JPS6319605Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a hydraulic distribution device that distributes pressure oil to, for example, a power steering circuit and a working machine circuit, respectively.

(Prior Art) As this type of device, the one shown in FIG. 1 has been known in the past.

The apparatus shown in FIG. 1 includes a valve body 1, a first
2 inlet ports 2, 3, tank port 4 and 1st,
Two outflow ports 5 and 6 are formed.

and the pump P ₁ is connected to the first inlet port 2,
The pump P ₂ is connected to the second inlet port 3 and the tank port 4 is connected to the tank 7 . The first outflow port 5 communicates with a power steering circuit (not shown), and the second outflow port 6 communicates with a working machine circuit.

Both ends of the valve body 1 constructed as described above are plugged with plugs 8 and 9, and a spool 10 is slidably provided within the body 1.

The spool 10 has first to third annular grooves 11 to 1.
3, and an oil passage hole 14 that communicates with the first and third annular grooves 11 and 13 is formed along the axis. This oil passage hole 14 communicates with a relay chamber 16 via a control orifice 15 formed at the end of the spool 10.

A spring 17 is provided in the relay chamber 16,
The spool 10 is normally held in its original position as shown.

The first annular groove 11 always communicates with the first inflow port 2 regardless of the moving position of the spool 10. Further, when the spool 10 moves within a predetermined range against the spring 17, this first annular groove 11 also communicates with the tank port 4, and the first inflow port 2
and the tank port 4 are connected to each other.

The second annular groove 12 is always connected to the second outflow port 6
While the spool 10 is connected to the spring 17
When the second inflow port 3 moves slightly against the
The second inflow port 3 and the second outflow port 6 are in communication with each other.

The third annular groove 13 communicates with the second inlet port 3 when in the original position shown, but when the spool 10 moves against the spring 17, the third annular groove 13 communicates with the second inlet port 3. I have to.

However, when the two pumps P ₁ and P ₂ are driven simultaneously, the oil from both pumps P ₁ and P ₂ passes through the oil passage hole 14 and the control orifice 15 .
When oil passes through the control orifice 15, a differential pressure is generated before and after the orifice 15, and this prepressure flows into the pressure chamber 19 through the small hole 18 and acts on the end surface of the spool 10. As the discharge amount of the pump increases and the pressure difference across the control orifice 15 increases, the amount of movement of the spool 10 also increases, but the relationship with each port during the movement process of the spool 10 is as follows. It is.

That is, when the total discharge amount of both pumps is equal to or less than the control flow rate in the illustrated state, the spool 10 maintains the illustrated state. Therefore, the entire amount of oil from both pumps P ₁ and P ₂ flows out from the first outflow port 5,
Reach the power steering circuit.

Further, when the discharge amount of pump _P1 is less than the control flow rate and the total discharge amount of both pumps slightly exceeds the control flow rate, the differential pressure across the control orifice 15 becomes slightly large and the spool 10 begins to move. In this state, the second annular groove 12 and the third annular groove 1
3 are in a relationship that communicates with the second inflow port 3 little by little. Therefore, the total output of pump P ₁ and a part of the output of pump P ₂ flow out from the first outflow port 5, but the remaining output of pump P ₂ flows out from the second outflow port 6 and is used for work. Reach the machine circuit.

Furthermore, when the discharge amount of the pump P ₁ exceeds the control flow rate, the spool 10 moves further than described above, and the second inflow port 3 is disconnected from the third annular groove 13 and communicates only with the second annular groove 12. I will do it. Therefore, the entire discharge amount of the pump P ₂ will flow into the working machine circuit from the second outlet port 6.

Then, after the discharge amount of the pump _P1 reaches the control flow rate, the first annular groove 11 also communicates with the tank port 4 at a slightly delayed timing. Therefore, the surplus flow rate exceeding the control flow rate of pump _P1 is returned to tank 7.

(Problems to be Solved by the Present Invention) The conventional device described above has the following disadvantages when the pressure on the power steering circuit side is higher than the pressure on the working machine circuit side.

In other words, if the discharge amount of the pump P ₁ exceeds the control flow rate and the third annular groove 13 and the second inflow port 3 are in communication even a little before the tank port 4 is opened as described above, the pump P The surplus flow rate of ₁ is
It flows from the third annular groove 13 via the second inflow port 3 to the second annular groove 12, and from this second annular groove 12 it flows via the second outflow port 6 to the working machine circuit side. When the surplus flow rate of the pump P ₁ flows to the working machine circuit side in this way, there is a problem in that the load on the pump P ₁ increases accordingly.

In addition, in order to eliminate the above drawbacks, the spool 10
It is also conceivable to make the stroke of the pump extremely small so that the amount of overlap between the third annular groove 13 and the second inflow port 3 becomes zero at the same time as the pump _P1 reaches the control flow rate.

However, reducing the stroke of the spool 10 in this way means that the second and third annular grooves 12,
The maximum amount of overlap between P 13 and the second inlet port 3 also becomes smaller, and the pressure drop between the pump P ₂
energy loss becomes large.

This invention aims to provide a device that minimizes energy loss even when the pressure on the first outflow port side connected to the power steering circuit etc. is higher than the pressure on the second outflow port side connected to the work equipment circuit etc. purpose.

(Means for Solving Problems) In order to achieve the above object, this invention includes a check valve in the oil passage hole that opens and closes the flow path between the oil passage hole and the third annular groove, and A pressure receiving chamber is formed around the check valve and constantly communicates with the third annular groove, and when the pressure in the pressure receiving chamber is equal to or lower than the pressure in the oil passage hole, a flow path between the oil passage hole and the third annular groove is formed. It is configured to close.

(Operation of the present invention) With the above structure, when the pressure on the first outflow port side, which is the pressure on the oil passage hole side, is higher than the pressure on the second outflow port side, which is the pressure on the pressure chamber side, , the check valve closes. Therefore, the pressure oil in the first inflow port that has flowed into this oil passage hole does not flow out from the second outflow port.

When the pressure on the oil passage hole side becomes lower than the pressure on the pressure chamber side, the check valve opens and the oil passage hole and the third annular groove are brought into communication. When the two communicate with each other in this manner, a portion of the pressure oil supplied to the oil passage hole flows toward the second outflow port.

(Embodiment of the present invention) The embodiment shown in FIG. 2 will be described below, and the above description will be used for the same parts as the conventional device shown in FIG. 1.

The embodiment shown in FIG. 2 is the greatest improvement over the conventional device in that a check valve 20 is provided in the oil passage hole 14 of the spool 10.

In other words, a large diameter hole 14' is defined in the oil passage hole 14 from a portion slightly upstream of the portion corresponding to the third annular groove 13 to the control orifice 15, and a large diameter hole 14' is formed at the boundary of the large diameter hole 14'. The stepped portion serves as a seat portion 21.

A check valve 20 is provided in this large diameter hole 14', and this check valve 20 consists of a large diameter part 22 and a small diameter part 23, and this large diameter part 22 can be freely slid into the large diameter hole 14'. It is brought into contact with Further, this check valve 20 is formed with a communication hole 24 having the same axis as the oil passage hole 14, and the tip of the small diameter portion 23 is normally brought into pressure contact with the seat portion 21 by the action of a spring 25. Check valve 2
0 is in pressure contact with the seat portion 21 in this manner, a pressure receiving chamber 26 communicating with the second inflow port 3 is formed around the small diameter portion 23.

Therefore, the pressure from the pump _P2 is introduced into the pressure receiving chamber 26, but the check valve 2 at this time
The pressure receiving area of 0 is the cross-sectional area of the large-diameter hole minus the cross-sectional area of the oil passage hole, and the check valve 20 is activated when the pressure inside the pressure receiving chamber 26 is equal to or lower than the pressure inside the oil passage hole 14. It is configured to close.

However, when the total discharge amount of both pumps P ₁ and P ₂ is less than the control flow rate, the spool 10 maintains the original position shown in the figure, and the pressure inside the pressure receiving chamber 26 also increases.
The check valve 20 opens and the entire discharge of both pumps P ₁ and P ₂ flows to the power steering circuit.

When the total discharge amount of both pumps P ₁ and P ₂ exceeds the control flow rate and the discharge amount of pump P ₁ is less than the control flow rate, the spool 10 moves slightly against the spring 17 and the second annular groove 12 and the second inflow port 3 are in slight communication with each other.

At this time, the pressure on the power steering circuit side is
Even if the pressure is higher than the pressure on the work equipment circuit side, the second annular groove 1
2 and the second inflow port 3, the pressure within the pressure receiving chamber 26 is maintained high and the check valve 20 remains open.

In other words, a part of the discharge amount of the pump _P2 flows to the working machine circuit side, but most of it flows to the power steering circuit side.

When the pump P ₁ alone secures the controlled flow rate in the above state, the spool 10 moves further, and the amount of overlap between the second annular groove 12 and the second inflow port 3 becomes even larger. If the amount of wrap increases in this manner, the pressure within the second inflow port 3 will become equal to the pressure on the working machine circuit side.

If the pressure on the working machine circuit side is lower than the pressure on the power steering circuit side at this point, the pressure in the pressure receiving chamber 26 is lower than or equal to the pressure in the oil passage hole 14. Therefore, the check valve 20 is pressed against the seat portion 21 by the action of the spring 25, and communication between the second inflow port 3 and the oil passage hole 14 is cut off.

Since the communication between the two is cut off as described above, the oil discharged from the pump _P1 will not flow to the working machine circuit side.

Note that when the pressure on the working machine circuit side is high, the check valve 20 closes as the amount of overlap between the third annular groove 13 and the second inflow port 3 decreases.

(Effects of the present invention) According to the hydraulic distribution device of this invention, when the pressure on the first outflow port side is higher than the pressure on the second outflow port side, the oil in the oil passage hole passes through the third annular groove. As a result, it no longer flows out from the second outflow port.

In particular, when the flow rate of one pump connected to the first inlet port exceeds the control flow rate, the check valve closes reliably, completely separating the two pumps.

If both pumps are completely separated, the surplus flow rate of the one pump will not flow out from the second outflow port, and energy loss can be eliminated accordingly.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional device, and FIG. 2 is a sectional view showing an embodiment of this invention. 1... Valve body, 2, 3... 1st, 2nd inflow port, 4... Tank port, 5, 6... 1st, 2nd
Outflow port, P ₁ , P ₂ ... pump, 7 ... tank,
10... Spool, 11-13... First to third annular grooves, 14... Oil passage hole, 15... Control orifice,
20...Check valve, 26...Pressure receiving chamber.

Claims (1)

[Scope of utility model registration request] A first inflow port that communicates with one of the two pumps, a second inflow port that communicates with the other pump, a first outflow port that communicates with a power steering circuit, etc., and a second outflow port that communicates with a work equipment circuit, etc. A spool is slidably provided on a valve body having a tank port communicating with the tank, and first to third annular grooves are formed in the spool, and a spool is provided along the axis of the spool through the first annular groove. The formed oil passage hole is always communicated with the first inflow port, and the oil passage hole is connected to the first inflow port through a control orifice.
While opening to the outflow port side, when the spool is in its original position, the second annular groove communicating with the second outflow port intersects with the second inflow port, and the third annular groove communicating with the oil passage hole opens to the second inflow port. During the movement of the spool, the second inflow port communicates with both the second and third annular grooves, and then the second inflow port passes through the third annular groove and communicates only with the second annular groove. In the related hydraulic distribution device, a check valve is provided in the oil passage hole to open and close a flow path between the oil passage hole and the third annular groove, and the check valve is constantly communicated with the third annular groove around the check valve. Forming a pressure receiving chamber,
A hydraulic distribution device configured to close a communication path between the oil passage hole and the third annular groove when the pressure inside the pressure receiving chamber is equal to or lower than the pressure inside the oil passage hole.