JPH0379593B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a relief pressure control valve with a pilot poppet.

(Prior technology) As a relief valve with a pressure control function to prevent the pressure in a hydraulic circuit from exceeding a set value, there are two types: a type that operates based on a direct balance between circuit pressure and a set spring load, and a pilot valve. It is broadly divided into types that respond to pressure differences amplified by

The latter allows delicate adjustment of the set pressure and provides a high degree of pressure control accuracy, which will now be explained based on FIG. 1.

In the figure, 1 is a pressure supply port that communicates with a cylinder port, etc., and 2 is a relief port.In order to open and close communication between both ports, there is a relief port inside a check (valve) poppet 3 housed in a valve housing 5. (Valve) A poppet 4 is housed in a freely slidable manner.

The relief poppet 4 opens and closes communication between the through holes 6 and 6b of the check poppet 3, thereby opening and closing the relief port 2.

A cylindrical piston poppet 7 is disposed to freely slide through the relief poppet 4, and the piston poppet 7 is pressed by a relief spring 8 so that the flange portion 9 comes into contact with the inner surface of the relief poppet 4. be done.

The tip of the valve body 10, which is screwed to the housing 5, is inserted into the check poppet 3 so as to be able to slide freely relative to the check poppet 3.
A back pressure chamber 11 is partitioned.

Therefore, pressure oil from the throttled supply port 1 is introduced into the back pressure chamber 11 through the through hole 7a of the piston poppet 7. As will be described later, when the through hole 7a of the piston poppet 7 is closed by the pilot poppet 13, hydraulic pressure is guided through the annular gap 7b on the circumferential surface of the piston poppet 7.

The pilot poppet 13 is urged by the pilot spring 14 and is in pressure contact with the valve seat portion 13a, but when the pressure in the back pressure chamber 11 exceeds the spring set pressure, it opens and communicates the back pressure chamber 11 to the relief port 2. The pressure is reduced by communicating with the passage 17.

Incidentally, the set pressure of the pilot spring 14 can be freely adjusted by an adjusting screw 16.

With the above structure, the relief poppet 4 opens when the pressure in the supply port 1 reaches a set value, but first, the pressure introduced into the back pressure chamber 11 via the piston poppet 7 is When the pressure exceeds the set pressure of the pilot poppet 13, the pilot poppet 13 opens to reduce the pressure in the back pressure chamber 11. The piston poppet 7 moves against the relief spring 8 due to the differential pressure between the pressure in the supply port 1 and the pressure in the back pressure chamber 11, and the piston poppet 13 moves against the relief spring 8.
When it comes into contact with the tip 13b of the through hole 7a, the through hole 7a is closed.

This allows pressure to be supplied to the back pressure chamber 11 between the annular and
7b, the pressure drops further significantly, and the relief poppet 4 opens due to the pressure difference between this reduced pressure and the supply port pressure, so supply port 1 and relief port 2 communicate with each other, discharging some of the pressure oil. It provides relief and maintains the pressure in the supply port 1 at the set pressure.

By the way, this pressure control valve has a suction (anti-void) function in addition to the above-mentioned relief function.

This will be explained in FIG. In the figure, F ₀ ... Set load D ₀ of the relief spring 8 ... Diameter A ₀ of the seat section 18 ... Cross-sectional area D ₁ of the seat section 18 ... Diameter of the large diameter part of the back pressure chamber 11 A ₁ ... Back pressure Cross-sectional area P of the large diameter portion of the chamber 11...Pressure P of the pressure supply port 1...Pressure D of the relief port 2...Bore diameter A of the through hole 7a of the piston poppet 7...Through hole 7a of the piston poppet 7 If the cross-sectional area is , at least when the supply port pressure P is higher than the relief port pressure P, P-P<0, and the relationship P-P<F ₀ /(A ₁ -A ₀ ) is established. However, the check poppet 3 is pressed against the seat portion 18 and closed, as shown by the chain line.

On the other hand, when cavitation occurs on the supply port 1 side and the pressure decreases, P-P>0 and the relationship of P-P>F ₀ /(A ₁ -A ₀ ) is established, and the check poppet 4 As shown by the solid line from 18, the seat part 18 is opened by moving by the amount of movement x.

This allows supply port 1 and relief port 2 to
This allows sufficient oil to be sucked from the relief port 2 side to the supply port 1 side as shown by the arrow to fill the space.

(Problem to be Solved by the Invention) By the way, in order for the check poppet 3 to move by the amount of movement x, the oil in the back pressure chamber 11 must be (A ₁ −A) x
This volume must flow out to the supply port 1 side through the through hole 7a of the piston poppet 7.

At this time, if the diameter D of the through hole 7a is small, the oil will be resisted by the orifice effect, so that the check poppet 3 will be opened slowly. That is, due to the damping resistance related to the check poppet 3, the quick response at the start of suction becomes poor.
This encourages cavitation of the supply port 1.

For the same reason, the return speed response of the check poppet 3 at the end of suction is also as shown by the dotted line in FIG.
Deteriorate.

In particular, the pressure P on the supply port 1 side during suction operation
When the piston poppet 7 rises, the piston poppet 7 contacts the tip of the pilot poppet 13 and is closed, so that oil flows into the back pressure chamber 11 through the annular space 7b between the piston poppet 7 and the relief poppet 4. is supplied.

Therefore, the return of the check poppet 3 is delayed, and as a result, the check poppet 3 and the seat part 1
8, oil flows in the opposite direction to the arrow, and the rise in pressure P is delayed.

In order to eliminate the above-mentioned drawbacks, by increasing the hole diameter D of the piston poppet 7, the differential pressure between the back pressure chamber 11 and the supply port 1 during the relief action becomes smaller.
The quick response of the relief poppet 4 deteriorates. Therefore, as shown in FIG.
Significant fluctuations can be seen in the control of the set pressure before and after the valve starts to open, and the pressure waveform exhibits the characteristic that once it exceeds the set pressure and forms a peak pressure, it drops significantly again to below the set pressure.

In this way, the same pressure in the back pressure chamber 11 is used during relief and anti-void to control the relief poppet 4 during relief and the check poppet 3 during anti-void, so the relief performance and anti-void performance are mutually controlled. There is a problem in that if they are intertwined and the performance of one is improved, the performance of the other becomes worse.

The present invention is intended to solve the above-mentioned problems, and aims to provide a combination type pressure control valve that improves quick response during anti-void and prevents relief performance and anti-void performance from interfering with each other. purpose.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, a relief poppet and an anti-void poppet, which open and close a communication portion between a pressure supply port and a relief port, are provided in the inner hole and the outer periphery of the valve body, respectively. The relief poppet responds to the differential pressure between the back pressure chamber and the supply port, and pressurized oil is introduced into the back pressure chamber through an orifice provided in the relief poppet to reduce this back pressure. The pilot poppet is configured to open when the pressure in the chamber is above a set value to reduce the pressure in the back pressure chamber and open the relief poppet, while the anti-void poppet responds to the differential pressure between the relief port and the supply port. In a pressure control valve configured to open an anti-void poppet when the pressure of a supply port is below a setting, the relief poppet is urged by a relief spring to press against the seat portion of the valve body, while the anti-void poppet is pressed against the seat of the valve body. The poppet is inserted into the outer periphery of the valve body, and an anti-void spring urges the poppet to come into pressure contact with the seat of the pressure supply port. Measures have been taken to avoid interference with the

(Function) Therefore, during relief, the relief poppet is controlled by the pressure in the back pressure chamber, and during anti-void, the anti-void poppet is controlled by the low pressure acting on the anti-void poppet. No pressure is involved, allowing independent and stable control. Furthermore, since the hydraulic oil that flows out during relief does not interfere with the anti-void poppet, the relief characteristics are stabilized.

(Example) Examples will be described below with reference to the drawings. Note that the same reference numerals are used for substantially the same parts as in FIG. 1.

As shown in FIGS. 5a and 5b, the anti-void poppet 20 housed in the valve housing 5 is connected to the valve body 10 which is screwed into the inner hole of the valve housing 5.
The anti-void spring 21 is slidably supported on the outer periphery of the cylindrical portion 10a of the valve body 10, and is pressed so that the other end portion comes into contact with the seat portion 18 by an anti-void spring 21 interposed between one end portion and the valve body 10. Ru.

Further, a relief poppet 4 is slidably housed inside the cylindrical portion 10a of the valve body 10.

The relief poppet 4 opens and closes communication between the through holes 10b and 10c of the valve body 10, and opens and closes the relief port 2 through the passage 22 communicating with the through hole 20a of the anti-void poppet 20 and the relief port 2.

As a means to avoid interference of the oil flow with the anti-void poppet 20 during relief, a sliding key 26 is interposed between the anti-void poppet 20 and the valve body 10, and the anti-void poppet 20 is rotated. In this state, as shown in FIG. 6a, the through hole 10c and the through hole 2 are
It is set so that 0a is always in the middle (at the same position).

The relief poppet 4 is provided with an orifice 23, and the end cone surface 4a is connected to the seat portion 10d of the valve body 10 by the relief spring 8.
is pressed so that it comes into contact with the

A plug 24 is provided inside the valve body 10.
is fixedly installed, thereby defining a back pressure chamber 11 on the side of the relief poppet 4 and a pilot chamber 25 on the side of the pilot poppet 13, which will be described later. Therefore, pressure oil from the throttled supply port 1 is introduced into the back pressure chamber 11 via the orifice 23 of the relief poppet 4.

In the pilot compartment 25, there is a pilot poppet 1.
3 is urged by the pilot spring 14 and is in pressure contact with the valve seat portion 13a, but the back pressure chamber 11
opens when the pressure exceeds the spring setting pressure,
The back pressure chamber 11 is communicated with a passage 22 leading to the relief port 2 via the through hole 10e to reduce the pressure.

Now, when the pressure P in the supply port 1 increases and exceeds the set pressure, the pilot poppet 13 is displaced against the elasticity of the pilot spring 14. The pilot poppet 13 is displaced and the valve seat part 1
When moving away from 3a, the pressure in the back pressure chamber 11 decreases.

Since the pressure of the supply port 1 is introduced into the back pressure chamber 11 through the orifice 23, as the pressure in the back pressure chamber 11 decreases, the relief poppet 4 opens against the spring 8 due to the pressure difference. Therefore, a portion of the pressure oil is relieved to the relief port 2 through the through holes 10c, 20a and the through hole 22, and the pressure in the supply port 1 is maintained at the set pressure.

Next, when the pressure on the supply port 1 side becomes low, the diameter of the large diameter part of the anti-void poppet 20 is D ₁ , its cross-sectional area is A ₁ , the diameter of the small diameter part D ₀ , and its cross-sectional area is
When A ₀ and the set load of the anti-void spring 21 are F ₀ , the relationship PP>F ₀ /(A ₁ -A ₀ ) is established, and the anti-void poppet 20 is
It is displaced to the right in the figure against the elasticity of the anti-void spring 21, and the seat portion 18 is opened.

This allows supply port 1 and relief port 2 to
This allows sufficient oil to be sucked from the relief port 2 side to the supply port 1 side to fill the space created by cavitation.

In this way, during relief, the relief poppet 4 is controlled by the pressure in the back pressure chamber 11, while during anti-void, the anti-void poppet 20 is controlled by the pressure P on the low pressure side acting on the anti-void poppet 20. I try to do that.

Therefore, in each case, the spring constant of the pilot spring 14, the spring constant of the relief spring 8, the hole diameter of the orifice 23, the spring constant of the anti-void spring 21, etc.
The diameter D ₁ of the large diameter portion of the anti-void poppet 20 can be determined independently to optimize the performance of each.

By the way, during relief, the positions of the anti-void poppet 20 and the valve body 10 are prevented from changing in the rotational direction by means of a sliding key 26, so that the through holes 10c and 20a always face each other, and the oil The correct relief setting pressure is maintained.

That is, at the time of relief, the through hole 10c of the valve body 10 and the through hole 2 of the anti-void poppet 20
If 0a is in the middle, the oil to be relieved will flow straight and smoothly as shown by the arrow in FIG. 6a.

However, since the anti-void poppet 20 is slidably supported on the valve body 10, if it rotates and the anti-void poppet 20 is slidably supported on the valve body 10, as shown in FIG.
If 0a is not in the middle of the through hole 10c, the relief oil flow collides with the inner hole wall of the anti-void poppet 20 and is bent as shown by the arrow. As a result, pressure is generated in the vicinity, which is transmitted to the back pressure chamber 11, causing a change in the balance with the tension of the relief spring 8.

Furthermore, if the relative positions of the two through holes are indeterminate, the set load of the relief spring 8 cannot be made to correspond to the set load of the relief spring 8, and therefore, the pressure override characteristic of the static characteristic is limited to the range of the width W, as shown in FIG. The disadvantage is that there are variations in the process, resulting in a lack of reliability.

Therefore, according to this embodiment, since the anti-void poppet 20 is prevented from rotating, such a problem does not occur and high reliability is ensured.

8a to 8c show another embodiment of the interference avoidance means for stabilizing the oil flow during relief, and the difference from FIG. 5 is that the large diameter portion 20b of the anti-void poppet 20 is The through hole 20a is shortened and the end face of the large diameter portion 20 and the valve body 10 are shortened.
An anti-void spring 21 is interposed between the two and a wave washer 27 spanning the through hole 10c.

As shown in FIGS. 8b and 8c, this wave washer 27 is formed by waving a narrow metal plate in the circumferential direction.
Since the thickness T of the metal plate only resists the flow of the relief oil, but rather guides the flow, the resistance to the flow is negligible.

Therefore, this embodiment also produces effects similar to those described above.

Furthermore, in the embodiment shown in FIG. 9, an anti-void spring 21 is interposed between the tip of the valve body 10 and the inner hole end surface of the large diameter portion 20b of the anti-void poppet 20 as a similar avoidance means. 2
The length of 0b is shortened and the through hole 20a is omitted.

In this case as well, since the oil is directly guided from the through hole 10c to the passage 22, the flow is not obstructed and stable relief characteristics can be obtained.

(Effects of the Invention) As explained above, according to the present invention, the relief poppet and the anti-void poppet are biased by dedicated relief springs and anti-void springs, respectively. The void poppet and the void poppet can each be controlled independently, and as a result, the quick response during anti-void can be improved and interference between the relief performance and the anti-void performance can be avoided. Furthermore, the flow of oil when the relief poppet is opened is not impaired by the anti-void poppet, and the relief oil always flows smoothly, ensuring stable relief characteristics.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional valve, and Figure 2 is a cross-sectional view of a conventional valve.
3 and 4 are operational characteristics diagrams, and FIG. 5 shows the first embodiment of the present invention, where a is a sectional view and b is a sectional view. A- of a
6a and 6b are side views showing the relative positions of the relief poppet and the anti-void poppet, respectively, FIG. 7 is a diagram of the operating characteristics of the valve, and FIG. 9A is a cross-sectional view, FIG. 9B and C are a side view and a front view of the wave washer shown in FIG. 9A, respectively, and FIG. 9 is a cross-sectional view of a third embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Pressure supply port, 2... Relief port, 4... Relief poppet, 5... Valve housing, 8... Relief spring, 10... Valve body, 10a... Cylindrical part, 10b, 10c
...Throughout hole, 11...Back pressure chamber, 13...Pilot poppet, 14...Pilot spring, 20
...Anti-void poppet, 20a...Through hole, 2
0b...large diameter section, 21...anti-void spring, 22...passage during relief, 23...orifice, 26...sliding key, 27...wave washer.

Claims (1)

[Claims] 1 A relief poppet and an anti-void poppet that open and close the communication portion between the pressure supply port and the relief port are slidably supported in the inner hole and the outer periphery of the valve body, respectively, and the relief poppet connects the back pressure chamber and the supply port. At the same time, pressure oil is introduced into the back pressure chamber through an orifice provided in the relief poppet, and when the pressure in this back pressure chamber exceeds the set value, the pilot poppet is opened and the back pressure is increased. The anti-void poppet is configured to reduce the pressure in the chamber and open the relief poppet, while the anti-void poppet responds to the differential pressure between the relief port and the supply port and opens the anti-void poppet when the pressure at the supply port is below a set value. In the pressure control valve configured as above, the relief poppet is urged by the relief spring to press against the seat portion on the inner circumference of the valve body, while the anti-void poppet is inserted into the outer circumference of the valve body, and the anti-void poppet is urged by the anti-void spring to press against the seat portion on the inner circumference of the valve body. The anti-void poppet is characterized by being provided with a means for urging the anti-void poppet to come into pressure contact with the seat portion of the pressure supply port, and for avoiding interference between the anti-void poppet and the through hole through which the hydraulic oil flows by passing through the valve body and providing relief. Pressure control valve.