JPS6218099Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an automatic neutral return device for forcibly returning the operation input shaft of a hydraulic power transmission vehicle to its neutral position.

In general, pumps and motors used in hydraulic power transmission devices are required to have high performance, so they are designed to have a structure with little internal leakage. Therefore, when the vehicle is stopped and the engine is rotating, the slight movement of the gear shift control lever, etc. will cause the hydraulic transmission's operation input shaft to involuntarily rotate slightly from its neutral position, resulting in the vehicle This causes a so-called creeping phenomenon in which the material starts to slide. If an attempt is made to forcibly stop this creeping phenomenon with a brake, the fluid pressure will increase excessively, thereby causing damage to the fluid pressure mechanism. Therefore, conventionally, in order to prevent the creeping phenomenon mentioned above, mechanisms of the operation system such as pedals and levers are used to bring out the neutral position of the operation input shaft of the hydraulic transmission. In order to ensure the neutral position of the input shaft, measures have been taken to minimize play in the operating link system and to increase the rigidity of the entire operating link system. However, with the above-mentioned conventional measures, the manufacturing cost is quite high, and the link system wears out as it is used, and the operation input shaft may not return to neutral completely even if the gear shift operation lever is moved to neutral. However, despite the above-mentioned measures, the problem still remains that the creeping phenomenon still occurs.

Therefore, in the present invention, a flat part is formed on the arm member at the operation input shaft of the hydraulic transmission device, and a pressing mechanism is configured by a spring member disposed on a support member fixed to the main body of the hydraulic transmission device. The operation input shaft of the hydraulic power transmission vehicle is configured to forcibly return the operation input shaft to the neutral position by bringing the pressing mechanism into contact with the flat surface of the arm member, thereby eliminating the above-mentioned drawbacks. The object of the present invention is to provide a shaft automatic neutral return device.

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5.

For example, a hydraulic power transmission vehicle 1 such as an agricultural tractor has a body 3 suspended by front and rear wheels 2, as shown in FIG. 1, and an engine 5 is mounted in the front part of the body 3. In the middle thereof, an operating system such as a steering wheel 6 and a speed change operation lever 7 are provided, and a seat 9 is provided at the rear thereof. In addition, a hydraulic transmission device 10 is provided at the rear lower part of the fuselage 3.
and a transmission 11 are provided. The hydraulic transmission device 10 includes an operation link system including a lever link 12, a fulcrum link 13, an operating link 16, etc., which are operated by the speed change operation lever 7, and an automatic neutral return device 17 according to the present invention connected thereto. It is now operated through the The automatic neutral return device 17 is fixed to an operation input shaft 20 protruding from the side of the main body of the hydraulic transmission 10 by an arm fixing bolt 19, as shown in FIG. 2, FIG. 3, or FIG. The hydraulic transmission device 10 includes an arm member 21 and a pressing mechanism 22 fixed to the side of the main body of the hydraulic transmission device 10. The arm member 21 has one end connected by a pin 25 to an adjuster member 23 which is screwed into the operating link 16 at the end of the operating link system, and has a flat portion 21a formed at its upper end. Further, the pressing mechanism 22 is always operated by a support member 27, a spring member 29 such as a leaf spring disposed in the support member 27, and a bottom plane 27a which is partially cut out in the support member 27. The support member 27 is configured with a flat return plate 30 that is pressed inward, and the support member 27 is configured by mounting plates 31, 31 that are integrally fixed thereto.
The hydraulic transmission device 1
It is designed to be fixed to the side of the main body. The return plate 30 is pressed against the bottom plane 27a of the support member 27 by the spring member 29, and the lower plane part 30a of the return plate 30 is connected to the upper end plane part 21a of the arm member 21. In this state, the hydraulic transmission device 10
The operation input shaft 20 is reliably positioned at the neutral position. In addition, the code 3 in Figure 2 etc.
Reference numerals 3 and 35 refer to the cover member of the pressing mechanism 22 and its fixing nut; reference numeral 36 in FIG.
3 is a lock nut of the adjuster member 23, and 39 in FIG. 3 is a hole for neutral positioning of the arm member 21 fixed to the operation input shaft 20.

Next, the assembly order of the automatic neutral return device 17 will be explained.

First, the arm member 21 is firmly fixed to the operation input shaft 20 by fitting its fitting portion into the operation input shaft 20 and tightening the fixing bolt 19 . Next, a long pin for assembly is inserted into the pin hole of the arm member 21 into which the pin 25 is inserted, and the long pin for assembly is inserted into the pin hole for neutral positioning provided on the side of the main body of the hydraulic transmission 10. It is inserted into the hole 39. In this state, the operation input shaft 20 is
is set in the correct neutral position, and the arm member 21
The upper end flat portion 21a is also positioned at a correct position corresponding to the neutral position. In this state, the position is adjusted using the elongated holes 31a, 31a so that the lower end flat part 30a of the return plate 30 of the pressing mechanism 22, which has already been separately assembled integrally, comes into even planar contact with the upper end flat part 21a of the arm member 21. At the same time, the mounting plates 31, 31 of the pressing mechanism 22 are fixed to the main body of the hydraulic transmission device 10 by bolts 32, 32. Thereafter, the long pin for assembly is removed from the pin hole into which the pin 25 is inserted, and the adjuster member 23 and the arm member 21 provided at the end of the operating link system are connected by the pin 25 and the split pin. At that time, the pin 25 can be easily moved between the adjuster member 23 and the arm member 21 when the gear shift operation lever 7 is in the neutral position.
The adjuster member 23 is adjusted relative to the operating link 16 of the operating link system by loosening the lock nut 36 so that it can be inserted into the operating link system.

Since the present invention has the above-described configuration, in the state shown in FIG. 1 in which no operating force is applied to the shift operation lever 7, that is, in the neutral state,
The return plate 30 is pressed against the bottom plane 27a of the support member 27 with an appropriate initial load by the spring force of the spring member 29, and is in a semi-fixed state.At this time, as shown in FIG. The lower end flat part 30a of the plate 30 is the upper end flat part 21 of the arm member 21.
The operation input shaft 20, which is in even planar contact with the arm member 21 and fixed to the arm member 21, is accurately positioned at the neutral position. From this state, when the shift operation lever 7 is swung in the direction of arrow A in FIG. 1, as shown in FIG. The operation input shaft 20 rotates in the direction of arrow C, the transmission device 10 operates, and the vehicle 1 moves the gear shift operation lever 7.
The vehicle starts running backwards at a speed corresponding to the swing angle. At this time, as shown by the solid line in FIG. Since the support member 27 is biased toward the bottom plane 27a of the lower end, if you release your hand from the shift operating lever 7 in this state or return the shift operating lever 7 to the neutral position, the return plate 30 will move downwards. Since the flat portion 30a returns to planar contact with the upper end flat portion 21a of the arm member 21, the operation input shaft 20 is accurately returned to the neutral position in the same manner as described above.

In the above embodiment, the pressing mechanism 22 is provided with a return plate 3.
In the embodiment, however, the return plate 30 is provided, but this is not necessarily required, and the leaf spring 29 may be in direct contact with the flat surface portion 21a of the arm member 21, or the leaf spring 29 may be in a straight line with one end fixed to the support member 27 and the other end slidably held, so that the leaf spring 29 is deflected by the rotation of the arm member 21. Also, it goes without saying that the operating link 16 may be operated not only by the operating lever 7 but also by a foot pedal.

As explained above, according to the present invention, the arm member 2 fixed to the operation input shaft 20 of the hydraulic transmission device
A pressing mechanism 22 is configured by a spring member 29 disposed on a support member 27 fixed to the main body of the hydraulic transmission 10, and the pressing mechanism 22 is connected to the arm member 21. flat part 21 of
Since the operation input shaft 20 is forcibly returned to the neutral position by contacting with a, the operation link system does not need to have a very rigid structure, and the operation link system does not become slightly distorted due to long-term use. Even if play occurs, the operation input shaft 20 of the hydraulic transmission device 10 properly returns to the neutral position, so the vehicle 1 can be reliably stopped without causing any creeping phenomenon. In addition, since the operation input shaft 20 fixed to the arm member 21 is semi-fixed at the neutral position by an appropriate initial load of the pressing mechanism 22, it is not subject to some external force unless the shift operation section 7 is operated. It does not rotate even if a load is applied, so the vehicle 1 does not start moving involuntarily, and safety can be improved.

[Brief explanation of drawings]

FIG. 1 is a side view of a hydraulic power transmission vehicle to which the automatic neutral return device for an operation input shaft according to the present invention can be applied, and FIG. 2 is a front view showing details of the automatic neutral return device for an operation input shaft according to the present invention. Figure 3 is its left side view, Figure 4
The figure shows its operating state diagram, and Figure 5 shows the X in Figure 3.
- It is a sectional view taken from the direction of the X arrow. DESCRIPTION OF SYMBOLS 1... Hydraulic pressure transmission traveling vehicle, 7... Speed change operation part (lever), 10... Hydraulic pressure transmission device, 17... Operation input shaft automatic neutral return device, 20... Operation input shaft,
21...Arm member, 21a...Plane part, 27...
...Support member, 22...Press mechanism, 29...Spring member.

Claims (1)

[Scope of utility model registration request] In a hydraulic power transmission vehicle in which a hydraulic transmission device is actuated by swinging a speed change operation part and rotating an operation input shaft, a flat part is formed on an arm member fixed to the operation input shaft, and , a pressing mechanism is constituted by a spring member disposed on a support member fixed to a main body of the hydraulic transmission device, and the pressing mechanism is brought into contact with a flat part of the arm member to forcibly move the operation input shaft. An automatic neutral return device for an operation input shaft of a hydraulic power transmission vehicle configured to position it in a neutral position.