Fluid power actuator

Abstract

The invention provides a hydrodynamic actuator which comprises a piston cylinder, a piston, a piston rod for connecting the piston and the outside of the piston cylinder, and a cylindrical piston cylinder sleeve, the piston cylinder sleeve is connected to the outer side of the piston cylinder in a sleeving mode from the first piston cylinder end cover. A sealing piece matched with the inner wall of the piston cylinder sleeve is arranged on the outer wall of the piston cylinder and / or the first piston cylinder end cover; the piston rod penetrates through the first piston cylinder end cover of the piston cylinder and is fixedly connected with the bottom of the piston cylinder sleeve; a first driving fluid cavity is formed between the piston and the first piston cylinder end cover; a second driving fluid cavity is formed between the first piston cylinder end cover and the piston cylinder sleeve; a fluid rotation cavity is formed between the piston and the second piston cylinder end cover. The technical scheme can be widely applied to the field of force transmission components such as hydraulic cylinders and pneumatic cylinders.

Description

Technical Field

[0001] The present invention relates to a device using a fluid as a driving force transmission medium, such as a hydraulic cylinder or a pneumatic cylinder. Background Art

[0002] Fluid power actuators such as hydraulic cylinders and pneumatic cylinders can utilize the pressure of a fluid to achieve mechanical motion and have wide applications in fields such as industry and transportation. Fluid power actuators are divided into single-acting fluid power actuators and double-acting fluid power actuators.

[0003] Existing double-acting fluid power actuators (taking a double-acting hydraulic cylinder as an example) usually need to be provided with oil inlets and outlets at both ends of the hydraulic cylinder and matching oil circuits, so as to supply oil to the spaces on both sides of the piston in the hydraulic cylinder respectively, and then drive the piston to reciprocate in the piston cylinder. Existing double-acting fluid power actuators have the following problems:

[0004] 1. When the piston rod moves in one direction and bears compressive stress, in order to be able to bear the corresponding pressure and avoid structural deformation, it is necessary to have a relatively large cross-sectional area of the piston rod. Especially when the length of the piston rod is relatively large, for example, when the stroke of the piston reaches 5 to 10 meters, a larger cross-sectional area of the piston rod is required. This increases the overall volume of the hydraulic cylinder.

[0005] 2. The oil circuits provided for supplying oil to both ends of the hydraulic cylinder occupy a relatively large space. At the same time, longer oil circuits require more protection measures to prevent the oil circuits from being damaged due to exposure to a harsh working environment. Summary of the Invention

[0006] In order to solve the problem that existing double-acting fluid power actuators need to occupy a relatively large space, the present invention provides a fluid power actuator.

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

[0008] A fluid power actuator includes a piston cylinder, a piston disposed in the piston cylinder and capable of reciprocating along the axis of the piston cylinder, a piston rod connecting the piston to the outside of the piston cylinder, and a first piston cylinder end cap and a second piston cylinder end cap disposed at both ends in the axial direction of the piston cylinder. The fluid power actuator further includes a cylindrical piston cylinder sleeve; the piston cylinder sleeve is sleeved on the outside of the piston cylinder from the first piston cylinder end cap; a seal matching the inner wall of the piston cylinder sleeve is disposed on the outer wall of the piston cylinder and / or the first piston cylinder end cap; the piston rod passes through the first piston cylinder end cap of the piston cylinder and is fixedly connected to the bottom of the piston cylinder sleeve; a first driving fluid chamber is formed between the piston and the first piston cylinder end cap; a second driving fluid chamber is formed between the first piston cylinder end cap and the piston cylinder sleeve; and a fluid return chamber is formed between the piston and the second piston cylinder end cap.

[0009] Optionally, a first fluid passage and a second fluid passage are provided in the piston rod; the first fluid passage communicates with the first driving fluid chamber; the second fluid passage communicates with the fluid rotating chamber.

[0010] Optionally, a cooling fluid passage is provided in the piston rod; the cooling fluid passage communicates with the fluid rotating chamber.

[0011] Optionally, a diversion pipe is slidably provided in the cooling fluid passage; the diversion pipe is connected to the second piston cylinder end cover, or the diversion pipe is connected to the inner wall of the piston cylinder; the diversion pipe is provided with a diversion through hole.

[0012] Optionally, a diversion disc is provided adjacent to the second piston cylinder end cover; the diversion disc has a disc body extending radially along the fluid rotating chamber, and a flow passage is provided in the disc body; the flow passage communicates with the diversion through hole and also communicates with the fluid rotating chamber.

[0013] Optionally, a stroke stop valve is provided at the bottom of the piston cylinder sleeve adjacent to the cooling fluid passage; the stroke stop valve includes a valve core and an elastic member that can expand and contract along the axis direction of the cooling fluid passage; one end of the elastic member in the elastic direction is fixedly connected to the inner wall of the cooling fluid passage, and the other end of the elastic member in the elastic direction presses against the valve core; a first passage through hole and a second passage through hole are respectively provided on the wall of the cooling fluid passage; the first passage through hole communicates with the first fluid passage; the second passage through hole communicates with the second fluid passage; a conduction structure is provided on the valve core; within the range of the expansion and contraction of the elastic member, there is a position where the conduction structure conducts the first passage through hole and the second passage through hole.

[0014] Optionally, a stroke stop hole is provided on the side wall of the piston cylinder sleeve that penetrates the side wall of the piston cylinder sleeve.

[0015] Optionally, a filter element is provided adjacent to the inner side wall of the piston cylinder sleeve in the stroke stop hole; the surface of the filter element facing the inner side of the piston cylinder sleeve is flush with the inner side wall surface of the piston cylinder sleeve.

[0016] Optionally, the stroke stop hole communicates with a fluid collection container provided outside the second driving fluid chamber.

[0017] Optionally, the fluid collection container is provided with a one-way air valve; the conduction direction of the one-way air valve is from the outside to the inside of the fluid collection container.

[0018] The technical effects of the present invention are as follows:

[0019] The hydrodynamic actuator of the present invention can be driven using gas or liquid as the medium. For example, when the fluid is filled into the second drive fluid chamber, the drive piston cylinder presses against the external load; when the fluid is filled into the first drive fluid chamber, the drive piston cylinder withdraws from the external load. It can be seen that the piston cylinder of the hydrodynamic actuator of the present invention serves as a load-bearing component to bear the external load, especially bearing compressive stress when bearing the load, while the piston rod only bears tensile stress when the fluid is filled into the first drive fluid chamber.

[0020] Since it does not need to bear the main compressive stress, the strength requirement for the piston rod is reduced, and accordingly, the volume of the hydrodynamic actuator can be reduced. In addition, both the first drive fluid chamber and the second drive fluid chamber are located on one side of the hydrodynamic actuator, so the long-distance layout of the oil circuit can be avoided, reducing the occupied space and at the same time reducing the probability of the oil circuit being damaged. In summary, the technical solution of the present invention achieves the purpose of the present invention.

[0021] The further effects of the above optional methods will be described in combination with specific embodiments below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic structural diagram of an embodiment of the present invention.

[0023] Figure 2 is Figure 1 a partial enlarged view of the shown embodiment.

[0024] Figure 3 is Figure 1 a three-dimensional sectional view of the shown embodiment.

[0025] Figure 4 is Figure 1 a partial enlarged view of the shown embodiment.

[0026] Figure 5 is Figure 4 another working state diagram of the shown part.

[0027] The reference numerals in the drawings are explained as follows:

[0028] 101, stroke stop valve; 102, second fluid passage; 103, second drive fluid chamber; 104, piston cylinder sleeve; 105, first piston cylinder end cover; 106, sealing ring; 107, stroke stop hole; 108, one-way air valve; 109, fuel tank; 110, one-way air valve; 111, fuel tank; 112, piston cylinder; 113, second piston cylinder end cover; 114, load; 115, deflector disc; 116, deflector tube; 117, fluid rotary chamber; 118, piston; 119, first drive fluid chamber; 120, first fluid passage; 121, piston rod; 122, cooling fluid passage;

[0029] 201, Screw; 202, Filter element; 203, Seal; 204, Cleaning hole; 205, Cleaning hole; 206, Seal;

[0030] 401, Plug; 402, Spring; 403, Second channel through-hole; 404, Filter screen; 405, Conducting ring groove; 406, Spool; 407, Cooling fluid inlet and outlet; 408, Positioning flange; 409, Positioning groove; 410, Filter screen; 411, First channel through-hole. Detailed implementation manner

[0031] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Figure 1 Shows the main structure of an example of the fluid power actuator of the present invention. Figure 1 The shown embodiment can use liquid as the driving medium, or can use gas as the driving medium. For the convenience of description, the following takes liquid (hydraulic oil) as the driving medium as an example for description.

[0033] As Figure 1 shown, the fluid power actuator of the present invention includes a piston cylinder 112, a piston 118 disposed in the piston cylinder 112 and capable of reciprocating along the axis direction of the piston cylinder 112, and a piston rod 121 connected to the piston 118. One end of the piston rod 121 is connected to the piston 118, and the other end is connected to the outside of the piston cylinder 112. At both ends of the piston cylinder 112 along the axis are provided a first piston cylinder end cover 105 and a second piston cylinder end cover 113 that enclose the piston cylinder 112. The piston rod 121 penetrates through the first piston cylinder end cover 105. The main structures of the above piston cylinder 112, piston 118, and piston rod 121 are the same as those of conventional piston cylinder components. The cavity between the piston 118 and the first piston cylinder end cover 105 is the first driving fluid cavity 119; the cavity between the piston 118 and the second piston cylinder end cover 113 is the fluid rotary cavity 117.

[0034] As Figure 1 shown, the fluid power actuator further includes a piston cylinder sleeve 104. Refer to Figure 3It can be seen that the piston cylinder liner 104 is a cylindrical component. The opening of the piston cylinder liner 104 is sleeved on the outside of the piston cylinder 112 starting from the first piston cylinder end cover 105 of the piston cylinder 112, and finally the piston cylinder liner 104 is sleeved on the outside of the piston cylinder 112. The end of the piston rod 121 is fixedly connected to the bottom of the piston cylinder liner 104. The outer diameter of the piston cylinder 112 matches the inner diameter of the piston cylinder liner 104, and an annular sealing ring 106 is provided on the outer wall of the piston cylinder 112, so that the piston cylinder 112 can slide left and right in the piston cylinder liner 104, and this sliding direction is consistent with the reciprocating movement direction of the piston 118 in the piston cylinder 112. When the piston cylinder 112 moves away from the piston cylinder liner 104, a second driving fluid chamber 103 is formed between the first piston cylinder end cover 105 and the piston cylinder liner 104.

[0035] A stroke stop hole 107 is provided on the side wall of the piston cylinder liner 104. The stroke stop hole 107 is a hole penetrating the side wall of the piston cylinder liner 104. Figure 2 The specific structure near the stroke stop hole 107 is shown. As Figure 2 shown, a filter element 202 is provided at the inner side wall of the piston cylinder liner 104 adjacent to the stroke stop hole 107. The filter element 202 has a mesh filter structure. The surface of the filter element 202 facing the inside of the piston cylinder liner 104 is flush with the inner side wall surface of the piston cylinder liner 104. Here, "flush" means that the setting of the filter element 202 does not form a structure protruding or recessed from the inner side surface of the piston cylinder liner 104 at the stroke stop hole 107. For example, in this embodiment, the surface of the filter element 202 is an arc surface with the same curvature as the inner side surface of the piston cylinder liner 104. The screw 201 is screwed into the side wall of the piston cylinder liner 104 from the outside of the piston cylinder liner 104, and then presses against the filter element 202.

[0036] As Figure 2 shown, a cleaning hole 205 is provided at the end of the piston cylinder liner 104 away from the bottom (i.e., the right end of the piston cylinder liner 104 in Figure 1 and Figure 2 ), and a cleaning hole 204 is provided on the side wall of the piston cylinder liner 104. The cleaning hole 204 penetrates the side wall of the piston cylinder liner 104. The cleaning hole 204 communicates with the cleaning hole 205. Annular seals 203 and 206 are respectively provided on the left and right sides of the inner side wall of the piston cylinder liner 104 adjacent to the cleaning hole 204.

[0037] As Figure 1 shown, the stroke stop hole 017 communicates with an oil tank 109 provided outside the piston cylinder liner 104. The oil tank 109 is further communicated with an oil tank 111. A one-way air valve 108 and a pressure monitor are provided at the upper top in the gravity direction of the oil tank 109. A one-way air valve 110 and a pressure monitor are provided at the upper top in the gravity direction of the oil tank 111.

[0038] As Figure 1 shown, a first fluid passage 120 and a second fluid passage 102 are provided in the piston rod 121. One end of the first fluid passage 120 is provided at the left end of the piston rod 121 and communicates with the oil passage outside the piston cylinder sleeve 104; the other end of the first fluid passage 120 ( Figure 1 the right end in Figure 1 ) communicates with the first driving fluid chamber 119. One end of the second fluid passage 102 is provided at the left end of the piston rod 121 and communicates with the oil passage outside the piston cylinder sleeve 104; the other end of the second fluid passage 102 (

[0039] As Figure 1 shown, a cooling fluid passage 122 is further provided in the piston rod 121. Referring to Figure 4 , at the left end of the cooling fluid passage 122, the cooling fluid passage 122 communicates with the external oil passage through the cooling fluid inlet / outlet 407. As Figure 1 shown, the left end of the guide pipe 116 is inserted into and arranged in the cooling fluid passage 122 from the right end of the cooling fluid passage 122. The right end of the guide pipe 116 is connected to the guide disk 115. The guide disk 115 is a disk-shaped component arranged on the second piston cylinder end cover 113. Referring to Figure 3 , a flow passage is provided in the guide disk 115, and the flow passage communicates with the inside of the guide pipe 116 through the flow-through holes provided on the guide pipe 116. A through hole communicating with the fluid rotary chamber 117 is provided on the flow passage of the guide disk 115. With the relative movement between the piston cylinder 112 and the piston cylinder sleeve 104, the guide pipe 116 can always slide in the cooling fluid passage 122.

[0040] As Figure 1 shown, a stroke stop valve 101 is provided at the left end of the cooling fluid passage 122, that is, adjacent to the bottom of the piston cylinder sleeve 104. Figure 4 And Figure 5 further shows the specific structure and two working states of the stroke stop valve 101. As Figure 4 And Figure 5 shown, the plug 401 is fixed on the inner wall of the cooling fluid passage 122 and blocks the left end of the cooling fluid passage 122. A spring 402 and a valve core 406 are sequentially arranged in the cooling fluid passage 122 on the right side of the plug 401. The telescopic direction of the spring 402 is consistent with the axial direction of the cooling fluid passage 122.

[0041] As Figure 4 And Figure 5As shown, the main body of the valve core 406 is in the shape of a column, and the axis of the column is coaxial or parallel to the axis of the cooling fluid channel 122. The radially protruding positioning flange 408 of the valve core 406 matches the positioning groove 409 provided on the inner wall of the cooling fluid channel 122, so that the movement range of the valve core 406 along the axis of the cooling fluid channel 122 is determined within the dimension range of the positioning groove 409 along the axis direction of the cooling fluid channel 122. A conduction ring groove 405 is provided on the side surface of the column of the valve core 406. The conduction ring groove 405 is an annular groove provided on the surface of the valve core 406. Sealing rings are also provided on the side surfaces of the column of the valve core 406 on the left and right sides of the conduction ring groove 405 respectively.

[0042] As Figure 4 and Figure 5 shown, a first channel through-hole 411 and a second channel through-hole 403 are provided on the cooling fluid channel 122. The first channel through-hole 411 communicates the cooling fluid channel 122 and the first fluid channel 120, and a filter screen 410 is provided in the first channel through-hole 411. The second channel through-hole 403 communicates the cooling fluid channel 122 and the second fluid channel 102, and a filter screen 404 is provided in the second channel through-hole 403.

[0043] The working process of the following Figure 1 shown embodiment will be described to further clarify the technical solution of the present invention. Figure 1 The working process of the shown embodiment is described separately according to the strokes of the piston cylinder 112 in the right and left directions.

[0044] The piston cylinder 112 moves to the right

[0045] As Figure 1 shown, high-pressure hydraulic oil is injected into the second driving fluid chamber 103 (injected through the injection port provided at the bottom of the piston cylinder sleeve 104). Under the action of the hydraulic oil pressure, the piston cylinder 112 moves to the right until it reaches the working state of pressing against the load 114.

[0046] Referring to Figure 4 , when the piston cylinder 112 moves to the right, the volume of the fluid rotation chamber 117 increases to generate a negative pressure, and then the cooling fluid is injected into the cooling fluid channel 122 through the cooling fluid inlet and outlet 407. The cooling fluid entering the cooling fluid channel 122 enters the fluid rotation chamber 117 along the cooling fluid channel 122, the guide pipe 116, and the guide disk 115, and cools the piston cylinder 112 in the part of the fluid rotation chamber 117. The arrangement of the guide pipe 116 and the guide disk 115 enables the right end part of the piston cylinder 112 to also have cooling fluid flowing for cooling.

[0047] When the piston cylinder 112 moves to the right and the left end of the piston cylinder 112 reaches the stroke stop hole 107, the stroke stop hole 107 communicates with the second driving fluid chamber 103. The high-pressure hydraulic oil in the second driving fluid chamber 103 flows into the fuel tank 109 through the stroke stop hole 107, causing the pressure in the second driving fluid chamber 103 to rapidly decrease, and the moving speed of the piston cylinder 112 to rapidly decrease to 0. The setting and working mode of the stroke stop hole 107 can avoid the adverse effects caused by inertia at the right stroke termination position of the piston cylinder 112 (such as impact on the load 114, separation of the piston cylinder 112 from the piston cylinder sleeve 104, etc.). The surface of the filter element 202 facing the inner side of the piston cylinder sleeve 104 is flush with the inner wall surface of the piston cylinder sleeve 104, so that when the piston cylinder 112 moves, the sealing ring 106 will not cause wear effect with the edge of the hole when passing through the stroke stop hole 107.

[0048] If there is too much hydraulic oil in the fuel tank 109, it can flow into the fuel tank 111 through the overflow port. The conduction directions of the one-way air valves 108 and 110 on the fuel tank 109 and the fuel tank 111 are from the outside to the inside of the fuel tank, enabling the fuel tanks 109 and 111 to balance with the external air pressure. At the same time, the set air pressure monitor can monitor the pressure in the fuel tank to avoid excessive pressure in the fuel tank. The fuel tank 111 can be set as a large hydraulic oil storage container, which is connected to the hydraulic oil supply oil circuit and the return oil circuit to form a circulating hydraulic oil system.

[0049] The piston cylinder 112 moves to the left

[0050] As Figure 1 shown, high-pressure hydraulic oil is injected into the first driving fluid chamber 119 through the first fluid channel 120. Under the action of the hydraulic oil pressure, the piston cylinder 112 moves to the left to remove the top pressure on the load 114.

[0051] When the piston cylinder 112 moves to the left, a negative pressure is formed in the stroke stop hole 107, thereby sucking the hydraulic oil in the fuel tank 109 into the gap between the piston cylinder 112 and the piston cylinder sleeve 104 to play a lubricating role. The filter element 202 can prevent impurities in the hydraulic oil from entering the gap between the piston cylinder 112 and the piston cylinder sleeve 104.

[0052] Refer to Figure 1 and Figure 4 , when the piston cylinder 112 moves to the left, the volume of the fluid rotary chamber 117 decreases, and the pressure inside it increases. Then, the cooling fluid in the fluid rotary chamber 117 is driven to flow out through the guide disk 115, the guide pipe 116, the cooling fluid channel 122, and then out through the cooling fluid inlet and outlet 407, thereby taking away heat. In this embodiment, the cooling fluid uses the same hydraulic oil as that driving the piston cylinder 112. When the piston cylinder 112 moves to the left, part of the cooling fluid also flows out through the second fluid channel 102.

[0053] When the piston cylinder 112 moves leftward to the end of its stroke, in order to avoid the impact of the first piston cylinder end cover 105 on the bottom of the piston cylinder sleeve 104 caused by inertia, a stroke stop valve 101 and other shock prevention structures are provided. For details, refer to Figure 4 and Figure 5 . As Figure 4 shown, when the piston cylinder 112 has not reached the left end of its stroke, under the elastic support of the spring 402, the positioning flange 408 of the valve core 406 presses against the right edge of the positioning groove 409, and thus the valve core 406 is positioned. When the piston cylinder 112 moves leftward, the pressure generated by the backflow of the cooling fluid compresses the spring 402. When the piston cylinder 112 approaches the left end of its stroke, the pressure generated by the backflow of the cooling fluid further increases, thereby pushing the valve core 406 to the state as shown in Figure 5 . When reaching the state as shown in Figure 5 , the conducting ring groove 405 on the valve core 406 aligns with the first channel through hole 411 and the second channel through hole 403 simultaneously, enabling the first fluid channel 120 and the second fluid channel 102 to be conducted through the conducting ring groove 405, that is, the first driving fluid chamber 119 is conducted with the fluid rotating chamber 117, and the pressure difference between the two chambers suddenly decreases, thereby rapidly reducing the moving speed of the piston cylinder 112 to 0. The filter screens 404 and 410 can intercept impurities. The sealing rings arranged on the left and right sides of the conducting ring groove 405 around the valve core 406 can ensure the sealing of the flow channel when the conducting ring groove 405 conducts the first channel through hole 411 and the second channel through hole 403.

[0054] As can be seen from the working process of the fluid power actuator of the present invention above, when the piston cylinder 112 moves rightward, the piston rod 121 does not need to bear the main pressure of the top load 114; when the piston cylinder 112 moves leftward, the piston rod 121 only needs to bear a small tensile stress. Therefore, the technical solution of the present invention reduces the strength requirement for the piston rod 121, enabling the piston rod 121 to reduce its volume and fluid channels can be arranged therein.

[0055] During the reciprocating movement of the piston cylinder 112, since the sealing ring 106 plays a main sealing role, the sealing degree requirements for the seals 203 and 206 can be reduced. Thus, it is feasible to engrave scales on the outer wall of the piston cylinder 112 by laser, and the stroke range of the piston cylinder 112 can be more accurately grasped. Although certain leakage will occur when the concave scale passes through the seals 203 and 206, with the reduced sealing degree requirements for the seals 203 and 206, such leakage is within the allowable range.

[0056] Figure 2The cleaning holes 204 and 205 shown can be blocked when not in use. When it is necessary to clean the impurities accumulated on the right side of the seal 203 after the piston cylinder 112 has worked for a period of time, the blockage can be removed and high-pressure gas can be introduced through the cleaning hole 205 for purging. In other embodiments, a plurality of cleaning holes 204 can be provided along the circumferential direction of the piston cylinder sleeve 104, and an annular purging channel is formed at the plurality of cleaning holes 204 in the gap between the piston cylinder 112 and the piston cylinder sleeve 104, and impurities are discharged from the plurality of cleaning holes 204 by using this purging channel.

[0057] It should be noted that the above are only the preferred embodiments of the present invention, and thus do not limit the patent protection scope of the present invention. The present invention can also be replaced with equivalent technologies. Therefore, all equivalent changes made by using the description and illustration content of the present invention, directly or indirectly applied to other related technical fields, are included in the scope covered by the present invention.

Claims

1. A hydrodynamic actuator, comprising a piston cylinder, a piston disposed within the piston cylinder and reciprocating along the axis of the piston cylinder, a piston rod connecting the piston to the outside of the piston cylinder, and a first piston cylinder end cap and a second piston cylinder end cap disposed at two ends of the piston cylinder in the axial direction thereof, characterized in that: It further includes a cylindrical piston cylinder liner; the piston cylinder liner is sleeved on the outside of the piston cylinder from the first piston cylinder end cover; a seal matching the inner wall of the piston cylinder liner is provided on the outer wall of the piston cylinder and / or the first piston cylinder end cover; the piston rod penetrates through the first piston cylinder end cover of the piston cylinder and is fixedly connected to the bottom of the piston cylinder liner; a first driving fluid chamber is formed between the piston and the first piston cylinder end cover; a second driving fluid chamber is formed between the first piston cylinder end cover and the piston cylinder liner; a fluid rotation chamber is formed between the piston and the second piston cylinder end cover.

2. The hydrodynamic actuator according to claim 1, wherein: A first fluid passage and a second fluid passage are provided in the piston rod; the first fluid passage is communicated with the first driving fluid chamber; the second fluid passage is communicated with the fluid rotation chamber.

3. The hydrodynamic actuator according to claim 2, characterized in that: A cooling fluid passage is provided in the piston rod; the cooling fluid passage is communicated with the fluid rotation chamber.

4. The hydrodynamic actuator according to claim 3, characterized in that: A flow guide pipe is slidably arranged in the cooling fluid passage; the flow guide pipe is connected to the second piston cylinder end cover, or the flow guide pipe is connected to the inner wall of the piston cylinder; the flow guide pipe is provided with a flow guiding through hole.

5. A hydrodynamic actuator according to claim 4, characterized in that: A flow guide disc is provided adjacent to the second piston cylinder end cover; the flow guide disc has a disc body extending radially along the fluid rotation chamber, and a flow passage is provided in the disc body; the flow passage is communicated with the flow guiding through hole and is also communicated with the fluid rotation chamber.

6. The hydrodynamic actuator according to claim 4, wherein: A stroke stop valve is provided at the bottom of the cooling fluid passage adjacent to the piston cylinder liner; the stroke stop valve includes a valve core and an elastic member that can expand and contract along the axis direction of the cooling fluid passage; one end in the elastic direction of the elastic member is fixedly connected to the inner wall of the cooling fluid passage, and the other end in the elastic direction of the elastic member presses against the valve core; a first passage guiding through hole and a second passage guiding through hole are respectively provided on the wall of the cooling fluid passage; the first passage guiding through hole is communicated with the first fluid passage; the second passage guiding through hole is communicated with the second fluid passage; a conducting structure is provided on the valve core; within the range of the expansion and contraction of the elastic member, there is a position where the conducting structure conducts the first passage guiding through hole and the second passage guiding through hole.

7. The hydrodynamic actuator according to claim 1, characterized in that: A stroke stop hole penetrating through the side wall of the piston cylinder liner is provided on the side wall of the piston cylinder liner.

8. The hydrodynamic actuator according to claim 7, characterized in that: A filter element is provided adjacent to the inner side wall of the piston cylinder liner in the stroke stop hole; the surface of the filter element facing the inner side of the piston cylinder liner is flush with the inner side wall surface of the piston cylinder liner.

9. The hydrodynamic actuator according to claim 7, characterized in that: The stroke stop hole is communicated with a fluid collection container arranged outside the second driving fluid chamber.

10. A hydrodynamic actuator according to claim 9, wherein: The fluid collection container is provided with a one-way air valve; the conducting direction of the one-way air valve is from the outside to the inside of the fluid collection container.

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