JPH0473017B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a continuously variable transmission device consisting of a hydraulic pump and a hydraulic motor, which is housed in a gear transmission case, and a closed door connecting the hydraulic pump and the hydraulic motor. A short-circuit valve is provided in the middle of the connecting oil path between the hydraulic pump and the hydraulic motor, which can selectively switch the pair of connecting oil passages constituting the circuit between a communicating state and a non-communicating state. A transmission device for an agricultural tractor in which a short-circuit valve is connected to an operation mechanism of the continuously variable transmission in such a state that it is switched to the communicating state when the continuously variable transmission is switched to the neutral state. .

[Conventional technology]

In the above agricultural tractor, the short-circuit valve has conventionally been placed outside the transmission case.

[Problems to be Solved by the Invention] In the conventional device, the short-circuiting valve is attached outside the transmission case, which not only complicates the external shape of the entire device, but also requires the short-circuiting valve and the continuously variable transmission. The oil line connecting the equipment was long.

An object of the present invention is to make the entire device simple and compact, and to shorten the connection oil path between the short-circuit valve and the continuously variable transmission.

[Means for solving problems]

The present invention is characterized in that, in the above-mentioned transmission device for an agricultural tractor, the pair of pump motor connecting oil passages are connected to a partition wall between a continuously variable transmission storage space and a gear transmission storage space in the transmission case. a short-circuiting oil for connecting the short-circuiting valve and each of the pair of pump motor connecting oil passages; The reason is that a passage is bored in the partition wall, and its functions and effects are as follows.

[Effect]

By internally or perforating the short-circuit valve and the short-circuit oil passage connecting it to the continuously variable transmission in the partition wall, these will not be exposed outside the transmission case, and the continuously variable transmission will not be exposed. Avoids interference between the short-circuit valve and short-circuit oil path and the components of the continuously variable transmission or gear transmission, without having to expand the storage space as would be the case when installing the device or gear transmission inside the storage space. can. Furthermore, by providing the pump motor connection oil passage in the partition wall, the continuously variable transmission and the short-circuit valve can be connected with a short oil passage. That is, the short-circuiting oil passage connecting the pump motor connection oil passage and the short-circuiting valve can be shortened.

〔Effect of the invention〕

Therefore, the entire device can be configured simply and compactly, and can be placed even in narrow spaces.
It has become easier to arrange the device and avoid interference with other devices. Furthermore, since the oil passage can be shortened, manufacturing becomes easier in terms of oil passage formation.

〔Example〕

As shown in FIG. 7, a transmission case 3 forming the rear part of a traveling aircraft having a pair of left and right steering type front wheels 1, 1 and non-steering type rear wheels 2, 2 capable of driving each other, A riding-type agricultural tractor is constructed by attaching a lift arm 4 that connects various working devices such as a rotary tiller so that they can be raised and lowered, and a power take-off shaft 5 that transmits power to the connected working devices.

A transmission device for the front and rear wheels 1, 2 and the power take-off shaft 5 is constructed as shown in FIG.

That is, the output of the engine 6 is transmitted to the inside of the transmission case 3 via the clutch 7, the transmission shaft 8, and the input shaft 9, and this input is transmitted to the hydraulic pump 10 and the hydraulic pressure installed in the front part of the transmission case 3. The output of the transmission 12 is transmitted to the continuously variable transmission 12 which is composed of a motor 11 and can be switched between forward and forward sides with a neutral position in between. The output of the auxiliary transmission transmission is transmitted to a traveling gear type auxiliary transmission transmission mechanism (not shown) installed inside, and the output of this auxiliary transmission transmission is transmitted to a rear wheel differential mechanism (not shown) installed inside the rear part of the transmission case 3, and the transmission case 3. The transmission is branched and transmitted to a front wheel power transmission shaft 14 extending through the lower part of the front wheel. The rotational force of the input shaft 9 is transmitted to a power extraction gear transmission 16 located behind the storage space A of the continuously variable transmission 12 and housed in the transmission case 3.

To enable operation of the continuously variable transmission 12,
As shown in FIG. 2, a weight part 17 for suppressing rotational vibration caused by hydraulic pressure is attached to a transmission rotation operating shaft 18 located inside the transmission case 3, as shown in FIG. The operating pedal 21 is interlocked and connected via the swinging interlocking device 19 and the push/pull rod 20, and by depressing and operating the operating section on the front side of the machine body of this pedal 21, the machine moves forward, and the machine body of the pedal 21 moves forward. By depressing the rear side operation part, the vehicle is set to the reverse side. Then, when the roller 23 connected to the mission case 3 via the swinging arm 22 is urged against the lower end cam surface 19a of the swinging interlocking tool 19 by the spring 24, and the foot is released from the pedal 21, The rotary operation shaft 18 and the pedal 21 are configured to automatically return to the neutral position.

As shown in FIG.
A rotary short-circuit valve 25 is fitted into an assembly hole provided in a partition wall 3a between the continuously variable transmission storage space A and the gear transmission storage space B. This short circuit valve 25 connects the hydraulic pump 10 and the hydraulic motor 11 via an oil passage 27 with a throttle part 26 bored in the partition wall 3a and the internal oil passages 11a and 11b of the hydraulic motor 11, respectively.
The oil passages 28a and 28b are respectively connected to a pair of oil passages 28a and 28b bored in the partition wall 3a. As shown in FIG. 5, the rotational operating shaft 25a of the short-circuiting valve 25 is transmitted to the swinging interlocking tool 19 via the belt-type interlocking mechanism 29 and the push/pull link 30 in an enlarged manner. The continuously variable transmission 12
is operated to the forward or reverse side, the short-circuit valve 25 is closed, and the pair of pump motor connection oil passages 28a, 28b are placed out of communication so that the hydraulic motor 11 can be driven. As shown in FIG. 4, only when the continuously variable transmission 12 is operated neutrally by rotating the rotary operating shaft 18, the short-circuit valve 25 is closed. The pair of pump motor connection oil passages 28 are opened so that the short circuit oil passage 27 is opened and the hydraulic motor 11 is reliably stopped.
a, 28b are configured to be switched to communicate with each other via the oil passage 27.

[Another example]

When the short circuit valve 25 is installed inside the partition wall 3a, the partition wall 3a is installed as shown in the above embodiment.
It is advantageous to use the valve casing also as the valve casing because the valve structure can be simplified, but it may also be implemented by incorporating the valve casing together with a valve casing formed separately from the partition wall.

[Brief explanation of the drawing]

The drawings show an embodiment of the transmission device for an agricultural tractor according to the present invention, and FIG. 1 is a sectional view of the transmission;
Fig. 2 is a cross-sectional view taken along the - arrow in Fig. 1, Fig. 3 is a sectional view of the oil passage, Fig. 4 is a sectional view showing the open state of the neutral valve, and Fig. 5 is a sectional view of the continuously variable transmission operation structure. Side view, Figure 6 is a hydraulic circuit diagram for the continuously variable transmission,
FIG. 7 is a side view of the entire agricultural tractor. 3...Mission case, 3a...Partition wall, 10...Hydraulic pump, 11...Hydraulic motor,
12...Continuously variable transmission, 25...Short circuit valve,
27...Oil passage, 28a, 28b...Pump motor connection oil passage, A...Transmission storage space, B...Gear transmission storage space.

Claims (1)

[Scope of Claims] 1. A continuously variable transmission device 12 consisting of a hydraulic pump 10 and a hydraulic motor 11 is housed in a gear transmission case 3, and a pair constitutes a closed circuit connecting the hydraulic pump 10 and the hydraulic motor 11. A short circuit valve 25 that can selectively switch the connecting oil passages 28a, 28b between the hydraulic pump 10 and the hydraulic motor 11 into a communicating state and a non-communicating state in the middle of the connecting oil passages 28a, 28b. The short-circuit valve 25 is linked to the operating mechanism of the continuously variable transmission 12 in a state in which it is operated to switch to the communicating state when the continuously variable transmission 12 is switched to the neutral state. It is a transmission device of a certain agricultural tractor, and the pair of pump motor connection oil passages 28a, 2
8b is bored in the partition wall 3a between the continuously variable transmission storage space A and the gear transmission case storage space B in the transmission case 3, and the short-circuit hole 8b is formed in the assembly hole provided in the partition wall 3a. valve 2
5, and the short circuit valve 25;
A pair of pump motor connection oil passages 28a, 28b
A transmission device for an agricultural tractor in which a short-circuiting oil passage 27 connecting each of the parts is bored in the partition wall part 3a. 2 The short circuit valve 25 is connected to the partition wall portion 3a.
The transmission device according to claim 1, wherein the transmission device is fitted in a state where the valve casing also serves as a valve casing.