Complete static seal underwater electric cylinder

Abstract

The invention discloses a complete static seal underwater electric cylinder, and belongs to the technical field of underwater actuator design. The device comprises a pressure compensator, an executing mechanism and a servo motor. The pressure compensator is installed at the tail end of the servo motor, and a rolling diaphragm is arranged in the pressure compensator and used for balancing internal and external pressure of the underwater electric cylinder. The actuating mechanism is installed at the front end of the servo motor and connected with a load, and an actuator piston rod and a rolling diaphragm are arranged in the actuating mechanism. The pressure compensator, the executing mechanism and the servo motor are coaxially arranged, and the servo motor outputs torque to drive an actuator piston rod of the executing mechanism to stretch out and draw back so as to drive a load. By means of the double-diaphragm type pressure compensation combination design, complete static sealing work of the underwater electric cylinder is achieved.

Description

TECHNICAL FIELD

[0001] The application relates to a completely static sealing underwater electric cylinder and belongs to the technical field of underwater actuator design. BACKGROUND

[0002] Underwater actuators are widely used in underwater vehicles or ocean engineering devices to realize the motion control of various mechanisms. At present, most underwater actuators adopt hydraulic actuators. Underwater electric cylinders have more and more applications due to their small size and high motion precision. Whether hydraulic actuators or underwater electric cylinders, dynamic sealing is mostly adopted, that is, the piston rod of the actuator realizes sealing with seawater through the sealing surface formed by the dynamic sealing ring mounted on the actuator shell. However, the marine organisms and various pollutants attached to the piston rod for a long time in seawater will damage the sealing ring when the piston rod moves, ultimately affecting the dynamic sealing effect, causing working oil leakage, reducing the working reliability of the underwater electric cylinder and increasing the maintenance cost. In the case that integrated underwater electric cylinders are increasingly widely used in the field of underwater linear actuation, the limited oil volume of the compensator of the integrated electromechanical actuator is affected more by the leakage of dynamic sealing, which seriously affects the application of the underwater electric cylinder in the field of underwater linear actuation.

[0003] Chinese patent CN114649902 discloses an underwater electric cylinder, which improves the sealing performance of the electric cylinder through the full sealing arrangement between the shell, the outer pipe, the power pipe guide device, the front end cover, the joint and the power pipe. It solves the sealing protection of the whole electric cylinder, and the dynamic sealing of the piston rod is still realized through the piston sealing ring, without solving the leakage problem of dynamic sealing.

[0004] Chinese patent CN109089397 discloses an underwater electric actuator, which seals the whole electric actuator through a protection barrel and adds a sealing chamber to the dynamic sealing displacement. From the outside to the inside, there are a sponge insulation oil filling area, a rubber sleeve and a viscous insulation asbestos ring coaxially arranged in sequence, a sealing chamber side opening is formed in the side wall of the sealing chamber and an isolation membrane is installed, the sliding gap between the sealing chamber and the telescopic rod is reduced through the water pressure compression sealing material mode, the sealing performance is improved and the leakage is reduced. This patent seals the whole electric actuator and enhances the dynamic sealing through the addition of the sealing chamber, but does not completely solve the leakage problem of dynamic sealing.

[0005] The Chinese patent CN118589745A discloses a completely static sealing underwater electric cylinder and an operating method. The completely static sealing underwater electric cylinder comprises a cylinder body, a motor reducer assembly is fitted in the cylinder body, and a rolling film is installed on the left end face of the cylinder body and the motor reducer assembly. The inside of the rolling film is filled with insulating oil in a sealed cavity formed by other static seals. The rolling film realizes static sealing of a push rod reciprocating linear motion pair and also plays a role of a compensator. The rotating motion of the motor and the reducer is converted into reciprocating motion through threads and guide keys on the cylinder body, which has large sliding friction and low efficiency. The guide groove is opened on the transmission thread, which can easily cause thread deformation and affect transmission reliability. When the U-shaped rolling film piece is retracted, the axial length of the electric cylinder and the film piece is too long, which affects application. SUMMARY

[0006] The technical problem solved by the present application is to overcome the shortcomings of the prior art and provide a completely static sealing underwater electric cylinder. The double diaphragm type pressure compensator combination design is adopted to realize completely static sealing operation and solve the problems of low efficiency and insufficient reliability of the existing underwater electric cylinder.

[0007] The technical solution of the present application is as follows:

[0008] A completely static sealing underwater electric cylinder comprises a pressure compensator, an actuator and a servo motor.

[0009] The pressure compensator is installed at the tail end of the servo motor and is used to balance the pressure inside and outside the underwater electric cylinder. The pressure compensator is internally provided with a rolling diaphragm, which divides the inner cavity of the pressure compensator into two cavities. The cavity adjacent to the servo motor is in communication with the inner cavity of the servo motor, and the other cavity is in communication with seawater.

[0010] The actuator is installed at the front end of the servo motor and is connected to a load. The actuator is internally provided with an actuator piston rod and a rolling diaphragm. The rolling diaphragm divides the inner cavity of the actuator into two cavities. The cavity adjacent to the servo motor is in communication with the inner cavity of the servo motor, and the other cavity is in communication with seawater.

[0011] The pressure compensator, the actuator and the servo motor are coaxially arranged. The servo motor drives the actuator piston rod of the actuator to extend and retract, thereby driving the load.

[0012] Further, the pressure compensator comprises a rolling diaphragm, a spring, a compensator end cover, a compensator shell, a diaphragm pressing plate and a compensator piston.

[0013] The compensator end cover is connected to the tail of the servo motor.

[0014] The compensator shell is installed at the end of the compensator end cover. The shell is provided with a water passing hole.

[0015] The spring, the compensation piston, the diaphragm pressing plate and the rolling diaphragm are located between the compensator end cover and the compensator shell.

[0016] The spring, the compensation piston and the diaphragm pressing plate are coaxially arranged, the spring is sleeved on the compensation piston, and the spring pre-tightening provides the initial pressure.

[0017] The sealing lip at one end of the rolling diaphragm is mounted on the compensator end cover and the compensator shell, and the sealing lip at the other end is fixed on the diaphragm pressing plate and the compensation piston; the sealing lip realizes oil-water separation by means of initial installation compression and pressure auxiliary sealing, so that two cavity bodies, i.e., an oil cavity and a water cavity, are formed in the pressure compensator; the oil cavity is communicated with the inner cavity of the servo motor through the oil passing hole in the servo motor; and the water cavity is communicated with seawater outside the compensator shell.

[0018] The compensation piston and the diaphragm pressing plate drive the rolling diaphragm to move, so that the volumes of the oil cavity and the water cavity change correspondingly.

[0019] Further, the movable volume in the pressure compensator simultaneously satisfies the total volume change amount of the maximum volume change generated when the actuator extends and retracts and the volume change of the oil in the underwater electric cylinder generated when the temperature and pressure change.

[0020] Further, when the volume of the oil in the underwater electric cylinder changes due to the temperature and pressure, the volume of the oil cavity of the pressure compensator changes accordingly, so that pressure compensation is realized.

[0021] Further, the actuator comprises the rolling diaphragm, the front end cover, the outer cylinder, the actuator piston rod and the sleeve.

[0022] The front end cover is fixed at the front end of the servo motor.

[0023] The outer cylinder is fixedly connected with the front end cover, and the outer cylinder is provided with a water passing hole.

[0024] The actuator piston rod is a lead screw and is connected with the sleeve in a matched mode.

[0025] The sealing lip at one end of the rolling diaphragm is fixed on the front end cover and the outer cylinder, and the sealing lip at the other end is mounted on the actuator piston rod and the sleeve; the sealing lip realizes oil-water separation by means of initial installation compression and pressure auxiliary sealing, so that two cavity bodies, i.e., an oil cavity and a water cavity, are formed in the actuator; the oil cavity is communicated with the inner cavity of the servo motor through the oil passing hole in the servo motor; and the water cavity is communicated with seawater outside the outer cylinder.

[0026] The actuator piston rod and the sleeve drive the rolling diaphragm to move along the inner cavity of the outer cylinder, so that the volumes of the oil cavity and the water cavity change correspondingly.

[0027] Further, when the actuator piston rod is located at the middle of the stroke, the two sealing lips of the rolling diaphragm are located in the same plane, and the length of the rolling diaphragm is only half of the stroke.

[0028] Further, the rolling diaphragm is installed on the sealing lip of the front end cover and the outer cylinder, and is arranged at the position closest to the servo motor rotor.

[0029] Further, the underwater electric cylinder adopts a reverse planetary roller screw, and the screw shaft is directly used as the actuator piston rod to directly output driving load.

[0030] Further, the servo motor adopts a screw nut and motor rotor integrated design, the inner surface of the motor rotor is provided with threads, and the threads are used as the screw nut to be connected with the actuator piston rod through the roller; the annular cavity is formed between the motor rotor and the actuator piston rod, and when the actuator piston rod is fully retracted, the rolling diaphragm can be completely embedded in the annular cavity.

[0031] Further, when the underwater electric cylinder receives an actuating instruction, the actuator piston rod and the sleeve in the actuator drive the rolling diaphragm to move, the oil cavity of the actuator changes in volume, the diaphragm pressing plate and the compensation piston in the pressure compensator drive the rolling diaphragm to move, the oil cavity of the pressure compensator changes in volume, the total volume of the underwater electric cylinder remains unchanged, and pressure compensation is realized.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] (1) The present application adopts a double-diaphragm pressure compensator combination to realize completely static sealing work of the underwater electric cylinder. One pressure compensator is pressurized by 0.02-0.05 MPa through a spring, and the rolling diaphragm has sealing lips at two ends and is fixed on the shell and the compensation piston respectively. The sealing lips realize oil-water isolation through initial installation compression and pressure auxiliary sealing, the movable volume of the compensator satisfies the total volume change amount of the maximum volume change generated when the actuator piston rod is retracted and the volume change generated when the oil in the underwater electric cylinder changes with temperature and pressure, and the rolling diaphragm in the second pressure compensator also has sealing lips at two ends and is fixed between the motor shell and the actuator piston rod. The sealing lips realize oil-water isolation through initial installation compression and pressure auxiliary sealing, and the two diaphragms and other static sealing rings realize completely static sealing and zero leakage of the underwater electric cylinder.

[0034] (2) The present application adopts a reverse planetary roller screw transmission and a screw nut and motor rotor integrated design scheme, and the screw shaft is directly output, which greatly reduces the total volume change of the underwater electric cylinder when the actuator piston rod is retracted, reduces the movable volume of the first compensator, and realizes miniaturization design of the pressure compensator.

[0035] (3) The present invention adopts a layout in which the sealing lips at both ends of the diaphragm are on the same plane when the underwater electric cylinder is in the middle of its stroke. The length of the diaphragm is only half of the stroke, thus realizing the miniaturization of the diaphragm design. Furthermore, by utilizing the annular cavity formed between the lead screw nut and the lead screw shaft by the planetary rollers, the diaphragm can be tightly attached to the cylindrical surface of the lead screw shaft through the internal compensation pressure. When the actuator piston rod retracts, it is fully embedded in the annular cavity, thus saving the axial length of the underwater electric cylinder. Attached Figure Description

[0036] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0037] Figure 1 This is a structural diagram of a fully statically sealed underwater electric cylinder according to an embodiment of the present invention;

[0038] Figure 2 This is a detailed structural diagram of the pressure compensator and actuator according to an embodiment of the present invention;

[0039] Figure 3 This is a detailed structural diagram of the servo motor according to an embodiment of the present invention;

[0040] Figure 4 The diagram shows the state of the rolling diaphragm in an embodiment of the present invention. (a) is the mid-position state, and (b) is the fully contracted state. Detailed Implementation

[0041] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be 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 disclosure to those skilled in the art.

[0042] This invention proposes a fully statically sealed underwater electric cylinder, such as... Figure 1 As shown, it includes a pressure compensator 1, an actuator 2, and a servo motor 3.

[0043] The pressure compensator 1 is located at the rear end of the underwater electric cylinder, and the actuator 2 is located at the front end of the servo motor 3. The pressure compensator 1, the actuator 2 and the servo motor 3 are arranged coaxially. The pressure compensator 1 is used to balance the internal and external pressure of the underwater electric cylinder. The actuator 2 executes commands to drive the load, and the servo motor 3 outputs torque to drive the actuator.

[0044] like Figure 2The pressure compensator 1 includes a rolling diaphragm 101, a spring 102, a compensator end cap 103, a compensator housing 104, a diaphragm pressure plate 105, and a compensating piston 106; wherein,

[0045] One end of the rolling diaphragm 101 is mounted on the compensator end cover 103 and the compensator housing 104, and the other end is fixed to the diaphragm pressure plate 105 and the compensating piston 106. The spring 102 is arranged coaxially with the compensating piston 106 and is pre-tightened to provide initial pressure.

[0046] Spring 102 provides an initial pressure of 0.02 to 0.05 MPa to pressure compensator 1. The sealing lips at both ends of the rolling diaphragm 101 achieve oil-water isolation through initial installation compression and pressure-assisted sealing. Water passage holes are machined in the compensator housing 104 to directly connect with seawater. The left chamber of pressure compensator 1 is a water chamber, and the right chamber is an oil chamber. The movable volume of pressure compensator 1 meets the total volume change of the maximum volume change generated when the actuator piston rod extends and retracts, and the volume change generated when the oil inside the underwater electric cylinder changes with temperature and pressure. The volume change is achieved by moving the rolling diaphragm 101 through the diaphragm pressure plate 105 and the compensating piston 106, thereby realizing pressure compensation.

[0047] Actuator 2 is equivalent to the second pressure compensator in the underwater electric cylinder, and includes: a rolling diaphragm 201, a front end cover 202, an outer cylinder 203, an actuator piston rod 204, and a sleeve 205; wherein,

[0048] One end of the rolling diaphragm 201 is mounted on the front end cover 202 and the outer cylinder 203, and the other end is fixed on the actuator piston rod 204 and the sleeve 205.

[0049] The sealing lips at both ends of the rolling diaphragm 201 achieve oil-water isolation through initial installation compression and pressure-assisted sealing. The outer cylinder 203 is machined with water passage holes, directly connecting to seawater. The left chamber of the actuator 2 is an oil chamber, and the right chamber is a water chamber. The oil chambers of the pressure compensator 1 and the actuator 2 are connected through the oil passage hole in the servo motor 3, realizing the overall connection of the oil chambers of the pressure compensator 1, the servo motor 3, and the actuator 2, forming a single integrated chamber. When the underwater electric cylinder receives a command to actuate, the actuator piston rod 204 and the sleeve 205 drive the rolling diaphragm 201 to move, causing a volume change in the oil chamber of the actuator 2. The diaphragm pressure plate 105 and the compensation piston 106 drive the rolling diaphragm 101 to move accordingly, causing a volume change in the oil chamber of the pressure compensator 1. The total volume of the underwater electric cylinder remains unchanged, achieving pressure compensation. When the volume of the oil inside the underwater electric cylinder changes with temperature and pressure, the volume of the oil chamber in the pressure compensator 1 changes accordingly, also achieving pressure compensation.

[0050] The rolling diaphragm 101, rolling diaphragm 201, and other oil-water isolation installation parts together with the static sealing ring achieve complete static sealing and zero leakage of the underwater electric cylinder.

[0051] like Figure 3 The underwater electric cylinder adopts a reverse planetary roller screw drive and uses an integrated design of screw nut and motor rotor. The motor rotor 301 in servo motor 3 is also a screw nut. Compared with threaded drive, it improves transmission efficiency and saves axial space of the underwater electric cylinder.

[0052] By utilizing the characteristic that the reverse planetary roller screw shaft is cylindrical except for the section that mates with the planetary rollers, the screw shaft directly outputs and drives the load as the actuator piston rod. The output shaft diameter can be optimized to the minimum, which greatly reduces the change in the total volume of the underwater electric cylinder when the actuator piston rod 204 extends and retracts, reduces the active volume of the first compensator, and realizes the miniaturization design of the pressure compensator.

[0053] like Figure 4 In diagram (a), the underwater electric cylinder is in the middle of its stroke. When this position is achieved, the static sealing lips of the rolling diaphragm 201 are on the same plane, and the length of the rolling diaphragm 201 is only half of its stroke. This reduces the processing difficulty of the rolling diaphragm 201 and improves its operational reliability. Furthermore, the lip of the fixed end of the rolling diaphragm 201 is positioned closest to the lead screw nut. Utilizing the annular cavity formed between the lead screw nut and the lead screw shaft by the planetary rollers, the internal compensating pressure allows the rolling diaphragm 201 to tightly adhere to the cylindrical surface of the lead screw shaft. Figure 4 In the fully retracted state (b), the rolling diaphragm 201 can be fully embedded in the annular cavity before the lead screw nut and lead screw shaft when the actuator piston rod 204 retracts, thus optimizing the axial length of the underwater electric cylinder.

[0054] The embodiments described above are merely preferred embodiments of the present invention. Ordinary variations and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A fully statically sealed underwater electric cylinder, characterized in that, Includes pressure compensators, actuators, and servo motors; The pressure compensator is installed at the tail end of the servo motor to balance the internal and external pressures of the underwater electric cylinder. The pressure compensator is equipped with a rolling diaphragm, which divides the inner cavity of the pressure compensator into two chambers. The chamber adjacent to the servo motor is connected to the inner cavity of the servo motor, and the other chamber is connected to seawater. The actuator is installed at the front end of the servo motor and connected to the load; the actuator has an actuator piston rod and a rolling diaphragm inside; the rolling diaphragm divides the inner cavity of the actuator into two chambers, the chamber adjacent to the servo motor is connected to the inner cavity of the servo motor, and the other chamber is connected to seawater; The pressure compensator, actuator, and servo motor are arranged coaxially. The servo motor outputs torque to drive the actuator piston rod of the actuator to extend and retract, thereby driving the load.

2. The fully statically sealed underwater electric cylinder according to claim 1, characterized in that, The pressure compensator includes a rolling diaphragm, a spring, a compensator end cap, a compensator housing, a diaphragm pressure plate, and a compensating piston; The compensator end cap is connected to the tail of the servo motor; The compensator housing is installed at the end of the compensator end cover, and the housing is provided with a water passage hole; The spring, compensating piston, diaphragm pressure plate and rolling diaphragm are located between the compensator end cap and the compensator housing; The spring, the compensating piston, and the diaphragm plate are arranged coaxially, with the spring fitted on the compensating piston and the spring preload providing initial pressure. The sealing lip at one end of the rolling diaphragm is installed on the compensator end cover and compensator housing, while the sealing lip at the other end is fixed to the diaphragm pressure plate and compensating piston. The sealing lip utilizes initial installation compression and pressure-assisted sealing to achieve oil-water isolation, forming two cavities inside the pressure compensator: an oil cavity and a water cavity. The oil cavity is connected to the inner cavity of the servo motor through an oil passage in the servo motor; the water cavity is connected to seawater outside the compensator housing. The compensating piston and diaphragm pressure plate drive the rolling diaphragm to move, causing the oil chamber and water chamber volumes to change accordingly.

3. A fully statically sealed underwater electric cylinder according to claim 2, characterized in that, The active volume within the pressure compensator simultaneously accommodates the total volume change, including the maximum volume change during the extension and retraction of the actuator and the volume change of the oil inside the underwater electric cylinder as temperature and pressure change.

4. A fully statically sealed underwater electric cylinder according to claim 2, characterized in that, When the volume of the oil inside the underwater electric cylinder changes with temperature and pressure, the volume of the oil chamber of the pressure compensator changes accordingly, thus achieving pressure compensation.

5. A fully statically sealed underwater electric cylinder according to claim 1, characterized in that, The actuator includes a rolling diaphragm, a front cover, an outer cylinder, an actuator piston rod, and a sleeve; The front cover is fixed to the front end of the servo motor; The outer cylinder is fixedly connected to the front end cover, and the outer cylinder is provided with a water passage hole; The actuator piston rod is a lead screw shaft, which is connected to the sleeve. The sealing lip at one end of the rolling diaphragm is fixed to the front end cover and the outer cylinder, while the sealing lip at the other end is installed on the actuator piston rod and the sleeve. The sealing lip achieves oil-water isolation by using initial installation compression and pressure-assisted sealing, thus forming two cavities, an oil cavity and a water cavity, inside the actuator. The oil cavity is connected to the inner cavity of the servo motor through an oil passage in the servo motor; the water cavity is connected to seawater outside the outer cylinder. The actuator piston rod and sleeve drive the rolling diaphragm to move along the inner cavity of the outer cylinder, causing the oil chamber and water chamber volumes to change accordingly.

6. A fully statically sealed underwater electric cylinder according to claim 5, characterized in that, When the actuator piston rod is in the middle of its stroke, the two sealing lips of the rolling diaphragm are on the same plane, and the length of the rolling diaphragm is only half of the stroke.

7. A fully statically sealed underwater electric cylinder according to claim 5, characterized in that, The rolling diaphragm is installed on the sealing lip of the front cover and the outer cylinder, and is positioned as close as possible to the servo motor rotor.

8. A fully statically sealed underwater electric cylinder according to claim 5, characterized in that, The underwater electric cylinder uses a reverse planetary roller screw, with the screw shaft serving as the actuator piston rod, directly driving the load.

9. A fully statically sealed underwater electric cylinder according to claim 5, characterized in that, The servo motor adopts an integrated design of lead screw nut and motor rotor. The inner surface of the motor rotor is threaded, which acts as lead screw nut and is connected to the actuator piston rod by rollers using threads. An annular cavity is formed between the motor rotor and the actuator piston rod. When the actuator piston rod is fully retracted, the rolling diaphragm can be completely embedded in the annular cavity.

10. A fully statically sealed underwater electric cylinder according to claim 5, characterized in that, When the underwater electric cylinder receives a command to operate, the actuator piston rod and sleeve in the actuator drive the rolling diaphragm to move, causing a change in the volume of the oil chamber of the actuator. The diaphragm pressure plate and compensation piston in the pressure compensator drive the rolling diaphragm to move accordingly, and the volume of the oil chamber of the pressure compensator changes accordingly. The total volume of the underwater electric cylinder remains unchanged, thus achieving pressure compensation.

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