JPH045853B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a system in which the biasing force of a spring is increased by the action of secondary pilot pressure at a midway point in an oil passage that supplies pressure oil to a hydraulic clutch. A high-pass valve that opens against the pressure, a low-pass valve that closes against the urging force of a spring due to the action of the secondary pilot pressure, and an orifice are interposed in parallel to open the high-pass valve. This invention relates to a pressure control valve mechanism for a hydraulic clutch configured to set a secondary pilot pressure higher than a pilot pressure that closes a low-pass valve.

[Conventional technology]

Conventionally, in the pressure control valve mechanism of the hydraulic clutch mentioned above, spools of the same diameter were used for the high-pass valve and the low-pass valve in order to standardize the machining of the component parts and use common parts to reduce manufacturing costs. In addition to using springs with different spring constants, a predetermined pilot pressure can be set simply by using springs with different spring constants.

[Problem that the invention seeks to solve]

Although the springs used for high-pass valves and the springs used for low-pass valves have different spring constants, there is little difference in appearance, and for example, a spring for a high-pass valve can be attached to a low-pass valve. In some cases, the hydraulic clutch was assembled incorrectly, which not only caused the hydraulic clutch to malfunction, but also caused damage.

The present invention solves the above-mentioned problems of the prior art by focusing on the fact that the diameter of the spool and the diameter of the hole for inserting the spool formed in the valve body must be almost the same, and eliminates assembly errors. The purpose is to prevent.

[Means for solving problems]

A characteristic feature of the present invention for solving the above problems is that in the pressure control valve mechanism of the hydraulic clutch described above, the spring attached to the high-pass valve and the spring attached to the low-pass valve are the same spring. It consists of
The diameter of the spool of the high-pass valve is set smaller than the diameter of the spool of the low-pass valve, and this configuration provides the following effects.

[Effect]

The spring for the high-pass valve and the spring for the low-pass valve are made a common member to prevent spring assembly errors, and the diameter of the high-pass valve is made smaller than the diameter of the spool for the low-pass valve to maintain a predetermined pilot pressure. In addition, since the spool needs to fit closely into the spool insertion hole formed in the valve body, there is no possibility of incorrectly assembling spools of different diameters in the wrong position.

[Effects of the Invention] Mis-assembly of the pressure control valve mechanism can be prevented.

There is no possibility of incorrectly setting the pilot pressure.

Therefore, the hydraulic clutch will not be damaged.

〔Example〕

Figure 3 shows the transmission case M installed on the tractor.
It shows the transmission structure within, and includes the input shaft 1 and the first driving transmission shaft 2, which are interlocked and connected to the engine E.
A synchronized main gear transmission _H1 that can freely switch between four stages is provided, and a friction plate hydraulic clutch C is provided between the first transmission shaft 2 and the second driving transmission shaft 3,
A synchronized forward/reverse gear transmission H ₂ that changes the output of the second transmission shaft 3 in forward and reverse directions, a synchronized first auxiliary gear transmission H ₃ that can freely switch the output therefrom into two high and low stages, and A second auxiliary gear transmission H 4 is provided which can freely switch the output from the second gear transmission into two high and low stages, and the output of the second auxiliary gear transmission _{H 4 is} transmitted to the rear wheel 4 differential mechanism 4A and the front wheel 5. The transmission is configured to be transmitted to the differential mechanism 5A.

A synchronized gear transmission 7 is provided to change the power of the input shaft 1 into four stages and transmit it to the power output transmission shaft 6, and a relay transmission shaft is provided between the transmission shaft 6 and the power output shaft 8. 9 is provided so that the power take-off shaft 8 can be changed in speed.

Next, the speed change operation structure for the driving transmission system will be described in detail with reference to FIGS. 2 and 3.

That is, the main gear transmission H ₁ includes two main gear transmission shifters 10A, 1 that are alternatively operated.
Two operating hydraulic cylinders 11A and 11B are attached to each of which are interlockingly connected to each other, and an operating hydraulic cylinder ₁₃ which is interlockingly connected to a first auxiliary gear shifter 12 is attached to the first auxiliary gear transmission H3. It is attached.

Also, two operating hydraulic cylinders 11A, 11B for the main gear transmission _H1 and an operating hydraulic cylinder 1 for the first auxiliary gear transmission _H3 .
Three three-position switching valves S ₁ , S ₂ , and S ₃ are constructed in such a manner that the three pistons are also used as sliding spools.

The operating hydraulic cylinders 11A, 11B, 13
supply of pressure oil to and the three-position switching valve
Pressure oil is supplied to S ₁ , S ₂ , and S ₃ through the main control valve V ₁
This is done by operating a rotary type 9-position (N, F ₁ to _{F 8} ) switching valve as
Pressure oil is supplied to V ₁ from the hydraulic pump P via the pressure reducing valve 15 .

The transmission hydraulic clutch C is driven by hydraulic pressure supplied from the pressure reducing valve 15 via the pressure control valve mechanism 16, and is driven by the hydraulic pressure supplied from the pressure reducing valve 15 through the pressure control valve mechanism 1.
6 and the hydraulic clutch C, there is an alternative between a clutch engaged state in which pressure oil from the pressure control valve mechanism 16 is supplied to the clutch C, and a clutch disengaged state in which the pressure oil in the clutch C is returned to the tank T. Four pilot pressure-operated two-position switching valves 17A, 17B, 17C, and 17D are connected in series as a switching valve 17 that can be freely switched to one pilot pressure-operated two-position switching valve. 17A is pressure oil supplied from the auxiliary control valve V2, which is operated in conjunction with the manual operation lever 18 that operates the forward/reverse gear transmission _H2 and is connected in parallel to _the main control valve _V1 . The remaining three pilot pressure-operated two-position switching valves 17B, 17C, and 17D are operated by
They are operated by pressure oil supplied from the three-position switching valves S ₁ , S ₂ , and S ₃ , respectively, and the main gear transmission H ₁ , the forward/reverse transmission H ₂ , and the first auxiliary gear Only when all of the transmission H ₃ are in transmission state,
4 pilot pressure operated 2 position switching valves 17A,
When all of 17B, 17C, and 17D are switched to a communicating state, the clutch is engaged, and the clutch C is automatically switched in conjunction with a gear shift operation.

However, when one of the two hydraulic cylinders 11A, 11B of the main gear transmission _H1 is operated to the gear shifting side, the other hydraulic cylinder is operated and held in the neutral position by pressure oil. .
Further, the second auxiliary gear transmission _H4 is provided with a shifter that can be operated using a speed change lever. moreover,
The transmission device 7 relative to the power take-off shaft 8 is configured to be manually operated.

In the figure, N and F ₁ to F ₈ each indicate the operating position of the main control valve V ₁ , and F and R indicate the operating position of the auxiliary control valve V ₂ .

As shown in FIG. 1, the pressure control valve mechanism 16 includes a high-pass valve 19 that opens against the biasing force of a spring 19A under the action of a secondary pilot pressure that communicates with a hydraulic clutch C; The valve body 16 is connected in parallel with the orifice 21 and the low-pass valve 20, which closes against the biasing force of the spring 20A under the action of pilot pressure.
The spring 19A for the bypass valve 19 and the spring 20A for the low-pass valve 20 are made of the same material and have the same dimensions, and the diameter of the spool 19B for the high-pass valve 19 is the same. is smaller than the diameter of the spool 20B for the low-pass valve 20,
The predetermined pilot pressure applied to the high-pass valve 19 is set to be higher than the predetermined pilot pressure applied to the low-pass valve 20.

The pilot pressure operated switching valves 17A, 17B, 17C, which control the operation of the clutch C,
17D are automatically switched to the engaged state, pressure oil is supplied to the clutch C through the low-pass valve 20, and the piston installed in the clutch C is pressed against the friction plate in a short time.
The clutch operating pressure increases with the continued supply of pressurized oil. When this pressure rises to a predetermined pilot pressure, the low-pass valve 20 closes.
From then on, pressure oil is supplied only from orifice 21,
Pressure increases gradually.

When the pressure of the pressure oil rises to a predetermined pilot pressure that opens the high-pass valve 19, pressure oil flows in from the high-pass valve 19, and the clutch operating pressure rapidly rises to the predetermined value, so that the hydraulic clutch C is securely engaged. state.

[Brief explanation of drawings]

The drawings show an embodiment of the pressure control valve mechanism for a hydraulic clutch according to the present invention, FIG. 1 is a longitudinal sectional view showing the pressure control valve mechanism, FIG. 2 is a hydraulic system diagram for the hydraulic clutch, and FIG. It is a schematic diagram showing a transmission structure of a tractor. C... Hydraulic clutch, 16... Pressure control valve mechanism, 19... High pass valve, 20... Low pass valve, 19A, 20A... Spring, 19
B, 20B...spool, 21...orifice.

Claims (1)

[Claims] 1. A high-pass valve 19 that opens against the biasing force of a spring 19A due to the action of the secondary pilot pressure is installed in the middle of the oil passage that supplies pressure oil to the hydraulic clutch C; A low-pass valve 20 that closes against the biasing force of a spring 20A due to the action of the orifice 21
In the pressure control valve mechanism of a hydraulic clutch, the secondary side pilot pressure for opening the high-pass valve 19 is set higher than the pilot pressure for closing the low-pass valve 20. , the spring 19A attached to the high-pass valve 19 and the spring 20A attached to the low-pass valve 20 are made of the same spring, and the diameter of the spool 19B of the high-pass valve 19 is made the same as that of the spool 2 of the low-pass valve 20.
A pressure control valve mechanism for a hydraulic clutch, characterized in that the diameter is set smaller than the diameter of 0B.