JPH0134005B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a release device for an automatic plowing depth control device used in an agricultural tractor, which senses the height of a working implement from the ground using a sensor and keeps the plowing depth constant.

Conventionally, as a release device for this type of automatic plowing depth control,
As shown in Japanese Patent Application Laid-open No. 55-156505, there is a device that uses a link to set the range of automatic tillage depth control, but this device has an extremely complicated structure and is difficult to use when tilling along the ridge. In order to prevent automatic plowing depth control from operating even when the sensor is on the ridge, it is necessary to set the setting lever to the maximum plowing depth. Therefore, after canceling automatic plowing depth control, it is necessary to adjust the setting lever again. It was very difficult to operate. Additionally, a device has been proposed in which a release device is installed on a link that conveys the sensing of plowing depth from the sensor side in the top link bracket, but this device also requires a complicated release link and
The control lever was located behind the driver's seat, making it difficult to operate.

Therefore, the present invention provides a stop valve in the pressure circuit,
communicating a pressure circuit to the tank through the stop valve;
It is an object of the present invention to provide a release device for an automatic plowing depth control device, which is constructed so that the pressure in the pressure circuit becomes zero by opening a stop valve, and which eliminates the above-mentioned drawbacks.

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1, the agricultural tractor 1 has a body 3 supported by wheels 2. An engine 4 is mounted on the front of the body 3, and a driver's seat is arranged at the rear. ing. Further, a position control lever 5 and a plowing depth setting lever 6 are disposed on the driver's seat, and a hydraulic case 9 in which a hydraulic block 7, a hydraulic cylinder device, and a hydraulic control valve are fixed or built-in is disposed below them. A lift arm 10 that can be rotated based on a hydraulic cylinder device protrudes from the left and right side surfaces of the case 9 and is installed therein. In addition, at the rear of the fuselage 3 there is a lower link 11 and a bracket 1 fixed to the fuselage 3.
A work implement 15 is attached to the work implement 15 by a top link 13 via the lower link 11 via the lift rod 16.
By connecting it to 0, it can be raised and lowered freely.
The working machine 15 includes a main body 17 and a rotary 19.
The rear of the rotary 19 is covered by a rear cover 20 whose upper end is pivotally supported by the main body 17. Further, the rear cover 20 is pressed downward by a spring 21, and the rotary 19
It also functions as a leveler to level the tilled soil, and also serves as a height sensor for the automatic plowing depth control device. That is, the sensor 20 is connected to a wire 25 through a rod 22 and an arm 23, and further connected to a hydraulic control valve (not shown) through a link 26 and a rod 27 provided on the bracket 12.

On the other hand, a hydraulic block 7 fixed to a hydraulic case 9 has a pump 2 installed in the engine 4 section.
Pressure oil is communicated from 9 through a pipe 30 and a joint 31, and as shown in FIG.
The block 7 has an oil passage 32 communicating with the joint 31 and a hole 33 communicating with the oil passage 32. Furthermore, the oil passage 32 has ports V and R that communicate with the hydraulic control valve and the relief valve 35, and the hole 33 has a tank port T that communicates with the tank. A bolt 36 having a hollow center is screwed into the hole 33, and a seal 37 is fitted to the tip of the bolt 36 to form a hole between the oil passage 32 and the tank port T. 33, and serves as a seat 40 for a ball 39 constituting a stop valve. Also,
A rod 41 is slidably inserted into the hollow part of the bolt 36, and the tip of the rod 41 is tapered and comes into contact with the ball 39, and the seat 40 is inserted into the hole 36a formed in the bolt 36. It communicates with tank port T via. The other end of the rod 41 is kept oil-tight by a seal 42 and protrudes from the bolt 36, and the position control lever 5 is connected via a roller 43 at the protruding end.
It is in contact with a cam 45 provided at the base end of the cam 45.
In the figure, 46 is a spring that is compressed between a washer 47 fixed to the rod 41 and the head of the bolt 36, and is used to keep the roller 43 at the end of the rod 41 in constant contact with the cam 45. Also 49
A spring is compressed between the end of the hole 33 and the ball 39, and is used to bring the ball 39 into close contact with the seat 40. Further, the cam 45 has the roller 43 located at a lower position L in the operation range P of the position control, and the cam 45 is located in the lower position L in the operation range P of the position control, and in the release range C of the position control.
It is set to be located at a high level H.

Since this embodiment has the above-described configuration, when the position control lever 5 is operated within the operating range P, the hydraulic control valve is operated to rotate the lift arm 13, and the lift arm 13 is rotated according to the operating position of the lever 5. The working machine 15 is controlled to move up and down to the desired height. Further, when the plowing depth setting lever 6 is operated, the link in the hydraulic case 9 is controlled, the rotation stroke of the link until hydraulic operation is adjusted, and the plowing depth of the automatic plowing depth based on the sensor 20 is set. When the sensor 20 rotates, for example, in the direction of arrow a with reference to the plowing depth H based on the plowing depth setting lever 6, the link 26 is rotated via the rod 22, arm 23 and wire 25, and the rod is further rotated. The hydraulic control valve is operated via 27 to operate the lift rod 10 and raise the work implement 15. Further, when the sensor 20 rotates in the opposite direction of the arrow a, the working implement 15 is lowered to the set plowing depth H along the same route as described above. In addition, in the above position control and automatic plowing depth control state, the roller 43 is moved by the cam 4 as shown in FIG.
Therefore, the ball 39 is located at the lower L of the valve seat 4.
0, and communication between the oil passage 32 and the tank pole T is cut off. As a result, the pressure oil from the pump 29 is transferred to the pipe 30 and the joint 31.
and is sent to the control valve port V communicating with the hydraulic control valve via the oil passage 32 and the relief valve port R communicating with the relief valve 35, and further sent to the hydraulic cylinder device via the hydraulic control valve. There is.

As shown in FIG. 2, when attempting to till the ridge, the sensor 20 climbs up the ridge 50 and rotates greatly in the direction of arrow a, and the automatic tillage depth control is activated to lower the work implement 15. However, at this time, as shown in FIG. 4, the position control lever 5 is rotated to the release range C. Then, the cam 45 also rotates in the direction of arrow b, and the roller 43 rides up to a higher position H on the cam 45, causing the rod 41 to slide against the spring 46. As a result, the tip of the rod 41 contacts the ball 39 and moves the ball 39 against the spring 49.
The ball 33 is separated from the valve seat 40 and the oil passage 32 is communicated with the tank port T. In this state, the pressure oil from the pump flows out to the tank port T, so the pressure in the pressure circuit becomes 0, and even if the hydraulic control valve is switched to the rising side based on the sensor 20, pressure oil does not flow into the hydraulic cylinder device. The work implement 15 is not forced to be fed, and therefore the work implement 15 does not rise, but is lowered by its gravity, and can perform ridge tillage.

As explained above, according to the present invention, the pressure in the pressure circuit 32 is reduced to zero by opening the stop valve 39.
Therefore, there is no need to cut off the sensing from the sensor 20 midway, and there is no need to install a complicated release link mechanism, etc., and the structure is extremely simple.
etc., the release operation can be performed from the driver's seat, making the operation easy.Furthermore, when releasing the release, only the stop valve 39 needs to be operated, and there is no need to operate the tillage depth setting lever 6, and the tillage depth can be reset again after release. Setting operations become extremely easy. Furthermore, if the stop valve 39 is opened by operating the position control lever 5 downward from the lowest point of the position control operation range P, a special lever is required to operate the stop valve 39. First, there is no need to increase the number of levers on the driver's seat, and operation can be simplified.

[Brief explanation of drawings]

Fig. 1 is a front view showing an agricultural tractor embodying the present invention, Fig. 2 is a front view of the working machine showing the ridge tilling operation state, and Fig. 3 is a sectional view of the hydraulic block showing the normal control state. FIG. 4 is a sectional view showing the released state. 1... Agricultural tractor, 5... Position control lever, 6... Plowing depth setting lever, 7... Hydraulic block, 15... Work equipment, 20... Sensor, 30, 32... Pressure circuit, 39... Stop valve (ball), V...control port, R...relief valve port, T...tank port.

Claims (1)

[Claims] 1. In an agricultural tractor equipped with an automatic plowing depth control device that operates a hydraulic cylinder device by operating a hydraulic control valve using a sensor that detects the height of the working device above the ground and controls the lifting and lowering of the working device, the pump communicates with the hydraulic cylinder device. An automatic plowing depth control device comprising: a stop valve provided in a pressure circuit, the pressure circuit communicating with a tank via the stop valve, and opening the stop valve so that the pressure in the pressure circuit becomes zero. release device.