JPH063260B2 - Gear change operation device of tractor - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a speed change operation device for a tractor.

(Prior Art) There is a technique disclosed in Japanese Utility Model Publication No. 53-299295 as a technique for narrowing the width of a transmission case as a gear shift operating device of a tractor.

That is, as shown in FIG. 10, a hole 3 is formed in the side wall 2 of the mission case 1, and the fork shafts 4, 5, 6 are arranged side by side in a vertical plane in a plurality of upper and lower stages, and the shafts 4, 5, 6 , Forks 7, 8 having engaging portions 7A, 8A, 9A protruding outward from the hole 3,
A shift lever 10 having a shift rod 10A that supports 9 and engages with the engaging portions 7A, 8A, 9A is operated around a fulcrum 11 located above the engaging portion.

(Problems to be Solved by the Invention) In the prior art, since the fork shafts 4, 5, 6 are arranged in parallel on the vertical plane, the width of the mission case 1 can be narrowed to some extent. , Engagement part 7
Shift rod 10A of shift lever 10 that can be engaged and disengaged with A, 8A, and 9A
Was required to return to the neutral position.

Therefore, if each of the engaging portions 7A and 9A is provided with a neutral piece for neutral return, the structure is complicated and the assembly is troublesome.

It is an object of the present invention to further exert the advantages of the conventional technique and solve this problem.

(Means for Solving Problems) The present invention is provided with transmission shafts 23, 33 arranged in parallel in a plurality of upper and lower stages in a transmission case 63, and transmission gear groups 27, 28, 28 on the transmission shafts 23, 33 are provided. Fork shafts 44, 45, 46 in which forks 50, 51, 52 for shifting 36, 37, 30, 31, 32, 38, 39, 40 are arranged side by side in upper and lower stages outside the speed change shafts 23, 33. Is slidably supported through the engaging portions 53, 54, 55 on the fork shafts 44, 45, 46 side.
Is provided corresponding to the hole 65 formed in the side wall 64 of the mission case 63, and the engagement member 53,
An operation fulcrum 69 of the shift lever 61 that can be freely engaged and disengaged is provided at 54 and 55, and the operation fulcrum 69 is arranged outside the side wall 64 of the mission case 63 above the engaging portions 53, 54 and 55. The above-mentioned object was achieved by taking the following technical measures.

That is, according to the present invention, the speed change lever 61 on the side projecting outward from the operation fulcrum 69 is formed heavier than the speed change rod 62 extending inward from the operation fulcrum 69, and the speed change rod 62 is engaged with the lower engagement step. Department
It is separated from 53 to neutrally return to the adjacent middle-stage engaging portion 55, and the receiver 66A of the coil spring 74 provided around the speed-changing rod 62 is set on the transmission table 66, and the shift rod 62 is held by the coil spring 74. A mechanism 56 that is formed in 55 for neutral return, and further that the shift rod 62 is neutrally returned to the middle engagement portion 55 in the upper engagement portion 54.
Is provided.

(Operation) The shift lever 62 of the shift lever 61 is connected to the middle engagement portion of the fork shaft 46.
When it is engaged with 55 and operated in the front-back direction around the operation fulcrum 69, the fork shaft 46 slides in the axial direction, the shifter 29 slides by the fork 52, and the gear groups 27, 36, 37, 28 move. The speed is changed to high speed H and low speed L, respectively.

In the state where the gear group 27, 36, 37, 28 shifts to either the high speed H or the low speed L, the shift lever 61 is moved to the upper and lower engaging portions.
When either one of 53, 54 is engaged and one of the fork shafts 44, 45 is slid, at low speed L, the 3rd speed shift 1F, 2F,
3F is shifted to 4F, 5F and 6F at high speed H by gear groups 30, 31, 32, 38, 39 and 40, respectively.

In this case, when the gear shift lever 61 is operated in the arrow C direction in FIG. 4 and the hand is released, the lever 61 returns in the arrow B direction by its own weight, and the urging force of the coil spring 74 moves the gear shift rod 62 to the neutral position. Then, the neutral return mechanism 56 returns from the upper side.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

In FIG. 2, reference numeral 20 is an input shaft, and a wall is provided through a bearing 21.
It is supported by 22 and is linked to the engine via a clutch (not shown).

Reference numeral 23 denotes a speed change shaft, which is installed as a common shaft center with the input shaft 20, and one end thereof is supported by the input shaft 20 via a needle bearing 24,
The other end is supported on the wall 25 by a bearing 26.

Reference numeral 27 denotes an input gear, which is attached to the rear end of the input shaft 20 by a spline or the like, and the gear 27 has an engaging portion 27A.

Reference numeral 28 denotes a low speed transmission gear, which is rotatably fitted and supported on the speed change shaft 23, and the gear 28 has an engaging portion 28A.

Reference numeral 29 is a shifter for switching between high and low, which is provided on a coupling ring that is fitted and fixed on the speed-change shaft 23 so as to be slidable in the axial direction. It is said that it can be engaged and disengaged.

30 is a first speed transmission gear, 31 is a second speed transmission gear, 32
Is a transmission gear for the third speed, and these gears 30 to 32 are fitted onto the transmission shaft 23 by a spline or the like.

Reference numeral 33 denotes an output-side speed change shaft, which is installed below the input-side speed change shaft 23 in parallel with the walls 22 and 25 via bearings 34 and 35.

The speed change shaft 33 is interlockingly connected to the drive wheels of the tractor via a differential device (not shown).

36 is a low speed system first interlocking gear, which is in mesh with the input gear 27, and 37 is a low speed system second interlocking gear, which is in mesh with the transmission gear 28, and is the first and second interlocking gears. 36 and 37 have an integral gear structure and are rotatably fitted onto the transmission shaft 33.

38, 39, 40 are first to third speed transmission gears,
The transmission gears 30, 31, 32 are engaged with the transmission gears 30, 31 and 32, and are fitted and supported on the transmission shaft 33 so as to be rotatable relative to each other.
8, 39, 40 have occlusal parts 38A, 39A, 40A.

41 is the first speed and the second speed (also used for the fourth speed and the fifth speed)
A shifter for switching, which is slidably mounted on the coupling ring fixedly fitted on the speed change shaft 33 in the axial direction. In this example, it is selectively engageable with and disengageable from the occlusal portions 38A, 39A via the synchronizing means. It is said that.

42 is a shifter for switching the third speed (also for the sixth speed),
A coupling ring, which is fitted over and fixed to the speed-change shaft 33, is provided so as to be slidable in the axial direction.
It is said to be able to engage and disengage at 40A.

Reference numeral 43 is a shift fork shaft device, and as shown in FIGS. 1 and 3, a first fork shaft 44 for the first speed and the second speed, a second fork shaft 45 for the third speed, and a high / low switching. And a third fork shaft 46 for use in the upper and lower stages on the outer side of the speed change shafts 23 and 33, that is, the first fork shaft 44 is on the outer side of the lower stage, and the third fork shaft 46 is on the middle stage. The two fork shafts 45 are slidably supported by the front and rear walls 22 and 25 on the inclined plane AA so as to be located inward of the upper stage and parallel to each other in the axial direction.

It should be noted that interlocking circumferential grooves 44A, 45A, 46A and positioning circumferential grooves 44B, are formed at both axial ends of each fork shaft 44, 45, 46.
45B and 46B are formed, a ball 47 is provided in the interlocking circumferential groove, and a spring 48 is provided in the positioning circumferential groove as shown in FIG.
The ball 49 urged by is engaged, and in this case, the positioning circumferential groove 46B for height is shallower than the groove depth of the other circumferential grooves 44B, 45B, and the depth of the spring accommodating hole is deep. The operation load (resistance) is reduced here compared to other fork shafts so that the shift position can be easily confirmed.

50, 51, 52 are forks, and each fork shaft 44, 45, 46
The boss portions 50A, 51A, 52A of the base thereof are fitted and fixed onto the upper portion, and the fork 50 is engaged with the shifter 41,
51 is engaged with the shifter 42, and the forks 51 are engaged with the shifter 29 from the outside.

Here, the third fork shaft 46 is in the middle stage, and the first fork shaft 44 and the second fork shaft 45 are positioned inside and below the upper and lower sides,
The forks 50 and 51 on the first and second fork shafts 44 and 45 are arranged downward as shown in FIGS. 1 and 5, and the fork 52 on the third fork shaft 46 is arranged upwards. A through hole 52B is formed on the base side of the fork 52, and the through hole 5B is formed.
The second fork shaft 45 is inserted into 2B, and the fork 52 is inserted there.
It is possible to arrange without circumventing the outside.

The through hole 52B and the fork shaft 45 may be slidably in contact with each other so as to have a guide function, but the through hole 52B may be a so-called stupid hole to prevent contact with the fork shaft 45 to reduce resistance. Good.

The fork shafts 44, 45, 46 are provided with upper, middle, and lower engaging portions 53, 54, 55, respectively.
First and second axially opposite sides of the middle engaging portion 55 of
The lower speed engaging portion 53 for the speed and the upper engaging portion 54 for the third speed are respectively recessed, and the engaging portion 54 for the third speed is provided with a neutral return mechanism 56 with a space in the axial direction. Has been.

That is, as shown in FIGS. 3 and 6, the neutral return mechanism 56 has a holder 57 fixedly mounted on the fork shaft 45 and a pair of sliding holes 58 formed in a direction orthogonal to the fork shaft 45. A neutral piece 59, which is biased by a spring, is slidably inserted into the moving hole 58, and the neutral piece 60 is biased to bias the shift rod 62 of the shift lever 61 to the neutral position.

Holes (windows) 65 are formed in the side wall 64 of the mission case 63 as shown in FIGS. 1 and 2, and the engaging portions 53, 54, 55 corresponding to the holes 65 are formed from the holes 65. The hole 65 is arranged on the inner side, and the hole 65 is closed by a transmission 66.

The transmission 66 is attached to the side wall 64 with bolts 67, and a spherical seat 68 is formed above the engaging portions 53, 54, 55.

A spherical body 69 is fitted onto the speed change lever 61 and is fixed thereto by welding or the like. The spherical body 69 is fitted to the receiving seat 68, which constitutes an operation fulcrum 69 of the speed change lever 61. Operation fulcrum 69
The speed change rod 62 extending through the twisted hole 65 is made substantially orthogonal to the inclined plane A-A so that the end of the speed change rod 62 (spherical shape, that is, curved as shown in FIG. 7). The surface 62A may be provided in each engaging portion 53, 54, 55.
It can be engaged and disengaged on the inner side than 5.

The spherical body 69 is provided with two slits 70 penetrating in the axial direction on one side, and a slit 71 on the other side on the other side. The set pin 72 and the guide pin 73 are attached to the respective slits 70, 71 from the outside. The set pin 72 to the spherical body 69.
Of the spherical body 69, that is, the shift lever 61 is prevented from coming off.

A conical (coil-shaped) spring 74 having a large-diameter end 74A and a small-diameter end 74B is provided around the speed change rod 62. The large-diameter end 74A is attached to a receiver 66A formed in the transmission 66, and the small-diameter end 74B is It engages with a spring receiver 74C attached to the speed change rod 62 and urges it in a direction to prevent the speed change rod 62 from coming off. Then, as shown in FIG. 1, the receiver 66A is tilted in an oblique direction with respect to the axis of the speed change rod 62, whereby the speed change rod 62 is returned to the middle engagement portion 55 by the urging force of the spring 74.

The speed change lever 61 extends upward and outward from the operation fulcrum 69 and penetrates the floor sheet of the tractor or the cabin floor 75 as shown in FIG. 4, where the speed change lever 61 is located outside the operation fulcrum 69. The own weight is large, and a tilting force is applied to the middle gear as shown by the arrow B in FIG. 4 by its own weight. As a result, the gear shifting rod 62 having the curved surface 62A is adjacent to the engaging portion 53 in the middle engaging portion. It is designed to return to neutral by its own weight and the coil spring 74 with respect to 55, and from the upper engagement portion 54 to the middle engagement portion.
The neutral return mechanism 56 for 55 is returned to the neutral position.

As shown in FIG. 7 (a), the axial lengths of the upper and lower engaging portions 53, 54 are made shorter than the axial length of the middle engaging portion 55, and a step D is formed there. Further, as shown in FIG. 7 (b), the step D is formed by making the axial lengths of the upper and lower engaging portions 53, 54 longer than the axial length of the middle engaging portion 55.

Next, the operation operation of the embodiment of the present invention will be described.

The gear shift lever 61 is heavier on the outer side than the operation fulcrum 69 as shown by the arrow B, and is biased by the coil spring 74.
The gear rod 62 is brought into contact with the gear 60, and even if the gear shift lever 61 moves due to vibrations or the like, the gear shift rod 62 is securely held by the engaging portion 55 of the fork shaft 46 for height adjustment, and is thereby in the neutral state.

Therefore, when the speed change lever 61 is rotated in the front-rear direction about the operation fulcrum 69, the fork shaft 46 is slid in the axial direction,
As a result, the shifter 29 is slid to either H or L in FIG. 3 by the fork 52.

When the shifter 29 is engaged with the occlusal portion 28A of the gear 28, the transmission shaft 23 is transmitted at a low speed from the input shaft 20 through the gear 27, the gear 36, the gear 37, and the gear 28. 61 in the direction of arrow C in FIG.
When the lever is operated against the urging force of the coil spring 74 with the fulcrum as a fulcrum, the shift rod 62 is engaged with the engaging portion 53 of the fork shaft 44, and when the shift lever 61 is slid in the front-rear direction in this engaged state, The shaft 44 slides in the axial direction and the fork 50 shifts the shaft.
41 is engaged with either the occlusal portion 38A of the gear 38 or the occlusal portion 39A of the gear 39, where the first speed or the second speed is changed and output from the speed change shaft 33.

When the gear lever 61 is released in the state of the first speed or the second speed, the gear lever 61 is returned by its own weight in the direction of the arrow B, and the gear rod 62 is moved to the neutral position by the urging force of the coil spring 74. It automatically returns and, in combination with the neutral return mechanism 56, prevents unexpected shift to the shift position even if vibration or the like is received.

Next, in the low speed transmission L, when the speed change lever 61 is operated in the direction of arrow D in FIG. 4, the speed change rod 62 moves to the neutral piece.
Push the 60 against the spring 59 to engage the engaging portion 54 of the fork shaft 45.
When the gear shift lever 61 is rotated in this state, the fork shaft 45 is slid, and the fork 51 slides the shifter 42 in the 3F (L) direction of FIG.
By engaging 40A, the third speed is obtained here.

When the shifter 29 is engaged with the occlusal portion 27A of the gear 27, the input shaft 20 and the speed change shaft 23 are directly connected to each other and become high H. In this high speed transmission, the shifters 41 and 42 are moved to the 4F of FIG. 5F, 6F, here, high speed 3 steps,
That is, 4F, 5F, and 6F are obtained.

Further, in the operation of the speed change rod 62, in FIG.
Before and after the operation from 3 or 54 to the middle engagement portion 55, the neutral position is sensuously grasped by the resistance due to the step D.
In the case of (b), the step D
It is intuitively understood that the resistance of will soon enter the neutral position.

(Effects of the Invention) According to the present invention, the gearshift lever projecting outward from the operation fulcrum is formed to be heavier than the gearshift rod extending inward from the operation fulcrum, and the gearshift rod is provided from the engaging portion. Since it is disengaged and neutrally returned to the adjacent engaging portion, the neutral return is made by the biasing force of the coil spring provided around the speed change rod.
The gear shift lever automatically returns to the neutral position, no manual operation is required here, and the neutral engaging mechanism does not need to be built in the lower engaging portion, so that the assembling can be simplified.

In addition, a neutral return mechanism is provided in the upper engagement part, and the lower side is designed to return to neutral by the biasing force of the coil spring for fixing the gearshift rod and the weight of the gearshift lever. It's safe,
Since the lower side neutral return is also used as the coil spring for fixing the speed change rod, the number of parts can be reduced. Further, since the self-weight is applied, a normal coil spring can be used.

[Brief description of drawings]

The drawings show an embodiment of the present invention and a conventional example, FIG. 1 is an elevation sectional view of an embodiment of the present invention, FIG. 2 is a side view of the same mission, and FIG. 3 is a developed plan view showing a fork shaft arrangement, Fig. 4 is an overall rear view, Fig. 5 is a rear view showing the fork arrangement, Fig. 6 is a detailed sectional view of the engaging portion, and Figs. 7 (a) and (b) are two examples of the engaging portion. FIG. 8 is a sectional view of the positioning mechanism, FIG. 9 is an explanatory view showing a shift pattern, and FIG. 10 is an elevation sectional view of a conventional example. 20 ... Input shaft, 23, 33 ... Shift shaft, 27, 28, 36, 37, 30, 3
1, 32, 38, 39.40 ... Speed change gear group, 29, 41, 42 ... Shifter, 44, 45, 46 ... Fork shaft, 53, 54, 55 ... Engaging portion,
61 ... gearshift lever, 62 ... gearshift rod, 63 ... mission case,
64 ... Wall, 65 ... Pieces, 66 ... Gearbox, 66A ... Spring receiver, 69 ... Operation fulcrum, 74 ... Coil spring.

Claims (1)

[Claims] 1. Transmission shafts 23, 33 in a mission case 63.
Are arranged side by side in a plurality of upper and lower stages, and forks 50, 51, 52 for shifting the speed change gear groups 27, 28, 36, 37, 30, 31, 32, 38, 39, 40 on the speed change shafts 23, 33 are provided. , The fork shafts 44, 45, 46 slidably supported on the outer sides of the speed change shafts 23, 33 through the fork shafts 44, 45, 46 arranged in parallel in the vertical direction, and the engaging portions 53, 5 on the fork shafts 44, 45, 46 side.
Holes 65 formed in side wall 64 of mission case 63
The fulcrum of the shift lever 61, which is provided corresponding to the above, and which is engageable with and disengageable from the engaging portions 53, 54, 55, on the shift stand 66 that closes the hole 65.
69 is provided and the operation fulcrum 69 is arranged outside the side wall 64 of the mission case 63 above the engaging portions 53, 54, 55, and the gear shift lever 61 on the side projecting outward from the operation fulcrum 69 is provided. ,
It is formed to be heavier than the speed change rod 62 extending inward from the operation fulcrum 69, and the speed change rod 62 is disengaged from the lower engagement portion 53 and neutrally returned to the adjacent middle engagement portion 55. The support 66A of the coil spring 74 provided around the speed change rod 62 is attached to the speed change stand 66.
Further, the coil spring 74 is formed to neutrally return the speed change rod 62 to the middle engagement portion 55, and the upper engagement portion 54 is provided with a mechanism 56 for neutrally returning the speed change rod 62 to the middle engagement portion 55. A gear shifting operation device for a tractor.