KR101663799B1 - Electrohydrolic power cylinder actuator with air vent valve - Google Patents

Abstract

[0001] The present invention relates to an electro-hydraulic actuator capable of discharging air, comprising a first port through which hydraulic fluid is supplied, a second port through which air is discharged, and a third port through which air is circulated, A servo valve part that is mounted and guided through a bracket part provided on the outer side of the cylinder part and supplies hydraulic oil to the inside of the cylinder part to pressurize the piston part to thereby control the actuator drive; An output section connected to the piston section and outputting a driving force; and a second rod end cap provided in the first rod end cap of the cylinder section, An air discharge valve for discharging the air inside the cylinder to the outside through the second port provided in the end cap Wherein the air discharge valve comprises a valve body having a body portion and a discharge flow passage, the discharge flow passage being connected to the second port to discharge the air in the cylinder to the outside, a valve body accommodated in the valve body, A valve spool disposed inside the valve body and reciprocating within the valve spool; a valve elastic member disposed between the valve body and the valve spool for biasing the valve spool elastically; And a bridge that has a relatively larger clearance than the clearance between the body and the valve spool, and which is formed in a plurality of openings and acts to close the hydraulic oil flowing into the clearance.

Description

TECHNICAL FIELD [0001] The present invention relates to an electro-hydraulic actuator having an air discharge valve,

The present invention relates to an electric hydraulic actuator having an air discharge valve capable of discharging air inside hydraulic oil to the outside in an electric hydraulic actuator for drive control of a turbine of a power plant.

As is well known, a thermal power plant and a nuclear power plant are composed of a steam generator, a turbine that drives the generator with steam, a generator system, a cooling system, and the like. By operating the steam valve to regulate the amount of steam supplied to the turbine Power generation can be controlled.

Here, the supply of steam to the turbine or the interruption of the steam during braking of the turbine is accomplished by operation of the steam valve, which may be driven by a hydraulic actuator system controlling the turbine steam valve.

Meanwhile, steam turbines installed in thermal power plants and nuclear power plants are composed of a high-pressure turbine and a low-pressure turbine. Steam discharged from the high-pressure turbine and steam flowing into the low-pressure turbine and turbine is controlled by the turbine governor control system equipment .

Here, the turbine governor control system facility apparatus is constituted by turbine valves for regulating the pressure and steam amount of the steam and hydraulic actuators for providing driving force to the turbine valves. By operating these turbine valves and hydraulic actuators, The flow rate can be adjusted to control the rotational speed load of the steam turbine.

The hydraulic actuator that provides the driving force to the turbine valve is composed of a piston that reciprocates linearly according to supply and discharge of the hydraulic oil supplied and recovered, and a cylinder that receives and discharges the hydraulic oil. And a piston rod connecting between the piston head and the valve, and the hydraulic actuator can be operated in accordance with supply and discharge of the hydraulic oil to one side of the piston head.

However, when the hydraulic actuator is provided with a pressing force by hydraulic oil on one side of the piston head, vibration, noise, or the like occurs when incompressible hydraulic oil and compressible air are combined and cavitation occurs. And the seal is damaged.

Registered Patent Publication No. 10-1343640 (Announcement of Dec. 20, 2013): Hydraulic Servo Actuator of Steam Valve for Turbine Control of Nuclear and Thermal Power Plant Employing Hydraulic Dynamic Bearing

According to the present invention, cavitation caused by vibration and noise generation can be prevented by discharging air contained in hydraulic oil in a hydraulic oil receiving space of an electrohydraulic actuator, and maintenance cost of a product due to such breakage prevention can be reduced And to provide an electrohydraulic actuator having an air discharge valve.

The objects of the embodiments of the present invention are not limited to the above-mentioned objects, and other objects not mentioned can be clearly understood by those skilled in the art from the following description .

According to an embodiment of the present invention, there is provided a hydraulic pump comprising: a cylinder having a first port through which hydraulic fluid is supplied, a second port through which air is discharged, and a third port through which air is circulated, A servo valve part mounted and guided through a bracket part provided on the outer side of the cylinder part to supply the hydraulic oil to the cylinder part to pressurize the piston part to control the actuator driving, and a piston head and a piston rod A piston portion inserted into the cylinder portion and driven according to the hydraulic oil supplied from the servo valve portion, an output portion connected to the piston portion and outputting a driving force, and a second rod end cap And a second port provided in the first rod-end cap for discharging the air in the cylinder to the outside through the second port, Wherein the air discharge valve includes a body portion and a discharge flow passage, the discharge passage is connected to the second port to discharge the air in the cylinder to the outside, and a valve body A valve spool for reciprocating within the valve body by the hydraulic oil; a valve elastic member disposed between the valve body and the valve spool to elastically bias the valve spool; A valve body and a valve spool, the valve body and the valve spool being spaced apart from each other by a gap larger than a clearance between the valve body and the valve spool, An electrohydraulic actuator having a discharge valve may be provided.

According to the present invention, cavitation caused by vibration and noise generation can be prevented in advance by discharging the air remaining in the space above the cylinder before supplying the air and the hydraulic oil contained in the hydraulic oil in the hydraulic oil receiving space of the electrohydraulic cylinder actuator, It is possible to reduce the maintenance cost of the product due to such breakage prevention.

FIG. 1 and FIG. 2 illustrate an electrohydraulic actuator according to an embodiment of the present invention,
Figures 3A-3C illustrate a bushing in accordance with an embodiment of the present invention,
4 and 5 are views showing an air discharge valve of an electrohydraulic actuator according to an embodiment of the present invention in detail,
6 and 7 are cross-sectional views of an air discharge valve according to an embodiment of the present invention.

Advantages and features of embodiments of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. The following terms are defined in consideration of the functions in the embodiments of the present invention, which may vary depending on the intention of the user, the intention or the custom of the operator. Therefore, the definition should be based on the contents throughout this specification.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1 and 2 are views illustrating an electrohydraulic actuator according to an embodiment of the present invention. FIGS. 3A to 3C are views showing a bushing according to an embodiment of the present invention in detail. FIGS. FIGS. 6 and 7 are views showing an air discharge valve of an air discharge valve according to an embodiment of the present invention.

1 to 5, an electrohydraulic actuator according to an embodiment of the present invention includes a cylinder unit 100, a bracket unit 200, a servo valve unit 300, a piston unit 400, an output unit 500, An air vent valve 600, and the like.

The cylinder part 100 forms a space for receiving and discharging the hydraulic oil supplied from the servo valve part 300 to be described later, and forms a space to be driven by inserting the piston therein. The cylinder part 100 includes a cylindrical cylinder 110, End cap 120 and a second rod-end cap 130 are provided at both ends of the first rod-end cap 120. The first rod-end cap 120 and the second rod- And may include a bushing 140.

An elastic member 111 is provided on the inside of the cylinder 110 to support the lower portion of the piston head 410 so that the restoring force that can be restored to the original position after the piston head 410 is moved .

The first rod end cap 120 is coupled to close one end of the cylinder 110 and may have a first port 121 connected to the inside of the cylinder 110 at one side. The first port 121 may be supplied with hydraulic oil for pressing the piston unit 400 from the servo valve unit 300.

The second rod end cap 120 may include a second port 122 provided with an air discharge passage to the outside and an air discharge valve 600 connected to the second port 122. The air discharge valve 600 may be formed, Will be described later in detail.

The second rod end cap 130 is coupled to seal the other end of the cylinder 110 and may have a third port 131 connected to the inside of the cylinder 110 at one side. The third port 131 may be connected to the oil tank so that the discharged air in the upper portion of the piston 400 and the oil leaking from the piston head 410 are collected into the oil tank.

Here, the first connection hose (a) for collecting the hydraulic oil leaked through the second port 122 provided in the first rod-end cap 120 into a separate oil tank (not shown) And a second connection hose b for collecting the hydraulic oil leaked through the third port 131 provided in the cap 120 into a separate oil tank. The first connection hose (a) and the second connection hose (b) may be connected to each other and extended to a separate oil tank.

The bushing 140 is provided at an engagement portion of the output portion 500 which is coupled to the outside of one end of the first rod end cap 120 to prevent eccentric movement of the output rod 510 provided at the output portion 500 .

The bushing 140 is provided with a discharge port for transferring hydraulic fluid leaking from the contact surface of the output rod 510 penetrating through the first lower end cap 120 to the second port 122 through the communicating flow path 122a, And a leakage check port 142 for checking whether or not there is leakage during operation may be connected to one end of the discharge passage 141. [

A plurality of stepped portions may be formed in the bushing 140. A dust seal may be coupled to the first step 143 formed at the upper portion of the bushing 140 to prevent leakage of the hydraulic fluid and contaminants from the outside. 143 may be coupled to a wearer for guiding the output rod 510 to prevent contact between the metals on the contact surface of the output rod 510 during the sliding movement, A rod seal for preventing leakage of hydraulic oil may be coupled to the third step 145 formed at the lower portion of the first step 144.

The bracket part 200 is provided outside the cylinder part 100 and guides the servo valve part 300. The bracket part 200 includes a bracket 210 provided outside the cylinder 100, And a connection block 220 on which the unit 300 is mounted.

The servo valve unit 300 controls the driving of the actuator by supplying hydraulic oil to the inside of the cylinder unit 100 to press the piston unit 200. The servo valve unit 300 includes a pressure port and a supply port And the servo valve unit 300 of the prior art can be applied to the servo valve unit, so that a detailed description thereof will be omitted.

The piston portion 400 is inserted into the cylinder portion 100 and driven (for example, forward, backward, etc.) in accordance with the hydraulic oil supplied or discharged from the servo valve portion 300 through the first port 121 Which may include a piston head 410, a piston stroke restricting portion 420, an eccentric retention portion 430, and the like.

This piston head 410 can be reciprocated in accordance with the hydraulic oil supplied or discharged from the servo valve unit 300 through the first port 121 and the piston stroke stopper 420 can be reciprocated in accordance with the stroke of the piston head 410 And an output rod 510 is fixedly coupled to the piston head 410 to extend to the other end.

The eccentric bearing portion 430 is provided on the outer surface of the piston head 410 contacting the inner surface of the cylinder 110 and distributes the lateral pressure applied to the cylinder 110 according to supply and discharge of the hydraulic oil, It is possible to prevent the eccentric movement of the piston head 410 and prevent uneven wear of the piston head 410.

The output unit 500 is connected to the piston unit 400 and outputs the driving force of the piston unit 400. The output unit 500 includes an output rod 510 connected to the piston head 410 and an output rod connected to the output rod 510. [ It is possible to output the driving force of the piston unit 400 including the block 520. This driving force allows the valve to open and close the steam and fluid supply passages.

The air discharge valve 600 is provided in the first rod-end cap 120 of the cylinder part 100 to discharge the air inside the cylinder 110 to the outside. The valve body 610, the valve spool 620, A valve elastic member 630, a bridge 640, and the like. Here, the air discharged from the inside to the outside of the cylinder 110 by the air discharge valve 600 may include air in the cylinder 110 and air contained in the hydraulic oil.

The valve body 610 accommodates the valve spool 620 and the valve elastic member 630 therein and has an internal length formed to have a length that is the sum of the length of the valve spool 620 and the movement distance of the valve spool 620 .

The valve body 610 includes a body portion 611, a discharge passage 612 and a first stopping protrusion 613. The discharge passage 612 is connected to the second port 122, And discharges the internal air to the outside of the cylinder 110 through the second port 122.

The discharge passage 612 is connected to the orifice 613 through a first discharge passage 612a for discharging air and air contained in the hydraulic oil flowing through the bridge 640 to the outside of the cylinder 110 And a second discharge flow passage 612b. That is, the air inside the cylinder 110 and the air contained in the hydraulic oil are discharged to the outside of the cylinder 110 through the first and second discharge flow paths 612a and 612b.

The first stopping protrusion 613 is formed on the inner surface of the body portion 611 so as to be stepped so that the second stopping protrusion 624 formed on the outer surface of the spool body 621 is engaged with the spool body 621, It is possible to prevent and minimize the leakage of the hydraulic oil to the second discharge passage 612b.

The valve spool 620 reciprocates within the valve body 610 by hydraulic oil and can reciprocate between a first position communicating with the discharge passage 612 and a second position releasing the communication with the discharge passage 612 have. That is, the valve spool 620 moves up and down between the first position and the second position.

The valve spool 620 may include a spool body 621, an inflow conduit 622, an orifice 623 and a second retaining jaw 624 which are located within the valve body 610 And can reciprocate. Here, the sectional shape of the spool body 621 is constant, and the inside of the valve body 610 accommodating the spool body 621 can be formed corresponding to the sectional shape of the spool body 621. For example, the valve body 610 and the spool body 621 may be formed in a cylindrical shape having a concentric circle, and the valve body 610 and the spool body 621 may have various sectional shapes such as a cylindrical shape having the same center, .

The orifice 623 may be formed to communicate with the first discharge passage 612a through the inside of the cylinder 110. The orifice 623 may be formed in the cylinder 110, And the air contained in the hydraulic oil in the inflow passage 622 can be discharged to the second port 122. [ That is, the orifice 623 communicates with the first discharge flow passage 612a at the first position and the communication with the first discharge flow passage 612a at the second position.

The second stopping protrusion 624 is formed on the outer side of the spool body 621 so as to be engaged with the first stopping protrusion 613 to minimize leakage of the hydraulic oil to the second discharge flow passage 612b.

The valve elastic member 630 is disposed between the valve body 610 and the valve spool 620 to elastically bias the valve spool 620. The valve elastic member 630 is provided with a coil spring so that the valve spool 620 And may provide an elastic force to the valve spool 620 to move from the second position to the first position.

The bridge 640 is provided with a gap between the valve body 610 and the valve spool 620 at regular intervals in either the valve body 610 or the valve spool 620 along the moving direction of the valve spool 620 G, which are relatively larger than the gaps (G ') G, so that the hydraulic oil flowing into the gaps (G) can be acted upon.

When the valve spool 620 is positioned on the second position, the bridge 640 causes the hydraulic oil flowing into the gap G to act as an axle, and the bridge 640 is relatively more movable than the flow area of the gap G A pressure drop occurs in the hydraulic oil flowing from the gap G to the bridge 640. Since the air is smaller than the particles of the hydraulic oil and has a high velocity, the air can be continuously discharged to the second port 122 faster than the hydraulic oil by the throttle action on the bridge 640.

In addition, the plurality of bridge shoes 640 can sequentially drop the pressure along the flow direction of the hydraulic oil flowing into the gap G, and can guide the air and the hydraulic oil to the second discharge flow passage 612b, By providing the same pressure on the inner surface of the valve body 610 disposed between the gap G and the outer surface of the valve spool 620 so that the eccentricity of the valve spool 620 between the first and second positions The movement can be prevented.

The throttling portion receives the foreign matter contained in the hydraulic oil guided to the second discharge passage 612b through the gap G. The foreign matter flowing into the throttling portion can not flow into the gap G again, And prevents the foreign matter from flowing between the valve body 610 and the valve spool 620, thereby preventing a reduction in lubrication between the valve body 610 and the valve spool 620.

As shown in FIGS. 4 and 5, the bridge 640 may be formed in a rectangular shape, a circular shape, or the like. The bridge 640 is not limited to a specific shape, Sectional area larger than the cross-sectional area of the relatively large gap G ', or the gap G, as shown in Fig.

Therefore, by discharging the air contained in the hydraulic oil supplied from the hydraulic oil receiving space of the electrohydraulic actuator, it is possible to prevent cavitation due to vibration and noise generation, and to reduce the maintenance cost of the product due to such breakage prevention have.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be readily apparent that such substitutions, modifications, and alterations are possible.

100: cylinder part 200: bracket part
300: Servo valve part 400: Piston part
500: output unit 600: air discharge valve

Claims (8)

A cylinder portion having a first port through which hydraulic fluid is supplied, a second port through which air is discharged, and a third port through which air is circulated;
A servo valve part mounted and guided through a bracket part provided on the outside of the cylinder part to supply the hydraulic oil to the inside of the cylinder part to pressurize the piston part,
A piston portion including a piston head and a piston rod, the piston portion being inserted into the cylinder portion and driven according to the hydraulic oil supplied from the servo valve portion,
An output unit connected to the piston unit and outputting a driving force,
And an air discharge valve provided in the first rod end cap of the cylinder portion and discharging the air inside the cylinder through the second port provided in the first rod end cap,
The air discharge valve includes:
A valve body having a body portion and a discharge passage, the discharge passage being connected to the second port to discharge the air in the cylinder to the outside,
A valve spool received in the valve body and reciprocating inside the valve body by the hydraulic oil,
A valve elastic member disposed between the valve body and the valve spool to elastically bias the valve spool;
Wherein the valve body and the valve spool are spaced apart from each other at a predetermined interval along a moving direction of the valve spool, the valve body and the valve spool having a relatively larger clearance than a clearance between the valve body and the valve spool, Throttle school football
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The cylinder portion may include a bushing provided at an engagement portion of the output portion, which is coupled to the outside of one end of the first rod end cap, to block eccentric motion of the output rod provided at the output portion,
Wherein the bushing includes a discharge passage for transferring hydraulic fluid leaking from a contact surface of the output rod penetratingly connected to the first lower end cap to the second port and a leakage check port for checking whether leakage has occurred during operation And an air discharge valve connected to one end of the discharge passage.
delete The method according to claim 1,
Wherein the valve body has an air discharge valve having an inner length formed to have a length that is the sum of the length of the valve spool and the movement distance of the valve spool, and a stepped first stopping protrusion formed on an inner surface thereof.
The method of claim 3,
Wherein the discharge passage includes a first discharge passage for discharging air through the orifice provided in the valve spool and a second discharge passage for guiding the air contained in the hydraulic oil flowing through the bridge to the outside of the cylinder An electrohydraulic actuator having a discharge valve.
5. The method of claim 4,
The valve spool reciprocates between a first position communicating with the discharge passage and a second position releasing the communication with the discharge passage. The valve spool reciprocates between the first position and the second position to prevent the hydraulic oil from leaking through the second discharge passage. And an air discharge valve in which a stepped second stopping jaw is formed corresponding to the first stopping jaw.
6. The method of claim 5,
Wherein the valve spool is provided with an inflow passage so that the hydraulic oil supplied to the cylinder flows back into the cylinder, and the orifice and the first discharge passage are in communication with each other through the air in the cylinder and the hydraulic oil contained in the inflow passage And an air discharge valve for discharging air to the second port.
The method according to claim 6,
Wherein the plurality of gears are formed so as to sequentially drop the pressure along the flow direction of the hydraulic oil flowing into the gap and to guide the air and the hydraulic oil to the second discharge flow passage, And an air discharge valve for providing the same pressure on an inner surface of the valve body and an outer surface of the valve spool to prevent eccentric movement of the valve spool between the first position and the second position.
8. The method of claim 7,
Wherein the bridge has an air discharge valve formed in a right angle or a circular shape.

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