JPH0256272B2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention utilizes hydraulic pressure from two pumps, for example, in a power steering circuit (hereinafter referred to as a "PS circuit").
This relates to a hydraulic distribution device that distributes the hydraulic pressure between the hydraulic circuit and the working machine circuit.

(Prior art) In the conventional device shown in FIG. The entire quantity is supplied via the control orifice 4 from the first outlet port 5 to the PS circuit side leading thereto.

When the total discharge amount exceeds the control flow rate and the first pump 1 itself has not yet reached the control flow rate,
The spool 3 moves a little, keeping the A part open and opening the B part a little. As a result, a portion of the second pump 2 also flows from the second outflow port 6 to the working machine circuit side connected thereto.

When the first pump 1 alone maintains the discharge amount above the control flow rate, the spool 3 moves further to completely close the A section and open only the B section. Therefore, in this state, the entire discharge amount of the second pump 2 flows to the working machine circuit side.

(Problem to be solved by the invention) The biggest drawback of the conventional device as described above is that
This means that the B section cannot be opened wide. This is because if you try to open section B wide, you have to take a large stroke of the spool, but if you do that, the responsiveness of the spool will deteriorate.

As described above, in the conventional apparatus, since the above-mentioned section B cannot be opened to a large extent, there was a problem that the pressure loss in that section becomes large and the energy loss also becomes large.

An object of the present invention is to provide a device that minimizes pressure loss on the second pump side while maintaining good spool responsiveness.

(Means for Solving the Problems) This invention provides a first inflow port connected to a first pump, a second inflow port connected to a second pump, a first outflow port connected to a power steering circuit, etc. A main spool and an auxiliary spool are provided in the valve body, which has a second outflow port connected to a working machine circuit, etc. and a tank port connected to a tank, and first to third annular grooves are formed in the main spool. At the same time, the first annular groove and the first outflow port are communicated via a control orifice provided in the oil passage hole communicating with the first annular groove, and the first
The annular groove always communicates with the first inflow port and communicates with the tank port at the movement position of the main spool when the first pump exceeds the control flow rate, and the second annular groove always communicates with the second outflow port, and When the total flow rate of the first and second pumps exceeds the control flow rate, the third annular groove communicates with the communication passage.
It is configured to communicate with the oil passage hole through a check valve that opens due to pressure in the annular groove and to guide the oil to the communication passage side.Furthermore, a back pressure valve is provided in the flow process from the tank port to the tank, and this back pressure valve is provided in the flow process from the tank port to the tank. A pressure chamber is provided to guide the back pressure generated by the pressure valve, one end of the auxiliary spool is made to face this pressure chamber, and the auxiliary spool is moved by the pressure of this pressure chamber to communicate the second inflow port and the communication passage. It is characterized in that the second inflow port is configured to be communicated with the second outflow port via a passage different from the communication passage.

(Action of the present invention) Since the present invention is configured as described above, the first,
When the total discharge amount of the two pumps is less than the control flow rate, the entire discharge amount of the volume pumps flows out from the first outflow port.

Although the discharge amount of the first pump is less than the control flow rate,
When the total discharge amount of both pumps exceeds the control flow rate, the first pump's forward discharge and a part of the second pump's discharge amount flow out from the first outflow port,
Excess flow from the second pump flows out from the second outflow port.

Further, when the discharge amount of the first pump exceeds the control flow rate, the surplus flow rate flows out from the tank port to the tank via the back pressure valve. At this time, the pressure generated by the back pressure valve acts on the auxiliary spool, causing it to move. If the auxiliary spool moves, the second
Communication between the inflow port and the communication passage is cut off, and the second inflow port is communicated with the second outflow port via a passage different from the communication passage.

(Effects of the Invention) According to the device of the invention, the pressure loss of the second pump can be reduced without increasing the amount of overlap between the second annular groove and the communication passage. Since the amount of wrap may be small, the stroke of the main spool can be made small without impairing its responsiveness.

(Embodiment of the present invention) The valve body 7 of the embodiment shown in FIG. 2 is provided with a main spool 8 and an auxiliary spool 9.

The main spool 8 has first to third annular grooves 10 around it.
~12 is formed. The first annular groove 10 always communicates with the first inflow port 13 regardless of the moving position of the main spool 8, and also communicates with the oil passage hole 14 formed in the main spool 8. A check valve 15 is provided in this oil passage hole 14, and a control orifice 16 is provided downstream of this check valve 15. Since the first inflow port 13 is connected to the first pump 17, this first pump 17
The oil from the oil passage hole 14→control orifice 16→
PS via relay room 18 → first outflow port 19
It is made to flow to the circuit side.

The relay chamber 18 is provided with a spring 20,
The main spool 8 is maintained at the original position shown in the figure by the action of the spring 20. In this original position, the first
The annular groove 10 is at odds with the tank port 21, and the second
The annular groove 11 communicates with a second outflow port 22 leading to the working machine circuit side, is slightly offset from the communication passage 23, and closes part B thereof. Further, the third annular groove 12 wraps around the communication passage 23 to open the A section thereof.

The check valve 15 described above is incorporated into the large diameter hole 14' of the oil passage hole 14, and has a large diameter portion 24 and a small diameter portion 25.
is slidably in contact with the large diameter hole 14'. The check valve 15 configured in this manner has the third annular groove 12
Although the flow path between the oil passage hole 14 and the oil passage hole 14 is opened and closed, the pressure inside the pressure receiving chamber 26 formed around the small diameter portion 25 is
When the pressure becomes higher than the pressure inside the oil passage hole 14, the seat portion 2
Open 7. Conversely, when the pressure inside the pressure receiving chamber 26 becomes low or becomes equal to the pressure inside the oil passage hole 14, the seat portion 27 is closed.

In addition, the reference numeral 28 in the figure is a communication hole formed in the check valve 15.

The auxiliary spool 9 has first and second annular recesses 2
9 and 30, and is normally maintained at the original position shown in the figure by the action of a spring 32 within a spring chamber 31. And the spring chamber 3
A pressure chamber 33 formed at the opposite end of the pressure chamber 31 communicates with the tank port 21 through a passage 34, and a back pressure valve 36 is connected between the tank port 21 and the tank 35. Therefore, when oil flows from the tank port 21 to the tank 35, back pressure is generated at the tank port 21, and this back pressure is guided to the pressure chamber 33. When pressure acts on the pressure chamber 33, the auxiliary spool 9 moves against the spring 32.

Further, in the illustrated original position, the first annular recess 29 corresponds only to the passage 37 leading to the second outflow port 22, and communication with the second inflow port 39 connected to the second pump 38 is cut off. That is, the port 4 connecting the second inflow port 39 and the passage 37
0 is closed by the auxiliary spool 9.

Further, the second annular recess 30 has the second inflow port 3
9 and the communication passage 23, and the second
Port 4 connecting inflow port 39 and communication passage 23
The two are communicated via 0.

Next, the operation of this embodiment will be explained.

If both ports 17 and 38 are driven simultaneously and the total discharge amount is less than the control flow rate, both spools 8 and 9 are held at their original positions. In this state, the oil of the first pump 17 flows through the first inflow port 13, the oil passage hole 14, the circulation hole 28 and the control orifice 16.
It flows from the first outflow port 19 to the PS circuit via. Further, the oil from the second pump 38 flows into the pressure receiving chamber 26 through the second inflow port 39, the port 41, the communication passage 23, and the third annular groove 12, pushes the check valve 15 open, and the oil from the first pump 17 Combine with oil. That is, in this case, all of the total discharge amount of both pumps will flow to the PS circuit side.

Next, when the total discharge amount of both pumps 17, 38 exceeds the control flow rate and the individual discharge amount of the first pump 17 is less than the control flow rate, the following will occur.

In other words, when the total discharge amount exceeds the control flow rate,
A differential pressure is generated before and after the control orifice 16, and the pre-pressure is introduced into the pressure chamber 43 through the small hole 42, and the main spool 8 moves slightly against the spring 20 under the action of this pressure.

Due to this movement of the main spool 8, the second annular groove 1
1 slightly overlaps with the communication passage 23 and opens the section B. Therefore, some of the oil in the second pump 38 also flows to the second outflow port 22, supplying oil to the working machine circuit.

At this time, since the opening of the B section is small, the pressure in the pressure receiving chamber 26 is maintained at a sufficiently high level. Therefore,
Check valve 24 remains open.

Finally, when the discharge amount of the first pump 17 exceeds the control flow rate, the main spool 8 moves further, the first annular groove 10 overlaps with the tank port 21, and the surplus flow rate exceeding the control flow rate from the first pump is transferred to the tank. Return to tank 35 from port 21. At this time, back pressure is generated by the action of the back pressure valve 36, and the auxiliary spool 9 moves due to the pressure, and the first annular recess 29 moves into the second annular recess 29.
The second annular recess 30 overlaps the inflow port 39 and is offset from the second inflow port 39 .
That is, port 40 is open and port 41 is closed.

Therefore, the entire discharge amount of the second pump 38 will flow to the working machine circuit, but at this time, the auxiliary spool 9 should have a sufficient stroke and the port 40
If the actual opening area is increased, the pressure loss in that area will be reduced. In other words, the pressure loss on the second pump 38 side can be reduced without increasing the stroke of the main spool 8 in order to widen the B section.

Note that in the above state, the third annular groove 12
Since the amount of overlap between the pressure receiving chamber 26 and the communication passage 23 becomes smaller, the pressure inside the pressure receiving chamber 26 becomes lower, so that the check valve 15
closes.

At this time, if the pressure on the PS circuit side is higher than the pressure on the work equipment circuit side, the following will occur.

That is, when the discharge amount of the first pump 17 exceeds the control flow rate, the B part opens further and the pressure inside the pressure receiving chamber 26 also becomes the lower pressure of the working machine circuit, so the check valve 15 closes. Become. In other words, there is no problem that the oil from the first pump 17 flows into the working machine circuit.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is a sectional view showing an embodiment of the present invention. 7...Valve body, 8...Main spool, 9...Auxiliary spool, 10-12...1st to 3rd annular groove, 13, 3
9...First and second inflow ports, 14...Oil hole, 16...
Control orifice, 17, 38...first and second pumps,
19, 22...first and second outflow ports, 23...communication passage, 33...pressure chamber, 35...tank.

Claims (1)

[Claims] 1 a first inflow port connected to a first pump, a second inflow port connected to a second pump, a first outflow port connected to a power steering circuit, etc.
A main spool and an auxiliary spool are provided in the valve body, which has a second outflow port connected to a working machine circuit, etc. and a tank port connected to a tank, and first to third annular grooves are formed in the main spool. At the same time, the first annular groove communicates with the first outflow port via a control orifice provided in the oil passage communicating with the first annular groove, and the first annular groove always communicates with the first inflow port. , and the main spool moves to the tank port when the flow rate of the first pump reaches or exceeds the control flow rate, and the second annular groove communicates with the second outflow port at all times, and the total flow rate of the first and second pumps is controlled. When the flow rate exceeds the flow rate, the third annular groove communicates with the communication passage, and the third annular groove communicates with the oil passage hole through a check valve that opens due to the pressure action in the third annular groove. Furthermore, a back pressure valve is provided in the flow process from the tank port to the tank, a pressure chamber is provided to guide the back pressure generated by the back pressure valve, and one end of the auxiliary spool faces this pressure chamber. The auxiliary spool is moved by the pressure in the pressure chamber to block communication between the second inflow port and the communication passage, and to communicate the second inflow port to the second outflow port via a passage different from the communication passage. Hydraulic distribution device.