Electric actuator with safety limiting function and integrated valve group

Abstract

The invention belongs to the field of valve control, and particularly discloses an electric actuator with a safety limiting function and an integrated valve bank.The electric actuator comprises a driving assembly and a limiting assembly, and in the driving assembly, a torque motor is connected with a main gear through a motor transmission shaft so as to drive the main gear to rotate; the auxiliary gear is meshed with the main gear, and the auxiliary gear is connected to the top end of the trapezoidal screw through a flat key; the trapezoidal screw is in threaded connection with the trapezoidal nut, and the trapezoidal nut is connected with the stop valve ejector rod; in the limiting assembly, a limiting installation plate is installed on a valve body of the control valve set through a positioning bolt, and a limiting ring is connected to the tail end of a motor transmission shaft through a flat key. The limiting ring and the limiting mounting plate are in clearance fit, and the inner side of the limiting mounting plate and the outer side of the limiting ring are each provided with a limiting protrusion structure. Mechanical limiting is achieved, the valve bank structure is simplified, a limiting device and installation parts are integrated, the size and cost are reduced, and the safety and reliability of the control valve bank are improved.

Description

Technical Field

[0001] The present invention belongs to the field of valve control, and more specifically, relates to an electric actuator and an integrated valve group with safety limit. Background Art

[0002] The deep sea contains rich mineral resources, biological resources, chemical resources and renewable energy. A deep-sea submersible is an important professional equipment specifically used for underwater exploration, exploration and development in the underwater environment.

[0003] When the submersible operates in the deep-sea environment, many factors will cause dynamic changes in its gravity and buoyancy. For example, the weight increases after the manipulator takes samples, and the weight decreases after deploying equipment; the density of seawater changes in different deep seas and at different temperatures in different sea areas, which causes buoyancy changes; the overall structure deformation of the submersible under high external pressure conditions in the deep sea will also cause buoyancy changes, etc. In order to ensure that the submersible has a relatively stable operating attitude, a buoyancy adjustment system is required to adjust the balance between the gravity and buoyancy of the submersible.

[0004] The submersible adjusts the magnitude of its net buoyancy through the water injection and drainage conditions of the seawater buoyancy adjustment system. The seawater buoyancy adjustment system controls its water injection and drainage functions through a bridge circuit composed of stop valves. When injecting water, seawater enters the ballast tank from the marine environment through a filter, a seawater pump, a stop valve and a balance valve, increasing the weight of the submersible and causing the submersible to sink; when draining water, seawater is discharged from the ballast tank to the marine environment through a stop valve, a seawater pump, a balance valve and a filter, reducing the weight of the submersible and causing the submersible to float.

[0005] At present, the control valve group of the buoyancy adjustment system of deep-sea submersibles often adopts a hydraulic control method, and there is also a part that adopts an electric control method. The hydraulic control method requires an additional hydraulic system. The system leads the pressure to the control chamber of the buoyancy adjustment stop valve through an oil pump, a stop valve, and joints and pipelines, thereby controlling the opening and closing of the stop valve. This control method has a large volume and weight, high cost, and problems such as oil leakage and pollution. And for the electric control method adopted on some current submersibles, a torque motor is used to control the opening and closing of four stop valves through a gear set and a trapezoidal screw transmission device, and then control the water injection and drainage conditions of the system. This control method has more structural components in the gear set, and there is no limit protection mechanism for the gear set and the trapezoidal screw transmission. If the driving motor malfunctions and causes the motor to rotate too large an angle, it will cause serious extrusion deformation at the transmission of the trapezoidal screw and trapezoidal nut, and even serious failures such as screw breakage and thread fragmentation, resulting in a serious accident that the buoyancy adjustment system is no longer controllable.

[0006] Therefore, there is an urgent need for an electric actuator and an integrated valve group that can save space on the submersible and are safer and more reliable. Summary of the Invention

[0007] In view of the above defects or improvement requirements of the prior art, the present invention provides an electric actuator with a safety limit and an integrated valve group, aiming to improve the reliability and safety of the electric actuator of the control valve group.

[0008] To achieve the above object, according to one aspect of the present invention, there is provided an electric actuator with a safety limit for realizing the opening and closing control of each globe valve in the control valve group. The electric actuator includes a driving component and a limiting component, wherein:

[0009] The driving component includes a torque motor, a motor transmission shaft, a secondary gear, a main gear, a trapezoidal screw, and a trapezoidal nut. The torque motor is connected to the main gear through the motor transmission shaft to drive the main gear to rotate; the secondary gear meshes with the main gear, and the secondary gear is connected to the top end of the trapezoidal screw through a flat key; the trapezoidal screw is threadedly connected to the corresponding trapezoidal nut to transmit power, and the trapezoidal nut is used to connect the globe valve push rod.

[0010] The limiting component includes a limiting mounting plate and a limiting ring. The limiting mounting plate is used to be mounted on the valve body of the control valve group through positioning bolts, and the limiting ring is connected to the end of the motor transmission shaft through a flat key; there is a clearance fit between the limiting ring and the limiting mounting plate, and both the inner side of the limiting mounting plate and the outer side of the limiting ring have limiting convex structures.

[0011] As a further preference, a pair of first bearings are installed on both sides of the trapezoidal screw collar. The limiting mounting plate presses on the outer ring of the first bearing through positioning bolts to position the first bearing and apply a pre-pressure at the same time.

[0012] As a further preference, the first bearing is an angular contact ball bearing, and a pair of angular contact ball bearings are mounted face to face.

[0013] As a further preference, a second bearing is provided on the limiting mounting plate, and this second bearing is used to position the motor transmission shaft.

[0014] As a further preference, the limiting convex structures on the limiting mounting plate and the limiting ring are both fan-shaped, and the two fan-shaped angles are the same and concentric; the head and root of the limiting convex structure are both rounded.

[0015] As a further preference, the limiting mounting plate and the limiting ring are made of 17-4PH stainless steel, TC4 titanium alloy, or Stellite alloy.

[0016] As a further preference, an installation component is further included. The installation component includes a motor mounting plate and a gear set housing. The gear set housing is installed outside the secondary gear and the main gear and fixed on the valve body; the torque motor is installed on the gear set housing through the motor mounting plate.

[0017] As a further preference, a compensation pipe joint is provided on the outer cover of the gear set, and a pressure compensation pipe leading into the outer cover of the gear set is connected to the compensation pipe joint.

[0018] As a further preference, the installation assembly further includes a plug, the trapezoidal screw rod and the trapezoidal nut are both installed in the plug, and the plug guides the trapezoidal nut.

[0019] According to another aspect of the present invention, an integrated valve group is provided, which includes the above-mentioned electric actuator with safety limit and a control valve group; there are four sub-gears in the electric actuator, and correspondingly four trapezoidal screw rods and four trapezoidal nuts;

[0020] The control valve group includes four globe valves A, B, C, D and a balance valve; the inlet of the balance valve is connected to the outlet of the seawater pump, and the outlet of the balance valve is connected to the globe valves; the four globe valves are evenly distributed around the central axis of the torque motor, and the globe valves A, B, D, C are connected end to end in sequence to form a bridge circuit, and each globe valve is respectively connected to a trapezoidal nut; the globe valves A and D are placed opposite to each other, and the globe valves B and C are placed opposite to each other; the thread rotation directions of the trapezoidal screw rods and trapezoidal nuts corresponding to the oppositely placed globe valves are the same, and the thread rotation directions of the trapezoidal screw rods and trapezoidal nuts corresponding to the adjacently placed globe valves are opposite.

[0021] Generally speaking, compared with the prior art by the above technical solutions conceived by the present invention, the following technical advantages are mainly possessed:

[0022] 1. The present invention designs a limit device highly integrated with the installation components, which can provide reliable protection for the control valve group; specifically, the limit cooperation is realized through the limit protruding structure between the limit ring key-connected to the motor transmission shaft and the limit mounting plate installed on the valve body by positioning bolts, so as to protect the trapezoidal screw rod and the globe valve. Compared with the existing electric drive control mechanism, it is provided with an independent mechanical limit structure; in the case of misoperation or out-of-control of the motor, the locked-rotor torque of the torque motor in the traditional electric drive control mechanism will be applied between the trapezoidal screw rod and the trapezoidal nut and between the globe valve push rod and the globe valve spool, which may cause the trapezoidal screw rod to break, the trapezoidal thread to deform and break, and the globe valve push rod to swell and deform, resulting in the globe valve being stuck, etc.; in the case of motor locked-rotor, the limit structure between the limit ring and the limit mounting plate in the limit protection device of the present invention will bear all the locked-rotor torques and transmit them to the valve body through the positioning bolts, completely avoiding the above-mentioned failure situations and greatly improving the safety and reliability of the electric drive control valve group.

[0023] 2. In the present invention, the limit mounting plate serves both as a limiting device and cooperates with the limit ring to achieve the limit protection function; it also serves as a mounting component, and at the same time serves as the upper mounting surface of the trapezoidal screw positioning bearing and the lower mounting surface of the motor drive shaft positioning bearing. In addition, the limit mounting plate is installed on the valve body through positioning bolts. By adjusting the installation torque of the positioning bolts, the installation pre-pressure of the trapezoidal screw positioning bearing can be adjusted to ensure more accurate positioning accuracy and good stress conditions of the trapezoidal screw. The structure and function of the limit mounting plate are highly integrated, greatly simplifying the structure of the control valve group, reducing the number of installation parts of the control valve group, reducing the overall volume and weight, and at the same time reducing the assembly difficulty and the requirements for assembly accuracy.

[0024] 3. In the present invention, a pair of angular contact ball bearings are installed on both sides of the trapezoidal screw shaft ring, and the face-to-face installation method is adopted; the upper angular contact ball bearing mainly bears the axial thrust when the motor drives to open the stop valve and is positioned through the limit mounting plate; the lower angular contact ball bearing mainly plays a positioning and lubricating role, greatly improving the positioning accuracy of the trapezoidal screw and the auxiliary gear, and at the same time greatly reducing the friction force received by the end face of the trapezoidal screw, thereby reducing the torque required to drive the trapezoidal screw to rotate, and finally reducing the power and torque of the required torque motor.

[0025] 4. In the present invention, the limit protrusion structures of the limit ring and the limit mounting plate are fan-shaped structures, with the same fan angles and being concentric, so that the limit contact is a surface contact to reduce the contact stress during contact extrusion, ensuring that the limit ring and the limit mounting plate do not deform or collapse; at the same time, the head and root of the limit protrusion structure are both rounded to reduce the local stress during limit contact, avoiding stress concentration when the blocking torque is too large and resulting in tearing at the root.

[0026] 5. In the present invention, a hose is connected through a pressure compensation joint inside the gear set housing, so that through the method of filling oil inside, both the lubrication requirement can be met and pressure compensation can be carried out at the same time to achieve internal and external pressure balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a cross-sectional view of the integrated valve group structure of the embodiment of the present invention;

[0028] Figure 2 is a side cross-sectional view of the integrated valve group structure of the embodiment of the present invention;

[0029] Figure 3 is a schematic diagram of the structure of the limit device of the embodiment of the present invention;

[0030] Figure 4 is an enlarged view of the structure of the limit device of the embodiment of the present invention.

[0031] In all the figures, the same reference numerals are used to denote the same elements or structures, where: 1 - torque motor, 2 - motor mounting plate, 3 - motor transmission shaft, 4 - gear set housing, 5 - secondary gear, 6 - first bearing, 7 - trapezoidal screw, 8 - trapezoidal nut, 9 - main gear, 10 - bearing retainer ring, 11 - limit mounting plate, 12 - second bearing, 13 - limit ring, 14 - plug, 15 - valve body, 16 - positioning bolt, 17 - flat key. Detailed implementation mode

[0032] In order to make the objectives, technical solutions and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0033] An electric actuator with safety limit provided by an embodiment of the present invention is used to realize the opening and closing control of each stop valve in a control valve group. As Figure 1 and Figure 2 shown, the electric actuator includes a driving assembly, a limit assembly and a mounting assembly.

[0034] The driving assembly includes a torque motor 1, a motor transmission shaft 3, a secondary gear 5, a main gear 9, a trapezoidal screw 7 and a trapezoidal nut 8. The torque motor 1 is connected to the main gear 9 through the motor transmission shaft 3. The main gear 9 is connected to the motor transmission shaft 3 by a flat key. When the torque motor 1 rotates, torque is input to the gear set through the motor transmission shaft 3. The secondary gear 5 meshes with the main gear 9, and the secondary gear 5 is connected to the top end of the trapezoidal screw 7 by a flat key, and the torque transmitted by the main gear 9 is further transmitted to the trapezoidal screw 7. The trapezoidal screw 7 is threadedly connected to the corresponding trapezoidal nut 8 and transmits power. The trapezoidal nut 8 is connected to the stop valve push rod; through trapezoidal thread transmission, the rotation and torque of the trapezoidal screw 7 are converted into axial linear motion and axial force output.

[0035] The limit assembly includes a limit mounting plate 11 and a limit ring 13. The limit mounting plate 11 is mounted on the valve body 15 of the control valve group through a positioning bolt 16. The limit ring 13 is connected to the end of the motor transmission shaft 3 by a flat key 17 and is axially positioned by flat washers and screws. Both the inner side of the limit mounting plate 11 and the outer side of the limit ring 13 have limit convex structures.

[0036] Specifically, as Figure 3 and Figure 4As shown in the figure, there are limiting convex structures on the outer circle of the limiting ring 13 and on the inner circle of the limiting mounting plate 11. The convex structures at both places are fan-shaped structures, and the fan angles (i.e., the included angle between the two straight lines of the fan) are the same, and both are coaxial with the motor transmission shaft 3. When limiting protection occurs, the contact between the limiting convex structures is surface contact, which greatly reduces the contact stress between the two. The top and root of the limiting convex structures on the limiting ring 13 and the limiting mounting plate 11 are both large fillet structures (R0.5 - R0.8), which can greatly weaken the stress concentration phenomenon on the limiting convex structures and prevent the root of the fan-shaped limiting convex structure from tearing. In addition, there is a large clearance fit between the limiting ring 13 and the limiting mounting plate 11, and the clearance is taken as 0.2 - 0.3 mm. When the motor transmission shaft 3 drives the limiting ring 13 to rotate through the flat key 17, there will be no mutual contact and friction between the limiting ring 13 and the limiting mounting plate 11. The large clearance fit allows a certain assembly error to occur during the installation of the motor transmission shaft 3, and allows a certain offset in the position of the motor transmission shaft 3 when it is subjected to torque, ensuring that the limiting ring 13 and the limiting mounting plate 11 will not be stuck.

[0037] Furthermore, both the limiting mounting plate 11 and the limiting ring 13 are made of corrosion-resistant materials with high hardness and strength, such as 17-4PH stainless steel, TC4 titanium alloy or Stellite alloy; the remaining components are all made of corrosion-resistant materials.

[0038] Furthermore, a pair of first bearings 6 are installed on both sides of the shaft ring of the trapezoidal screw 7. Preferably, angular contact ball bearings are used and are installed face to face to enhance the axial load-bearing capacity and improve the positioning accuracy of the sub-gear 5. The limiting mounting plate 11 is pressed on the outer ring of the first bearing 6 through four positioning bolts 16 to position the first bearing 6 and apply a pre-pressure at the same time; by adjusting the installation torque of the positioning bolts 16, the magnitude of the installation pre-pressure of the first bearing 6 can be adjusted. The motor transmission shaft 3 is positioned by the second bearing 12 installed on the limiting mounting plate 11.

[0039] Furthermore, two threaded holes and two threaded clearance holes are opened on the upper edge of the limiting mounting plate 11. The threaded holes are matched with the threaded bottom holes on the valve body 15 and are connected through the positioning bolts 16, which can ensure its positioning accuracy and meet the assembly error; the threaded clearance holes adopt a tight threaded clearance and are connected to the threaded bottom holes of the valve body through bolts, mainly playing the role of bearing the motor locked-rotor torque; the threaded clearance ensures that interference and jamming are not likely to occur during assembly.

[0040] The installation assembly includes a motor mounting plate 2, a gear group outer cover 4 and a plug 14. The gear group outer cover 4 is installed outside the sub-gear 5 and the main gear 9 and is fixed on the valve body 15; the torque motor 1 is installed on the gear group outer cover 4 through the motor mounting plate 2. The trapezoidal screw 7 and the trapezoidal nut 8 are both installed in the plug 14, and the plug 14 guides the trapezoidal nut 8.

[0041] Furthermore, the inside of the gear set is filled with hydraulic lubricating oil to ensure sufficient lubrication when relative movement occurs between the first bearing 6, the second bearing 12, the main gear 9 and the pinion gear 5 gear pair, and the trapezoidal screw 7 and the trapezoidal nut 8 screw pair, reduce the friction coefficient, reduce the torque required for the movement of each rotating pair, thereby reducing the required power of the torque motor 1, and effectively saving the energy of the submersible.

[0042] Furthermore, the torque motor, the inside of the control mechanism, and the control valve group all adopt independent pressure compensation. A compensation pipe joint is provided on the outer cover 4 of the gear set, and a pressure compensation pipe leading into the inside of the outer cover 4 of the gear set is connected to this compensation pipe joint; when the valve group is in a high-pressure marine environment, the external high-pressure seawater squeezes the pressure compensation hose, causing the pressure compensation hose to deform and transmitting the marine pressure to the inside of the outer cover 3 of the gear set, so that the pressure inside the outer cover of the gear set is consistent with the external marine environment. The pressure compensation pipe of the torque motor 1 is integrated with its control cable, and the cable also provides a pressure compensation function. The valve body 15 is equipped with a pressure compensation pipe in the spring chamber at its lower end. The torque motor 1 is isolated from the gear set through the internal mechanical seal to prevent the seawater infiltrated into the gear set from entering the motor interior and damaging the motor. The gear set cavity and the valve body 15 are isolated by the sealing rings on the push rods of the respective stop valves. Pressure compensation is achieved by connecting a hose through a pressure compensation joint and filling it with oil inside, which not only meets the lubrication requirements but also performs pressure compensation to achieve internal and external pressure balance.

[0043] The embodiment of the present invention also provides an integrated valve group, which includes the above-mentioned electric actuator and control valve group; there are four pinion gears 5 in the electric actuator, and correspondingly four trapezoidal screws 7 and four trapezoidal nuts 8. The control valve group includes four stop valves A, B, C, D and a balance valve. The balance valve is arranged between the seawater pump and the stop valves. Specifically, the inlet of the balance valve is connected to the outlet of the seawater pump, and the outlet of the balance valve is connected to two adjacent stop valves (i.e., connected to B and D, or connected to A and C). The four stop valves are evenly distributed around the central axis of the torque motor 1 and form a bridge circuit around the torque. The stop valves A, B, D, C are connected end to end in sequence through the flow channels of the valve group; the ends of the four stop valves are respectively connected to a trapezoidal screw and a trapezoidal nut through plugs. The trapezoidal screw rotates to drive the axial movement of the trapezoidal nut to output axial force, pushing the stop valve push rod to control the opening and closing of the stop valve. The stop valve A and the stop valve D are placed opposite to each other, and the stop valve B and the stop valve C are placed opposite to each other; the thread helix directions of the trapezoidal screws and trapezoidal nuts corresponding to the opposite stop valves are the same, and the thread helix directions of the trapezoidal screws and trapezoidal nuts corresponding to the adjacent stop valves are opposite; realizing the opening and closing control of the four stop valves by the forward and reverse rotation of a torque motor. Since the opening degree of the stop valve spool, that is, the displacement size of the spool, is limited, there is also a certain allowable rotation range for the rotation angle of the torque motor.

[0044] During operation, when the torque motor 1 is subject to misoperation or malfunctions itself, the output angle of the motor exceeds the specified range. At this time, the limiting ring 13 comes into contact and extrusion with the limiting convex structure on the limiting mounting plate 11; the torque motor 1 transmits the torque to the limiting ring 13 through the motor transmission shaft 3, and the limiting ring 13 transmits the torque to the limiting mounting plate 11 through the contact between the limiting convex structures; the limiting mounting plate 11 transmits the torque to the valve body 15 through the 4 positioning bolt holes and 4 positioning bolts 16 on it; mechanical limitation occurs between the limiting ring 13 and the limiting mounting plate 11, and the motor transmission shaft 3 cannot rotate normally, causing the output torque of the torque motor 1 to continuously increase, thereby triggering the stall protection of the motor.

[0045] Under normal operation of the driving device, the torque input by the torque motor 1 mainly acts on the mutual extrusion between the teeth of the main gear 9 and the secondary gear 5, the trapezoidal thread transmission of the trapezoidal screw 7 and the trapezoidal nut 8, the contact between the trapezoidal nut 8 and the stop valve push rod, and the extrusion between the stop valve screw and the stop valve spool. Without a limiting protection device, when the torque motor 1 undergoes misoperation or malfunctions and causes a stall, the stall torque output by the torque motor 1 will be applied to the above-mentioned contact pairs, which may cause the trapezoidal thread between the trapezoidal screw 7 and the trapezoidal nut 8 to break, the trapezoidal screw 7 to break, and the stop valve stem to deform, resulting in the basic failure of the control valve group function and causing serious accidents. Under the protection of the mechanical limiting device, when the motor stalls, the stall torque mainly acts on the mutual contact extrusion between the limiting convex structures of the limiting ring 13 and the limiting mounting plate 11 and the extrusion between the limiting mounting plate 11 and the 4 positioning bolts 16, basically eliminating the problem of the control valve group function failure caused by the over-angle rotation of the torque motor 1.

[0046] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An electric actuator with safety limit, characterized in that: Used to realize the opening and closing control of each stop valve in the control valve group, the electric actuator includes a drive component and a limit component, among which: The driving assembly comprises a torque motor (1), a motor transmission shaft (3), a sub-gear (5), a main gear (9), a trapezoidal screw (7) and a trapezoidal nut (8); the torque motor (1) is connected to the main gear (9) via the motor transmission shaft (3), thereby driving the main gear (9) to rotate; the sub-gear (5) is meshed with the main gear (9), and the sub-gear (5) is connected to the top of the trapezoidal screw (7) via a flat key; the trapezoidal screw (7) and the corresponding trapezoidal nut (8) are connected via threads to transmit power, and the trapezoidal nut (8) is used to connect the top rod of the stop valve; The limit assembly comprises a limit mounting plate (11) and a limit ring (13); the limit mounting plate (11) is used to be mounted on the valve body of the control valve group via positioning bolts (16); the limit ring (13) is connected to the end of the motor drive shaft (3) via a flat key; there is a clearance fit between the limit ring (13) and the limit mounting plate (11), and both the inner side of the limit mounting plate (11) and the outer side of the limit ring (13) have limit protrusion structures.

2. The electric actuator with safety limit as claimed in claim 1, characterized in that: A pair of first bearings (6) are installed on both sides of the collar of the trapezoidal screw (7), and the limit mounting plate (11) is pressed on the outer ring of the first bearing (6) through a positioning bolt (16) to position the first bearing (6) and apply pre-pressure at the same time.

3. The electric actuator with safety limit as claimed in claim 2, characterized in that: The first bearing (6) is an angular contact ball bearing, and a pair of angular contact ball bearings are installed face to face.

4. The electric actuator with safety limit as claimed in claim 1, characterized in that: The limiting mounting plate (11) is provided with a second bearing (12), and the second bearing (12) is used to position the motor transmission shaft (3).

5. The electric actuator with safety limit as claimed in claim 1, characterized in that: The limiting protrusion structures on the limiting mounting plate (11) and the limiting ring (13) are both fan-shaped, and the two fan-shaped structures have the same angle and are concentric; the head and the root of the limiting protrusion structure are both rounded.

6. The electric actuator with safety limit as claimed in claim 1, characterized in that: The limiting mounting plate (11) and the limiting ring (13) are made of 17-4PH stainless steel, TC4 titanium alloy or Stellite alloy.

7. The electric actuator with safety limit according to any one of claims 1 to 6, characterized in that: The invention also comprises a mounting assembly, wherein the mounting assembly comprises a motor mounting plate (2) and a gear set outer cover (4), wherein the gear set outer cover (4) is mounted on the outside of the secondary gear (5) and the main gear (9) and is fixed on the valve body; and the torque motor (1) is mounted on the gear set outer cover (4) via the motor mounting plate (2).

8. The electric actuator with safety limit as claimed in claim 7, characterized in that: A compensation pipe joint is provided on the gear set outer cover (4), and a pressure compensation pipe which passes into the gear set outer cover (4) is connected to the compensation pipe joint.

9. The electric actuator with safety limit as claimed in claim 7, characterized in that: The installation assembly further comprises a screw plug (14), in which the trapezoidal screw rod (7) and the trapezoidal nut (8) are both installed, and the screw plug (14) guides the trapezoidal nut (8).

10. An integrated valve group, characterized in that: The electric actuator comprises a safety limit electric actuator and a control valve group as claimed in any one of claims 1 to 9; the electric actuator has four pinion gears (5), and correspondingly has four trapezoidal screws (7) and four trapezoidal nuts (8); The control valve group comprises four stop valves A, B, C, D and a balancing valve; the inlet of the balancing valve is connected to the outlet of the seawater pump, and the outlet of the balancing valve is connected to the stop valve; the four stop valves are evenly distributed around the central axis of the torque motor (1), the stop valves A, B, D, C are connected end to end in sequence to form a bridge, and each stop valve is connected to a trapezoidal nut (8); the stop valve A and the stop valve D are placed opposite to each other, and the stop valve B and the stop valve C are placed opposite to each other; the trapezoidal screws and the trapezoidal nuts corresponding to the stop valves placed opposite to each other have the same thread rotation direction, and the trapezoidal screws and the trapezoidal nuts corresponding to the stop valves placed adjacent to each other have opposite thread rotation directions.

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