JPH0517684Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pressure reducing valve with a proportional electromagnetic relief.

[Prior Art] A proportional solenoid type pressure reducing valve with relief is designed to control the pressure in a hydraulic system proportionally to the input current by integrally combining a proportional solenoid type pilot relief valve and a pressure reducing valve with relief. Normally, a single spool constituting a pressure reducing valve with relief reduces the pressure of the pressure oil from the primary side and transmits it to the secondary side, and also prevents surge pressure and load pressure fluctuations from the secondary side. The secondary side is configured to open toward the tank port side when abnormal pressure occurs.
However, in such general proportional electromagnetic pressure reducing valves with relief, the open flow path during the relief operation that opens the secondary side to the tank port side must be formed through the spool, so the upper limit of the opening area is This limits the responsiveness especially when the pressure drops, which may cause pressure fluctuations that cannot be ignored depending on the application, or it may take a long time to reach the set pressure, or vice versa. If the aperture area is increased in order to speed up the response, the stability of the original characteristics may deteriorate. That is,
For example, pressure reducing valves used for rolling reduction control in rolling mills, roll bending equipment, etc. are required to have good responsiveness and stability. Pressure reducing valves with relief were considered unsuitable.

Therefore, in the past, a pressure reducing valve with a proportional electromagnetic relief for use in rolling mills and roll bending equipment, for example, has been used in which a pressure reducing valve spool and a relief valve spool are separated, as shown in FIG. The pressure reducing valve with proportional electromagnetic relief shown in Fig. 3 is manufactured by Toyosan Machinery Co., Ltd. (Chiba City, Chiba Prefecture).
Available from.

That is, in FIG. 3, 1 is a pressure reducing valve body, which includes a main spool 5 for the pressure reducing valve and its seat 7.
A relief valve body 2 is disposed at the bottom of the body 1, and a pilot valve 3 is mounted at the top. The relief valve body 2 includes a relief valve body 6 seated on a seat 8 communicating with a passage 14 to the tank by means of a relief valve spring 11, and also includes a relief valve body 6 seated in a seat 8 communicating with a passage 14 to the tank by means of a relief valve spring 11.
includes a pilot poppet 10 which is pressed against the seat 9 via a pilot spring 12 by a proportional electromagnetic solenoid plunger device 4.

Now, the pressure oil flowing in from the primary side pressure port 15 reaches the primary chamber 17 through the passage 16. The main spool 5 is normally pushed downward by a spring 13, and the pressure oil flow passes between the seat 7 and the spool 5 from the secondary chamber 18 to the passage 19.
, passes around the relief valve body 6, reaches the secondary pressure port 20, and is introduced into the actuator. The above is the main line, and the pilot line 21 is led from the secondary passage 19. This pilot line 21 communicates directly with the lower part of the main spool 5, through a throttle 22, to the spring chamber side of the relief valve body 6, further through throttles 23 and 24 to the pilot valve 3, and further through a throttle 25. The upper spring chamber 26 of the main spool 5 is connected to the upper spring chamber 26 of the main spool 5. When the solenoid plunger device 4 is energized with a set current, the pilot poppet 10 is pressed against the pilot seat 9 with the desired force. At this time, the pilot pressure led from the secondary side passage 19 to the pilot line 21 is applied to the upper and lower ends of the main spool and the head side of the relief valve body 6, and reaches the seat 9 of the pilot valve 3 via the passage 27. This pilot pressure pushes poppet 10 up through passage 28 to drain port 29. Now, if the secondary pressure port 20 side is a dead end, the primary pressure will try to flow to the secondary pressure port 20 through the opening in the seat 7 of the main spool 5, but if the pressure exceeds the pressure set by the pilot valve. is poppet 1
Drain port 29 from passage 28 to overcome the force of 0
This prevents the pressure from rising above the set pressure. On the other hand, since the main spool 5 has a pressure difference between the pilot flow at its upper and lower ends due to the orifices 22 to 25, the higher the pilot flow, the lower the pressure at the upper part of the main spool 5 is compared to the lower pressure. 5 is pushed upwards and the main line is narrowed, resulting in
This suppresses the rise in pressure on the secondary side and at the same time prevents pressure changes on the secondary side from being transmitted to the primary side. When the load pressure on the secondary side pressure port 20 decreases, the pilot pressure decreases and the pilot poppet 1
0 is closed, and therefore there is no flow in the pilot line, there is no pressure difference between the top and bottom of the main spool 5, and the force of the spring 13 causes the main spool 5 to descend, widening the opening of the main line and increasing the amount of fluid. The pressure is attempted to be brought close to a predetermined pressure by flowing to the secondary side pressure port 20 side.

In the conventional example shown in FIG. 3, the pressure reducing valve controls the pressure on the secondary side without causing pressure fluctuations on the primary side as described above, and the relief valve directs surge pressure from the secondary side to the tank port 14. Its role is to escape. In other words, the head side of the relief valve body 6 is biased by the pilot pressure and the spring force of the spring 11, and the relief valve body is pressed against the seat 8 with a force that is 10 to 20% higher than the constantly controlled outlet pressure. It functions to prevent a sudden pressure rise by releasing surge pressure to the tank line 14 only when sudden pressure from the secondary side is applied.

[Problem to be solved by the invention] However, in the pressure reducing valve with a proportional electromagnetic relief shown in Fig. 3, for example, in applications for rolling reduction control such as rolling mills and roll bending equipment, it is difficult to introduce pressure oil into the pilot line in a secondary manner. Because it is carried out from the side passage, abnormal pressure on the secondary side due to load fluctuations, etc. is also transmitted to the relief valve spring chamber, which acts in the direction of pressing the relief valve body 6 against the seat 8, resulting in a delay in relief valve operation. leading to malfunction,
There is a drawback that abnormal pressure on the secondary side cannot be removed. In addition, when lowering the set pressure, the main spool 5 for the pressure reducing valve does not have a relief function, and the pressure drop time in the pressure range between the relief valve set pressure and the pressure reducing valve set pressure is limited to the pressure oil escaping from the pilot valve 3. Since it is determined by the flow rate, the response time is extremely long and the response is poor. Furthermore, since the pilot flow rate changes depending on the inlet pressure and the flow rate passing through the pressure reducing valve, the pressure override characteristics are not good, and furthermore, the operating pressure of the relief valve is 10 to 20% of the setting pressure of the pressure reducing valve.
Since the increase is so high, the relief valve does not operate unless the secondary side pressure reaches this value or higher, which also has the disadvantage that it is extremely difficult to settle the secondary side pressure to the set pressure in a short period of time.

Therefore, the object of the present invention is to eliminate the drawbacks of the conventional proportional electromagnetic pressure reducing valve with relief, and to improve the secondary side for rolling control applications such as rolling mills and roll bending equipment. Even if abnormal pressure occurs due to surge pressure or load fluctuations, it is suppressed to a small level, and is released to the tank line in a short time to prevent sudden pressure increases.It also speeds up response and stabilization when pressure drops. Furthermore, it is an object of the present invention to provide a pressure reducing valve with a proportional electromagnetic relief that improves pressure override characteristics by keeping the pilot flow rate substantially constant even if the primary side pressure and the flow rate passing through the pressure reducing valve change.

[Means for Solving the Problems] In order to achieve the above-mentioned problems, the proportional solenoid pressure reducing valve of the present invention has a pressure reducing valve provided between the primary pressure port _P1 and the secondary pressure port _P2 . , the pressure oil flow from the primary side to the secondary side is throttled so that the secondary side pressure received on one end side is balanced with the sum of the spring force of the main pressure reducing valve spring 108 acting on the other end side and the pilot pressure. a main pressure reducing valve 120 that releases the excess pressure to the tank port T by moving against the main pressure reducing valve spring 108 when a secondary side pressure that exceeds the sum acts on one end side while reducing the pressure; A relief valve spring 1 is attached to the valve seat 126 provided between the side pressure port P ₂ and the tank port T.
The poppet valve body 132 has a poppet valve body 132 seated at 34, and the poppet and the seat opening have an area ratio of substantially 1:1, so that the secondary side pressure received on one end surface of the poppet valve body is applied to the other end surface side. A relief valve 140 that opens the secondary side to the tank line when the sum of the spring force of the relief valve spring 134 and the pilot pressure is exceeded, and the pilot line of the main pressure reducing valve 120 and the pilot line of the relief valve 140. a common pilot passage 141 that communicates with each other, and a pilot flow rate adjustment valve 180 that guides the pressure oil of the primary side pressure port _P1 to the common pilot passage 141 at a substantially constant flow rate regardless of changes in the primary side pressure.
and a proportional electromagnetic pilot control valve 160 that controls the pressure in the common pilot passage 141 in proportion to the excitation current.

[Function] The pressure reducing valve with proportional electromagnetic relief of the present invention has the following features:
A relief valve is installed separately from the main pressure reducing valve, and its pilot pressure oil is introduced from the primary side, so surge pressure and abnormal pressure on the secondary side can be reliably and quickly released to the tank line at a large flow rate. Therefore, the response and stability can be maintained at high speed under any circumstances.Furthermore, since the pilot pressure is introduced from the primary side through the pilot flow rate adjustment valve, the pilot flow rate is equal to the primary side pressure and the main pressure reducing valve. The pressure remains almost constant without being affected by the flow rate, and therefore the override characteristics of the pilot valve and, by extension, the pressure override characteristics of the main pressure reducing valve are improved.

In addition, in the proportional solenoid type pressure reducing valve of the present invention, the main pressure reducing valve also has a relief function. Therefore, when the set pressure of the pressure reducing valve is lowered by, for example, the proportional solenoid type pilot control valve, the pressure will be higher than the pressure reducing valve set pressure. The pressure reduction of the secondary side pressure in the above-mentioned intermediate pressure range up to the relief valve set pressure is also quickly performed by the relief function of the main pressure reducing valve, resulting in faster response and stabilization over the entire operating pressure range of the main pressure reducing valve. It is possible.

In the present invention, the relief valve spring may be a variable adjustment spring whose spring force can be adjusted from the outside, so that the pressure difference between the main pressure reducing valve and the relief valve can be set to a desired value. This pressure difference corresponds to the size of the intermediate pressure range, but in the present invention, the relief valve is composed of a poppet valve body, and the area ratio of the poppet to the seat opening is substantially 1:1.
This pressure difference does not change even when the set pressure is changed by controlling the pilot pressure in the common passage, and the response and stability are always stable within the control range of the pressure reducing valve. Become.

For a better understanding of the present invention, examples thereof are given below.

[Embodiment] Fig. 1 is a schematic sectional view showing a pressure reducing valve with proportional electromagnetic relief according to an embodiment of the present invention, and Fig. 2 is a circuit diagram showing it with hydraulic symbols.

In FIG. 1 and FIG. 2, the whole number is 10.
The proportional electromagnetic pressure reducing valve with relief according to the present invention, indicated by 0, has four main components: a main pressure reducing valve 120, a relief valve 140, a pilot pressure control valve 160, and a pilot flow rate adjustment valve 180.
Consisting of

The primary pressure port P ₁ communicates with chamber A within the valve body 102, and the secondary pressure port P ₂ similarly communicates with chamber B.
is connected to. A chamber C that communicates with the tank port T is provided on the opposite side of the chamber A with the chamber B in between, and a chamber D that is coaxial with the chamber A is provided on the opposite side of the chamber B with the chamber A in between. ing.

A main pressure reducing valve spool 106 is slidable in a valve hole 104 that penetrates from chamber B to chambers A and D to one side of the valve body 102, and is pressed to the left in the figure by a spring 108. Room A
A control hole 110 is provided in the spool 106, which communicates with the spool 106 and B at an initial opening degree. This spool 10
6 also has a partition wall 114 that separates a spring chamber 112 within the valve hole 104 from chamber B. The control hole 1
10, as the spool 106 moves to the right in the figure against the spring 108, the opening degree becomes smaller, gradually cutting off the communication between chambers A and B, and when the spool 106 moves further to the right, it opens to chamber D. chamber B and chamber D are communicated with each other. The chamber D communicates with the tank port T, and in the illustrated example, an adjustable throttle 116 is provided in the middle,
By adjusting the throttle opening degree, the amount of secondary pressure oil released in the above-mentioned intermediate pressure range is regulated to a desired value, thereby making it possible to prevent a pressure drop below a desired set pressure as necessary.

A valve hole 122 that penetrates from chamber B to chamber C to the opposite side of the valve body has a seat hole 124 and a tapered seat surface 126 at its tip, and a hole that opens into chamber C on the inside thereof. Sleeve 1 with 128
30 is inserted and fixed therein, and a relief valve poppet 132, which is seated on the seat surface 126 with its distal end edge, is elastically mounted within this sleeve by a spring 134. The initial deflection of the spring 134, and thus the spring force thereof, can be variably adjusted by means of a pressure adjusting screw 136. The poppet 132 has a wall 139 at its tip that separates the spring chamber 138 from the chamber B.

A common pilot passage 141 is bored through between the left and right sides of the valve body 102, communicating with the spring chamber 112 of the main pressure reducing valve 120 via a throttle 142 and a large volume chamber 143 at one end, and communicating with the spring chamber 112 of the main pressure reducing valve 120 at the other end. It communicates with the spring chamber 138 of the relief valve 140 via the large volume chamber 144 and the throttle 145 . A pilot pressure control valve 1 is installed in the common pilot passage 141.
The seat hole 152 of the sheet 151 of 60 is the aperture 15
3, and this seat hole 152 reaches a drain passage (not shown) via a pilot poppet 154. Pilot Poppet 154
is pressed against the seat 151 via the pilot poppet spring 155 by a solenoid plunger device 156. is pressed onto the sheet 151.

Pilot pressure is introduced into the common pilot passage 141 from chamber A through the pilot flow rate adjustment valve 180.
It is done through. Pilot flow rate adjustment valve 180
The spool 164 has a spool 164 having a diaphragm 162 opening into the chamber A at its tip, and is pressed toward the chamber A side by a spring 166. In this state, a control hole 172 that opens at a predetermined initial opening degree in a chamber 168 in the middle of the common pilot passage 141 is provided in the spool 164. The primary pressure is introduced from The spool 164 receives the primary side pressure of the chamber A on its tip surface,
The opening degree of the control hole 172 is controlled by the balance between this and the spring 166, and the pilot flow rate is controlled to be constant regardless of changes in the primary pressure. Note that this spring 166 may be variably adjustable.

The operation of this embodiment will be described below.

The pressure oil flowing from the primary side pressure port P ₁ is in the chamber A.
to go into. The spool 106 is pressed to the left in the figure by a spring 108, and the pressure oil in the chamber A flows from the control hole 110 of the spool 106, passes through the chamber B, and reaches the secondary pressure port _P2 to maintain the pressure at a predetermined value. It is controlled to reduce the pressure and is introduced into an actuator such as a cylinder.
A pilot line is led from chamber A, and a pilot flow regulating valve 1 is installed in the middle of the pilot line.
80, whose spool 164 moves against a spring 166 so that the differential pressure across the throttle 162 is constant, controls the opening degree of the control hole 172, and flows out to the secondary side chamber 168. Controls the pilot flow rate to a constant value regardless of pressure changes on the primary side. The pressure oil whose flow rate is controlled to be constant in this manner flows into the common pilot passage 141 from the secondary side chamber 168 of this pilot flow rate regulating valve 180, and on the other hand, the pressure oil is controlled to have a constant flow rate.
2 and flows into the pressure reducing valve spring chamber 112 via the large volume chamber 143, and on the other hand flows into the relief valve spring chamber 138 via the large volume chamber 144 and the throttle 145. Furthermore, a pilot pressure control valve 160 is branched and connected to the common pilot passage 141, and pilot pressure oil reaches the pilot seat front chamber 157. The pilot pressure oil in the pilot seat front chamber 157 passes through the throttle 153 and the seat hole 152, pushes up the pilot poppet 154, and returns to the tank from a drain (not shown).

Now, if the pressure oil flow stops (dead end) in the secondary pressure port P ₂ , the pressure oil in the primary pressure port P ₁ will flow through the control hole 110 of the pressure reducing valve spool 106 and the chamber B to the secondary side. When the pressure in chamber _B exceeds the pressure set by the pilot pressure control valve 160, the spool 106 closes the control section consisting of the edge of chamber A and the control hole 110. direction (to the right in the figure), and as a result, the pressure at the secondary pressure port _P2 does not exceed the set pressure. When the secondary pressure falls below the set pressure, the spool 106 moves to the left in the figure due to the spring force of the pilot pressure plus spring 108 acting on the spring chamber 112, and air flows from the primary pressure port _P1. In this case, more pressure oil is allowed to flow into the secondary pressure port _P2 in an attempt to bring the pressure on the secondary side closer to a predetermined pressure.

The main pressure reducing valve 120 controls the secondary side port pressure as described above.

In the figure, a relief valve 140 located to the left of the pressure reducing valve spool 106 serves to release pressure to the tank port when the secondary port pressure exceeds its set pressure. That is, the relief valve poppet 132 is
Due to the pilot pressure acting on the spring chamber 138 plus the spring force of the spring 134, the sleeve 13 is always
0 sheet surface 126. The spring force of the spring 134 is always stronger than the force of the pressure reducing valve spring 108 by a certain value even when the pressure regulating screw 136 is in the fully open position, and the relief valve poppet 132 will not open below the secondary set pressure. do not have.

Only when pressure oil at a pressure higher than the pilot set pressure pressure relief valve setting pressure is applied to the secondary side pressure port _P2 from the outside, the relief valve poppet 132 moves to the left in the figure and releases the pressure oil to the tank port T. Keep the outlet pressure constant. Since the set pressure of the relief valve 140 is always higher than the set pressure of the main pressure reducing valve 120, in the intermediate pressure range between the set pressure of the main pressure reducing valve 120 and the set pressure of the relief valve 140, an abnormality from the secondary side will occur. The pressure is spool 1
06 moves to the right in the figure, and chambers B and D communicate with each other through the control hole 110 of the spool 106, allowing the fluid to escape to the tank port T.
Therefore, the secondary pressure in the intermediate pressure range is also settled in a short time. In this embodiment, a throttle 116 is placed halfway from the chamber D to the tank port T, and by adjusting the opening degree of the throttle 116, the amount of water released into the tank in the intermediate pressure range can be regulated. Therefore, it is possible to prevent the pressure from becoming lower than a predetermined set pressure. Furthermore, if the area ratio between the poppet diameter of the relief valve poppet 132 and the seat diameter of the sleeve 130 is set to 1:1, the pressure difference between the relief valve and the main pressure reducing valve will always be constant even if the set pressure changes. Furthermore, large volume chambers 143, 144
By increasing the volume of the pilot line, it is possible to eliminate small surges that tend to occur when the secondary pressure rises and further shorten the settling time.

[Effects of the invention] As described above, according to the invention, a relief valve is arranged separately from the main pressure reducing valve, and the pilot pressure oil is introduced from the primary side, so that surge pressure and pressure on the secondary side are reduced. Abnormal pressure caused by load fluctuations can be reliably and quickly released to the tank port at a large flow rate, which can speed up response and stabilization, and is effective in removing surge pressure. Since it is introduced via a flow rate adjustment valve, the pilot flow rate is always almost constant without being affected by the inlet pressure or the flow rate passing through the main pressure reducing valve.
The pilot valve has good pressure override characteristics.
Therefore, the override characteristics of the main pressure reducing valve are also excellent. A pressure reducing valve with a proportional electromagnetic relief that is suitable for use when you want to reduce surge pressure, shorten the settling time, or remove abnormal pressure in a circuit where abnormal pressure occurs on the secondary side. is obtained.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention, FIG. 2 is a circuit diagram similarly shown with hydraulic symbols, and FIG. 3 is a longitudinal sectional view showing a conventional example. 100...Pressure reducing valve with proportional solenoid relief, 1
20... Main pressure reducing valve, 140... Relief valve, 16
0...Pilot pressure control valve, 180...Pilot flow rate adjustment valve, 108...Main pressure reducing valve spring, 13
4...Relief valve spring, 141...Common pilot passage, _P1 ...Primary side pressure port, _P2 ...Secondary side pressure port, T...Tank port.

Claims (1)

[Scope of claims for utility model registration] 1. Primary side pressure port P ₁ and secondary side pressure port P ₂
from the primary side to the secondary side so that the secondary pressure received on one end side is balanced with the sum of the spring force of the main pressure reducing valve spring 108 acting on the other end side and the pilot pressure. When the flow of pressure oil is throttled to reduce the pressure and a secondary pressure exceeding the sum acts on the end surface side, the main pressure reducing valve spring 108
The main pressure reducing valve 120 releases the excess pressure to the tank port T by moving against the pressure, and the valve seat 126 provided between the secondary pressure port _P2 and the tank port T is provided with a relief valve spring 134. It has a poppet valve body 132 that is seated, and the poppet and the seat opening have an area ratio of substantially 1:1, and the secondary pressure received on one end surface of the poppet valve body acts on the other end surface. a relief valve 140 that opens the secondary side to the tank line when the sum of the spring force of the relief valve spring 134 and the pilot pressure is exceeded; a pilot line of the main pressure reducing valve 120 and a pilot line of the relief valve 140; a common pilot passage 141 that communicates with each other, a pilot flow rate adjustment valve 180 that guides the pressure oil of the primary side pressure port _P1 to the common pilot passage 141 at a substantially constant flow rate even when the primary side pressure changes; A proportional solenoid type pilot control valve 160 that controls the pressure in the passage 141 in proportion to the excitation current. 2. The pressure reducing valve with a proportional electromagnetic relief according to claim 1 of the registered utility model, characterized in that the relief valve spring 134 is a variable adjustment spring whose spring force can be adjusted.