JP2022030900A - Torque limit structure and transmission - Google Patents

Abstract

To provide a torque limit structure which can reliably transmit limit torque, and to provide a transmission.SOLUTION: A torque limit structure includes: a shaft having a slide surface along a direction around an axis; a gear which has a fitting hole in which the shaft is fitted, is rotated integrally with the shaft by frictional force occurring between an inner peripheral surface of the fitting hole and the slide surface, and rotates relative to the shaft when receiving torque exceeding a limit value; and a biasing member which biases the gear in a direction such that the inner peripheral surface is pressed against to the slide surface. The shaft has an oil passage for supplying a lubrication oil to the slide surface.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to torque limit structures and transmissions.

For example, in Patent Document 1, a main flywheel rotatably arranged integrally with a drive shaft, a friction ring fixed to the main flywheel, and a sub-wheel arranged so as to rotate integrally with a driven shaft. A torque limit structure is disclosed that comprises an intermediate ring arranged between the flywheel, the secondary flywheel and the friction ring, and a spring ring that urges the friction ring axially through the intermediate ring. There is.

Further, for example, in Patent Document 2, a cylindrical member having a tapered inner peripheral surface, a shaft-shaped member having a tapered outer peripheral surface, and a fastening screwed to the tubular member are fastened. A torque limit structure is disclosed that includes a nut as a member and can adjust the frictional force between the inner peripheral surface of the tubular member and the outer peripheral surface of the shaft-shaped member by tightening the nut.

Japanese Unexamined Patent Publication No. 2004-116780 Japanese Unexamined Patent Publication No. 2008-144811

For example, if the tire slips in a puddle and then the grip is restored, or if the clutch is suddenly engaged, the inertia of the vehicle or engine is suddenly applied, so high torque is applied regardless of the engine torque. It may be in the input state (overload slip state). If the clutch slips, the torque will not reach that high, but for example, the dry clutch has a torque that is several times the engine torque because it has a margin for wear (the allowable transmission torque decreases when it wears) and it is difficult to manage the dynamic friction coefficient. Is transmitted to the transmission via the friction surface. Even with a wet clutch, torque that exceeds the engine torque, if not twice the engine torque, is transmitted to the transmission via the friction surface. As a result, an excessive input torque is applied to each part of the transmission.

By the way, when the transmission does not have a torque limit structure, it is necessary to use a high-strength gear train in order to prepare for an excessive input torque. As a result, there is a problem that the weight of the transmission increases and the size of the transmission increases.

On the other hand, when the transmission has a torque limit structure, when an excessive torque exceeding the limit torque (limit value) is input, the transmission of the excessive torque is cut off while the limit torque is transmitted. By doing so, it becomes possible to protect each part of the transmission.

Since it is difficult to manage the frictional force generated between the friction ring and the intermediate ring in the torque limit structure described in Patent Document 1, the inner circumference of the tubular member is also in the torque limit structure described in Patent Document 2. Since it is difficult to manage the frictional force generated between the surface and the outer peripheral surface of the shaft-shaped member, there is a problem that it is difficult to reliably transmit the limit torque.

An object of the present disclosure is to provide a torque limit structure and a transmission capable of reliably transmitting a limit torque.

In order to achieve the above object, the torque limit structure in the present disclosure is:
A shaft with a sliding surface along the axial direction,
It has a fitting hole that fits into the shaft, and due to the frictional force generated between the inner peripheral surface of the fitting hole and the sliding surface, it rotates integrally with the shaft and receives torque exceeding the limit value. If so, a gear that rotates relative to the shaft and
An urging member that urges the inner peripheral surface in a direction of pressing against the sliding surface, and
Equipped with
The shaft has an oil passage for supplying lubricating oil to the sliding surface.

The transmission in the present disclosure includes the above torque limit structure.

According to the present disclosure, the limit torque can be reliably transmitted.

FIG. 1 is a cross-sectional view illustrating a main part of a transmission having a torque limit structure according to an embodiment of the present disclosure. FIG. 2 is a view taken along the arrow A of FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
FIG. 1 is a cross-sectional view illustrating a main part of a transmission 1 provided with a torque limit structure 100 according to an embodiment of the present disclosure. FIG. 2 is a view taken along the arrow A of FIG.

The X-axis and the Y-axis are drawn in FIG. In FIG. 1, the left-right direction is referred to as an axial direction or an X direction, the right direction is referred to as one end side in the axial direction or "+ X", and the left direction is referred to as the other end side in the axial direction or "-X". Further, in FIG. 1, the direction orthogonal to the axial direction is referred to as the radial direction or the Y direction, the direction away from the axis in the radial direction is the radial outside or “+ Y”, and the direction approaching the axis in the radial direction is the radial inside or “. -Y ".

As shown in FIGS. 1 and 2, the torque limit structure 100 according to the embodiment of the present disclosure is used for the transmission 1.

Although not shown, the transmission 1 includes a case, a main shaft (also referred to as an output shaft) and a counter shaft supported by the case in parallel and rotatably, and a plurality of transmissions supported by the main shaft so as to be idle. Main gear, multiple counter gears supported by the counter shaft so that they always mesh with the main gear, and a sleeve that is axially movable on the main shaft to engage and disengage the corresponding main gear of the multiple main gears. It is provided with an input shaft to which the power of the engine is input and arranged coaxially with the main shaft, and a gear that is rotatably supported by the input shaft and meshes with one of a plurality of counter gears.

The torque limit structure 100 includes a shaft 2, a gear 3, a snap ring 4, an adjust ring 5, and an urging member 6.

The shaft 2 is, here, a counter shaft. The shaft 2 may be, for example, a main shaft or an input shaft. The shaft 2 has a sliding surface 20 along the axial direction.

As shown in FIG. 1, the sliding surface 20 has a convex portion 21 that protrudes radially outward (+ Y direction) from the outer peripheral surface of the shaft 2. The convex portion 21 has an inclined surface 22 that is inclined at a predetermined angle θ with respect to the axial direction (X direction).

FIG. 2 is a view taken along the arrow A of FIG. As shown in FIG. 2, the convex portions 21 are arranged at predetermined intervals in the axial direction. FIG. 2 shows a plurality of (here, eight) convex portions 21. The plurality of convex portions 21 are collectively referred to as a shaft support portion. The shaft support portion has a truncated cone shape in which one end side (+ X direction) in the axial direction is narrowed.

The sliding surface 20 is arranged between the convex portions 21 adjacent to each other in the axial direction, and has a concave portion 23 that is recessed inward in the radial direction (−Y direction) from the convex portion 21. FIG. 2 shows a plurality of (here, eight) recesses 23. Hereinafter, the recess 23 may be referred to as a lubrication groove.

The shaft 2 has an oil passage 24 for supplying lubricating oil to the sliding surface 20. The oil passage 24 extends from one end side in the axial direction (+ X direction) of the shaft 2 to the other end side in the axial direction (-X direction), and has an axial passage 26 through which lubricating oil passes and a radial outer side from the axial passage 26. It has a radial passage 28 extending in the (+ Y direction) and passing lubricating oil from the axial passage 26 to the sliding surface 20.

The outlet 25 of the oil passage 24 is arranged in each of the lubrication grooves 23. The inlet (not shown) of the oil passage 24 is arranged on one end side in the axial direction or the other end side in the axial direction of the shaft 2.

The gear 3 is a counter gear here. The gear 3 may be, for example, a main gear or a gear supported by an input shaft. The gear 3 is pivotally supported by a shaft support portion (a plurality of convex portions 21) so as to be relatively rotatable. The gear 3 has a fitting hole 30 (see FIG. 1) that fits into a shaft support portion (plurality of convex portions 21). The inner peripheral surface 32 (see FIG. 1) of the fitting hole 30 has a conical cylinder shape in which one end side (+ X direction) in the axial direction is narrowed, similar to the truncated cone-shaped shaft support portion.

The snap ring 4 is arranged on one end side (+ X direction) in the axial direction with respect to the gear 3. The snap ring 4 is fitted in an annular groove 29 (see FIG. 1) of the shaft 2. As a result, the snap ring 4 is restrained from moving on one end side (+ X direction) in the axial direction.

The adjust ring 5 is arranged on one end side (+ X direction) in the axial direction with respect to the gear 3 and on the other end side (−X direction) in the axial direction with respect to the snap ring 4. The adjust ring 5 is an annular plate having a predetermined plate thickness, and is externally fitted to the shaft 2. The adjust ring 5 is restrained from moving on one end side (+ X direction) in the axial direction by the snap ring 4.

The urging member 6 is a set spring having an annular shape. The set spring 6 is arranged on one end side (+ X direction) in the axial direction from the end face 34 on one end side (+ X direction) in the axial direction of the gear 3 and on the other end side (−X direction) in the axial direction from the adjust ring 5. Has been done. That is, the set spring 6 is interposed in the axial (X direction) gap between the end surface 34 of the gear 3 and the adjust ring 5.

The inner peripheral side edge portion 62 in the annular shape engages the shaft 2 via the adjust ring 5 and the snap ring 4. As a result, the inner peripheral side edge portion 62 is restrained from moving in the one end side (+ X direction) in the axial direction. The outer peripheral side edge portion 64 in the annular shape abuts on the end surface 34 on one end side (+ X direction) in the axial direction of the gear 3. As described above, the set spring 6 urges the gear 3 toward the other end side (−X direction) in the axial direction by the restoring force.

The urging force of the set spring 6 is increased by narrowing the axial (X direction) gap between the end surface 34 of the gear 3 and the adjust ring 5. On the other hand, the urging force of the set spring 6 is reduced by widening the above-mentioned gap. The set spring 6 urges the gear 3 toward the other end side (−X direction) in the axial direction by the restoring force thereof, so that the inner peripheral surface 32 of the gear 3 is pressed against the inclined surface 22. As a result, a resistance force (hereinafter, frictional force) in a direction that hinders the relative rotation of the shaft 2 and the gear 3 is generated between the inner peripheral surface 32 and the inclined surface 22.

Next, a method of assembling the torque limit structure 100 will be briefly described.
First, the gear 3 is fitted onto the shaft 2 from one end side (+ X direction) in the axial direction. At this time, the inner peripheral surface 32 of the fitting hole 30 is positioned at the position of the inclined surface 22.

Next, the set spring 6 is fitted onto the shaft 2 from one end side in the axial direction. At this time, the set spring 6 is positioned at an axial position between the wall surface 34 of the gear 3 and the annular groove 29 of the shaft 2.

Next, the adjust ring 5 is fitted onto the shaft 2 from one end side in the axial direction. At this time, the adjust ring 5 is positioned at an axial position between the setup spring 6 and the annular groove 29.

Next, the snap ring 4 is fitted onto the shaft 2 from one end side in the axial direction. Then, the snap ring 4 is fitted into the annular groove 29. As a result, the gear 3, the snap ring 4, and the adjust ring 5 can be positioned in the axial direction.

By the above method, each of the gear 3, the snap ring 4, the adjust ring 5 and the set spring 6 can be assembled to the shaft 2 from the same direction (one end side in the axial direction). Further, by fitting the snap ring 4 into the annular groove 29, the gear 3, the snap ring 4, and the adjust ring 5 can be positioned in the axial direction. This makes it possible to easily and accurately assemble the torque limit structure 100.

Next, the adjustment of the frictional force generated between the inner peripheral surface 32 and the inclined surface 22 will be described.
The frictional force can be adjusted by the adjust ring 5. For example, when increasing the frictional force, the plate thickness of the adjust ring 5 may be increased. When the plate thickness of the adjust ring 5 is increased, the axial gap between the end surface 34 of the gear 3 and the adjust string 5 becomes narrower. As a result, the urging force of the set spring 6 interposed in the gap is increased. As a result, the force with which the inner peripheral surface 32 of the gear 3 is pressed against the inclined surface 22 increases, so that the frictional force increases. Since the magnitude of the limit torque is proportional to the magnitude of the frictional force, the limit torque (limit value) becomes large.

On the other hand, for example, when reducing the frictional force, the plate thickness of the adjust ring 5 may be reduced. When the plate thickness of the adjust ring 5 is reduced, the axial gap between the end surface 34 of the gear 3 and the adjust string 5 becomes wider. As a result, the urging force of the urging member 6 interposed in the gap is reduced. As a result, the force with which the inner peripheral surface 32 of the gear 3 is pressed against the inclined surface 22 is reduced, so that the frictional force is reduced. As a result, the limit torque (limit value) becomes small.

Next, the supply of the lubricating oil in the torque limit structure 100 will be described.
The lubricating oil is supplied from the inlet through the axial passage 26, for example, from one end side in the axial direction to the other end side in the axial direction. The lubricating oil supplied to the other end side in the axial direction is supplied from the inside in the radial direction to the outside in the radial direction through the radial passage 28. The lubricating oil supplied to the outside in the radial direction is discharged from the outlet 25. Since the outlet 25 is arranged in the lubricating groove 23, the lubricating oil is supplied to the lubricating groove 23.

Since the lubricating groove 23 is arranged between the inclined surfaces 22 adjacent to each other in the axial direction, the lubricating oil supplied to the lubricating groove 23 is supplied to the inclined surface 22 adjacent to the lubricating groove 23 in the axial direction. .. Further, when the gear 3 rotates relative to the shaft 2, the lubricating oil is easily and surely supplied to the inclined surface 22.

For example, when an excessive torque is input to the gear 3 and the gear 3 rotates relative to the shaft 2, sufficient lubricating oil is supplied to the inclined surface 22, so that the inclined surface 22 is lubricated and cooled. As a result, the frictional force generated between the inner peripheral surface 32 and the inclined surface 22 is stabilized, so that the torque limit can be reliably transmitted from the gear 3 to the shaft 2.

Next, the operation of the torque limit structure 100 will be described.
When the input torque input to the gear 3 does not exceed a predetermined threshold value, the gear 3 rotates integrally with the shaft 2 due to the frictional force generated between the inner peripheral surface 32 and the inclined surface 22.

For example, in the overload slip state, when the input torque input to the gear 3 exceeds the limit torque, the gear 3 reliably transmits the limit torque to the shaft 2. This causes the shaft to rotate. Further, it is possible to prevent an excessive input torque from being applied to each part of the transmission 1.

The torque limit structure 100 according to the above embodiment has a shaft 2 having a sliding surface 20 along the axial direction and a fitting hole 30 that fits into the shaft 2, and has an inner circumference of the fitting hole 30. Due to the frictional force generated between the surface 32 and the sliding surface 20, the gear 3 rotates integrally with the shaft 2, and when a torque exceeding the limit value is received, the gear 3 rotates relative to the shaft 2 and the inside. A set spring 6 for urging the peripheral surface 32 in a direction of pressing against the sliding surface 20 is provided, and the shaft 2 has an oil passage 24 for supplying lubricating oil to the sliding surface 20.

With the above configuration, sufficient lubricating oil is constantly supplied to the sliding surface 20, so that the sliding surface 20 is lubricated and cooled. As a result, the frictional force generated between the inner peripheral surface 32 and the sliding surface 20 is stabilized. As a result, for example, in an overload slip state, even when an excessive torque is input to the gear 3, the torque limit can be reliably transmitted from the gear 3 to the shaft 2.

Further, in the torque limit structure 100 according to the above embodiment, the oil passage 24 extends from one end side in the axial direction of the shaft 2 to the other end side in the axial direction, and has an axial passage 26 for passing lubricating oil and an axial passage. It has a radial passage 28 extending radially outward from 26 and passing lubricating oil from the axial passage 26 to the sliding surface 20. As a result, for example, when a plurality of gears 3 are supported by one shaft 2, the radial passage 28 may extend from the axial passage 26 to a position corresponding to each gear 3 as the oil passage 24. Therefore, with a simple configuration, the lubricating oil can be efficiently supplied to the sliding surface 20.

Further, in the torque limit structure 100 according to the above embodiment, the sliding surfaces 20 are arranged at predetermined intervals in the axial direction, and have an inclined surface 22 (convex portion) protruding outward in the radial direction and an axial rotation. It has a lubrication groove 23 (recess) arranged between the inclined surfaces 22 adjacent to each other in the direction and recessed inward in the radial direction. As a result, the lubricating oil supplied to the sliding surface 20 can be stored in the lubricating groove 23, and the stored lubricating oil can be easily and surely supplied to the inclined surface 22 adjacent to the lubricating groove 23. be able to.

Further, in the torque limit structure 100 according to the above embodiment, the outlet 25 of the oil passage 24 is arranged in the lubrication groove 23 (recess). As a result, the lubricating oil supplied to the sliding surface 20 can be quickly and reliably supplied to the lubricating groove 23.

Further, in the torque limit structure 100 according to the above embodiment, the convex portion 21 has an inclined surface 22 that is inclined with respect to the axial direction (X direction). The set spring 6 urges the gear 3 toward the other end side (-X direction) in the axial direction by the restoring force thereof. As a result, the inner peripheral surface 32 of the gear 3 is pressed against the inclined surface 22. As the inclination angle of the inclined surface 22 decreases, the drag force in the direction orthogonal to the inclined surface 22 with respect to the urging force increases, so that the frictional force generated between the inner peripheral surface 32 and the inclined surface 22 increases. As a result, the limit torque becomes large, so that a large limit torque can be transmitted with a small load (urging force).

Further, in the torque limit structure 100 according to the above embodiment, the inner peripheral side edge portion 62 in the annular shape engages with the shaft 2 via the snap ring 4 and the adjust ring 5. Further, the outer peripheral side edge portion 64 in the annular shape abuts on the end surface 34 on one end side (+ X direction) in the axial direction of the gear 3. As a result, the set spring 6 urges the gear 3 toward the other end side (−X direction) in the axial direction by the restoring force. As described above, by adjusting the plate thickness of the adjust ring 5, the urging force of the set spring 6 is adjusted, and by adjusting the urging force, the frictional force generated between the inner peripheral surface 32 and the inclined surface 22 is adjusted. With a simple configuration, it is possible to adjust the magnitude of the limit torque.

In addition, the above embodiments are merely examples of the embodiment of the present disclosure, and the technical scope of the present disclosure should not be construed in a limited manner by these. .. That is, the present disclosure can be implemented in various forms without departing from its gist or its main characteristics.

The present disclosure is suitably used for a transmission having a torque limit structure that is required to reliably transmit a limit torque even in an overload slip state.

1 Transmission 2 Shaft 3 Gear 4 Snap ring 5 Adjust ring 6 Set spring (urgency member)
20 Sliding surface 21 Convex part 22 Inclined surface 23 Concave part (lubrication groove)
24 Oil passage 25 Outlet 26 Axial passage 28 Radial passage 29 Circular groove 30 Fitting hole 32 Inner peripheral surface 34 End surface 62 Inner peripheral side edge 64 Outer peripheral edge 100 Torque limit structure

Claims (7)

A shaft with a sliding surface along the axial direction,
It has a fitting hole that fits into the shaft, and due to the frictional force generated between the inner peripheral surface of the fitting hole and the sliding surface, it rotates integrally with the shaft and receives torque exceeding the limit value. If so, a gear that rotates relative to the shaft and
An urging member that urges the inner peripheral surface in a direction of pressing against the sliding surface,
Equipped with
The shaft has an oil passage for supplying lubricating oil to the sliding surface.
Torque limit structure. The oil passage extends from one end side in the axial direction of the shaft to the other end side in the axial direction, and extends outward in the axial direction orthogonal to the axial direction from the axial passage through which the lubricating oil passes. It has a radial passage through which the lubricating oil is passed from the axial passage to the sliding surface.
The torque limit structure according to claim 1. The sliding surface is
Convex portions arranged at predetermined intervals in the direction around the axis,
A concave portion arranged between the adjacent convex portions in the axial direction and recessing inward in the radial direction from the convex portion, and a concave portion.
Have,
The torque limit structure according to claim 2. The outlet of the oil passage is arranged in the recess.
The torque limit structure according to claim 3. The convex portion has an inclined surface inclined with respect to the axial direction of the shaft.
The torque limit structure according to claim 3 or 4. A snap ring that is immovably fitted to the shaft in the axial direction,
An adjust ring interposed between the urging member and the snap ring,
Equipped with
The urging member is a set spring having an annular shape and urging the gear in the axial direction by the restoring force thereof.
The inner peripheral side edge portion in the annular shape engages the shaft via the adjust ring and the snap ring.
The outer peripheral side edge portion in the annular shape abuts on the gear.
The torque limit structure according to claim 5. A transmission having the torque limit structure according to any one of claims 1 to 6.

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