Multi-stage damped hydraulic cylinder and control method for wave energy power generation device

Abstract

The present invention discloses a multi-stage buffer hydraulic cylinder and control method for wave energy power generation device, which relates to the technical field of hydraulic actuators. A built-in fixed rod is installed inside the hydraulic cylinder barrel and fitted into the piston rod, and the fixed rod and piston rod cavity are used as the high-pressure working cavity, which not only reduces the effective working area but also makes the diameter of the piston rod larger, ensuring that the hydraulic cylinder can be started even in small waves, and meeting the requirements of pressure-bearing stability under the condition of pressure work. In addition, a buffer spring is installed on the front end cap and rear end cap of the hydraulic cylinder to buffer the collision caused by the piston rod's stroke being too large in the limit wave state, and the stiffness of the spring can be appropriately set to buffer the hydraulic cylinder in the case of large waves, and prevent the primary piston from colliding with the front end cap and rear end cap. The present invention greatly improves the service life and safety of the hydraulic cylinder.

Description

[Technical field]

[0001] The present invention relates to the technical field of hydraulic wave energy power generation and to the technical field of fluid pressure actuators, in particular to a multi-stage damped hydraulic cylinder and control method for a wave energy power generation device. [Background technology]

[0002] Wave energy is a clean and non-polluting marine renewable energy, with the advantages of abundant reserves and high energy density, and the research and development of wave energy utilization technology is being actively carried out in coastal countries around the world. Waves have characteristics such as round trip, low frequency and large output, and the hydraulic system with energy storage stage can effectively buffer the collision caused by these characteristics of waves, stabilize the final energy output, and meet the requirements of grid connection. For this reason, the hydraulic energy conversion system has become the mainstream choice of energy conversion methods in current wave energy devices.

[0003] In hydraulic wave energy conversion systems, hydraulic cylinders are power components that convert wave energy into hydraulic energy, but the use of conventional hydraulic cylinders is the opposite, mainly used as actuators that convert mechanical energy into hydraulic energy, and the hydraulic cylinders of wave energy devices operate in seawater (or sea steam) for a long time, and are therefore prone to failure in wave energy power generation devices due to their poor operating environment. At present, there are mainly two types of work methods in hydraulic cylinder wave energy devices. Take the point absorption type work by two floats as an example, as shown in Figure 1, the wave absorbing floats receive wave force and move upward relative to the main body to do work, but the downward movement is mainly due to the gravity of the wave absorbing float itself, and generally work is done only by wave force, that is, the energy generated by the floats moving upward to do work is utilized.

[0004] In one work method, the hydraulic cylinder is installed under the wave absorbing float and placed in seawater, one end of the hydraulic cylinder is connected to the wave absorbing float, and the other end is connected to the lower position of the main body. As shown in Figure 1, when the wave absorbing float moves upward due to the action of the waves, the rod of the hydraulic cylinder is driven to pull upward by the wave absorbing float, and the rod cavity of the hydraulic cylinder is filled with high pressure hydraulic oil, which is the work by pulling the cylinder. In this work method, the effective work area of ​​the hydraulic cylinder is S1-S2, where S1 is the area of ​​the piston, S2 is the area of ​​the piston rod, and the output is F=p×(S1-S2), where p is the pressure of the accumulator. The advantage of pulling work is that the hydraulic cylinder works in a pulled state for a long time, there is no problem of pressure-bearing stability (which only occurs when the hydraulic rod is under pressure), and the piston rod of the hydraulic cylinder is not easily damaged mechanically. However, it has more disadvantages, which are difficult to solve at present, and the main disadvantages are as follows: (1) The hydraulic cylinder is installed underwater, and the corrosion problem of the piston rod is serious. (2) The pollution problem is also serious, and a large amount of marine organisms adhere to the surface of the piston rod, and the piston rod moves frequently, so the sealing ring of the hydraulic cylinder is very easy to damage. (3) The hydraulic cylinder is installed underwater, and daily maintenance and repair are very inconvenient. (4) If the sealing ring of the hydraulic cylinder is damaged, all the hydraulic oil will leak into the seawater, which will have a great impact on the environment. (5) If the sealing ring of the hydraulic cylinder is damaged, the seawater will enter the entire hydraulic system, which will cause serious damage to the system. (6) In the case of large waves, there is a stroke limit problem, that is, if the movement range of the piston rod exceeds the stroke limit of the hydraulic cylinder, the hydraulic cylinder will collide with the hydraulic cylinder barrel, causing damage. Due to these six shortcomings, it is difficult to utilize the work of the hydraulic cylinder of the wave energy device in the pulling form on a large scale at present.

[0005] Another work method is that the hydraulic cylinder is installed above the float and installed on the sea surface, as shown in Figure 2, the float moves upward to do work, one end is connected to the wave absorbing float and the other end is connected to the top of the body, when the float moves upward, the hydraulic cylinder is pressured to do work, the rodless cavity of the hydraulic cylinder is filled with hydraulic oil, this is work by pressure on the cylinder, in this type of work method, the effective work area of ​​the hydraulic cylinder, that is, the cross-sectional area of ​​the piston is S1, the output is F=p×S1, for the same wave force and accumulator pressure, the hydraulic cylinder needs to be thinner, otherwise the hydraulic cylinder cannot be driven to move with the same wave force. This type of work method improves the disadvantages (2), (3), (4), and (5) of the work form by pulling, so currently most hydraulic cylinders use this type. In addition, other problems also arise in the work by pressure, mainly as follows: (1) It is relatively difficult to design the diameter of the piston rod of the hydraulic cylinder. If the piston rod is too thin, the hydraulic cylinder has low pressure stability (pressure stability is related to the diameter of the piston rod), the rod is easy to bend, and it leads to failure. If the piston rod is too thick, the working area is large, and the hydraulic cylinder cannot be driven to do work in small waves, and the work efficiency is low. (2) The hydraulic cylinder is installed in the sea steam, and the corrosion of the rod surface is also severe, and the sealing ring is easily damaged due to corrosion, and the pressure of the hydraulic cylinder is reduced. (3) Whether the work is done by pulling or by pressure, there is a problem regarding the stroke limit, which is how to buffer the hydraulic cylinder at the stroke limit to prevent the movement of the hydraulic cylinder from exceeding the stroke limit. Therefore, in order to make the hydraulic cylinder of the wave energy device work stably and reliably, it is important to provide a suitable hydraulic cylinder design method that can effectively solve the above problems. Summary of the Invention [Problem to be solved by the invention]

[0006] In response to the shortcomings of the prior art, the present invention provides a multi-stage buffer hydraulic cylinder and a control method for a wave energy power generation device, which installs a hollow rod inside the transmission hydraulic cylinder to greatly reduce the possibility of oil leakage during the operation of the hydraulic cylinder, solves the problem of the pressure-bearing stability of the hydraulic cylinder when working with pressure, and improves the reliability and stability of the wave energy hydraulic cylinder. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention uses the following technical means.

[0008] A multi-stage buffer hydraulic cylinder for a wave energy power generation device, which is connected to a wave energy power generation device including a body and a wave absorbing float, comprises: a cylinder barrel having a rear end cap and a front end cap at each end and connected to the body; a built-in fixed rod that is coaxially disposed within the cylinder barrel, has a hollow cavity, and extends to a front end cap at a right end thereof, and has a secondary piston attached to the right end thereof; A piston rod is coaxially fitted into the built-in fixed rod, has a hollow cavity, has a primary piston attached to its left end, and is connected to the wave absorbing float at its right end, and constitutes a multi-stage cylinder together with the cylinder barrel and the built-in fixed rod; a hollow cavity of the built-in fixed rod is a fixed rod cavity, a left end of the fixed rod cavity is connected to a primary port, a cavity surrounded by an outer wall of the built-in fixed rod, an inner wall of the piston rod, the primary piston, and the secondary piston is a sealed cavity, a portion of the hollow cavity of the piston rod other than the sealed cavity is a piston rod cavity, a cavity surrounded by an inner wall of the cylinder barrel, the rear end cap, the outer wall of the built-in fixed rod, and the primary piston is a main cavity, the main cavity is connected to a rear port, a cavity surrounded by an inner wall of the cylinder barrel, the front end cap, the outer wall of the piston rod, and the primary piston is a main rod cavity, the main rod cavity is connected to a front port, and the fixed rod cavity is connected to the piston rod cavity, The main body and the wave absorbing float move relative to each other due to the action of waves, whereby the piston rod is driven to reciprocate within the cylinder barrel.

[0009] The multi-stage buffered hydraulic cylinder for a wave energy power generation device as described above further includes an oil tank and an accumulator, the primary port sucks oil from the oil tank through a pipe equipped with a first check valve and pumps hydraulic oil to the accumulator through a pipe equipped with a second check valve, and the rear port and the front port are connected to the oil tank.

[0010] In the multi-stage buffer hydraulic cylinder for a wave energy power generation device as described above, a front buffer spring is further attached to the inner wall adjacent to the front end cap, and a rear buffer spring is further attached to the inner wall adjacent to the rear end cap.

[0011] In the above-mentioned multi-stage buffer hydraulic cylinder for wave energy power generation device, a first sealing ring is further installed between the piston rod and the front end cap, a second sealing ring is installed between the primary piston and an inner wall of the cylinder barrel, a third sealing ring is installed between an outer wall of the built-in fixed rod and the primary piston, and a fourth sealing ring is installed between the secondary piston and an inner wall of the piston rod.

[0012] In the above-mentioned multi-stage buffer hydraulic cylinder for a wave energy power generation device, the sealed cavity is further filled with an inert gas.

[0013] The multi-stage buffered hydraulic control method using the multi-stage buffered hydraulic cylinder for the wave energy power generation device as described above includes the following steps: a first control mode used when the wave absorbing float moves upward relative to the main body; a second control mode used when the wave absorbing float moves downward relative to the main body; A third control mode used in a limit wave state of the first control mode; and a fourth control mode used in a limit wave state of the second control mode.

[0014] In the above-mentioned multi-stage buffer hydraulic control method, the first control mode further comprises: When the wave absorbing float moves upward relative to the main body due to the movement of waves, the piston rod of the hydraulic cylinder also moves upward at the same time, and the main rod cavity of the hydraulic cylinder draws oil from the oil tank through the front port, and the main cavity of the hydraulic cylinder discharges hydraulic oil to the oil tank through the rear port; and when the piston rod cavity and the fixed rod cavity are filled with hydraulic oil, the hydraulic oil in the piston rod cavity and the fixed rod cavity is squeezed out and pumped to the accumulator group through the primary port and the second check valve, energy is stored, and the pressure is stabilized to generate electricity. During this process, the gas in the sealed cavity expands.

[0015] In the above multi-stage buffer hydraulic control method, the second control mode further comprises: When the wave absorbing float moves downward relative to the main body due to the action of waves, the piston rod of the hydraulic cylinder also moves downward at the same time, and the main rod cavity of the hydraulic cylinder discharges hydraulic oil into the oil tank through the front port, and the main cavity of the hydraulic cylinder draws oil from the oil tank through the rear port; and when the piston rod moves downward, the piston rod cavity and the fixed rod cavity draw oil from the oil tank through the primary port and the first check valve, and during this process, the gas in the sealed cavity is compressed.

[0016] In the above multi-stage buffer hydraulic control method, the third control mode further comprises: In the case of critical waves, when the wave absorbing float moves upward relative to the body, the piston rod also moves upward at the same time. When the primary piston moves to a certain distance from the rear end cap, the primary piston begins to compress the rear buffer spring. In the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated. The main cavity sucks in the hydraulic oil through the rear port and discharges it into the oil tank, and the heat is removed by the flow of the hydraulic oil.

[0017] In the above multi-stage buffer hydraulic control method, the fourth control mode further comprises: In the case of critical waves, when the wave absorbing float moves downward relative to the body, the piston rod also moves downward at the same time. When the primary piston moves to a certain distance from the front end cap, the primary piston begins to compress the front buffer spring. In the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated. The main rod cavity sucks in the hydraulic oil through the front port and discharges it into the oil tank, and the heat is removed by the flow of the hydraulic oil. Effect of the Invention

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. When this hydraulic cylinder is used as a power conversion member of a wave energy device, the hydraulic oil in the high pressure part mainly flows through the fixed rod cavity and the piston rod cavity, and the fourth sealing ring between the secondary piston and the piston rod plays the role of sealing. The sealing ring is generally arranged on the inner wall of the piston rod and is isolated from the outside through the sealing cavity, so that the sealing ring is effectively protected and the sealing performance of the hydraulic cylinder is improved.

[0020] 2. This hydraulic cylinder solves the problem of piston rod diameter design when work is performed by pressure, and the effective work area of ​​the hydraulic cylinder of the present invention is the cross-sectional area of ​​the piston rod cavity, which is equal to the cross-sectional area of ​​the piston rod minus the cross-sectional area of ​​the piston rod wall, so that the thickness of the piston rod can be increased to increase the diameter of the piston rod without increasing the effective work area of ​​the hydraulic cylinder. By increasing the diameter of the piston rod, the pressure-bearing stability of the piston rod of the hydraulic cylinder can be effectively improved when work is performed by pressure.

[0021] 3. In this hydraulic cylinder, buffer springs are installed on the front and rear end caps, which can buffer the movement of the piston rod of the hydraulic cylinder in the event of large waves and prevent the piston rod from exceeding the limit of its movement stroke, effectively avoiding the primary piston from colliding with the front and rear end caps and damaging the hydraulic cylinder. The heat energy generated by the compression of the springs is cooled and discharged by the hydraulic oil flowing through the front and rear ports. [Brief description of the drawings]

[0022] In order to more clearly describe the technical means in the embodiments of the present invention, the drawings necessary for the embodiments will be briefly described below. However, it is obvious that the drawings described below are merely some embodiments of the present application, and a person skilled in the art can derive other drawings based on these drawings without any creative effort.

[0023] [Figure 1] FIG. 13 is a diagram showing the installation of the hydraulic cylinders of the point absorbing wave energy device during work by pulling. [Diagram 2] FIG. 13 is a diagram showing the installation of a hydraulic cylinder of a point absorbing wave energy device when working with pressure. [Diagram 3] FIG. 1 is a schematic diagram of a multi-stage damped hydraulic cylinder for a wave energy power generation device. [Figure 4] FIG. 2 is a schematic diagram of the upward movement of the piston rod of a multi-stage damped hydraulic cylinder for a wave energy power generator; [Diagram 5] FIG. 2 is a schematic diagram of a multi-stage buffer hydraulic cylinder for a wave energy power generation device when the piston rod compresses the buffer spring upwards. [Figure 6] FIG. 2 is a schematic diagram of a downward movement of the piston rod of a multi-stage damped hydraulic cylinder for a wave energy power generator. [Figure 7] FIG. 2 is a schematic diagram of a multi-stage buffer hydraulic cylinder for a wave energy power generation device when the piston rod compresses the buffer spring downwards; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, the technical means in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, but it is obvious that the described embodiments are only some of the embodiments of the present application, and are not all of the embodiments. Based on the embodiments of the present application, all other embodiments that a person skilled in the art can obtain without creative labor are all included in the scope of protection of the present application.

[0025] (Example) In addition, the terms "first", "second", and the like in the present specification, claims, and drawings are used to distinguish between similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that the data used in this manner can be exchanged where appropriate so that the embodiments of the present invention described herein can be performed in an order other than that shown or described herein. In addition, the terms "comprise" and "have" and any variations thereof in the embodiments of the present invention are intended to cover a non-exclusive inclusion, for example, a process, method, system, product, or apparatus that includes a series of steps or units is not necessarily limited to the steps or units explicitly recited, and may include processes, methods, products, or apparatus that are not explicitly recited, or other steps or units inherent to these processes, methods, products, or apparatus.

[0026] In addition, the orientations or positional relationships indicated by terms such as "center," "longitudinal," "lateral," "length," "width," "thickness," "up," "down," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like, are based on the orientations or positional relationships shown in the drawings, and are merely intended to facilitate and simplify the description of the present invention, and are not intended to indicate or suggest that the devices or elements referred to have a specific orientation and must be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0027] In the description of the present invention, unless otherwise clearly and specifically limited, "plurality" means at least two, for example, two, three, etc. Furthermore, unless otherwise clearly specified and limited, the terms "attached", "coupled", and "connected" should be understood in a broad sense, for example, a fixed connection, a removable connection, an integral connection, a mechanical connection, an electrical connection, a direct connection, an indirect connection via an intermediate medium, or an internal communication between two elements. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific situation.

[0028] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature means that the first feature may be in direct contact with the second feature, or that the first feature and the second feature may be in indirect contact with each other via an intermediate medium. Furthermore, a first feature being "above," "above," and "on the upper surface" of a second feature means that the first feature may be directly above or diagonally above the second feature, and only means that the horizontal height of the first feature is higher than that of the second feature. A first feature being "below," "below," and "below" a second feature means that the first feature may be directly below or diagonally below the second feature, and only means that the horizontal height of the first feature is smaller than that of the second feature.

[0029] In the present invention, a built-in fixed rod is installed inside the hydraulic cylinder barrel and fitted into the piston rod, and the fixed rod and the piston rod cavity are used as the high-pressure working cavity, which not only reduces the effective working area but also makes the diameter of the piston rod larger, ensuring that the hydraulic cylinder can be started even in small waves, and meeting the requirements of pressure-bearing stability under the condition of work by pressure. The front and rear end caps of the hydraulic cylinder are equipped with buffer springs to buffer the collision caused by the piston rod's stroke being too large in the limit wave state, and the spring stiffness can be appropriately set to buffer the hydraulic cylinder in the case of large waves, so that the primary piston does not collide with the front and rear end caps. In addition, four sealing rings are installed in the hydraulic cylinder, which largely solves the problem of the sealing ring damage of the high-pressure working cavity.

[0030] Referring to FIG. 3, FIG. 3 shows a schematic configuration diagram of a multi-stage buffered hydraulic cylinder for a wave energy power generation device, the multi-stage buffered hydraulic cylinder includes a cylinder barrel 1, a rear end cap 2 is provided at the rear of the cylinder barrel, the rear end cap 2 and the cylinder barrel 1 can be connected by a bolt, so that it is easy to remove and install, and a primary port 3 is provided on the rear end cap 2. The primary port 3 communicates with a first check valve 6 and a second check valve 7, and can suck oil from the oil tank through the first check valve 6, and pump the oil in the hydraulic cylinder to the accumulator through the second check valve 7, so as to realize the conversion from mechanical energy to hydraulic energy. A rear port 4 and a front port 5 are provided on the cylinder barrel 1 of the hydraulic cylinder, and the rear port 4 and the front port 5 are directly connected to the oil tank. A front end cap 8 is provided on the cylinder barrel 1 of the hydraulic cylinder, and the front end cap 8 and the cylinder barrel 1 are connected by a bolt, so that it is easy to remove and install.

[0031] Furthermore, a hollow piston rod 9 is installed in the cylinder barrel 1 of the hydraulic cylinder, a primary piston 10 is attached to the left end of the piston rod 9, the primary piston 10 engages with the inner wall of the cylinder barrel 1, and a second sealing ring 21 is installed between them, so that the piston rod 9 can reciprocate along the cylinder barrel. A first sealing ring 20 is installed between the piston rod 9 and the front end cap 8, and a main rod cavity 15 is surrounded by the piston rod 9, the primary piston 10, the inner wall of the cylinder barrel 1, and the front end cap 8, so that the low-pressure hydraulic oil in the main rod cavity 15 is sucked in and discharged through the rear port 4.

[0032] Furthermore, a front buffer spring 13 is attached to the inner wall of the front end cap 8 to buffer the piston rod 9 in rough seas and prevent the motion stroke of the piston rod 9 from exceeding the front limit position. A rear buffer spring 14 is also attached to the inner wall of the rear end cap 2 to buffer the piston rod 9 in rough seas and prevent the motion stroke of the piston rod 9 from exceeding the rear limit position.

[0033] Furthermore, an internal fixed rod 11 is installed on the inner wall of the rear end cap 2, the outer wall of the internal fixed rod 11 engages with the primary piston 10, and a third sealing ring 22 is installed between them. The internal fixed rod 11 is a hollow circular rod, and a fixed rod cavity 18 is installed inside. The length of the internal fixed rod 11 extends to the edge of the front end cap 8, and a secondary piston 12 is installed on the front end of the internal fixed rod 11, the secondary piston 12 engages with the inner wall surface of the piston rod 9, and a fourth sealing ring 23 is installed between them. The secondary piston 12 divides the hollow cavity of the piston rod 9 into two parts, namely, a piston rod cavity 17 and a sealing cavity 19.

[0034] Furthermore, since the rear end of the built-in fixed rod 11 is connected to the primary port 3, the hydraulic oil in the fixed rod cavity 18 can flow in and out from the rear end primary port 3. When the fixed rod cavity 18 of the built-in fixed rod 11 is connected to the piston rod cavity 17 and the hydraulic cylinder works, the high pressure part of the hydraulic oil mainly flows through the fixed rod cavity 18 and the piston rod cavity 17.

[0035] Additionally, the sealing cavity 19 may be filled with nitrogen gas or other inert gas at an appropriate pressure to protect the fourth sealing ring 23 .

[0036] Referring to Figs. 4 to 7, Figs. 4 to 7 show the motion process of the multi-stage buffer hydraulic cylinder in different wave cases.

[0037] The piston rod 9 of the hydraulic cylinder is connected to the wave absorbing float of the wave energy power generation device, and the cylinder barrel 1 of the hydraulic cylinder is connected to the main body of the wave energy power generation device, and the wave absorbing float and the main body move relative to each other due to the action of waves, driving the piston rod 9 to reciprocate within the cylinder barrel 1.

[0038] In normal wave conditions, when the wave energy device is driven by the waves and the wave absorbing float moves upward relative to the body, the piston rod 9 of the hydraulic cylinder also moves upward at the same time, as shown in Figure 4. The main rod cavity 15 of the hydraulic cylinder draws oil from the oil tank through the front port 5, and the main cavity 16 of the hydraulic cylinder discharges hydraulic oil to the oil tank through the rear port 4. The piston rod 9 is a circular rod with a hollow interior, and the piston rod cavity 17 is filled with hydraulic oil. A built-in fixed rod 11 is welded to the rear end cap 2 of the cylinder barrel 1, and the front end of the fixed rod cavity 18 of the built-in fixed rod 11 communicates with the piston rod cavity 17, and the rear cavity of the built-in fixed rod 11 communicates with the primary port 3, and when actuated, the fixed rod cavity 18 is also filled with hydraulic oil. When the piston rod 9 moves upward, the hydraulic oil in the piston rod cavity 17 and the fixed rod cavity 18 is squeezed out and pumped to the accumulator group through the primary port 3 and the second check valve, storing energy, stabilizing the pressure and generating electricity. During this process, the gas in the sealed cavity 19 expands. According to the design, under normal wave conditions, when the piston rod 9 moves upward, it usually does not move to the position of the rear buffer spring 14.

[0039] In normal wave conditions, when the wave energy device is driven by the waves and the wave absorbing float moves downward relative to the body, the piston rod 9 of the hydraulic cylinder also moves downward at the same time, as shown in FIG. 6. The main rod cavity 15 of the hydraulic cylinder discharges hydraulic oil to the oil tank through the front port 5, and the main cavity 16 of the hydraulic cylinder sucks oil from the oil tank through the rear port 4. When the piston rod 9 moves downward, the piston rod cavity 17 and the fixed rod cavity 18 suck oil from the oil tank through the primary port 3 and the first check valve. In this process, the gas in the sealed cavity 19 is compressed. According to the design, in normal wave conditions, when the piston rod 9 moves downward, it usually does not move to the position of the front buffer spring 13.

[0040] In the state of the limit wave, when the wave energy device is driven by the wave and the wave absorbing float moves upward relative to the body, the piston rod 9 also moves upward at the same time, as shown in Figure 5. However, unlike the normal wave state, the primary piston 10 at the left end of the piston rod 9 is driven by the limit big wave, and the wave absorbing float is subjected to a very large wave force, so that the primary piston 10 often collides with the rear end cap 2 of the hydraulic cylinder, and if no measures are taken, the hydraulic cylinder may be damaged by the collision. In order to buffer the damage caused by the collision, a rear buffer spring 14 is installed on the rear end cap 2, and when the primary piston 10 moves to a certain distance from the rear end cap 2, the primary piston 10 begins to compress the rear buffer spring 14, and the rigidity of the rear buffer spring 14 is set according to the magnitude of the limit wave force, ensuring that the primary piston 10 does not collide with the rear end cap even under the action of the limit wave. During the entire process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated. In order to remove the heat generated during the buffering process, the main cavity 16 draws in hydraulic oil through the rear port 4 and discharges it into the low-pressure oil tank, so that the heat is removed by the flow of hydraulic oil.

[0041] In the limit wave state, when the wave energy device is driven by the waves and the wave absorbing float moves downward relative to the body, the piston rod 9 also moves downward at the same time, as shown in Figure 7, and similarly, the primary piston 10 often collides with the front end cap 8 of the hydraulic cylinder due to the limit large wave. In order to buffer the downward movement width of the primary piston 10, a front buffer spring 13 is also attached to the front end cap 8 of the hydraulic cylinder, and when the primary piston 10 moves to a certain distance from the front end cap 8, the primary piston 10 begins to compress the front buffer spring 13, and the stiffness of the front buffer spring 13 is set according to the magnitude of the limit wave force. In order to cool the thermal energy generated during the spring buffering and compression process, the main rod cavity 15 sucks hydraulic oil through the front port 5 and discharges it into the low-pressure oil tank, and the heat is removed by the flow of hydraulic oil.

[0042] In the description of this specification, a description referring to terms such as "one embodiment", "several embodiments", "examples", "specific examples", or "several examples" means that the specific features, structures, materials, or characteristics described in combination with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the general expressions of the above terms do not necessarily refer to the same embodiment or example. The specific features, structures, materials, or characteristics described can be appropriately combined in any one or more embodiments or examples. In addition, unless mutually inconsistent, a person skilled in the art can combine different embodiments or examples and features of different embodiments or examples described in this specification.

[0043] The above examples are merely intended to explain the technical ideas and features of the present invention, and are intended to enable those skilled in the art to understand and practice the contents of the present invention, and are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made based on the essence of the contents of the present invention shall be included within the scope of protection of the present invention.

[0044] (Additional Note) (Appendix 1) A multi-stage buffer hydraulic cylinder for a wave energy power generation device, the multi-stage buffer hydraulic cylinder being connected to a wave energy power generation device including a body and a wave absorbing float, the multi-stage buffer hydraulic cylinder for a wave energy power generation device including: a cylinder barrel having a rear end cap and a front end cap at each end and connected to the body; a built-in fixed rod that is coaxially disposed within the cylinder barrel, has a hollow cavity, and extends to a front end cap at a right end thereof, and has a secondary piston attached to the right end thereof; A piston rod is coaxially fitted into the built-in fixed rod, has a hollow cavity, has a primary piston attached to its left end, and is connected to the wave absorbing float at its right end, and constitutes a multi-stage cylinder together with the cylinder barrel and the built-in fixed rod; a hollow cavity of the built-in fixed rod is a fixed rod cavity, a left end of the fixed rod cavity is connected to a primary port, a cavity surrounded by an outer wall of the built-in fixed rod, an inner wall of the piston rod, the primary piston, and the secondary piston is a sealed cavity, a portion of the hollow cavity of the piston rod other than the sealed cavity is a piston rod cavity, a cavity surrounded by an inner wall of the cylinder barrel, the rear end cap, the outer wall of the built-in fixed rod, and the primary piston is a main cavity, the main cavity is connected to a rear port, a cavity surrounded by an inner wall of the cylinder barrel, the front end cap, the outer wall of the piston rod, and the primary piston is a main rod cavity, the main rod cavity is connected to a front port, and the fixed rod cavity is connected to the piston rod cavity, A multi-stage buffered hydraulic cylinder for a wave energy power generation device, characterized in that the main body and the wave absorbing float move relative to each other due to the action of waves, thereby driving the piston rod to reciprocate within the cylinder barrel.

[0045] (Appendix 2) 2. A multi-stage buffered hydraulic cylinder for a wave energy power generation device as described in Appendix 1, further comprising an oil tank and an accumulator, wherein the primary port draws oil from the oil tank through a pipe having a first check valve and pumps hydraulic oil to the accumulator through a pipe having a second check valve, and the rear port and the front port are connected to the oil tank.

[0046] (Appendix 3) 2. A multi-stage buffered hydraulic cylinder for a wave energy power generation device as described in claim 1, characterized in that a front buffer spring is attached to an inner wall adjacent to the front end cap and a rear buffer spring is attached to an inner wall adjacent to the rear end cap.

[0047] (Appendix 4) 2. The multi-stage buffered hydraulic cylinder for a wave energy power generation device described in claim 1, characterized in that a first sealing ring is installed between the piston rod and the front end cap, a second sealing ring is installed between the primary piston and an inner wall of the cylinder barrel, a third sealing ring is installed between an outer wall of the built-in fixed rod and the primary piston, and a fourth sealing ring is installed between the secondary piston and the inner wall of the piston rod.

[0048] (Appendix 5) 2. A multi-stage damped hydraulic cylinder for a wave energy power generation device as described in claim 1, characterized in that the sealed cavity is filled with an inert gas.

[0049] (Appendix 6) A multi-stage buffer hydraulic cylinder for a wave energy power generation device according to any one of appendices 1 to 5 is used, a first control mode used when the wave absorbing float moves upward relative to the main body; a second control mode used when the wave absorbing float moves downward relative to the main body; A third control mode used in a limit wave state of the first control mode; a fourth control mode used in a limit wave state of the second control mode.

[0050] (Appendix 7) The first control mode is A control process in which, when the wave absorbing float moves upward relative to the main body due to wave movement, the piston rod of the hydraulic cylinder also moves upward at the same time, and the main rod cavity of the hydraulic cylinder sucks oil from the oil tank through the front port, and the main cavity of the hydraulic cylinder discharges hydraulic oil to the oil tank through the rear port; and a control process in which, when the piston rod cavity and the fixed rod cavity are filled with hydraulic oil, and the piston rod moves upward, the hydraulic oil in the piston rod cavity and the fixed rod cavity is squeezed out and pumped to the accumulator group through the primary port and the second check valve, energy is stored, and pressure is stabilized to generate electricity, wherein in this process, the gas in the sealed cavity expands.

[0051] (Appendix 8) The second control mode is A multi-stage buffered hydraulic control method according to Appendix 6, characterized in that when the wave absorbing float moves downward relative to the main body due to the action of waves, the piston rod of the hydraulic cylinder also moves downward at the same time, causing the main rod cavity of the hydraulic cylinder to discharge hydraulic oil into the oil tank through the front port, and the main cavity of the hydraulic cylinder to suck oil from the oil tank through the rear port, and when the piston rod moves downward, the piston rod cavity and the fixed rod cavity suck oil from the oil tank through the primary port and the first check valve, and during this process, the gas in the sealed cavity is compressed.

[0052] (Appendix 9) The third control mode is The multi-stage buffer hydraulic control method described in Appendix 6, characterized in that in the case of critical waves, when the wave absorbing float moves upward relative to the main body, the piston rod also moves upward at the same time, and when the primary piston moves to a certain distance from the rear end cap, the primary piston begins to compress the rear buffer spring, and in the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into potential energy of the spring, and finally heat energy is generated, and the main cavity sucks in hydraulic oil through the rear port and discharges it into the oil tank, and the heat is removed by the flow of hydraulic oil.

[0053] (Appendix 10) The fourth control mode is The multi-stage buffer hydraulic control method according to Appendix 6, characterized in that in the case of critical waves, when the wave absorbing float moves downward relative to the body, the piston rod also moves downward at the same time, and when the primary piston moves to a certain distance from the front end cap, the primary piston begins to compress the front buffer spring, and in the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated, and the main rod cavity sucks in the hydraulic oil through the front port and discharges it into the oil tank, and the heat is removed by the flow of the hydraulic oil. [Explanation of symbols]

[0054] 1 Cylinder barrel 2 Rear end cap 3 Primary Port 4 Rear Port 5 Front Port 6 First check valve 7 Second check valve 8 Front End Cap 9 Piston rod 10 Primary piston 11 Built-in fixed rod 12 Secondary piston 13 Front buffer spring 14 Rear buffer spring 15 Main Rod Cavity 16 Main Cavity 17 Piston rod cavity 18 Fixed Rod Cavity 19 Sealed Cavity 20 First sealing ring 21 Second sealing ring 22 Third sealing ring 23 Fourth sealing ring

Claims

1. A multi-stage buffer hydraulic cylinder for a wave energy power generation device, the multi-stage buffer hydraulic cylinder being connected to a wave energy power generation device including a body and a wave absorbing float, the multi-stage buffer hydraulic cylinder for a wave energy power generation device including: a cylinder barrel having a rear end cap and a front end cap at each end and connected to the body; a built-in fixed rod that is coaxially disposed within the cylinder barrel, has a hollow cavity, and extends to a front end cap at a right end thereof, and has a secondary piston attached to the right end thereof; A piston rod is coaxially fitted into the built-in fixed rod, has a hollow cavity, has a primary piston attached to its left end, and is connected to the wave absorbing float at its right end, and constitutes a multi-stage cylinder together with the cylinder barrel and the built-in fixed rod; a hollow cavity of the built-in fixed rod is a fixed rod cavity, a left end of the fixed rod cavity is connected to a primary port, a cavity surrounded by an outer wall of the built-in fixed rod, an inner wall of the piston rod, the primary piston, and the secondary piston is a sealed cavity, a portion of the hollow cavity of the piston rod other than the sealed cavity is a piston rod cavity, a cavity surrounded by an inner wall of the cylinder barrel, the rear end cap, the outer wall of the built-in fixed rod, and the primary piston is a main cavity, the main cavity is connected to a rear port, a cavity surrounded by an inner wall of the cylinder barrel, the front end cap, the outer wall of the piston rod, and the primary piston is a main rod cavity, the main rod cavity is connected to a front port, and the fixed rod cavity is connected to the piston rod cavity, A multi-stage buffered hydraulic cylinder for a wave energy power generation device, characterized in that the main body and the wave absorbing float move relative to each other due to the action of waves, thereby driving the piston rod to reciprocate within the cylinder barrel.

2. 2. The multi-stage buffered hydraulic cylinder for a wave energy power generation device according to claim 1, further comprising an oil tank and an accumulator, wherein the primary port draws oil from the oil tank through a pipe equipped with a first check valve and pumps hydraulic oil to the accumulator through a pipe equipped with a second check valve, and the rear port and the front port communicate with the oil tank.

3. 2. A multi-stage buffered hydraulic cylinder for a wave energy generator as claimed in claim 1, characterized in that a front buffer spring is attached to an inner wall adjacent to the front end cap and a rear buffer spring is attached to an inner wall adjacent to the rear end cap.

4. 2. A multi-stage buffered hydraulic cylinder for a wave energy power generation device as claimed in claim 1, characterized in that a first sealing ring is installed between the piston rod and the front end cap, a second sealing ring is installed between the primary piston and an inner wall of the cylinder barrel, a third sealing ring is installed between an outer wall of the built-in fixed rod and the primary piston, and a fourth sealing ring is installed between the secondary piston and the inner wall of the piston rod.

5. 2. A multi-stage damped hydraulic cylinder for a wave energy power plant according to claim 1, characterized in that the sealed cavity is filled with an inert gas.

6. Using a multi-stage buffer hydraulic cylinder for a wave energy power generation device according to any one of claims 1 to 5, a first control mode used when the wave absorbing float moves upward relative to the body; a second control mode used when the wave absorbing float moves downward relative to the body; A third control mode used in a limit wave state of the first control mode; a fourth control mode used in a limit wave state of the second control mode.

7. The first control mode is The multi-stage buffer hydraulic control method according to claim 6, further comprising: a control process in which, when the wave absorbing float moves upward relative to the body due to wave movement, the piston rod of the hydraulic cylinder also moves upward at the same time, and the main rod cavity of the hydraulic cylinder draws oil from the oil tank through the front port, and the main cavity of the hydraulic cylinder discharges hydraulic oil to the oil tank through the rear port; and a control process in which, when the piston rod cavity and the fixed rod cavity are filled with hydraulic oil, and the hydraulic oil in the piston rod cavity and the fixed rod cavity is squeezed out and pumped to the accumulator group through the primary port and the second check valve, energy is stored, and pressure is stabilized to generate electricity, and in this process, the gas in the sealed cavity expands.

8. The second control mode is The multi-stage buffer hydraulic control method according to claim 6, further comprising: a control process in which, when the wave-absorbing float moves downward relative to the body under the action of waves, the piston rod of the hydraulic cylinder also moves downward at the same time, and the main rod cavity of the hydraulic cylinder discharges hydraulic oil through the front port into the oil tank, and the main cavity of the hydraulic cylinder draws oil from the oil tank through the rear port; and a control process in which, when the piston rod moves downward, the piston rod cavity and the fixed rod cavity draw oil from the oil tank through the primary port and the first check valve, and during this process, the gas in the sealed cavity is compressed.

9. The third control mode is The multi-stage buffer hydraulic control method according to claim 6, further comprising a control process for: in the case of critical waves, when the wave absorbing float moves upward relative to the body, the piston rod also moves upward at the same time; when the primary piston moves to a certain distance from the rear end cap, the primary piston begins to compress the rear buffer spring; in the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated; and the main cavity sucks in the hydraulic oil through the rear port and discharges it into the oil tank, and the heat is removed by the flow of the hydraulic oil.

10. The fourth control mode is The multi-stage buffer hydraulic control method according to claim 6, characterized in that, in the case of critical waves, when the wave absorbing float moves downward relative to the body, the piston rod also moves downward at the same time, and when the primary piston moves to a certain distance from the front end cap, the primary piston begins to compress the front buffer spring, and in the process of compressing the spring, the mechanical energy of the wave absorbing float is converted into the potential energy of the spring, and finally heat energy is generated, and the main rod cavity sucks in the hydraulic oil through the front port and discharges it into the oil tank, and the heat is removed by the flow of the hydraulic oil.

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