JP5727647B1 - Hydraulic actuator assembly for power plant - Google Patents

Abstract

A hydraulic actuator assembly for a power plant capable of preventing equipment damage due to oil leakage is provided. A lateral direction of the piston in a reciprocating direction is formed so that hydraulic oil storage spaces 160 and 170 for providing fluid pressure to the piston 200 are formed and the hydraulic oil leaking from the hydraulic oil storage space is guided to the hydraulic oil storage unit. Are provided with a cylinder 100 that forms an oil leakage guide channel 190, and an air discharge valve 700 that is disposed on the piston and selectively discharges and adjusts the air and hydraulic oil in the hydraulic oil storage space. [Selection] Figure 1

Description

  The present invention relates to a power plant hydraulic actuator assembly, and more particularly to a power plant hydraulic actuator assembly that provides a driving force to a valve to supply and shut off steam to a turbine.

  In general, a steam turbine installed in a thermal power plant or the like includes a high-pressure turbine and a low-pressure turbine. The steam flowing into the high-pressure turbine and the low-pressure turbine and the steam discharged through the turbine are controlled by the equipment device of the turbine governor control system.

  Here, the equipment of the turbine governor control system includes a turbine valve that adjusts the pressure and flow rate of steam, and a hydraulic actuator that provides the turbine valve with a driving force. By operating the turbine valve and the hydraulic actuator, the pressure and flow rate of the steam are adjusted to adjust the rotational speed load of the steam turbine.

  On the other hand, a hydraulic actuator that provides driving force to a turbine valve is composed of a piston that reciprocates linearly according to the fluid pressure of supplied and recovered hydraulic oil, and a cylinder that stores the piston and stores and discharges hydraulic oil. Is done. That is, the piston of the hydraulic actuator is connected to the turbine valve, and the operation of the turbine valve is performed by the reciprocating movement of the piston according to the fluid pressure of the hydraulic oil supplied to the inside of the cylinder and discharged to the outside of the cylinder.

  However, the conventional hydraulic actuator has a problem in that the hydraulic oil stored in the cylinder can leak to the outside when the piston reciprocates in order to provide driving force to the turbine valve. There is a risk of fire due to hydraulic oil.

Korean Registered Patent Publication No. 10-0941373 (Hydraulic Actuator for Development Equipment and its Maintenance Method)

  An object of the present invention is to provide a hydraulic actuator assembly for a power plant having an improved structure so that hydraulic oil leaking from the inside of a cylinder when a piston is operated can be recovered.

  According to the present invention, there is provided a power plant hydraulic actuator assembly having a hydraulic oil reservoir for supplying and recovering hydraulic oil according to the present invention and operating a valve for selectively adjusting supply and shutoff of steam and fluid. A piston connected to the valve and reciprocatingly moving so as to open and close a supply path for steam and fluid; and a hydraulic oil storage space for providing fluid pressure to the piston, the hydraulic oil storage space The hydraulic oil leaking from the cylinder is disposed in the piston, and a cylinder that forms a leakage oil guide channel in a lateral direction of the reciprocating movement direction of the piston, so as to guide the hydraulic oil leaking from the hydraulic oil storage section. This is achieved by a hydraulic actuator assembly for a power plant comprising an air discharge valve for selectively discharging and adjusting air and hydraulic oil.

  Here, the cylinder includes a cylindrical cylinder body forming the hydraulic oil accommodating space, and first and second rod end caps disposed on both sides of the cylinder body, and the oil leakage guide channel May pass through the first and second rod end caps and be formed laterally in the reciprocating direction of the piston.

  The piston is disposed in the hydraulic oil storage space, reciprocates according to supply and discharge of hydraulic oil, and divides the hydraulic oil storage space into a first region and a second region, and the piston head, A piston rod connected to the piston head and linearly moved in conjunction with the reciprocating movement of the piston head, and the air discharge valve is disposed on the piston head, and includes the first region and the second region. It is possible to selectively discharge and adjust the air and hydraulic oil mixed in any one of the above to the other.

  The power plant hydraulic actuator assembly is disposed between the first and second rod end caps and the piston rod, respectively, and between the first and second rod end caps and the piston rod. A bushing for forming a communication channel for guiding oil leakage to the oil leakage guide channel may be further provided.

  Here, it is preferable that the bushing guides the reciprocating movement of the piston rod and prevents the eccentric movement of the piston rod.

  More preferably, the surface roughness of the piston rod may be relatively higher than the surface roughness of the bushing.

  The power plant hydraulic actuator assembly is disposed on the piston head, and distributes the lateral pressure applied to the piston head in the lateral direction of the piston in the reciprocating direction, thereby preventing the eccentric movement of the piston. A blocking unit may be further provided.

  The hydraulic actuator assembly for a power plant is connected to a free end of the piston rod and the body, and is linked to the inner side of the body so as to contact the inner side of the body and partition the internal space of the body from the outside. And checking the state of the elastic member housed in the body and providing elastic force to the rod connecting portion according to the reciprocating movement of the piston, and the elastic member housed in the body. And a housing part having an inspection window disposed on the body.

  Here, the housing part may further include an air circulation part disposed in the upper part of the housing part and the rod connecting part to circulate air inside and outside the body.

  The air discharge valve has a valve body formed with a discharge flow path for discharging air and hydraulic oil, and is disposed inside the valve body to form an orifice communicating with the discharge flow path. A valve spool that selectively operates according to a pressure state, and a valve elastic member that is disposed inside the valve body and provides an elastic force to the valve spool.

  On the other hand, when the hydraulic oil inside the cylinder is at a high pressure, the valve spool is positioned at a blocking position that blocks communication between the orifice and the discharge flow path so as to block discharge of air and hydraulic oil. be able to.

  In contrast, when the hydraulic oil inside the cylinder is at a low pressure, the valve spool is configured so that the air and the hydraulic oil are discharged from the blocking position by the elastic force provided from the valve elastic member. It can be located in the communication position which connects the said discharge flow path.

  Specific matters of other embodiments are included in the detailed description and the drawings.

  The effects of the hydraulic actuator assembly for a power plant according to the present invention are as follows.

  First, the hydraulic oil that leaks from the inside of the cylinder in response to the operation of the piston can be recovered, and the equipment that responds to the oil leak can be prevented from being damaged, so that the reliability of the product can be improved.

  Secondly, when supplying hydraulic oil for operating the piston, the mixed air can be discharged, thereby preventing the air from being compressed and preventing the sealing components from being damaged, thereby reducing the maintenance and repair costs of the product. .

1 is a first operational cross-sectional view of a hydraulic actuator assembly for a power plant according to an embodiment of the present invention. It is the 2nd operation sectional view of other hydraulic actuator assemblies for power plants in an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of “A” region shown in FIG. 1. FIG. 2 is an enlarged cross-sectional view of a “B” region shown in FIG. 1. It is a partial block diagram of the housing part shown in FIG. FIG. 3 is an enlarged first operation sectional view of a “C” region shown in FIG. 1. FIG. 7 is an enlarged second operation cross-sectional view of the “C” region shown in FIG. 1.

Mode for carrying out the invention

  Hereinafter, a hydraulic actuator assembly for a power plant according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a first operation sectional view of a hydraulic actuator assembly for a power plant according to an embodiment of the present invention. FIG. 2 is a second operation sectional view of another hydraulic actuator assembly for a power plant according to an embodiment of the present invention. 3 is an enlarged cross-sectional view of the “A” region shown in FIG. 1.

  Prior to the description, it will be made clear in advance that a valve operated by a hydraulic actuator assembly for a power plant according to an embodiment of the present invention is not shown.

  As shown in FIGS. 1 to 3, a hydraulic actuator assembly 10 for a power plant according to an embodiment of the present invention includes a cylinder 100, a piston 200, and an air discharge valve 700. The power plant hydraulic actuator assembly 10 according to the embodiment of the present invention includes an eccentricity prevention unit 300 (see FIG. 4), a cylinder sleeve 400 (see FIG. 4), a bushing 500, a housing unit 600, and a hydraulic oil storage unit. 900 is further provided.

  The cylinder 100 forms a hydraulic oil storage space that stores the hydraulic oil supplied from the hydraulic oil storage unit 900. The cylinder 100 of the present invention includes a cylinder body 110, a first rod end cap 130, a second rod end cap 150, and an oil leakage guide channel 190.

  The cylinder body 110 is provided in a cylindrical shape and forms the above-described hydraulic oil storage space in which hydraulic oil is stored. The first rod end cap 130 and the second rod end cap 150 are disposed on both sides of the cylinder body 110, respectively, and close the cylinder body 110 from the outside. In detail, the first rod end cap 130 is disposed at an upper portion of the cylinder body 110 and the second rod end cap 150 is disposed at a lower portion of the cylinder body 110 based on the drawings shown in FIGS. 1 and 2. The hydraulic oil storage space is divided into a first region 160 and a second region 170 according to the position of a piston head 210 described later. As shown in FIG. 1, the first region 160 is formed in the upper part of the piston head 210 when hydraulic oil is not supplied into the cylinder body 110. On the other hand, as shown in FIG. 2, the second region 170 is formed at a lower portion of the piston head 210 when the hydraulic fluid is supplied into the cylinder body 110 and the piston head 210 is raised. Here, the second region 170 contains hydraulic oil that provides fluid pressure to the piston head 210.

  The oil leakage guide channel 190 guides the hydraulic oil storage unit 900 when the hydraulic oil in the second region 170 leaks from the first and second rod end caps 130 and 150 according to the reciprocation of the piston 200. That is, the oil leakage guide channel 190 is provided to collect the hydraulic oil leaking outside the cylinder 100 in the hydraulic oil storage unit 900. The oil leakage guide channel 190 of the present invention is formed through the first rod end cap 130 and the second rod end cap 150 in the lateral direction of the reciprocating movement direction of the piston 200, respectively. The oil leakage guide channel 190 is substantially formed in the cylinder body 110 along the length direction, and guides the leaked hydraulic oil to a channel (not shown) connected to the hydraulic oil storage unit 900. Such connection between the oil leakage guide flow path 190 and the flow path is merely an embodiment, and the oil leakage guide flow path 190 may extend to be connected to the hydraulic oil storage unit 900.

  The piston 200 is connected to a valve and reciprocates so that the valve opens and closes a steam and fluid supply path. The piston 200 reciprocates to provide a driving force that operates the valve. The piston 200 of the present invention includes a piston head 210 and a piston rod 230.

  The piston head 210 is disposed in the hydraulic oil storage space, and reciprocates according to the supply and discharge of the hydraulic oil. As described above, the piston head 210 divides the hydraulic oil accommodation space into the first region 160 and the second region 170 in accordance with the supply and discharge of the hydraulic oil. Specifically, the piston head 210 divides the hydraulic oil accommodation space into a first region 160 and a second region 170 according to its movement. An air exhaust valve 700 is disposed in the piston head 210 along the moving direction of the piston head 210. The piston rod 230 is disposed between the piston head 210 and the valve. The piston rod 230 is linearly moved in conjunction with the reciprocating movement of the piston head 210. The hydraulic oil leaking from the hydraulic oil storage space flows to the piston rod 230, and such hydraulic oil is guided to the above-described oil leakage guide channel 190.

  4 is an enlarged cross-sectional view of the “B” region shown in FIG. 1, and FIG. 5 is a partial configuration diagram of the housing portion shown in FIG.

  As shown in FIGS. 4 and 5, the eccentric prevention unit 300 is formed on the outer surface of the piston head 210 that is in contact with the cylinder 100, that is, the piston head 210 that is substantially in contact with the cylinder sleeve 400 according to an embodiment of the present invention. Located on the outer surface. The eccentricity prevention unit 300 disperses the lateral pressure applied to the piston head 210 according to the supply and discharge of hydraulic oil, and prevents the eccentric movement of the piston 200. Thus, since the eccentric prevention part 300 prevents the eccentric movement of the piston head 210, there exists an advantage that the eccentric wear of the piston head 210 can be prevented.

  The cylinder sleeve 400 is disposed between the inner wall of the cylinder body 110 and the outer surface of the piston head 210. The cylinder sleeve 400 is provided so that at least one of the wear can be prevented during frictional movement between the piston head 210 and the inner wall surface of the cylinder body 110. Since the cylinder sleeve 400 maintains a constant distance from the piston head 210, the wear of the piston head 210 can be prevented. Since the cylinder sleeve 400 substantially has a lower manufacturing cost than the cylinder 100 and the piston head 210, the maintenance and repair costs can be reduced by replacing the cylinder 100 or the piston head 210 during the maintenance and repair due to the occurrence of damage and wear.

  The bushing 500 is disposed between the first rod end cap 130 and the piston rod 230 and is disposed between the second rod end cap 150 and the piston rod 230. That is, two bushings 500 of the present invention are provided so as to be disposed in the regions of the first rod end cap 130 and the second rod end cap 150, respectively. The bushing 500 maintains an interval from the piston rod 230 to prevent the eccentric movement of the piston rod 230. Here, the bushing 500 is provided so as to have a surface roughness lower than the surface roughness of the piston rod 230. As described above, since the surface roughness of the bushing 500 is lower than the surface roughness of the piston rod 230, wear due to the frictional force between the bushing 500 and the piston rod 230 occurs on the contact surface of the bushing 500, thereby maintaining the bushing 500. By replacing the bushing 500 whose manufacturing cost is lower than that of the piston rod 230 at the time of repair, there is an advantage that maintenance and repair costs can be reduced.

  On the other hand, the bushing 500 of the present invention includes a bushing body 510 and a communication channel 530. The bushing body 510 forms the appearance of the bushing 500 and is disposed between the first and second rod end caps 130 and 150 and the piston rod 230, respectively, and maintains a constant distance from the piston rod 230. As described above, the inner wall surface of the bushing body 510 is manufactured to have a lower surface roughness than the outside of the piston rod 230. The communication channel 530 is formed through the bushing body 510. The communication channel 530 guides oil leakage between the first and second rod end caps 130, 150 and the piston rod 230 to the oil leakage guide channel 190.

  Next, the housing part 600 includes a body 610, a rod connecting part 630, an elastic member 650, an inspection window 670, and an air circulation part 690 as an embodiment of the present invention. The housing part 600 is disposed between the cylinder 100 and the valve.

  The body 610 forms the appearance of the housing part 600. The rod connecting portion 630 is connected to the free end of the piston rod 230 and interlocked with the reciprocating movement of the piston rod 230, and is in contact with the inside of the body 610 to partition the internal space of the body 610 from the outside. The elastic member 650 is accommodated in the body 610 and provides an elastic force to the rod connecting portion 630 according to the reciprocating movement of the piston 200. In detail, the elastic member 650 is compressed by the rod connecting portion 630 when the piston head 210 rises as the first operation, that is, when the piston head 210 rises due to the supply of the hydraulic oil, and the hydraulic oil is discharged to the outside of the cylinder 100 as the second operation. Then, an elastic force is provided to the rod connecting portion 630 so that the piston head 210 is lowered. The elastic member 650 may use various types of springs such as a coil spring or a plate spring.

  The inspection window 670 inspects the elastic member 650 disposed in the body 610 and accommodated in the body 610. The inspection window 670 is made of a transparent material so that the inside of the body can be inspected. The inspection window 670 is provided so as to check the state of the elastic member 650 accommodated in the body 610 and the accommodation state of moisture that can be generated due to a temperature difference between the inside and outside of the body 610 and the hydraulic oil that partially leaks. That is, the inspection window 670 is provided so as to inspect the fluid accommodation state and the corrosion and damage of the elastic member 650 described above.

  The air circulation unit 690 is disposed on the upper portion of the housing unit 600 and the rod connection unit 630, and circulates air inside and outside the body 610 or drains moisture and fluid stored in the body 610 to the outside. When a certain amount of moisture and fluid is stored in the body 610, the air circulation unit 690 drains moisture and fluid to the outside of the body 610 and maintains the same humidity in the body 610 as the outside. Thus, air inside and outside the body 610 is circulated so as to prevent corrosion of the elastic member 650. As described above, since the moisture and fluid stored in the body 610 can be drained to the outside of the body 610 by the air circulation unit 690, loss of components such as corrosion of the elastic member 650 can be prevented. There is an advantage.

  6 is an enlarged first operation sectional view of the “C” region shown in FIG. 1, and FIG. 7 is an enlarged second operation sectional view of the “C” region shown in FIG.

  As shown in FIGS. 6 and 7, the air discharge valve 700 is disposed on the piston 200 and selectively discharges and adjusts air and hydraulic oil in the hydraulic oil storage space. In particular, the air discharge valve 700 is disposed in the piston head 210 and selectively discharges and adjusts air and hydraulic oil mixed in one of the first region 160 and the second region 170 to the other one. To do. In detail, the air discharge valve 700 of the present invention discharges or regulates air and hydraulic oil from the second region 170 to the first region 160. The air discharge valve 700 discharges air and hydraulic oil to the first region 160 when the hydraulic oil supplied to the second region 170 is low pressure, and when the hydraulic oil supplied to the second region 170 is high pressure, The discharge of air and hydraulic oil to the first region 160 is adjusted. Here, the discharge adjustment of the air and the hydraulic oil means that the air and the hydraulic oil are cut off or partially discharged. A detailed description of the air exhaust valve 700 will be given later when the components of the air exhaust valve 700 are described.

  The air discharge valve 700 of the present invention includes a valve body 710, a valve spool 730, and a valve elastic member 750. The valve body 710 forms a discharge channel 712 that discharges air and hydraulic oil. A valve spool 730 and a valve elastic member 750 are accommodated in the valve body 710. The valve spool 730 selectively operates according to the pressure state of the hydraulic oil. Specifically, the valve spool 730 is moved up and down according to the pressure state of the hydraulic oil. A spool body 732 accommodated in the valve body 710, an inflow passage 734 through which air and hydraulic oil flow, and an orifice 736 communicating with the discharge passage 712 are provided. The valve elastic member 750 is disposed inside the valve body 710 and provides an elastic force to the valve spool 730. The valve elastic member 750 provides an elastic force to the valve spool 730 so as to lower the valve spool 730 that has been moved up and down.

  When the hydraulic oil in the cylinder 100 is at a low pressure, the valve spool 730 is positioned on a communication position where the discharge flow path 712 and the orifice 736 communicate. Thus, when the valve spool 730 is positioned on the communication position, the hydraulic oil is discharged to the first region 160 together with the air mixed in the second region or the hydraulic oil storage unit 900. When the valve spool 730 is in the communication position, air and hydraulic oil (where the hydraulic oil is not discharged to the first region 160 to provide hydraulic pressure to the piston head 210, but a small amount to discharge air. ), The loss such as O-ring corresponding to the compression of air in the second region 170 can be prevented.

  A process in which air and a small amount of hydraulic oil are discharged to the first region 160 in response to a continuous supply of hydraulic oil when the hydraulic oil inside the cylinder 100 is at a high pressure, when the hydraulic oil is substantially at a low pressure; The valve spool 730 is positioned on a blocking position where the valve spool 730 is raised by the fluid pressure of the hydraulic oil and blocks the orifice 736 and the discharge flow path 712. As the valve spool 730 moves to the shut-off position in this manner, the hydraulic oil is accommodated in the second region 170, whereby the hydraulic oil provides fluid pressure to the lower portion of the piston head 210, and the piston 200 moves. To come. In particular, when the hydraulic oil inside the cylinder 100 is at a high pressure, the air contained in the hydraulic oil is discharged.

  On the other hand, when the hydraulic oil in the second region 170 is collected in the hydraulic oil storage unit 900, the valve spool 730 is lowered from the shut-off position to the communication position described above by the elastic force of the valve elastic member 750. Such reciprocating movement between the shut-off position and the communication position of the valve spool 730 not only provides fluid pressure to the piston head 210 but also discharges mixed air, so that a sealing component such as an O-ring can be discharged. There is an advantage that it can prevent damage.

  The embodiments of the present invention have been described above with reference to the accompanying drawings. However, those who have general knowledge in the technical field to which the present invention pertains have changed their technical ideas and essential features of the present invention. It should be understood that the present invention can be implemented in other specific forms. Accordingly, it should be understood that the embodiments described above are illustrative in all aspects and not limiting. The scope of the present invention is defined by the following claims rather than the above detailed description, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof are defined in the present invention. If included in the range, it must be analyzed.

DESCRIPTION OF SYMBOLS 100 Cylinder 110 Cylinder body 130 1st rod end cap 150 2nd rod end cap 190 Oil leakage guide flow path 200 Piston 210 Piston head 230 Piston rod 300 Eccentricity prevention part 500 Bushing 530 Communication flow path 600 Housing part 610 Body 630 Rod connection part 650 Elastic member 670 Inspection window 690 Air circulation part 700 Air discharge valve 710 Valve body 712 Discharge flow path 730 Valve spool 736 Orifice
750 Elastic member 900 Hydraulic oil reservoir

Claims (12)

A hydraulic actuator assembly for a power plant having a hydraulic oil reservoir for supplying and recovering hydraulic oil and operating a valve for selectively adjusting supply and shutoff of steam and fluid,
A piston connected to the valve and reciprocatingly moving the valve to open and close a steam and fluid supply path;
An oil leakage guide is formed in a lateral direction of the reciprocating direction of the piston so as to form a hydraulic oil storage space for providing fluid pressure to the piston and to guide the hydraulic oil leaking from the hydraulic oil storage space to the hydraulic oil storage unit. A cylinder forming a flow path;
A hydraulic actuator assembly for a power plant, comprising: an air discharge valve disposed on the piston for selectively discharging and adjusting air and hydraulic oil in the hydraulic oil storage space. The cylinder includes a cylindrical cylinder body that forms the hydraulic oil storage space, and first and second rod end caps disposed on both sides of the cylinder body,
2. The hydraulic actuator for a power plant according to claim 1, wherein the oil leakage guide flow path is formed in a lateral direction of the piston in a reciprocating direction through the first and second rod end caps. Assembly. The piston is disposed in the hydraulic oil storage space, reciprocates according to supply and discharge of hydraulic oil, and divides the hydraulic oil storage space into a first region and a second region, and the piston head, A piston rod connected to the piston head and linearly moved in conjunction with the reciprocating movement of the piston head;
The air discharge valve is disposed in the piston head, and selectively discharges and adjusts air and hydraulic oil mixed in any one of the first region and the second region to the other one. The hydraulic actuator assembly for a power plant according to claim 2, wherein: The hydraulic actuator assembly for a power plant is
Oil leakage between the first and second rod end caps and the piston rod is guided between the first and second rod end caps and the piston rod to the oil leakage guide channel. The hydraulic actuator assembly for a power plant according to claim 3, further comprising a bushing that forms a communication flow path.   5. The hydraulic actuator assembly for a power plant according to claim 4, wherein the bushing guides reciprocal movement of the piston rod and prevents eccentric movement of the piston rod. 6.   6. The hydraulic actuator assembly for a power plant according to claim 4, wherein a surface roughness of the piston rod is relatively higher than a surface roughness of the bushing. The hydraulic actuator assembly for a power plant is
The apparatus further comprises an eccentricity prevention unit disposed on the piston head and configured to disperse a lateral pressure applied to the piston head in a lateral direction in a reciprocating direction of the piston to prevent an eccentric movement of the piston. Item 4. The hydraulic actuator assembly for a power plant according to Item 3. The hydraulic actuator assembly for a power plant is
A body, coupled to a free end of the piston rod, interlocked to move, contacted with the inside of the body, and accommodated inside the body, a rod coupling part that partitions the internal space of the body from the outside, An elastic member for providing an elastic force to the rod connecting portion according to the reciprocating movement of the piston, and an inspection window disposed in the body so as to inspect the state of the elastic member housed in the body. The hydraulic actuator assembly for a power plant according to claim 3, further comprising a housing portion having the same. The housing part is
9. The hydraulic actuator assembly for a power plant according to claim 8, further comprising an air circulation part disposed in the upper part of the housing part and the rod connecting part for circulating air inside and outside the body. The air discharge valve is
A valve body formed with a discharge passage for discharging air and hydraulic oil;
A valve spool disposed inside the valve body, forming an orifice communicating with the discharge flow path, and selectively operating according to a pressure state of the hydraulic oil;
The hydraulic actuator assembly for a power plant according to claim 3, further comprising: a valve elastic member that is disposed inside the valve body and provides an elastic force to the valve spool.   When the hydraulic oil inside the cylinder is at a high pressure, the valve spool is positioned at a blocking position that blocks communication between the orifice and the discharge channel so as to block discharge of air and hydraulic oil. The hydraulic actuator assembly for a power plant according to claim 10, wherein the hydraulic actuator assembly is a power plant.   When the hydraulic oil inside the cylinder is at a low pressure, the valve spool is configured to discharge the air and the hydraulic oil from the blocking position by the elastic force provided from the valve elastic member. The hydraulic actuator assembly for a power plant according to claim 11, wherein the hydraulic actuator assembly is located at a communication position communicating with the road.

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