JPS6229643B2 - - Google Patents

Description

Detailed Description of the Invention (Industrial Application Field) This invention divides hydraulic oil from a pump into two directions, a primary side port and a secondary side port. The present invention relates to a flow control valve that connects a port to a power steering device and a secondary port to a working machine side.

(Prior art) The conventional flow control valve shown in FIG.
An inlet port 22, a primary port 23, and a secondary port 24 are formed on the spool 2.
5 inside so that it can slide freely.

This spool 25 has an annular groove 26 that constantly communicates with the inflow side port 22, and a plug 2 provided at the tip of the spool 25 and the valve body 21 side.
7, a pressure chamber 28 is formed. This pressure chamber 28 communicates with the inlet port 22 via a damping orifice 29 and an annular groove 26 .

When hydraulic oil flows in from the inflow side port 22, this hydraulic oil flows from the annular groove 26 to the spool 2.
The liquid flows out from the primary port 23 via a fixed orifice 30 formed at 5.

Then, the differential pressure before and after the fixed orifice 30 changes depending on the flow rate from the inflow side port 22, and the pressure inside the pressure chamber 28 changes accordingly. Due to the pressure action of the pressure chamber 28, the spool 25 moves against the spring 31, adjusting the opening degree of the control section 32 of the primary port 23, and the annular groove 28
The inflow side port 22 and the secondary side port 24 are communicated via the inflow side port 22 and the secondary side port 24.

Now, if the pump rotational speed is low, below point A in FIG.

Also, if the pump rotation speed exceeds point A in Figure 3,
Since the differential pressure before and after the fixed orifice 30 increases,
As the spool 25 moves to throttle the control section 32, the inlet port 22 also communicates with the secondary port 24 via the annular groove 26, as shown in FIG.

Therefore, when the rotational speed of the pump exceeds the above point A, a constant controlled flow flows out from the primary port and is supplied to the power steering device, and the surplus flow flows from the secondary port to the actuator of the work equipment system. is supplied to

(Problems to be Solved by the Invention) In the conventional control valve as described above, when the pump rotation speed is near point A, the surplus flow rate is zero or very small. However, a certain amount of surplus flow may be required. for example,
When the control valve is used in an agricultural tractor, and the primary port is connected to power steering and the secondary port is connected to the actuator of the work equipment system, when idling (near point A above)
This is the case when the actuator of the work equipment is activated.

In such cases, conventional flow control valves have had problems such as not being able to secure a sufficient surplus flow rate and therefore not being able to operate the actuator of the working machine system.

An object of the present invention is to provide a flow control valve that reduces the controlled flow rate of the primary port in the vicinity of the point A, and allows the decreased amount to flow out from the secondary port as surplus flow.

(Means for Solving the Problems) In order to achieve the above object, the present invention includes an inflow side port that guides the hydraulic oil from the pump into the valve body, and an inflow side port that causes the hydraulic oil to flow out from the inflow side port. It is equipped with a primary side port, a secondary side port, and a spool that slides according to the inflow amount from the inflow side port and causes a constant controlled flow rate to flow out from the primary side port and excess flow rate to flow out from the secondary side port. In the flow control valve, a control rod is inserted into the spool, and the spool is slidable with respect to the control rod. While forming a fixed orifice located at It consists of both a control rod and a spool.

(Operation of the present invention) With the above structure, only the fixed orifice opens when the pump rotation speed is low and the amount of inflow from the inlet side port is small, and when the amount of inflow increases, the variable orifice gradually opens. Open to. When the variable orifice opens in this manner, the hydraulic oil that has flowed into the inlet port flows out to the primary port via both the fixed orifice and the variable orifice.

Therefore, when the flow rate flowing in from the inflow side port is less than the control flow rate, only the fixed orifice opens, so that out of the total pump discharge amount, the flow rate supplied to the primary side port is supplied to the secondary side port. The flow rate will be relatively smaller than the flow rate. In other words, the flow rate flowing out from the secondary port becomes relatively large.

When the flow rate flowing in from the inlet port exceeds the control flow rate, both the fixed orifice and the variable orifice open, allowing the control flow rate to flow out from the primary port and the excess flow rate exceeding the control flow rate to the secondary port. It can be drained from.

(Effects of the Invention) According to the flow control valve of the present invention, even when the pump rotation speed is low and the amount of inflow from the inflow port is small, hydraulic oil can be supplied to the secondary port.
For example, there is an effect that the actuator of the working machine can be operated even when the system is idling.

(Embodiment of the present invention) In the embodiment of the present invention shown in FIGS. 1 and 2, an inlet port 2, a primary port 3, and a secondary port 4 are formed in the valve body 1, and a spool
is slidably installed inside the valve body 1.

The spool 5 is applied with a required force by a spring 6, and normally comes into pressure contact with a plug 7 fitted on one side of the valve body 1.
A pressure chamber 8 is formed between the two.

A control rod 9 is slidably housed in the plug 7, but this control rod is normally kept in the state shown in the figure by a spring 10, and its tip protrudes into the spool 5. It is possible to move relative to.

When the hydraulic oil from the pump flows into the inflow side port 2, the hydraulic oil passes through the annular groove 11 formed in the spool → the oil passage hole 12 → the communication hole 13 formed in the control rod 9 → the fixed orifice 14. It flows out from the primary port 3 and also flows into the pressure chamber 8 via the damping orifice 15.

When the hydraulic oil flows from the inflow side port 2 to the primary side port 3 as described above, a pressure difference is generated before and after the fixed orifice 14.

This pressure difference increases as the amount of inflow from the inlet port increases, in other words, as the pump rotation speed increases, but as this pressure difference increases,
The pressure within the pressure chamber 8 overcomes the reaction force of the spring 6 and moves the spool 5.

However, when the rotation speed of the pump is at point B in FIG. 2, the amount of overlap between the annular groove 11 and the secondary port 4 is set to zero.

In the range where the pump rotation speed exceeds the above point B and reaches point C, the spool 5 moves further, and its annular groove 11 overlaps the secondary port 4, causing the inflow port 2 and the secondary port 4 to be connected. Through this communication, pressure oil is supplied to the secondary port 4.

At this time, the control section 16 of the primary port 3 is throttled, and the pressure in the pressure chamber 8 and the spring load of the spring 6 and the pressure on the spring side are balanced.
The flow rate from the primary port 3 is controlled to be constant.

Furthermore, the rotation speed of the pump increases from point C to D
When the point is reached, the oil passage hole 12 and the variable orifice 17
communicate with. This variable orifice 17 has a tapered portion 1 formed on the outer periphery of the tip of the control rod 9.
8 and a horizontal portion 19 in front of which the cross section is horizontal, and the inner surface of the spool 5 are formed together, and when the rotation speed of the pump exceeds point D, the tapered portion 18 faces the communication hole 12. We have a relationship where we

When the variable orifice 17 gradually opens as described above, this is essentially the same as increasing the opening area of the fixed orifice 14, so the amount of outflow from the primary port increases.

When the rotation speed of the pump exceeds point D, the horizontal portion 19 faces the oil passage hole 12, and the opening degree of the variable orifice 17 becomes constant, so that the flow rate from the primary port 3 is controlled to be constant. becomes the flow rate.

In short, when the pump rotates at low speed, only the fixed orifice 14 is opened to reduce the flow rate from the primary port 3, and the reduced flow rate is allowed to flow out from the secondary port 4. This is to ensure a surplus flow rate Q of the secondary side port 4 near point A.

When the primary port 3 is connected to the power steering and the power steering is operated at point A, the load pressure on the primary port 3 side acts on the tip of the control rod 9, causing it to move against the spring 10. Since the horizontal part 19 is made to face the oil passage hole 12,
A controlled flow rate from the primary port 3 can be ensured.

Therefore, when the controlled flow rate from the primary port 3 is not required, the outflow amount is reduced,
While letting the surplus flow flow out from the secondary side port 4,
When a predetermined control flow rate is required, it can be sufficiently ensured.

[Brief explanation of the drawing]

Drawings 1 and 2 show an embodiment of the present invention, in which Fig. 1 is a sectional view, Fig. 2 is a graph showing the relationship between pump rotation speed and flow rate, and Fig. 3 is a graph showing the relationship between pump rotation speed and flow rate. FIG. 4 is a graph showing the relationship between the pump rotation speed and flow rate of the control valve, and is a sectional view of a conventional control valve. 2...Inflow side port, 3...Primary side port, 4...Secondary side port, 5...Spool, 9...Control rod, 10...
Spring, 11... Annular groove, 12... Oil hole, 14
...Fixed orifice, 17...Variable orifice.

Claims (1)

[Claims] 1. An inflow side port that guides the hydraulic oil from the pump into the valve body, a primary side port and a secondary side port that flow out the hydraulic oil from this inflow side port, and slides according to the inflow amount from the inflow side port. In a flow control valve comprising a spool that allows a constant controlled flow rate to flow out from the primary port and a spool that allows the surplus flow to flow out from the secondary port, a control rod is inserted into the spool, and In addition to making the spool slidable, this control rod has a fixed orifice located in the communication path between the inflow side port and the primary side port. , a flow control valve in which a control rod and a spool constitute a variable orifice that increases the opening area when the spool slides in the direction of decreasing the opening of the primary port.