JPS6342658Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention enables the vehicle to travel with the transmission gear locked at a desired constant speed for work, or to drive while changing gears for non-work, such as on the road. , the driving transmission, which can freely switch forward and backward across the neutral state, is biased back to the neutral state by a biasing force that increases as the speed is increased, and the entire operating stroke on the forward side is changed to the reverse side. A speed holding member which is provided in a state that is larger than the full operating stroke and is interlocked and connected to the operating system of the transmission via a push/pull member is swingably provided, and in order to maintain the transmission in a transmission state. Regarding the driving operation structure for a work vehicle, which is provided with a friction mechanism that fixes the speed holding member and can be released freely, the purpose thereof is to configure the structure so that the restoring force of the driving transmission acts rationally on the speed holding member. By doing so, the speed can be reliably fixed, and the speed can be easily locked and unlocked.

Next, embodiments of the present invention will be described based on the drawings.

As shown in Fig. 1, a rotary tilling device (not shown) is installed at the rear of the traveling body, which has a pair of left and right steering front wheels 1, 1, driving rear wheels 2, 2, a driving section 3, etc.
An agricultural tractor, which is an example of a working vehicle, is equipped with a lift arm 4 for connecting various working devices such as the above so as to be able to be raised and lowered, and a power take-off shaft 5 for transmitting power to the connected working devices. .

In order to make it possible to stop and change the running speed of the aircraft, a hydraulic continuously variable transmission 7 is provided between the engine 6 and the rear wheels 2, which can freely switch forward and backward movement with a neutral state in between. And this transmission 7
To configure the operation structure, as shown in Figure 2,
A cam 9 that operates the swing operating member 8 of the transmission 7 by acting on its protrusion 8a is swingably attached to the transmission 7, and the biasing force increases as the operating member 8 is operated to the high speed side. spring 10,
Similarly to this spring 10, the operating member 8 is biased to contact the cam 9 by fluid pressure acting on a gear shifting swash plate (not shown) of the transmission 8, and the gear shifting is performed. The device 7 is configured to be restored and biased to a neutral position, and the cam 9
Push/pull rod 11, swing arm 12 and cylinder shaft 1
A speed change pedal 14, which is interlocked and connected via a shaft 3, is swingably attached to a support shaft 15 of the machine body through the cylindrical shaft 13. That is, when the front side operation part 14a of the pedal 14 is depressed, the transmission 7 moves to the forward side, and the rear side operation part 14b of the pedal 14 is depressed.
When the pedal 14 is depressed, the transmission 7 is set to the reverse side, and the further the pedal 14 is depressed, the more the transmission 7 is set to the high speed side, both in the forward and reverse directions.

A pair of stoppers 16a and 16b that separately determine the forward and reverse depression limits of the gear change pedal 14 are arranged such that the full operating stroke F to the forward side is greater than the full operating stroke R to the reverse side. For safety, the maximum reverse speed that can be operated is lower than the maximum forward speed.

A mechanism 17 for holding the transmission 7 in the forward transmission state against the restoring force is connected to the push/pull rod 1.
8 to the swing arm 12, and by swinging the control lever 19 of the holding mechanism 17 to the operating position (ON) while depressing the shift pedal 14, the shift pedal 14 is held at a desired operating position. You can move forward at a constant speed without any operation.
Then, move the operating lever 19 to the release position (OFF).
By switching to , the vehicle can travel while changing the speed using the speed change pedal 14 .

As shown in FIGS. 3 and 4, the holding mechanism 17 is composed of three speed holding members 20 which are slidably and rotatably connected to the push/pull rod 18 on the free end side. A case 21 fixed to the aircraft body is swingably attached to a support shaft 22 that is held unrotatably, and one piece is interposed between the speed holding member 20 and the stopper 23 or between the speed holding members 20. A plurality of friction plates 24... are slidably attached to the support shaft 22, and a spring receiver 26 is brought into contact with the side of the spring 25 opposite to the stopper 23 side.
The support shaft 22 can only slide by engaging with different diameters.
The cam 27, which is fitted onto the outside and has a concave and convex cam portion on its side surface for operating the spring receiver 26, and which connects the lever 19 to its circumferential surface, slides due to the biasing force of the spring 25. The support shaft 2 is supported by the case 21 to prevent
It is rotatably attached to 2. That is, when the operating lever 19 is switched to the operating position (ON), the cam 27 rotates, the cam convex portion rides on the side protrusion of the spring receiver 26, and the spring receiver 26 slides toward the stopper 23. The spring 25 is compressed, and the resulting elastic restoring force of the spring 25 causes the friction plate 24 to be compressed.
and the speed retaining member 20 are pressed against the stopper 23, and each speed retaining member 20 is frictionally fixed so as not to swing due to the transmission restoring force f acting on them via the push/pull rod 18. . When the lever 19 is switched to the release position (OFF), the cam 27 rotates, the cam convex part enters the recessed part on the side of the spring receiver 26, and the spring receiver 26 is slid back toward the cam 27. The friction plate 24 and the speed retaining member 20
The pressure contact with the stopper 23 is released, and the speed holding member 20 can be rotated by the transmission restoring force f.

The stopper 23 is connected to the support shaft 22 and the case 21.
The mounting position of the stopper 23 with respect to the support shaft 22 is changed by rotating a nut 28 that is configured to slide against the support shaft 22 and is attached to the support shaft 22 so as to receive and support the stopper 23. It's like this. In other words, assembly errors,
The operating position of the stopper 23 and the biasing force of the spring 25 can be adjusted so that the speed retaining member 20 is reliably fixed regardless of wear and tear of members such as the friction plate 24.

As shown in FIGS. 4 and 5, when the speed holding member 20 is at the center position m of the entire swing stroke, the swing axis X of the speed holding member 20 and the connection center P of the push/pull rod 18 are Straight line L passing through each
and the intersecting angle a with the axis B of the push/pull rod 18 is
The angle is greater than 90°, and the force required to fix the speed retaining member 20 is kept to a minimum. That is, when the transmission 7 is on the forward side, the moment M M = f x l around the axis X acting on the speed holding member 20 due to the transmission restoring force f is made as small as possible. .

More specifically, when the transmission 7 is on the low speed side, as the speed holding member 20 swings by a unit angle toward the high speed side, the increasing strength of the transmission restoring force f becomes as small as possible, and the speed change When the device 7 is on the high speed side, the arm length l is reduced as much as possible as the speed holding member 20 swings by unit angle toward the high speed side.

In addition, (Fmax), N, and (Rmax) shown in FIG. 4, FIG. 5, and FIG. 7 each indicate the position of the speed holding member 20, and (Fmax) is when the transmission 7 is at the maximum forward speed. N corresponds to when the transmission 7 is in the neutral state, and (Rmax) corresponds to when the transmission 7 is at the maximum reverse speed.

The transmission device 7 can be changed to one consisting of a belt type transmission device and a forward/reverse switching device.

In the above implementation configuration, the crossing angle a is approximately 90° when the speed holding member 20 is at the reverse maximum speed position (Rmax), but the speed holding member 20 is at the neutral state position. The intersection angle a may be configured to be 90° when the angle is at N.

In summary, the present invention provides the above-mentioned operation structure for running a working vehicle, when the speed holding member 20 is at the center position m of the entire swing stroke, the swing axis X and the The speed holding member 20 and the push/pull member 18 were connected such that the intersection angle a between the straight line L passing through the push/pull member connection center P and the axis B of the push/pull member 18 was greater than 90°. In particular, its functions and effects are as follows.

That is, conventionally, as shown in FIG. 7, when the speed holding member 20 is at the center position m of the swing stroke, the crossing angle a becomes a right angle. In this case, on the forward side of the transmission 7, the magnitude of the moment M' around the axis X that acts on the speed holding member 20 due to the transmission restoring force f is shown by the dotted line in FIG. It changes as shown in . On the other hand, in the case of the configuration of the present invention, as shown in FIG. 5, when the speed holding member 20 is at the center position m of the swing stroke, the crossing angle a is larger than 90°. Then, on the low speed side, the strength of the transmission restoring force f increasing as the speed holding member 20 swings by a unit angle toward the high speed side becomes smaller than that of the conventional configuration, and on the high speed side, the speed As the holding member 20 swings by a unit angle toward the high speed side, the decrease in the arm length l becomes larger than that of the conventional structure. Therefore, the magnitude of the moment M increases as the speed changes. It changes as shown by the solid line in Figure 6. That is, the maximum value (Mmax) of the moment M in the configuration of the present invention is smaller than the maximum value (M'max) in the conventional configuration. And in general,
Since the work is carried out while the vehicle body is moving forward, and there is no need to be able to lock the speed on the reverse side for safety reasons, the structure of the present invention allows the locking force of the friction mechanism 17 to be reduced from the conventional one. Even if the speed holding member 20 is weaker than the configuration, the speed holding member 20 can be reliably fixed at any position so as not to be returned due to the transmission restoring force 5. Therefore, it is possible to lock the speed at a desired value as reliably as in the past, and at the same time, it is possible to reduce the biasing force that is required to appear in order to operate the friction mechanism 17 to the locked state, and this biasing force. The force required to operate the friction mechanism 17 to the unlocked state against the force is smaller than that of the conventional structure, and the speed locking and unlocking operations can be performed with relatively light operating force. .

[Brief explanation of the drawing]

The drawings show an embodiment of the driving operation structure for a working vehicle according to the present invention, and FIG. 1 is a side view of an agricultural tractor, FIG. 2 is a perspective view of the transmission operation structure, and FIG. 3 is a sectional view of the friction mechanism. , FIG. 4 is a cross-sectional view taken in the direction of the - arrow in FIG. 3, FIG. 5 is a schematic side view showing the position of the speed maintaining member, and FIG. 6 is an explanatory diagram of moments.
FIG. 7 is a schematic side view showing a conventional connection structure of speed maintaining members. 7...Transmission device, 17...Friction mechanism, 18...
Push/pull member, 20...speed holding member, a...crossing angle, B...push/pull member axis, L...straight line, m...
...Central position, P...Connection center, F...Forward stroke, R...Reverse stroke, X...Rotating axis center.

Claims (1)

[Scope of utility model registration request] The traveling transmission device 7, which can freely switch forward and backward across the neutral state, is biased back to the neutral state by a biasing force that increases as the speed is set to the higher speed side, and the entire operating stroke F on the forward side is shifted to the reverse side. The transmission device 7
A speed holding member 20 is swingably connected to the operating system of the transmission device 7 via a push/pull member 18, and a release operation for fixing the speed holding member 20 is provided to hold the transmission 7 in a transmission state. The operating structure for running a working vehicle is provided with a friction mechanism 17, and when the speed holding member 20 is at the center position m of the entire swing stroke, the swing axis X of the speed holding member 20 and the pushing Pull member connection center P
For traveling of a work vehicle, the speed maintaining member 20 and the push/pull member 18 are connected such that the intersection angle a between a straight line L passing through the axis B of the push/pull member 18 is greater than 90°. Operation structure.