JPH07127738A - Electronic control transmission - Google Patents

Abstract

PURPOSE:To provide an electronic control transmission capable of improving durability of a synchronizer, a shift mechanism, etc., and softening transmission shock. CONSTITUTION:The shift drum 80 of a shift mechanism for switching a transmission gear mechanism of an electronic control transmission is slightly movably supported in axial direction, and annular rubber members 115, 117 and needle bearings 114, 116 are mounted respectively, on both front and rear end sides of the shift drum 80, and excessive shifting force is softened by the rubber members 115, 117 when the excessive shifting force is actuated on a shift change transmission system which reaches the synchronizer from the shift drum 80 via shift rods 71-73 and a shift fork. The shift drum 80 is elastically energized by a torsional spring 118 toward shiftup rotational direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronically controlled transmission, and more particularly to an electronically controlled transmission having improved durability of a synchronizing device and a shift mechanism.

[0002]

2. Description of the Related Art Conventional manual transmissions for automobiles are usually constructed such that each shift rod is connected to a shift lever and the shift lever is operated to shift gears. As described in Japanese Patent Laid-Open No. 64-46049, a shift drum and an electric actuator for rotating and driving the shift drum are provided, and a shift groove corresponding to each shift rod is formed on the outer peripheral surface of the shift drum. An electronic device configured to shift gears through the shift rods by engaging the engaging portion at the base end of each shift rod with the corresponding shift groove and rotating the shift drum in response to the operation of the shift lever. Controlled transmissions have been proposed.

Here, in the conventional electronically controlled transmission, the shift force transmission system, which goes through the shift drum, the shift rod, and the shift fork to the synchronizing device, is provided with any mechanism for buffering the shift force. Absent.

[0004]

By the way, at the time of a shift change, the shift drum is rotated at a high speed to move the shift rod in the axial direction to perform the shift change. The transmitted shift force becomes considerably large, and a considerably large shift force acts on the synchronizer and the shift mechanism of the transmission gear mechanism. Moreover, due to the bent portion of the shift groove of the shift drum, manufacturing error of the shift mechanism, thermal expansion or contraction of the shift rod, and rotation of the counter shaft or main shaft of the transmission gear mechanism. Excessive shift force may occur due to the resistance of the synchronizer depending on the condition.

In the conventional electronically controlled transmission, since no mechanism for buffering the shift force is provided in the shift force transmission system, the shift force is directly transmitted from the shift drum to the synchronizing device via the shift rod. Therefore, there is a possibility that an excessive shift force acts on the synchronizer. In particular, since the shift change in the middle speed stage is executed at a high speed, a large shift force is applied, which deteriorates the durability of the synchronizer, especially its synchronizer ring, the shift mechanism, etc., and causes a large shift shock. There's a problem. An object of the present invention is to provide an electronically controlled transmission that can improve the durability of a synchronizing device, a shift mechanism and the like and can alleviate a shift shock.

[0006]

According to another aspect of the present invention, there is provided an electronically controlled transmission in which a transmission gear mechanism of a driving force transmission system of a vehicle is provided with a plurality of shift rods and a shift drum for axially driving the shift rods. In an electronically controlled transmission configured to switch gears, at least one of the shift drum, the shift rod, and a shift fork fixed to the shift rod is provided with a cushioning means for cushioning a shift force. Is.

Here, the buffering means is composed of an elastic member which elastically permits the axial movement of the shift drum (claim 2 dependent on claim 1), and the buffering means is the axial direction of the shift rod. A configuration in which the shift force is buffered through a change in length (claim 3 dependent on claim 1), and the buffer means is elastically deformed in a direction orthogonal to the axis of the shift rod to shift the shift force. A structure for buffering (claim 4 dependent on claim 1),

A structure in which the buffer means buffers the shift force through elastic deformation of the shift fork (claim 5 dependent on claim 1), and the buffer means is an elastic member incorporated in a shift rod. (Claim 6 dependent on Claim 3), the damping means is an oil damper incorporated in the shift rod (Claim 7 dependent on Claim 3), the damping means is on the shift rod. A structure including a load limiter that is incorporated and blocks transmission of a shift force of a predetermined value or more (claim 8 dependent on claim 3),

The buffer means has a configuration in which the cross-sectional shape of the shift rod is elliptical (claim 9 dependent on claim 4), and the buffer means has a configuration in which the cross-sectional shape of the shift rod is rectangular. And the like (Claim 10 dependent on Claim 4), the cushioning means having a structure in which a middle portion of the shift rod is partially cut out (Claim 11 dependent on Claim 4), and the like. It can be configured in the form of.

An electronically controlled transmission according to a twelfth aspect of the present invention is characterized in that a transmission gear mechanism of a driving force transmission system of a vehicle is provided with a plurality of shift rods.
In the electronically controlled transmission configured so that these shift rods are switched via a shift drum that drives in the axial direction, the plurality of shift rods are configured to have different diameters for each shift speed. Here, the shift rod for the medium speed stage can be configured in a mode in which it has a smaller diameter than the shift rods for the other shift stages (claim 13 dependent on claim 12).

[0011]

In the electronically controlled transmission according to the first aspect of the present invention, at least one of the shift drum, the shift rod, and the shift fork fixed to the shift rod is provided with buffer means for buffering the shift force. Since it is provided, it is possible to prevent the shift device including the shift gear mechanism, the shift mechanism including the shift drum, the shift rod, and the shift fork from being applied with an excessive shift force, and to enhance the durability of the synchronizer and the shift mechanism. Also, the shift shock can be alleviated because the shift is not forcibly changed by an excessive shift force.

In the second aspect, since the buffer means is made of an elastic member that elastically allows the shift drum to move in the axial direction, the shift force can be buffered with a simple structure. According to the third aspect, since the buffering means buffers the shift force through the change in the axial length of the shift rod, the buffering means can be provided around the shift rod with a sufficient space. According to the fourth aspect, since the buffering means buffers the shift force through elastic deformation of the shift rod in the direction orthogonal to the axis, the buffering means has a simple structure and is durable.

According to the present invention, since the buffer means buffers the shift force through the elastic deformation of the shift fork, it is possible to reliably prevent an excessive shift force from acting on the synchronizing device. In the sixth aspect, since the cushioning means is made of the elastic member incorporated in the shift rod, the cushioning means has a simple structure and is excellent in cushioning action. In claim 7, since the buffer means is an oil damper incorporated in the shift rod,
Excellent cushioning effect is obtained. In the eighth aspect, since the buffer means is a load limiter that is incorporated in the shift rod and blocks the transmission of the shift force of a predetermined value or more, an excellent buffer action is obtained.

In the ninth aspect, since the buffer means has a configuration in which the cross-sectional shape of the shift rod is elliptical, the structure of the buffer means is simplified. According to the tenth aspect of the present invention, since the buffer means has a configuration in which the cross-sectional shape of the shift rod is rectangular,
The structure of the buffer means is simplified. According to the eleventh aspect, since the buffering means has a structure in which a middle portion of the shift rod is partially cut out, the structure of the buffering means is simplified.

In the electronically controlled transmission according to claim 12,
In an electronically controlled transmission configured to switch a transmission gear mechanism of a drive force transmission system of a vehicle through a plurality of shift rods and a shift drum that axially drives the shift rods, a plurality of shift rods are provided. Since each shift gear has a different diameter, the diameter of each shift rod corresponds to the shift force acting on the shift rod, and the shift force acting on the synchronizer of the transmission gear mechanism can be prevented from becoming excessive. By configuring it with a large diameter, it is possible to suppress the excessive shift force that acts on the synchronizing device and the shift mechanism including the shift drum, the shift rod, and the shift fork, and to enhance their durability. The gear shift shock can also be alleviated because is not applied. According to the thirteenth aspect, by configuring the shift rod for the middle speed stage to have a smaller diameter than the shift rods for the other speed stages, the synchronizing device and the shift mechanism can be operated with a large shift force at the time of a shift change in the middle speed stage. It is possible to prevent deterioration of durability of the.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is an example in which the present invention is applied to an electronically controlled transmission provided in a driving force transmission system of a rear-wheel-drive vehicle for riding. Although this transmission is arranged in the front-rear direction of the vehicle body, the front-rear and left-right directions of the vehicle body of the automobile will be defined as front-rear left-right. As shown in FIGS. 1 to 3, the transmission TM is provided with a clutch mechanism 10, a speed change gear mechanism 40, a shift mechanism 70 for performing a speed change operation of the speed change gear mechanism 40, and the like. By controlling the driving of the shift mechanism 70 and the shift mechanism 70,
A hydraulic system and a control system, which will be described later, for controlling 0 are also provided.

The clutch mechanism 10 is, as shown in FIG. 1, a flywheel 11 connected to an output shaft of an engine.
Is the same as a general pull-type clutch mechanism for connecting and disconnecting the input shaft 12 of the transmission TM with the manual operation force input mechanism operatively connected to the clutch pedal as the operation force input mechanism. In addition to 13, it is unique in that it has an automatic operation force input mechanism 14. In the clutch mechanism 10, the clutch disc 15, the pressure plate 16, the diaphragm spring 17, the release bearing 18, etc. are the same as those of the existing clutch.

In the manual operation force input mechanism 13, a clutch cylinder 20 operatively connected to a clutch pedal via a hydraulic system is attached to a rear wall portion of a left side portion of a casing 19 of the clutch mechanism 10. The output rod 23 is engaged with the release bearing 18 via the first release fork 21, and when the clutch pedal is depressed, hydraulic pressure is supplied to the clutch cylinder 20 and the output rod 23 moves forward to move the release bearing 18
Is pushed rearward, and the clutch mechanism 10 is disengaged.

In the automatic operation force input mechanism 14, a hydraulic actuator 25 composed of a hydraulic cylinder is attached to the rear wall of the right side portion of the casing 19, and its output rod 27 is released via a second release fork 28. An electromagnetic control valve 26, which is engaged with the bearing 18 and has a plurality of solenoid valves 26a for switching oil passages, is provided in the hydraulic actuator 25. When hydraulic pressure is supplied to the hydraulic actuator 25, the output rod 27 advances. By moving, the release bearing 18 is pushed rearward, and the clutch mechanism 10 is disengaged. Incidentally, it goes without saying that a push type clutch mechanism can be applied instead of the pull type clutch mechanism 10 described above.

Next, the transmission gear mechanism 40 will be described. As shown in FIGS. 1 and 2, the speed change gear mechanism 40 has the same structure as a general manual speed change gear mechanism capable of switching between the first to fifth speed shift stages and the reverse speed. To do. In this gear shift mechanism 40,
The casing includes a box-shaped first case member 41 and a tubular second case member 41.
It is composed of a case member 42, a wall-shaped third case member 43, a box-shaped fourth case member 44, and the like. In the casing, the main shaft 45 and the counter shaft 46 are vertically spaced by a predetermined distance so that their axial centers are parallel to each other (that is, the axial center of the main shaft 45 and the counter shaft 46).
Is arranged such that the surface including the axis center of is vertical. The input gear 47 formed on the input shaft 12 meshes with the input gear 48 at the front end of the counter shaft 46.

The counter shaft 46 has an input gear 48, a third speed gear 53, and a second speed gear 5 which are sequentially provided from the front side.
2, a gear train 50 including a first speed gear 51, a reverse gear 49, and a fifth speed gear 55 is provided, and a main shaft 45 is provided with a free-moving 3 gear corresponding to the gears 53, 52, 51, 49, 55, respectively. High speed gear 63, second speed gear 62, first speed gear 61,
A gear train 60 including a reverse gear 66 and a fifth gear 65 is provided. Further, the main shaft 45 has a fourth speed / 3.
A first synchronizer 67 for speed changeover, a second synchronizer 68 for changeover between first speed and first speed, and a third synchronizer 69 for changeover between reverse and fifth speed are provided.

When the first synchronizer 67 is switched to the front position, the fourth speed is achieved in which the rotation is directly transmitted from the input shaft 12 to the main shaft 45, and when it is switched to the rear position, the third speed is achieved.
When the second synchronizer 68 is switched to the front position, the second speed is established, and when it is switched to the rear position, the first speed is established. Third synchronizer 6
When 9 is switched to the front position, the rotation of the reverse gear 49
Reverse is transmitted to the main shaft 45 via the gear of the reverse shaft and the reverse gear 66, and if it is switched to the rear position, the fifth speed is achieved.

Next, the first to third synchronizers 67 to 69
The shift mechanism 70 for switching between will be described (see FIGS. 1 to 4). The shift mechanism 70 includes first to third shift rods 71, 72, 73 for switching the first to third synchronizers 67 to 69, respectively, and shift grooves 81 corresponding to the three shift rods 71 to 73, respectively. A shift drum 80 having shift grooves 81, 82, 83, which are recessed on the outer peripheral surface, and a rack and pinion mechanism 90 for rotationally driving the shift drum 80 in the forward and reverse directions. There is.

The shift drum 80 includes a gear train 60 of the main shaft 45 and a gear train 5 of the counter shaft 46.
A portion that is largely offset axially rearward from 0 and is near the upper end of the rear end side portion of the transmission TM, in parallel with the main shaft 45 and the counter shaft 46, and
It is arranged directly above the main shaft 45 with a predetermined distance from the main shaft 45. The shift drum 80 has a slightly large-diameter drum body portion 84 and shaft portions 85 and 86 integrally extending from both front and rear ends thereof, and the third case member 43 of the casing and the third case member 43 via the shaft portions 85 and 86. The fourth case member 44 is rotatably supported by the fourth case member 44.
A drum cover portion 44a that is close to the upper portion of the shift drum 80 and covers the upper portion is formed.

First to third shift rods 71, 72, 73
Is arranged in the front-rear direction by passing through the wall portion of the casing so as to be movable a predetermined distance in the front-rear direction.
The shift forks 74, 75, 76 fixed to the third shift rods 71, 72, 73 are engaged with the outer peripheral grooves of the sleeves of the first to third synchronizers 67, 68, 69, respectively, so as to be relatively rotatable. There is. The shift groove 8 is provided on the drum body 84.
Three cylindrical bodies 8 are provided so as to cover the outer peripheral sides of 1, 82 and 83, respectively.
7, 88, 89 are fitted to each other so as to be rotatable relative to each other.
Rollers 71 attached to the insides of 88 and 89 in a protruding manner, respectively.
a, 72a, 73a (see FIG. 4) are shift grooves 81, 8
2, 83 are slidably engaged with the cylindrical bodies 87, 88,
89 are fixed to the base end portions of the first to third shift rods 71, 72, 73 via the arm members 77, respectively.

In FIG. 4, three shift grooves 81, 82, 8 are provided.
The development view of No. 3 is shown, and when the roller 71a of the first shift rod 71 is in the fourth speed position P4, it is switched to the fourth speed, and when it is in the third speed position P3, it is switched to the third speed. Second shift rod 7
When the 2nd roller 72a reaches the 2nd speed position P2,
When it reaches the speed position P1, it is switched to the 1st speed. When the roller 73a of the third shift rod 73 reaches the fifth speed position P5, it is switched to the fifth speed, and when it reaches the reverse position PR, it is switched to the reverse position. The shift groove 83 is divided between the fifth speed position P5 and the reverse position PR in order to prevent switching from the fifth speed to reverse due to a malfunction, and the shift groove 83 is separated at a position corresponding to the divided position. 81 and 82 are also divided. It should be noted that "1" to "5" and "R" described beside the shift grooves 81 to 83 in the drawing of FIG.

Regarding the rack and pinion mechanism 90,
The shaft 86 on the rear side of the shift drum 80 has a pinion 93.
Rack member 9 that is fixedly attached and meshes with this pinion 93
As shown in FIG. 3, 4 is arranged so as to have an angle of attack of about 30 degrees with respect to the horizontal plane and is positioned higher toward the left, and of the case member 95 of the rack unit including the rack member 94. First and second hydraulic actuators 91 and 92 each of which is composed of a hydraulic cylinder are provided at both end portions, and an output rod 91a of the first hydraulic actuator 91 is provided.
Is fixed to the left end of the rack member 94, and the output rod 92a of the second hydraulic actuator 92 is fixed to the right end of the rack member 94.

Oil chamber 91b of the first hydraulic actuator 91
When the hydraulic pressure is discharged from the oil chamber 92b of the second hydraulic actuator 92 while the hydraulic pressure is being supplied to the rack 94, the rack 94 moves to the right and the pinion 93 rotates clockwise in the rear view. On the contrary, while discharging the oil pressure in the oil chamber 91b,
When hydraulic pressure is supplied to 2b, the rack 94 moves to the left,
The pinion 93 rotates counterclockwise. Therefore, the shift drum 80 can be rotationally driven in a desired direction at a desired speed by controlling the supply, discharge, and flow rate of the hydraulic pressure to the hydraulic actuators 91 and 92.

In the figure, reference numeral 96 is a rotor member for detecting oil scattering on the shift drum 80 and rotation state of the main shaft 45, and 101 to 103 are rotor members 96 thereof.
2 is an electromagnetic pickup sensor for detecting the fin 97 of FIG. The control device (not shown) of this electronically controlled transmission TM is
Based on the command from the shift lever, the rotation speed of the counter shaft 46, the rotation speed of the main shaft 45, and the detection signal regarding the position of the rack 94, the hydraulic actuator 25, the hydraulic actuator 91 of the rack and pinion mechanism 90, 92 and the electrically controlled sub-throttle valve mechanism of the intake system of the engine are controlled, but this control system is not directly related to the present invention, and therefore its explanation is omitted.

Next, a buffer mechanism provided in a shift force transmission system for transmitting the shift force from the shift drum 80 to the synchronizing devices 67, 68, 69 via the shift rods 71-73 and the shift forks 74, 75, 76. Of the shift rods 71 to 73 due to thermal expansion or contraction of the shift rods 71 to 73, or due to the high speed rotation of the shift drum 80 at the bent portions of the shift grooves 81 to 83. A buffer mechanism (buffer means) for buffering an excessive shift force generated by the resistance of the synchronizers 67 to 69 will be described. First, as shown in FIG.
Regarding the shift grooves 81 and 83, the conventional shift groove employs a bent portion having a large degree of bending, as shown by a chain double-dashed line, but an excessive shift force is generated from the bent portion having a large degree of bending. In order to prevent this, the shape is improved to a small degree of bending as shown by the solid line. In this way, the structure in which the degree of bending is reduced also functions as a cushioning mechanism.

Compared with the conventional shift grooves, the shift grooves 81 and 83 are not only improved in shape with a small degree of bending, but also shown in FIG. 4 when shifting up from the second speed to the third speed. Before the roller 72a has completely pulled out of the second speed position P2, the roller 71a is overlapped so as to start entering the third speed position P3, and when shifting up from the fourth speed to the fifth speed, the roller 71a is moved to the fourth speed position. Before P4 is completely pulled out, the roller 73a is overlapped so as to start entering the fifth speed position P5, so that a shift change at the time of upshifting can be quickly executed.

Next, as shown in FIG. 5, the shift drum 8
0 is a gap 111 on the front end side of the shaft portion 85, a gap 112 on the rear side of the step portion of the shaft portion 86, and a gap 113 on the rear side of the pinion 93.
Is supported movably in the axial direction by about 1 to 2 mm in the axial direction. An annular needle bearing 114 and an annular rubber member 115 are interposed between the front end surface of the drum body portion 84 and the wall portion 44b of the fourth case member 44, and the rear end surface of the drum body portion 84. A ring-shaped needle bearing 116 and a ring-shaped rubber member 117 are interposed between and the wall portion 44c of the fourth case member 44. Therefore, when an excessive shift force acts on the shift rods 71 to 73 due to the rotation of the shift drum 80, the front and rear rubber members 115 and 117 buffer the excessive shift force. That is, the rubber members 115 and 117 function as a cushioning mechanism.

Next, on the shaft portion 85 of the shift drum 80,
Torsional spring 11 having a sufficiently long and relatively small spring constant
8 is externally mounted, and one end of the torsion spring 118 is attached to the wall 4
4b is fixed to the pin 119, and the torsion spring 118
The other end of the shift drum 80 is fixed to the pin 120 of the shaft portion 85, whereby the shift drum 80 is elastically biased in the direction of arrow A, which is the direction of rotation when shifting up. As a result, backlash between the pinion 93 and the rack member 94 can be eliminated, and it is possible to speed up shift-up, which requires quick shift change. However, since the torsion spring 118 is formed long enough,
The rotational drive of the shift drum 80 by the rack and pinion mechanism 90 is not restricted at all. The cushioning mechanism of this embodiment is mainly composed of a pair of rubber members 115 and 11.
7, the shift grooves 81 and 83 may be formed in the same shape as the conventional groove shape, or the torsion spring 118 may be omitted.

Among the operations of the electronically controlled transmission described above, the operations of the buffer mechanism and the torsion spring 118 will be described. As described above, when an excessive shift force is generated in the shift force transmission system due to various factors, the excessive shift force (the forward shift amount or the backward shift amount) is generated by the pair of rubber members 115. , 117, the shift drum 80 and the shift rods 71 to 7
3. Since the excessive shift force does not act on the shift forks 74 to 76, the excessive shift force does not act on the synchronizers 67 to 69, and the durability of the synchronizers 67 to 69, especially those synchronizer rings is enhanced. It is possible to reduce the shift shock at the same time. And the shift mechanism 7
0, especially shift grooves 81-83 and rollers 71a-73a
Also becomes less likely to wear and durability is improved.

Hereinafter, various modified examples or alternative embodiments of the cushioning mechanism in place of the above-mentioned cushioning mechanism will be described with reference to the drawings starting from FIG. 1] As shown in FIG. 6, as a buffer mechanism for buffering the shift force, a spring bearing ring 121 is axially immovably and rotatably attached to the longitudinal middle portion of the shaft portion 85 of the shift drum 80. On the front and rear sides of the spring receiving ring 121, the compression coil spring 1 is attached to the shaft portion 85, respectively.
22, 123 are packaged, and these compression coil springs 12
2, 123 are configured so as not to hinder the rotation of the shift drum 80. These compression coil springs 122, 123
As a result, an excessive shift force in both the front and rear directions is buffered, so that the same effect as described above can be obtained.

2] As shown in FIG. 7, the shift rod 7
At the front end portion of 2, the rubber rod 124 of a cylindrical rod shape having a short predetermined length is provided as a buffer mechanism for buffering the shift force by allowing a change in the length of the shift rod 72.
The rubber rod 124 is configured to buffer an excessive shift force acting on the shift rod 72. The rubber rod 124 does not necessarily have to be provided at the front end portion of the shift rod 72, and may be provided at an arbitrary position in the middle of the shift rod 72. A rubber rod 124 similar to the above is also provided in the middle of the other shift rods 71 and 73, but it is not shown. However, the rubber rod 124 may be interposed only in the shift rod 71, where an excessive shift force is particularly likely to act. still,
In this embodiment, the tubular members 87 to 89 are omitted and the rear end rollers 71a to 73a of the shift rods 71 to 73 are omitted.
Are directly engaged with the corresponding shift grooves 81 to 83.

3] As shown in FIG. 8, the shift rod 7
A small oil damper 125 is interposed in the middle of 2 as a buffer mechanism for buffering the shift force by allowing the change of the length of the shift rod 72, and the front rod portion 72b of the shift rod 72 is provided. Is the oil damper 12
5 is fixed to the case 126, and the shift rod 72
The rear rod portion 72c is fixed to a piston member with an orifice inside the oil damper 125. The oil damper 125 can buffer an excessive shift force acting on the shift rod 72. An oil damper 125 similar to the above is also provided in the middle of the other shift rods 71 and 73, but it is not shown. However, an oil damper may be interposed only in the shift rod 71, where an excessive shift force is particularly likely to act.
In this embodiment, the tubular members 87 to 89 are omitted, and the rollers 71a to 7 at the rear ends of the shift rods 71 to 73 are omitted.
3a is directly engaged with the corresponding shift groove 81-83.

4] As shown in FIG. 9, the shift rod 7
A load limiter 127 as a buffer mechanism for buffering the shift force is interposed in the middle of 3. The load limiter 127 includes a case 128 and the case 128.
And a holder member 129 housed in the holder member 129.
Steel ball 130 held by the spring and springs 131, 13
2, 133. The case 128 is fixed to a front rod portion 73b of the shift rod 73, and the holder member 129 is a rear rod portion 73 of the shift rod 73.
The holder member 129 is urged to the neutral position by a pair of compression springs 131 and 132 mounted on both sides of the holder member 129 in the case 128, and the steel ball 130 is moved to the outside by the compression spring 133. The case 128 is urged to form an annular or conical recess 134 on the inner surface of the case 128, with which the steel ball 130 of the holder member 129 in the neutral position is engaged.

When a load of less than a predetermined value is applied to the shift rod 73, the steel ball 130 engages with the recess 134 and the holder member 129 is held in the neutral position, but the shift rod 73 has a predetermined load. When an excessive shift force equal to or more than the value is applied, the steel ball 130 is temporarily detached from the recess 134 forward or backward, the change in the length of the shift rod 73 is allowed, and the excessive shift force is buffered. However, if the excessive shift force is eliminated thereafter, the steel ball 130 will be re-set in the recess 1
34 will be engaged. Other shift rods 7
A load limiter 12 similar to the above is also provided in the middle of 1,72.
7 is interposed, but not shown. However, the load limiter 127 may be interposed only in the shift rod 71, where an excessive shift force is particularly likely to act.

5] The shift rods 71 to 73 include:
Since a load acts on the shift forks 74 to 76, a bending moment also acts on the shift rods 71 to 73. Therefore, as a buffer mechanism that buffers the shift force through elastic deformation of the shift rods 71 to 73 in the direction orthogonal to the axis, as shown in FIG.
The cross-section secondary moment having an elliptical cross section and having the major axis of the ellipse as the neutral axis is an excessive bending moment (excessive bending moment due to an excessive shift force) acting on the shift rods 71 to 73. The value is set to a value that causes elastic deformation, and the minor axis of the ellipse is set to face the axial center of the main shaft 45.

Therefore, when an excessive shift force is about to act on the shift rods 71 to 73, the shift rods 71 to 73 are elastically deformed in the direction orthogonal to the axis to buffer the excessive shift force. The cross-sectional shape of the shift rods 71 to 73 is not limited to an ellipse, and may be formed in a rectangular shape as shown in FIG. 11, or in the middle of the shift rods 71 to 73 as shown in FIG. Notch 71 spanning a predetermined length
You may form g-73g.

6] Similar to the above 5], the shift rod 7
As a buffer mechanism for buffering the shift force through elastic deformation of 1 to 73 in the direction orthogonal to the axis, a shift rod 71 having a circular cross section is used.
~ 73 second moment of area, shift rods 71 ~ 7
The shift rod 71 for the medium speed stage is set to a value such that a slight elastic deformation is caused by an excessive bending moment (excessive bending moment due to an excessive shift force) acting on No. 3 and the shift force is maximized. Is configured to have the smallest diameter, the shift rod 72 for a low speed stage having a relatively large shift force is configured to have a slightly larger diameter than the shift rod 71, and the shift rod 73 having a small shift force is configured to be slightly smaller than the shift rod 72. Configure to a large diameter. In this way, the shift rods 71-
The diameter of 73 is made different by taking into account the shift force acting on each, and when the excessive shift force acts, the shift rods 71 to 73 are elastically deformed in the direction orthogonal to the axis to thereby prevent the excessive shift force. It can be surely buffered.

7] Next, a buffer mechanism for buffering the shift force through the elastic deformation of the shift forks 74 to 76 will be described with reference to FIGS. 13 to 16. The shift fork 74 of the three shift forks 74 to 76
For example, the shift fork 74 includes a curved plate 74a, an upper rib 74b, a lower rib 74c, a pair of upper and lower claw portions 74d and 74e, and an arm portion 74f. The pair of claw portions 74d and 74e are the synchronization device 67.
To 69 sleeves are slidably engaged respectively.

The shift fork 7 against excessive shift force
The curved plate 74a, the upper ribs 74b, and the lower ribs 74c are formed to be thinner in the direction orthogonal to the plane of the drawing in order to allow the elastic deformation of the No. 4 in the out-of-plane direction, as compared with a normal shift fork. The thickness t1 of the upper rib 74b is smaller than the thickness t2 of the lower rib 74c.
4b is formed shorter than the lower rib 74c. 14 to 16 are operation explanatory views, and when the shift force does not act, the arm portion 74f and the upper and lower ribs 74b,
The elastic deformation of 74c does not occur, and the state shown in FIG. 14 is obtained. Here, if the upper ribs 74b and the lower ribs 74c have the same bending rigidity, if a shift force acts, the arm portions 74
1 and the elastic deformation of the upper and lower ribs 74b and 74c.
The state shown in FIG.

In the shift fork 74 of this embodiment, since the rigidity of the upper rib 74b is set low, the shift fork 74 does not elastically deform to the state shown in FIG. Since the elastic device is elastically deformed, the synchronizing device 67 does not tilt with respect to the main shaft 45.
Moreover, since the curved plate 74a, the upper rib 74b, and the lower rib 74c are thinly formed in the direction orthogonal to the plane of the drawing as compared with those of a normal shift fork, when an excessive shaft force acts, Excessive shaft force is buffered through the elastic deformation of the curved plate 74a and the upper and lower ribs 74b and 74c. The shift forks 76 and 77 are also configured to allow the elastic deformation of the shift forks against an excessive shift force, similarly to the above. However,
Only the shift fork 71 in which a large shift force is likely to act may be configured to allow the elastic deformation of the shift fork against an excessive shift force as described above.

[Brief description of drawings]

FIG. 1 is a cross-sectional plan view of an electronically controlled transmission according to an embodiment.

FIG. 2 is a vertical sectional side view of the electronically controlled transmission of FIG.

FIG. 3 is a sectional view taken along line 3-3 of FIG.

FIG. 4 is a development view of an outer peripheral surface of a shift drum.

FIG. 5 is an enlarged vertical cross-sectional view of a main part of a shift drum and a buffer mechanism provided in the vicinity thereof.

FIG. 6 is an enlarged vertical cross-sectional view of a main part of a buffer mechanism according to a first alternative embodiment.

FIG. 7 is an enlarged vertical cross-sectional view of essential parts such as a shift drum and a buffer mechanism according to a second alternative embodiment.

FIG. 8 is an enlarged vertical cross-sectional view of essential parts of a shift drum, a cushioning mechanism, and the like according to a third alternative embodiment.

FIG. 9 is a sectional view of a load limiter according to a fourth alternative embodiment.

FIG. 10 is a partial perspective view of a shift rod according to a fifth alternative embodiment.

FIG. 11 is a partial perspective view of a shift rod according to a modified example of the fifth alternative embodiment.

FIG. 12 is a partial perspective view of a shift rod according to a modification of the fifth alternative embodiment.

FIG. 13 is a front view of a shift fork according to a seventh alternative embodiment.

FIG. 14 is an operation explanatory view of a shift fork according to a seventh alternative embodiment.

FIG. 15 is an operation explanatory view of the shift fork according to the seventh alternative embodiment.

FIG. 16 is an operation explanatory view of the shift fork according to the seventh alternative embodiment.

[Explanation of symbols]

 TM Electronically controlled transmission 40 Transmission gear mechanism 71, 72, 73 Shift rod 71g, 72g, 73g Notch 74, 75, 76 Shift fork 80 Shift drum 115, 116 Rubber member 122, 123 Compression coil spring 124 Rubber rod 125 Oil damper 127 Load limiter

Claims (13)

[Claims] 1. A transmission gear mechanism of a driving force transmission system of a vehicle,
An electronically controlled transmission configured to switch between a plurality of shift rods and a shift drum that axially drives the shift rods, wherein the shift drum, the shift rod, and a shift fork fixed to the shift rod are provided. At least one of the
An electronically controlled transmission, characterized in that a cushioning means for cushioning the shift force is provided. 2. The electronically controlled transmission according to claim 1, wherein the buffering means is an elastic member that elastically allows the shift drum to move in the axial direction. 3. The electronically controlled transmission according to claim 1, wherein the buffering means is configured to buffer the shift force through a change in the axial length of the shift rod. 4. The electronically controlled transmission according to claim 1, wherein the buffering means is configured to buffer the shift force through elastic deformation of the shift rod in a direction orthogonal to the axis. 5. The electronically controlled transmission according to claim 1, wherein the buffering means is configured to buffer the shift force through elastic deformation of the shift fork. 6. The electronically controlled transmission according to claim 3, wherein the buffering means is an elastic member incorporated in a shift rod. 7. The shock absorbing means comprises an oil damper incorporated in a shift rod.
The electronically controlled transmission according to. 8. The electronically controlled transmission according to claim 3, wherein the buffering means is a load limiter incorporated in the shift rod to block transmission of a shift force of a predetermined value or more. 9. The electronically controlled transmission according to claim 4, wherein the buffering means has a configuration in which the cross-sectional shape of the shift rod is elliptical. 10. The electronically controlled transmission according to claim 4, wherein the buffering means has a configuration in which a cross-sectional shape of the shift rod is rectangular. 11. The electronically controlled transmission according to claim 4, wherein the buffering means has a structure in which a middle portion of the shift rod is partially cut away. 12. An electronically controlled transmission, wherein a transmission gear mechanism of a driving force transmission system of a vehicle is configured to be switched via a plurality of shift rods and a shift drum that axially drives these shift rods. An electronically controlled transmission, characterized in that the plurality of shift rods have different diameters for each gear. 13. The electronically controlled transmission according to claim 13, wherein the shift rod for the medium speed stage has a smaller diameter than the shift rods for the other shift stages.