JP2017106550A - Power transmission device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure capable of suppressing abrasion of a shaft member and an idling gear, in a structure in which the idling gear is fitted to the shaft member not via a needle bearing.SOLUTION: Since spline teeth 82 subjected to crowning in a circumferential direction of the input shaft 12 are formed on a region radially overlapping with a third input gear 32c, of an input shaft 12, a bearing pressure P between an inner peripheral face 84 of the third input gear 32c and the input shaft 12 is lowered, and abrasion and seizure between the third input gear 32c and the input shaft 12 can be suppressed. Further, since the inner peripheral face 84 of the third input gear 32c has a circular shape when viewed from an axial C direction, a gear rattling sound in sliding of the input shaft 12 and the third input gear 32c can be also suppressed.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a power transmission device for a vehicle, and more particularly to a structure provided with an idle gear that can idle on a shaft member.

  2. Description of the Related Art There is known a vehicle power transmission device that includes a shaft member that is configured to be rotationally driven and an idle gear that is fitted on an outer peripheral surface of the shaft member so as to be free to rotate. This is the power transmission device of Patent Document 1. In the power transmission device of Patent Document 1, a structure in which a needle bearing that has been conventionally provided between a shaft member and an idler gear is eliminated is disclosed. Specifically, a structure is disclosed in which spline teeth are formed on the outer peripheral surface of the shaft member, and a lubrication hole is formed to communicate the inner periphery of the shaft member and the spline teeth. When configured as described above, when the shaft member is driven to rotate, the shaft member and the idle gear are slid. At this time, the lubricating oil is supplied from the lubrication hole to loosely rotate with the outer peripheral surface of the shaft member. The needle bearing is eliminated by lubricating between the inner peripheral surface of the gear and the lubricating oil from the lubricating hole.

JP 2010-60064 A Japanese Patent Laid-Open No. 7-83242

  Incidentally, in the structure of Patent Document 1, in the initial state where the rotation of the shaft member is started, the amount of lubricating oil is insufficient, and if the shaft member and the idler gear slide in such a state, the spline of the shaft member The edge of the tooth hits the inner peripheral surface of the idle gear, and the inner peripheral surface of the idle gear and the spline teeth of the shaft member may be worn.

  The present invention has been made in the background of the above circumstances. The object of the present invention is to provide a shaft member and an idle rotation in a structure in which an idle gear is fitted to the shaft member without a needle bearing. An object of the present invention is to provide a structure that can suppress gear wear.

  The subject matter of the first invention is (a) a vehicle power transmission comprising: a shaft member that rotates about an axis; and an idler gear that is fitted to the outer peripheral surface of the shaft member so as to be free-wheeling. (B) Spline teeth chamfered in the circumferential direction of the shaft member are formed on the outer peripheral surface of the shaft member at a position overlapping with the idle gear in the radial direction of the shaft member, (c) The inner peripheral surface of the idle gear has a circular shape when viewed from the direction of the axis of the shaft member.

  According to the vehicle power transmission device of the first aspect of the present invention, spline teeth chamfered in the circumferential direction of the shaft member are formed in a portion overlapping the idle gear of the shaft member in the radial direction. The surface pressure between the peripheral surface and the shaft member is reduced, and wear of the idle gear and the shaft member can be suppressed. Further, since no spline is formed on the inner peripheral surface of the idle gear, it is possible to suppress rattling noise generated during the sliding of the shaft member and the idle gear.

It is a figure which shows the internal structure of the manual transmission of the vehicle to which this invention was applied suitably. It is sectional drawing for demonstrating the structure of the synchromesh mechanism and input gear of FIG. FIG. 3 is a cross-sectional view of a portion where spline teeth of the input shaft of FIG. It is a perspective view for demonstrating the shape of the spline tooth of FIG. It is the calculation result which calculated | required the surface pressure when a spline tooth is crowned, and the surface pressure when a spline tooth is not crowned.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 shows the internal structure of a manual transmission 10 for a vehicle to which the present invention is preferably applied. The manual transmission 10 is configured to be capable of forming a plurality of gear stages (shift stages) by a shift operation by a driver, and outputs rotation input from an engine (not shown) by decelerating or increasing the speed at a predetermined speed ratio γ. This is a parallel two-shaft stepped transmission mechanism (manual transmission).

  The manual transmission 10 is powered by an input shaft 12 connected to an engine via a clutch (not shown) so that power can be transmitted, a counter shaft 14 arranged in parallel to the input shaft 12, and a driving wheel (not shown). And an output shaft 16 connected to be able to transmit.

  The input shaft 12 is rotatably held by bearings 18 and 20, the counter shaft 14 is rotatably held by bearings 22 and 24, and the output shaft 16 is rotatably held by bearings 26 and 28. Has been.

  Between the input shaft 12 and the counter shaft 14, a gear pair (a first gear pair 30a to a fourth gear pair 30d) including a pair of meshing gears is provided. Specifically, a first gear pair 30a, a second gear pair 30b, a third gear pair 30c, and a fourth gear pair 30d are provided in order from the bearing 18 toward the bearing 20 side. Each of these gear pairs 30a to 30d (simply described as the gear pair 30 unless otherwise distinguished) is composed of a helical gear.

  The first gear pair 30a meshes with the first input gear 32a provided integrally with the input shaft 12 and the first input gear 32a, and can freely rotate on the outer peripheral surface of the counter shaft 14 (relatively rotatable). The first counter gear 34a is fitted to the first counter gear 34a. The first counter gear 34a corresponds to the idle gear of the present invention.

  The second gear pair 30b meshes with the second input gear 32b provided integrally with the input shaft 12, and the second input gear 32b, and can freely rotate on the outer peripheral surface of the counter shaft 14 (relatively rotatable). And a second counter gear 34b that is fitted to the second counter gear 34b. The second counter gear 34b corresponds to the idle gear of the present invention.

  The third gear pair 30c meshes with the third input gear 32c fitted to the outer peripheral surface of the input shaft 12 so as to be freely rotatable (relatively rotatable), and the third input gear 32c, and is integrated with the counter shaft 14. The third counter gear 34c is provided. The third input gear 32c corresponds to the idle gear of the present invention.

  The fourth gear pair 30d meshes with the fourth input gear 32d fitted to the outer peripheral surface of the input shaft 12 so as to be freely rotatable (relatively rotatable) and the fourth input gear 32d, and is integrated with the counter shaft 14. And a fourth counter gear 34d. The fourth input gear 32d corresponds to the idle gear of the present invention. When the first input gear 32a to the fourth input gear 32d are not distinguished from each other, they are simply referred to as the input gear 32. When the first counter gear 34a to the fourth counter gear 34d are not distinguished from each other, the counter gear 34 is simply referred to. It describes.

  An output gear pair 36 is provided between the counter shaft 14 and the output shaft 16. The output gear pair 36 includes a counter gear 38 provided integrally with the counter shaft 14 and a final gear 40 meshed with the counter gear 38 and provided integrally with the output shaft 16. The rotation of the counter shaft 14 is transmitted to the output shaft 16 via the output gear pair 36.

  A synchromesh mechanism 42 is provided between the third input gear 32 c and the fourth input gear 32 d in the axial direction of the input shaft 12. The synchromesh mechanism 42 is a synchronous meshing mechanism that rotationally synchronizes the input shaft 12 and the third input gear 32c or the fourth input gear 32d.

  The synchromesh mechanism 42 includes a sleeve 52 that engages with a shift fork (not shown). When the shift fork moves in the axial direction of the input shaft 12, the sleeve 52 is similarly moved in the axial direction of the input shaft 12.

  For example, when the sleeve 52 moves toward the bearing 18 in the axial direction of the input shaft 12, the input shaft 12 and the third input gear 32c are rotationally synchronized, and then the input shaft 12 and the third input gear 32c transmit power. Connected as possible. That is, the input shaft 12 and the counter shaft 14 are connected via the third gear pair 30c so that power can be transmitted. When the sleeve 52 moves toward the bearing 20 in the axial direction of the input shaft 12, the input shaft 12 and the fourth input gear 32d are rotationally synchronized, and then the input shaft 12 and the fourth input gear 32d transmit power. Connected as possible. That is, the input shaft 12 and the counter shaft 14 are connected via the fourth gear pair 30d so that power can be transmitted.

  A synchromesh mechanism 44 is provided between the first counter gear 34 a and the second counter gear 34 b in the axial direction of the counter shaft 14. The synchromesh mechanism 44 is a synchronous meshing mechanism that rotationally synchronizes the counter shaft 14 and the first counter gear 34a or the second counter gear 34b.

  The synchromesh mechanism 44 includes a sleeve 53 that engages with a shift fork (not shown). When the shift fork moves in the axial direction of the counter shaft 14, the sleeve 53 is similarly moved in the axial direction of the counter shaft 14.

  For example, when the sleeve 53 moves toward the bearing 22 in the axial direction of the counter shaft 14, the counter shaft 14 and the first counter gear 34a are rotationally synchronized, and then the counter shaft 14 and the first counter gear 34a transmit power. Connected as possible. That is, the input shaft 12 and the counter shaft 14 are connected via the first gear pair 30a so that power can be transmitted. Further, when the sleeve 53 moves toward the bearing 24 in the axial direction of the counter shaft 14, the counter shaft 14 and the second counter gear 34b are rotationally synchronized, and then the counter shaft 14 and the second counter gear 34b transmit power. Connected as possible. That is, the input shaft and the counter shaft 14 are connected via the second gear pair 30b so that power can be transmitted.

  As described above, when any one of the first gear pair 30a to the fourth gear pair 30d is connected so as to be able to transmit power, a predetermined gear stage (gear stage) corresponding to the gear pair 30 is established. At this time, the gear pairs 30 constituting the other gear pairs are in an idling state. When none of the first gear pair 30a to the fourth gear pair 30d is connected so as to be able to transmit power, all of the first gear pair 30a to the fourth gear pair 30d are in the idling state, and the manual transmission 14 is set to the neutral state. Become.

  FIG. 2 is a cross-sectional view of the synchromesh mechanism 42 and the third input gear 32c. As shown in FIG. 2, the synchromesh mechanism 42 is disposed on the outer peripheral side of the input shaft 12 as a shaft member. The synchromesh mechanism 42 includes a clutch hub 50, a sleeve 52, a gear piece 54, a synchronizer ring 56, a key 58, and a spring 60. Note that the synchromesh mechanism 44 is basically the same structure as the synchromesh mechanism 42, and a description thereof will be omitted.

  The input shaft 12 is disposed so as to penetrate the inside of the synchromesh mechanism 42. A lubricating oil path indicated by a one-dot chain line is formed inside the input shaft 12, and the lubricating oil is supplied from this lubricating oil path to the sliding surface between the input shaft 12 and the third input gear 32c. It has become.

  The clutch hub 50 is formed in an annular shape, and inner peripheral spline teeth 62 are formed on the inner peripheral surface thereof. The inner peripheral spline teeth 62 are spline-fitted with the spline teeth formed on the outer peripheral surface of the input shaft 12, whereby the clutch hub 50 and the input shaft 12 are rotated together. Spline teeth (outer peripheral teeth) parallel to the axis C are formed on the outer peripheral surface of the clutch hub 50. A plurality of key grooves 64 for accommodating the keys 58 are formed at equal angular intervals on the outer periphery of the clutch hub 50.

  The sleeve 52 is disposed on the outer peripheral side of the clutch hub 50 and has a cylindrical shape. On the inner peripheral surface of the sleeve 52, spline teeth 52a (inner peripheral teeth) that are spline-fitted with the spline teeth formed on the outer peripheral surface of the clutch hub are formed. Accordingly, the sleeve 52 is movable in the direction of the axis C with respect to the clutch hub 50 and is not relatively rotatable. On the inner peripheral surface of the sleeve 52, a plurality of concave grooves 66 that fit into the keys 58 are formed at equiangular intervals. An annular groove 68 that fits with a shift fork (not shown) is formed on the outer peripheral surface of the sleeve 52.

  The key 58 is formed in a rectangular parallelepiped shape (piece shape) and is accommodated in a key groove 64 formed in the clutch hub 50. Accordingly, the key 58 is integrally rotated around the axis C together with the clutch hub 50, while being allowed to move in the direction of the axis C. On the side facing the sleeve 52 in the radial direction of the key 58, a projection 70 is formed that engages with the concave groove 66 of the sleeve 52 and projects outward in the radial direction. Further, the key 58 is moved toward the sleeve 52 (radially outer side) by the spring 60 accommodated in the spring accommodating hole 72 formed from the bottom surface of the key groove 64 toward the axis C side (radially inner side). It is energized. Therefore, the sleeve 52 is positioned in the direction of the axis C by engaging the concave groove 66 of the sleeve 52 with the protrusion 70 of the key 58.

  The gear piece 54 is formed in an annular shape, and an inner peripheral portion thereof is spline-fitted to a third input gear 32 c that is fitted on the outer peripheral surface of the input shaft 12 so as to be freely rotatable (relatively rotatable). Yes. Therefore, the gear piece 54 is rotated integrally with the third input gear 32c. Outer peripheral teeth 54a that can be fitted with spline teeth 52a (inner peripheral teeth) formed on the inner peripheral portion of the sleeve 52 on the outer peripheral portion of the gear piece 54 and away from the clutch hub 50 in the axis C direction. Is formed. The outer peripheral teeth 54a are formed in parallel with the axis C, and are dimensioned so that they can be fitted to the spline teeth 52a of the sleeve 52 when the sleeve 52 moves toward the third input gear 32c in the direction of the axis C. A tapered outer peripheral surface 76 is formed on the outer peripheral surface on the hub 50 side in the axis C direction of the gear piece 54 so that the outer diameter decreases as the clutch hub 50 is approached in the axis C direction.

  The synchronizer ring 56 is formed in an annular shape, and outer peripheral teeth 56 a that can be fitted to the spline teeth 52 a of the sleeve 52 are formed on the outer peripheral portion. The outer peripheral teeth 56a are dimensioned so that they can be fitted to the spline teeth 52a when the sleeve 52 moves toward the third input gear 32c in the axis C direction. A tapered inner peripheral surface 78 that is in surface contact with the tapered outer peripheral surface of the gear piece 54 is formed on the inner peripheral side of the synchronizer ring 56. The tapered inner peripheral surface 78 has a larger inner diameter as the distance from the clutch hub 50 increases in the direction of the axis C. The same number of key grooves 80 as the key 58 are formed at the end of the synchronizer ring 56 on the clutch hub 50 side in the axis C direction. In the key 58, the circumferential dimension of the key groove 80 is made larger than the circumferential dimension of the key 58 so that relative rotation in the circumferential direction is allowed with respect to the synchronizer ring 56 by a predetermined rotation angle. .

  In addition, when the key 58 moves to the gear piece 54 side in the axis C direction, the synchronizer ring 56 abuts the end of the key 58 in the axis C direction against the synchronizer ring 56, so that the key 58 causes the gear piece 54 side in the axis C direction. To be pressed.

  In the synchromesh mechanism 42 configured as described above, when an operating force in the direction of the axis C is input to the sleeve 52 and the sleeve 52 is moved toward the third input gear 32c in the direction of the axis C, the key 58 is moved together with the sleeve 52. Moves in the direction of the axis C toward the third input gear 32c. When the end of the key 58 in the axis C direction contacts the synchronizer ring 56, the key 58 presses the synchronizer ring 56 toward the third input gear 32c in the axis C direction. At this time, the tapered inner peripheral surface 78 of the synchronizer ring 56 and the tapered outer peripheral surface 76 of the gear piece 54 are frictionally engaged, whereby the rotational speed difference between the clutch hub 50 and the gear piece 54 gradually decreases.

  When the sleeve 52 further moves in the direction of the axis C, the sleeve 52 moves beyond the protrusion 70 of the key 58, and the spline teeth 52a of the sleeve 52 are pushed between the outer peripheral teeth 56a of the synchronizer ring 56. When the rotation synchronization is completed, the spline teeth 52a of the sleeve 52 are pushed into the outer peripheral teeth 54a of the gear piece 54, and the rotation of the input shaft 12 is transmitted to the third input gear 32c via the synchromesh mechanism 42.

  By the way, the third input gear 32c is fitted to the input shaft 12 so as to be freely rotatable (relatively rotatable). A plurality of spline teeth 82 (outer peripheral teeth) are formed on the outer peripheral surface of the input shaft 12 that contacts the third input gear 32c. FIG. 3 is a cross-sectional view of the portion of the input shaft 12 where the spline teeth 82 are formed cut along a cutting line A. As shown in FIG. 3, a plurality of spline teeth 82 (outer peripheral teeth) protruding outward in the radial direction are periodically formed on the outer peripheral surface of the input shaft 12 in the circumferential direction. Further, the tooth tip (radially outer side) surface of the spline teeth 82 is in direct contact with the inner peripheral surface 84 of the third input gear 32c and is traveling and is connected to the input shaft 12 via the synchromesh mechanism 42. While the 3 input gear 32c is not connected, it slides between the tooth tip surface of the spline tooth 82 and the inner peripheral surface 84 of the third input gear 32c. As shown in FIG. 3, when the third input gear 32 c is viewed from the direction of the axis C of the input shaft 12, the inner peripheral surface 84 is formed in a circular shape. The input shaft 12 corresponds to the shaft member of the present invention, and the third input gear 32c corresponds to the idle gear of the present invention.

  Accordingly, the sliding surface between the tooth tip surface of the spline tooth 82 and the inner peripheral surface 84 of the third input gear 32c is likely to wear, and seizure may occur between the sliding surfaces. In particular, the above problem is likely to occur immediately after the vehicle starts because the lubricating oil supplied to the sliding surface tends to be insufficient. The seizure occurs when the product (= P × V) of the surface pressure P between the sliding surfaces and the peripheral speed V (relative speed between the sliding surfaces) on the sliding surface increases. Since it is difficult to reduce the speed V, a mechanism for reducing the surface pressure P is proposed in this embodiment. FIG. 4 is a perspective view for explaining the shape of the outer peripheral teeth 82. As shown in FIG. 4, the outer peripheral teeth 82 are subjected to crowning on both sides in the circumferential direction, so that a single curved surface R is formed on both circumferential sides on the radially outer side of the outer peripheral teeth 82. By forming such a curved surface R, the surface pressure P is greatly reduced. The crowning process is continuous as the tooth thickness is directed toward the tooth tip (radially outward) so that bulges are formed over the entire width of the teeth on both ends of the outer peripheral teeth 82 in the circumferential direction. It is processed so as to be gradually reduced, and is usually a kind of chamfering performed by a polishing apparatus.

  FIG. 5 shows calculation results obtained analytically for the surface pressure P when the outer peripheral teeth 82 are crowned and the surface pressure P when the outer teeth 82 are not subjected to crowning as a comparison target. The X axis indicates the position in the circumferential direction (tooth thickness direction) of the surface (sliding contact surface) that is in sliding contact with the input shaft 12 of the outer peripheral teeth 82, and the Y axis is the tooth width direction of the outer peripheral teeth 82 (axis C direction in FIG. 2). The Z-axis indicates the surface pressure P at that position. FIG. 5A shows the surface pressure P when the crowning process is performed according to the present embodiment, and FIG. 5B shows the surface pressure P when the crowning process is not performed.

  As shown in FIG. 5 (a), the surface pressure P is slightly increased at both ends in the circumferential direction (tooth thickness direction) on the sliding contact surface when the outer peripheral teeth 82 of this embodiment are subjected to crowning. However, the value is small, and the surface pressure P is a low value as the whole sliding contact surface. On the other hand, when the crowning process shown in FIG. 5 (b) is not performed, the curved surfaces R are not formed at both ends of the outer peripheral teeth, but the sharp edges are formed. When such sharp edges are formed at both ends of the outer peripheral teeth, the surface pressure P at both ends is very high. Therefore, since the surface pressure P is increased at both ends of the outer peripheral teeth, wear and seizure are likely to occur. On the other hand, in the present embodiment, the surface pressure P is significantly reduced by performing the crowning process, and therefore, wear and seizure on the sliding surface are suppressed.

  Here, in FIG. 2 to FIG. 5, the outer peripheral teeth 82 in which the outer peripheral surface of the input shaft 12 is crowned between the input shaft 12 and the third input gear 32 c are described. The part where the fourth counter shaft 32d of the input shaft 12 is fitted, the part where the first counter gear 34a of the counter shaft 14 is fitted, and the part where the second counter gear 34b of the counter shaft 14 is fitted. Similarly, a spline tooth that is subjected to crowning is formed. Therefore, wear and seizure are also suppressed on these sliding surfaces. The fourth input gear 32d, the first counter gear 34a, and the second counter gear 34b correspond to the idle gear of the present invention, and the counter shaft 14 corresponds to the shaft member of the present invention.

  As described above, according to the present embodiment, the spline teeth 82 that are crowned in the circumferential direction of the input shaft 12 are formed at portions that overlap the third input gear 32 c of the input shaft 12 in the radial direction. The surface pressure P between the inner peripheral surface 84 of the third input gear 32c and the input shaft 12 is reduced, and wear and seizure between the third input gear 32c and the input shaft 12 can be suppressed. Therefore, a bearing conventionally provided between the input shaft 12 and the third input gear 32c can be omitted. As a result, the number of parts and the manufacturing cost can be reduced. Further, the inner peripheral surface 84 of the third input gear 32c has a circular shape when viewed from the direction of the axis C, that is, no spline is formed on the inner peripheral surface 84, so that the input shaft 12 and the third input gear 32c. It is also possible to suppress rattling noise during sliding.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the input shaft 12 and the third input gear 32c can be connected and disconnected via the synchromesh mechanism 42, and the third input gear 32c is connected to the input shaft 12 when the synchromesh mechanism 42 is in a disconnected state. However, the present invention is not limited to the structure provided with the synchromesh mechanism 42, and the structure provided with the idler gear fitted to the shaft member so as to be freely rotatable. If so, it can be applied as appropriate.

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

12: Input shaft (shaft member)
14: Counter shaft (shaft member)
32c, 32d: third and fourth input gears (idling gears)
34a, 34b: first and second counter gears (idling gears)
82: Spline teeth 84: Inner peripheral surface (inner peripheral surface of idle gear)

Claims (1)

A vehicle power transmission device comprising: a shaft member that rotates about an axis; and an idle gear that is fitted to the outer peripheral surface of the shaft member so as to be free to rotate.
Spline teeth chamfered in the circumferential direction of the shaft member are formed on the outer circumferential surface of the shaft member at a position overlapping the idle gear in the radial direction of the shaft member,
The vehicle power transmission device, wherein an inner peripheral surface of the idle gear has a circular shape when viewed from the direction of the axis of the shaft member.

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