JP2001116119A - Reverse idle shaft supporting structure of transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a transmission case by compactly supporting the end of a reverse idle shaft, while avoiding increases in number of part items and man-hours for assembly. SOLUTION: A part of the wall surface of a shaft supporting hole 13e formed in the transmission case 11 is cut so that the shaft supporting hole 13e is formed with a shaft supporting face 13f having a center angle of not less than 180 deg. and an opening 13g having a center angle of less than 180 deg.. When the reverse idle shaft Sr is inserted into the shaft supporting hole 13e, a portion of the outer peripheral surface of the end of the reverse idle shaft Sr is supported by the shaft supporting hole 13e while the remainder of the outer peripheral surface is exposed through the opening 13g to a space within the transmission case 11, so a main shaft Sm contained within the transmission case 11 can be brought as close to the reverse idle shaft Sr as possible to permit miniaturization of the transmission.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reverse idle shaft support structure for a transmission in which a shaft end of a reverse idle shaft is inserted and supported in a shaft support hole formed in a transmission case.

[0002]

2. Description of the Related Art A transmission for an automobile is selectively engaged with a drive gear provided on a main shaft and a driven gear provided on a counter shaft to selectively establish a plurality of forward gears, and is also provided with a reverse idle shaft. The reverse idle gear provided is engaged with a reverse drive gear provided on the main shaft and a reverse driven gear provided on the counter shaft at the same time to establish a reverse gear. Conventionally, the reverse idle shaft is supported on the transmission case by inserting both ends of the reverse idle shaft into a pair of shaft support holes formed in the transmission case.

FIG. 14 shows a conventional example of a support structure for a reverse idle shaft.
Are rotatably supported at both ends of a reverse idle shaft 02, which are inserted into and supported by a pair of shaft support holes 04, 05 of a transmission case 03. To reduce the size of the transmission, the reverse idle shaft 02
To another transmission shaft (for example, main shaft 0
It is desirable to approach 6) as closely as possible. However, the reverse idle shaft 02
When the shaft end of the transmission case 03 is supported by the transmission case 03, the transmission case 0
3 prevents the gear 08 and the synchronization mechanism 09 supported by the main shaft 06 from interfering with the inner wall surface 07 of the transmission case 03 because the inner wall surface 07 of the transmission case 3 protrudes inward. Has to be machined to form the recess 010, which has been a factor in increasing the processing cost.

To avoid this, a shaft end of a reverse idle shaft is supported by a shaft support member, and the shaft support member is fixed to an inner wall surface of a transmission case by bolts, as disclosed in JP-B-63-27212. Is known.

[0005]

[Problems to be Solved by the Invention] By the way, Japanese Patent Publication No.
Japanese Patent Application Laid-Open No. 3-27212 has a problem that a shaft supporting member and a bolt are required to support the shaft end of the reverse idle shaft to the transmission case, and therefore the number of parts and the number of assembling steps increase. is there.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and aims to reduce the size of the transmission case by supporting the shaft end of the reverse idle shaft compactly while avoiding an increase in the number of parts and the number of assembling steps. The purpose is to:

[0007]

According to the first aspect of the present invention, a shaft end of a reverse idle shaft is inserted into a shaft support hole formed in a transmission case to support the shaft. In a reverse idle shaft support structure for a transmission, a part of a wall surface of a shaft support hole is cut out to form a shaft support surface having a central angle of 180 ° or more and an opening having a central angle of less than 180 ° in the shaft support hole. And a part of the outer peripheral surface of the shaft end of the reverse idle shaft is supported by the shaft support surface, and the remaining part of the outer peripheral surface of the shaft end of the reverse idle shaft is passed through the opening to the internal space of the transmission case. A reverse idle shaft support structure for a transmission characterized by being exposed is proposed.

According to the above construction, a part of the wall surface of the shaft support hole formed in the transmission case to support the reverse idle shaft is cut out, and the shaft support hole has one hole.
A shaft support surface having a central angle of 80 ° or more and 180 °
When the shaft supporting surface partially supports the outer peripheral surface of the shaft end of the reverse idle shaft, the remaining portion of the outer peripheral surface of the shaft end of the reverse idle shaft is transmitted through the opening. It is exposed in the internal space of the case. Therefore, the main shaft and the counter shaft housed inside the transmission case are made to approach the reverse idle shaft while avoiding the gears and synchronization mechanisms supported by them to interfere with the inner wall surface near the shaft support hole of the transmission case. Thus, the size of the transmission can be reduced. In addition, since no special member is required to support the reverse idle shaft on the transmission case, it is possible to avoid an increase in the number of parts and the number of assembling steps.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 13 show an embodiment of the present invention. FIG. 1 is a longitudinal sectional view of a manual transmission for a vehicle, FIG. 2 is a diagram showing a change pattern of a change lever, and FIG. FIG. 4 is a cross-sectional view of a main part of the transmission, FIG. 4 is an enlarged view of a main part of FIG. 3 (third-speed / fourth-speed select position), FIG.
(5th speed-reverse select position) corresponding to FIG. 7, FIG. 7 is a diagram corresponding to FIG. 4 (first speed / second speed select position), FIG. 8 is a view in the direction of arrow 8 in FIG. 3, and FIG. Figure 8
, FIG. 10 is an enlarged view of a main part of FIG. 8 (neutral position), FIG. 11 is an operation explanatory view corresponding to FIG. 10 (reverse position), and FIG. 12 is an operation explanatory view corresponding to FIG. (5th speed position), and FIG. 13 is a view taken along line 13-13 of FIG.

As shown in FIG. 1, a transmission case 11 of a manual transmission M for a vehicle having five forward speeds and one reverse speed has a left case half 12 and a right case half divided by a split surface extending in the vehicle longitudinal direction. The shift clutch C is housed in a clutch chamber 14 formed on the side of the left case half 12 on the engine E side. The left and right ends of the main shaft Sm connected to the engine E via the shift clutch C are supported by ball bearings 15, 16 on the left case half 12 and the right case half 13, respectively, and are parallel to the main shaft Sm. Left and right ends of the counter shaft Sc disposed on the left case half 12
And roller bearing 1 on right case half 13 respectively.
7 and ball bearings 18,18. A differential gear D for distributing the output of the counter shaft Sc to the left and right axles 19, 19 is supported by the left case half 12 and the right case half 13 via a pair of left and right ball bearings 20, 21, respectively.

The transmission clutch C housed in the clutch chamber 14 has a clutch wheel 22 connected to the right end of the crankshaft of the engine E and a clutch disk 2 connected to the left end of the main shaft Sm via a damper 23.
The clutch is normally engaged by pressing the facing 27 of the clutch disk 24 between the pressure plate 26 and the clutch wheel 22 by the elastic force of the diaphragm spring 25, and is released by the release fork 28 during shifting. The engagement is released by pressing the bearing 29 to the left.

A main first speed gear 3 is provided on the main shaft Sm.
The first and second speed gears 32 are fixedly provided, and the third third speed gear 33, the fourth speed gear 34, and the fifth fifth speed gear 35 are fixed.
Are supported so as to be relatively rotatable. On the other hand, on the counter shaft Sc, a counter first speed gear 36 and a counter second speed gear 37 meshing with the main first speed gear 31 and the main second speed gear 32, respectively, are rotatably supported. 4th gear 34 and main 5
A counter third speed gear 38 that meshes with each of the high speed gears 35;
A counter fourth gear 39 and a counter fifth gear 40 are fixedly provided.

Left case half 12 and right case half 13
Left and right ends of a reverse idle shaft Sr are supported by the reverse idle shaft Sr. A reverse idle gear 41 slidably supported on the reverse idle shaft Sr can be meshed with a main reverse gear 42 fixed to the main shaft Sm. And can be meshed with a counter reverse gear 43 which is rotatably supported on the counter shaft Sc.

1st speed-2 speed shift fork 44
By moving the sleeve 45 of the speed synchronization mechanism S1 to the left, the first-speed counter gear 36 is coupled to the counter shaft Sc to establish the first-speed gear position, and the first-second speed shift fork 44 synchronizes with the first-second speed gear. By moving the sleeve 45 of the mechanism S1 to the right, the second speed gear 37 is coupled to the counter shaft Sc, and the second speed is established. 3rd speed-
By moving the sleeve 47 of the third-gear / fourth-gear synchronous mechanism S2 leftward with the fourth-gear shift fork 46, the main third gear
The third gear is connected to the main shaft Sm to establish the third speed, and the third-fourth-speed shift fork 46 moves the sleeve 47 of the third-fourth-speed synchronizing mechanism S2 to the right so that the main fourth-speed gear 34 is moved. The fourth speed is established by being coupled to the main shaft Sm.

The fifth-speed shift fork 48 uses a fifth-speed synchronization mechanism S
By moving the third sleeve 49 leftward, the main fifth speed gear 35 is connected to the main shaft Sm, and the fifth speed is established. 5 speed shift fork 48 with 5 speed synchronization mechanism S
When the third sleeve 49 is moved rightward, the reverse shift fork 5 for rotatably holding the reverse idle gear 41 is provided.
0 moves leftward in conjunction with the fifth speed shift fork 48, and the reverse idle gear 41 becomes the main reverse gear 42;
The reverse gear is established by meshing with the counter reverse gear 43 provided on the sleeve 45 of the first-second speed synchronization mechanism S1.

The first-speed / second-speed synchronization mechanism S1, the third-speed / fourth-speed synchronization mechanism S2 and the fifth-speed synchronization mechanism S3 are well known.
The synchronous action is performed by the frictional force of the blocking ring and the synchro cone accompanying the left and right movement of the sleeves 45, 47, 49.

When the first to fifth speeds or the reverse speed is established in this way, the rotation of the counter shaft Sc is transmitted to the differential gear D via the final drive gear 51 and the final driven gear 52, and the left and right axles 19, 19 is driven.

Next, the structure of a change device for establishing the first to fifth gear stages and the reverse gear stage is shown in FIGS.
2 will be described.

FIG. 2 shows an operation pattern of the change lever L of the change device, wherein P1 is a first-speed / second-speed select position, P2 is a third-speed / fourth-select position (neutral position), and P3 is a fifth-speed-reverse. The select position is located on both sides of the first-speed / second-speed select position P1, and is located on both sides of the first-speed position and the second-speed position, the third-speed / fourth-select position P2, and is the third speed, respectively. And R are the fifth speed position and the reverse position, respectively, disposed on both sides of the position and the fourth speed position and the fifth speed-reverse select position P3. An arrow SE in the figure indicates a select operation direction of the change lever L, and an arrow SI in the figure indicates a shift operation direction of the change lever L.

As shown in FIGS. 3 to 5, a dish-shaped recess 13a is formed in the upper portion of the right case half 13 of the transmission case 11, and the recess 13a is formed so as to cover the opening of the recess 13a.
By connecting the cover member 57 with the bolts 56, a breather chamber 58 is defined between the cover member 57 and the recess 13a. A shift select shaft 59 is rotatably and slidably supported in a guide hole 57a formed in the center of the cover member 57 and a guide hole 13b formed in the right case half 13.

A notch 59a is formed at the upper end of the shift select shaft 59 extending from the cover member 57 to the outside via the seal member 60, and the select lever 61 is engaged with the notch 59a. The select lever 61 swings up and down in conjunction with the select operation of the change lever L (the operation in the direction of the arrow SE in FIG. 2), and shifts the shift select shaft 59 to the 3rd-4th select position shown in FIG. −
The 5th-reverse select position moved upward from the 4th-select position (see FIG. 6) and the 1st-second speed select position moved downward from the 3rd- and 4th-select positions (see FIG. 7).
It is movable between and.

Notch 59a of shift select shaft 59
The shift lever 62 is fixed to the lower side of the camera, and rotates left and right in conjunction with the shift operation of the change lever L (the operation in the direction of the arrow SI in FIG. 2). When the change lever L is in the first speed-second speed select position P1,
When the gear is in the third-speed / fourth-select position P2 or the fifth-speed / reverse select position P3, the shift select shaft 5
Reference numeral 9 denotes a neutral position, and when the change lever L is operated to the first speed position, the third speed position, or the fifth speed position, the shift select shaft 59 rotates leftward from the neutral position, and the change lever L moves to the second speed position. 4
When operated to the speed position or the reverse position R, the shift select shaft 59 rotates clockwise from the neutral position. The shift select shaft 59 can be stopped by the detent mechanism 63 (see FIG. 8) at the above three rotational positions with moderation.

A shift arm 64 is fixed to a shift pin 64 on a shift select shaft 59 extending inside the right case half 13.
And the interlock plate 66 is rotatably supported so as to sandwich the shift arm 64 from above and below. The interlock plate 66 has a pair of upper and lower lock claws 66a, 66b. The pair of lock claws 66a, 66b respectively face above and below a driving portion 64a formed at the tip of the shift arm 64. Further, the interlock plate 66 has a guide groove 66c extending in a direction perpendicular to the shift select shaft 59, and the detent pin 67 fixed to the right case half 13 engages with the guide groove 66c.

Therefore, when the shift select shaft 59 moves up and down, the shift arm 64 and the interlock plate 66 move up and down as a unit, but when the shift select shaft 59 rotates, the shift arm 64 rotates together with the shift select shaft 59. On the other hand, the rotation of the interlock plate 66 is restricted by the engagement between the guide groove 66c and the rotation preventing pin 67.

The lower half of the shift select shaft 59 has a small diameter via a stepped first stopper surface 59b formed substantially at the center in the longitudinal direction. The first that slidably fits into
The upper surface of the inner peripheral portion of the spring seat 68 is engaged with the first stopper surface 59b from below, and the upper surface of the outer peripheral portion of the first spring seat 68 is the first lower surface of the cover member 57.
It contacts the support surface 57b. The shift select shaft 59 is disposed below the first spring seat 68.
Disc-shaped second spring seat 6 slidably fitted to
Reference numeral 9 denotes an interlock plate 6
6 and engages with a second stopper surface 66d formed on the upper surface.
A substantially cross-shaped opening 13c is formed in the bottom wall of the concave portion 13a of the right case half 13, and the second spring seat 69 is formed on four stepped second support surfaces 13d formed at the edge of the opening 13c. Is supported on the lower surface of the outer peripheral portion. The upper and lower ends of the select spring 70 are supported between the lower surface of the first spring seat 68 and the upper surface of the second spring seat 69.

When the shift select shaft 59 is at the third-gear / fourth-gear select position shown in FIG. 4, the shift select shaft 59 is slidably supported by the shift select shaft 59 and separated from each other by the select spring 70. Energized first
The inner peripheral upper surface of the spring seat 68 and the inner peripheral lower surface of the second spring seat 69 are formed on the first stopper surface 59a of the shift select shaft 59 and the upper surface of the interlock plate 66, respectively.
d, and the upper surface of the outer peripheral portion of the first spring seat 68 and the lower surface of the outer peripheral portion of the second spring seat 69 are respectively connected to the first support surface 57b of the cover member 57 and the second support surface 13d of the recess 13a. , And the shift select shaft 59 is stably stopped at the third-speed / fourth-speed select position.

From this state, the shift select shaft 59
Is moved upward toward the fifth speed-reverse select position (see FIG. 6), the second spring seat 69 pressed by the second stopper surface 66d of the interlock plate 66 integrated with the shift select shaft 59 releases the cover member 57. Spring seat 68 locked to the first support surface 57b
Is lifted while leaving in the original position, the select spring 70 is compressed, and an urging force is generated to return the shift select shaft 59 to the third- or fourth-speed select position.

Conversely, the shift select shaft 59 is moved from the third-gear / fourth-gear select position to the first-gear / second-gear select position (FIG. 7).
Down) to shift select shaft 5
9, the first spring seat 68 pressed by the first stopper surface 59b is moved down while leaving the second spring seat 69 locked by the second support surface 13d of the opening 13c in the original position. 70 is compressed, and an urging force is generated to return the shift select shaft 59 to the third- or fourth-speed select position.

As described above, since the shift select shaft 59 can be biased to the neutral position, that is, the third-speed / fourth-speed select position and centered by one select spring 70, two shift select shafts 59 are provided. The number of parts and the cost can be reduced as compared with the case where the springs urge upward and downward, respectively. In addition, if two springs are supported on the shift select shaft 59, the shift select shaft 59 is inevitably elongated, but by using only one, the overall length of the shift select shaft 59 can be reduced.

The inner space of the breather chamber 58 defined by the concave portion 13a of the right case half 13 and the cover member 57 is formed by the inner periphery of the opening 13c and the second spring seat 6.
9 communicates with the internal space of the transmission case 11 through four through-holes 71 formed with the outer periphery of the transmission case 9.
The transmission case 1 is connected via a breather tube 73 provided at the end of a breather pipe 72 integrated with the cover member 57.
1 communicates with the external space.

A shift select shaft 59, a first spring seat 68, a second spring seat 69, a select spring 70, a shift arm 64,
The fixing pin 65 and the interlock plate 66 are assembled in advance to form a sub-assembly A, and the sub-assembly A is inserted into the opening 13c from the recess 13a of the right case half 13, and assembled, thereby improving the assembly workability. Can be significantly increased.

The breather chamber 58 is defined by the concave portion 13a of the right case half 13 and the cover member 57.
Since the first spring seat 68, the second spring seat 69, and the select spring 70 are housed inside the breather chamber 58, a common space is formed between the space forming the breather chamber 58 and the first spring seat 6.
8, the transmission case 1 is also used as a space for accommodating the second spring seat 69 and the select spring 70.
This makes it possible to avoid an increase in size and an increase in the number of parts. Moreover, the breather chamber 58 and the mission case 1
The first internal space is formed by four through holes 71 formed between the inner periphery of the opening 13c and the outer periphery of the second spring seat 69.
, And the shift arm 64 and the interlock plate 66 are positioned adjacent to each other below the through holes 71..., So that the labyrinth effect effectively prevents oil from entering the breather chamber 58. be able to.

As shown in FIG. 4 and FIG.
Both ends of a first-speed / second-speed shift rod 76 having a second-speed shift fork 44 and the third-speed / fourth-speed shift fork 46
The two ends of the third-speed / fourth-speed shift rod 77 having the five-speed shift fork 48 and the two ends of the fifth-speed-reverse shift rod 78 having the fifth-speed shift fork 48 are connected to the left case half 12 and the right case half 13. Each is slidably supported. 1st speed-
The second-speed shift rod 76, the third-speed to fourth-speed shift rod 77, and the fifth-speed-reverse shift rod 78 each have one
2nd speed shift piece 79, 3rd speed-4 speed shift piece 8
The 0 and 5 speed-reverse shift pieces 81 are fixed, and the notches 79a, 80a, 81a formed at the tips of the three shift pieces 79, 80, 81, respectively.
Are arranged vertically so as to be able to selectively engage with a driving portion 64a provided at the tip of the shift arm 64.

When the shift select shaft 59 is at the third-gear / fourth-gear select position shown in FIG.
The third-fourth-speed shift piece 80 together with the third-fourth-speed shift piece 80 by rotating the shift select shaft 59 from the neutral position.
It can be driven to the high speed position or the fourth speed position. At this time, the lower locking claw 6 of the interlock plate 66
6b is engaged with the notch 79a of the first-speed / second-speed shift piece 79, and the upper locking claw 66 of the interlock plate 66 is engaged.
By engaging a with the notch 81a of the fifth speed-reverse shift piece 81, malfunction of the first speed-second speed shift piece 79 and the fifth speed-reverse shift piece 81 is prevented.

As shown in FIG. 7, the shift select shaft 59 is moved to the 1st speed-2 position below the 3rd-4th speed select position.
When the shift arm 64 is moved to the speed select position,
Drive section 64a is the notch 7 of the first speed-second speed shift piece 79
9a, the first and second speed shift pieces 79 are moved together with the first and second speed shift pieces 79 by the rotation of the shift select shaft 59.
The speed shift rod 76 can be driven from the neutral position to the first speed position or the second speed position. At this time, the lock pawl 66a on the upper side of the interlock plate 66
By engaging the notch 81a of the speed-reverse shift piece 81 and the notch 80a of the third-fourth-speed shift piece 80, the fifth-reverse shift piece 81 and the third-speed-4
Malfunction of the speed shift piece 80 is prevented.

As shown in FIG. 6, when the shift select shaft 59 is moved to the fifth speed-reverse select position above the third speed-fourth speed select position, the drive part 64a of the shift arm 64 is moved to the fifth speed-reverse position. Shift piece 81
, The fifth-reverse-shift rod 78 together with the fifth-reverse shift piece 81 can be driven from the neutral position to the fifth-speed position or the reverse position by the rotation of the shift select shaft 59. At this time, the lock pawl 66b on the lower side of the interlock plate 66 is notched 79a of the first-second speed-shift piece 79 and notch 80a of the third-speed fourth-speed shift piece 80.
The first and second speed shift pieces 79 and the third and fourth speed shift pieces 80 are prevented from malfunctioning.

As shown in FIG. 8, a detent mechanism is provided to stop the first-speed-second speed shift rod 76 in a modest manner corresponding to the first-speed second-speed select position, the first speed position, and the second speed position. 82 are provided. Further, a detent mechanism 83 is provided to stop the third-speed / fourth-speed shift rod 77 in a modest manner corresponding to the third-speed / fourth-speed select position, the third-speed position, and the fourth-speed position.

As shown in FIGS. 8 to 10, the bracket 85 has two bolts 86, 86 on the inner surface of the right case half 13.
The bracket 85 has a fulcrum pin 87
The reverse shift fork 50 is swingably supported via the. A notch 50a is formed at one end of the reverse shift fork 50 with the fulcrum pin 87 interposed therebetween, and a driven cam surface a for reverse shift and a driven cam for neutral return are formed at the other end. The face b and the driven cam face c for neutral holding are continuously formed. On the other hand, 5-speed reverse shift piece 8
A drive cam surface d for reverse shift that can abut on the driven cam surface a for reverse shift, a driven cam surface b for neutral return, and a driven shaft for neutral holding A neutral return drive cam surface e that can contact the cam surface c is formed continuously.

The tip of an arm 85a extending integrally from a bracket 85 supporting the reverse shift fork 50
A detent mechanism 84 is provided for stopping the speed-reverse shift rod 78 with good moderation corresponding to the fifth speed-reverse select position, the fifth speed position, and the reverse position. As shown in FIG. 9, the detent mechanism 84 includes a detent ball 8 urged by a detent spring 84a.
4b, and the detent ball 84b has three recesses 81 formed in the fifth speed-reverse shift piece 81.
b to 81d (see FIGS. 10 to 12).

When the fifth speed reverse shift piece 81 is at the neutral position as shown in FIG. 10, the reverse shift drive cam surface d of the drive cam portion 88 of the fifth speed reverse shift piece 81 and the neutral return drive are provided. The cam surface e abuts against the reverse shift driven cam surface a and the neutral holding driven cam surface c of the reverse shift fork 50, and the reverse idle gear 41 is at the rightmost neutral position on the reverse idle shaft Sr. It is in contact with the end face 13i of the case half 13. Therefore, even if the reverse idle gear 41 moves leftward away from the end surface 13i of the right case half 13, the neutral return drive cam surface e of the drive cam portion 88 and the neutral holding driven cam of the reverse shift fork 50. The contact with the face c prevents the reverse idle gear 41 from moving leftward.

As shown in FIG. 12, when the fifth speed-reverse shift rod 78 moves leftward from the neutral position to the fifth speed position in order to establish the fifth speed, the fifth gear provided on the fifth speed-reverse shift rod 78 is moved. The fifth speed gear 35 is coupled to the main shaft Sm by the speed shift fork 48 to establish the fifth speed (see FIG. 1). At this time, the drive cam surface e for neutral return of the drive cam portion 88 that operates integrally with the fifth speed-reverse shift rod 78 moves so as to slide along the neutral holding driven cam surface c of the reverse shift fork 50, and Shift fork 50
Remains stopped in the neutral position. Also in this case, even if the reverse idle gear 41 attempts to move to the left so as to move away from the end face 13i of the right case half 13, the driving cam surface e for driving the neutral return of the driving cam portion 88.
The reverse idle gear 41 is brought into contact with the neutral shift driven cam surface c of the reverse shift fork 50
Is prevented from moving to the left.

Even if the fifth speed-reverse shift rod 78 moves rightward from the fifth speed position (see FIG. 11) to the neutral position (see FIG. 10) in order to cancel the establishment of the fifth speed, the driving cam portion 88 is operated. The neutral return drive cam surface e slides along the neutral holding driven cam surface c of the reverse shift fork 50, so that the reverse shift fork 50 remains stopped at the neutral position.

As shown in FIG. 11, when the fifth speed-reverse shift rod 78 moves rightward from the neutral position to the reverse position in order to establish the reverse shift speed, the fifth speed-shift provided on the fifth speed-reverse shift rod 78 is performed. Fork 4
8 moves rightward (see FIG. 1). At the same time, 5
The reverse shift driving cam surface d of the driving cam portion 88 which operates integrally with the speed-reverse shift rod 78 presses the reverse shift driven cam surface a of the reverse shift fork 50, and swings the reverse shift fork 50 counterclockwise. Move. As a result, the reverse shift fork 50 moves the reverse idle gear 41 to the reverse idle shaft Sr.
To the left along the reverse idle gear 41
Meshes with the main reverse gear 42 and the counter reverse gear 43 to establish a reverse gear.

In this state, the left end face of the reverse idle gear 41 abuts against the end face 12b of the left case half 12, and even if the reverse idle gear 41 attempts to move rightward from there, the reverse cam of the drive cam 88 is used. The contact between the drive cam surface d and the reverse shift driven cam surface a of the reverse fork 50 prevents the reverse idle gear 41 from moving rightward.

5th gear to cancel establishment of reverse gear
When the reverse shift rod 78 moves leftward from the reverse position (see FIG. 12) to the neutral position (see FIG. 10), the neutral return drive cam surface e of the drive cam portion 88 moves the neutral return driven cam of the reverse shift fork 50. In order to press the surface b, the reverse shift fork 50 swings clockwise. As a result, the reverse shift fork 50 slides the reverse idle gear 41 rightward along the reverse idle shaft Sr, and the reverse idle gear 41 separates from the main reverse gear 42 and the counter reverse gear 43 to establish the reverse gear. Is released.

As is clear from FIGS. 10 and 13,
The reverse idle shaft Sr has a left end fitted and held in a shaft support hole 12a formed in the left case half 12, and a right end fitted and held in a shaft support hole 13e formed in the right case half 13. Is done. Right case half 1
The inner wall surface of the third shaft support hole 13e is not closed in the circumferential direction, and a part of the inner wall surface is opened in a direction facing the main shaft Sm through a notch. That is, the shaft support surface 13f of the shaft support hole 13e that supports the reverse idle shaft Sr is formed of a positive arc having a circumferential angle of about 250 °, and a part of the outer circumferential surface of the reverse idle shaft Sr has a circumference of about 110 °. Opening 13g consisting of a subarc with a corner
Through to the inner space of the right case half 13. Thus, even if a part of the inner wall surface of the shaft support hole 13e is cut off, the shaft support surface 13
If f has a central angle of 180 ° or more, there is no possibility that the reverse idle shaft Sr will fall out of the shaft support hole 13e.

As shown by a chain line in FIG. 8, when the shaft support hole 13e is formed in a closed bag shape, the right case half 1
3 protrudes inside the transmission case 11, the inner wall surface 13h may interfere with a gear provided on the main shaft Sm, and in order to avoid this, the reverse idle shaft Sr and the main shaft Sm When the distance is increased, there is a problem that the transmission case 11 becomes large. However, by removing a part of the shaft support hole 13e of the reverse idle shaft Sr as in the present embodiment, the reverse idle shaft Sr
The reverse idle shaft Sr is provided without providing a special member for supporting the
Can be made as close as possible to the main shaft Sm to reduce the size of the transmission case 11.

The embodiments of the present invention have been described above. However, various design changes can be made in the present invention without departing from the gist thereof.

For example, in the embodiment, the manual transmission M has been exemplified, but the present invention can be applied to an automatic transmission.

[0051]

As described above, according to the first aspect of the present invention, a part of the wall surface of the shaft support hole formed in the transmission case for supporting the reverse idle shaft is cut out, and the shaft support hole is formed. Since a shaft supporting surface having a central angle of 180 ° or more and an opening having a central angle of less than 180 ° are formed, when the shaft supporting surface partially supports the outer peripheral surface of the shaft end of the reverse idle shaft, the opening Through this, the remaining portion of the outer peripheral surface of the shaft end of the reverse idle shaft is exposed to the internal space of the transmission case. Therefore, the main shaft and the counter shaft housed inside the transmission case are made to approach the reverse idle shaft while avoiding the gears and synchronization mechanisms supported by them to interfere with the inner wall surface near the shaft support hole of the transmission case. Thus, the size of the transmission can be reduced. Moreover, since no special member is required to support the reverse idle shaft on the transmission case, it is possible to avoid an increase in the number of parts and the number of assembling steps.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a manual transmission for a vehicle.

FIG. 2 shows a change pattern of a change lever.

FIG. 3 is a cross-sectional view of a main part of a manual transmission for a vehicle.

FIG. 4 is an enlarged view of a main part of FIG.

FIG. 5 is a sectional view taken along line 5-5 of FIG. 4;

FIG. 6 is an operation explanatory view corresponding to FIG. 4 (5th speed—reverse select position)

FIG. 7 is an operation explanatory view corresponding to FIG. 4 (first speed / second speed select position);

FIG. 8 is a view in the direction of arrows in FIG. 3;

9 is a sectional view taken along line 9-9 in FIG.

10 is an enlarged view of a main part of FIG. 8 (neutral position).

11 is an operation explanatory view corresponding to FIG. 10 (reverse position);

FIG. 12 is an operation explanatory view corresponding to FIG. 10 (5th speed position);

FIG. 13 is a view taken along line 13-13 of FIG. 10;

FIG. 14 is a diagram showing a conventional reverse idle shaft support structure.

[Description of Signs] 11 Transmission case 13e Shaft support hole 13g Opening 13f Shaft support surface Sr Reverse idle shaft

Claims (1)

[Claims] 1. A reverse idle shaft support structure for a transmission in which a shaft end of a reverse idle shaft (Sr) is inserted and supported in a shaft support hole (13e) formed in a transmission case (11). By cutting out a part of the wall surface of (1), a shaft support surface (13f) having a central angle of 180 ° or more and an opening (13g) having a central angle of less than 180 ° are formed in the shaft support hole (13e). The shaft support surface (13f) supports a part of the outer peripheral surface of the shaft end of the reverse idle shaft (Sr), and the outer peripheral surface of the shaft end of the reverse idle shaft (Sr) through the opening (13g). The remainder of the mission case (1
A reverse idle shaft support structure for a transmission, wherein the reverse idle shaft support structure is exposed to the internal space of 1).