JP4382954B2 - Four-wheel drive work vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is provided with a front wheel transmission that presents a standard state in which the rotational speeds of the front and rear wheels are set to the same speed and an accelerated state in which the front wheels are rotated at a higher speed than the rear wheels, and an operation for switching the traveling direction of the vehicle body. A linkage rod that operates in conjunction with the steering operation of the steering device in the left-right direction is brought into contact with a transmission switching lever that switches the front wheel transmission device between the standard state and the acceleration state, and the transmission switching lever is standardized. Maintaining the operating position and operating in conjunction with the steering operation of the steering device, allowing the shift switching lever to move to the speed increasing operation position, and directing the speed changing lever toward the speed increasing operation position. The present invention relates to a four-wheel drive work vehicle in which an urging spring that urges is provided and the urging spring is externally fitted to the linkage rod.
[0002]
[Prior art]
In order to provide an urging spring for urging the speed change lever toward the speed increasing operation position, the connecting rod linked to the steering device is inserted through a hole provided at the lower end of the speed change lever. The compression coil spring is externally fitted to the extending portion of the linkage rod that penetrates the lower end of the speed change lever. Then, when the steering device steers left and right, the linkage rod is pulled to compress the compression coil spring, and at the same time, the shift switch lever is switched to the acceleration operation position, and after the shift switch lever is switched to the acceleration position, There is no change in the position of the speed change lever until the steering device reaches the maximum turning angle, but the compression coil spring is gradually compressed to the shortest length (for example, Japanese Patent Laid-Open No. Hei 8- No. 300962).
[0003]
[Problems to be solved by the invention]
In the above conventional configuration, since the compression coil spring is mounted on the portion of the linkage rod that protrudes from the gear change lever, the mounting portion protrudes greatly, and it is necessary to reconstruct the arrangement in order to occupy a large space. was there. In addition, a friction multi-plate clutch mechanism is provided in order to reveal the speed-up state as the structure of the front wheel transmission, and the compression force of the friction multi-plate increases as the urging force of the compression coil spring increases. Since the multi-plate compression force becomes the travel drive force, immediately after switching to the speed increasing state, the travel drive force is small and the travel drive force increases as the compression force increases.
Therefore, immediately after switching to the acceleration state, the driving force may be insufficient during the wet paddy field work.
[0004]
An object of the present invention is to provide a space-efficient installation of the urging means and a device capable of ensuring a traveling driving force in an accelerated state.
[0005]
[Means for Solving the Problems]
(Constitution)
The invention according to claim 1, provided with a standard state of setting the rotational speed of the front and rear wheels in the same speed, a front wheel speed change device for revealing the accelerating state of rotating the front wheel faster than the rear wheel, a clutch for revealing the accelerating state of the front wheel transmission, and a shift switching lever for switching and operating the front wheel transmission to said acceleration state and said standard state by operating the clutch is provided,
A linkage rod that operates in conjunction with a steering operation in the left-right direction of the steering device that switches the advancing direction of the machine body is provided, and a through hole is formed in a connecting shaft provided in the shift switching lever, and the linkage rod is formed in the through hole. The one end portion of the shift switching lever side is penetrated, and the linkage rod is supported on the coupling shaft so as to be relatively movable, and is configured to be able to contact the coupling shaft in the penetration state.
Wherein the contact between the connecting shaft of the link rod while maintaining the gear shifting lever to the standard operating position, the connecting shaft interlock the previous SL shift to the steering operation of the steering device by relative movement of the linkage rod Allow the switch lever to move to the speed increasing position,
Outside portion located between the shift switching lever is provided an urging spring for urging said acceleration operating position direction, the biasing spring and the steering device in the linkage rod the gear shifting lever was fitted to, hermetically engaging hooking one end of the gear shifting lever side of the biasing spring to the outer periphery of the connecting shaft, the other end of the biasing spring and the steering device in the linkage rod and the gear shifting lever It is in the point attached to the part located between, The effect is as follows.
[0006]
(Effect) In other words, as a method of providing the urging spring, conventionally, the transmission switching lever is purposely penetrated and the coil spring is externally fitted to the extended portion of the linkage rod that has been seen through. Since the part has been improved, it is provided by being fitted on the part spanned between the steering device of the linkage rod and the gear change lever, so to speak, as a part that links the steering device and the gear change lever. It was provided in a necessary part and a part that can be considered as an empty space, and a space-efficient arrangement configuration could be adopted.
[0007]
[0008]
[0009]
[0010]
Furthermore, according to the structure of Claim 1, there exist the following effects.
In other words, an urging spring provided by being externally fitted to the linkage rod is stretched between the gear change lever and the link rod, so that the desired clutch is required when the gear change lever is in the standard operating position. It is possible to configure the system so that the pressure can be generated, and setting the pressure does not cause the driving force to be insufficient even if the speed is switched to the speed increasing state.
Specifically, even if the biasing spring is provided with an initial tension sufficient to reveal the speed increasing state and is provided between the speed change lever and the linkage rod, the speed change lever is not in contact with the speed rod. Keep the standard state without moving. When the steering device is activated and the linkage rod moves to a state that allows the shift change lever to move to the acceleration operation position, the shift change lever is driven together with the linkage rod by the spring force of the urging spring to increase the acceleration operation position. Switch to. In this case, since the tensioning length of the biasing spring does not change during the movement stroke from the standard operation position of the speed change lever to the speed increasing position, the initial biasing force acts on the speed change lever as it is. Presents the compression force required for the condition. After the gear change lever is switched to the speed increasing position, until the steering device reaches the steering limit, the speed change lever is maintained at the speed increasing position, and only the linkage rod becomes the speed change lever. Move relative to it. Therefore, during this time, the shift switching lever and the linkage rod move relative to each other and the urging force slightly increases. However, since the relative moving distance is short, the change in the urging force can be reduced as compared with the conventional case.
[0011]
(Structure) The invention according to claim 2 adjusts the extension length of the biasing spring across the other end of the biasing spring on the side opposite to the speed change lever side and the linkage rod. The operation and effect are as follows.
[0012]
(Function and effect) In other words, since a mechanism for adjusting the tensioning length of the biasing spring is provided, the position where both ends of the biasing spring are stopped is set to a rough position and adjusted with the biasing spring attached. This is effective when assembling the equipment.
[0013]
(Structure) The invention according to claim 3 is that the urging spring is constituted by a tension coil spring, and the operation and effect thereof are as follows.
[0014]
(Effect) That is, since only the coil portion of the tension coil spring is externally fitted to the linkage rod, no other mechanism is required for externally fitting the biasing spring to the linkage rod, and the tension coil spring is used. Therefore, it is only necessary to provide a stop mechanism for locking both ends, and the stop structure is simple.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
An agricultural tractor as a four-wheel drive work vehicle will be described. As shown in FIGS. 1 and 3, a steering unit 3 is provided at the center of the airframe supported by a front wheel 1 and a rear wheel 2 that can be steered. 6, the first transmission gear 7, the second transmission gear 8, and the first transmission shaft 9 are used to transmit power to the transmission case 10 at the rear of the machine body, and the front wheels are disposed below the main clutch 5 on the rear side of the front wheels 1. A transmission 11 is arranged to transmit power from the transmission case 10 to the front wheel transmission 11 via the second transmission shaft 12 and to transmit the power from the front wheel transmission 11 to the front axle via the front wheel output shaft 13. It is transmitted from the case 14 to the front wheel 1.
[0016]
The front wheel transmission 11 will be described.
As shown in FIG. 3, the input shaft 15 and the output shaft 16 are arranged vertically on the lower side of the main clutch 5, and the second transmission shaft 12 from the transmission case 10 is connected to the input shaft 15. A standard input gear 17 and a speed increasing input gear 18 are formed on the input shaft 15, and the standard input gear 17 is engaged with a standard output gear 19 that is externally fitted to the output shaft 16 so as to be relatively rotatable. The speed increasing input gear 18 is engaged with the gear 20a of the multi-plate friction clutch 20. A shift member 21 is fitted on the output shaft 16 by a spline, and the shift member 21 is urged toward the standard output gear 19 by a spring 22.
[0017]
As shown in FIG. 3, in this state, the shift member 21 is engaged with the standard input gear 19 by the biasing force of the spring 22 in a normal state, and the power transmitted to the input shaft 15 is transmitted to the standard input gear 19 and the output. The transmission is transmitted to the front wheel output shaft 13 through the shaft 16 and the output gear 23 in a standard state in which the front wheels 1 and the rear wheels 2 are driven at substantially the same speed. When the shift member 21 is slid in the right direction in FIG. 3 and the friction clutch 20 is pushed in, the power transmitted to the input shaft 15 is transmitted to the front wheels via the friction clutch 20, the output shaft 16 and the output gear 23. This is transmitted to the front wheel output shaft 13 in an accelerated state driven at a higher speed than the first and rear wheels 2.
[0018]
The sliding operation structure of the shift member 21 of the front wheel transmission 11 will be described. As shown in FIGS. 3 and 4, the first operation shaft 24 and the second operation shaft 25 are rotatably supported on the lower portion of the case 27 covering the front wheel transmission 11, and the shift is fixed to the second operation shaft 25. The fork 25 b is engaged with the shift member 21 of the front wheel transmission 11. As shown in FIG. 6, a boss member 26 is externally fitted to the first operation shaft 24 so as to be integrally rotatable and slidable, and an operation arm 26 a fixed to the boss member 26 is fixed to the second operation shaft 25. The arm 25a is in contact with the arm 25a from above. The first operating shaft 24 is protruded laterally outward from the case 27, and a shift switching lever 28 is fixed to the protruding end as shown in FIG.
[0019]
As shown in FIGS. 1 and 2, a balance arm 29 that swings along the longitudinal axis P <b> 1 of the airframe is supported around the longitudinal axis P <b> 1 of the rear portion of the front axle case 14, and the front wheel 1 is attached to the front axle case 14. A front wheel support member 30 that is swingably supported with respect to the front wheel support member 30, and a knuckle arm 30A that swings integrally with the front wheel 1 provided on the front wheel support member 30 and a balance arm 29 are connected to each other. Yes. A steering gear box 46 and a pitman arm 47 are arranged in the front part of the front axle case 14, and the pitman arm 47 and the left and right knuckle arms 30A are connected via tie rods 48. The steering part 3 shown in FIG. A steering device A is configured by connecting the steering handle 45 and the steering gear box 46 by a steering shaft 49.
As shown in FIGS. 1, 2, and 4, the linkage rod 32 is disposed on the front wheel 1 side, and a coil-like tension spring 33 is externally fitted to the linkage rod 32, and the linkage rod 32 and the spring 33 form the linkage mechanism 34. It is composed. The end of the linkage rod 32 is connected to the end of the balance arm 29, and the end of the spring 33 is connected to the speed change switching lever 28. As shown in FIGS. 4, 6, and 7, the connecting shaft 35 provided with the through hole 35 a is rotatably supported by a bracket portion 28 </ b> A formed at the lower end of the speed change lever 28, and at one of the inlet portions of the through hole 35 a. A receiving plate 36 is provided, and the receiving plate 36 is attached to the connecting rod 32 in a state where a hole formed in the receiving plate 36 is communicated with the through hole 35a. The distal end small diameter portion 32a of the linkage rod 32 is passed through the hole of the receiving plate 36 and the through hole 35a of the connecting shaft 35, and the distal end small diameter portion 32a of the linkage rod 32 and the intermediate large size following the distal end narrow diameter portion 32a are connected. The step part 32c formed between the diameter parts 32b is configured to contact the receiving plate 36.
[0020]
As shown in FIG. 9, a part of the linkage rod 32 is formed on the screw shaft, and a locking ring body 44 that locks one end of the urging spring 33 on the screw shaft is externally fitted. One end of the urging spring 33 is locked to the locking pin 44A. A nut 45 is screwed onto the shift switching lever 28 side of the locking ring body 44 so that the locking position of the locking ring body 44 can be adjusted. Here, the nut 45 and the locking ring body 44 constitute a mechanism B that adjusts the extension length of the urging spring 33 .
[0021]
The state shown in FIG. 2 is a state in which the front wheel 1 is operated to the rectilinear position by the steering handle 45, and the shift member 21 of the front wheel transmission 11 is moved by the urging force of the spring 22 as shown in FIG. 19 is in a standard state where the front wheel 1 and the rear wheel 2 are driven at substantially the same speed.
When the front wheel 1 is steered to the right or left by the steering handle 45 from this straight traveling position, the knuckle arm 30A is swung to the right or left in FIG. 2, and the linkage rod 31 is moved to the front wheel support member. Pull to 30 side. As a result, the balance arm 29 is swung counterclockwise in FIG. 2 to pull the linkage rod 32 toward the front wheel 1, and the linkage rod 32 is pulled to control the movement by the linkage rod 32. The gear change lever 28 is deregulated, and the gear change lever 28 is swung in the clockwise direction in FIG. 4 by the urging force of the spring 33, and is operated by the operation arm 26 a of the boss member 26 of the first operation shaft 24. Then, the operating arm 25a of the second operating shaft 25 is pushed downward in the drawing of FIG. 4, the second operating shaft 25 is rotated in the clockwise direction of FIG. 3, and the shift fork 25b is used to shift the shift member of the front wheel transmission device 11. At 21, the sliding operation is performed to the friction clutch 20 side (acceleration state side).
[0022]
Then, when the front wheel 1 is steered to the right or left set angle, the gear change lever 28 is swung to the position shown in FIG. 4, and the shift member 21 of the front wheel transmission 11 presses the friction clutch 20. When operated, the shift member 21 is no longer slid, and the front wheel 1 is driven at a higher speed than the rear wheel 2.
When the front wheel 1 is further steered to the right or left set angle from this state and the linkage rod 32 is pulled toward the front wheel 1 side, the shift member 21 and the shift switching lever 28 of the front wheel transmission 11 are moved. The linkage rod 32 is slid to the front wheel 1 side with respect to the connecting shaft 35 of the speed change lever 28 while the friction clutch 20 is left at the position where the friction clutch 20 is pressed and operated. However you stretched initialization length so as to ensure a minimum biasing force only presses the friction clutch 20 in this state.
[0023]
In this agricultural tractor, when the front wheel 1 is steered to the right or left by the steering handle 45, a state in which the front wheel transmission 11 is switched from the standard state to the acceleration state and a state in which the switching operation is not performed are set. This structure will now be described.
As shown in FIGS. 4, 7, and 8, the vertical operation shaft 40 is rotatably supported by the case 27 of the front wheel transmission 11, and the operation arm 40 a of the operation shaft 40 is supported by the boss member 26 of the first operation shaft 24. Is engaged. As shown in FIGS. 4 and 7, a bell crank-shaped operation member 41 is swingably supported around the lateral axis P <b> 2 outside the case 27, and the operation arm 40 b of the operation shaft 40 and the operation member 41 are One end is connected by a linkage rod 42. A linking rod 44 is connected across a switching lever (not shown) provided at the top of the control unit 3 and the operation member 41, and a speed change lever (not shown) provided on the side of the control unit 3; The connecting rod 43 is connected to the operation member 41.
[0024]
The state shown in FIGS. 6 and 7 is a state in which the switching lever is operated to the ON position and the speed change lever is operated to the low speed side. In this state, the boss member 26 of the first operating shaft 24 is slid upward in FIG. 7 , and the positions of the operating arm 26a of the boss member 26 and the operating arm 25a of the second operating shaft 25 are as shown in FIG. As shown in FIG.
In this state, when the front wheel 1 is steered right or left by the steering handle 45 as described above, and the first operation shaft 24 and the boss member 26 are rotated clockwise in FIG. 4, the boss member The operation arm 26a of 26 comes into contact with and pushes the operation arm 25a of the second operation shaft 25, thereby switching the front wheel transmission 11 from the standard state to the acceleration state.
[0025]
Conversely, when the switch lever is operated to the OFF position, the linkage rod 42 is operated to be pulled upward in FIG. 7, and when the speed change lever is operated to the low speed side, the linkage rod 43 is pulled to the right in FIG. 41 is swung counterclockwise in FIG. As a result, the boss member 26 of the first operating shaft 24 is slid downward in the drawing of FIG. 7, and the operating arm 26a of the boss member 26 deviates from the position of the operating arm 25a of the second operating shaft 25 downward in the drawing of FIG. .
Therefore, even if the front wheel 1 is steered to the right or left by the steering handle 45 in the above state, even if the first operation shaft 24 and the boss member 26 are rotated clockwise in FIG. The operating arm 26a does not come into contact with the operating arm 25a of the second operating shaft 25, and the front wheel transmission 11 is not switched to the accelerated state and remains in the standard state.
[0026]
The matters described below do not require rights.
With the structure indicated by the paragraph number [0019], the linkage rod 32 is slidably supported with respect to the connection shaft 35 in the left-right direction in FIG. 4 and fixed to the speed change lever 28 as shown in FIGS. A configuration is adopted in which a desired urging force necessary for switching the shift switching lever 28 to the speed increasing position is applied by a spring 33 spanned between the frame 37 and the frame 37. Therefore, the spring 33 applies a biasing force to move the shift switching lever 28 in the left direction in FIG. 4 and the stepped portion 32c of the linkage rod 32 that is fixed when the handle operation is not performed is the receiving plate 36. Swaying of the linkage rod 32 and the shift switching lever 28 is restricted. In this state, the spring 33 is stretched to the length of a state that exerts an urging force sufficient to reveal the accelerated state.
As shown in FIGS. 4 and 5, a locking member 38 for locking one end of the spring 33 is provided between the fixing member 37 and one end of the tension spring 33 connected to the fixing member 37. Is attached to the fixing member 37 by a nut 39. By adjusting the rotation of the nut 39, the amount of the engagement of the locking metal 38 in the tensioning direction of the spring 33 is adjusted to adjust the tensioning force of the tension spring 33.
[Brief description of the drawings]
FIG. 1 is an overall side view of an agricultural tractor. FIG. 2 is a plan view showing a steering device. FIG. 3 is a longitudinal sectional view showing a front wheel transmission. FIG. 4 is a linkage mechanism that links the steering device and the front wheel transmission. FIG. 5 is a cross-sectional view showing a connecting rod and a shift switching lever of a front wheel transmission. FIG. 6 is a cross-sectional view showing a switching mechanism of the front wheel transmission. FIG. 7 is a plan view showing a switching mechanism of the front wheel transmission. FIG. 8 is a longitudinal front view showing a switching mechanism of a front wheel transmission device. FIG. 9 is a plan view showing a structure when a biasing spring is attached to a linkage rod.
DESCRIPTION OF SYMBOLS 1 Front wheel 2 Rear wheel 11 Front wheel transmission 20 Friction multi-plate clutch 28 Shifting switch lever 32 Linking rod 33 Energizing spring

Claims (3)

And the standard conditions for setting the rotational speed of the front and rear wheels in the same speed, with the front wheels provide a wheel speed change device for revealing the accelerating state to rotate faster than the rear wheel speed increasing state of the front wheel transmission And a shift switching lever for operating the clutch to switch the front wheel transmission between the standard state and the acceleration state ,
A linkage rod that operates in conjunction with a steering operation in the left-right direction of the steering device that switches the advancing direction of the machine body is provided, and a through hole is formed in a connecting shaft provided in the shift switching lever, and the linkage rod is formed in the through hole The one end portion of the shift switching lever side is penetrated, the linkage rod is supported on the coupling shaft so as to be relatively movable, and the penetration shaft is configured to be able to contact the coupling shaft,
Wherein the contact between the connecting shaft of the link rod while maintaining the gear shifting lever to the standard operating position, the connecting shaft interlock the previous SL shift to the steering operation of the steering device by relative movement of the linkage rod Allow the switch lever to move to the speed increasing position,
Outside portion located between the shift switching lever is provided an urging spring for urging said acceleration operating position direction, the biasing spring and the steering device in the linkage rod the gear shifting lever was fitted to, hermetically engaging hooking one end of the gear shifting lever side of the biasing spring to the outer periphery of the connecting shaft, the other end of the biasing spring and the steering device in the linkage rod and the gear shifting lever A four-wheel drive work vehicle attached to the part located between. 2. A mechanism for adjusting a tension length of the biasing spring is provided across the other end of the biasing spring on the side opposite to the shift switching lever side and the linkage rod . Four-wheel drive work vehicle. The four-wheel drive work vehicle according to claim 1 or 2, wherein the biasing spring is constituted by a tension coil spring.

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