JPH0448327Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] This invention relates to the improvement of a diversion valve device that is used in a hydraulic circuit equipped with a plurality of hydraulic pumps such as a hydraulic excavator and divides a certain amount of oil from each hydraulic pump with priority. .

[Conventional technology]

As a conventional diversion valve device of this type,
There is one described in Publication No. 144402. As shown in FIGS. 3a to 3d, the flow diverting valve device preferentially diverts a certain amount of the pressure oil supplied to the input ports 7a and 7b to which the hydraulic pumps are connected. In a diversion valve device including a diversion port 17 and surplus ports 8a, 8b through which excess pressure oil flows out, the diversion valve has a diversion valve in which the flow rate to the diversion port 17 is compensated by the operation of spools 20a, 20b,
The two flow divider valves 2a and 2b are provided such that both ends of the respective spools 20a and 20b are opposed to each other, and are connected to each other via a spring chamber 24 into which both ends of the opposing spools are fitted and a flow divider port is opened. The spring chamber 24 is provided with a spring 23 against which the spools 20a, 20b of the two flow divider valves come into contact. This flow dividing valve device is also equipped with a directional switching valve shown at 1 in the figure, and the operation of this switching valve operates as follows.

The flow dividing valves 2a, 2b divert the pressure oil from the pump ports 7a, 7b to the surplus ports 8a, 8b and the input port 9 by switching the directional control valve 1.
It is switched and supplied to a and 9b. When the spool 3 of the directional control valve 1 is in the position shown in FIG. From 8a and 8b, each main circuit M ₁ ,
flows into M ₁ ′. The spool 3 of the directional control valve 1 is
Due to the hydraulic pressure acting on the pilot chamber 4, the
When the pump is moved to the left from the state shown in FIG. The pressure oil that has flowed into the input ports 9a and 9b is transferred to the spool 20
a, 20b, and is divided into a flow from the metering orifices 26a, 26b toward the diversion port 17 and a flow toward the surplus ports 8a, 8b.

To explain this diversion state, the hydraulic pressure P ₁₇ of the auxiliary circuit M ₂ connected to the diversion port 17 is the hydraulic pressure of the main circuits M ₁ and M ₁ ′ connected to the surplus ports 8a and 8b.
When higher than P _8a , P _8b , spools 20a, 20
Notches 20a1 and 20b1 of b are input port 9
A throttle S between a, 9b and surplus ports 8a, 8b
1, S1', and by controlling the flow rate of the flow from the input ports 9a, 9b to the surplus ports 8a, 8b by the opening area of the throttles S1, S1', the flow rate before and after the metering orifices 26a, 26b is The pressure difference is a constant pressure difference depending on the pressing force of the spring 23, and the flow rate to the branch port 17 is set to a value depending on the opening area of the metering orifices 26a, 26b. At this time, the hydraulic pressure acting on the hydraulic pump is the hydraulic pressure of the auxiliary circuit _M2 , so the hydraulic pump volumetric efficiency is the same.

In addition, the hydraulic pressure P ₁₇ of the auxiliary circuit M ₂ is connected to the main circuit M ₁ ,
When the oil pressure of M ₁ ′ is lower than P _8a and P _8b , spool 2
Notches 20a2, 20b2 of 0a, 20b connect input ports 9a, 9b and metering orifice 2.
Apertures S2 and S2' are provided between the upstream sides of 6a and 26b.
By controlling the flow rate of the flow from the input ports 9a, 9b to the branch port 17 using the opening areas of the throttles S2, S2', the differential pressure before and after the metering orifices 26a, 26b is controlled by the spring 23. A metering orifice 26 controls the flow rate to the branch port 17 with a constant differential pressure depending on the pressing force.
It is controlled to a value according to the opening area of a and 26b.

When the oil pressure P ₁₇ of the auxiliary circuit M ₂ is lower than the oil pressure P _8a , P _8b of the main circuits M ₁ , M ₁ ′, in the above operating state,
Hydraulic pressure in the main circuits M ₁ and M ₁ ' acts on each hydraulic pump. For this reason, the volumetric efficiency of the hydraulic pump on which higher oil pressure acts deteriorates, and the flow rate of the pressure oil discharged from the hydraulic pump decreases accordingly. However, for example, if the oil pressure of the main circuit connected to the surplus port 8a becomes higher than the oil pressure of the main circuit connected to the surplus port 8b,
Since the oil pressure in the pressure chamber 25a connected via the passage 22a increases, the spool 20a is pushed to the left, reducing the opening area of the throttle S2 formed by the notch 20a2. Therefore, the spring 23 is compressed, and the spool 20b moves to the left due to its pressing force, increasing the opening area of the diaphragm S2' formed by the notch 20b2. Therefore, input port 9b
This increases the flow rate from the main circuit to the branch port 17, thereby uniformly controlling the flow rate to the main circuits M ₁ and M ₁ '.

This flow divider valve device combines the spring chambers of two flow divider valves into one
Since this spring chamber is provided with one spring whose both ends abut against each spool, when one main circuit becomes higher in pressure than the other, the main circuit on the high voltage side Actuation of the spool of the diverter valve connected to the circuit presses the spool of the other diverter valve via the spring, restricting the flow to the other main circuit, regardless of the difference in pressure in the main circuit. Keep the flow rate uniform.

[Problem that the invention attempts to solve]

In the conventional switching valve device, under the condition that the directional switching valve 1 is switched and pressure oil is supplied from the branch port 17 to the auxiliary circuit, the pressures P _8a and P 8b of the surplus ports 8a and _8b are controlled.
The relationship between P17 and the pressure P17 at the branch port ₁₇ is P8a>P
When 17<P8b, for example, surplus ports 8a, 8b
Connect the left and right running circuits of the bulldozer to the shunt port 1.
When the same dozer circuit (no load) is connected to 7, when the directional control valve 1 is returned to the neutral position, the flow rate of the diversion port 17 does not return to 0, and the running speed does not return to the speed before diversion. It was found that there was a problem with the difference in speed between the left and right sides, which caused the vehicle to swerve.

The reason for this is that under the pressure condition of P _8a > P ₁₇ < P _8b , the orifices formed by the notches 20a1 and 20b1 on the surplus port side of the compensating spools 20a and 20b are fully open, that is, the spools 20a and
20b are gathered in the center, and under this condition, the directional control valve 1 is returned to neutral, and the pressure oil supplied from the pump ports 7a and 7b is directly transferred to the surplus port 8.
Even if the supply of pressure oil to the input ports 9a and 9b is cut off, there will be no change in the pressure conditions transiently. Therefore, surplus port 8
A part of the oil flowing out from a, 8b into the main circuit flows back through the notches 20a1, 20b1, and passes through the directional control valve via the restriction S2, S2' formed by the notches 20a2, 20b2 on the preferential branch side. A constant flow rate continues to flow to the branch port 17 in the same way as before returning to neutral in step 1. In other words, spool 20
The notches 20a2, 20b2 of a, 20b only function as a so-called fixed differential pressure reducing valve type flow control valve, and the high pressure surplus ports 8a, 8
Pressure oil continues to be supplied from b to the branch port 17 using the notches 20a1 and 20b1 as mere passages.

[Means for solving problems]

In this invention, the directional control valve 1 is switched and the surplus port 8 is supplied with pressure oil from the branch port 17.
The relationship between the pressures of a, 8b, and branch port 17 is P _8a
＞P ₁₇ < _P Even if the directional control valve 1 is returned to neutral and the pressure oil from the input ports 9a and 9b is cut off under the conditions of 8b, the pressure oil will not flow from the surplus ports 8a and 8b side to the branch port 17 side. The technical challenge is to prevent malfunctions that result in continuous flow of data.

The means of this invention is that, in the conventional flow divider valve device, the directional control valve is provided with a passage that directly communicates with the surplus port of the flow divider valve, and a check valve is provided between the surplus passage and the surplus port of the flow divider valve. It is characterized by having been provided.

[Effect]

According to this means (by switching the directional control valve 1)
When pressurized oil is supplied from the input ports 9a and 9b, it performs a flow dividing function like a conventional flow dividing valve device,
The surplus flow pushes open the check valve for backflow prevention and freely flows out to the surplus ports 8a and 8b.

Next, under the pressure condition of P _8a > P ₁₇ < P _8b , if pressure oil is switched to only be supplied to the surplus ports 8a and 8b without being supplied to the input ports 9a and 9b (directional switching valve 1 is set to neutral). position), the spools 20a and 20b are in a transient state where they are gathered in the center (that is, the throttles formed by the notches 20a1 and 20b1 are fully open). 20a2, 20b2
Pressure oil attempts to flow to the low-pressure diversion port 17 (via). However, since the flow of the check valve is in the opposite direction from the surplus ports 8a and 8b side (via the throttle formed by the notches 20a1 and 20b1) to the branch port 17, the check valve is closed and the flow in the opposite direction is reversed. to prevent Therefore, when the supply of pressure oil from the input ports 9a, 9b is completely cut off (by the directional control valve 1), the backflow from the surplus ports 8a, 8b is also blocked, so the supply of pressure oil cannot be switched. To reliably prevent a malfunction in which pressure oil continues to flow to the diversion port 17 after the directional control valve 1 is returned to neutral.

〔Example〕

An embodiment of this invention is shown in FIGS. 1a-c and 2. This embodiment differs from the conventional flow dividing valve device explained using FIG. 3 in that the check valves CK1 and DK
2 and passages 34a and 34b are provided.

Check valves CK1 and CK2 have surplus ports 8a and 8b.
and the surplus passages 35a and 35b. The passages 34a and 34b are connected to the pump port 7 when the switching valve 1 is in the neutral position, that is, when the flow is not divided.
a, 7b are directly connected to surplus ports 8a, 8b. The check valves CK1 and CK2 are connected to the passage 3.
4a, 34b and the surplus passage 3 of the diverter valves 2a, 2b.
Surplus passage 35 on the upstream side of the junction with 5a and 35b
a, 35b are provided with the outflow direction being the forward direction. These check valves CK1 and CK2 have springs 33a and 33
b to close the surplus passages 35a and 35b.

Since the other points are substantially the same as the conventional one shown in FIG. 3, the same parts are designated by the same reference numerals and their explanation will be omitted. Incidentally, FIG. 2 is a circuit diagram of this embodiment.

In the embodiment, check valves CK1 and CK2 prevent backflow from surplus ports 8a and 8b to branch port 17.

[Effect of idea]

According to this invention, by providing a check valve whose outflow direction is the forward direction for each surplus port of the diversion valve, surplus water is removed by backflow of pressure oil from the conventional surplus port to the diversion port. This solves the problem of the difference in speed between the left and right traveling hydraulic motors connected to the port side.

As another means for solving the above problems,
It is conceivable to provide a sequence valve or a fixed throttle on the downstream side of the branch port 17 so that the pressure relationship is always P _8a ≦P ₁₇ ≧P _8b . Even when there is no load on the downstream side of the sequence valve or fixed throttle of the side and diverter port 17, a load force due to the sequence valve or fixed throttle is generated in the pump ports 7a and 7b, resulting in large energy loss and It has a drawback that the set value of the sequence valve and the size of the fixed throttle must be changed each time depending on the flow rate of the valve 17 and the load pressure of the surplus ports 8a and 8b. On the other hand, according to this invention, the flow rate of the branch port 17 and the surplus ports 8a, 8
Regardless of the magnitude of the load pressure of b, the pressure P _8a ,
Under any pressure conditions of P ₁₇ and P _8b , it is possible not only to reliably prevent the phenomenon of backflow from the excess ports 8a and 8b to the branch port 17, but also to suppress energy loss to a negligible level.

[Brief explanation of the drawing]

Fig. 1 shows one embodiment of this invention; a is a vertical front view, b is a front view, c is a sectional view taken along the line X4-X4 in a, Fig. 2 is a circuit diagram of the same embodiment, and Fig.
The figure shows a conventional flow dividing valve device, a is a longitudinal sectional front view, and b
is a partial cross-sectional bottom view of a along the X ₁ - X ₁ line, and c is a
A partial enlarged view of the X ₂ -X ₂ cross section, d is a circuit diagram. 1... Directional switching valve, 2a, 2b... Diversion valve, 3
... Spool, 7a, 7b ... Pump port, 8
a, 8b surplus port, 9a, 9b...input port, 17...diversion port, 20a, 20b...spool, 20a1, 20a2, 20b1, 20b
2...Notch, CK1, CK2...Check valve, 23...
...Spring, 24... Spring chamber, 26a, 26b... Metering orifice, 34a, 34b... Passage, 35a, 35b... Surplus passage.

Claims (1)

[Scope of claim for utility model registration] An input port to which pressure oil is supplied, a diversion port to which a certain amount of the pressure oil supplied to this input port is preferentially diverted, and a surplus port from which excess pressure oil flows out. and configured such that the predetermined amount to be preferentially diverted is regulated by a metering orifice provided between the input port and the surplus port, and between the input port and the diversion port and the A notch forming a throttle is provided between each of the input port and the redundant port, and when the notch throttles one throttle, the other opens so that the differential pressure across the metering orifice becomes a constant value. Two flow divider valves are provided with spools that operate to compensate for the flow to the flow rate to the flow divider port, and the two flow divider valves are provided such that both ends of their respective spools are opposite to each other, and the opposite spools are connected to each other through a spring chamber into which both ends of the two flow divider valves are fitted and a diversion port is opened, and a spring is provided in the spring chamber to which the spools of the two flow divider valves abut, and each of the two flow divider valves and the two The directional control valve is provided between the pump port to which the pump is connected, and includes a spool that connects the pump port to either the input port or the surplus port of each of the two flow divider valves at the same time. In the diverter valve device, the directional switching valve is provided with a passage that directly communicates with the surplus port of the diverter valve, and a check valve is oriented between the surplus passage and the surplus port of the diverter valve. Device.