JPH043170Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a relief valve with a so-called anti-void function that replenishes hydraulic oil from the tank port side when the high pressure port side becomes negative pressure.

(Prior Art) In the conventional relief valve shown in FIG. 2, a sleeve 2 is screwed onto a valve body 1, and the outer end of the sleeve 2 is closed with a support member 3.

A first poppet 4 is slidably fitted to the tip of the support member 3, and a seal member 5 is attached to this sliding portion. The first poppet 4 forms a gap 6 with the sleeve 2, and is normally connected to the high pressure port 8 by the action of a spring 7 interposed between the first poppet 4 and the support member 3.
It is in pressure contact with the seat portion 9 of. Furthermore, this first
The diameter of the poppet 4 at the sealing member 5 is made sufficiently larger than the seat diameter of the seat portion 9.

A second poppet 10 is slidably installed inside the first poppet 4 as described above, and a sealing member 11 is also attached to the sliding portion of the poppet 4, so that a seal member 11 is installed between the second poppet 10 and the support member 3. Pilot room 1
It is divided into 2. Furthermore, this second poppet 1
0, a pilot piston 13 is slidably inserted therethrough. This pilot piston 13 is formed with a pilot passage 14 passing through it along its axis, and an orifice 15 is formed at the tip of this pilot passage 14, and a flange 16 is formed at the rear end side.

A spring 17 is interposed between the flange 16 and the support member 3, and under normal conditions, the spring force of the spring 17 keeps the pilot, piston 13, and second poppet 10 in the positions shown. That is, the second poppet 10 is in pressure contact with the seat portion 18 formed in the first poppet 4, and the tip of the pilot piston 13 penetrates the through hole 19 of the first poppet 4 and projects toward the high pressure port 8 side. It is.

Further, a pilot poppet 20 is installed inside the support member 3, and a spring 22 is provided in a drain chamber 21 formed in the support member 3, and the spring force of the spring 22 allows the pilot poppet 20 to move into the seat portion 23. I'm trying to close it.
The pilot poppet 20 thus constructed is provided with a rod portion 24 which projects from the seat portion 23 toward the pilot chamber 12 side. The axes of this rod portion 24 and the pilot piston 13 are aligned so that when the pilot piston 13 moves against the spring 17 and comes into contact with the rod portion 24, the pilot passage 14 is closed. There is.

Thus, the pressure on the high pressure port 8 side is transmitted from the parrot passage 14 to the pilot chamber 12 and acts on the pilot poppet 20. When this acting force overcomes the spring force of the spring 22, the pilot poppet 20 opens and the pilot chamber is communicated with the drain chamber 21. Therefore, the pressure oil in the high pressure port 8 flows through the orifice 15 → pilot passage 14 → pilot chamber 12 → drain chamber 21.
→ Communication hole 25 → Flows to tank port 26 via gap 6.

When a flow is generated in the orifice 15 as described above, a pressure difference is generated before and after the flow, and this pressure difference causes the pilot piston 13 to move until it comes into contact with the rod portion 24. When the pilot piston 13 comes into contact with the rod portion 24, the pilot passage 14 is closed, so that the flow through this passage is interrupted.

Therefore, the pressure oil on the high pressure port 8 side is transferred to the tank port 26 through the clearance formed in the sliding part between the pilot piston 13 and the second poppet 10.
flows to the side.

Therefore, at the intended stage when the pilot poppet 20 is opened, the pressure oil in the high pressure port 8 flows to the tank port 26 via the pilot passage 14.
After the pilot piston 13 contacts the rod portion 24, the pressure oil in the high pressure port 8 flows to the tank port 26 via the clearance.

On the other hand, the pressure on the high pressure port 8 side is
6 side, the first poppet 4 moves against the spring 7 and opens the seat part 9. In other words, in the first poppet 4, the diameter of the portion sealed by the sealing member 5 is made sufficiently larger than the diameter of the seat portion 9, so that the first poppet 4 is 1 poppet 4 opens. When the first poppet 4 opens in this way, the hydraulic oil on the tank port 26 side flows to the high pressure port 8.
Cavitation is prevented since the liquid is fed to the side. In other words, this conventional relief valve also has an anti-void function to prevent cavitation on the high pressure port side.

(Problems to be Solved by the Present Invention) In the case of the conventional relief valve as described above, the pilot poppet 20 is simply brought into pressure contact with the seat portion 23 by the action of the spring 22. When the load was small, there was a problem in that some leakage occurred before the pressure on the high pressure port side reached the set pressure.

Furthermore, in order to provide an anti-void function in addition to the relief function, the second poppet 10 must be installed inside the first poppet 4, which makes the structure complicated.

Furthermore, a seal member 5 must be provided to prevent leakage from the sliding portion of the first poppet 4. Therefore, there was a problem in that the anti-void performance deteriorated due to the influence of friction of the sealing member.

The purpose of this invention is to reduce the amount of initial leakage.
Moreover, it is an object of the present invention to provide a relief valve that is simple in structure and has excellent anti-void performance.

(Means for solving the problem) In order to achieve the above object, this invention forms a high pressure port, a tank port, and a valve hole in the valve body, and forms a communication hole penetrating in the axial direction in the valve hole. The main poppet and the sub-poppet that opens and closes this circulation hole are arranged in series, and the ends of both poppets are butted against each other by the spring force of the spring, and the circulation hole of the main poppet is blocked with the sub-poppet, and a While the above-mentioned high-pressure port pressure acts on the sub-poppet, an introduction hole is formed at the back of the sub-poppet to introduce the pressure from the high-pressure port side to the pressure chamber, and an introduction hole is formed at the outer end on the pressure chamber side. A stopper portion is formed so that when the subpoppet moves by a predetermined amount, the stopper portion prevents the subpoppet from moving.

(Operation of the present invention) Since the present invention is constructed as described above, in the initial stage, the main poppet and sub-poppet move as one due to the pressure action of the pressure chamber, and the spring acting on the main poppet moves as a unit. to deflect. When both poppets move by a predetermined amount, the stopper portion prevents the sub-poppet from moving.

After this movement of the sub poppet is prevented, only the main poppet moves due to the pressure on the high pressure port side. That is, after the sub-poppet stops, both poppets separate, and the flow hole formed in the main poppet opens. Therefore, the pressure fluid on the high pressure port side flows out to the tank port side via this communication hole.

Further, when the pressure on the high pressure port side becomes lower than the pressure on the tank port side, the tank pressure is transmitted through the communication hole and acts on the sub poppet. At this time, the pressure in the pressure chamber acting on the sub poppet is the pressure on the high pressure port side, so due to the effect of the tank pressure,
The sub poppet moves away from the main poppet.

If the subpoppet is separated from the main poppet,
Fluid in the tank flows to the high pressure port side via the main poppet's communication hole.

(Effects of the present invention) According to the relief valve of this invention, at the initial stage when the relief function is exerted, the main poppet and the sub-poppet move together and do not open immediately, so that the main poppet is not immediately opened. Even if the initial load of the spring is somewhat small, the amount of leakage is almost eliminated.

Further, since it is not necessary to provide a sealing member on both poppets, there is no problem that the friction of the sealing member is affected when the anti-void function is performed.

Furthermore, since it is only necessary to arrange the main poppet and the sub-poppet in series, there is an advantage that the structure is extremely simple.

(Embodiment of the present invention) The embodiment shown in FIG.
A high pressure port 28 and a tank port 29 are formed in the valve body 7, and a valve hole 30 is formed in the axial direction of the valve body 27.

The valve hole 30 has a main poppet 31 and a sub-poppet 32 arranged in series, with the outer end of the main poppet 31 facing the relay chamber 33 and the outer end of the sub-poppet 32 facing the pressure chamber into which the tank port 29 opens. I am making it to the 34th.

In addition, the reference numeral 35 in the figure is a cover that blocks the relay chamber 33, and the reference numeral 36 is a plug that blocks the pressure chamber 34.

The main poppet 31 configured as described above has a communication hole 37 formed in its axial direction, and a seat portion 38 at the inner end facing the sub poppet 32.
is formed. And this main poppet 3
1, a flange 39 is formed on the side facing the relay chamber 33, and a spring 40 is interposed between the flange 39 and the cover 35.
Therefore, the main poppet 31 is normally held in its normal position, as shown, in which the flange 39 is brought into contact with the step 41 of the relay chamber 33 under the action of the spring force of the spring 40.

Further, the sub-poppet 32 is brought into pressure contact with the seat portion 38 of the main poppet 31 which is maintained at the normal position as described above by applying the spring force of the spring 42 interposed between the sub-poppet 32 and the plug 36, and the sub-poppet itself is also returned to the normal position. keep it. and,
A flange-like stopper part 43 is formed at the outer end of the sub-poppet 32, but when both poppets 31 and 32 maintain their normal positions as described above, there is a gap between the stopper part 43 and the step part 44 of the pressure chamber 34. , a slight gap l is maintained.

An introduction hole 45 is formed in the sub-poppet 32 as described above, and this introduction hole 45 opens into an annular groove 46 formed on the inner periphery of the valve hole 30. This annular groove 46 is always in communication with the high pressure port 28 , and therefore the pressure chamber 34 is communicated with the high pressure port 28 via this introduction hole 45 .

In addition, main poppet 31 and sub poppet 32
The abutting portion between the two poppets 31 and 32 is also located in the annular groove 46, so that the pressure of the high pressure port 28 also acts on the abutting surfaces of both poppets 31 and 32.

Therefore, the pressure of the high pressure port 28 is
5 into the pressure chamber 34 and acts on the outer end of the sub-poppet 32. At this time, if the pressure in the high pressure port 28 is below the set pressure determined by the spring 40,
Both poppets 31 and 32 maintain their normal positions as shown in the figure, with their tips abutted against each other.

Then, when the pressure of the high pressure port 28, that is, the pressure of the pressure chamber 34, exceeds a certain pressure, the subpoppet 32 is pushed and moves together with the main poppet 31, but when the stopper portion 43 comes into contact with the step portion 44, the subpoppet 32 stops. While the poppets 31 and 32 are moving together in this manner, the seat portion 38 remains seated, so that the amount of leakage is almost eliminated.

After the subpoppet 32 has stopped in this way,
When the pressure in the high pressure port 28 increases and the force acting on the main poppet 31 overcomes the spring force of the spring 40, the main poppet 31 moves against the spring 40. This main poppet 31
As the poppets 31 and 32 move apart and the seat portion 38 opens, the pressurized fluid in the high pressure port 28 is returned to the tank via the communication hole 37→relay chamber 33→tank port 29.

Further, when the pressure on the high pressure port 28 side becomes lower than the pressure on the tank port 29 side, the tank pressure in the flow hole 37 acts on the sub poppet 32, so this sub poppet 32 moves against the spring 42, and the seat part 38 open. In this way, the seat part 3
8 is opened, fluid from the tank port 29 flows to the high pressure port 28, preventing cavitation on the high pressure port 28 side.

The sub-poppet 32, which opens when the anti-void function is performed as described above, does not need to be provided with a sealing member. Things will disappear.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing an embodiment of this invention;
FIG. 2 is a sectional view of a conventional relief valve. 27... Valve body, 28... High pressure port,
29... Tank port, 30... Valve hole, 31...
Main poppet, 32...Sub poppet, 33...
... Relay room, 34 ... Pressure chamber, 37 ... Distribution hole, 4
0,42...Spring, 43...Stopper part,
45...Introduction hole.

Claims (1)

[Scope of utility model registration request] A high pressure port, a tank port, and a valve hole are formed in the valve body, and in this valve hole, a main poppet having a circulation hole penetrating in the axial direction and a sub poppet for opening and closing this circulation hole are arranged in series, and both poppets are connected to each other. The sub-poppet abuts against each other to block the flow hole of the main poppet using the spring force of the spring, and the pressure of the high-pressure port acts on this abutting part. an introduction hole leading to the pressure chamber, and a stopper part is formed at the outer end on the pressure chamber side, and when the sub-poppet moves a predetermined amount, the stopper part prevents the sub-poppet from moving. A relief valve configured to