JPS60533Y2 - Return oil recovery device for sub-control valves in agricultural tractors - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a return oil recovery device for a sub-control valve mounted on an agricultural tractor for operating a working machine such as a front loader mounted on the front of the tractor.

The conventional type has a hydraulic cylinder 2 as illustrated in Fig. 3.
Pressure oil is supplied from the main control valve 3, which is installed at the rear, to the sub-control valve 6 through oil pipes 8a, 8b, . Pressure oil supplied to a working machine (not shown) becomes discharged oil and returns from the sub-control valve 6 to the external oil pressure extraction lower via the return oil pipe 25, and then passes through the return oil pipe 26 to the main control valve 3.
The main control valve 3 is discharged from the main control valve 3 into the rear transmission case 10, and the transmission case 11 which is in communication with the rear transmission case 10.
At the top, there is a gear shift lever 27 for operating the gear shift mechanism.
is provided, and the outside of the base of the gear shift lever 27 passing through the transmission case 11 is covered with a serpentine 28,
The serpentine 28 is provided with a breather hole 28a that communicates with the transmission case 11, and a fuel filler port 29 and a fuel filler plug 30 are provided in the upper part of the mission case 11 in front of the shift lever 27.

When the sub-control valve 6 is operated, the pressure inside the transmission case 11 fluctuates greatly as the pressure oil moves and is discharged. It is difficult to follow the movement, and the breathing action becomes insufficient, which may cause the snake 28 to bulge out excessively.Also, since the piping of the oil pipe 25 returns to the gear shift lever 27 and is close to it, the gear shift lever 27 It may also interfere with the rocking operation.

Therefore, this idea was developed by installing a sub-control valve for operating the work equipment in front of the main control valve for supplying and discharging pressure oil to the hydraulic cylinder for lifting and lowering the ground work equipment of the tractor, and the main control valve. The discharge oil of the pressure oil supplied to this sub-control valve through the main control valve is returned to the discharge port provided at the top of the transmission case in front of the main control valve and is discharged through the oil pipe. The outlet is equipped with a breather hole that opens to the atmosphere, so that the return oil pipe for discharging oil from the sub-control valve does not interfere with the operation of the gear shift lever near the main control valve, and also allows the return oil pipe to be installed inside the transmission case. The breather hole at the outlet is designed to provide sufficient breathing action in response to severe fluctuations in pressure.

The specific structure will be explained based on one embodiment shown in the drawings. As shown in FIG. In order to supply and discharge pressure oil to the hydraulic cylinder 2,
A main control valve 3 is provided, and pressure oil from a hydraulic pump (not shown) is supplied to this main control valve 3 through an oil feed pipe 4, and the oil path of this main control valve 3 is switched using a control valve 5 to control hydraulic pressure. The bark is used to supply pressure oil to the cylinder 2 or to discharge pressure oil from the hydraulic cylinder 2.

On the other hand, a sub-control valve 6 is provided to operate the operating part of a working machine such as a front loader mounted on the front of the agricultural tractor 1, and the pressure oil from the main control valve 3 is transferred to an external part other than the hydraulic cylinder 2. The sub-control valve 6 is connected to an external oil pressure extraction lower provided for taking oil out to the sub-control valve 6 through oil feed pipes 8a, 8b, . . . .

Further, a fuel supply hole 12 as shown in an enlarged cross-section in FIG. 12 is used to recover the return oil, and a return oil cylinder 13 is provided with a hollow cylindrical mounting portion 13a large enough to fit and be inserted into the oil supply hole 12. , the discharge port 14a of the discharge pipe 14 that penetrates the outer part of the return oil cylinder 13 is connected to the inner hole 13b of the mounting cylinder part 13a.
By aligning the center of the discharge pipe 14 with the return oil cylinder 13, a narrow gap discharge port 15 is formed between the discharge port 14a and the inner hole 13b, and the outside of the return oil cylinder 13 is fixed. This return oil pipe 17 has a breather hole 13c drilled in the part thereof, and an upper end opening 13d formed in the same shape as the oil supply hole 12.
The oil supply hole cover 16 is provided so as to be elastically fitted into this upper end opening 13d.

And the return oil pipe 17 from the sub-control valve 6
For example, the oil is connected to the discharge pipe 14 via the pipe joint 18, and the main control valve 3 and the external oil pressure take-out lower are connected through oil feed pipes 19a, 19b, . . . Oil pipe 20a.

At 20b..., pressure oil is supplied and discharged by operating the operating levers 21a, 21b... of the sub-control valve 6.

Further, reference numeral 22 is a lift arm for suspending a ground work machine (not shown), and the lift arm 22 is provided so that it can be rotated up and down by the movement of the piston 23 of the hydraulic cylinder 2 in and out.

Also, the O-ring 24 inserted into the mounting cylinder 13a is connected to the oil supply hole 1.
It helps to bond closely with 2.

Therefore, pressurized oil is supplied from the sub-control valve 6 through the main control valve 3 and the external hydraulic pressure extraction lower to the operating part of the working machine (not shown) attached to the agricultural tractor 1 through any of the oil feed pipes 20a. , and the pressure oil returning from the operating section is transmitted through these oil pipes 20a...
If the sub control valve 6 is reached through either of the
The oil is discharged from the discharge port 14a of the discharge pipe 14 to the transmission case 11 via the return oil pipe 11.

Even when the amount of return oil from the sub-control valve 6 increases due to frequent operation of the operating parts of this working machine, the discharge side of the return oil pipe 17 is connected to the main control valve 3 as described above. Since the oil is returned directly to the transmission case 11 through the discharge pipe 14 without passing through the oil, the oil is discharged smoothly from the sub-control valve 6, and the returned oil does not overflow on the way. There is none.

Also, transmission case 11 and rear mission case 1
The temperature of the lubricating oil rises with the rotation of the transmission gear mechanism (not shown) installed in the transmission case, which generates gas within the transmission case and increases the internal pressure of the case. Gas and the like enter the exhaust port 15 from the oil supply hole 12 through the discharge port 14a, and are discharged into the atmosphere through the breather 13c.

During the discharge operation of this gas, for example, even if the lubricating oil in the mission case 11 enters the discharge port 14a from the oil supply hole 12 forcefully due to the gas pressure in the case, the narrow discharge port 15 will cause the lubricating oil to enter the discharge port 14a. The spouting of lubricating oil will be restricted, and some of the lubricating oil that has reached the upper return oil cylinder 13 will also remain in this return oil cylinder 13, which has a large capacity, so that only gas such as gas will flow through the exhaust hole. 13c, and there is no risk of it leaking out of the mission case 11.

In addition, in order to supply lubricating oil to the mission case 11,
When the oil supply hole cover 16 is removed, the upper end opening 13 of the oil cylinder 13 is returned.
This replenishment can be performed directly from d.

The return oil recovery device for the sub-control valve according to this invention is configured as described above, and the oil discharged from the sub-control valve 6 is drained from the upper part of the transmission case 11 in front of the main control valve 3. Since the oil is returned to the outlet 15 and discharged through the oil pipe 17, the return oil pipe 17 disposed in front of the main control valve 3 does not interfere with the operation of the gear shift lever located near the main control valve 3. This is to solve the problem of the conventional structure described above, where the return oil pipe that returns the drained oil from the sub-control valve to the main control valve prevents the operation of the gear shift lever near the main control valve. This problem could be solved by some innovation.

Furthermore, since the discharge port 15 is provided with a breather hole 13c, the large pressure fluctuations within the mission case 11 that occur due to the discharge of pressure oil when the sub-control valve 6 is operated can be absorbed by this discharge port. 15 breather hole 13c
This means that the problem can be quickly resolved, and the snakebite caused by insufficient breathing action, such as in the conventional structure where breathing action is performed by the breather hole 28a provided in the snakebite 28 of the gear shift lever 27, can be quickly resolved. The bulging phenomenon of No. 28 could be effectively prevented.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of the main part of an agricultural tractor to which the first embodiment of this invention is applied, Fig. 2 is an enlarged sectional view of the main part of this invention in Fig. 1, and Fig. 3 is a conventional agricultural tractor. FIG. 2 is a partially cutaway side view of the main parts of the tractor. Code explanation, 1... Agricultural tractor, 1...
・Hydraulic cylinder, 3...control lever,
4*8a. 8b, 19a, 19b, 20a, 20b"""oil pipe,
5...Control lever, 6...Sub control valve, 7...External hydraulic pressure outlet, 9...Engine, 10...Rear Mission case, 11...Mission case, 1
2...Oil supply hole, 13...Return oil cylinder, 1
3a...Mounting cylinder part, 13b...Inner hole,
13c...breather hole, 13d...upper end opening, 14...exhaust pipe, 14a...
・Discharge port, 15...Discharge port, 16...
Oil supply hole cover, 17...Return oil pipe, 18...
・Pipe joint, 21a, 21b... Operation lever, 2
2...Lift arm, 23...Piston, 24...01Jng.

Claims (1)

[Scope of utility model registration request] A sub-control valve for operating the work equipment is installed in front of the main control valve for supplying and discharging pressure oil to the hydraulic cylinder for lifting and lowering the ground work equipment of the tractor. The discharge oil from the pressure oil supplied to the valve is returned to the discharge port provided at the top of the transmission case in front of the main control valve and is discharged through the oil pipe. A return oil recovery device for a sub-control valve in an agricultural tractor, which is provided with a breather hole that opens.