Hydraulic spring hinge for narrow door

Abstract

The utility model provides a hydraulic spring hinge for a narrow door, which comprises a slender outer shell, a hydraulic cylinder body and a spring, the hydraulic cylinder body is slidably mounted in the outer shell, the spring is abutted between the hydraulic cylinder body and the outer shell, and a cylindrical groove body is arranged in the outer shell in an extending manner along the length direction of the outer shell. The hydraulic cylinder body and the spring are coaxially arranged in the cylindrical groove body; a cam shaft is inserted in the side, located on the hydraulic cylinder body, of the outer shell, and the hydraulic cylinder body abuts against the outer wall of the cam shaft. An auxiliary hydraulic cylinder body is installed in the outer shell in a sliding mode and coaxially arranged in the cylindrical groove body. The auxiliary hydraulic cylinder body and the hydraulic cylinder body are arranged on the two sides of the cam shaft correspondingly. The auxiliary hydraulic cylinder body is used for providing hydraulic buffering when the auxiliary hydraulic cylinder body is subjected to homonymous external force in the door closing process. According to the hydraulic spring hinge for the narrow door, the defect that an existing hydraulic hinge is not suitable for installation of the narrow door due to the fact that the overall size is large is overcome.

Description

Technical Field

[0001] This utility model relates to the field of hydraulic hinges, and in particular to a hydraulic spring hinge for narrow doors. Background Technology

[0002] Hinges, as components that connect two solid objects and allow them to rotate relative to each other, are widely used in doors, windows, furniture, and many other fields. As people's demands for quality of life and user experience increase, traditional hinges have gradually become insufficient in terms of functionality, leading to the development of hydraulic hinges. Hydraulic hinges, based on ordinary hinges, add a hydraulic damping system; the rotation speed of the pivot is controlled by the flow of hydraulic oil in a sealed cavity, achieving buffering and speed regulation functions for the opening and closing of doors, windows, or furniture doors.

[0003] Existing hydraulic damping hinges have complex hydraulic circuit structures and poor circuit reliability; moreover, they have many components, resulting in a large overall size, making them unsuitable for installation on narrow doors and inconvenient to install. Utility Model Content

[0004] (a) Technical problems to be solved

[0005] The problem to be solved by this utility model is to provide a hydraulic spring hinge for narrow doors, so as to overcome the defect that the existing hydraulic hinges are too large in overall size and are not suitable for installation on narrow doors.

[0006] (II) Technical Solution

[0007] To solve the aforementioned technical problem, this utility model provides a hydraulic spring hinge for narrow doors, comprising an elongated outer shell, a hydraulic cylinder slidably mounted within the outer shell, and a spring abutting between the hydraulic cylinder and the outer shell. A cylindrical groove extends along the length of the outer shell, and the hydraulic cylinder and the spring are coaxially arranged within the cylindrical groove. A camshaft is inserted into the outer shell on one side of the hydraulic cylinder, and the hydraulic cylinder abuts against the outer wall of the camshaft.

[0008] In some embodiments, an auxiliary hydraulic cylinder is slidably mounted inside the outer casing, and the auxiliary hydraulic cylinder is coaxially arranged inside the cylindrical groove; the auxiliary hydraulic cylinder and the hydraulic cylinder are respectively disposed on both sides of the camshaft, and the auxiliary hydraulic cylinder is used to provide hydraulic buffer when subjected to an external force in the same direction during the closing process.

[0009] In some embodiments, the upper end of the camshaft is provided with a limiting thin wall, the lower side of the limiting thin wall is formed with a widening groove, and the end of the hydraulic cylinder facing the camshaft is provided with a top block adapted to the widening groove.

[0010] In some embodiments, the outer circumferential wall of the camshaft is symmetrically and spaced apart with first cam walls, and a second cam wall is recessed between the two first cam walls. The auxiliary hydraulic cylinder is provided with a triangular top that abuts against the second cam wall. The first cam walls are used to push the hydraulic cylinder to slide, and the second cam wall is used to push the auxiliary hydraulic cylinder to slide.

[0011] In some embodiments, a damping assembly for generating a damping effect is installed inside the hydraulic cylinder. The damping assembly includes a piston rod, a piston, and a flow-retaining ring. One end of the piston rod is fixedly connected to the outer casing, and the other end is inserted into the hydraulic cylinder and fixed to the piston. The piston divides the internal cavity of the hydraulic cylinder into a left piston cavity and a right piston cavity. A pressure relief gap is formed between the outer wall of the piston and the inner wall of the hydraulic cylinder, and the pressure relief gap is used to connect the left piston cavity and the right piston cavity. The flow-retaining ring is slidably installed on the piston, and the flow-retaining ring is used to open and close the pressure relief gap. A return flow hole is provided inside the piston, and the right piston cavity is connected to the left piston cavity through the return flow hole.

[0012] In some embodiments, the damping assembly further includes a guide seat placed in the left cavity of the piston. The guide seat is fixed on the piston rod and abuts against the piston. A first through hole is symmetrically arranged in the guide seat, and a second through hole is symmetrically arranged at one end of the guide seat facing the piston. The left cavity of the piston communicates with the pressure relief gap through the first through hole and the second through hole in sequence. A guide ring is sleeved on the guide seat, and a notch is opened on the guide ring.

[0013] In some embodiments, the piston is provided with a plurality of pressure relief grooves at equal intervals in an annular shape, and the pressure relief gap is connected to the right chamber of the piston through the pressure relief grooves; one end of the piston is provided with an annular flange, and the annular flange and the hydraulic cylinder body form the pressure relief gap; the other end of the piston is fitted with a limiting ring, and the flow-blocking ring can slide between the annular flange and the limiting ring.

[0014] In some embodiments, L-shaped seats for covering the cylindrical groove are symmetrically installed at both ends of the outer casing. A camshaft hole is provided in the outer casing and arranged perpendicularly to the cylindrical groove. The camshaft is placed in the camshaft hole, and guide sleeves are installed on both sides of the camshaft hole. The camshaft is fixed on the base.

[0015] In some embodiments, a first end cap is fixed to one end of the hydraulic cylinder body away from the camshaft, a first spring seat is fixed inside the outer shell, one end of the spring is fitted onto the first end cap, and the other end is placed inside the first spring seat; a second end cap is fixed to one end of the auxiliary hydraulic cylinder body away from the camshaft, a second spring seat is fixed inside the outer shell, and an auxiliary spring is installed between the second end cap and the second spring seat.

[0016] (III) Beneficial Effects

[0017] This utility model provides a hydraulic spring hinge for narrow doors, featuring a long, narrow outer shell. The hydraulic cylinder, spring, and auxiliary hydraulic cylinder are all coaxially arranged within a cylindrical groove, resulting in a simple, compact, and small overall structure suitable for narrow door installations. It simplifies the hydraulic circuit structure, reducing the number of components. Through the cooperation of a guide seat, piston, and baffle ring, when the door is opened, the baffle ring slides and abuts against the limiting ring, opening the pressure relief gap. Most of the hydraulic oil in the left chamber of the piston sequentially enters the right chamber of the piston through the first through hole, the second through hole, the pressure relief gap, and the pressure relief groove. When the door is closed, the baffle ring slides and abuts against the annular flange, closing the pressure relief gap. The hydraulic oil in the right chamber of the piston flows back to the left chamber of the piston through a return flow hole. Due to the small size of the return flow hole, the return speed is slow, allowing the door to close slowly and smoothly with good damping effect. This overcomes the shortcomings of existing hydraulic hinges, which are too large for narrow door installations. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a perspective view of a hydraulic spring hinge for narrow doors according to the present invention;

[0020] Figure 2 This is an exploded view of a hydraulic spring hinge for narrow doors according to this utility model;

[0021] Figure 3 This is a cross-sectional view of a hydraulic spring hinge for narrow doors according to this utility model;

[0022] Figure 4 This is a perspective view of the connection between the hydraulic cylinder and the camshaft of a hydraulic spring hinge for a narrow door according to this utility model;

[0023] Figure 5 This is a perspective view of the hydraulic cylinder body, auxiliary hydraulic cylinder body, and camshaft connection of a hydraulic spring hinge for a narrow door according to this utility model.

[0024] Figure 6 This is a perspective view of a hydraulic spring hinge camshaft for narrow doors according to the present invention;

[0025] Figure 7 This is a schematic diagram of the internal structure of the hydraulic cylinder of a hydraulic spring hinge for narrow doors according to this utility model;

[0026] Figure 8 This is a perspective view of a hydraulic spring hinge damping assembly for narrow doors according to the present invention;

[0027] Figure 9 This is an exploded view of a hydraulic spring hinge damping assembly for narrow doors according to the present invention;

[0028] Figure 10 This is a schematic diagram of the internal structure of the auxiliary hydraulic cylinder of a hydraulic spring hinge for narrow doors according to this utility model;

[0029] Figure 11 This is an exploded view of the internal damping component of the auxiliary hydraulic cylinder of a hydraulic spring hinge for narrow doors according to this utility model.

[0030] The component names corresponding to the various reference numerals in the figure are as follows: 1. Outer shell; 101. Cylindrical groove; 102. Camshaft hole; 2. Hydraulic cylinder body; 201. Top block; 202. Left piston chamber; 203. Right piston chamber; 3. Spring; 4. Camshaft; 401. Limiting thin wall; 402. Widened groove; 403. First cam wall; 404. Second cam wall; 5. Auxiliary hydraulic cylinder body; 501. Triangular top head; 502. Left auxiliary piston chamber; 503. Right auxiliary piston chamber; 6. Piston rod; 7. Piston; 701. Pressure relief clearance; 702. Return flow hole; 703. Pressure relief groove; 704. Annular flange; 8. Baffle ring; 9. Guide seat; 901. First through hole; 902. Second through hole; 10. Guide ring; 1001. Notch; 11. Limiting ring; 12. L-shaped seat; 13. Base; 14. First end cap; 15. First spring seat; 16. Second end cap; 17. Second spring seat; 18. Auxiliary spring; 19. Guide sleeve; 20. Auxiliary piston rod; 21. Auxiliary piston; 211. Auxiliary pressure relief gap; 212. Auxiliary return flow hole; 213. Auxiliary pressure relief groove; 22. Auxiliary baffle ring; 23. Auxiliary limiting ring. Detailed Implementation

[0031] The present application will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0032] The following specific examples illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. This application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of this application. It should be noted that, in the absence of conflict, the following embodiments and features in the embodiments can be combined with each other. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0033] It should be noted that various aspects of embodiments within the scope of the appended claims are described below. It will be apparent that the aspects described herein can be embodied in a wide variety of forms, and any particular structure and / or function described herein is merely illustrative. Based on this application, those skilled in the art will understand that one aspect described herein can be implemented independently of any other aspect, and two or more of these aspects can be combined in various ways. For example, any number and aspects set forth herein can be used to implement the device and / or practice the method. Additionally, this device and / or method can be implemented using structures and / or functionalities other than one or more of the aspects set forth herein.

[0034] It should also be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of this application. The illustrations only show the components related to this application and are not drawn according to the number, shape and size of the components in actual implementation. In actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0035] Additionally, specific details are provided in the following description to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that practice can be carried out without these specific details.

[0036] The technical solutions provided by the various embodiments of this application are described below with reference to the accompanying drawings.

[0037] See Figures 1 to 11This utility model provides a hydraulic spring hinge for narrow doors, comprising an elongated outer shell 1, a hydraulic cylinder 2 slidably mounted within the outer shell 1, and a spring 3 abutting between the hydraulic cylinder 2 and the outer shell 1. The outer shell 1 is cuboid in shape, with a through cylindrical groove 101 extending along its length inside. The hydraulic cylinder 2 and spring 3 are coaxially arranged within the cylindrical groove 101. The hydraulic cylinder 2 is cylindrical and adapted to fit the cylindrical groove 101. A camshaft 4 is inserted into one side of the outer shell 1 located on the hydraulic cylinder 2, and the hydraulic cylinder 2 abuts against the outer wall of the camshaft 4. This layout results in a compact overall structure and small overall size, making it suitable for installation on narrow doors.

[0038] In some embodiments, such as Figure 2 and Figure 3 As shown, an auxiliary hydraulic cylinder 5 is slidably installed inside the outer casing 1. The auxiliary hydraulic cylinder 5 is coaxially arranged within a cylindrical groove 101, and is cylindrical in shape to fit the cylindrical groove 101. The auxiliary hydraulic cylinder 5 and the hydraulic cylinder 2 are respectively located on both sides of the camshaft 4. The auxiliary hydraulic cylinder 5 is configured to provide hydraulic buffering when the door suddenly reverses direction during opening or closing. This structural arrangement makes the overall structure more compact and reduces the overall size. In the prior art, when a sudden external force is applied in the same direction during the closing process, the door leaf accelerates to close, while the hydraulic cylinder slowly resets. This can easily cause the hydraulic cylinder to detach from the camshaft surface, thus losing its hydraulic damping effect and resulting in poor performance. Adding the auxiliary hydraulic cylinder 5 provides hydraulic buffering when a force is applied in the same direction during the closing process. The hydraulic cylinder 2 provides hydraulic damping force during closing.

[0039] In some embodiments, such as Figure 4 and Figure 5 As shown, a limiting thin wall 401 is provided at the upper end of the camshaft 4, and a widening groove 402 is formed on the lower side of the limiting thin wall 401. A top block 201 adapted to the widening groove 402 is provided at the end of the hydraulic cylinder body 2 facing the camshaft 4, and the top block 201 is placed inside the widening groove 402. With this structure, making the limiting thin wall 401 thinner can increase the thickness of the widening groove 402, thereby ensuring that the thickness of the top block 201 can be increased. When the overall size is reduced, it is still necessary to maintain the original hydraulic pressure and spring force. Increasing the thickness of the top block 201 can reduce wear and thus ensure service life.

[0040] In some embodiments, such as Figures 4 to 6 As shown, first cam walls 403 are symmetrically and spaced apart on the outer circumferential wall of the camshaft 4. A second cam wall 404 is formed concave between the two first cam walls 403. A triangular top 501 is provided on the auxiliary hydraulic cylinder 5 and abuts against the second cam wall 404. When the door is opened, the first cam wall 403 is used to push the hydraulic cylinder 2 to slide, and the second cam wall 404 is used to push the auxiliary hydraulic cylinder 5 to slide.

[0041] In some embodiments, such as Figures 7 to 9 As shown, a damping assembly for generating a damping effect is installed inside the hydraulic cylinder 2. The damping assembly includes a piston rod 6, a piston 7, and a baffle ring 8. One end of the piston rod 6 is fixedly connected to the outer casing 1, and the other end of the piston rod 6 is inserted into the hydraulic cylinder 2 and fixed to the piston 7. The piston 7 divides the inner cavity of the hydraulic cylinder 2 into a left piston chamber 202 and a right piston chamber 203. The hydraulic cylinder 2 is filled with hydraulic oil. A pressure relief gap 701 is formed between the outer wall of the piston 7 and the inner wall of the hydraulic cylinder 2, which connects the left piston chamber 202 and the right piston chamber 203. A baffle ring 8 is slidably mounted on the piston 7. The size of the outer wall of the baffle ring 8 is adapted to the size of the inner wall of the hydraulic cylinder 2. The baffle ring 8 is used to open and close the pressure relief gap 701, thereby connecting or disconnecting the left piston chamber 202 and the right piston chamber 203. The piston 7 is provided with a return flow hole 702. The right chamber 203 of the piston is connected to the left chamber 202 of the piston through the return flow hole 702. In order to ensure the damping effect, the diameter of the return flow hole 702 is small, which allows the hydraulic oil in the right chamber 203 of the piston to slowly flow back to the left chamber 202 of the piston through the return flow hole 702 when the door is closed, resulting in a better damping effect.

[0042] In some embodiments, such as Figures 7 to 9 As shown, the damping assembly also includes a guide seat 9 placed inside the left chamber 202 of the piston. The guide seat 9 is fixed to the piston rod 6 and abuts against the piston 7. A first through hole 901 is symmetrically arranged inside the guide seat 9, and a second through hole 902 is symmetrically arranged at the end of the guide seat 9 facing the piston 7. The first through hole 901 extends axially along the guide seat 9, and the second through hole 902 extends radially along the guide seat 9. The first through hole 901 connects with the second through hole 902. The left chamber 202 of the piston communicates with the pressure relief gap 701 through the first through hole 901 and the second through hole 902 in sequence. A guide ring 10 is sleeved on the guide seat 9, and a notch 1001 is opened on the guide ring 10. In this structure, due to the reduction in overall size, the stroke of the piston 7 is increased in order to ensure hydraulic effect and spring force. In order to prevent swaying and the generation of gaps, the guide seat 9 is added for guidance, which can ensure the stability of the piston 7's movement and the stability of the hydraulic damping effect.

[0043] In some embodiments, such as Figures 7 to 9As shown, the piston 7 has multiple pressure relief grooves 703 arranged at equal intervals in an annular shape. The pressure relief gap 701 connects to the right chamber 203 of the piston through the pressure relief grooves 703. One end of the piston 7 is provided with an annular flange 704, which forms the pressure relief gap 701 with the hydraulic cylinder body 2. When the baffle ring 8 abuts against the annular flange 704, the baffle ring 8 closes the pressure relief gap 701. The other end of the piston 7 is fitted with a limit ring 11. The baffle ring 8 can slide between the annular flange 704 and the limit ring 11. The limit ring 11 is used to limit the baffle ring 8 and prevent it from disengaging from the piston 7.

[0044] In this structure, when the door is opened, the door leaf drives the outer casing 1 to rotate relative to the camshaft 4. The camshaft 4 pushes the hydraulic cylinder 2 towards the spring 3, compressing the spring. During the movement of the hydraulic cylinder 2, the baffle ring 8 slides and abuts against the limit ring 11, opening the pressure relief gap 701. Most of the hydraulic oil in the left chamber 202 of the piston enters the right chamber 203 of the piston sequentially through the first through hole 901, the second through hole 902, the pressure relief gap 701, and the pressure relief groove 703. When the door is closed, under the force of the spring 3, the hydraulic cylinder 2 moves towards the camshaft 4. During the return process of the hydraulic cylinder 2, the baffle ring 8 slides and abuts against the annular flange 704, closing the pressure relief gap 701. The hydraulic oil in the right chamber 203 of the piston flows back to the left chamber 202 of the piston through the return flow hole 702. Because the size of the return flow hole 702 is small, the return speed is slow, allowing the door to close slowly and smoothly with good damping effect.

[0045] In some embodiments, such as Figure 1 As shown, the length, width and height ratio of the outer shell 1 is 196:28:25. In this embodiment, the length of the outer shell 1 is 196mm, the width is 28mm and the height is 25mm.

[0046] In some embodiments, such as Figure 1 and Figure 2 As shown, L-shaped seats 12 for covering cylindrical grooves 101 are symmetrically installed at both ends of the outer casing 1. A camshaft hole 102 is provided inside the outer casing 1, which is perpendicular to the cylindrical groove 101. The camshaft 4 is placed in the camshaft hole 102. Guide sleeves 19 are installed on both sides of the camshaft hole 102, and the guide sleeves 19 are fitted onto the camshaft 4. The camshaft 4 is fixed to the base 13. During installation, the outer casing 1 is fixed to the door leaf, and the base 13 is fixed to the ground.

[0047] In some embodiments, such as Figure 2 and Figure 3As shown, the hydraulic cylinder body 2 is fixed with a first end cover 14 at one end away from the camshaft 4, and a first spring seat 15 is fixed inside the outer shell 1. One end of the spring 3 is fitted onto the first end cover 14, and the other end is placed inside the first spring seat 15. The auxiliary hydraulic cylinder body 5 is fixed with a second end cover 16 at one end away from the camshaft 4, and a second spring seat 17 is fixed inside the outer shell 1. An auxiliary spring 18 is installed between the second end cover 16 and the second spring seat 17.

[0048] In some embodiments, such as Figure 10 and Figure 11 As shown, a damping assembly for generating a damping effect is installed inside the auxiliary hydraulic cylinder 5. Since the auxiliary hydraulic cylinder 5 is designed to handle emergencies, its stroke is relatively short. Therefore, the difference between the damping assembly in the auxiliary hydraulic cylinder 5 and the damping assembly in the hydraulic cylinder 2 is that the guide seat 9 component has been removed. Specifically, the damping assembly in the auxiliary hydraulic cylinder 5 includes an auxiliary piston rod 20, an auxiliary piston 21, an auxiliary flow-blocking ring 22, and an auxiliary limiting ring 23.

[0049] Within the auxiliary hydraulic cylinder 5, the right chamber 503 of the auxiliary piston is connected to the left chamber 502 of the auxiliary piston via the auxiliary pressure relief groove 213 and the auxiliary pressure relief gap 211. Hydraulic oil in the left chamber 502 flows back to the right chamber 503 of the auxiliary piston through the auxiliary return flow hole 212. The auxiliary flow-blocking ring 22 is used to open and close the auxiliary pressure relief gap 211. Its hydraulic damping principle is similar to that of the hydraulic cylinder 2, and will not be described further in this embodiment.

[0050] The same or similar parts between the various embodiments in this specification can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments.

[0051] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A hydraulic spring hinge for narrow doors, characterized by: The device includes an elongated outer shell (1), a hydraulic cylinder (2) slidably mounted inside the outer shell (1), and a spring (3) abutting between the hydraulic cylinder (2) and the outer shell (1). A cylindrical groove (101) is provided extending along the length of the outer shell (1), and the hydraulic cylinder (2) and the spring (3) are coaxially arranged in the cylindrical groove (101). A camshaft (4) is inserted into one side of the outer shell (1) located on the hydraulic cylinder (2), and the hydraulic cylinder (2) abuts against the outer wall of the camshaft (4).

2. The hydraulic spring hinge for narrow door as claimed in claim 1, wherein: An auxiliary hydraulic cylinder (5) is slidably installed inside the outer shell (1). The auxiliary hydraulic cylinder (5) is coaxially arranged in the cylindrical groove (101). The auxiliary hydraulic cylinder (5) and the hydraulic cylinder (2) are respectively arranged on both sides of the camshaft (4). The auxiliary hydraulic cylinder (5) is used to provide hydraulic buffer when subjected to external force in the same direction during the closing process.

3. The hydraulic spring hinge for narrow door as claimed in claim 1, wherein: The upper end of the camshaft (4) is provided with a limiting thin wall (401), and a widening groove (402) is formed on the lower side of the limiting thin wall (401). The hydraulic cylinder (2) is provided with a top block (201) that is adapted to the widening groove (402) at one end facing the camshaft (4).

4. The hydraulic spring hinge for narrow door as claimed in claim 2, wherein: The outer circumferential wall of the camshaft (4) is symmetrically and spaced apart with first cam walls (403), and a second cam wall (404) is formed concave between the two first cam walls (403). The auxiliary hydraulic cylinder (5) is provided with a triangular top (501) that abuts against the second cam wall (404). The first cam walls (403) are used to push the hydraulic cylinder (2) to slide, and the second cam wall (404) is used to push the auxiliary hydraulic cylinder (5) to slide.

5. The hydraulic spring hinge for narrow doors as claimed in claim 1, wherein: The hydraulic cylinder (2) is equipped with a damping assembly for generating a damping effect. The damping assembly includes a piston rod (6), a piston (7), and a baffle ring (8). One end of the piston rod (6) is fixedly connected to the outer shell (1), and the other end is inserted into the hydraulic cylinder (2) and fixed with the piston (7). The piston (7) divides the inner cavity of the hydraulic cylinder (2) into a left piston chamber (202) and a right piston chamber (203). The outer wall of the piston (7) is connected to the hydraulic cylinder. A pressure relief gap (701) is formed between the inner walls of the cylinder (2), and the pressure relief gap (701) is used to connect the left chamber (202) of the piston and the right chamber (203) of the piston; the flow-blocking ring (8) is slidably installed on the piston (7), and the flow-blocking ring (8) is used to open and close the pressure relief gap (701); a return flow hole (702) is provided in the piston (7), and the right chamber (203) of the piston is connected to the left chamber (202) of the piston through the return flow hole (702).

6. The hydraulic spring hinge for narrow doors as claimed in claim 5, wherein: The damping assembly also includes a guide seat (9) placed in the left chamber (202) of the piston. The guide seat (9) is fixed on the piston rod (6) and abuts against the piston (7). A first through hole (901) is symmetrically arranged in the guide seat (9). A second through hole (902) is symmetrically arranged at one end of the guide seat (9) facing the piston (7). The left chamber (202) of the piston communicates with the pressure relief gap (701) in sequence through the first through hole (901) and the second through hole (902). A guide ring (10) is sleeved on the guide seat (9). A notch (1001) is opened on the guide ring (10).

7. The hydraulic spring hinge for narrow door as claimed in claim 5 wherein: The piston (7) is provided with a plurality of pressure relief grooves (703) at equal intervals in an annular shape, and the pressure relief gap (701) is connected to the right chamber (203) of the piston through the pressure relief grooves (703); one end of the piston (7) is provided with an annular flange (704), and the annular flange (704) and the hydraulic cylinder (2) form the pressure relief gap (701); the other end of the piston (7) is fitted with a limiting ring (11), and the flow-blocking ring (8) can slide between the annular flange (704) and the limiting ring (11).

8. The hydraulic spring hinge for narrow doors as claimed in claim 1, wherein: The outer shell (1) is symmetrically equipped with L-shaped seats (12) for covering the cylindrical groove (101) at both ends. The outer shell (1) is provided with a camshaft hole (102) arranged perpendicularly to the cylindrical groove (101). The camshaft (4) is placed in the camshaft hole (102). Guide sleeves (19) are respectively installed on both sides of the camshaft hole (102). The camshaft (4) is fixed on the base (13).

9. The hydraulic spring hinge for narrow door as claimed in claim 2 wherein: The hydraulic cylinder body (2) is fixed with a first end cap (14) at one end away from the camshaft (4), and a first spring seat (15) is fixed inside the outer shell (1). One end of the spring (3) is fitted onto the first end cap (14), and the other end is placed inside the first spring seat (15). The auxiliary hydraulic cylinder body (5) is fixed with a second end cap (16) at one end away from the camshaft (4), and a second spring seat (17) is fixed inside the outer shell (1). An auxiliary spring (18) is installed between the second end cap (16) and the second spring seat (17).

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