JPS6338781A - Electropneumatic proportional valve - Google Patents

Abstract

PURPOSE:To enhance the responsiveness of an electropneumatic proportional valve driven by an actuator, by acting the fluid pressure of an output port upon a feed-back chamber formed in a spool in the proportional valve. CONSTITUTION:A valve part 11 in a proportional valve has output ports 17a, 17b and discharge ports 18a, 18b, and a spool 20 changes over the communication of a supply port 16 among the above-mentioned ports. Further, the pressure of the output ports 17a, 17b is applied to feed-back chambers 25, 38. Accordingly, the valve may feed and discharge pressure fluid into and from an actuator and holds the pressure of the fluid at predetermined value. Further, the pressure difference between the outlet ports may be made to constant, thereby it is possible to enhance the responsiveness of the actuator.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an electropneumatic proportional valve for driving an actuator that needs to maintain a constant acting force at the end of its stroke.

[Prior Art] For example, in spot welding, in order to press an energized electrode with a constant force, the actuator that drives the electrode is required to maintain a constant force at the end of the stroke. Ru.

Conventionally, in order to configure a drive circuit for this type of actuator, normally, as shown in FIG.
! A'Ih side pressure chamber 2 side pressure return chamber 2 A 5-port solenoid valve 5 that selectively supplies and discharges high-pressure air from an air source 4 to and from the force chamber 3, one of the output ports of the solenoid valve 5, and the drive side pressure chamber 2 An electropneumatic proportional valve 6 disposed in the flow path between the two is used. The electropneumatic proportional valve 6
outputs a fluid pressure proportional to the amount of current applied to the solenoid.

The fluid pressure cylinder l has a solenoid valve 5 in the illustrated state.
When the electro-pneumatic proportional valve 6 is energized, the flow path of the 5-port solenoid valve 5 is switched, and high-pressure air from the high-pressure air source 4 is supplied to the drive-side pressure chamber 2 through the electro-pneumatic proportional valve 6. The fluid in the return side pressure chamber 3 is discharged, and in this case, the fluid pressure supplied to the drive side pressure chamber 2 is controlled by the fluid pressure proportional to the amount of current supplied to the electropneumatic proportional valve 6. The piston of the cylinder l maintains a predetermined acting force proportional to the amount of current applied to it at the end of the drive stroke.

When the power to the valves 5 and 6 is cut off, they switch to the state shown in the figure, so that the high-pressure air from the air source 4 is supplied to the return side pressure chamber 3, and the fluid in the drive side pressure chamber 2 is discharged, and the fluid The pressure cylinder 1 returns to the state shown.

However, in the above actuator drive circuit, 2
Not only do they require separate solenoids, but because the properties of the two solenoids are different, their energization systems are different, which makes the whole thing relatively expensive. , consideration must be given to prevent the actuator from malfunctioning even if there is a failure in any of the energizing systems during work.

Furthermore, connecting multiple valves in series as described above creates a large resistance to the pressure fluid, which is not desirable, especially when starting and stabilizing the actuators driven by these valves. A delay in the generation of a physical output has a large impact on the efficiency of the work performed by the actuator, so it is desirable to improve this.

[Problems to be Solved by the Invention] The present invention enables an actuator that requires a constant acting force to be maintained at the end of its stroke to be driven by a single, inexpensive valve, and also enables pressure chambers facing each other in the actuator to be driven by a single inexpensive valve. The problem to be solved is to make it possible to set the differential pressure of the pressure fluid between a pair of output ports that communicate with each other to a constant value in terms of responsiveness.

[Means for Solving the Problems] The present invention provides a valve body having a supply port, first and second output ports, and first and second discharge ports, which switches the flow path between each port. In a valve including a valve part provided with a valve member, a drive part that applies a driving force to one end of the valve member, and a return spring that applies a return force to the other end of the valve member, the valve part is placed in a neutral state. By displacing the valve member across the position, one of the supply port and the output port and the other of the discharge port and the output port are brought into communication, respectively, and the supply port is closed and the first or second output port is connected to the discharge port. Configured as a 5-port valve that allows communication in a throttled state,
First and second feedback chambers that act on the valve body to apply feedback fluid pressure in the drive and return directions to the valve member, and first and second feedback chambers that communicate the feedback chambers with each output port. The above-mentioned problem is solved by providing a passage and constructing the driving section by a driving force generating means that outputs a driving force to the valve member that is proportional to the amount of current applied to the proportional solenoid.

[Operation] When the proportional solenoid is de-energized, the spool is displaced by the biasing force of the return spring, and the flow path between the supply port and the second output port and the flow path between the first output port and the first discharge port are closed. It's communicating. Accordingly, the first feedback chamber communicates with the first exhaust port, and the second feedback chamber is supplied with pressure fluid through the second feedback passage.

In this state, when the proportional solenoid is energized, a driving force proportional to the amount of energization from the drive unit to the solenoid is output, and the spool is displaced against the biasing force of the return spring, causing a gap between the supply port and the first output port. Since the flow path between the second output port and the second discharge port communicate with each other, the feedback fluid pressure in the second feedback chamber decreases and the feedback fluid pressure in the first feedback chamber increases.

As a result, when the fluid pressure in the first feedback chamber becomes larger than the set value, the spool is displaced in the opposite direction, the fluid pressure in the first feedback chamber decreases, and the fluid pressure in the second feed bar chamber increases. .

When the amount of energization of the proportional solenoid is equal to or higher than a certain value determined by the biasing force of the return spring, due to the displacement of the spool described above, the spool receives a driving force proportional to the amount of energization of the proportional solenoid, the biasing force of the return spring, and the first The force exerted by the fluid pressure in the feedback chamber is balanced, the supply port and the first output port are cut off, the second output port and the second exhaust port are maintained in a throttled state, and the first output port is kept in communication with each other. The output pressure is set to a predetermined pressure determined by the amount of current applied to the proportional solenoid.

In this case, the spool is displaced by the difference in fluid pressure between the first and second feedback chambers acting on both ends, in other words, the difference in fluid pressure between the first and second output ports. Since the fluid pressure in the port becomes constant before reaching the final set point, the pressure applied to the actuator becomes constant in a very responsive manner.

[Embodiment] FIGS. 1 to 6 show a first embodiment of the present invention, and this electropneumatic proportional valve is composed of a valve section 11, a driving section 12, and a base 13.

The valve body 15 in the valve section 11 has first and second output ports 17a connected to the pressure fluid supply port 16.
, 17b, and the first and second exhaust ports 18a
, 18b, and the valve body 15 is provided with a sleeve 19 having openings communicating with each of the ports, and within the sleeve 19 are a supply port 16 and an output port 17a.

A center switching spool 20 is slidably inserted to switch the flow path between the output ports 17a and 17b and the flow path between the output ports 17a and 17b and the discharge ports 18a and 18b.

The spool 20 has a flow path between the supply port 16 and the second output port 17b and a flow path between the first output port 17a and the first discharge port 18a, and a second discharge port 18b.
From the closed state, the flow path between the supply port 16 and the first output port 17a and the flow path between the second output port 17b and the second discharge port 18b are communicated, and the first discharge port 18a is opened.
A first intermediate state in which the supply port (1B) is closed and only the flow path between the first output port (17a) and the first discharge port (18a) is in communication in a constricted state while the supply port (1B) is displaced to a closed state; The supply port 16 is closed and only the flow path between the second output port 17b and the second discharge port 18b communicates in a throttled state.
(See Figure 2).

A stopper 21 and a spring seat 22 are fitted into both ends of the sleeve 19 inside the valve body 15, and the spring seat side end of the valve body 15 is closed by a cover 23. Stopper 21
has a through hole 24 in the axial direction, a first feedback chamber 25 is formed between the spring seat 22 and the spool 20, the spool 20 is contracted in the first feedback chamber 25, and a return spring 26 is formed. A shaft rod 27 that is pressed against the stopper 21 by the urging force of the spool and protrudes from the end face of the spool extends into the through hole 24 .

On the other hand, the drive unit 12 connects the rod 29, one end of which is in contact with the shaft rod 27, to the movable core 32, which is attracted to the fixed core 31 by energizing the coil. It is configured as a proportional solenoid 30 in which the attraction force between 31 and 32 is approximately proportional to the amount of current applied to the coil.

The base 13 has a supply port P and a WA of the actuator 1.
It has two output ports A and B and two discharge ports E a and E b that communicate with the moving chamber 23 , and passages (not shown) that communicate with each of these openings separately. When the valve part 11 is placed and fixed on top, each bow in the valve part 11) 16, 17a, 1? b.

18a and 18b, respectively. Further, the passage communicating with the output port A is communicated with the first feedback chamber 25 through the first feedback passage 36 opened in the valve body 15, and the passage communicating with the output port B is connected with the first feedback chamber 25 through the first feedback passage 36 opened in the valve body 15. aisle 37
By this, the second
It communicates with a feedback room 38.

In FIG. 1, reference numeral 39 is a socket for feeding power to the coil.

Next, the operation of the first embodiment will be explained with reference to FIGS. 1 to 6.

FIG. 1 shows a state in which the proportional solenoid 30 is de-energized, the spool 20 is displaced by the urging force fk of the return spring 26, the second discharge port 18b is closed, and the gap between the supply bow 16 and the second output port 17b is flow path, and first output capo) 1
7a and the first discharge port IBa communicate with each other, and the second feedback chamber 38 has a flow path between the second output port 17b and the second
Pressure fluid is supplied through a feedback passage 37, while the first feedback chamber 25 communicates with the first discharge port 18a by a first feedback passage 36.

In this state, when the coil of the proportional solenoid 30 is energized with an amount of current greater than a certain value, an attractive force F proportional to the amount of current applied to the coil is generated between the fixed core 31 and the movable core 32, and this attractive force F is transient. When the sum of the acting force fb of the fluid pressure in the second feedback chamber 38 becomes larger than the biasing force fk of the return spring 26, the spool 20 is displaced by this force. In this case, the acting force rb due to the fluid pressure in the second feedback chamber 3 days after the energization of the solenoid 30 acts on the spool 20, and since the first feedback chamber 25 is open to the outside, the spool 20 is quickly turned off. Displaced to.

When the amount of energization to the coil is larger than the constant energization tic determined by the biasing force fk of the return spring 26, the displacement of the spool 20 causes it to close the first discharge port 18a and connect the output port 16 and the first It is transiently displaced to a position where the flow path between the output ports 17a and the flow path between the second output port 17b and the second discharge port 18b are brought into communication (see FIG. 3).

As a result, the pressure fluid from the first output port 17a is supplied to the first feedback chamber 25, the acting force fa due to the fluid pressure in the first feedback chamber 25 increases, and the fluid in the second output port 17b is supplied to the second output port 17a. discharge bow)
18b, the acting force fb due to the fluid pressure in the second feedback chamber 38 decreases, and the spool 20 is accordingly displaced (see Fig. 4), and finally the first output is in the state shown in Fig. 5. A set pressure is obtained at port 17a.

As mentioned above, the spool 20 has a fluid pressure acting force fa in the feedback chamber 25.38 acting on both ends of the spool 20.
The displacement is caused by the difference in fb, in other words, the differential pressure between the fluid pressures at the first output port 18a and the second output auto 18b, and this differential pressure is determined by the fluid pressure at the first output port 17a and the amount of current applied to the coil. Since the pressure becomes almost constant before being held at a constant pressure, the output of the actuator driven by this will already reach a constant set value during the actuator's stroke, providing excellent responsiveness. .

When the flow 11tffi to the solenoid 30 is less than the above IC, the spool 20 is activated so that the sum of the suction force F and the acting force fb of the second feedback chamber 38 is equal to the biasing force fk of the return spring 26.
Since the pressure of the second output capacitor 17a is maintained at the fluid pressure pb which is proportional to the amount of current supplied to the solenoid 30 (see FIG. 6).

FIG. 7 shows an experimental example of the relationship between the percentage of the energization amount to the proportional solenoid 30 and the fluid pressure at the output ports A and H. In this experimental example, the energization amount to the proportional solenoid 30 is about 25%. When the amount is high, the fluid pressure PA at the output port A increases in proportion to the amount of energization to the solenoid, and the amount of energization increases from about 10 to
25% indicates that the fluid pressure PB at the output port B decreases in proportion to the amount of current supplied to the solenoid.

FIG. 8 shows the pressurizing force of the fluid pressure cylinder 1, the fluid pressure PA of the drive side pressure chamber 2, and the fluid pressure PB of the return side pressure chamber 3 when the amount of current applied to the proportional solenoid 30 is 95% of the maximum amount of current applied. This shows the change over time. As is clear from the figure, before the fluid pressures PA and PB reach a certain pressure, the differential pressure between them, in other words, the pressurizing force of the fluid pressure cylinder is kept almost constant, and therefore the fluid pressure cylinder is The time required to reach the pressing force of 1 is significantly shortened.

FIGS. 9 to 12 show modifications of the first embodiment, and each figure shows a state corresponding to FIGS. 3 to 6, respectively. This modification has the same structure and function as the first embodiment except that the spool 40 is an output port switching spool having four lands, so the same reference numerals are given in the drawings and a detailed explanation will be provided. is omitted.

FIG. 13 shows a second embodiment of the present invention. This second embodiment includes a pilot-operated valve section 41, a drive section 42, and a base 43, and the drive section 42 is controlled by the attraction force between the cores of the coil. The electro-pneumatic pyro valve includes a proportional solenoid that is proportional to the amount of current applied to the proportional solenoid, and a pilot valve section that outputs a pilot fluid pressure that is proportional to the amount of current applied to the proportional solenoid.

On the other hand, the valve part 41 is provided with a cylinder part 45 between the second feedback chamber 38 and the drive part 42, and the cylinder 45 is connected to a pilot fixed to the tip of a shaft rod passing through the second feedback chamber 38. The piston 46 divides the chamber into a pilot chamber 47 and a breathing chamber 4, with the pilot chamber 47 communicating with the output port of the electropneumatic pilot proportional valve in the drive unit 42, and the breathing chamber 48 communicating with the outside air. Also,
A pilot passage 49 is provided in the valve portion 41 to supply pilot fluid from the supply port P in the base 43 to the drive portion 42 .

Since the other configuration of the second embodiment is substantially the same as that of the first embodiment, the same or corresponding parts in the drawings are denoted by the same reference numerals, and detailed description thereof will be omitted. Further, the operation of the second embodiment is the same as that of the first embodiment except that the spool 20 is driven by pilot fluid pressure.

FIG. 14 shows a modification of the second embodiment, in which the spring seat 5
1 is made to protrude toward the cover 23 side, and the protruding portion 52 is
l Bias port 5 protruding into the feedback chamber 25
3 is screwed in airtightly, and a return spring 26 is compressed between the tip of the bias port 53 and the spool 20. By moving the bias port 53 forward and backward relative to the spring seat 51, the biasing force of the return spring 26 is increased to X18Ii! It is fixed in any position by a lock nut 54.

The other structure and operation of the above modification are the same as those of the second embodiment except that the biasing force fk of the return spring 26 is adjustable.

FIG. 15 shows a third embodiment of the present invention, and a valve section 61 of this third embodiment has a differential pressure chamber 62 formed at the end of the spool 20 opposite to the drive section 42, and the differential pressure The chamber includes a differential pressure piston 6 fixed to a shaft rod 63 integrated with the spool 20.
4 into a first feedback chamber 65 and a second feedback chamber 66, and a return spring 67 is compressed within the first feedback chamber 65.

Since the other configurations and operations of the third embodiment are the same as those of the second embodiment, the same reference numerals are given in the drawings and detailed explanations are omitted.

[Effects of the Invention] The present invention is capable of supplying and discharging pressure fluid to an actuator and maintaining the fluid pressure at a desired pressure using an electropneumatic proportional valve operated by a single solenoid. A valve for driving an actuator that is required to maintain a constant acting force can be made inexpensive.

In addition, the fluid pressure of the output port is applied to the feedback chamber attached to the spool, and the spool is displaced by the difference in fluid pressure, so that the differential pressure between the output ports is kept constant. Responsiveness can be significantly improved.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view of essential parts of the first embodiment of the present invention, FIG. 2 is a circuit diagram of the same as the above, FIGS.
The figure is a diagram showing the relationship between the amount of energization and the set output pressure, Figure 8 is a diagram showing changes in the pressurizing force of the drive side and return side pressure chambers and the actuator, and Figures 9 to 12 are diagrams showing the relationship between the energization amount and the set output pressure. Fig. 13 is a longitudinal sectional front view of the main part of the second embodiment of the present invention, Fig. 14 is a longitudinal sectional front view of the main part of the modification of the second embodiment, and Fig. 15 is the main part of the modification of the second embodiment of the present invention. FIG. 16, which is a longitudinal sectional front view of the main part of the third embodiment of the invention, is a control circuit diagram of a conventional fluid pressure cylinder. 11. 41, 61... Valve part, 12, 42... Drive part, 15... Valve body, 16 and supply port, 17a
, 17b φ/output port. 18a, 18b - Discharge port, 20.40 Chamber/Spool, 25.38, 65.66 - Feed/suck chamber,
26.67-# Return spring, 30 war/proportional solenoid, 3
1. Fixed iron core, 32. Movable iron core, 3G, 37
...Feedback passage. Patent Applicant NISMC Corporation Figure 1 Figure 2 Figure 16 ()
<SS
To, Teitosei Yukusho (self-proposal) January 20, 1988, 1-: Commissioner of the Patent Office Kuro 1) Akio Yu 1, Display of $ 1980 Patent Application No. 180884 2, Invention Name: Electro-pneumatic proportional valve 3, person making the amendment Relationship to this case Patent applicant address: Shin [1-18-4, Minato-ku, Tokyo] Name: Susumu Omura, President and CEO of NISMC Corporation 4, Agent: 1130 Telephone: 343
) 13755 Address 1-9-1 Nishi-Shinjuku, Shinjuku-ku, Tokyo
No. 2 Vol. 6, Contents of the detailed explanation of the invention and simple amendments to the drawings in the specification subject to amendment (1) "Figure 18" stated in the second line of page 3 of the specification has been changed to "
Figure 17” is corrected. (2) The "amount of energization to" written in the first line of page 4 will be corrected to "amount of energization to the electro-pneumatic proportional valve 6." (3) The word "property ga" written on page 4, line 10 will be corrected to "property ga". (4) "Second output output" described on page 14, line 13 of the same
" is corrected to "2nd output port". (5) The "95% of the current flow rate" stated in the first line of page 16 will be corrected to "approximately 60% of the power flow rate." (6) Same page 18: ``The present invention'' written in line 18 of jIJ and line 16 of page 18 is amended to ``r the present invention''. (7) The following statement will be inserted between lines 8 and 9 on page 19. 16A and 16B show an example in which the driving speed of the cylinder is controlled by a circuit similar to that shown in FIG.
When the amount of current ic is larger than a certain amount determined by ic, the cylinder accelerates, and when it is smaller, the cylinder is decelerated. Further, the pressurizing force at the stroke end of the cylinder can be arbitrarily controlled by the difference ie between the amount of current applied to the proportional solenoid 30 and the constant amount of current ic. In the above embodiment, since the cylinder is driven by one solenoid, the cylinder, forward and backward movement, acceleration and deceleration can be controlled by the amount of current applied to the solenoid, and moreover, compared to deceleration by a throttle, pounding occurs due to an increase in back pressure. Since this does not occur, deceleration can be achieved smoothly. ” (8) “Figure 16” written on page 20, line 15 of the same
Are rm16 diagrams A and B normal? Figure 17, a diagram showing the relationship between Itffi and output pressure, is corrected as follows. (9) Correct the drawings Figure 1, Figure 8, Figure 13, Figure 15, and JIS diagram as shown in the attached sheet. (1G) Figure 17 of the drawing is added as shown in the attached sheet. Figure 1 Figure 16 Figure 17 Procedural amendment (voluntary) February 3, 1988 1. Display of 3S Showa S1 Patent Application No. 180864 2 Name of invention Electro-pneumatic proportional valve 3 Make amendments Relationship with the patent case Patent applicant address 1-18-4 Shinbashi, Minato-ku, Tokyo Name Susumu Omura, President and CEO of NISMC Corporation 4, Agent Address: 180 Telephone: (343) 8
755 Address: 1-9-12, Nishi-Shinjuku, Shinjuku-ku, Tokyo. ／〆）＼ Contents of the amendment (1) The term ``cylinder and'' written on page 2, line 1 O of the written amendment submitted on January 20, 1986 will be amended to read ``of the cylinder.''

Claims (1)

[Claims] 1. A valve including a valve member for switching a flow path between each port in a valve body having a supply port, first and second output ports, and first and second discharge ports. a drive unit that applies a driving force to one end of the valve member; and a return spring that applies a return force to the other end of the valve member; By displacing the member, one of the supply ports and the output port and the other of the discharge port and the output port are brought into communication with each other, and the supply port is closed so that the first or second output port can communicate with the discharge port in a constricted state. The valve body is configured as a 5-port valve, and the valve body has first and second feedback chambers that apply feedback fluid pressure to the valve member in the drive and return directions, and these feedback chambers communicate with each output port. the driving section is configured by a driving force generating means that outputs a driving force proportional to the amount of electricity energized to the proportional solenoid to the valve member. Electropneumatic proportional valve.