Double-cylinder-diameter hydraulic cylinder

Abstract

The utility model discloses a double-cylinder-diameter hydraulic cylinder which comprises a cylinder body and a first piston assembled on the cylinder body in a sealing mode, and a first oil cavity is formed between the cylinder body and the first piston. A groove extending downwards in the axial direction is formed in the top end of the first piston; the second piston is assembled in the first piston groove in a sealed mode, and a second oil cavity is formed between the first piston groove and the second piston; the top face of the second piston can be flush with the top face of the first piston. The first oil cavity is an annular flow channel, and the second oil cavity is an expanded flow channel. The double-piston structure composed of the first piston and the second piston is adopted, the second piston with the small cylinder diameter is used when small rolling force needs to be output, the first piston and the second piston are combined for use when large rolling force needs to be output, and therefore the second piston is used when the small rolling force needs to be output, and the pressure acting area is reduced; therefore, pressure fluctuation is reduced, more stable hydraulic output can be provided, equipment precision is effectively improved, and meanwhile the requirement for large rolling force can be met.

Description

Technical Field

[0001] The utility model relates to a hydraulic cylinder used in pole piece rolling, in particular to a hydraulic cylinder with double cylinder diameters. Background Art

[0002] Pole piece rolling is an important link in the production process of lithium-ion batteries, which can enhance the bonding strength between the active material and the foil to prevent peeling during electrolyte immersion and battery use, and can also improve the energy density of lithium batteries. To ensure the thickness consistency of the rolled pole piece, the rolling force needs to be kept stable. Since the rolling force of the rolling mill comes from the hydraulic cylinder, the accuracy of the hydraulic cylinder is crucial for pole piece rolling.

[0003] Traditionally, a hydraulic cylinder with a single cylinder diameter is used. The control accuracy of the hydraulic pressure is determined by the hydraulic control valve. As is well known, pressure is equal to pressure intensity multiplied by the acting area. Therefore, after the hydraulic control valve is selected, the pressure fluctuation of the hydraulic cylinder is positively correlated with the piston area. So, the larger the cylinder diameter of the hydraulic cylinder, the greater the deviation value of the hydraulic cylinder output force. In order to meet the different rolling force requirements during rolling, the cylinder diameter of the hydraulic cylinder of the rolling mill is usually selected to be relatively large, which results in obvious output force fluctuations of the hydraulic cylinder when small rolling force is required for rolling. Summary of the Utility Model

[0004] To solve the above deficiencies in the prior art, the utility model aims to provide a hydraulic cylinder with double cylinder diameters to improve the equipment accuracy when outputting medium and small pressures.

[0005] To achieve the above object, the technical solution adopted by the utility model is as follows: a hydraulic cylinder with double cylinder diameters includes a cylinder body and a first piston hermetically assembled on the cylinder body. A first oil chamber is formed between the cylinder body and the first piston; a groove extending axially downward is provided at the top end of the first piston.

[0006] It further includes a second piston hermetically assembled in the groove of the first piston. A second oil chamber is formed between the groove of the first piston and the second piston.

[0007] The top surface of the second piston can be flush with the top surface of the first piston.

[0008] The first oil chamber is an annular flow channel, and the second oil chamber is an extended flow channel.

[0009] As a limitation of the utility model, a guide post extending axially upward is provided at the bottom inside the cylinder body, and a guide groove adapted to the guide post is provided at the bottom of the first piston.

[0010] As a further limitation of the utility model, the guide groove communicates with the groove, and the diameter of the guide groove is smaller than the diameter of the groove.

[0011] As another limitation of the utility model, heat dissipation fins are provided on the outer side wall of the cylinder body.

[0012] As a further limitation of the present utility model, the contact surface between the first piston and the cylinder block is provided with a PTFE coating; the contact surface between the second piston and the groove of the first piston is provided with a PTFE coating.

[0013] Due to the adoption of the above technical solutions, compared with the prior art, the beneficial effects achieved by the present utility model are as follows:

[0014] (1) The present utility model proposes a brand-new hydraulic cylinder with double cylinder diameters. Different from the single-piston structure of conventional hydraulic cylinders, it adopts a double-piston structure composed of a first piston and a second piston. The double pistons can be used separately or in combination. When a small rolling force needs to be output, the second piston with a small cylinder diameter is used; when a large rolling force needs to be output, the first piston and the second piston are used in combination. In this way, when the small rolling force is used, the second piston reduces the pressure acting area (small cylinder diameter), thereby reducing the pressure fluctuation, enabling a more stable hydraulic output to be provided, effectively improving the equipment accuracy, and at the same time meeting the need for a large rolling force.

[0015] (2) The present utility model designs the first oil cavity as an annular flow channel, which can increase the contact area with the cylinder block, contribute to heat dissipation. In addition, the annular flow channel design can provide a more uniform flow path, reduce dead zones and eddies, ensure the uniform distribution of the liquid in the hydraulic cylinder, and at the same time the resistance during fluid flow is relatively small, which helps to reduce the pressure loss; the present utility model designs the second oil cavity as an extended flow channel, which can effectively reduce the fluid flow velocity, reduce the turbulence phenomenon of the fluid, improve the working stability, and further improve the equipment accuracy.

[0016] (3) In the present utility model, the guide post and guide groove structure provided between the cylinder block and the first piston can ensure the linear movement of the first piston in the cylinder block, reducing lateral friction and wear.

[0017] (4) In the present utility model, heat dissipation fins are provided on the outer side wall of the cylinder block, which can effectively reduce the temperature of the hydraulic oil, prevent performance degradation due to overheating, maintain an appropriate working temperature, contribute to improving the working stability of the hydraulic system, reduce the probability of faults occurring, and extend the service life of the hydraulic system and its components.

[0018] (5) In the present utility model, a PTFE coating is applied on the contact surfaces of the first piston and the second piston, which can effectively reduce friction, reduce wear, extend the service life, improve the sealing performance, and reduce leakage. Description of the Drawings

[0019] The following further describes the present utility model in more detail with reference to the drawings and specific embodiments.

[0020] Figure 1 It is a sectional view of the structural relationship of the embodiment of the present utility model;

[0021] Figure 2 This is a structural relationship cross-sectional view of the first piston in the embodiment of the present utility model;

[0022] In the figure: 1. Cylinder block; 2. First piston; 3. Second piston; 4. Guide post; 5. Guide groove; 6. Groove; 7. First oil chamber; 8. Second oil chamber; 9. First oil inlet; 10. Second oil inlet. Specific embodiments

[0023] The following is a description of the preferred embodiments of the present utility model with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only for the purpose of illustrating and understanding the present utility model, and are not used to limit the present utility model.

[0024] This embodiment discloses a double-bore hydraulic cylinder, which includes a cylinder block 1, a first piston 2 and a second piston 3. As Figure 1 shown, the cylinder block 1 is of a cylindrical structure, and a guide post 4 extending axially upward is provided at the middle position of its bottom, and heat dissipation fins (not shown in the figure) are provided on the outer side wall. In this embodiment, the heat dissipation fins are made of aluminum alloy material; as Figure 2 shown, the first piston 2 is of a columnar structure, and a guide groove 5 extending axially upward is provided at its bottom. The guide groove 5 is adapted to the guide post 4. A groove 6 extending axially downward is provided at the top of the first piston 2. In this embodiment, the groove 6 communicates with the guide groove 5, and the diameter of the groove 6 is larger than the diameter of the guide groove 5; the second piston 3 is of a columnar structure adapted to the groove 6.

[0025] Furthermore, the first piston 2 is hermetically assembled on the cylinder block 1 through a conventional sealing member (such as a sealing ring), and the guide groove 5 cooperates with the guide post 4 (a sealing member is also provided between the guide groove 5 and the guide post 4). The cylinder block 1 serves as the cylinder barrel of the first piston 2, and a first oil chamber 7 is formed therebetween. As Figure 1 shown, the first oil chamber 7 is arranged around the guide post 4 to form an annular flow passage. The first oil inlet 9 and the first oil return port communicating with the first oil chamber 7 are both opened on the cylinder block 1, and the first oil inlet 9, the first oil return port and the first oil chamber 7 are at the same horizontal height.

[0026] The second piston 3 is hermetically assembled in the groove 6 of the first piston 2 through a conventional sealing member (such as a sealing ring). The first piston 2 serves as the cylinder barrel of the second piston 3, and a second oil chamber 8 is formed therebetween. As Figure 1 shown, the second oil chamber 8 is an extended flow passage, which is an inverted cone in this embodiment. The second oil inlet 10 and the second oil return port communicating with the second oil chamber 8 are also both opened on the cylinder block 1. The second oil inlet 10 and the second oil return port are communicated with the second oil chamber 8 through a passage obliquely arranged on the cylinder block 1.

[0027] It should be noted that when the second piston 3 is not ejected, the top surface of the second piston 3 is flush with the top surface of the first piston 2.

[0028] In order to reduce friction and improve the sealing performance, in this embodiment, PTFE coatings are provided on the contact surfaces between the first piston 2 and the cylinder block 1 and between the second piston 3 and the groove 6 of the first piston 2.

[0029] When this embodiment is applied to a roller press, the hydraulic output has three levels: large, medium, and small, and the corresponding pressure fluctuations are also divided into three levels: large, medium, and small:

[0030] 1. Working state with small rolling force (small level): Oil enters the second oil chamber 8, and the second piston 3 is pushed upward by the hydraulic pressure to apply force to the roller.

[0031] 2. Working state with medium rolling force (medium level): Oil enters the first oil chamber 7, and the first piston 2 is subjected to the hydraulic pressure, driving the second piston 3 upward to apply force to the roller.

[0032] 3. Working state with large rolling force (large level): Oil enters the first oil chamber 7 and the second oil chamber 8 simultaneously, and the first piston 2 and the second piston 3 are simultaneously pushed upward by the hydraulic pressure, and the force applied to the roller is the sum of the two.

[0033] What is disclosed in this embodiment is only a double-piston structure, and a multi-piston structure can also be designed according to this principle.

[0034] It should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions recorded in the above embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A double-bore hydraulic cylinder, characterized in that: It includes a cylinder block and a first piston hermetically assembled on the cylinder block, and a first oil chamber is formed between the cylinder block and the first piston; a groove extending axially downward is provided at the top end of the first piston; It further includes a second piston hermetically assembled in the groove of the first piston, and a second oil chamber is formed between the groove of the first piston and the second piston; The top surface of the second piston can be flush with the top surface of the first piston; The first oil chamber is an annular flow channel, and the second oil chamber is an extended flow channel.

2. A double-bore hydraulic cylinder according to claim 1, characterized in that: A guide post extending axially upward is provided at the bottom inside the cylinder block, and a guide groove adapted to the guide post is provided at the bottom of the first piston.

3. A double-bore hydraulic cylinder according to claim 2, wherein: The guide groove communicates with the groove, and the diameter of the guide groove is smaller than that of the groove.

4. A double-bore hydraulic cylinder according to any one of claims 1-3, characterized in that: Heat dissipation fins are provided on the outer side wall of the cylinder block.

5. A double-bore hydraulic cylinder according to claim 4, characterized in that: A PTFE coating is provided on the contact surface between the first piston and the cylinder block; a PTFE coating is provided on the contact surface between the second piston and the groove of the first piston.

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