Anti-rotation mechanism of electro-hydraulic actuator for steam turbine electric regulation

Abstract

The present invention provides an anti-rotation mechanism for an electro-hydraulic actuator used for electric control of a steam turbine. The key features of the mechanism are: an anti-rotation mechanism is installed on each of the front and rear sides of the actuator; each anti-rotation mechanism comprises an anti-rotation bracket with its inner end fixed to a base and its outer end formed as an ear plate, with the holes in the anti-rotation bracket ear plates being screw holes; a disc spring support with its inner end fixed to the electro-hydraulic actuator and its outer end formed as an ear plate, the disc spring support ear plate and the anti-rotation bracket ear plate being arranged in an inner and outer direction in the X-direction; a guide rod with a polished inner section and a screw rod as its outer section, which engages with the screw holes in the anti-rotation bracket ear plates; a disc spring mounted on the polished rod section of the guide rod and positioned between the two ear plates; an adjusting nut, which engages with the screw rod, is located between the disc spring and the anti-rotation bracket ear plates; the adjusting nut and the disc spring support ear plates serve as disc spring seats. This mechanism has the positive effect of preventing relative rotation between the piston rod and the joint body, thereby extending the service life of the electro-hydraulic actuator-type steam turbine valve control system.

Description

Technical Field

[0001] The present invention relates to an electro-hydraulic regulating system for a steam turbine, in particular to a tripod-type steam distribution mechanism. Background Art

[0002] CN 105041390 A discloses an integrated electro-hydraulic actuator-type steam turbine valve adjustment system. The electro-hydraulic actuator 6 serves as a lever drive device and is fixed in a slot of a slot-shaped bracket 1. The lower end of the bracket is mounted on a base 10 via a hinge shaft 9. The upper end of the electro-hydraulic actuator's piston rod 61 is hinged to the power point 22 of a tripod-type lever 2. The direction of motion of the electro-hydraulic actuator's piston rod is defined as the Z direction, the axial direction of the hinge shaft is defined as the Y direction, and the direction perpendicular to the Y direction is defined as the X direction. The X and Y directions are both on the same horizontal plane. Because the electro-hydraulic actuator's center of gravity is not on the axis of the tripod and the base hinge shaft 9, and is affected by field vibration, when the electro-hydraulic actuator is driven by the turbine body and experiences acceleration in the X or Y direction, the electro-hydraulic actuator (main body) is subjected to a torque causing it to rotate about the piston rod axis. If the torque is too large, the piston rod of the electro-hydraulic actuator and the joint body will rotate relative to each other. The consequences are that, at the very least, the normal operation of the electro-hydraulic actuator will be affected (the pre-set values of the fully open position and the fully closed position deviate from the actual values); at the worst, the piston rod of the electro-hydraulic actuator will be completely disengaged from the joint body, causing the electro-hydraulic actuator to completely tip over, damaging the electro-hydraulic actuator and causing a turbine shutdown accident. Summary of the Invention

[0003] In order to solve the above technical problems, the purpose of the present invention is to provide an anti-rotation mechanism of an electro-hydraulic actuator for electric regulation of a steam turbine.

[0004] The object of the present invention is achieved in that it includes a base and an electro-hydraulic actuator, characterized in that: an anti-rotation mechanism is respectively installed on the front and rear sides (in the Y direction) of the electro-hydraulic actuator; each anti-rotation mechanism is that the inner end of the anti-rotation bracket is fixed to the base, the outer end is an ear plate, and the hole on the anti-rotation bracket ear plate is a screw hole; the inner end of the disc spring support is fixed to the electro-hydraulic actuator body, the outer end is an ear plate, the disc spring support ear plate and the anti-rotation bracket ear plate are arranged inside and outside in the X direction as a guide rod support (that is, the axial direction of the guide rod is in the X direction); the inner section of the guide rod is a smooth rod and the outer section is a screw rod, which cooperates with the screw hole on the anti-rotation bracket ear plate, and a locking nut is provided on the outer side of the anti-rotation bracket ear plate to lock the guide rod, the disc spring is installed in the smooth rod section of the guide rod and is located between the two ear plates, and an adjusting nut that cooperates with the screw rod is provided between the disc spring and the anti-rotation bracket ear plate, and the adjusting nut and the disc spring support ear plate serve as a disc spring seat.

[0005] When the electro-hydraulic actuator body is driven by the turbine body and has acceleration in the X or Y direction, due to the presence of disc springs on the front and rear sides, the electro-hydraulic actuator body is subjected to a counter torque, which balances or offsets the torque caused by the acceleration in the X or Y direction and suppresses its large rotation.

[0006] Compared with the prior art, the present invention has the following positive effects: it avoids relative rotation and disengagement between the piston rod and the joint body, thereby avoiding turbine shutdown accidents; and it prolongs the service life of the electro-hydraulic actuator. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The present invention will be further described below with reference to the accompanying drawings.

[0008] Figure 1 It is a schematic diagram of the present invention.

[0009] Figure 2 yes Figure 1 Top view of . DETAILED DESCRIPTION

[0010] See also Figure 2 It includes a base 1 and an electro-hydraulic actuator 9, and an anti-rotation mechanism is installed on the front and rear sides (in the Y direction) of the electro-hydraulic actuator; each anti-rotation mechanism is, (see Figure 1 ) The inner end 22 of the anti-rotation bracket 2 is fixed on the base 1 (which is also the turbine body), and the outer end is an ear plate. The hole on the anti-rotation bracket ear plate 21 is a screw hole; the inner end 82 of the disc spring support 8 is fixed on the electro-hydraulic actuator body, and the outer end is an ear plate. The disc spring support ear plate 81 and the anti-rotation bracket ear plate 21 are arranged inside and outside in the X direction, serving as a guide rod support (that is, the axial direction of the guide rod is in the X direction); the inner section of the guide rod 13 is a smooth rod and the outer section is a screw rod, which cooperates with the screw hole on the anti-rotation bracket ear plate. A locking nut 3 is provided on the outside of the anti-rotation bracket ear plate to lock the guide rod. The disc spring 6 is installed on the smooth rod section of the guide rod and is located between the two ear plates 21 and 81. There is an adjusting nut 4 that cooperates with the screw rod between the disc spring and the anti-rotation bracket ear plate, and the adjusting nut and the disc spring support ear plate serve as a disc spring seat. When installing the disc springs, adjust the adjusting nut 3 to the appropriate position. To ensure the same pre-compression on the disc springs and, accordingly, the same disc spring pressure (F1 = F2) on the disc spring supports, adjust the adjusting nut 3 so that the distance between the two lugs in the front and rear anti-rotation mechanisms is equal, i.e., L1 = L3, and the length of the two disc springs is equal, i.e., L2 = L4. A transition ring 5 is placed between the adjusting nut 4 and the disc springs, and a large washer 7 is placed between the disc springs and the disc spring support lugs 81, connecting the two anti-rotation brackets.

[0011] When the electro-hydraulic actuator body is sequentially driven by the turbine control valve stem 12 and lever 11, experiencing acceleration in the X or Y direction, the presence of disc springs on its front and rear sides creates a counter-torque on the actuator body. This counteracts or offsets the torque caused by the X or Y acceleration, suppressing significant rotation and thus preventing relative rotation between the actuator piston rod and the joint body 10. During normal operation, the actuator body swings around hinge point A within an angle α. At the extreme swing position, the gap C between the hole in the disc spring support lug 81 and the disc spring guide rod remains greater than zero. This means that during normal operation, the anti-rotation mechanism does not constrain the actuator body. The force exerted on the actuator body by the Z-direction acceleration is parallel to the piston rod axis 14, preventing the actuator body from rotating around the piston rod axis.

Claims

1. An anti-rotation mechanism for an electro-hydraulic actuator used for electric regulation of a steam turbine, comprising a base and an electro-hydraulic actuator, wherein the upper end of the piston rod of the electro-hydraulic actuator is hinged to the power point of a tripod-type lever, and wherein: An anti-rotation mechanism is installed on each of the front and rear sides of the electro-hydraulic actuator; each anti-rotation mechanism is that the inner end of the anti-rotation bracket is fixed to the base, the outer end is an ear plate, and the hole on the ear plate of the anti-rotation bracket is a screw hole; The inner end of the disc spring support is fixed to the electro-hydraulic actuator body, and the outer end is an ear plate. The disc spring support ear plate and the anti-rotation bracket ear plate are arranged inside and outside in the X direction, serving as a guide rod support; the electro-hydraulic actuator body swings around the hinge point within the angle α range. When it swings to the extreme position, the gap between the hole of the disc spring support ear plate and the disc spring guide rod is always greater than zero, and the anti-rotation mechanism will not constrain the electro-hydraulic actuator body; the inner section of the guide rod is a smooth rod, and the outer section is a screw rod, which cooperates with the screw hole on the anti-rotation bracket ear plate. A locking nut is provided on the outer side of the anti-rotation bracket ear plate to lock the guide rod, and the disc spring is installed on the smooth rod section of the guide rod and is located between the two ear plates. An adjusting nut that cooperates with the screw rod is provided between the disc spring and the anti-rotation bracket ear plate, and the adjusting nut and the disc spring support ear plate serve as a disc spring seat; Adjust the adjusting nut so that the distance between the two ear plates in the front and rear anti-rotation mechanisms is equal and the length of the two disc springs is equal; set a transition ring between the adjusting nut and the disc spring, and set a large washer between the disc spring and the disc spring support ear plate; the two anti-rotation brackets are connected as one.

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