JP4956121B2 - Steering structure of work vehicle - Google Patents

Description

  The present invention relates to a structure of a steering handle in a work vehicle.

Some agricultural tractors and riding-type rice transplanters, which are examples of work vehicles, have a structure as disclosed in Patent Documents 1 and 2 regarding a steering handle support structure.
In Patent Documents 1 and 2, the handle post (8 in FIGS. 1 and 5 of Patent Document 1) is fixed to a support case (7 in FIGS. 1 and 5 in Patent Document 1) and extended upward to operate the steering. The input shaft (7a in FIG. 1 and FIG. 7) is protruded upward from the handle post portion of the support case. A spline part is provided at the lower part of the steering shaft (FIG. 1 in Patent Document 1 and 9 in FIG. 5), and a steering handle (4 in FIG. 5 in Patent Document 1) is provided at the upper part of the steering shaft. The spline portion of the shaft and the spline portion of the steering shaft are spline-fitted, and the steering is rotatably supported on the upper portion of the handle post.

JP-A-7-10014 No. 7-50300

  In Patent Documents 1 and 2, since the handle post is fixed to the support case and extended upward, it is considered that the upper part of the handle post swings with the fixed portion with the support case as a fulcrum. As a result, a relatively large vibration is generated at the upper part of the handle post.

Thus, when the driver operates with the steering handle, for example, when the driver pushes the steering handle to the right or left side, the steering shaft is pressed from the side to the upper part of the handle post. As a result, the vibration of the upper part of the handle post may be transmitted to the steering shaft and transmitted from the steering shaft to the steering handle. In such a state, the driver with the steering wheel may feel uncomfortable, so there is room for improvement.
An object of the present invention is to reduce the state in which the vibration of the upper part of the handle post is transmitted to the steering handle via the steering shaft in the steering structure of the work vehicle.

[I]
(Constitution)
The first feature of the present invention resides in the following structure in the steering structure of a work vehicle.
Extends upwardly to secure the handle post supporting case, the protruded upward input shaft for steering operation from a portion of the handle post of the support case, the inner peripheral surface shape cylinder spline grooves are formed spline part was fixed in a state of being fitted to the lower part of the intermediate shaft, wherein to form the spline portion on one outer peripheral surface of the lower portion of the upper and the steering axis of the intermediate shaft, a cylindrical spline grooves on the inner peripheral surface is formed The spline portion is fixed to the other of the upper portion of the intermediate shaft and the lower portion of the steering shaft, and a steering handle is provided on the upper portion of the steering shaft . The spline portion is formed on the outer peripheral surface of the input shaft. the fitted spline portion of the lower portion of the intermediate shaft and splined to one of the spline of the lower portion of the upper and the steering axis of the intermediate shaft Fitted around the other of the spline portion of the lower portion of the upper and the steering axis of the intermediate shaft to the down portion Rutotomoni splined, rotatably to support the steering shaft at an upper portion of the handle post, the input The spline portion formed on the shaft is divided into an upper spline portion and a lower spline portion, and the lower spline portion of the intermediate shaft is prevented from falling between the upper spline portion and the lower spline portion with respect to the input shaft. In addition, a spline portion formed on one outer peripheral surface of the upper portion of the intermediate shaft and the lower portion of the steering shaft is divided into an upper spline portion and a lower spline portion, and between the upper spline portion and the lower spline portion. The other spline portion of the intermediate shaft and the steering shaft is prevented from coming off with respect to one of the intermediate shaft and the steering shaft. That.

(Function)
In Patent Documents 1 and 2, an input shaft for steering operation (7a in FIGS. 1 and 7 of Patent Document) is projected upward from the handle post portion of the support case, and the spline portion of the input shaft for steering operation The spline portion of the steering shaft (9 in FIG. 1 and FIG. 5 in Patent Document 1) is spline-fitted. As a result, there is a slight backlash in the spline fitting portion, so that the steering shaft is inclined with the spline fitting portion between the steering operation input shaft and the steering shaft as a fulcrum.
Therefore, in Patent Documents 1 and 2, the handle post is fixed to the support case and extends upward as described in the above-mentioned “Problem to be Solved by the Invention”. Fulcrum (the fulcrum where the upper part of the steering wheel swings) and the fulcrum of the spline fitting part between the steering operation input shaft and the steering shaft (the fulcrum where the steering shaft tilts) Are located at substantially the same position.

As a result, as described in the above-mentioned “Problem to be Solved by the Invention”, the spline fitting portion between the steering operation input shaft and the steering shaft is used as a fulcrum (a fulcrum in which the steering shaft is inclined). ), When the steering shaft is pressed to the top of the handle post from the side, the steering shaft is pressed substantially parallel to the top of the handle post, and the steering shaft is relatively wide on the top of the handle post. It is considered that the vibration of the upper part of the handle post is easily transmitted to the steering shaft.
Furthermore, since it is considered that the vibration direction of the upper part of the handle post and the vibration direction of the steering shaft are substantially matched, the vibration of the upper part of the handle post is also easily transmitted to the steering shaft in this respect. Conceivable.

  According to the first aspect of the present invention, the steering shaft includes an input shaft for steering operation, an intermediate shaft, and a steering shaft, a spline fitting portion between the input shaft for steering operation and the intermediate shaft, the intermediate shaft and the steering shaft. There are multiple spline fitting parts (for example, if there is one intermediate shaft, there are two spline fitting parts, and if there are two intermediate shafts) There are three spline fitting parts).

Thus, according to the first feature of the present invention, the spline fitting portion between the intermediate shaft and the steering shaft is more than the fulcrum of the fixed portion with the support case (the fulcrum in which the upper portion of the handle post can swing). Therefore, when the steering shaft is pressed to the upper part of the handle post from the lateral side with the spline fitting part between the intermediate shaft and the steering shaft as a fulcrum, the steering shaft is the upper part of the handle post. The steering shaft is likely to be pressed in a relatively narrow area above the handle post.
Further, since the plurality of spline fitting portions become bending points, the intermediate shaft and the steering shaft are bent into, for example, a "<", and the vibration direction of the upper portion of the handle post and the steering shaft It is difficult to match the vibration direction.

  As described above, according to the first feature of the present invention, when the steering shaft is pressed to the upper portion of the handle post from the side, the steering shaft is likely to be inclined and pressed to the upper portion of the handle post. Due to the fact that the steering shaft is likely to be pressed against a relatively small area on the upper part of the handle post and that the vibration direction of the upper part of the handle post and the vibration direction of the steering shaft are difficult to match. The vibration of the upper part of the handle post is difficult to be transmitted to the steering shaft.

According to the first feature of the present invention, since there are a plurality of spline fitting portions, the tolerance between the center of the input shaft for steering operation and the center of the steering shaft is allowed due to the play existing in the spline fitting portion. The range is large.
As a result, even when the handle post and the steering shaft are assembled, even if the support center of the steering shaft on the handle post is misaligned with the center of the input shaft for steering operation, this misalignment is absorbed by multiple spline fitting parts. Thus, the support center of the steering shaft in the handle post easily matches the center of the steering shaft.
Therefore, even when the steering shaft is not pressed from the side to the upper portion of the handle post, it is difficult for the steering shaft to come into contact with the upper portion of the handle post, and vibration of the upper portion of the handle post is not easily transmitted to the steering shaft. It has become.

(The invention's effect)
According to the first feature of the present invention, in the steering structure of a work vehicle, when the steering shaft is pressed to the upper portion of the handle post from the side, the steering shaft is pressed to a relatively small area of the upper portion of the handle post. Even in a state where the vibration direction of the upper part of the handle post is difficult to match the vibration direction of the steering shaft and the steering shaft is not pressed from the side to the upper part of the handle post. Because the steering shaft is unlikely to hit the top of the handle post, the vibration at the top of the handle post is difficult to be transmitted to the steering shaft, and the driver with the steering handle is less likely to feel uncomfortable. Was able to improve comfort.

[II]
(Constitution)
The second feature of the present invention is that the work vehicle steering structure of the first feature of the present invention is configured as follows.
It includes an O-ring abutting portion of the upper end face and lower end face of the intermediate shaft of the input shaft comprises an O-ring abutting portion of the upper end face and lower end face of the steering shaft of the intermediate shaft.

(Function)
According to the second feature of the present invention, the “action” described in the preceding item [I] is provided in the same manner as the first feature of the present invention, and in addition to this, the following “action” is provided.
Since the steering operation input shaft is linked to the steering operation transmission mechanism and the steering mechanism (manual type and power steering type), vibrations from these are easily transmitted to the steering operation input shaft.
According to the second feature of the present invention, even if vibration is transmitted to the steering operation input shaft, the steering ring is operated by the O-ring at the abutting portion between the upper end surface of the steering operation input shaft and the lower end surface of the intermediate shaft. The vibration of the input shaft is difficult to be transmitted to the intermediate shaft. Even if the vibration of the input shaft for steering operation is transmitted to the intermediate shaft, the vibration of the intermediate shaft becomes difficult to be transmitted to the steering shaft due to the O-ring at the abutting portion between the upper end surface of the intermediate shaft and the lower end surface of the steering shaft. Yes.

(Effect of the invention)
According to the second feature of the present invention, the “effect of the invention” described in the preceding item [I] is provided in the same manner as the first feature of the present invention. In addition, the following “effect of the invention” is provided. ing.
According to the second feature of the present invention, the vibration transmitted to the steering operation input shaft can be made difficult to be transmitted to the steering shaft, and the driver having the steering wheel may feel uncomfortable. It was less and the comfort could be improved.

[III]
(Constitution)
A third feature of the present invention resides in the following configuration in the steering structure for a work vehicle according to the first or second feature of the present invention.
A ring-shaped recess is formed between the upper spline portion and the lower spline portion formed on the input shaft, and spans between the ring-shaped recess and an opening formed in the spline portion below the intermediate shaft. A ball is inserted, and the ball is prevented from coming off by a ring member attached to a lower spline portion of the intermediate shaft, and an upper spline portion and a lower portion formed on one outer peripheral surface of the intermediate shaft and the steering shaft. A ring-shaped recess is formed between the spline portion and a ball is inserted between the ring-shaped recess and an opening formed in the other spline portion of the intermediate shaft and the steering shaft. Is prevented by a ring member attached to the other spline portion of the intermediate shaft and the steering shaft.

  As shown in FIG. 1, an engine 3 is provided at the front portion of the airframe supported by right and left front wheels 1, right and left and rear wheels 2, and a clutch housing 4 and a transmission case 5 are provided on the engine 3. The four-wheel drive type agricultural tractor, which is an example of a work vehicle, is connected.

  As shown in FIGS. 1 and 2, a knuckle arm 6 for steering the right and left front wheels 1 is provided, and a tie rod 7 is connected across the knuckle arms 6 of the right and left front wheels 1. A manually operated steering mechanism 8 (corresponding to a support case) is fixed to the clutch housing 4, and an operation arm 9 oscillated and driven around the horizontal axis P 1 by the steering mechanism 8 and a left front wheel 1. A steering rod 10 is connected across the knuckle arm 6.

  As shown in FIGS. 2 and 3, a cylindrical handle post 11 is provided, a bracket 11 a is fixed to the lower part of the handle post 11, and the bracket 11 a of the handle post 11 is attached to the upper part of the steering mechanism 8 by bolts 13. It is fixed. The handle post 11 extends upward, and a bracket 11b fixed to the upper portion of the handle post 11 is fixed to a support frame (not shown).

As shown in FIGS. 2, 3, and 4, the steering operation input shaft 12 protrudes upward from the upper portion of the steering mechanism 8 and enters the handle post 11. Are upper and lower Buss spline portion 12a is formed as a spline portion of the input shaft to the outer surface of the input shaft 12 for steering operation, between the upper and lower Buss spline portion 12a, a ring-shaped along the circumferential direction A recess 12b is formed, and the handle post 11 has a support center of the steering shaft 17 (the center of the cross-sectional circle of the handle post 11) and the center of the steering operation input shaft 12 so as to coincide with each other. A bracket 11 a is fixed to the upper part of the steering mechanism 8.

As shown in FIGS. 2, 3, and 4, a short intermediate shaft 14 is provided, and a cylindrical spline portion 14 a having a spline groove formed on the inner surface is fixed to a lower portion of the intermediate shaft 14, so that the spline portion 14 a Openings 14c are opened at two places. Are upper and lower Buss spline portion 14b is formed as a spline portion of the upper portion of the intermediate shaft to the top of the outer surface of the intermediate shaft 14, between the upper and lower Buss spline portion 14b, a ring-shaped along the circumferential direction A recess 14d is formed.

  As shown in FIGS. 2, 3, and 4, the spline portion 12 a of the steering operation input shaft 12 and the spline portion 14 a below the intermediate shaft 14 are spline-fitted, and the steering operation input shaft 12 and the intermediate shaft 14 are intermediate. An O-ring 19 is disposed at the abutting portion with the lower portion of the shaft 14. A ball 15 is inserted between the recess 12b of the steering operation input shaft 12 and the opening 14c of the intermediate shaft 14, and the intermediate shaft 14 is prevented from coming off from the steering operation input shaft 12. A wide ring member 16 is attached to the 14 spline portions 14a to prevent the balls 15 from coming off.

  As shown in FIGS. 2, 3, and 4, a steering shaft 17 longer than the intermediate shaft 14 is provided, and a steering handle 18 is fixed to the upper portion of the steering shaft 17. A cylindrical spline portion 17a having a spline groove formed on the inner surface is fixed to the lower portion of the steering shaft 17, and openings 17b are opened at two locations of the spline portion 17a. A cylindrical bush 20 and a seal member 21 are attached between the upper inner surface of the handle post 11 and the upper outer surface of the steering shaft 17, and the upper portion of the steering wheel 17 is rotatably supported on the upper portion of the handle post 11. ing.

  As shown in FIGS. 2, 3, and 4, the spline portion 14 b of the intermediate shaft 14 and the spline portion 17 a of the steering shaft 17 are spline-fitted, and at the abutting portion between the upper portion of the intermediate shaft 14 and the steering shaft 17, An O-ring 19 is disposed. A ball 15 is inserted across the recess 14d of the intermediate shaft 14 and the opening 17b of the steering shaft 17, and the steering shaft 17 is prevented from coming off from the intermediate shaft 14, and the spline portion 17a of the steering shaft 17 has a wide width. A ring member 16 is attached to prevent the ball 15 from coming off.

  As a result, when the steering handle 18 is rotated, the rotation of the steering handle 18 is transmitted to the steering mechanism 8 via the steering shaft 17 and the intermediate shaft 14, and the operating arm 9 of the steering mechanism 8 is moved around the horizontal axis P1. The steering rod 10 is driven back and forth, and the right and left front wheels 1 are steered left and right via the knuckle arm 6 and the tie rod 7.

  In the above structure, as shown in FIGS. 2, 3 and 4, the spline fitting portion between the spline portion 12a of the steering operation input shaft 12 and the spline portion 14a below the intermediate shaft 14, and the intermediate shaft 14, two spline fitting portions are provided such as a spline fitting portion between the upper spline portion 14 b and the spline portion 17 a of the steering shaft 17, and each of the two spline fitting portions is provided. There is a little backlash.

  As shown in FIGS. 2, 3, and 4, even if the support center of the steering shaft 17 in the handle post 11 (the center of the cross-sectional circle of the handle post 11) and the center of the input shaft 12 for steering operation are slightly shifted, Since this deviation is absorbed by the two spline fitting portions, at the upper part of the handle post 11, the support center of the steering shaft 17 on the handle post 11 (the center of the cross-sectional circle of the handle post 11) and the center of the steering shaft 17. Is easy to match. As a result, it is difficult for the upper portion of the steering shaft 17 to hit the bush 20 and the seal member 21 in the radial direction.

  As shown in FIGS. 2, 3, and 4, the spline fitting portion between the spline portion 14 b at the upper portion of the intermediate shaft 14 and the spline portion 17 a of the steering shaft 17 is attached to the bracket 11 a (the upper portion of the handle post 11). The steering shaft 17 with the spline fitting portion between the spline portion 14b above the intermediate shaft 14 and the spline portion 17a of the steering shaft 17 as a fulcrum. When the upper portion of the steering wheel 17 is pressed against the bush 20 and the seal member 21 (the upper portion of the handle post) from the side, the upper portion of the steering shaft 17 is inclined and pressed against the bush 20 and the seal member 21 (the upper portion of the handle post). The upper part of the steering shaft 17 has a bush 20 and a seal member 21 (handle post). Likely to become a state as pressed against the relatively small area of the upper).

  As shown in FIGS. 2, 3, and 4, the spline fitting portion between the spline portion 12 a of the input shaft 12 for steering operation and the spline portion 14 a below the intermediate shaft 14, and the spline above the intermediate shaft 14 In the spline fitting portion between the portion 14 b and the spline portion 17 a of the steering shaft 17, the two spline fitting portions serve as bending points, so that the intermediate shaft 14 and the steering shaft 17 can be In other words, the vibration direction of the upper part of the handle post 11 and the vibration direction of the upper part of the steering shaft 17 are difficult to match.

  As shown in FIGS. 2, 3, and 4, even when vibration is transmitted from the steering mechanism 8 to the steering operation input shaft 12, the O-ring at the abutting portion between the steering operation input shaft 12 and the lower portion of the intermediate shaft 14. Accordingly, the vibration of the input shaft 12 for steering operation is hardly transmitted to the intermediate shaft 14. Even if the vibration of the steering operation input shaft 12 is transmitted to the intermediate shaft 14, the vibration of the intermediate shaft 14 is transmitted to the steering shaft 17 by the O-ring 19 at the abutting portion between the upper portion of the intermediate shaft 14 and the steering shaft 17. It has become difficult.

[First Alternative Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention], a manually operated steering mechanism 8 is shown, but as shown in FIG. 5, a hydraulic or electric power steering operated steering mechanism 22 is provided. The present invention can also be applied to (corresponding to a support case). In this case, the structures of the intermediate shaft 14 and the steering shaft 17 are the same as those in FIGS. 2, 3 and 4, but the steering mechanism 22 extends upward from the steering mechanism 8. The post 11 and the steering shaft 17 are short.

[Second Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment of the Invention], instead of using one intermediate shaft 14, two intermediate shafts 14 are used. May be. If comprised in this way, the spline fitting part between the input shaft 12 for steering operation and the lower part of the lower intermediate shaft 14, and the upper part of the lower intermediate shaft 14 and the lower part of the upper intermediate shaft 14 Three spline fitting portions are formed, such as a spline fitting portion, a fitting portion between the upper portion of the upper intermediate shaft 14 and the steering shaft 17.
In this case, the abutting portion between the steering operation input shaft 12 and the lower intermediate shaft 14, the abutting portion between the lower intermediate shaft 14 and the upper intermediate shaft 14, and the upper intermediate shaft 14 and the steering shaft 17 What is necessary is just to arrange | position the O-ring 19 in each of butting | matching parts.

[Third Another Embodiment of the Invention]
Above Te 3, 4 and 5 odor BEST MODE FOR CARRYING OUT THE INVENTION] [First alternative embodiment of the invention] [second alternative embodiment of the invention] of the upper part of the middle between shaft 14 A cylindrical spline portion (not shown) having spline grooves formed on the inner surface is fixed, and a spline portion (not shown) is formed on the outer surface of the lower portion of the steering shaft 17 so that the intermediate shaft 14 and the steering shaft 17 You may comprise the spline fitting part between.

[Fourth Embodiment of the Invention]
In the above-mentioned [Best Mode for Carrying Out the Invention] [First Alternative Embodiment of the Invention] to [Third Alternative Embodiment of the Invention], the steering post 11 is not fixed to the steering mechanisms 8 and 22. The steering post 11 is fixed and extended upward in a transmission case (corresponding to a support case) (not shown) equipped with a transmission for transmission and a steering mechanism (not shown), and input for steering operation You may comprise so that the axis | shaft 12 may protrude from a mission case and may enter the inside of the handle post 11. FIG.
The handle post 11 is not formed in a cylindrical shape, but a bracket (portion fixed to the support case) is fixed to the lower portion of the solid support column, and a ring member (the upper portion of the steering shaft 17 is rotatable to the upper portion of the support column). The supporting part) may be fixed.
The present invention can be applied not only to agricultural tractors but also to construction machines such as riding lawn mowers, riding mowers, riding rice transplanters, combines, and wheel loaders.

Whole side view of agricultural tractor Sectional view showing inside of steering mechanism and handle post Vertical side view of the lower part of the steering wheel post, the input shaft for steering operation, the intermediate shaft, and the vicinity of the steering shaft An exploded perspective view of an input shaft, an intermediate shaft and a steering shaft for steering operation Sectional drawing which shows the inside of the steering mechanism and handle post in 1st another form of implementation of invention

8, 22 support case 11 the handle post 12 splined portion of the input shaft 12a input shaft for steering operation (upper and lower spline section)
12b Concave portion 14 Intermediate shaft 14a Lower spline portion of intermediate shaft 14b Upper spline portion of intermediate shaft (upper and lower spline portions)
14c opening
14d recess
15 balls
16 Ring member 17 Steering shaft 17a Spline portion below steering shaft
17b Opening 18 Steering handle 19 O-ring

Claims (3)

The handle post is fixed to the support case and extends upward, and the steering operation input shaft protrudes upward from the handle post portion of the support case.
A cylindrical spline portion having a spline groove formed on the inner peripheral surface is fixed in a state of being fitted to the lower portion of the intermediate shaft , and a spline portion is formed on one outer peripheral surface of the upper portion of the intermediate shaft and the lower portion of the steering shaft. In addition, a cylindrical spline portion having a spline groove formed on the inner peripheral surface is fixed in a state of being fitted on the other of the upper portion of the intermediate shaft and the lower portion of the steering shaft, and a steering handle is provided on the upper portion of the steering shaft. The spline portion formed on the outer peripheral surface of the input shaft is externally fitted with the spline portion at the lower portion of the intermediate shaft to be spline-fitted, and the spline portion at the upper portion of the intermediate shaft and the lower portion of the steering shaft is fitted with the spline portion . wherein the other of the spline portion of the top and bottom of the steering shaft of the intermediate shaft fitted to splined allowed Rutotomoni, on top of the handle post scan Rotatably to support the bearings shaft,
The spline portion formed on the input shaft is divided into an upper spline portion and a lower spline portion. The spline portion formed on one outer peripheral surface of the upper portion of the intermediate shaft and the lower portion of the steering shaft is divided into an upper spline portion and a lower spline portion, and the upper spline portion and the lower spline portion are A steering structure for a work vehicle in which the other spline portion of the intermediate shaft and the steering shaft is prevented from coming off with respect to one of the intermediate shaft and the steering shaft . Includes an O-ring abutting portion of the upper end face and lower end face of the intermediate shaft of the input shaft, the claims butt portion between the upper end face and lower end face of the steering shaft of the intermediate shaft are provided with O-ring 1 A steering structure for a work vehicle as described in 1. A ring-shaped recess is formed between the upper spline portion and the lower spline portion formed on the input shaft, and spans between the ring-shaped recess and an opening formed in the spline portion below the intermediate shaft. A ball is inserted, and the ball is prevented from coming off by a ring member attached to a lower spline portion of the intermediate shaft, and an upper spline portion and a lower portion formed on one outer peripheral surface of the intermediate shaft and the steering shaft. A ring-shaped recess is formed between the spline portion and a ball is inserted between the ring-shaped recess and an opening formed in the other spline portion of the intermediate shaft and the steering shaft. The work vehicle stearin according to claim 1 or 2, wherein a ring member attached to the other spline portion of the intermediate shaft and the steering shaft is secured. Structure.

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