360-degree rotatable cam hydraulic door closer for narrow frame doors

Abstract

To provide a 360-degree rotatable cam hydraulic door closer for narrow frame doors.SOLUTION: A camshaft is supported in a door closer housing 100 so as to rotatable 360 degrees, and through interaction between a damping roller 310 that is rotatably installed on a bidirectional piston 300 and a left closing arc groove and a right closing arc groove that are installed on the outer circumferential surface of the eccentric cam 210, it is realized that the door is kept closed when it is rotated 0, 180, or 360 degrees. At this time, the damping roller 310 is fitted into the left closing arc groove or the right closing arc groove and is fixed relatively to the eccentric cam 210, thereby achieving the effect of positioning the door opening and closing angle and finally stopping the door. At the same time, during the process of the camshaft rotating in the door closer housing 100, the damping roller 310 is subjected to the damping action of the eccentric cam 210, so that the instantaneous speed when the door is opened or closed is reduced and sufficient buffering is provided.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to the technical field of door closers, and particularly to a cam hydraulic door closer that can rotate 360 degrees for narrow-edge doors.

Background Art

[0002] A door closer is a hydraulic device such as a spring provided at the upper part of a door. After the door is opened, it is compressed and released to automatically close the door, having the function of a spring door. After the door is opened, it is ensured that the door can be accurately and timely closed to the initial position.

[0003] During the process of the spring being released, the hydraulic oil in the left chamber of the door closer is compressed and the check valve is closed. The hydraulic oil flows out through the gap between the door closer housing and the plunger, and returns to the right chamber through two flow paths provided with small holes in the plunger and the throttle valve core. Therefore, the hydraulic oil becomes the resistance for the spring to open, and the cushion effect by throttling is obtained, and the closing speed of the door is controlled.

[0004] Most common door closers only allow the door to be opened up to 90 degrees. A few allow the door to be opened up to 180 degrees. Therefore, the above-mentioned door closers cannot be used when the door needs to be opened and closed more than 180 degrees, the applicable range is narrow, and they cannot be applied to doors that can be entered and exited from both sides, and their use is restricted.

Summary of the Invention

Problems to be Solved by the Invention

[0005] The object of the present invention is to provide a cam hydraulic door closer that can rotate 360 degrees for narrow-edge doors, and to solve the technical problems of conventional door closers with a narrow applicable range and that cannot be applied to doors that can be entered and exited from both sides.

Means for Solving the Problems

[0006] To achieve the above objectives, a 360-degree rotatable cam hydraulic door closer for narrow-frame doors according to an embodiment of the present invention comprises a door closer housing, a camshaft, a bidirectional piston, and a drive spring. An internal cavity is formed inside the door closer housing along its axial direction. The camshaft has an axial direction perpendicular to the extension direction of the door closer housing, is supported within the door closer housing so as to be 360 ​​degrees rotatable, and has an eccentric cam at its center that is synchronously rotatable. The bidirectional piston is slidably mounted within the lumen, located to the right of the eccentric cam, with a damping roller rotatably mounted on the side closer to the eccentric cam. The drive spring is housed within the internal cavity and contacts the bidirectional piston and the door closer housing, respectively, biasing the damping roller to always flexibly contact the outer circumferential surface of the eccentric cam. On the outer circumferential surface of the eccentric cam, a left-side closed arc groove, an upper damping protrusion, a right-side closed arc groove, and a lower damping protrusion are sequentially arranged in a clockwise direction. The left-side closed arc groove and the right-side closed arc groove are located on the same horizontal line, and the upper damping protrusion and the lower damping protrusion are located on the same vertical line.

[0007] Preferably, the bidirectional piston is provided with a fixing pin on the side closer to the eccentric cam. The damping roller is rotatably attached to the fixing pin.

[0008] Preferably, the drive spring comprises an inner spring and an outer spring, the outer spring being fitted over the outside of the inner spring, one end of the outer spring and the inner spring simultaneously contacting the door closer housing, and the other end of the outer spring and the inner spring simultaneously contacting the bidirectional piston.

[0009] Preferably, the door closer housing has a first bearing cylinder installed at a position corresponding to the lower end of the camshaft, a position limiting mounting seat installed at a position corresponding to the upper end of the camshaft, a second bearing cylinder installed on the limiting mounting seat, the midpoints of the first bearing cylinder and the second bearing cylinder are located on the same axis, and the camshaft is provided passing through the first bearing cylinder and the second bearing cylinder.

[0010] Preferably, an outer circumferential sealing ring is installed between the outer end face of the position limiting mounting seat and the door closer housing, and an inner circumferential sealing ring is installed between the inner end face of the position limiting mounting seat and the camshaft.

[0011] Preferably, the door closer housing comprises a housing body and a sealing end cover. The housing body is hollow inside, has openings on both sides, and the camshaft is rotatably connected to the housing body. The sealing end caps consist of two parts, each installed in an opening on either side of the housing body, and by enclosing each other, they form the inner cavity. An end cap seal ring is installed between the outer end surface of the sealing end cap and the housing body.

[0012] Preferably, the system further comprises an automatic compensating valve assembly that is slidably installed within the lumen and located to the left of the eccentric cam. The internal lumen is partitioned by the automatic compensating valve assembly and the bidirectional piston, forming a first oil passage located to the left of the automatic compensating valve assembly, a second oil passage located to the right of the bidirectional piston, and a third oil passage located between the automatic compensating valve assembly and the bidirectional piston. The first, second, and third oil passages are all filled with hydraulic fluid, and the hydraulic fluid in the second and third oil passages is in communication with the bidirectional piston. The automatic compensating valve assembly is configured such that when the pressure in the first oil passage exceeds a predetermined threshold, the automatic compensating valve assembly allows the flow of hydraulic fluid between the first oil passage and the third oil passage.

[0013] Preferably, the automatic compensating valve assembly comprises a valve piston, a valve body, a valve core member, and a core spring. The valve piston is slidably mounted within the lumen. The valve body is mounted inside the valve piston, and valve passages are provided through it that communicate with the first oil passage and the third oil passage, respectively. The valve core member is movably provided within the valve passage and is used to open or close the valve passage. The core spring is housed within the valve passage, with one end connected to the valve body and the other end connected to the valve core member, and biases the valve core member to block the valve passage.

[0014] The above-described means of the 360-degree rotatable cam-hydraulic door closer for narrow-frame doors according to the present invention have at least one of the following technical effects. The structure of this 360-degree rotatable cam-hydraulic door closer for narrow-frame doors is novel. The camshaft is supported within the door closer housing so as to be 360 ​​degrees rotatable, and the interaction between the damping roller, which is rotatably mounted on a bidirectional piston, and the left-side closing arc groove and the right-side closing arc groove, which are mounted on the outer surface of the eccentric cam, enables the door to remain closed when rotated to 0 degrees, 180 degrees, and 360 degrees. At this time, the damping roller is fitted into the left-side closing arc groove or the right-side closing arc groove and fixed relative to the eccentric cam. This prevents the eccentric cam from continuing to rotate within the door closer housing, achieving a positioning effect with respect to the opening and closing angle of the door, and ultimately stopping the door. At the same time, as the camshaft rotates within the door closer housing, the damping rollers act as a damper on the eccentric cam, reducing the instantaneous speed during door opening and closing and providing sufficient cushioning. Thus, the present invention achieves an opening range from 0 to 360 degrees, meeting the needs of revolving door users and providing convenient door opening on both sides.

[0015] To more clearly illustrate the technical aspects of the embodiments of the present invention, the drawings required in the description of the embodiments or prior art are briefly described below. It is clear that the drawings in the following description represent only a few embodiments of the present invention, and those skilled in the art can obtain other drawings from these drawings without any creative effort. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram (1) showing the internal structure of a 360-degree rotatable cam hydraulic door closer for narrow-frame doors according to an embodiment of the present invention. [Figure 2] This is a schematic diagram 2 showing the internal structure of a 360-degree rotatable cam hydraulic door closer for narrow-frame doors according to an embodiment of the present invention. [Figure 3]It is a schematic diagram showing the structure of an eccentric cam according to an embodiment of the present invention. [Figure 4] It is a schematic diagram showing the structure of a door closer housing according to an embodiment of the present invention. [Figure 5] It is a schematic diagram showing the structure of an automatic compensation valve assembly according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, embodiments of the present invention will be described in detail. Examples of the embodiments are shown in the drawings. Here, the same or similar reference numerals represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the drawings are exemplary for explaining the embodiments of the invention and should not be construed as limitations on the present invention.

[0018] In the description of the embodiments of the present invention, the orientation or positional relationship indicated by terms such as "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. is the orientation or positional relationship shown based on the drawings, and is for the purpose of explaining and simplifying the description of the embodiments of the present invention, and does not indicate or imply that the device or member needs to have a specific orientation, be constructed in a specific orientation, and operate, so it should not be construed as a limitation on the present invention.

[0019] Furthermore, the terms "first" and "second" are used for the purpose of explanation and should not be construed as indicating or implying relative importance or the number of technical features. Therefore, the features defined as "first" and "second" explicitly or implicitly include one or more features. In the description of the embodiments of the present invention, "plurality" means two or more unless specifically and clearly limited.

[0020] In embodiments of the present invention, terms such as “attachment,” “connection,” “connection,” and “fixed” should be understood broadly unless otherwise specifically defined. For example, a fixed connection may be a removable connection or an integral connection, a mechanical connection or an electrical connection, a direct connection or an indirect connection through an intermediate medium, an internal communication between two members or an interaction between two members. Those skilled in the art will be able to understand the specific meaning of the above terms in embodiments of the present invention based on the specific circumstances.

[0021] (First Embodiment) In the first embodiment of the present invention, as shown in Figures 1 to 3, a 360-degree rotatable cam hydraulic door closer for narrow-frame doors comprises a door closer housing 100, a camshaft 200, a bidirectional piston 300, and a drive spring 400.

[0022] An internal cavity 110 is formed inside the door closer housing 100, along its axial direction.

[0023] The camshaft 200 is axially perpendicular to the extension direction of the door closer housing 100, supported within the door closer housing 100 so as to be 360 ​​degrees rotatable, and has a synchronously rotatable eccentric cam 210 installed in the center.

[0024] The bidirectional piston 300 is slidably mounted within the lumen 110 and is located to the right of the eccentric cam 210, with a damping roller 310 rotatably mounted on the side closer to the eccentric cam 210.

[0025] The drive spring 400 is housed within the internal cavity 110 and contacts the bidirectional piston 300 and the door closer housing 100, respectively, biasing the damping roller to always flexibly contact the outer surface of the eccentric cam.

[0026] On the outer circumferential surface of the eccentric cam 210, a left-side closed arc-shaped groove 220, an upper damping projection 230, a right-side closed arc-shaped groove 240, and a lower damping projection 250 are sequentially arranged in a clockwise direction. The left-side closed arc-shaped groove 220 and the right-side closed arc-shaped groove 240 are located on the same horizontal line. The upper damping projection 230 and the lower damping projection 250 are located on the same vertical line.

[0027] Specifically, in this embodiment, the 360-degree rotatable cam-hydraulic door closer for narrow-frame doors has a novel structure. The camshaft 200 is supported within the door closer housing 100 so as to be 360 ​​degrees rotatable, and the interaction between the damping roller 310, which is rotatably mounted on the bidirectional piston 300, and the left closing arc groove 220 and the right closing arc groove 240, which are mounted on the outer surface of the eccentric cam 210, enables the door to remain closed when rotated to 0, 180, and 360 degrees. At this time, the damping roller 310 is fitted into the left closing arc groove 220 or the right closing arc groove 240 and fixed relative to the eccentric cam 210. This prevents the eccentric cam 210 from continuing to rotate within the door closer housing 100, achieving a positioning effect with respect to the opening and closing angle of the door and ultimately stopping the door. Simultaneously, as the camshaft 200 rotates within the door closer housing 100, the damping roller 310 dampens the eccentric cam 210, reducing the instantaneous speed during door opening and closing, and providing sufficient cushioning. Thus, the present invention enables opening from 0 to 360 degrees, meeting the usage needs of revolving doors and providing convenient door opening on both sides.

[0028] (Second embodiment) In a second embodiment of the present invention, as shown in Figures 1-3, the bidirectional piston 300 is provided with a fixing pin 320 on the side closer to the eccentric cam 210. The damping roller 310 is rotatably attached to the fixing pin 320.

[0029] Specifically, in this embodiment, the damping roller 310 is rotatably mounted on the bidirectional piston 300 via a fixing pin 320, making it easy to install and remove the damping roller 310, and easy to maintain or replace the damping roller 310.

[0030] Other parts of this embodiment are the same as those of the first embodiment, and for features not described in this embodiment, the interpretation of the first embodiment applies, and their description is omitted here.

[0031] (Third embodiment) In a third embodiment of the present invention, as shown in Figures 1 and 2, the drive spring 400 comprises an inner spring 410 and an outer spring 420. The outer spring 420 is placed over the outside of the inner spring 410. One end of the outer spring 420 and the inner spring 410 simultaneously contacts the door closer housing 100. The other ends of the outer spring 420 and the inner spring 410 simultaneously contact the bidirectional piston 300.

[0032] Specifically, in this embodiment, the drive spring 400 has a simple structure and a rational design. When the drive spring 400 is subjected to force and expands or contracts, the inner spring 410 and the outer spring 420 both expand or contract accordingly without interfering with each other. Therefore, when the inner spring 410 and the outer spring 420 are used in combination, deformation is less likely to occur, and the service life of the inner spring 410 and the outer spring 420 can be effectively extended. The combined design significantly improves the elasticity of the drive spring 400 and ensures the verticality and stability of the spring force. Furthermore, it can effectively prevent the inner spring 410 and the outer spring 420 from being damaged by excessive load.

[0033] Other parts of this embodiment are the same as those of the first embodiment, and for features not described in this embodiment, the interpretation of the first embodiment applies, and their description is omitted here.

[0034] (Fourth embodiment) In a fourth embodiment of the present invention, as shown in Figure 1, the door closer housing 100 has a first bearing cylinder 120 installed at a position corresponding to the lower end of the camshaft 200, and a position limiting mounting seat 130 installed at a position corresponding to the upper end of the camshaft 200. A second bearing cylinder 140 is installed on the position limiting mounting seat 130. The midpoints of the first bearing cylinder 120 and the second bearing cylinder 140 lie on the same axis. The camshaft 200 is provided passing through the first bearing cylinder 120 and the second bearing cylinder 140.

[0035] Specifically, in this embodiment, the first bearing cylinder 120 and the second bearing cylinder 140 primarily serve to fix the camshaft 200 in place. The first bearing cylinder 120 and the second bearing cylinder 140 reduce vibrations when the camshaft 200 moves, maintaining the balance and stability of the camshaft 200, reducing friction and wear, and extending the life of the camshaft 200.

[0036] Other parts of this embodiment are the same as those of the first embodiment, and for features not described in this embodiment, the interpretation of the first embodiment applies, and their description is omitted here.

[0037] (Fifth embodiment) In the fifth embodiment of the present invention, as shown in Figure 1, an outer peripheral seal ring 500 is installed between the outer end face of the position limiting mounting seat 130 and the door closer housing 100. An inner peripheral seal ring 600 is installed between the inner end face of the position limiting mounting seat 130 and the camshaft 200.

[0038] Specifically, in this embodiment, on the one hand, the outer peripheral seal ring 500 always tightly abuts against the outer end face of the position limiting mounting seat 130 and the door closer housing 100, respectively, thereby sealing the space between the position limiting mounting seat 130 and the door closer housing 100. On the other hand, the inner peripheral seal ring 600 always tightly abuts against the inner end face of the position limiting mounting seat 130 and the camshaft 200, respectively, thereby sealing the space between the position limiting mounting seat 130 and the camshaft 200.

[0039] Other parts of this embodiment are the same as those of the fourth embodiment, and for features not described in this embodiment, the interpretation of the fourth embodiment applies, and their description is omitted here.

[0040] (Sixth Embodiment) In the sixth embodiment of the present invention, as shown in Figure 4, the door closer housing 100 comprises a housing body 150 and a sealing end cover 160.

[0041] The housing body 150 is hollow inside and has openings on both sides, and the camshaft 200 is rotatably connected to the housing body 150.

[0042] There are two sealing end covers 160, each installed in the openings on both sides of the housing body 150, and they surround each other to form an inner cavity 110. An end cover seal ring 170 is installed between the outer end face of the sealing end cover 160 and the housing body 150.

[0043] Specifically, in this embodiment, the housing body 150 and the two sealing end covers 160 in the door closer housing 100 are detachably connected. On the one hand, the operation of maintaining the entire 360-degree rotatable cam hydraulic door closer for narrow-frame doors becomes extremely easy, and workers can quickly and conveniently disassemble and maintain it. On the other hand, the removable structure makes it easy to maintain or replace the individual housing body 150 or sealing end covers 160, thereby reducing maintenance costs.

[0044] Other parts of this embodiment are the same as those of the first embodiment, and for features not described in this embodiment, the interpretation of the first embodiment applies, and their description is omitted here.

[0045] (Seventh Embodiment) In the seventh embodiment of the present invention, as shown in Figures 1-2, a 360-degree rotatable cam hydraulic door closer for narrow-frame doors further comprises an automatic compensating valve assembly 700 slidably installed within a lumen 110 and located to the left of an eccentric cam 210. The lumen 110 is partitioned by the automatic compensating valve assembly 700 and a bidirectional piston 300, forming a first oil passage 810 located to the left of the automatic compensating valve assembly 700, a second oil passage 820 located to the right of the bidirectional piston 300, and a third oil passage 830 located between the automatic compensating valve assembly 700 and the bidirectional piston 300. The first oil passage 810, the second oil passage 820, and the third oil passage 830 are all filled with hydraulic fluid. The hydraulic fluid in the second oil passage 820 and the third oil passage 830 are in communication via the bidirectional piston 300. The automatic compensating valve assembly 700 is configured to allow the flow of hydraulic fluid between the first oil passage 810 and the third oil passage 830 when the pressure in the first oil passage 810 exceeds a predetermined threshold.

[0046] Specifically, in this embodiment, hydraulic fluid is present in all three oil passages: the first oil passage 810, the second oil passage 820, and the third oil passage 830. As the door closer housing 100 rotates in conjunction with the rotation of the door body, the position of the bidirectional piston 300 on the camshaft 200 changes. This changes the volume of the second oil passage 820, causing hydraulic fluid to flow between the second oil passage 820 and the third oil passage 830, creating a pressure difference between the first oil passage 810 and the third oil passage 830, and changing the state of the automatic compensation valve assembly 700. As a result, hydraulic fluid flows between the first oil passage 810 and the third oil passage 830, maintaining a balance in the pressure difference between the first oil passage 810 and the third oil passage 830. In other words, the flow of hydraulic fluid in the first oil passage 810, the second oil passage 820, and the third oil passage 830 can be matched to the movement of the door body.

[0047] Other parts of this embodiment are the same as those of the first embodiment, and for features not described in this embodiment, the interpretation of the first embodiment applies, and their description is omitted here.

[0048] (Eighth embodiment) In the eighth embodiment of the present invention, as shown in Figure 5, the automatic compensating valve assembly 700 comprises a valve piston 710, a valve body 720, a valve core member 730, and a core spring 740.

[0049] The valve piston 710 is slidably mounted within the lumen 110.

[0050] The valve body 720 is installed inside the valve piston 710, and valve passages 721 are provided through it, communicating with the first oil passage 810 and the third oil passage 830, respectively.

[0051] The valve core member 730 is movably provided within the valve passage 721 and is used to open or close the valve passage 721.

[0052] The core spring 740 is housed in the valve passage 721, with one end connected to the valve body 720 and the other end connected to the valve core member 730, which biases the valve core member 730 to block the valve passage 721.

[0053] Specifically, in this embodiment, the movement of the valve core member 730 achieves the opening or closing of the valve passage 721. The placement of the core spring 740 ensures the accuracy of the movement of the valve core member 730. When a pressure difference occurs between the first oil passage 810 and the third oil passage 830, the hydraulically pushed valve core member 730 moves within the valve passage 721, overcoming the elastic force of the core spring 740, thereby opening the valve passage 721. When the pressure difference between the first oil passage 810 and the third oil passage 830 is balanced, the valve core member 730 is pushed by the elastic force of the core spring 740, moves within the valve passage 721, returns to its original position, and closes the valve passage 721. The state of the automatically compensating valve assembly 700 changes automatically and is highly reliable.

[0054] Other parts of this embodiment are the same as those of the seventh embodiment, and for features not described in this embodiment, the interpretation of the seventh embodiment applies, and their description is omitted here.

[0055] The foregoing describes only preferred embodiments of the present invention and does not limit the invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the invention are all included within the scope of protection of the present invention. [Explanation of Symbols]

[0056] 100 Door Closer Housing 110 Luminal body 120 First bearing cylinder 130 Position restriction mounting base 140 Second bearing cylinder 150 Housing Body 160 sealed end lid 170 End cap sealing ring 200 camshaft 210 Eccentric Cam 220 Left side closed arc groove (First arc-shaped recess) 230 Upper damping protrusion (First damping protrusion) 240 Right side closed arc groove (Second arc-shaped recess) 250 Lower damping protrusion (Second damping protrusion) 300 bidirectional pistons 310 Damping Roller 320 Fixing pins 400 drive spring 410 Inner spring 420 Outer spring 500 Outer circumference sealing ring 600 Inner Circumference Seal Ring 700 Automatic Compensation Valve Assembly 710 Valve Piston 720 Valve body 721 Valve passage 733 Valve core component 740 Core Spring 810 First oil channel 820 Second oil channel 830 Third oil channel

Claims

1. A 360-degree rotatable cam hydraulic door closer for narrow-frame doors, The door closer housing comprises a camshaft, a bidirectional piston, a drive spring, an automatic compensation valve assembly, a cylindrical member, and a spring member. Inside the door closer housing, an internal cavity is formed along its axial direction. The camshaft has an axial direction perpendicular to the extension direction of the door closer housing, is supported within the door closer housing so as to be 360 ​​degrees rotatable, and has an eccentric cam installed in the center that is synchronously rotatable. The bidirectional piston is slidably mounted within the internal cavity, and a damping roller is rotatably mounted on the side of the eccentric cam closest to the eccentric cam, The drive spring is housed within the internal cavity and contacts the bidirectional piston and the door closer housing, respectively, and biases the damping roller to always flexibly contact the outer circumferential surface of the eccentric cam. The outer circumferential surface of the eccentric cam is provided with a first arc-shaped recess, a first damping protrusion, a second arc-shaped recess, and a second damping protrusion, wherein the first arc-shaped recess and the second arc-shaped recess are located on the same horizontal line, and the first damping protrusion and the second damping protrusion are located on the same vertical line. The automatic compensation valve assembly is slidably installed within the lumen and is located on the opposite side of the drive spring of the eccentric cam, The internal body is partitioned by the automatic compensating valve assembly and the bidirectional piston, and a first oil passage is formed on the side of the automatic compensating valve assembly opposite the eccentric cam, a second oil passage is formed on the drive spring side of the bidirectional piston, and a third oil passage is formed between the automatic compensating valve assembly and the bidirectional piston, and the first, second, and third oil passages are all filled with hydraulic fluid, and the hydraulic fluid in the second and third oil passages is in communication with the bidirectional piston. The automatic compensation valve assembly is configured such that when the pressure in the first oil passage exceeds a predetermined threshold, the automatic compensation valve assembly allows the flow of hydraulic fluid between the first oil passage and the third oil passage. The aforementioned automatic compensating valve assembly comprises a valve piston, a valve body, a valve core member, and a core spring. The valve piston is slidably mounted within the lumen, The valve body is mounted inside the valve piston, and valve passages are provided through it that communicate with the first oil passage and the third oil passage, respectively. The valve core member is movably provided within the valve passage and is used to open or close the valve passage. The core spring is housed within the valve passage, with one end connected to the valve body and the other end connected to the valve core member, and biases the valve core member to block the valve passage. The cylindrical member is installed inside the valve piston, the valve body is installed inside the cylindrical member, one end of the cylindrical member abuts against the camshaft, the other end of the cylindrical member abuts against the spring member, one end of the spring member abuts against the cylindrical member, and the other end of the spring member abuts against the door closer housing. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

2. A 360-degree rotatable cam hydraulic door closer for a narrow-frame door according to claim 1, The aforementioned bidirectional piston is provided with a fixing pin on the side closer to the eccentric cam. The damping roller is rotatably attached to the fixing pin. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

3. A 360-degree rotatable cam hydraulic door closer for a narrow-frame door according to claim 1, The drive spring comprises an inner spring and an outer spring, the outer spring being fitted over the outside of the inner spring, one end of the outer spring and the inner spring simultaneously contacting the door closer housing, and the other end of the outer spring and the inner spring simultaneously contacting the bidirectional piston. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

4. A 360-degree rotatable cam hydraulic door closer for a narrow-frame door according to claim 1, The door closer housing has a first bearing cylinder installed at a position corresponding to one end of the camshaft, a position limiting mounting seat installed at a position corresponding to the other end of the camshaft, a second bearing cylinder installed on the limiting mounting seat, the midpoints of the first bearing cylinder and the second bearing cylinder are located on the same axis, and the camshaft is provided passing through the first bearing cylinder and the second bearing cylinder. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

5. A 360-degree rotatable cam hydraulic door closer for a narrow-frame door according to claim 4, An outer circumferential sealing ring is installed between the outer end face of the position limiting mounting seat and the door closer housing, and an inner circumferential sealing ring is installed between the inner end face of the position limiting mounting seat and the camshaft. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

6. A 360-degree rotatable cam hydraulic door closer for a narrow-frame door according to claim 1, The door closer housing comprises a housing body and a sealed end cover. The housing body is hollow inside, has openings on both sides, and the camshaft is rotatably connected to the housing body. The aforementioned sealing end caps consist of two parts, each installed in the openings on both sides of the housing body, and by enclosing each other, they form the inner cavity, with an end cap seal ring installed between the outer end surface of the sealing end cap and the housing body. A 360-degree rotatable cam-type hydraulic door closer for narrow-frame doors, characterized by the following features.

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