JPH0323929B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a neutral return mechanism for an operating pedal in a tractor equipped with a hydraulic continuously variable transmission.

<Prior art> Generally, in tractors equipped with a hydraulic continuously variable transmission (hereinafter abbreviated as HST) that can switch between forward and reverse, switching and shifting are performed by depressing a pedal. A spring is usually used to return it to the neutral position.

<Problems to be Solved by the Invention> However, as shown in Figure 6, the return torque generated from the HST to the neutral position is due to the load acting on the HST (HST hydraulic pressure), the input rotation speed, etc. As a result, the force on the pedal and the feeling of the neutral brake change accordingly. This will result in

In this respect, in particular, the neutral range of the HST is quite narrow, so returning and holding the pedal stably and firmly in the neutral position is difficult due to the processing technology and assembly accuracy of the constituent parts, including the return spring, and is costly. It also gets high.

What's more, in the case of a tractor, it is normal to carry out load-bearing work in the forward direction, and load-bearing work in the reverse direction is extremely rare, and as mentioned above, under normal operating conditions, the pedals must be moved to the neutral position. Where a large moment is applied to return the pedal to its original position, conventional mechanisms of this type apply constant pressure from the return spring to the pedal, without taking into account the frequency of use of the above-mentioned load work or changes in the moment. It's just a grant.

Therefore, when going backwards during normal driving without a load, there is a risk that the aircraft will suddenly start, while when moving forward with a load, the pedals must be consciously depressed deeply, causing fatigue during use. There are problems that can easily lead to incorrect operation.

<Means for Solving the Problems> The present invention is intended to improve such problems, and for this purpose, an integrated structure is installed on the operating shaft of the HST mounted on the tractor body, using this as a swinging fulcrum. an actuation arm rotatably mounted; a pedal pivotally connected to the actuation arm by a rod; The arm is pivoted to the fuselage so as to swing around the swinging fulcrum of the arm support shaft, which is also parallel to the operating axis, and is provided with an adjustment arm for returning to neutrality, which is constantly applied with spring pressure in the direction of returning the pedal to neutrality. In a tractor equipped with a hydraulic continuously variable transmission, there is a large-diameter idler roller for forward control that comes into contact with the adjustment arm when the machine moves forward by pressing the pedal, and a reverse roller that also comes into contact with the adjustment arm when the machine moves backward. A pair of small-diameter rocking rollers for control are placed in a vertical positional relationship sandwiching the rocking fulcrum of the operating arm, and when the pedal is in the neutral position, the pair of these two rollers simultaneously come into contact with the adjusting arm. , are each pivoted to the operating arm, and the mutual distance between the pivot point of the forward control idler roller and the pivot point of the adjustment arm is also determined by the pivot point of the adjustment arm and the pivot point of the backward control idler roller. The spring pressure in the neutral return direction that acts on the forward control idler roller during the forward operation of the aircraft is also applied to the backward control idler roller during the reverse operation of the aircraft. It is characterized by a difference that has been changed to become weaker than that.

<Example> Hereinafter, the specific configuration of the present invention will be described in detail based on the illustrated example. FIGS. An HST (not shown) is incorporated into the transmission system for the rear wheels inside the transmission case. Reference numeral 11 denotes an operating shaft which extends horizontally from the HST to the outside of the fuselage 10 and is suspended, and an operating arm 12 that rotates the operating shaft 11 integrally is attached and fixed to the extended end of the operating shaft. The actuating arm 12 is configured to swing in the front-rear direction with its midway portion serving as a swinging fulcrum A by the actuating shaft 11.

Reference numeral 13 denotes a pedal for switching between forward F and reverse R, which is connected to a seesaw via a swing lever (not shown) around a pedal support shaft 14 that protrudes from the aircraft body 10 in a fixed state parallel to the operating shaft 11. It is pivoted so that it swings as if the aircraft 10 moves forward F.
At times, the front position is stepped downward, and when moving backward R, the rear position is stepped downward. 1
5 is the middle part of the pedal 13 and the above-mentioned operating arm 1
It is a rod of a certain length that pivotally connects the lower part of the rod 2 and the lower part of the rod 2, and although the details are not shown, the length can be adjusted in advance to make it longer or shorter.

Further, reference numeral 16 denotes a large-diameter idler roller 17 for forward control, which is pivotally supported at the upper position of the operating arm 12.
are also small-diameter rocking rollers for backward movement control that are pivotally supported at the lower part of the operating arm 12, and a pair of these rollers are vertically opposed to each other across the swinging fulcrum A of the operating arm 12. In this state, when the pedal 13 is in the neutral position N, it is designed to simultaneously come into contact with an adjustment arm for returning to neutrality, which will be described later, as shown in FIG.

In that case, the mutual distance b between the pivot point B of the forward control idler roller 16 and the swing support point A of the actuating arm 12 is the same as the mutual distance b between the pivot point A and the pivot point C of the reverse control idler roller 17. Although it can be set to be substantially the same as the distance a, in particular, in the illustrated example, the amount of expansion and contraction of the neutral return spring mentioned above or the amount of rocking of the adjustment arm pulled by the spring can be set to be the same as the amount of movement during the forward F operation and the reverse R operation. In order to keep the distances b equal to each other, the distance b of the former is set to be longer than the distance a of the latter.

Further, reference numeral 18 is an adjustment arm for returning to neutrality, which is bent into an L shape, and is adjusted from the fuselage 10 at the boundary position between the upright half 19 and the almost horizontal other half 20. Above pedal shaft 1
The arm support shaft 21 is protruded in a fixed state similar to 4.
It is pivoted to. The support shaft 21 is also parallel to the operating shaft 11 of the HST, and is connected to the swing support D.
The adjustment arm 18 is designed to perform a swinging motion. 22 is the other half 20 of the adjustment arm 18
This is a tension coil spring for returning to neutrality which is connected and tensioned between the adjusting arm 18 and the fuselage 10, and constantly presses and urges the middle half 19 of the adjusting arm 18 forward.

In that case, especially one half 19 of the adjustment arm 18 which was in charge of the pushing elastic force in the direction of return of the neutral N.
are both idler rollers 16 of the operating arm 12,
17, and is set to be in equal contact with both idler rollers 16 and 17 at the same time and at the same time in the neutral N state.

Furthermore, the mutual distance y between the swing fulcrum D of the adjustment arm 18 and the shaft fulcrum B of the forward control idler roller 16 is the same as the mutual distance y between the swing fulcrum D and the shaft support C of the reverse control idler roller 17. Although a common coil spring 22 for returning to neutral is used, its return pressing force is adjusted by the adjustment arm 18 so that it is weaker than the idler roller 16 for forward control, and is used for reverse control. The idler roller 17 can be strongly operated.

That is, when the aircraft 10 is operated forward F and backward R, the same neutral return pressing force is applied by the coil spring 22, and the above-mentioned pressure on both the idler rollers 16 and 17 is applied so that the amount of expansion and contraction of the coil spring 22 is the same. In addition to determining the dimensional ratio of the interval distances x and y, the length of the other half 20 connecting the attachment point E of the coil spring 22 to the adjustment arm 18 and the swinging fulcrum D of the adjustment arm 18 is defined as z, and the above interval distance is determined. If w is the load when the coil spring 22 has a constant working length L from the dimensional ratio of x and y, the force acting on the forward control idler roller 16 and the reverse control idler roller 17 has the following relationship. It is set to maintain the .

Forward (F) operation W・Z/y < W・Z/x For reverse (R) operation In addition, regarding the load w, the minimum load during forward F operation, that is, the operating shaft 11 of HST is on the speed increasing side. It goes without saying that the return spring load should be set in advance to a value that provides a good neutral brake feeling, as the return spring load is greater than the shaft torque value that acts toward the brake.

In this regard, in the basic embodiment shown in FIGS. 2 to 4, the adjustment arm 18 itself is defined as an L-shaped bent type, but if the configuration does not deviate from the above spirit, the modification shown in FIG. As shown in the example, the adjustment arm 18 may be formed in a straight I-shape, or in other shapes.

<Function> Based on the basic embodiment described above, the following function will be explained. When the front part of the pedal 13 is depressed, the lower part of the actuating arm 12 is moved by the rod 15 as shown in FIG. Idler roller 1 for forward control, which is pulled forward by
6 is in contact with the adjustment arm 18 and receives the return pressure in the neutral direction by the coil spring 22, and the HST maintains the forward speed state F according to the amount of depression of the pedal 13. In this case, the return pressure acting on the forward control idler roller 16 is relatively weak due to the above-mentioned configuration, so that the speed can be easily changed during frequently used forward load work.

Conversely, when the rear part of the pedal 13 is depressed, the lower part of the operating arm 12 is pushed rearward by the rod 15, as shown in FIG. Only the roller 17 is in contact with the adjustment arm 18, also the coil spring 2
2 to return to the neutral direction, and the HST is maintained at a speed state of reverse R according to the amount of depression of the pedal 13. Under this condition, the return pressure applied to the movement control idler roller 17 is strong as described above, so that sudden start in the backward direction during normal running can be prevented.

In the neutral N state where the depression is completely released, the adjustment arm 18 is attached to both the forward control and reverse control idler rollers 16, 17 under the so-called two-point support action, as shown in FIG. comes into contact with
Since a constant acting force of the coil spring 22 is applied to this, an extremely stable and firm posture of the pedal 13 can be obtained, and it is possible to cope with the extremely narrow neutral range of the HST. In any case, the idler roller 16 for forward control and the idler roller 17 for reverse control are pivotally supported on the actuating arm 12 so that they can freely freely move, and come into contact with the adjustment arm 18 during their idle movement. As a result, it is possible to effectively eliminate uneven wear, sliding resistance, shock, etc. caused by the contact action, and not only its durability but also the smoothness and stability of the above-mentioned gear shifting action are significantly improved. It is possible to subaru.

Furthermore, when working with the tractor body 10, the forward control idler roller 16 is used more frequently than the reverse control idler roller 17; Since they are formed in large dimensions, the above-mentioned functions can be achieved without any problems, while the durability and cost of the two idler rollers 16 and 17 can be rationally balanced.

<Effects of the Invention> As described above, in the present invention, the tractor body 10
An operating arm 12 is attached to the operating shaft 11 of the HST mounted on the HST so that it can rotate integrally with this as a swinging fulcrum A, and the operating arm 12 swings around a pedal support shaft 14 parallel to the operating shaft 11. A pedal 13 is pivotally attached to the body 10 and pivotally connected to the actuating arm 12 and a rod 15, and a pedal 13 is also pivoted to the body 10 around a swing fulcrum D of an arm support shaft 21 parallel to the actuating shaft 11. In a tractor equipped with a hydraulic continuously variable transmission, which is equipped with a neutralization adjustment arm 18 which is pivotably mounted to move the pedal 13 and is constantly applied with spring pressure in the direction of returning the pedal 13 to neutrality, when the pedal 13 is depressed. A large-diameter idler roller 16 for forward control that comes into contact with the adjustment arm 18 during forward operation of the fuselage 10;
The small-diameter idler rollers 17 for reverse control that come into contact with the adjustment arm 18 during reverse operation are arranged as a pair in a vertical position relationship sandwiching the swing fulcrum A of the operating arm 12, and when the pedal 13 is in the neutral position. The two pairs are each pivoted on the operating arm 12 so that they come into contact with the adjustment arm 18 at the same time, and the pivot point B of the forward control idle roller 16 and the swing support point D of the adjustment arm 18 are Mutual spacing distance y
is also set to be longer than the mutual distance x between the swing fulcrum D of the adjustment arm 18 and the pivot point C of the idle roller 17 for backward motion control, and the idle roller 16 for forward motion control when the body 10 is operated forward Since the spring pressure acting in the direction of returning to neutrality is changed to be weaker than the spring pressure acting on the backward control idler roller 17 during the reverse operation of the aircraft 10, the This has the effect of reliably improving the problems of the prior art mentioned at the beginning.

That is, according to the configuration of the present invention, the actuating arm 12
A pair of forward control idler rollers 16 and reverse control idler rollers 17 are pivotally supported at both end positions, and when the pedal 13 is in the neutral position N, the operating arm 12 swings as shown in Fig. 2. Since the pair of two pieces in the vertical positional relationship sandwiching the fulcrum A come into contact with the adjustment arm 18 at the same time,
Even for the narrow neutral range of HST, the pedal 1
3 as an accurate neutral return state, which has the effect of being able to be held stably and firmly at all times.

Furthermore, since the neutral state of the pedal 13 is maintained by bringing the pair of floating rollers 16 and 17 into contact with the adjustment arm 18 at the same time, the load of the neutral return spring 22 acting on it is also reduced individually. This also helps improve durability.

Furthermore, since both of the floating rollers 16 and 17 come into contact with the adjustment arm 18 as literal floating rollers, they are more effective than those using fixed pins or other rigid members that do not swing. , according to the swinging motion of the actuating arm 12 during forward/reverse operation as shown in FIGS. 3 and 4.
Each of the floating rollers 16 and 17 moves smoothly and follows the adjustment arm 18, and due to the contact action with the adjustment arm 18, the sliding resistance, shock, uneven wear, etc. can be effectively eliminated, resulting in highly reliable durability. This means that a rich configuration can be easily obtained.

Moreover, since the idler roller 16 for forward control is made to have a larger diameter than the idler roller 17 for reverse control, even though stable contact action can be obtained as described above, it is difficult to work with the tractor. Moreover, the durability of the forward control idler roller 16, which is frequently used, can be significantly improved.

In particular, in the case of the present invention, the idler roller 1 for forward control
The distance y between the pivot point B of the adjustment arm 18 and the pivot point D of the adjusting arm 18 is the same as the pivot point D of the adjustment arm 18 and the pivot point C of the backward control idler roller 17.
The spring pressure in the neutral return direction acting on the forward control idler roller 16 during the forward operation of the tractor body 10 is weak, and the spring pressure in the direction of neutral return is also weak during the backward operation. Since the force acting on the backward control idler roller 17 is changed to be stronger, when the tractor body 10 is being used for forward load work, it is possible to shift gears without fatigue by lightly depressing the pedal 13. During normal driving in reverse, the pedal 13 naturally becomes heavier and the risk of sudden start can be reliably prevented.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of a tractor according to the present invention, Fig. 2 is an enlarged side view of the tractor in a neutral operating state, with its main parts extracted and schematically extracted, and Figs. 3 and 4 are similarly in forward operating state and reverse operating state. FIG. 5 is an enlarged side view of a modified embodiment corresponding to FIG. 2, and FIG. 6 is a line graph showing the return torque acting on the operating shaft of the HST. 10... Tractor body, 11... Operating shaft, 1
2... Operating arm, 13... Pedal, 14... Pedal support shaft, 15... Rod, 16... Idle roller for forward control, 17... Idle roller for reverse control, 18... Adjustment arm, 21... arm support shaft,
22... Coil spring, A, D... Swinging fulcrum, B,
C... Axis fulcrum, E... Spring attachment point, a, b... Interval distance, x, y... Interval distance.

Claims (1)

[Scope of Claims] 1. An operating arm 12 that is attached to the operating shaft 11 of the HST mounted on the tractor body 10 so as to be able to rotate integrally with this arm as a swing branch A, and an operating arm 12 parallel to the operating shaft 11. A pedal 13 is pivotally mounted to the body 10 so as to be able to swing around a pedal support shaft 14 and is pivotally connected to the actuation arm 12 by a rod 15; A hydraulic continuously variable transmission equipped with an adjusting arm 18 for returning to neutral, which is pivotally mounted to swing around a swing fulcrum D of a shaft 21, and is constantly applied with spring pressure in the direction of returning the pedal 13 to neutral. In the mounted tractor, a large-diameter idler roller 16 for forward control that comes into contact with the adjustment arm 18 when the machine body 10 is operated forward by pressing the pedal 13, and
The small-diameter idler rollers 17 for reverse control that come into contact with the adjustment arm 18 during reverse operation are arranged as a pair in a vertical position relationship sandwiching the swing fulcrum A of the operating arm 12, and when the pedal 13 is in the neutral position. The two pairs are each pivoted on the operating arm 12 so that they come into contact with the adjustment arm 18 at the same time, and the pivot point B of the forward control idle roller 16 and the swing support point D of the adjustment arm 18 are Mutual spacing distance y
is also set to be longer than the mutual distance x between the swing fulcrum D of the adjustment arm 18 and the pivot point C of the idle roller 17 for backward motion control, and the idle roller 16 for forward motion control when the body 10 is operated forward A fluid type continuously variable transmission characterized in that the spring pressure acting in the neutral return direction is changed so as to be weaker than the spring pressure acting on the backward control idler roller 17 during the backward operation of the aircraft body 10. Neutral return mechanism for operating pedals on tractors mounted on aircraft. 2 Mutual distance b between the swing fulcrum A of the operating arm 12 and the pivot fulcrum B of the forward control idler roller 16
is also set to be longer than the mutual distance a between the swinging fulcrum A of the operating arm 12 and the pivoting fulcrum C of the backward control idler roller 17, so that the adjustment arm 18 when the aircraft 10 is operated forward.
An operation pedal for a tractor equipped with a hydraulic continuously variable transmission according to claim 1, characterized in that the amount of rocking of the vehicle body 10 is substantially equal to that when the vehicle body 10 is operated in reverse. neutral return mechanism.