an inner member (21) supported on a shaft (fixed shaft 7 in the embodiment) and a driving force are transmitted. In a power transmission device (the idler gear 1 in the embodiment) in which a vibration-proof elastic member (25) is interposed between the outer member (22) and the power transmission device (idle gear 1 in the embodiment), the elastic member is provided in a gap between an inner peripheral surface and an outer peripheral surface. Internal gear with the same number of teeth with members interposed (23)
And an external gear (24), and a radial dimension of a portion of the internal gear and the external gear that overlap each other in the circumferential direction is set to be larger than the smallest radial dimension of the gap.

[0007] With this configuration, the rotational torque applied between the inner and outer members by the tensile and compressive loads acting on the elastic member filled in the circumferential gap between the internal gear and the external gear is normally received. Can be Then, even if the elastic member comes off due to deterioration over time or for some reason, the meshing state between the internal gear and the external gear is not released, so that the operation can be continued. In addition, since noise and vibration increase when the elastic member comes off, an abnormality can be immediately perceived.

[0008] In addition to the above configuration, if a means for preventing relative displacement of the inner member and the outer member in the axial direction is provided, even if the elastic member is peeled off, the engagement between the internal gear and the external gear can be prevented. Does not come off.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the accompanying drawings.

FIGS. 1 and 2 show a mounting portion of an idler gear to which the present invention is applied. This idler gear 1
Is provided at an intermediate position of a path for transmitting the rotational force of a crank gear 3 (drive gear) provided on the crankshaft 2 to a pump gear 4 (driven gear) provided on a lubricating oil pump (not shown). The crank gear 3 is formed of a spur gear having the same number of teeth as the crank gear 3, and is engaged with both the crank gear 3 and the pump gear 4 while being attached to an oil pump housing 5 provided in an oil pan.

A fixed shaft receiving hole 6 is formed in the end wall of the oil pump housing 5 in the crankshaft direction. The base end of the fixed shaft 7 is tightly fitted in the fixed shaft receiving hole 6. The fixed shaft 7 has a metal bearing 8 in the shaft insertion hole.
The idler gear 1 is press-fitted and fixed.

At the end of the fixed shaft 7, a retaining flange 9 is provided.
The idler gear 1 is sandwiched between the retaining flange 9 and the oil pump housing 5, and a fixing bolt 10 is fixed to the oil pump housing 5.
Is fixed to the oil pump housing 5 while the idler gear 1 is pivotally supported.

A recess 11 is formed in the bottom surface of the fixed shaft receiving hole 6.
It is formed in a casting process. One of the recesses 11 is concentric with the center of a female screw hole 12 screwed with the fixing bolt 10 and is connected to a gap between the bolt insertion hole 13 of the fixed shaft 7 and the fixing bolt 10. The other part of the concave portion 11 cuts into the inner peripheral surface of the fixed shaft receiving hole 6.
It is connected to the axial groove 14 reaching the opening surface of the fixed shaft receiving hole 6.

A discharge passage 15 for lubricating oil connected to a discharge port of an oil pump (not shown) is connected to the axial groove 14. The discharge path 15 is formed by drilling in an oblique direction from the opening of the fixed shaft receiving hole 6.

A radial through hole 16 is formed at a portion of the fixed shaft 7 which is located at an axially intermediate portion of the metal bearing 8. The radial through hole 16 communicates with a gap between the bolt insertion hole 13 of the fixed shaft 7 and the fixing bolt 10.

The lubricating oil supplied from the discharge passage 15 flows into the axial groove 14, and a part of the oil flows through the axial groove 14 to a sliding contact surface between the axial end face of the idler gear 1 and the oil pump housing 5. The rest flows into the recess 11. Then, the fluid flows out from the concave portion 11 to a sliding contact surface between the fixed shaft 7 and the metal bearing 8 through a gap between the bolt insertion hole 13 of the fixed shaft 7 and the fixing bolt 10 and a radial through hole 16. Further, a radial groove 1 formed on a contact surface of the fixed shaft 7 with the retaining flange 9.
7 flows down the oil pan along the front surface of the idler gear 1.

In this manner, the lubricating oil is sufficiently supplied to the thrust and radial loads of the idler gear 1.

The idler gear 1 includes an inner member 21 pivotally mounted on the fixed shaft 7 and an outer member 22 meshed with the crank gear 3 and the pump gear 4. The inner member 21 and the outer member 22 are meshed with each other with an internal gear 23 and an external gear 24 having the same number of teeth.

The internal gear 23 is, for example, a standard gear having an involute tooth profile.
Is formed by arranging internal teeth facing the outer peripheral contour of the internal gear 23 with an approximately constant width gap on the inner peripheral surface of the perfect circular contour. The gap between the internal gear 23 and the external gear 24 is filled and baked with an elastic member 25 made of an elastomer material having an appropriate hardness.
The vibration transmitted between the inner member 21 and the outer member 22 is absorbed by the elastic member 25. Further, the rotational torque applied between the inner member 21 and the outer member 22 by the tensile and compressive loads acting on the elastic member 25 filled between the tooth surfaces of the internal gear 23 and the external gear 24 is received.

As shown in FIG. 3, the relationship between the internal gear 23 and the external gear 24 is such that the radial dimension B of the portion where the tooth surfaces oppose each other in the circumferential direction is the gap between the two gears 23 and 24. The smallest radial dimension of the
That is, the radial dimension A between the tooth tip surface of the internal gear 23 and the tooth bottom surface of the external gear 24 is made larger (B> A). As a result, even when the elastic member 25 falls off due to aging or the like and a misalignment occurs between the inner member 21 and the outer member 22, at least the engagement between the tooth tips of the internal gear 23 and the external gear 24 is disengaged. Since there is no driving, driving can be continued. In such a state, noise and vibration increase, so that the driver can immediately perceive abnormality.

In particular, the outer member 22 of the idler gear 1
Oil pump housing 5 or cylinder block 2
6 is disposed with a small gap from the axial end face.
Further, the protruding ends of the protruding portions 29 and 30 protruding from the inner surface of the chain case 27 or the oil pan 28 face the outer end surface with a small gap. Thus, the total size of the gaps defined on both surfaces of the outer member 22 is made smaller than the axial length of the idler gear 11. Thus, the axial displacement of the outer members 22 can be prevented from being excessively large when the elastic member 25 is peeled off, so that the engagement between the internal gear 23 and the external gear 24 does not come off.

Here, lubricating oil is supplied through radial grooves 17 between the projections 29 and 30 on the inner surfaces of the chain case 27 and the oil pan 28 and the axial end surfaces of the outer member 22. Therefore, even when the elastic member 25 peels off and the outer member 22 shifts in the axial direction and comes into contact with the protrusions 29 and 30, the protrusions 29 and 30 and the outer member 22 rub against each other. Wear is suppressed.

By the way, between the support portion 31 of the idler gear 1 and the support portion 34 of the pump gear 4 with respect to the oil pump housing 5, and the support portions 31 and 34 of these gears and the oil pump housing 5 are connected to an oil pump body (not shown). ) Are connected by ribs 33 to a plurality of screw bosses 32 for screwing bolts to be fixed thereto.
As a result, the rigidity of the support portions 31 and 34 of the two gears is increased, and the rotation of the two gears 1 and 4 is stabilized, so that it is possible to further reduce the meshing noise of the gears.

The present invention is applicable not only to the above-described gear mechanism but also to a wrapping transmission mechanism such as a pulley or a sprocket.

[0025]

As described above in detail, according to the present invention, the effect of reducing the amount of transmitted vibration and the effect of suppressing noise are not impaired, and the present invention is advantageous in terms of durability as compared with the case of receiving a shear load. In addition, since the function of transmitting the driving force is maintained even if the elastic member provided between the inner and outer members is dropped, a great deal of improvement is required in improving the reliability of this type of vibration isolator. The effect can be achieved. In particular, by providing the relative axial displacement prevention means for the inner and outer members, the axial displacement between the inner and outer members can be suppressed, so that the engagement between the internal gear and the external gear does not come off, This is effective in further improving the maintenance performance of the driving force transmission function.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of an engine having an idler gear to which the present invention is applied.

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a partially enlarged view of an application site of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Idler gear 21 Inner member 22 Outer member 23 Internal gear 24 External gear 25 Elastic member

Claims (2)

[Claims] 1. A power transmission device in which an anti-vibration elastic member is interposed between an inner member supported by a shaft and an outer member to which a driving force is transmitted, the power transmission device comprising: an inner peripheral surface and an outer peripheral surface; The internal gear and the external gear having the same number of teeth with the elastic member interposed in the gap between the internal gear and the external gear, the radial dimension of a part of the internal gear and the external gear that wrap each other in the circumferential direction,
A power transmission device characterized in that it is larger than the smallest radial dimension in the gap. 2. The power transmission device according to claim 1, further comprising means for preventing relative axial displacement between the inner member and the outer member.