TWM484623U - Oil-free automatic door closer - Google Patents

Description

Oil-free automatic door closer

The utility model relates to a door closing device, in particular to a non-hydraulic oil-free automatic door closing device.

The hydraulic type door closer is a common automatic door closing device. For example, the Republic of China Announcement No. M466959 patent discloses a hydraulic pressure door closer structure. The hydraulic pressure door closer structure includes a base, a piston and a shaft unit. , an elastic member and a regulating valve. The base has a chamber inside; the piston is assembled in a middle portion of the chamber to divide the chamber into a first chamber and a second chamber that can be filled with oil. In addition, a side of the base is further provided with a return passage connecting the first chamber and the second chamber. On the other hand, the piston is internally provided with a through hole for the reverse function, and the through hole can communicate with the first chamber and the second chamber of the base. The rotating shaft unit is disposed in the first chamber and protrudes from a top surface of the base to connect a door leaf, and can be rotated by the pushing action of the opening door. The elastic member is used to strike the piston, and the regulating valve is assembled on the base to adjust the flow cross-sectional area of the return passage. Accordingly, the door closer can control the switch of the door leaf by the oil pressure adjustment mechanism. However, such a hydraulic type automatic door closer requires oil to be poured inside, and is a design that is less friendly to environmental protection. In addition, due to the internal need to inject oil, special attention should be paid to the oil leakage design in terms of mechanism design, so it is not conducive to production and construction in construction and assembly.

Therefore, the purpose of the present invention is to provide an automatic door closer that can automatically close the door leaf without using a hydraulic method.

The novel oil-free automatic door closing device is used for automatic closing operation of a door. The oil-free automatic door closing device comprises: a casing, a rotating mechanism, a guiding sliding seat and a closing door driving control mechanism. The housing is mounted to a fixture. The rotating mechanism includes a shaft and a cam. The shaft is installed in the casing and can be engaged with the door shaft of the door or connected with a connecting mechanism connecting the door, and the door is closed by the rotation thereof. The cam is coupled to the shaft and pivoted about the shaft, and has an outer edge having at least one shortest wheel diameter and at least one longest wheel diameter, and concavely forming a short wheel diameter corresponding to the shortest wheel diameter Depression. A guide slide is mounted in the housing and the position corresponds to the cam. The door drive control mechanism is mounted in the housing and includes a shaft assembly, a brake spring and a door closing speed spring. The rod body assembly has a top rod, a baffle and an end plate. The ram is movably disposed in the guiding slide along the axial direction thereof, and one end thereof abuts against the outer edge of the cam. The baffle is disposed at the other end of the ram, and is spaced apart from the guiding slider, and has a braking spring baffle surface of the guiding sliding seat and a closing speed of the guiding sliding sliding seat Spring baffle face. The end plate is disposed in the housing and is disposed at a position corresponding to the baffle and spaced apart from the baffle. The brake spring has a fixing end and a free end, and is sleeved on the ejector pin and interposed between the guiding sliding seat and the baffle, and the fixing end is coupled to the guiding sliding seat. The closing speed spring is disposed between the baffle and the end plate, and the two ends are respectively coupled to the closing speed spring baffle surface of the baffle and the end plate.

Wherein, when the door leaf is closed, the shortest wheel diameter of the outer edge of the cam is connected to the jack. When the door leaf is opened, the door closing speed spring constantly provides an elastic force to the end plate, so that the ejector pin Placing a force on the cam along its axial direction, causing the cam to rotate and tending to be in contact with the ram at its shortest wheel diameter, and driving the shaft and the linkage mechanism or the door leaf to cause the door to gradually close . When the door leaf is opened at a specific angle (for example, 30 degrees), when the short wheel diameter concave portion of the cam is in contact with the ejector pin, the free end of the brake spring will abut against the brake spring baffle surface of the baffle plate. And offsetting the partial elastic force provided by the closing speed spring, the closing speed of the door leaf is gradually slowed down.

In a preferred embodiment, the cam is a symmetrical cam and has an elliptical cross section, the outer edge of which has a shortest wheel diameter at the short axis of the corresponding ellipse, and the long axis of the corresponding ellipse. Each has a longest wheel diameter, and a long wheel diameter recess is respectively formed in the corresponding longest wheel diameter; when the door is opened to 90 degrees, the long wheel diameter concave portion of the cam is opposite to the top rod Connected so that the cam tends not to rotate.

In a preferred embodiment, the end plate is disposed in the housing in an adjustable position, and a specific separation distance between the end plate and the baffle causes the closing speed spring to provide a corresponding elasticity. force.

In a preferred embodiment, the rod assembly further has a supporting spring tube coupled to the baffle and located between the baffle and the end plate for the closing speed spring to be placed thereon . In addition, the rod assembly further has a screw locking member for screwing the end plate to the supporting spring tube and adjusting the distance between the end plate and the baffle.

In an embodiment, the guiding slide comprises a bottom wall and two vertical walls spaced apart from each other and arranged on the bottom wall, the vertical walls for the ejector to be inserted therethrough in the axial direction. In addition, the ram further has a stop pin protruding radially, the stop pin being located between the two vertical walls of the guide slide to limit the amount of displacement of the ram in its axial direction.

The effect of the novel is that the new oil-free automatic door closer passes through the cam The edge contour design, as well as the lever combination, the brake spring, and the closing speed spring, allow the oil-free automatic door closer to provide automatic closing of the door, buffer deceleration when closed, and positioning at a specific position.

1‧‧‧ Oil-free automatic door closer

11‧‧‧Linked institutions

12‧‧‧ door leaf

2‧‧‧Shell

21‧‧‧ bottom case

22‧‧‧ Cover

23‧‧‧ Pedestal

24‧‧‧Upper cover

3‧‧‧Rotating mechanism

31‧‧‧ shaft

32‧‧‧ Lower bearing

33‧‧‧ cam

331‧‧‧ Shortest wheel diameter

332‧‧‧Longest wheel

333‧‧‧Short wheel diameter depression

334‧‧‧Long wheel diameter depression

34‧‧‧Upper bearing

35‧‧‧O-ring

36‧‧‧ Cover

37‧‧‧ Positioning film

4‧‧‧ Guide slide

41‧‧‧ bottom wall

42‧‧‧立立

5‧‧‧Close door drive control mechanism

6‧‧‧ rod combination

61‧‧‧Pole

62‧‧‧Assistance wheel

63‧‧ ‧ stop pin

64‧‧‧Baffle

641‧‧‧ brake spring baffle face

642‧‧‧Close speed spring baffle face

65‧‧‧Support spring tube

66‧‧‧End plate

67‧‧‧ Screw locks

7‧‧‧煞车弹簧

71‧‧‧ Fixed end

72‧‧‧Free end

8‧‧‧Close speed spring

F1, F2‧‧‧ Elasticity

Other features and effects of the present invention will be apparent from the detailed description of the preferred embodiments of the drawings, wherein: FIG. 1 is a perspective view illustrating the application of the novel oil-free automatic door closer; The second figure is a perspective view showing the appearance structure of the new oil-free automatic door closer; the third figure is an exploded view of the three-dimensional part of the novel oil-free automatic door closer; and the fourth figure is the core structure of the novel oil-free automatic door closer The third figure is an exploded perspective view of the fourth figure; the sixth figure is a cross-sectional view along the VI-VI direction of the second figure, illustrating the internal implementation of the oil-free automatic door closer when the door leaf is closed; A cross-sectional view similar to the sixth drawing, illustrating an internal embodiment of the oil-free automatic door closer when the door leaf is opened to 30 degrees; and the eighth drawing is a cross-sectional view similar to the sixth and seventh figures, illustrating that the door is opened to At 90 degrees, the internal implementation of the oil-free automatic door closer.

Referring to the first to sixth figures, a preferred embodiment of the novel oil-free automatic door closer 1 is shown. In the first figure, the oil-free automatic door closer 1 controls the door leaf 12 to be closed in the manner of the door bow type door closer, so that it can cooperate with a joint mechanism 11 for the automatic closing operation of the door leaf 12. The two ends of the connecting mechanism 11 are connected to the oil-free automatic door closer 1 and the door leaf 12, which can be matched with the opening of the door leaf 12. And the corresponding rotation. However, the novel oil-free automatic door closer 1 can also be used as a ground hinge type door closer. In this state of use, the oil-free automatic door closer 1 is directly coupled with the door shaft of the door leaf 12 to control the door leaf 12 automatically. shut down. In the following description, the internal component composition of the oil-free automatic door closer 1 and the operational functions of the components will be described first, and then the overall operation mode of the oil-free automatic door closer 1 will be described.

Specifically, in terms of main components, the novel oil-free automatic door closer 1 includes a housing 2, a rotating mechanism 3, a guiding slide 4, and a closing driving force control mechanism 5.

The housing 2 is mounted on a fixture (here mounted on the door leaf 12) and includes a bottom housing 21, an outer cover 22, a base 23 and an upper cover 24. The base 23 is mainly housed in the rotating mechanism 3, the guide slide 4, and the door closing drive control mechanism 5, and the opening is closed by the upper cover 24. The bottom case 21 can receive the base 23, the upper cover 24, and other members therein, and is sealed by the outer cover 22. It should be noted that the above description of the structure of the casing 2 is only one embodiment of the novel oil-free automatic door closer. The user can adjust the configuration of the casing 2 as needed, and is not limited to the contents disclosed herein.

The rotating mechanism 3 is disposed in the housing 2 and mainly includes a shaft 31, a lower bearing 32, a cam 33, an upper bearing 34, an O-ring 35, a cover 36 and a positioning piece 37.

In an embodiment where the oil-free automatic door closer is used as the door bow type door closer, the shaft 31 of the rotating mechanism 3 is fitted to the above-mentioned member, which is disposed in the casing 2 and protrudes beyond the casing 2, And connected to the connecting mechanism 11, and can be coupled with the connecting mechanism 11 to drive each other. For example, when the user applies a force to open or close the door leaf 12, the shaft 31 is rotated by the link mechanism 11; when the user does not apply the door leaf 12, the shaft 31 can be driven by the door drive control mechanism 5 Rotating, and transmitting the driving force of closing the door to the door leaf 12 through the connecting mechanism 11, so that the door leaf 12 gradually becomes Turn off. And in the oil-free automatic door closer. In the embodiment of the ground hinge type door closer, the shaft 31 is directly connected to the door shaft of the door leaf 12, and can be rotated by the door leaf 12 to be closed by the rotation thereof.

The cam 33 of the rotating mechanism 3 is coupled to the bottom surface of the shaft 31 and pivoted about the shaft 31. In this embodiment, it is a symmetrical cam having an elliptical cross section and an outer edge at a corresponding short axis of the ellipse. There is a shortest wheel diameter 331 (as shown in the sixth figure), and each has a longest wheel diameter 332 at the long axis of the corresponding ellipse. In addition, the outer edge of the cam 33 of the embodiment is further recessed to form a short wheel diameter recessed portion 333 at the corresponding shortest wheel diameter 331, and concavely formed at the outermost edge corresponding to the longest wheel diameter 332. Wheel diameter recessed portion 334. Therefore, the short wheel diameter recessed portion 333 and the long wheel diameter recessed portion 334 of the cam 33 of the present embodiment are alternately distributed on the outer edge thereof, and the two short wheel diameter recessed portions 333 and the two long wheel diameter recessed portions 334 They are set at symmetrical positions.

The lower bearing 32 and the upper bearing 34 of the rotating mechanism 3 are both ball bearings, and the two sandwich the cam 33 to facilitate the smooth rotation of the cam 33. The O-ring 35 and the cover plate 36 are sequentially disposed on the upper bearing 34, which is an auxiliary member of the rotating mechanism 3. The positioning piece 37 is coupled to the aforementioned member, and the rotation mechanism 3 is fixed in the casing 2.

Therefore, according to the above-mentioned component composition, the rotating mechanism 3 can effectively transmit the door closing driving force generated by the door closing driving control mechanism 5 to the door shaft of the joint mechanism 11 or the door leaf 12 in a rotational manner, and the door leaf 12 is automatically closed.

The guiding slide 4 is mounted in the housing 2 and corresponds to the rotating mechanism 3, and includes a bottom wall 41 and two vertical walls 42 spaced apart from each other on the bottom wall 41, and can provide the door driving force control mechanism 5 during operation. Structure displacement guidance function.

The door drive control mechanism 5 is disposed in the casing 2 and includes a shaft assembly 6, a brake spring 7 and a door closing speed spring 8.

The rod assembly 6 includes a jack 61, a baffle 64, a support spring tube 65, an end plate 66 and a screw member 67.

The ejector pin 61 of the shank assembly 6 is movably disposed in the vertical wall 42 of the guide carriage 4 along its axial direction, one end of which is abutted against the outer edge of the cam 33 by the auxiliary wheel 62, and is interposed between the two The position of the upright wall 42 is also provided with a stop pin 63 projecting radially. The auxiliary wheel 62 can reduce the noise and damage caused by the friction when the jack 61 and the cam 33 are actuated; the stop pin 63 can limit the displacement of the jack 61 in the axial direction thereof to ensure the ejector 61 for a long time. It can also form a close fit with the cam 33 after the reciprocating slip.

The baffle 64 of the rod assembly 6 is disposed at the other end of the jack 61 where the auxiliary wheel 62 is not disposed, which is spaced apart from the guide carriage 4 and has a brake spring baffle surface facing the guide carriage 4. 641 and a closing speed spring baffle surface 642 of the guiding slide 4 apply an elastic force to the urging force of the ejector pin 61 for the brake spring 7 and the closing speed spring 8.

The support spring tube 65 of the rod assembly 6 is coupled to the closing speed spring baffle surface 642 of the baffle 64 and is located between the baffle 64 and the end plate 66 for the closing speed spring 8 to be placed thereon to avoid the closing speed spring. 8 Distorted or misaligned when actuated.

The end plate 66 of the rod assembly 6 is disposed in the casing 2 at a position corresponding to the baffle 64 and the closing speed spring 8 and spaced apart from the baffle 64 by a certain distance, and can be screwed to the supporting spring by the screw lock 67 The tube 65 can be adjusted by the screw lock depth of the screw lock 67 to adjust the distance between the shutter speed 64 to adjust the compression amount of the door closing speed spring 8, and control the elastic force of the door closing speed spring 8 and the closing of the door leaf 12. speed.

The brake spring 7 has a fixed end 71 and a free end 72 which is sleeved on the jack 61 and interposed between the guide slide 4 and the baffle 64, and the fixed end 71 is coupled to the guide slide seat The vertical wall 42 of 4 can provide a cushioning deceleration mechanism after the door leaf 12 is closed to a specific range (for example, within 30 degrees). The free end 72 of the brake spring 7 is not coupled to a particular configuration, which acts in the following paragraphs.

The closing speed spring 8 is disposed between the baffle 64 and the end plate 66, and the two ends are respectively coupled to the closing speed spring baffle surface 642 and the end plate 66 of the baffle 64, which constantly provide elastic force to the end plate 66, so that the top The rod 61 constantly urges the cam 33 along its axial direction, so that the outer edge of the cam 33 is pressed and correspondingly rotated, and the cam 33 tends to be brought back to the original position with its shortest wheel diameter 331 being connected with the jack 61. Therefore, it is possible to continuously supply the driving force required for its automatic closing after the door leaf 12 is opened.

As described in the foregoing paragraphs, the details and functions of the relevant components of the oil-free automatic door closer 1 of the present embodiment are well known. The following paragraphs will be accompanied by the relevant drawings to illustrate the overall operation of the oil-free automatic door closer 1.

Referring to the sixth figure, this is the internal configuration of the oil-free automatic door closer 1 when the door leaf 12 is in the closed state (the opening angle is 0 degrees). In this state, the shortest wheel diameter 331 of the outer edge of the cam 33 is in contact with the auxiliary wheel 62 of the jack 61. Although the cam 33 is biased by the plunger 61, it remains stationary and does not rotate. The portion of the closing speed spring 8 is at the maximum distance state due to the closing distance between the closing speed of the shutter 64 and the end plate 66 at this time, and the closing speed of the closing speed spring 8 is the smallest, so the closing speed spring 8 acts. The elastic force F1 (the direction in which the force direction is toward the cam 33) on the baffle 64 and the ejector pin 61 is also minimized. The portion of the brake spring 7 is at a minimum distance between the brake spring baffle face 641 of the baffle 64 and the upright wall 42 of the guide carriage 4, and the free end 72 of the brake spring 7 abuts against the block. The brake spring baffle face 641 of the plate 64, and the compression amount of the brake spring 7 is the largest, so that the brake spring 7 acts on the baffle 64 and the elastic force F2 of the jack 61 (the force direction is away from the convex The direction of the wheel 33 is the maximum state and offsets the partial elastic force F1 applied by the closing speed spring 8. Therefore, when the door leaf 12 is in the closed state, the total spring force (F2-F1) of the door closing speed spring 8 and the brake spring 7 applied to the jack 61 is at a minimum state.

Referring to the seventh figure, the internal configuration of the oil-free automatic door closer 1 is when the door leaf 12 is opened to a specific angle (the embodiment is set to 30 degrees). In this state, the brake spring 7 is at a critical point at which the elastic force F2 is elongated. Specifically, at this time, the boundary of the short wheel diameter recessed portion 333 of the cam 33 is in contact with the auxiliary wheel 62 of the jack 61, the cam 33 is in a rotatable state, and the compression amount of the brake spring 7 is exactly zero, so the criticality is The click brake spring 7 does not generate any elastic force F2 that restricts the movement of the shaft 31. At this critical point, if the user does not apply an external force to the door leaf 12, the elastic force (F1) of the door closing speed spring 8 will urge the jack 61 to press against the cam 33, so that the cam 33 gradually returns to its shortest wheel diameter 331 and The state in which the auxiliary wheels 62 of the jack 61 are in contact (as shown in the sixth figure). During this process, the rotation of the cam 33 is accompanied by the interlocking of the shaft 31, and the door leaf 12 can be gradually closed. While the door leaf 12 is gradually closed, the jack 61 gradually slides in the direction of the cam 33, so that the closing speed of the shutter 64 is gradually approached to the vertical wall 42 of the guide carriage 4, so the brake spring 7 The amount of compression and the elastic force F2 are gradually increased, and the offset effect of the elastic force F2 of the brake spring 7 is gradually increased, so that the speed at which the door leaf 12 is closed is gradually slowed, and a further door closing effect is provided. Therefore, during the recovery of the door leaf 12 from the specific opening angle (here, 30 degrees) to the fully closed state (0 degree), the elastic force F2 generated by the brake spring 7 is gradually increased, and the elastic force F1 generated by the closing speed spring 8 is gradually increased. It will gradually decrease, and the mechanism of this (F1) (F2) will cause the total elastic force (F1-F2) of the two to weaken rapidly, so that the driving force of the shaft 31 acting on the cam 33 is weakened, thus allowing the cam 33 The rotation slows down, and the closing speed of the door leaf 12 is gradually slowed down to achieve the purpose of buffering.

On the other hand, when the door leaf 12 is at the critical point (30 degrees) of the above opening, if the opening angle of the door leaf 12 is further increased, the shaft 31 will be slid away from the cam 33, and the brake spring 7 is The free end 72 is no longer in contact with the brake spring stop surface 641 of the baffle 64, so the compression amount of the brake spring 7 will continue to maintain zero compression, and the force F2 will also maintain a zero force, indicating the opening angle of the door leaf 12. Above this critical angle (30 degrees), the brake spring 7 no longer has a cushioning effect that slows the closing speed of the door leaf 12.

Referring to the eighth figure, this is the internal configuration of the oil-free automatic door closer 1 when the door leaf 12 is opened to a specific positioning angle (here, 90 degrees). At this time, the longest wheel diameter 332 of the outer edge of the cam 33 is in contact with the auxiliary wheel 62 of the jack 61, and the auxiliary wheel 62 of the jack 61 is just embedded in the long wheel diameter recessed portion 334 of the cam 33, so the cam 33 is subjected to The force applied by the jack 61 is maintained in a state of being stationary and not rotating if it is not subjected to a force applied by the user, so that the door leaf 12 is constantly maintained at its opening angle. In this state, since the closing distance between the spring shutter surface 642 and the end plate 66 of the shutter 64 is at the minimum distance state, the closing speed of the closing speed spring 8 is the largest, so the closing speed spring 8 acts on the shutter 64 and The elastic force F1 on the jack 61 is at the maximum state. The portion of the brake spring 7 has a spring force F2 of zero because its free end 72 is still not in contact with the brake spring stop surface 641 of the shutter 64. In this state, if the user applies the force to the door leaf 12, the auxiliary wheel 62 of the jack 61 is disengaged from the long wheel diameter recessed portion 334 of the cam 33, and the elastic force F1 provided by the door closing speed spring 8 is the maximum state, the door leaf 12 The initial closing speed will be the fastest when the door is automatically closed from 90 degrees. When the opening angle of the door leaf 12 is gradually decreased, the elastic force F1 provided by the door closing speed spring 8 is also gradually reduced, and the door closing speed of the door leaf 12 is slowed down.

Therefore, in combination with the descriptions of the sixth to eighth figures described above, according to the different opening angles of the door leaf 12, the oil-free automatic door closer 1 will provide an automatic closing, closing buffer or setting. Bit effect. When the 90 degree is turned on, the oil-free automatic door closer 1 maintains the door leaf 12 at 90 degrees. When the opening angle of the door leaf 12 is between 30 degrees and 90 degrees, the door closing speed spring 8 provides the elastic driving force F1 required for the door leaf 12 to be closed, and the elastic driving force F1 gradually decreases as the opening angle of the door leaf 12 decreases. The closing speed of the door leaf 12 is gradually slowed down. When the opening angle of the door leaf 12 is between 0 degrees and 30 degrees, the elastic drive force F1 required for the door closing speed spring 8 to provide the door leaf 12 to be closed is gradually decreased as the opening angle of the door leaf 12 is decreased, and the brake spring 7 is in this state. A reverse drive force F2 opposite to the elastic force F1 is further provided, and the reverse drive force F2 is gradually increased as the opening angle of the door leaf 12 is decreased, so that the closing speed of the door leaf 12 is more slow, providing a cushioning effect.

On the other hand, in the novel oil-free automatic door closer 1, according to the symmetrical shape design of the cam 33, the angle at which the door leaf 12 is opened can be further increased between 90 degrees and 180 degrees, or reversely opened to -180 degrees. The oil-free automatic door closer 1 can provide automatic closing, automatic positioning and door closing buffer at each opening angle. In addition, in the application mode as the ground hinge, the bottom end of one side of the door leaf 12 can be directly coupled to the shaft 31 to generate linkage without using the connection mechanism 11. In addition, the novel oil-free automatic door closer 1 has the advantages of small volume, low cost, no oil and environmental protection, high safety in use, low failure rate, and easy installation, so the purpose of the present invention can be achieved.

However, it should be particularly noted that the above-mentioned changes in the operating mechanism of the door leaf 12 at a specific opening angle (for example, 30 degrees, 90 degrees) may be adjusted according to actual needs, for example, the user may design by the shape of the cam, brake the spring 7 and close the door. The adjustment of the compression amount of the speed spring 8 changes the critical angle of the change of the operating mechanism (for example, it can be changed from 30 degrees to 45 degrees), so the above content is only used to explain the embodiment of the embodiment, and the present invention should not be limited thereby. Scope of implementation The simple equivalent changes and modifications made by the scope of the present patent application and the contents of the patent specification are still within the scope of the present patent.

1‧‧‧ Oil-free automatic door closer

2‧‧‧Shell

21‧‧‧ bottom case

22‧‧‧ Cover

23‧‧‧ Pedestal

24‧‧‧Upper cover

31‧‧‧ shaft

37‧‧‧ Positioning film

61‧‧‧Pole

7‧‧‧煞车弹簧

8‧‧‧Close speed spring

Claims (6)

An oil-free automatic door closer for automatically closing a door. The oil-free automatic door closer comprises: a casing mounted on a fixed object; a rotating mechanism comprising a shaft and a cam, the shaft is mounted Provided in the housing and driven by the rotation of the door; the cam is coupled to the shaft and pivoted about the shaft, and the outer edge has at least one shortest wheel diameter and at least one longest wheel diameter. And forming a short wheel diameter recessed portion corresponding to the shortest wheel diameter; a guiding slide seat installed in the housing and corresponding to the cam; and a door driving force control mechanism mounted on the shell The body includes a rod body assembly having a top rod, a baffle plate and an end plate. The jack rod is movably disposed in the guide slide seat along the axial direction thereof, and one end thereof abuts against the cam The baffle is disposed at the other end of the ram, and is spaced apart from the guiding slide, and has a braking spring baffle surface of the guiding sliding seat and a back sliding guide a closing speed spring baffle surface of the seat; the end plate is disposed in the housing, and its setting position The baffle should be spaced apart from the baffle by a distance; a brake spring having a fixed end and a free end sleeved on the jack and between the guide slide and the baffle And the fixing end is coupled to the guiding slide; and a closing speed spring is disposed between the baffle and the end plate, and the two ends are respectively coupled to the closing speed spring baffle surface of the baffle and the end a plate, wherein, when the door leaf is closed, the shortest wheel diameter of the outer edge of the cam is in contact with the ejector pin; when the door leaf is opened, the door closing speed spring constantly provides an elastic force to the end plate, so that the ejector pin tends to Abutting the cam axially, causing the cam to rotate and tending to contact the ram at its shortest wheel diameter; When the door leaf is opened and the short wheel diameter recessed portion of the cam is in contact with the jack rod, the free end of the brake spring will abut against the brake spring baffle surface of the baffle plate to offset the spring speed of the door closing speed spring Part of the elastic force. The oil-free automatic door closer according to claim 1, wherein the cam is a symmetrical cam, and the cross section is substantially elliptical, and the outer edge has a shortest wheel diameter at a short axis corresponding to the ellipse, and Corresponding to the long axis of the ellipse, respectively, having a longest wheel diameter, and respectively forming a long wheel diameter concave portion corresponding to the longest wheel diameter; when the door leaf is opened to a specific angle, the long wheel diameter of the cam The recess is in contact with the jack so that the cam tends not to rotate. The oil-free automatic door closer according to claim 1, wherein the end plate is disposed in the housing in an adjustable position, and a specific separation distance between the end plate and the baffle causes the closing speed The spring provides a corresponding elastic force. The oil-free automatic door closer according to claim 1, wherein the rod assembly further has a support spring tube coupled to the baffle and located between the baffle and the end plate for closing the door The speed spring is sleeved on it. The oil-free automatic door closer according to claim 4, wherein the rod assembly further has a screw member for screwing the end plate to the support spring tube, and the end plate can be adjusted The distance from the baffle. The oil-free automatic door closer according to claim 1, wherein the guide slide comprises a bottom wall and two vertical walls spaced apart from each other, the vertical wall for the top rod to be movable along the axial direction thereof The ram further has a stop pin protruding radially, the stop pin being located between the two vertical walls of the guide slide to limit the displacement of the ram in the axial direction thereof .