Rotary damper

Abstract

The rotary damper comprises a cylinder body and a piston shaft movably arranged on the cylinder body, and an upward moving guide inclined face is obliquely arranged on the inner side wall of the bottom of the cylinder body; the lower end part of the piston shaft is provided with a moving part and a piston provided with an oil passing hole, the lower end part of the moving part is provided with an upward moving pressing inclined surface matched with the upward moving guide inclined surface, and the upper end part of the moving part is propped against the piston; the piston shaft drives the moving part to rotate, and the upward-moving pressing inclined plane is matched with the upward-moving guide inclined plane, so that the moving part moves upwards along the upward-moving guide inclined plane, and the piston is driven to move upwards; damping oil in the cylinder body flows up and down through the oil passing hole, so that a damping effect is generated on the rotary motion of the piston shaft; the damping effect on the rotary motion can be directly realized by converting the rotary motion mode and the axial motion mode without additionally installing accessories; the damper application cost is reduced, and the product production difficulty is effectively reduced; the rotary damper is simple in structure and low in production cost.

Description

Technical Field

[0001] This invention relates to the field of damper technology, and more specifically, to a rotary damper. Background Technology

[0002] A damper is a device that provides resistance to motion and reduces the energy of motion. Dampers enable products to achieve smooth mechanical movement, improve product quality and lifespan, and are widely used in small flip covers, gift boxes, car window safety handles, floor sockets, hinges, etc. They can effectively reduce the noise generated during product use. When dampers are applied to hinges installed on doors, they can prevent the hinges from being opened violently or closed violently due to the door's own weight. By installing a damper at the rotating connection of the hinge, it can be opened or closed slowly.

[0003] A damper typically consists of a cylinder and a piston shaft with a piston. The piston shaft drives the piston to move up and down within the cylinder, and the damping oil within the cylinder resists the movement of the piston shaft, thus achieving a damping effect. In other words, the damping effect is generated through the axial movement of the piston shaft. However, in practical applications such as the aforementioned door hinges, which involve rotational motion, existing dampers cannot be used directly. It is necessary to use installation accessories to convert the rotational motion of the door hinges to drive the damper's piston shaft to move axially, thereby achieving the damping purpose. This increases the actual application cost of the damper and also increases the manufacturing difficulty of products such as damping hinges. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a rotary damper.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A rotary damper includes a cylinder and a piston shaft movably mounted on the cylinder, wherein the inner sidewall at the bottom of the cylinder is provided with an upward guide slope.

[0007] The lower end of the piston shaft is provided with a movable part and a piston with an oil passage hole. The lower end of the movable part is provided with an upward pressing slope that cooperates with the upward guide slope, and its upper end abuts against the piston.

[0008] The upper end of the piston shaft is provided with a reset structure to drive the piston to reset.

[0009] The piston shaft drives the moving part to rotate. The upward pressing inclined surface cooperates with the upward guiding inclined surface, causing the moving part to move upward along the upward guiding inclined surface, thus driving the piston to move upward. The piston shaft drives the moving part to rotate in the opposite direction. The reset structure presses down the piston, driving the moving part to move downward along the upward guiding inclined surface, thus achieving reset.

[0010] The present invention further comprises: the reset structure being a reset spring, the lower end of which abuts against the piston, and the upper end of which abuts against the cylinder cover at the upper end of the cylinder body.

[0011] The present invention further comprises: the reset structure including a reset guide portion at the upper end of the piston and a reset clamping member placed at the upper end of the piston; the reset guide portion is inclinedly provided with a downward guide slope; the lower end of the reset clamping member is provided with a downward clamping slope; the downward guide slope and the downward clamping slope are arranged opposite to each other.

[0012] The piston rotates in the opposite direction, driving the downward pressing inclined surface to press down on the downward guiding inclined surface, which in turn drives the piston to move the moving part downward.

[0013] The present invention further comprises: a plurality of positioning protrusions are provided at intervals on the inner sidewall of the cylinder, and a plurality of positioning planes that cooperate with the positioning protrusions are provided on the sidewall of the reset clamping member;

[0014] The positioning protrusion cooperates with the positioning plane to prevent the reset clamping component from rotating relative to the cylinder.

[0015] The present invention further comprises: an annular groove for installing a sealing ring is provided on the outer side wall of the piston, and the sealing ring is movably disposed in the annular groove;

[0016] The piston has several lower oil grooves on its outer side wall at the lower end, and the lower oil grooves are connected to the lower cavity of the cylinder.

[0017] The bottom wall of the annular groove is provided with a plurality of upper oil passage grooves. The upper oil passage grooves extend upward through the upper end of the piston and are connected to the upper cavity of the cylinder. The plurality of upper oil passage grooves are provided in a one-to-one correspondence with the plurality of lower oil passage grooves.

[0018] When the piston moves outward, the damping oil in the cylinder flows from the upper cavity into the lower cavity, causing the sealing ring to adhere tightly to the bottom wall of the annular groove and seal the lower oil groove.

[0019] As the piston moves inward, the damping oil flows from the lower cavity into the upper cavity, causing the sealing ring to adhere tightly to the upper wall of the annular groove, thus connecting the upper oil groove with the lower oil groove.

[0020] The present invention further comprises: an annular oil passage provided on the lower end face of the piston, one end of the annular oil passage being connected to an oil passage hole, and the other end being connected to the lower cavity of the cylinder.

[0021] The present invention further comprises: the lower end of the piston shaft is a flat structure, and a flat hole is provided in the middle of the moving part and the piston; wherein the moving part and the piston are sequentially sleeved on the lower end of the piston shaft from bottom to top.

[0022] The present invention further comprises: the movable component and the piston are axially movable at the lower end of the piston shaft, so that when the piston shaft drives the movable component and the piston to rotate, the movable component and the piston move up and down relative to the piston shaft;

[0023] Alternatively, the movable component and piston can be fixedly mounted at the lower end of the piston shaft, so that when the piston shaft drives the movable component and piston to rotate, the piston shaft moves up and down in the cylinder along with the movable component and piston.

[0024] The present invention further provides that a pair of fluid grooves are provided opposite to each other on the inner side wall of the upper end of the cylinder. When the piston moves upward to the position of the fluid grooves, the upper cavity and the lower cavity of the cylinder are connected through the fluid grooves.

[0025] The present invention further includes a Y-shaped sealing ring at the opening of the cylinder body, the Y-shaped sealing ring being positioned below the cylinder body cover.

[0026] The beneficial effects of this invention are as follows: The inner wall of the cylinder bottom of the rotary damper is inclined with an upward guide slope; a movable component and a piston with an oil passage hole are provided at the lower end of the piston shaft; wherein the lower end of the movable component is provided with an upward pressing slope that cooperates with the upward guide slope, and its upper end abuts against the piston; when an external force drives the piston shaft to rotate, the piston shaft drives the movable component and the piston to rotate, and the upward pressing slope at the lower end of the movable component will cooperate with the upward guide slope. Under the pressure of the upward guide slope, the movable component moves upward along the upward guide slope, driving the piston to move upward; the damping oil in the cylinder flows up and down through the oil passage hole, thereby generating a damping effect on the rotational motion of the piston shaft; no additional accessories are required, and the damping effect on the rotational motion can be directly achieved by converting the rotational motion mode and the axial motion mode; the operating cost of the damper is reduced, and the production difficulty of the product is effectively reduced; at the same time, the rotary damper has a simple structure and low production cost. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of a rotary damper according to the present invention;

[0028] Figure 2 This is an exploded view of Example 1;

[0029] Figure 3 Cross-sectional view of the internal structure of Example 1 Figure 1 ;

[0030] Figure 4 Cross-sectional view of the internal structure of Example 1 Figure 2 ;

[0031] Figure 5 This is a schematic diagram of the internal structure of the cylinder block in Example 1;

[0032] Figure 6This is a diagram showing the moving part and the piston mating with the piston shaft in Example 1;

[0033] Figure 7 This is a schematic diagram of the piston structure in Example 1;

[0034] Figure 8 This is a bottom view of the piston in Example 1;

[0035] Figure 9 This is a top view of the piston in Example 1;

[0036] Figure 10 Exploded view of Example 2;

[0037] Figure 11 Cross-sectional view of Example 2;

[0038] Figure 12 Internal structure diagram of Example 2;

[0039] Figure 13 A schematic diagram of the cylinder block in Example 2;

[0040] Figure 14 This is a schematic diagram of the piston structure in Example 2;

[0041] Figure 15 This is a bottom view of the piston in Example 2;

[0042] Figure 16 This is a top view of the piston in Example 2;

[0043] Explanation of reference numerals in the attached drawings: 1. Cylinder body; 11. Upward guide ramp; 12. Cylinder body cover; 13. Positioning protrusion; 14. Fluid groove; 15. Y-type sealing ring; 2. Piston shaft; 21. Flat structure; 3. Moving part; 31. Upward pressing ramp; 4. Piston; 41. Oil passage hole; 42. Downward guide ramp; 43. Sealing ring; 44. Annular groove; 441. Upper oil passage groove; 45. Lower oil passage groove; 46. Annular oil passage; 5. Return spring; 6. Return pressing part; 61. Downward pressing ramp; 62. Positioning plane. Detailed Implementation

[0044] See attached document Figures 1 to 16 The present invention provides a more detailed description of a rotary damper and a floor spring.

[0045] Example 1: A rotary damper includes a cylinder 1 and a piston shaft 2 movably disposed on the cylinder 1, wherein the inner sidewall of the bottom of the cylinder 1 is provided with an upward guide slope 11.

[0046] The lower end of the piston shaft 2 is provided with a movable part 3 and a piston 4 with an oil passage hole 41. The lower end of the movable part 3 is provided with an upward pressing inclined surface 31 that cooperates with the upward guide inclined surface 11, and its upper end abuts against the piston 4. There is a gap between the movable part 3 and the inner wall of the cylinder body 1, so that the damping oil in the lower cavity of the cylinder body 1 can directly pass through the movable part 3.

[0047] The upper end of the piston shaft 2 is provided with a return spring 5 that drives the piston 4 to return to its original position. The lower end of the return spring 5 abuts against the piston 4, and its upper end abuts against the cylinder cover 12 at the upper end of the cylinder body 1.

[0048] The piston shaft 2 drives the moving part 3 to rotate. The upward pressing inclined surface 31 cooperates with the upward guiding inclined surface 11, causing the moving part 3 to move upward along the upward guiding inclined surface 11, thus driving the piston 4 to move upward. The piston shaft 2 drives the moving part 3 to rotate in the opposite direction. The reset structure presses down the piston 4, driving the moving part 3 to move downward along the upward guiding inclined surface 11, thus achieving reset.

[0049] When an external force drives the piston shaft 2 to rotate, the piston shaft 2 drives the moving part 3 and the piston 4 to rotate. The upward pressing slope 31 at the lower end of the moving part 3 will cooperate with the upward guiding slope 11. Under the pressure of the upward guiding slope 11, the moving part 3 moves upward along the upward guiding slope 11, driving the piston 4 to move upward. This causes the damping oil in the cylinder 1 to flow up and down through the oil passage 41, thereby generating a damping effect on the rotational motion of the piston shaft 2. No additional accessories are required. By switching between the rotational motion mode and the axial motion mode, the damping effect on the rotational motion can be directly achieved. This reduces the operating cost of the damper and effectively reduces the production difficulty of the product. At the same time, the rotary damper has a simple structure and low production cost.

[0050] The piston 4 has an annular groove 44 on its outer side wall for installing a sealing ring 43, and the sealing ring 43 is movably disposed in the annular groove 44. The piston 4 has a plurality of lower oil passage grooves 45 on its lower outer side wall, and the lower oil passage grooves 45 are connected to the lower cavity of the cylinder 1. The annular groove 44 has a plurality of upper oil passage grooves 441 on its bottom wall, and the upper oil passage grooves 441 extend upward through the upper end of the piston 4 and are connected to the upper cavity of the cylinder 1. The plurality of upper oil passage grooves 441 are provided in a one-to-one correspondence with the plurality of lower oil passage grooves 45.

[0051] When the piston 4 moves outward, the damping oil in the cylinder 1 flows from the upper cavity into the lower cavity, driving the sealing ring 43 to move downward, so that the sealing ring 43 is pressed against the bottom wall of the annular groove 44 to seal the lower oil passage 45; thus, the lower oil passage 45 is blocked from the upper oil passage 441, so that the damping oil in the upper cavity cannot enter the lower cavity through the lower oil passage 45; it can only flow through a single oil passage hole 41, which produces a large damping effect on the rotation of the piston shaft 2;

[0052] When the piston 4 moves inward, the damping oil flows from the lower cavity into the upper cavity, causing the sealing ring 43 to adhere tightly to the upper wall of the annular groove 44, thus connecting the upper oil passage 441 with the lower oil passage 45. This allows the damping oil in the lower cavity to directly enter the upper cavity through the lower oil passage 45 and the upper oil passage 441, thereby expanding the oil passage between the upper and lower cavities and reducing the damping effect of the damper. In other words, this rotary damper is a unidirectional damper.

[0053] The piston 4 has an annular oil passage 46 on its lower end face. One end of the annular oil passage 46 is connected to the oil passage 41, and the other end is connected to the lower cavity of the cylinder 1. That is, the damping oil in the upper cavity and the lower cavity flows through the annular oil passage 46 and the oil passage 41.

[0054] The lower end of the piston shaft 2 is a flat structure 21, and the moving part 3 and the piston 4 are both provided with flat holes in the middle; the moving part 3 and the piston 4 are sequentially sleeved on the lower end of the piston shaft 2 from bottom to top.

[0055] The movable component 3 and piston 4 are axially movable at the lower end of the piston shaft 2, so that when the piston shaft 2 drives the movable component 3 and piston 4 to rotate, the movable component 3 and piston 4 move up and down relative to the piston shaft 2; even if the piston shaft 2 only achieves rotational motion.

[0056] Alternatively, the movable part 3 and the piston 4 can be fixedly installed at the lower end of the piston shaft 2, so that when the piston shaft 2 drives the movable part 3 and the piston 4 to rotate, the piston shaft 2 moves up and down with the movable part 3 and the piston 4 in the cylinder body 1; that is, the piston shaft 2 performs both rotational motion and axial movement; so that the rotary damper can be used in different products.

[0057] The cylinder 1 has a pair of fluid grooves 14 arranged opposite each other on the inner side wall at the upper end. When the piston 4 moves upward to the position of the fluid groove 14, the upper cavity and the lower cavity of the cylinder 1 are connected through the fluid groove 14. Even if the piston shaft 2 rotates to a certain angle and the piston 4 moves to the position of the fluid groove 14, the rotation damper instantly loses its damping effect.

[0058] A Y-shaped sealing ring 15 is provided at the opening of the cylinder body 1. The Y-shaped sealing ring 15 is placed below the cylinder body cover 12. The upper end of the piston shaft 2 passes through the Y-shaped sealing ring 15 and the cylinder body cover 12. The Y-shaped sealing ring 15 seals the upper end of the cylinder body 1, thereby improving the sealing effect of the damper.

[0059] Example 2: A rotary damper includes a cylinder 1 and a piston shaft 2 movably disposed on the cylinder 1, wherein the inner sidewall of the bottom of the cylinder 1 is provided with an upward guide slope 11.

[0060] The lower end of the piston shaft 2 is provided with a movable part 3 and a piston 4 with an oil passage hole 41. The lower end of the movable part 3 is provided with an upward pressing inclined surface 31 that cooperates with the upward guide inclined surface 11, and its upper end abuts against the piston 4. There is a gap between the movable part 3 and the inner wall of the cylinder body 1, so that the damping oil in the lower cavity of the cylinder body 1 can directly pass through the movable part 3.

[0061] The upper end of the piston shaft 2 is provided with a reset structure for driving the piston 4 to reset. The reset structure includes a reset guide part at the upper end of the piston 4 and a reset clamping member 6 placed at the upper end of the piston 4. The reset guide part is inclined with a downward guide slope 42, and the lower end of the reset clamping member 6 is provided with a downward clamping slope 61. The downward guide slope 42 and the downward clamping slope 61 are arranged opposite to each other.

[0062] The piston 4 rotates in the opposite direction, driving the downward pressing inclined surface 61 to press down on the downward guiding inclined surface 42, driving the piston 4 to move the moving part 3 downward; driving the piston 4 and the moving part 3 to reset themselves.

[0063] The piston shaft 2 drives the moving part 3 to rotate. The upward pressing inclined surface 31 cooperates with the upward guiding inclined surface 11, causing the moving part 3 to move upward along the upward guiding inclined surface 11, thus driving the piston 4 to move upward. The piston shaft 2 drives the moving part 3 to rotate in the opposite direction. The reset structure presses down the piston 4, driving the moving part 3 to move downward along the upward guiding inclined surface 11, thus achieving reset.

[0064] When an external force drives the piston shaft 2 to rotate, the piston shaft 2 drives the moving part 3 and the piston 4 to rotate. The upward pressing slope 31 at the lower end of the moving part 3 will cooperate with the upward guiding slope 11. Under the pressure of the upward guiding slope 11, the moving part 3 moves upward along the upward guiding slope 11, driving the piston 4 to move upward. This causes the damping oil in the cylinder 1 to flow up and down through the oil passage 41, thereby generating a damping effect on the rotational motion of the piston shaft 2. No additional accessories are required. By switching between the rotational motion mode and the axial motion mode, the damping effect on the rotational motion can be directly achieved. This reduces the operating cost of the damper and effectively reduces the production difficulty of the product. At the same time, the rotary damper has a simple structure and low production cost.

[0065] The inner sidewall of the cylinder 1 is provided with a plurality of positioning protrusions 13 at intervals, and the sidewall of the reset clamping member 6 is provided with a plurality of positioning planes 62 that cooperate with the positioning protrusions 13; the positioning protrusions 13 cooperate with the positioning planes 62 to prevent the reset clamping member 6 from rotating relative to the cylinder 1; thus improving the structural stability of the product.

[0066] The piston 4 has an annular groove 44 on its outer side wall for installing a sealing ring 43, and the sealing ring 43 is movably disposed in the annular groove 44. The piston 4 has a plurality of lower oil passage grooves 45 on its lower outer side wall, and the lower oil passage grooves 45 are connected to the lower cavity of the cylinder 1. The annular groove 44 has a plurality of upper oil passage grooves 441 on its bottom wall, and the upper oil passage grooves 441 extend upward through the upper end of the piston 4 and are connected to the upper cavity of the cylinder 1. The plurality of upper oil passage grooves 441 are provided in a one-to-one correspondence with the plurality of lower oil passage grooves 45.

[0067] When the piston 4 moves outward, the damping oil in the cylinder 1 flows from the upper cavity into the lower cavity, driving the sealing ring 43 to move downward, so that the sealing ring 43 is pressed against the bottom wall of the annular groove 44 to seal the lower oil passage 45; thus, the lower oil passage 45 is blocked from the upper oil passage 441, so that the damping oil in the upper cavity cannot enter the lower cavity through the lower oil passage 45; it can only flow through a single oil passage hole 41, which produces a large damping effect on the rotation of the piston shaft 2;

[0068] When the piston 4 moves inward, the damping oil flows from the lower cavity into the upper cavity, causing the sealing ring 43 to adhere tightly to the upper wall of the annular groove 44, thus connecting the upper oil passage 441 with the lower oil passage 45. This allows the damping oil in the lower cavity to directly enter the upper cavity through the lower oil passage 45 and the upper oil passage 441, thereby expanding the oil passage between the upper and lower cavities and reducing the damping effect of the damper. In other words, this rotary damper is a unidirectional damper.

[0069] The piston 4 has an annular oil passage 46 on its lower end face. One end of the annular oil passage 46 is connected to the oil passage 41, and the other end is connected to the lower cavity of the cylinder 1. That is, the damping oil in the upper cavity and the lower cavity flows through the annular oil passage 46 and the oil passage 41.

[0070] The lower end of the piston shaft 2 is a flat structure 21, and the moving part 3 and the piston 4 are both provided with flat holes in the middle; the moving part 3 and the piston 4 are sequentially sleeved on the lower end of the piston shaft 2 from bottom to top.

[0071] The movable component 3 and piston 4 are axially movable at the lower end of the piston shaft 2, so that when the piston shaft 2 drives the movable component 3 and piston 4 to rotate, the movable component 3 and piston 4 move up and down relative to the piston shaft 2; even if the piston shaft 2 only achieves rotational motion.

[0072] Alternatively, the movable part 3 and the piston 4 can be fixedly installed at the lower end of the piston shaft 2, so that when the piston shaft 2 drives the movable part 3 and the piston 4 to rotate, the piston shaft 2 moves up and down with the movable part 3 and the piston 4 in the cylinder body 1; that is, the piston shaft 2 performs both rotational motion and axial movement; so that the rotary damper can be used in different products.

[0073] The cylinder 1 has a pair of fluid grooves 14 arranged opposite each other on the inner side wall at the upper end. When the piston 4 moves upward to the position of the fluid groove 14, the upper cavity and the lower cavity of the cylinder 1 are connected through the fluid groove 14. Even if the piston shaft 2 rotates to a certain angle and the piston 4 moves to the position of the fluid groove 14, the rotation damper instantly loses its damping effect.

[0074] A Y-shaped sealing ring 15 is provided at the opening of the cylinder body 1. The Y-shaped sealing ring 15 is placed below the cylinder body cover 12. The upper end of the piston shaft 2 passes through the Y-shaped sealing ring 15 and the cylinder body cover 12. The Y-shaped sealing ring 15 seals the upper end of the cylinder body 1, thereby improving the sealing effect of the damper.

[0075] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A rotating damper, characterized in that: It includes a cylinder body and a piston shaft movably mounted on the cylinder body, wherein the inner sidewall at the bottom of the cylinder body is provided with an upward guide slope. The lower end of the piston shaft is provided with a movable part and a piston with an oil passage hole. The lower end of the movable part is provided with an upward pressing slope that cooperates with the upward guide slope, and its upper end abuts against the piston. The upper end of the piston shaft is provided with a reset structure to drive the piston to reset. The piston shaft drives the moving part to rotate. The upward pressing inclined surface cooperates with the upward guiding inclined surface, causing the moving part to move upward along the upward guiding inclined surface, thus driving the piston to move upward. The piston shaft drives the moving part to rotate in the opposite direction. The reset structure presses down the piston, driving the moving part to move downward along the upward guiding inclined surface, thus achieving reset.

2. The rotary damper according to claim 1, characterized in that: The reset structure is a reset spring, with its lower end abutting against the piston and its upper end abutting against the cylinder cover at the upper end of the cylinder body.

3. A rotary damper according to claim 1, characterized in that: The reset structure includes a reset guide portion at the upper end of the piston and a reset clamping member placed at the upper end of the piston. The reset guide portion is inclined with a downward guide slope, and the lower end of the reset clamping member is provided with a downward clamping slope. The downward guide slope and the downward clamping slope are arranged opposite to each other. The piston rotates in the opposite direction, driving the downward pressing inclined surface to press down on the downward guiding inclined surface, which in turn drives the piston to move the moving part downward.

4. A rotary damper according to claim 3, characterized in that: The inner sidewall of the cylinder is provided with a number of positioning protrusions at intervals, and the sidewall of the reset clamping member is provided with a number of positioning planes that cooperate with the positioning protrusions. The positioning protrusion cooperates with the positioning plane to prevent the reset clamping component from rotating relative to the cylinder.

5. A rotary damper according to claim 1, 2, 3, or 4, characterized in that: The piston has an annular groove on its outer side wall for installing a sealing ring, and the sealing ring is movably disposed in the annular groove. The piston has several lower oil grooves on its outer side wall at the lower end, and the lower oil grooves are connected to the lower cavity of the cylinder. The bottom wall of the annular groove is provided with a plurality of upper oil passage grooves. The upper oil passage grooves extend upward through the upper end of the piston and are connected to the upper cavity of the cylinder. The plurality of upper oil passage grooves are provided in a one-to-one correspondence with the plurality of lower oil passage grooves. When the piston moves outward, the damping oil in the cylinder flows from the upper cavity into the lower cavity, causing the sealing ring to adhere tightly to the bottom wall of the annular groove and seal the lower oil groove. As the piston moves inward, the damping oil flows from the lower cavity into the upper cavity, causing the sealing ring to adhere tightly to the upper wall of the annular groove, thus connecting the upper oil groove with the lower oil groove.

6. A rotary damper according to claim 5, characterized in that: The piston has an annular oil passage on its lower end face. One end of the annular oil passage is connected to an oil passage hole, and the other end is connected to the lower cavity of the cylinder.

7. A rotary damper according to claim 5, characterized in that: The lower end of the piston shaft has a flat structure, and a flat hole is provided in the middle of the moving part and the piston; wherein the moving part and the piston are sequentially sleeved on the lower end of the piston shaft from bottom to top.

8. A rotary damper according to claim 7, characterized in that: The movable component and piston are axially movable at the lower end of the piston shaft, so that when the piston shaft drives the movable component and piston to rotate, the movable component and piston move up and down relative to the piston shaft. Alternatively, the movable component and piston can be fixedly mounted at the lower end of the piston shaft, so that when the piston shaft drives the movable component and piston to rotate, the piston shaft moves up and down in the cylinder along with the movable component and piston.

9. A rotary damper according to claim 2, characterized in that: A pair of fluid grooves are arranged opposite each other on the inner side wall of the upper end of the cylinder. When the piston moves upward to the position of the fluid grooves, the upper cavity and the lower cavity of the cylinder are connected through the fluid grooves.

10. A rotary damper according to claim 1, 2, 3, or 4, characterized in that: The cylinder opening is provided with a Y-shaped sealing ring located below the cylinder cover.

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