JP2005155800A - Gear clash prevention mechanism of reverse shift - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear clash prevention mechanism at the time of reverse shift capable of using parts in common without changing any part in a manual transmission having five or six speeds. <P>SOLUTION: This gear clash prevention mechanism of the reverse shift includes a synchromesh provided on a main shaft or a countershaft and a shift fork operation assembly provided relative to one among a plurality of shift forks and a reverse fork shaft and having a one-way structure in which rotation of the main shaft or the countershaft is stopped by operating the synchromesh by moving one shift fork when shifting a gear shift operation member from a neutral position to a reverse position, but the shift fork is not moved when the gear shift operation member is returned to the neutral position from the reverse position. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a mechanism for preventing gear squeal during reverse shift of a manual transmission for an automobile.

  As for the reverse gear of the manual transmission, there are roughly classified into a constantly meshing type equipped with a synchro mechanism and a selective sliding type in which a reverse idler gear slides and meshes with a reverse drive gear and a reverse driven gear during a reverse shift.

  The selective sliding reverse gear mechanism does not usually have a synchro mechanism, so when the gears try to engage each other immediately after the clutch is disengaged, the gears that cannot be completely stopped due to inertia and the reverse idler gears. An abnormal noise called a gear squeal due to interference due to differential rotation may occur between the two passengers, which may cause discomfort to the occupant.

  In order to prevent gear squeal during reverse shift, in a conventional general manual transmission, a mechanism for braking the main shaft is provided at the end of the main shaft opposite to the speed change clutch. This increases the size of the manual transmission in the direction along the axis of the main shaft.

In order to solve this problem, Japanese Patent Laid-Open No. 2003-14114 discloses that the main shaft can be temporarily braked when the reverse gear is established to prevent the occurrence of gear squeal and the manual transmission in the direction along the axis of the main shaft. A mechanism for preventing gear squeal at the time of reverse shift has been proposed, which has made it possible to make the system more compact.
Japanese Patent Laid-Open No. 2003-14114

  However, in the conventional gear shift prevention mechanism for reverse shift described in the above-mentioned publication, when the gear shift prevention mechanism is to be shared by the 5-speed manual transmission and the 6-speed manual transmission, the reverse shift gear squeal is used. The prevention cam and the interlock member must be remade, and there is a problem that it is difficult to share parts.

  The present invention has been made in view of these points, and an object of the present invention is to provide a reverse shift gear squeal prevention mechanism that can be shared between manual transmissions having different maximum gears. It is.

  According to the present invention, the reverse shift gear squeal prevention mechanism is rotated by the select operation of the shift operation member and the synchro mechanism provided on the main shaft or the counter shaft, and is axially operated by the shift operation of the shift operation member. A shift select shaft provided so as to be movable, a plurality of shift forks for forward gears mounted so as to be rotatable relative to the shift select shaft and movable in the axial direction, and parallel to a direction orthogonal to the shift select shaft A reverse fork shaft that is extended and rotatably attached to the transmission case, and a reverse fork that is fixed to one end of the reverse fork shaft and that is engageable with a reverse idler gear that is rotatably and slidably attached to the reverse shaft. The reverse fork fixed to the other end of the reverse fork shaft When the moving member and the speed change operation member are shifted to the reverse position at the reverse select position, the reverse fork operating member and the reverse fork are rotated by engaging the reverse fork operating member to rotate the reverse idle gear. A reverse piece fixed to the shift select shaft so as to slide and establish a reverse gear, one of the plurality of shift forks and the reverse fork shaft is provided, and a shift operation member is provided from the neutral When shifting to the reverse position, moving the one shift fork to operate the synchro mechanism to stop the rotation of the main shaft or the counter shaft, while the speed change operation member is returned from the reverse position to the neutral position. The one-way structure that does not move the one shift fork Reverse shift gear squeal-preventing mechanism, characterized by comprising a shift fork actuating assembly having a are provided.

  Preferably, the shift fork operating assembly includes a plate member fixed to the one shift fork and extending in a shift select shaft direction, a pin fixed to a tip portion of the plate member, and a cam holder fixed to a reverse fork shaft. And a cam attached to the cam holder so that the plate member can be moved by selectively engaging the pin.

  According to the present invention, since the reverse shift gear squeal prevention mechanism is integrated with the reverse fork assembly including the reverse fork, the reverse fork shaft and the reverse fork operating member, the manual transmission between different manual transmissions, for example, a 5-speed manual transmission and 6 This has the effect that the reverse shift gear squeal prevention mechanism can be shared between high-speed manual transmissions.

  Referring to FIG. 1, there is shown a longitudinal sectional view of a manual transmission suitable for applying the reverse shift gear squeal prevention mechanism of the present invention. The manual transmission includes a main shaft (input shaft) 4 and a counter shaft (output shaft) 6 that are arranged in parallel in the transmission case 2.

  The main shaft 4 is connected to an engine (not shown) via a clutch 8, and the countershaft 6 is connected via a final drive gear 12 and a final driven gear 14 to a differential device 10 that transmits power to the left and right drive wheels of the vehicle. Has been. Since the clutch 8 is a known one, its detailed description is omitted.

  Between the main shaft 4 and the counter shaft 6, as a forward shift stage, the first speed stage G 1, the second speed stage G 2, the third speed stage G 3, the fourth speed stage G 4, the fifth speed stage G 5 and 6, in order from the clutch 8 side. A speed stage G6 is arranged. Further, a reverse gear GR is arranged between the first gear G1 and the second gear G2, and a shift of six forward gears and one reverse gear is performed.

  The first speed stage G1 includes a drive gear 16 fixedly attached to the main shaft 4 and a driven gear 18 rotatably attached to the counter shaft 6, and the drive gear 16 and the driven gear 18 mesh with each other.

  The second speed stage G2 includes a drive gear 20 fixedly attached to the main shaft 4 and a driven gear 22 rotatably attached to the counter shaft 6, and the drive gear 20 and the driven gear 22 mesh with each other.

  The third speed stage G3 includes a drive gear 24 that is rotatably attached to the main shaft 4 and a driven gear 26 that is fixedly attached to the counter shaft 6. The drive gear 24 and the driven gear 26 mesh with each other.

  The fourth speed stage G4 includes a drive gear 28 that is rotatably attached to the main shaft 4 and a driven gear 30 that is fixedly attached to the countershaft 6. The drive gear 28 and the driven gear 30 mesh with each other.

  The fifth speed stage G5 includes a drive gear 32 rotatably attached to the main shaft 4 and a driven gear 34 fixedly attached to the counter shaft 6. The drive gear 32 and the driven gear 34 mesh with each other.

  The sixth speed stage G6 includes a drive gear 33 that is rotatably attached to the main shaft 4 and a driven gear 35 that is fixedly attached to the counter shaft 6. The drive gear 33 and the driven gear 35 mesh with each other.

  Switching of each gear stage is performed by three synchromesh mechanisms 36, 38, and 40. The first synchromesh mechanism 36 is provided on the counter shaft 6 between the first speed driven gear 18 and the second speed driven gear 22.

  The second synchromesh mechanism 38 is provided on the main shaft 4 between the third speed drive gear 24 and the fourth speed drive gear 28. The third synchromesh mechanism 40 is provided on the main shaft 4 between the fifth speed drive gear 32 and the sixth speed drive gear 33.

  Except at the time of a shift change, the power of the main shaft 4 is transmitted to the countershaft 6 through the gear stage selected by the operation of the synchromesh mechanisms 36-40. After being decelerated by the final reduction ratio of the final drive gear 12 and the final driven gear 14, it is transmitted to the differential device 10. As a result, the drive wheel rotates in the forward direction.

  On the other hand, at the time of retreat, first, all the synchromesh mechanisms 36 to 40 are set to the neutral state. The reverse drive gear 42 fixedly attached to the main shaft 4 and the reverse driven gear 44 formed integrally with the shift sleeve 36a of the synchromesh mechanism 36 are not directly meshed with each other but are in a line. Yes.

  In this state, the reverse idler gear 48 rotatably and slidably attached to the reverse shaft 46 is slid in the axial direction on the reverse shaft 46 by the reverse fork 60, and both the reverse drive gear 42 and the reverse driven gear 44 are provided. Mesh with.

  As a result, the power of the main shaft 4 is transmitted to the counter shaft 6 via the reverse drive gear 42, the reverse idler gear 48 and the reverse driven gear 44. During reverse, power is transmitted to the countershaft 6 via the reverse idler gear 48. Therefore, the rotation direction of the countershaft 6 is opposite to that during forward movement, and the drive wheels rotate in the reverse direction.

  In FIG. 1, in order to clarify the structures of the reverse shaft 46 and the reverse idler gear 48, these are shown above the reverse gears 42, 44. Note that it is in a position where it can mesh with both gears 42, 44.

  As shown in FIG. 2, the main shaft 4 and the counter shaft 6 are arranged substantially side by side, and the reverse shaft 46 is arranged substantially below the main shaft 4. A shift select shaft (shift fork shaft) 52 that is linked to a change lever 50 (see FIG. 3) that is a speed change operation member is disposed above the middle portion of the main shaft 4 and the counter shaft 6.

  Referring to FIG. 3, the operation direction of the change lever 50 is shown. That is, the change lever 50 is arranged so as to execute a selection operation in the direction indicated by X and a shift operation in the direction indicated by Y that is orthogonal to the selection operation direction.

  In the select operation direction, a select position P1 for 1-2 speed, a select position P2 for 3-4 speed, a select position P3 for 5-6 speed, and a select position P4 for reverse travel are arranged in a line. Then, the shift lever 50 is moved to either the first speed position D1 that establishes the first speed G1 or the second speed position D2 that establishes the second speed G2 by a shift operation at the select position P1 for the first or second speed. Can do.

  The shift lever 50 can be moved to either the third speed position D3 that establishes the third speed stage G3 or the fourth speed position D4 that establishes the fourth speed stage G4 by a shift operation at the select position P2 for the third to fourth speeds. The change lever 50 can be moved to either the 5th speed position D5 that establishes the 5th speed stage G5 or the 6th speed position D6 that establishes the 6th speed stage G6 by a shift operation at the select position P3 for the 5th to 6th speeds. The change lever 50 can be moved to the reverse position R that establishes the reverse gear GR by a shift operation at the reverse select position P4.

  Referring to FIG. 2 again, the shift select shaft 52 has an axis parallel to the axial direction of the main shaft 4 and the counter shaft 6 which are the displacement directions of the shift forks 54-1, 54-2, 54-3. It is arranged and rotates in conjunction with a select operation of the change lever 50 via an interlocking mechanism (not shown), and moves in the axial direction in conjunction with a shift operation of the change lever 50.

  As shown in FIG. 4, the shift select shaft 52 includes a 1-2 speed shift fork 54-1, a 3-4 speed shift fork 54-2, and a 5-6 speed shift fork 54-3. The collar portion 54a at the end is supported so as to be rotatable with respect to the shift select shaft 52 and movable in the axial direction.

  Here, each shift fork 54-1, 54-2, 54-3 is prevented from rotating by engagement with each shift sleeve 36a, 38a, 40a, but is rotatable with respect to the shift select shaft 52. Therefore, rotation of the shift select shaft 52 is allowed.

  The shift select shaft 52 is positioned between the 1-2 speed shift fork 54-1 and the 3-4 speed shift fork 54-2, and each shift fork 54-1, 54-2, 54-3 is an axis line. A shift piece 56 that is selectively displaced in the direction is fixed at a collar portion 56a at the base end thereof.

  The shift piece 56 rotates around the axis of the shift select shaft 52 in conjunction with the select operation of the change lever 50 (select operation), and moves in the axial direction of the shift select shaft 52 in conjunction with the shift operation of the change lever 50 ( Shift operation).

  Then, the shift piece 56 is selected by the select operation, the select position P1 for 1-2 speed corresponding to each select position of the change lever 50, the select position P2 for 3-4 speed, the select position P3 for 5-6 speed, and It is rotationally displaced to the reverse selection position P4.

  Further, the shift operation at the select position P1 for the 1-2nd speed causes the axial direction to be displaced to either the first speed position D1 or the second speed position D2, and 3 for the shift operation at the select position P2 for the 3rd-4th speed. Axial displacement to either the speed position D3 or the fourth speed position D4, and a shift operation at the selection position P3 for the 5th to 6th speeds causes an axial displacement to either the fifth speed position D5 or the sixth speed position D6. A shift operation at the reverse select position P4 causes an axial displacement to the reverse position R.

  Each shift fork 54-1, 54-2, 54-3 is fixed with an arm portion 54b extending from the collar portion 54a toward the arrangement portion of the shift piece 56. Here, the arm portion 54 b for the 1-2 speed shift fork 54-1 is disposed at a position corresponding to the select position P 1 for the 1-2 speed of the shift piece 56.

  Similarly, the arm portion 54b of the 3-4 speed shift fork 54-2 is disposed at a position corresponding to the select position P2 for the 3-4 speed of the shift piece 56, and the arm portion of the 5-6 speed shift fork 54-3. 54b is arranged at a position corresponding to the select position P3 for the 5-6 speed of the shift piece 56. Each arm portion 54b is formed with an engaging groove 54c with which the shift piece 56 can be engaged.

  When the shift piece 56 is in the select position P1 for the 1-2 speed, the shift piece 56 is engaged with the engagement groove 54c of the arm portion 54b for the 1-2 speed shift fork 54-1, and the shift piece 56 Due to the shifting operation to the first speed position D1 or the second speed position D2, the first to second speed shift fork 54-1 is displaced in the axial direction from the illustrated neutral position, and the shift sleeve of the first synchromesh mechanism 36 due to this displacement. The first speed G1 or the second speed G2 is established by the displacement 36a.

  Similarly, when the shift piece 56 is in the select position P2 for 3-4 speed, the shift piece 56 is engaged with the engagement groove 54c of the arm portion 54b of the 3-4 speed shift fork 54-2, and the shift piece 56 is engaged. 56 is shifted to the third speed position D3 or the fourth speed position D4, the 3-4 speed shift fork 54-2 is displaced in the axial direction from the illustrated neutral position, and the second synchromesh mechanism 38 is shifted by this displacement. The third speed G3 or the fourth speed G4 is established by the displacement of the sleeve 38a.

  When the shift piece 56 is at the select position P3 for 5-6 speed, the shift piece 56 is engaged with the engaging groove 54c of the arm portion 54b for the 5-6 speed shift fork 54-3, and the shift piece 56 is engaged. 56 shifts to the fifth speed position D5 or the sixth speed position D6, the 5-6 speed shift fork 54-3 is displaced in the axial direction from the illustrated neutral position, and the third synchromesh mechanism 40 is shifted by this displacement. The fifth speed stage G5 or the sixth speed stage G6 is established by the displacement of the sleeve 40a.

  A ball plunger 54d is provided in the collar portion 54a of each shift fork 54-1, 54-2, 54-3. The ball plunger 54d cooperates with a recess (not shown) formed on the outer peripheral surface of the shift select shaft 52 to shift the shift arms 54-1, 54-2, 54-3 to the neutral position and each gear position. Detent function that elastically locks in place.

  An interlock member (co-biting prevention member) 58 is provided on the shift select shaft 52 so as to straddle the shift piece 56. The interlock member 58 includes a pair of side plate portions 58 a and 58 b that are disposed on both sides in the axial direction of the shift piece 56 with an axial interval allowing the shift operation of the shift piece 56.

  Then, the both side plates 58a and 58b are spline-engaged with the shift select shaft 52 to prevent the interlock member 58 from rotating around the shift select shaft 52 so as to rotate integrally with the shift piece 56. The interlock member 58 is restrained so as not to move in the axial direction of the shift select shaft 52 as will be described later so as not to move with the shift operation.

  The interlock member 58 can move relative to the shift select shaft 52 in the axial direction, and the shift select shaft 52 can move in the axial direction even if the interlock member 58 is restrained so as not to move in the axial direction. .

  The interlock member 58 is provided with a slit 58c through which the shift piece 56 is inserted, and a pair of lock claws 58d that oppose the engaging end of the shift piece 56 with respect to the arm portion 54b of each shift fork from both sides in the select operation direction. It has been.

  Then, the lock claw 58d is engaged with the engagement groove 54c of the arm portion 54b of the shift fork that is not engaged with the shift piece 56 so that the corresponding shift fork is restrained to the neutral position.

  That is, when the shift piece 56 is at the select position P1 for the 1-2 speed, the lock claw is inserted into the engagement groove 54c of the arm portion 54b of the 3-4 speed shift fork 54-2 and the 5-6 speed shift fork 54-3. 58d is engaged, and the 3-4 speed shift fork 54-2 and the 5-6 speed shift fork 54-3 are restrained at the neutral position.

  Similarly, when the shift piece 56 is in the select position P2 for the 3-4 speed, the engagement groove 54c of the arm portion 54b of the 1-2 speed shift fork 54-1 and the 5-6 speed shift fork 54-3 is formed. The lock claw 58d is engaged, and the 1-2 speed shift fork 54-1 and the 5-6 speed shift fork 54-3 are restrained to the neutral position.

  When the shift piece 56 is at the select position P3 for 5-6 speed, the engagement groove 54c of each arm portion 54b of the 1-2 speed shift fork 56-1 and the 3-4 speed shift fork 54-2 is formed. The locking claw 58d is engaged, and the 1-2 speed shift fork 54-1 and the 3-4 speed shift fork 54-2 are restrained to the neutral position.

  Further, when the shift piece 56 is in the reverse select position P4, each arm portion of the 1-2 speed shift fork 54-1, the 3-4 speed shift fork 54-2 and the 5-6 speed shift fork 54-3. The locking claw 58d is engaged with the engaging groove 54b, and the 1-2 speed shift fork 54-1, the 3-4 speed shift fork 54-2 and the 5-6 speed shift fork 54-3 are restrained to the neutral position. The Therefore, it is possible to prevent the occurrence of co-engagement such that when one of the forward gears is established, the other forward gear is engaged, or when the reverse gear GR is established, the forward gear is engaged.

  The collar portion 56a of the shift piece 56 and one side plate portion 58a of the interlock member 58 are formed with connecting portions 56b and 58e for the interlocking mechanism connected to the change lever 50, respectively.

  By transmitting the shift operation of the change lever 50 to the connecting portion 56b as an axial movement through the interlocking mechanism, the shift select shaft 52 is moved in the axial direction in conjunction with the shift operation, and the change lever 50 is connected to the connecting portion 58e. The shift select shaft 52 is rotated in conjunction with the select operation by transmitting the select operation as a movement in the rotational direction via the interlocking mechanism.

  By the way, it is also conceivable that the reverse fork 60 is supported on the shift select shaft 52 in the same manner as the shift forks 54-1, 54-2, 54-3, and the reverse fork 60 is operated by the shift piece 56.

  However, as shown in FIG. 2, the reverse shaft 46 is disposed on the opposite side of the shift select shaft 52 across the main shaft 4, so that the reverse fork 60 is used to avoid interference with the main shaft 4. The shift select shaft 52 cannot be supported.

  Therefore, a reverse fork shaft 60a that bypasses the main shaft 4 from the shift select shaft 52 side to the reverse shaft 46 side and is parallel to the direction perpendicular to the axis of the shift select shaft 52 is disposed, and the reverse shaft of the reverse fork shaft 60a is arranged. A reverse fork 60 is fixed to an end portion on the 46 side, and a reverse fork operating member 60b is fixed to an end portion of the reverse fork shaft 60a on the shift select shaft 52 side.

  Further, a reverse piece 62 that can be engaged with a recess 60c formed in the reverse fork operating member 60b is fixed to the shift select shaft 52 at the collar portion 62a at the base end, and the reverse piece 62 is selected together with the shift piece 56. The operation and the shift operation are performed.

  That is, in the present embodiment, the reverse piece 62 is configured to be able to directly move the reverse fork shaft 61a, the reverse fork assembly 61 including the reverse fork 60 and the reverse fork operating member 60b fixed to both ends of the reverse fork shaft 60a. Yes.

  When the shift piece 56 is shifted to the reverse position R at the reverse select position P4, the reverse fork 60 is moved from the neutral position shown in FIG. 4 by the reverse piece 62 via the reverse fork operating member 60b and the reverse fork shaft 60a. 5, the reverse idler gear 48 is displaced to the meshing position with respect to the reverse drive gear 42 and the reverse driven gear 44, and the reverse gear GR is established.

  Here, when the reverse piece 62 is engaged with the reverse fork actuating member 60b even at the forward select positions P1 to P3, the reverse gear GR is also established when the forward gear stage is established by the shift operation at each select position. End up.

  Therefore, the reverse fork operating member 60b is arranged on the same plane as the rotational displacement surface of the reverse piece 62 when the shift piece 56 is in the reverse select position P4, and in the select positions other than the reverse select position P4, As shown in FIG. 6, the reverse piece 62 is shifted outward from the outer surface of the reverse fork operating member 60b so as not to engage with the reverse fork operating member 60b.

  Further, the reverse fork shaft 60 a is pivotally supported by a bracket 64 attached to the transmission case 2. The side plate portion 64a adjacent to the inside of the reverse fork operating member 60b of the bracket 64 is positioned at a side edge portion along the shift select shaft 52 and is recessed in a direction perpendicular to the axis of the shift select shaft 52. Is formed.

  One side plate portion 58a of the interlock member 58 is provided with a reverse restricting portion 58f that engages with the engaging groove 64b. Therefore, the interlock member 58 is restrained so as not to move in the axial direction of the shift select shaft 52 by the side plate portion 64 a of the bracket 64.

  When the shift piece 56 is in the reverse select position P4, the reverse restricting portion 58f does not protrude from the outer surface of the side plate portion 64a of the bracket 64 (it is engaged with the engagement groove 64b), but is for forward movement. When in the selected positions P1 to P3, the projection protrudes to the outer surface of the side plate portion 64a of the bracket 64 through the engaging groove 64b.

  Further, the reverse fork operating member 60b is formed with an arm portion 60d that extends to the portion where the engagement groove 64b is formed so as to contact the outer surface of the side plate portion 64a of the bracket 64. Thus, when the shift piece 56 is in the forward select positions P1 to P3, as shown in FIG. 6, the arm portion 60d comes into contact with the reverse regulating portion 58f protruding from the outer surface of the side plate portion 64a, and the reverse fork 60 is A rotational displacement in the direction in which the reverse gear GR is established is prevented.

  Therefore, it is possible to prevent the reverse fork 60 from being moved inadvertently due to vibration or the like when the forward gear is established, and causing the reverse gear GR to be bitten. When the shift piece 56 is in the reverse select position P4, the reverse restricting portion 58f does not protrude from the outer surface of the side plate portion 64a, so the arm portion 60d does not contact the reverse restricting portion 58f, and the reverse gear GR The rotational displacement of the reverse fork 60 in the established direction is allowed.

  As described above, according to the present embodiment, the shift select shaft 52 supports the shift forks 54-1, 54-2, 54-3 for the forward shift stage, the shift piece 56, the interlock member 58, and the reverse piece 62. Therefore, there is no need to separately provide a support shaft for the shift fork, a shift piece 56, and a support shaft for the interlock member 58, thereby reducing the number of parts and reducing the weight and cost of the manual transmission speed change operation mechanism. be able to.

  Further, the reverse piece 62 is fixed to the shift select shaft 52, and the reverse fork assembly 61 including the reverse fork shaft 60a, the reverse fork 60 and the reverse fork operating member 60b is directly moved by the reverse piece 62. Change efficiency can be improved, and the number of parts and the weight can be reduced when making a 5-speed transmission and a 6-speed transmission separately.

  Next, the reverse shift gear squeal prevention mechanism of the present invention will be described in detail with reference to FIGS. The reverse shift gear noise prevention mechanism of the present embodiment includes a shift fork operation assembly 70 provided in association with the 3-4 speed shift fork 54-2 and the reverse fork shaft 60a.

  The shift fork operating assembly 70 rotates the main shaft 4 by moving the 3-4 speed shift fork 54-2 and operating the synchro mechanism 38 when the speed change operating member 50 is shifted from the neutral position to the reverse position. Although it is temporarily stopped, it has a one-way structure in which the 3-4 speed shift fork 54-2 is not moved when the speed change operating member 50 is returned from the reverse position to the neutral position.

  The shift fork actuating assembly 70 is fixed to the 3-4 speed shift fork 54-2 and extends in the direction of the shift select shaft 52, a cam holder 76 fixed to the reverse fork shaft 60a, and attached to the cam holder 76. Included cam (MBS cam) 78.

  A pin 74 is fixed to the tip of the plate member 72. The MBS cam 78 is attached to the cam holder 76 by a shaft 80 and is urged clockwise by a coil spring (not shown).

  Next, with reference to FIGS. 8 to 11, the operation of the gear squeal prevention mechanism during reverse shift according to this embodiment will be described. FIGS. 8A to 9B show the operation when shifting from neutral to reverse, and FIGS. 10A to 11B show the operation when returning from reverse to neutral.

  FIG. 8A shows a state in which the speed change operating member (change lever) 50 is in the reverse neutral position P4. A cam rotation restricting member 82 is fixed to the cam holder 76 and restricts the clockwise rotation of the MBS cam 78.

  When the change lever 50 starts shifting from P4 to the reverse position (reverse), the reverse fork shaft 60a is rotated counterclockwise as indicated by an arrow 84 in FIG. 8B via the reverse piece 62 and the reverse fork operating member 60b. Rotate to.

  As a result, the tip 78 a of the MBS cam 78 engages with the pin 74 and pushes the plate member 72 upward as indicated by an arrow 86. As a result, the 3-4 speed shift fork 54-2 is moved upward along the shift select shaft 52.

  As shown in FIG. 1, since the 3-4 speed shift fork 54-2 is engaged with the sync sleeve 38a of the sync mechanism 38, the sync sleeve 38a is moved by the movement of the 3-4 speed shift fork 54-2. Thus, a synchro ring (synchronizer ring) is pressed against the dog gear via an annular spring (not shown), the main shaft 4 is braked and its rotation is stopped.

  When the change lever 50 is further shifted to the reverse side, as shown in FIG. 9A, the MBS cam 78 has its tip 78a removed from the pin 74 and further rotated counterclockwise. It is lowered as shown. As a result, the synchro sleeve 38a is returned to the neutral position, so that the braking of the main shaft 4 by the synchro mechanism 38 is released.

  When the change lever 50 is completely shifted to the reverse position, the reverse idler gear 48 is pushed by the reverse fork 60 and slides on the reverse shaft 46 as shown in FIG. And meshes with the reverse driven gear 44.

  Since the rotation of the main shaft 4 is stopped by the braking action via the synchro mechanism 38, the differential rotation between the reverse drive gear 42 and the reverse idler gear 48 does not occur when this gear is engaged, which is caused by the differential rotation. Gear noise is effectively prevented.

  Next, the operation for returning from the reverse position to neutral will be described with reference to FIGS. 10 (A) to 11 (B). FIG. 10A shows a state where the change lever 50 is in the reverse position.

  When the operation of returning the change lever 50 to neutral is started from this state, the reverse fork shaft 60a and the MBS cam 78 rotate in the clockwise direction indicated by the arrow 90 as shown in FIG. 78a contacts the pin 74.

  As described above, the MBS cam 78 is attached to the cam holder 76 by being urged clockwise by a coil spring (not shown), and therefore, as shown in FIG. Clockwise rotation is allowed.

  As a result, even if the reverse fork shaft 60a continues to rotate clockwise as indicated by the arrow 90, the MBS cam 78 does not push up the pin 74, and the change lever 50 as shown in FIG. When fully returned to neutral, the MBS cam 78 rotates in the clockwise direction by the urging force of the coil spring as indicated by an arrow 94, and its tip 78 a moves away from the pin 74.

  As described above, the MBS cam 78 instantaneously moves the plate member 72 when shifting from the neutral position to the reverse position, but has a one-way structure that does not move the plate member 72 at all when shifting from the reverse position to the neutral position. It is attached to the cam holder 76 so as to have it.

  Since the reverse shift gear squeal prevention mechanism of the present embodiment described above is integrated with the reverse fork assembly 61 that moves only during the reverse shift, there is no difference between the 5-speed manual transmission and the 6-speed manual transmission, and no mechanism is changed. The gear squeal prevention mechanism can be shared.

  In the above-described embodiment, the example in which the plate member 72 is attached to the 3-4 speed shift fork 54-2 has been described. However, the plate member 72 may be attached to the 5-6 speed shift fork 54-3. The countershaft 6 may be braked by being attached to the second speed shift fork 54-1.

It is a longitudinal cross-sectional view of the manual transmission suitable for applying the gear shift prevention mechanism of the reverse shift which concerns on this invention. It is a figure which shows the positional relationship of each axis | shaft of the manual transmission shown in FIG. It is a figure which shows the operation pattern of a change lever. It is a perspective view of the speed change operation mechanism when the shift piece is in the reverse select position. It is a perspective view of the speed change operation mechanism when the shift piece is shifted to the reverse position. It is a figure which shows the positional relationship of a reverse piece, a reverse fork operation member, and a reverse control member when a shift piece exists in the select position for reverse drive. It is the perspective view which looked at the speed change operation mechanism shown in FIG. 4 from the back side. It is a figure which shows the action | operation of a gear squeal prevention mechanism when a shift operation is carried out from a neutral to a reverse position. It is a figure which shows the continuation of the action | operation of a gear squeal prevention mechanism when the shift operation is performed from the neutral position to the reverse position. It is a figure which shows the action | operation of a gear squeal prevention mechanism when it returns to neutral from a reverse position. It is a figure which shows the continuation of the action | operation of a gear squeal prevention mechanism when it returns to neutral from a reverse position.

Explanation of symbols

4 Main shaft 6 Counter shaft (Output shaft)
8 Clutch G1-G5 Forward shift stage GR Reverse stage 46 Reverse shaft 50 Change lever (shift operation member)
52 Shift Select Shaft 54-1 1-2 Speed Shift Fork 54-2 3-4 Speed Shift Fork 54-3 5 Speed Shift Fork 56 Shift Piece 58 Interlock Member 60 Reverse Fork 62 Reverse Piece 64 Bracket 70 Shift Fork Actuation Assembly 72 Plate member 74 Pin 76 Cam holder 78 MBS cam 82 Cam rotation restricting member

Claims (2)

Reverse shift gear squeal prevention mechanism,
A synchro mechanism provided on the main shaft or the counter shaft;
A shift select shaft that is rotated by a select operation of the speed change operation member and is movable in the axial direction by a shift operation of the speed change operation member;
A plurality of shift forks for forward shift stages attached to the shift select shaft so as to be relatively rotatable and axially movable;
A reverse fork shaft that extends parallel to the direction perpendicular to the shift select shaft and is rotatably attached to the transmission case;
A reverse fork fixed to one end of the reverse fork shaft and engageable with a reverse idler gear rotatably and slidably attached to the reverse shaft;
A reverse fork operating member fixed to the other end of the reverse fork shaft;
When the shift operating member is shifted to the reverse position at the reverse select position, the reverse fork operating member and the reverse fork are rotated by engaging with the reverse fork operating member, and the reverse idle gear is slid. A reverse piece fixed to the shift select shaft so as to establish a stage;
Provided in association with one of the plurality of shift forks and the reverse fork shaft, and when the speed change operation member is shifted from the neutral position to the reverse position, the one shift fork is moved to operate the synchro mechanism. A shift fork operating assembly having a one-way structure that does not move the one shift fork when the speed change operation member is returned to the neutral position from the reverse position while stopping the rotation of the main shaft or the counter shaft.
A reverse shift gear squeal prevention mechanism characterized by comprising:   The shift fork actuating assembly includes a plate member fixed to the one shift fork and extending in the shift select shaft direction, a pin fixed to a tip portion of the plate member, and a cam holder fixed to the reverse fork shaft. And a cam attached to the cam holder to selectively engage the pin and move the plate member. Reverse shift gear squeal prevention mechanism.

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