Pressurizing oil tank for electro-hydrostatic actuator

Abstract

The invention provides a pressurizing oil tank for an electro-hydrostatic actuator, which is characterized by comprising a shell (1), a piston (2), a spring (3), a spring seat (4), an end cover (6) and a liquid filling tool (10), and the piston (2) divides the pressurizing oil tank into a liquid cavity (8) and a spring cavity (9); the liquid cavity (8) is communicated with a system oil way; the left side and the right side of the spring (3) abut against the piston (2) and the spring seat (4) respectively; the spring seat (4) is arranged on the inner side of the end cover (6), and the end cover (6) is in threaded connection with the shell (1); scale marks (21) are arranged on the piston (2) so as to monitor the liquid level of the oil tank; and the liquid filling volume is controlled by controlling the depth of the liquid filling tool (10) screwed into the shell (1). Through the simple structure, the pressurization and fine adjustment functions of the oil tank are achieved, the liquid filling amount of the oil tank can be accurately controlled, meanwhile, the daily monitoring of the liquid level can be achieved, and the oil tank has the advantages of being simple in structure, low in cost and complete in function.

Description

Technical Field

[0001] This invention relates to electro-hydraulic actuators, and more particularly to pressurized oil tanks for electro-hydraulic actuators. Background Technology

[0002] In electro-hydraulic actuators, the booster tank provides back pressure to the system, ensuring the pump's self-priming performance and preventing cavitation. Spring-boosted or gas-boosted types are commonly used. Traditional booster tanks have some drawbacks, such as the invisibility of the internal structure of the oil during filling, making it difficult to determine the amount of liquid already filled, resulting in inaccurate filling volume and consequently, difficulty in precisely controlling the back pressure of the booster tank. Furthermore, it is difficult to determine whether leaks or other problems have occurred in the electro-hydraulic actuator during daily operation. Summary of the Invention

[0003] To address these issues, this invention proposes a low-cost solution that overcomes the shortcomings of existing booster tanks.

[0004] The objective of this invention can be achieved through the following technical solutions: A booster tank for an electro-hydraulic actuator is characterized by comprising a housing 1, a piston 2, a spring 3, a spring seat 4, an end cap 6, and a filling fixture 10. The piston 2 divides the booster tank into a liquid chamber 8 and a spring chamber 9. The liquid chamber 8 is connected to the system oil circuit. The spring 3 is disposed in the spring chamber 9, and the spring 3 is used for pressurization. The left and right sides of the spring 3 abut against the piston 2 and the spring seat 4, respectively. Spring seat 4 is located inside end cover 6. End cover 6 and housing 1 are connected by threads. The pressure is adjusted by adjusting the depth of the threads. During assembly, the end face of end cover 6 is flush with the end face of housing 1. Piston 2 is pushed against the bottom of housing 1 by spring 3. Piston 2 has scale line 21 to monitor the oil tank level. There are external threads on the outside of the housing 1 and internal threads on the filling fixture 10. The two are connected by threads. When filling, the filling fixture 10 is screwed into the housing 1 first. As the volume of oil in the pressurized oil tank increases, the piston 2 will gradually extend outward until the piston 2 hits the filling fixture 10, and the filling step is completed. The filling volume is controlled by controlling the depth of the filling fixture 10 screwed into the housing 1.

[0005] Furthermore, a seal 7 is provided between the piston 2 and the housing 1. The seal 7 adopts a combination of AQ seal + 2 side wear-resistant rings to achieve effective gas-liquid isolation.

[0006] Furthermore, a needle roller bearing 5 is placed between the end cap 6 and the spring seat 4 to reduce the resistance when the end cap 6 is screwed in, making it easier to adjust the end cap 6.

[0007] Furthermore, the piston 2 comprises two parts, namely the piston section 21 and the guide section 22. The piston section 21 is fitted with the housing 1 through the seal 7, and the guide section 22 is fitted with the end cap 6 with clearance.

[0008] Furthermore, the piston section 21 has a sealing groove 23 for installing a sealing ring, which mates with the housing 1; the guide section 22 has a scale line 24, which mates with the end cap 6, and the scale line 24 is used to determine the oil level in the tank.

[0009] Furthermore, after the filling is completed, the filling fixture 10 is unscrewed from the housing 1. At this time, the back pressure of the booster tank is determined by the compression of the spring 3. If it is necessary to increase the back pressure of the system, the end cap 6 is screwed into the housing 1. If it is necessary to decrease the back pressure of the system, the end cap 6 is screwed out of the housing 1.

[0010] Furthermore, during operation, due to factors such as temperature changes and external leakage of the actuator, the volume of the actuator oil changes. At this time, the piston 2 will move accordingly, and the amount of oil volume change can be judged by the scale line 21 outside the piston rod extending from the end cover 6.

[0011] Furthermore, the end cap 6 is annular, with a guide hole 41 in the middle and a connecting thread 42 on the outside. There are multiple circular holes 43 distributed in a circle on the annular end face. The end cap 6 is connected to the housing 1 by the thread and its screw-in depth is adjusted by the circular holes 43.

[0012] Compared with the prior art, the present invention has the following advantages: This invention, through its simple structure, achieves both pressurization and fine-tuning of the fuel tank, precise control of the fuel tank filling volume, and daily monitoring of the fuel level. It features a simple structure, low cost, and comprehensive functions. Attached Figure Description

[0013] Figure 1 This is a structural diagram of the booster tank for the electro-hydraulic actuator of the present invention; Figure 2 This is a diagram of the piston structure of the present invention; Figure 3 This is a structural diagram of the end cap of the present invention.

[0014] Explanation of reference numerals in the attached figures: 1. Housing, 2. Piston, 3. Spring, 4. Spring seat, 5. Needle roller bearing, 6. End cap, 7. Seal, 8. Liquid chamber, 9. Spring chamber, 10. Filling fixture, 21. Piston section, 22. Guide section, 23. Sealing groove, 24. Scale line, 25. Piston internal thread, 41. Guide hole, 42. Connecting thread, 43. Round hole. Detailed Implementation

[0015] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0016] The present invention provides a booster tank for an electro-hydraulic actuator, which is composed of a shell, piston, spring, end cover, spring seat, needle roller bearing, seals, and filling fixture, etc. It has the advantages of simple structure and low cost, and can be widely used in electro-hydraulic actuators.

[0017] The pressurized oil tank of the present invention can not only adjust the pressurization pressure, monitor the oil level, and accurately control the filling volume.

[0018] like Figure 1 As shown, this invention provides a booster tank for an electro-hydraulic actuator, comprising a housing 1, a piston 2, a spring 3, a spring seat 4, a needle roller bearing 5, an end cap 6, a seal 7, and a filling fixture 10. The piston 2 divides the booster tank into a liquid chamber 8 and a spring chamber 9. The spring 3 is located in the spring chamber 9, and pressure is increased by the spring 3, which abuts against the piston 2 and the spring seat 4 on its left and right sides, respectively. The spring seat 4 is located inside the end cap 6, and the end cap 6 and the housing 1 are connected by threads. The booster pressure can be adjusted by adjusting the depth of the threads. The piston 2 has graduations for monitoring the tank level. The housing 1 has threads on its outer side, which, when used with the filling fixture 10, allows for precise control of the filling volume. A needle roller bearing 5 is placed between the end cap 6 and the spring seat 4 to reduce the resistance when the end cap 6 is screwed in, making adjustment easier. The seal 7 is located between the piston 2 and the housing 1.

[0019] Figure 2 This is a diagram of the piston structure of the present invention. Figure 2 As shown, piston 2 comprises two parts: piston section 21 and guide section 22. Piston section 21 engages with housing 1 via seal 7, while guide section 22 forms a clearance fit with end cap 6. Piston section 21 has a sealing groove 23 for installing a sealing ring, which engages with housing 1. Guide section 22 has graduations 24, which engage with end cap 6, allowing for the determination of the oil level in the tank. Guide section 22 also has an internal thread 25, which, when used with external threaded fixtures, allows for adjustment of piston 2's position within housing 1 during installation or adjustment, facilitating piston 2 installation and adjustment.

[0020] Figure 3 This is a structural diagram of the end cap of the present invention. Figure 3As shown, the housing 1 and end cap 6 are connected by threads. The end cap 6 has several circumferentially distributed circular holes to facilitate adjustment of the screw-in depth, thereby regulating the back pressure of the oil tank. The end cap 6 is annular, with a guide hole 41 in the center and connecting threads 42 on the outer side. Several circumferentially distributed circular holes 43 are located on the annular end face. The end cap 6 is connected to the housing 1 by threads, and its screw-in depth can be adjusted through the circular holes 43. The seal 7 generally adopts a combination of an AQ seal and two wear-resistant rings on both sides to achieve effective gas-liquid isolation. Through the piston 2 and the seal 7, the space inside the housing 1 is divided into a liquid chamber 8 and a spring chamber 9.

[0021] The outer shell 1 has external threads, and the filling fixture 10 has internal threads. The two are connected by threads. By controlling the screw-in depth of the filling fixture 10 and the shell 1, the filling amount of the oil tank can be controlled.

[0022] In use, the booster tank can be connected to actuators via flange connections, threaded connections, etc., and the liquid chamber 8 is connected to the system oil circuit. During assembly, the end face of the end cap 6 is flush with the end face of the housing 1, and the piston 2 will be pressed against the bottom of the housing 1 by the action of the spring 3. During filling, first screw the filling fixture 10 onto the housing 1. As the volume of oil in the booster tank's liquid chamber increases, the piston 2 will gradually extend outward, and the pressure in the liquid chamber will increase from the minimum pressure. p min Gradually increase to rated pressure p 0. At this point, the oil volume in the liquid chamber can no longer increase after the piston 2 reaches the filling fixture 10, completing the filling step. The filling volume can be controlled by controlling the depth to which the filling fixture 10 is screwed into the housing 1. Let the inner diameter of the booster tank be... D In order to achieve the rated filling volume V 0, the rated compression distance can be adjusted by changing the screw-in depth. L 0 represents...

[0023]

[0024] The replenishment pressure of the booster tank is determined by the spring stiffness and its operating point, specifically for the filling volume. V Rated back pressure at 0 p 0 and system minimum back pressure p min Requirements for spring stiffness k and initial compression s 0 should satisfy the following formula

[0025] After filling is complete, the filling fixture 10 can be unscrewed from the housing 1. At this point, the back pressure of the booster tank is determined by the compression of the spring 3. If it is necessary to increase the system back pressure, screw the end cap 6 into the housing 1; if it is necessary to decrease the system back pressure, screw the end cap 6 out of the housing 1. System back pressure p The distance Δ between the spin-in and spin-out states has the following relationship:

[0026] During operation, factors such as temperature changes and external leakage of the actuator can cause changes in the volume of the actuator oil. At this time, the piston 2 will move accordingly, and the amount of oil volume change can be judged by the scale line 21 on the piston rod extending out of the end cover 6. The number and spacing of the scale line 21 can be marked according to the actual engineering needs.

[0027] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A booster tank for an electro-hydraulic actuator, characterized in that, Includes housing (1), piston (2), spring (3), spring seat (4), end cap (6), and filling fixture (10). Piston (2) divides the pressurized oil tank into liquid chamber (8) and spring chamber (9). Liquid chamber (8) is connected to the system oil circuit. Spring (3) is installed in spring chamber (9) and pressurization is achieved by spring (3). Spring (3) abuts against piston (2) and spring seat (4) on the left and right sides, respectively. The spring seat (4) is located inside the end cover (6). The end cover (6) and the housing (1) are connected by threads. The pressure is adjusted by adjusting the depth of the threads. During assembly, the end face of the end cover (6) is flush with the end face of the housing (1). The piston (2) is pushed against the bottom of the housing (1) by the action of the spring (3). The piston (2) has a scale line (21) to monitor the oil tank level. There are external threads on the outside of the housing (1) and internal threads on the filling fixture (10). The two are connected by threads. When filling, the filling fixture (10) is screwed into the housing (1). As the volume of oil in the pressurized oil tank increases, the piston (2) will gradually extend outward until the piston (2) hits the filling fixture (10) and the filling step is completed. The filling volume is controlled by controlling the depth of the filling fixture (10) screwed into the housing (1).

2. The booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, A seal (7) is provided between the piston (2) and the housing (1). The seal (7) adopts a combination of AQ seal + (2) side wear-resistant ring to achieve effective gas-liquid isolation.

3. The booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, A needle roller bearing (5) is placed between the end cap (6) and the spring seat (4) to reduce the resistance when the end cap (6) is screwed in, making it easier to adjust the end cap (6).

4. The booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, The piston (2) consists of two parts: a piston section (21) and a guide section (22). The piston section (21) is fitted with the housing (1) through a seal (7), and the guide section (22) is fitted with the end cap (6) with a clearance.

5. A booster tank for an electro-hydraulic actuator according to claim 4, characterized in that, The piston section (21) has a sealing groove (23) for installing a sealing ring, which cooperates with the housing (1); the guide section (22) has a scale line (24) for use with the end cap (6), and the oil tank level is determined by the scale line (24).

6. A booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, After filling with liquid, unscrew the filling fixture (10) from the housing (1). At this time, the back pressure of the booster tank is determined by the compression of the spring (3). If it is necessary to increase the back pressure of the system, screw the end cap (6) into the housing (1). If it is necessary to decrease the back pressure of the system, screw the end cap (6) out of the housing (1).

7. A booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, During operation, the volume of the actuator oil changes due to temperature changes and external leakage of the actuator. At this time, the piston (2) will move and the change in oil volume can be judged by the scale line (21) outside the piston rod extending from the end cap (6).

8. A booster tank for an electro-hydraulic actuator according to claim 1, characterized in that, The end cap (6) is annular, with a guide hole (41) in the middle and a connecting thread (42) on the outside. There are multiple circular holes (43) distributed in a circle on the annular end face. The end cap (6) is connected to the housing (1) by the thread and its screw-in depth is adjusted by the circular holes (43).

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