Door closer

Abstract

To provide a door closer which is excellent in operability of a door and can operate the door as intended even in consideration of various variations.SOLUTION: A door closer (100) that biases a rotating door in a closing direction includes a rotary shaft (3) that is rotatable about a central axis (O) in a vertical direction and rotates from an open position where the door is open to a closed position where the door is closed, a cam (4) that rotates together with the rotary shaft (3), a slider (7) that is horizontally movable and has a tip end portion (9) in contact with an 4b of an outer peripheral portion of the cam (4), and a spring member (13) that applies a resilient force to the slider (7) to press the tip end portion (9) against the 4b of the outer peripheral portion. The outer peripheral portion 4b relates to a rotation angle when the cam 4 rotates around the central axis O and a radius from the central axis O to the outer peripheral portion 4b, and a change amount of the radius for each predetermined range in the rotation angle is constant.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a door closer. [Background technology]

[0002] BACKGROUND ART A door closer that automatically closes a rotating door by biasing the door in the closing direction is known, for example, as disclosed in Patent Document 1.

[0003] The door closer in Patent Document 1 includes a shaft that rotates in response to the door opening and closing operation via a connecting mechanism, a cam that rotates together with the shaft, a brake spring that biases the apex rod to press the auxiliary wheel against the outer periphery of the cam, and a door closing speed spring that applies an elastic force to the apex rod in the opposite direction to that of the brake spring. The outer periphery of the cam described above is elliptical, with the major radius approximately twice the minor radius. When the door is closed, the auxiliary wheel contacts the outer edge of the minor radius, and when the door is fully open, the auxiliary wheel contacts the outer edge of the major radius. The door closing speed spring is configured not to apply an elastic force to the apex rod when the door is fully open, but to apply an elastic force as the door is closing.

[0004] According to Patent Document 1, by using the above door closer, the door moves at the fastest speed when it starts moving from a fully open position, and then the speed gradually slows down, and when the door close speed spring comes into effect, the door speed slows down further, providing a buffering effect. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Utility Model Registration No. 3189994 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, the door closer in Patent Document 1 changes the door speed depending on the angle at which the door opens. However, for example, the sliding resistance between moving parts varies due to various factors (such as variations in the dimensions of each part and their positions during assembly), making it difficult to operate the door at the intended speed. In particular, the door closer in Patent Document 1 uses two springs, and the elastic forces of each spring act in opposite directions. Furthermore, the elastic force of one spring acts only during the closing process of the door. This makes it difficult to exert the intended elastic force with these springs, and therefore makes it difficult to adjust the door speed. Moreover, because the speed slows as the door closes, it is possible that the door may not be completely closed due to various variations.

[0007] Furthermore, the door closer of Patent Document 1 increases the elastic force acting on the cam when the door speed is increased, and decreases the elastic force acting on the cam when the door speed is decreased, and the torque around the central axis of the cam changes significantly, so the amount of force required for the user to open the door changes significantly. This door closer is configured so that the door speed is fastest when the door starts moving from a fully open state and then gradually slows down, so when opening a door using this door closer, the user must increase the force they apply to the door as the door opens further, which creates difficulties in terms of door operability.

[0008] In view of the above, an object of the present invention is to provide a door closer that not only has excellent door operability but also allows the door to operate as intended even when various variations are taken into consideration. [Means for solving the problem]

[0009] The present invention is a door closer that biases a rotating door in the closing direction, and comprises: a rotating shaft that is rotatable around a vertical central axis in response to the rotation of the door and rotates from an open position where the door is open to a closed position where the door is closed; a cam that rotates together with the rotating shaft; a slider that is movable horizontally and whose tip end contacts the outer periphery of the cam; and a spring member that imparts elastic force to the slider to press the tip end against the outer periphery, wherein the outer periphery has a rotation angle when the cam rotates around the central axis and a radius from the central axis to the outer periphery, and the amount of change in the radius is constant for each predetermined range of the rotation angle. [Effects of the Invention]

[0010] After extensive research using a door closer with the above configuration, it was found that it was possible to suppress changes in the torque of the cam that rotates around the central axis. In other words, the door closer of the present invention can suppress changes in the force required to open the door, resulting in excellent door operability. Furthermore, since fluctuations in the torque required to close the door are suppressed even when the door angle changes, the door closing speed can be kept approximately constant regardless of the door opening angle. Furthermore, since the structure is simpler and there are fewer factors that cause variation compared to conventional door closers that use two springs, the door can be operated as intended even when various variations are taken into account. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a perspective view of a door closer according to an embodiment of the present invention; [Figure 2] FIG. 2 is an exploded perspective view of the door closer shown in FIG. 1. [Figure 3] FIG. 2 is a cross-sectional view taken along line AA shown in FIG. [Figure 4A] FIG. 10 is an explanatory diagram relating to the torque of the cam and the outer periphery of the cam. [Figure 4B] FIG. 4B is a partially enlarged view of FIG. 4A, illustrating the torque of the cam. [Figure 4C]FIG. 4B is a partially enlarged view of FIG. 4A, illustrating the torque of the cam. [Figure 4D] FIG. 4B is a partially enlarged view of FIG. 4A, illustrating the torque of the cam. [Figure 4E] FIG. 4B is a partially enlarged view of FIG. 4A, illustrating the outer periphery of the cam. [Figure 5A] This is a diagram showing the state where the rotation angle is 0° for a cam with Δr of 1.0. [Figure 5B] This is a diagram showing the state of a cam with Δr of 1.0 when the rotation angle is 45°. [Figure 5C] This is a diagram showing the state of a cam with Δr of 1.0 when the rotation angle is 90°. [Figure 6] 10 is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when a cam with Δr of 0.5 and four types of spring members with different spring constants are used. [Figure 7] 10 is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when a cam with Δr of 1.0 and four types of spring members with different spring constants are used. [Figure 8] 10 is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when a cam with Δr1.5 and four types of spring members with different spring constants are used. [Figure 9] 10 is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when a cam with Δr of 2.0 and four types of spring members with different spring constants are used. [Figure 10] 10 is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when a cam with Δr of 0.5 to 2.0 and a spring member with a spring constant of 1.96 N / mm is used, using actual measured values. [Figure 11A] 10 is a diagram showing a state in which the rotation angle of the cam is 0° in an embodiment in which the central axis is offset from the movement trajectory of the tip portion. FIG. [Figure 11B] 10 is a diagram showing an embodiment in which the central axis is offset from the movement trajectory of the tip portion, and shows a state in which the cam has a rotation angle of 90°. FIG. [Figure 12A]10 is a diagram showing an embodiment in which a small diameter portion is provided on the outer periphery of the cam, showing a state in which the cam has a rotation angle of 130°. FIG. [Figure 12B] 10 is a diagram showing an embodiment in which a small diameter portion is provided on the outer periphery of the cam, showing a state in which the rotation angle of the cam is 0°. FIG. [Figure 13] 12C is a graph showing the relationship between the rotation angle of the cam and the torque of the cam about the central axis when the cam shown in FIGS. 12A and 12B is used. DETAILED DESCRIPTION OF THE INVENTION

[0012] A door closer according to one embodiment of the present invention will be described below with reference to the accompanying drawings. The drawings shown in the accompanying drawings are schematic, and the thickness and width of each part, the ratio between each part, etc. may differ from those actually implemented. For convenience, the following description will be given in the direction shown in the accompanying drawings. The direction from "left" to "right" shown in the drawings may be described as "forward," and the opposite direction as "reverse."

[0013] 1 to 3 are diagrams showing a door closer 100 according to an embodiment of the present invention. First, the configuration of the door closer 100 will be described with reference to the drawings.

[0014] The door closer 100 includes a case 1, a plate 2, a rotating shaft 3, a cam 4, a first spacer 5, a second spacer 6, a slider 7, a slider shaft 8, a bearing 9, a bearing shaft 10, a first guide 11, a second guide 12, a spring member 13, an adjustment bolt 14, a positioning shaft 15, a cover 16, a link 17, a washer 18, as well as screws and the like used to attach these components. The bearing 9 corresponds to the "tip" of the slider in this specification.

[0015] The case 1 is a component attached to a door that is rotatably supported relative to, for example, an opening in a building. The case 1 of this embodiment is cylindrical with a bottom and rectangular in plan view, and has a through-hole 1a on its side for fixing the case 1 to the door. The case 1 is fixed to the side of the door by inserting a screw or the like into the through-hole 1a and tightening the screw or the like against the door. The left side of the case 1 is provided with a female threaded portion 1b into which an adjustment bolt 14 screws.

[0016] 2, the plate 2 is formed by bending, for example, a thin metal plate as shown in the figure, with openings or the like formed at the positions shown. The plate 2 of this embodiment includes a plate main body portion 2a located at the bottom, an upper support portion 2b located above the plate main body portion 2a and spaced apart from the plate main body portion 2a in the vertical direction, and a pair of guide support portions 2c located to the left of the upper support portion 2b and spaced apart from each other on the front and rear sides. As shown in the figure, the plate main body portion 2a and the upper support portion 2b are provided with circular through-holes 2d, and the pair of guide support portions 2c are provided with recesses 2e that cut out the upper ends of the guide support portions 2c facing downward.

[0017] The rotating shaft 3 is a cylindrical member centered on a central axis O. The rotating shaft 3 includes a disk-shaped large-diameter portion 3a that supports the cam 4 from below, a cylindrical lower shaft portion 3b located below the large-diameter portion 3a, a central shaft portion 3c located above the large-diameter portion 3a and having a circular outer periphery with two parallel flat surfaces extending in the axial direction (a so-called H-cut shape), and a tip portion 3d located above the central shaft portion 3c and having a smaller diameter than the central shaft portion 3c. The upper end of the tip portion 3d is shaped such that the circular outer periphery has two parallel flat surfaces extending in the axial direction. Note that in this embodiment, the central shaft portion 3c and the tip portion 3d are shaped such that the two parallel flat surfaces are provided to hold other components in a rotation-preventing manner. However, the rotation-preventing function may be achieved by other configurations (for example, a D-shape with a circular outer periphery with one flat surface extending in the axial direction). An internal thread is provided on the top surface of the shaft tip 3d to be used when attaching the link 17 to the rotating shaft 3. When assembled into the door closer 100, the rotating shaft 3 can rotate in a direction that revolves around a central axis O (see Figure 1) that is oriented vertically.

[0018] The cam 4 is a relatively thick plate, and has an insertion hole 4a in its center that corresponds to the outer shape of the shaft center portion 3c. That is, when the shaft center portion 3c is inserted into the insertion hole 4a and the rotary shaft 3 is attached to the cam 4, the cam 4 is prevented from rotating relative to the rotary shaft 3 and rotates together with the rotary shaft 3. The cam 4 also has an outer peripheral portion 4b located on the outer periphery. The detailed configuration of the outer peripheral portion 4b will be described later.

[0019] The first spacer 5 has a shape that combines a cylindrical portion and a ring-shaped portion, and is a member that supports the upper portion of the rotating shaft 3. When assembling the first spacer 5 of this embodiment using the procedure described below, the first spacer 5 is fixed to the plate 2 with a screw or the like in a state where the shaft tip portion 3d is inserted.

[0020] The second spacer 6 is a ring-shaped plate-shaped member that supports the lower part of the rotating shaft 3. The second spacer 6 of this embodiment supports the lower part of the rotating shaft 3 by inserting the lower shaft part 3b into the inside thereof.

[0021] In this embodiment, the slider 7 is made up of a slider shaft 8, a bearing 9, and a bearing shaft 10.

[0022] The slider shaft 8 comprises a cylindrical slider shaft main body 8a and a pair of bearing support parts 8b located at the tip end of the slider shaft main body 8a and spaced apart in the vertical direction. As shown in Figure 2, the cross-sectional shape of the pair of bearing support parts 8b at their base is such that the upper and lower parts extend linearly from the front to the back, while the front and back parts extend in an arc. A through-hole is provided at the tip end of the bearing support part 8b, passing through the bearing support part 8b in the vertical direction.

[0023] The bearing 9 is a ring-shaped inner ring and an outer ring between which a plurality of spherical bodies are arranged, and it is possible to rotate the outer ring relative to the inner ring with little resistance.

[0024] The bearing shaft 10 is held by the slider shaft 8 by being inserted into the through hole provided in the bearing support portion 8b and into the inside of the inner ring of the bearing 9, with the bearing 9 disposed between the pair of bearing support portions 8b.

[0025] In this embodiment, the first guide 11 is shaped like a rectangular parallelepiped and has an insertion hole 11a in its center through which the slider shaft 8 is inserted. As shown in Fig. 2, the opening shape of the insertion hole 11a at the right end of the first guide 11 corresponds to the shape of the base of the bearing support portion 8b of the slider shaft 8, with the upper and lower ends extending linearly from the front to the back, and the front and back ends extending in an arc shape. The first guide 11 has protrusions 11b on its front and back sides that fit into recesses 2e of the plate 2.

[0026] In this embodiment, the second guide 12 has an outer shape with a cylindrical portion at the tip of a rectangular parallelepiped portion, and a through-hole located inside the cylindrical portion extends to the inside of the rectangular parallelepiped portion. Here, the cylindrical portion is referred to as a guide tube 12a, and a circular hole provided inside the guide tube 12a is referred to as a guide hole 12b. The guide tube 12a can be inserted into the insertion hole 11a as shown in FIG. 3. The slider shaft main body 8a can be inserted into the guide hole 12b.

[0027] In this embodiment, the spring member 13 is a coil spring made of a wire wound in a spiral shape so that the cross section of the spring member 13 is circular, and when compressed to shorten its length, it generates an elastic force that causes it to return to its original length. The spring member 13 can have a predetermined spring constant by appropriately selecting, for example, the wire diameter of the wire used, the outer diameter of the spring member 13, the length of the spring member 13, etc.

[0028] The adjustment bolt 14 is a member that screws into a female thread portion 1b provided in the case 1. As will be described later, the adjustment bolt 14 has a function of adjusting the elastic force of the spring member 13 by moving the second guide 12.

[0029] In this embodiment, the positioning shaft 15 is cylindrical, and is inserted into a through-hole provided in the plate 2 and held by the plate 2. The positioning shaft 15 has the function of restricting the rotation of the cam 4 within a predetermined range.

[0030] The cover 16 covers the upper side of the case 1 and is attached to the case 1. The cover 16 of this embodiment can be attached to the case 1 using a plurality of screws or the like.

[0031] One end of the link 17 is attached to the shaft tip 3d of the rotating shaft 3, and the other end is attached to a door (not shown) or another link connected to the door. One end of the link 17 is provided with a through hole whose shape matches the outer shape of the shaft tip 3d.

[0032] The washer 18 is used when attaching the link 17 to the rotating shaft 3. As described above, a female thread is provided on the upper surface of the shaft tip 3d, and the link 17 can be attached to the rotating shaft 3 by tightening a screw into the female thread with the link 17 and the washer 18 overlapping on the upper surface of the shaft tip 3d.

[0033] Such components can be assembled, for example, by the following procedure: Note that the following explanation is merely an example, and the order of steps can be changed as appropriate.

[0034] First, the cam 4 is placed between the plate main body 2a and the upper support part 2b. Then, the rotating shaft 3 is inserted from below into the through hole 2d of the plate main body 2a, and the rotating shaft 3 is further inserted through the insertion hole 4a provided in the cam 4 and the through hole 2d provided in the upper support part 2b. Then, with the cam 4 moved upward, the second spacer 6 is inserted between the cam 4 and the plate main body 2a, and the lower shaft part 3b of the rotating shaft 3 is inserted into the second spacer 6. Next, the first spacer 5 is inserted onto the rotating shaft 3 from above the plate 2, and the first spacer 5 is fixed to the plate 2 with a screw or the like. In this state, the insertion hole 4a of the cam 4 is inserted into the shaft center part 3c of the rotating shaft 3, so that the cam 4 is prevented from rotating relative to the rotating shaft 3.

[0035] 3, the bearing support portion 8b of the slider shaft 8 is inserted into the insertion hole 11a of the first guide 11 so that the bearing support portion 8b protrudes from the first guide 11. As described above, the shape of the insertion hole 11a corresponds to the shape of the base of the bearing support portion 8b, and the two portions extend linearly upward and downward. Therefore, the slider shaft 8 is supported relative to the first guide 11 so as to be prevented from rotating and to slide only in the forward and backward directions. Next, a bearing 9 is placed between the pair of bearing support portions 8b, and a bearing shaft 10 is inserted into a through hole provided in the bearing support portions 8b and into the inner ring of the bearing 9. Thereafter, a spring member 13 is inserted into the slider shaft main body 8a, and the slider shaft main body 8a is inserted into the guide tube 12a of the second guide 12. The guide tube 12a is then inserted into the insertion hole 11a of the first guide 11. 2, the protrusion 11b of the first guide 11 is fitted into the recess 2e of the plate 2, and these members are attached to the plate 2. Furthermore, the positioning shaft 15 is inserted into the through-hole provided in the plate 2 and attached to the plate 2.

[0036] Thereafter, the plate 2 with the various components attached is attached to the inside of the case 1. Then, the adjustment bolt 14 is screwed into the female thread portion 1b and attached to the case 1. The tip of the adjustment bolt 14 attached to the case 1 comes into contact with the left end of the second guide 12, as shown in FIG.

[0037] Next, cover 16 is attached to case 1 using a plurality of screws or the like. Then, with one end of link 17 and washer 18 placed on the upper surface of shaft tip 3d of rotating shaft 3, the link 17 is attached to the rotating shaft 3 by tightening the screw into the female threaded portion provided on the upper surface of shaft tip 3d. As described above, the upper end of shaft tip 3d has a shape provided with two parallel flat surfaces extending in the axial direction, and one end of link 17 has a through-hole with a shape corresponding to the upper end of shaft tip 3d, so that link 17 is prevented from rotating with respect to the rotating shaft 3.

[0038] In the door closer 100 assembled in this manner, the rotating shaft 3 is supported rotatably in a direction revolving around a central axis O oriented vertically, as shown in FIG. 1. When the door closer 100 is attached to a door rotatably supported relative to an opening in a building, for example, the rotating shaft 3 can rotate from an open position in which the door is open relative to the opening to a closed position in which the opening is closed. The slider shaft 8 is supported by a first guide 11 and a second guide 12 so as to slide only in the front-to-rear direction (the left-to-right direction in FIGS. 1 to 3). As shown in FIG. 3, one end of the spring member 13 is supported by a guide tube 12a of the second guide 12, and the slider shaft 8 is biased in a forward direction by the other end of the spring member 13. Therefore, the outer ring of the bearing 9 is pressed against the outer circumferential portion 4b of the cam 4 by the elastic force of the spring member 13, while being rotatable around the axis of the bearing shaft 10 relative to the slider shaft 8 and movable only in the front-to-rear direction. In the door closer 100 of this embodiment, the adjustment bolt 14 is threaded into the female thread portion 1b of the case 1, so when the adjustment bolt 14 is rotated relative to the case 1, the adjustment bolt 14 moves in the front-to-rear direction relative to the case 1 in the state shown in Fig. 3. The tip of the adjustment bolt 14 is in contact with the second guide 12, and the second guide 12 moves in the front-to-rear direction in response to the rotation of the adjustment bolt 14, so the elastic force of the spring member 13 applied to the slider shaft 8 can be changed.

[0039] Here, we will explain in detail the outer circumferential portion 4b of the cam 4. Figures 4A to 4E are diagrams that schematically show the configuration related to the periphery of the cam 4, with Figure 4A being an overall view of the periphery of the cam 4, Figures 4B to 4D being enlarged views of a portion of Figure 4A, and Figure 4E being a further enlarged view of a portion of Figure 4A.

[0040] In the cam 4 of this embodiment, the outer peripheral portion 4b is configured such that, when the bearing 9 is pressed against the outer peripheral portion 4b by the elastic force of the spring member 13, a torque is applied to rotate the cam 4 about the central axis O from the open position to the closed position while the rotary shaft 3 rotates from the open position where the door is open to the closed position where the door is closed. The direction of rotation of the cam 4 from the open position to the closed position shown in FIG. 4A is counterclockwise, as indicated by the arrow in the figure. In addition, in a plan view, the central axis O of the cam 4 in this embodiment is located on the same line as the movement locus of the center of the bearing 9, which moves in the front-to-rear direction as shown in FIG. 4B.

[0041] Here, the torque acting on the cam 4 will be described. The point where the outer ring of the bearing 9 is pressed against the outer circumferential portion 4b by the elastic force of the spring member 13 at a certain point in time is defined as contact point P1. Because the elastic force of the spring member 13 acts from the rear to the front, a force (indicated by symbol F in FIG. 4B) also acts from the rear to the front at contact point P1, as shown in FIG. 4B. If the tangent line between the outer circumferential portion 4b and the outer ring of the bearing 9 at contact point P1 (in other words, the normal line to the line connecting the center of the bearing 9 and contact point P1) is defined as tangent line L1, the component of this force F in the direction of tangent line L1 is shown as force F1 in FIG. 4B. Of this force F1, the force acting as torque around the central axis O of the cam 4 is a force directed along line L3, where L2 is the line connecting the central axis O of the cam 4 to contact point P1 in a plan view, as shown in FIG. 4C, and line L3 is the normal line to line L2 at contact point P1. Here, as described above, the slider shaft 8 equipped with the bearing 9 is supported so as to slide only in the front-rear direction relative to the first guide 11 (it does not move in any other direction). Therefore, when the component force of the force F1 shown in FIG. 4C acting along the straight line L3 is defined as force F2, a force that is a reaction force of the force F2 (force F3 having the same magnitude as force F2 but in the opposite direction as shown in FIG. 4D) acts on the cam 4. That is, the torque of the cam 4 around the central axis O at the contact point P1 is calculated by multiplying the length from the central axis O to the contact point P1 in a plan view by the force F3 at the contact point P1, and this torque causes the cam 4 to rotate in the direction in which the force F3 shown in FIG. 4D acts (i.e., counterclockwise rotation as shown in FIG. 4A). Therefore, by using the door closer 100 of this embodiment, the door is biased in the closing direction.

[0042] Furthermore, in this embodiment, the outer peripheral portion 4b is formed so that the amount of change in radius from the central axis O to the outer peripheral portion 4b is constant for each predetermined range of rotation angle when the cam 4 rotates around the central axis O. This point will be described in detail with reference to FIGS. 4A and 4E. In FIGS. 4A and 4E, the point at which the outer ring of the bearing 9 is pressed against the outer peripheral portion 4b at a certain point by the elastic force of the spring member 13 is designated as contact point P1. The radius from the central axis O to the outer peripheral portion 4b at contact point P1 is designated as radius R. As shown in FIG. 4A, when the cam 4 rotates counterclockwise around the central axis O by a predetermined angle θ (10°, for example), the contact point between the outer peripheral portion 4b and the outer ring of the bearing 9 is designated as P2, and when the cam 4 further rotates counterclockwise by a predetermined angle θ, the contact point between the outer peripheral portion 4b and the outer ring of the bearing 9 is designated as P3. In this case, the outer peripheral portion 4b of this embodiment is formed so that when the rotary shaft 3 rotates from contact point P1 to contact point P2 at an angle θ, the radius from the central axis O to contact point P2 is smaller by Δr than the radius R from the central axis O to contact point P1. When the rotary shaft 3 rotates from contact point P2 to contact point P3 at an angle θ, the radius from the central axis O to contact point P3 is smaller by Δr than the radius from the central axis O to contact point P2. The outer peripheral portion 4b is shaped so that this relationship is satisfied while the rotary shaft 3 rotates from the open position where the door is open to the closed position where the door is closed.

[0043] The inventors of the present application have conducted extensive studies using the door closer 100 having such a configuration and have confirmed that it is possible to suppress changes in the torque around the central axis O acting on the cam 4. Below, some of the results of the inventors' studies will be described.

[0044] First, we will explain the relationship between the rotation angle of the cam 4 when it rotates around the central axis O and the torque of the cam 4 around the central axis O at the contact point where the bearing 9 contacts the cam 4 at that rotation angle. FIGS. 5A to 5C are diagrams for explaining the rotation angle of the cam 4. The illustrated cam 4 is formed so that the angle θ for each predetermined range described with reference to FIGS. 4A and 4E is 10°, and the change in radius Δr for each angle θ is 1.0 mm. FIG. 5A shows the position of the cam 4 when the door is closed (the state in which the cam 4 is in the closed position), and the rotation angle of the cam 4 at this time is defined as 0°. FIG. 5B shows the position of the cam 4 when the door is opened 45°. The rotary shaft 3 and cam 4, which rotate in conjunction with the door, have rotated 45° clockwise from the state shown in FIG. 5A. In other words, FIG. 5B shows the state in which the rotation angle of the cam 4 is 45°. Figure 5C shows the posture of cam 4 (cam 4 is in the open position) when the door is open (a state in which the closed door has been rotated 90 degrees), and the rotary shaft 3 and cam 4, which rotate in conjunction with the door, have rotated 90 degrees clockwise from the state shown in Figure 5A. In other words, Figure 5C shows the state in which the rotation angle of cam 4 is 90 degrees.

[0045] 6 to 9 are diagrams showing some of the results of confirmation using an analytical model of the door closer 100. The analytical model used was similar to that shown in FIGS. 5A to 5C, and the amount of change in radius Δr at the outer circumferential portion 4b of the cam 4 per predetermined angle θ (10° in this embodiment) and the spring constant of the spring member 13 were changed. In the confirmation, the torque around the central axis O of the cam 4 at the contact point was calculated for each of the cases where the rotation angle of the cam 4 was 10°, 50°, and 80°. The top graph in FIG. 6 shows the results using an analytical model in which the amount of change in radius Δr per predetermined angle was 0.5 mm and the spring constant of the spring member 13 was 1.96 N / mm. The value on the X axis is the rotation angle of the cam 4 (unit: °), and the value on the Y axis is the torque around the central axis O of the cam 4 at the contact point (unit: N·mm). As can be seen from this graph, when the change in radius Δr per given angle θ is 0.5 mm and the spring constant of the spring member 13 is 1.96 N / mm, even when the rotation angle of the cam 4 varies between 10° and 80°, the torque around the central axis O of the cam 4 at the contact point is maintained at approximately 100 N·mm, indicating that torque changes in the cam 4 are sufficiently suppressed. Furthermore, when a linear approximation curve was calculated using the least squares method for the rotation angle of the cam 4 and the torque around the central axis O of the cam 4 at the contact point, the result was y = 0.0993x + 89.114. As will be described later, a slope of this linear approximation curve between -0.5 and 2 is advantageous for suppressing torque changes in the cam 4 in an actual door closer 100. Regarding this point, when an actual door closer 100 was tested using this analytical model with a slope of 0.0993, it was confirmed that torque changes in the cam 4 were also suppressed in this door closer 100.

[0046] 6 show the results of using the same analytical model as the first analytical model described above, except that the spring constant of the spring member 13 was changed to 0.98 N / mm, 0.49 N / mm, and 0.225 N / mm. These results also show that the change in torque in the cam 4 is sufficiently suppressed.

[0047] 7 to 9 show the results of using the same analytical model as shown in Fig. 6, except that the amount of change in radius Δr per predetermined angle θ is changed to 1.0 mm, 1.5 mm, and 2.0 mm. As is clear from Figs. 6 to 9, the smaller the amount of change in radius Δr per predetermined angle θ, the smaller the slope of the linear approximation curve obtained by the least squares method tends to be, and it can be seen that changes in torque in cam 4 can be more effectively suppressed by reducing the amount of change in radius Δr per predetermined angle θ. The advantageous range of the amount of change in radius Δr per predetermined angle θ will be described later.

[0048] Based on the results of these analytical models, verification was also performed on an actual door closer 100. Some of the results are shown in FIG. 10. FIG. 10 shows the results when the spring constant of the spring member 13 is 1.96 N / mm and the cam 4 is used, with the radius change Δr set to 0.5 mm, 1.0 mm, 1.5 mm, and 2.0 mm per predetermined angle θ (10° in this embodiment), starting from the top graph. In each graph, the value on the X axis represents the rotation angle of the cam 4 (unit: °), and the value on the Y axis represents the torque (unit: N·mm) about the central axis O of the cam 4 at the contact point. The torque of the cam 4 was measured each time the rotation angle of the cam 4 was changed. In the verification, the torque was measured each time the angle of the cam 4 was changed, starting from when the rotation angle of the cam 4 was 0°. After the rotation angle of the cam 4 reached 90°, the torque was measured again until the rotation angle of the cam 4 reached 0°. Each graph in FIG. 10 also shows a linear approximation curve obtained by the least squares method for the torque of the cam 4 as the rotation angle of the cam 4 changes from 0° to 90°.

[0049] We checked other door closers 100, including the door closer 100 shown in Figure 10, in which the change in radius Δr per predetermined angle θ at the outer periphery 4b of the cam 4 and the spring constant of the spring member 13 were changed. When the slope of the linear approximation curve calculated by the least squares method for the rotation angle of the cam 4 and the torque about the central axis O of the cam 4 at the contact point, calculated using the analytical model, exceeded 2, it was found that the torque of the cam 4 increased as the rotation angle of the cam 4 approached 90°, which tended to affect the operability of the door. Furthermore, if this slope became larger in the negative direction, the torque of the cam 4 for biasing the door in the closing direction decreased, which may affect the performance of the door closer 100. Based on these findings, further investigations confirmed that it is advantageous for the slope of the linear approximation curve calculated by the least squares method to satisfy the relationship of -0.5 to 2.

[0050] Considering that it is advantageous for the gradient of the linear approximation curve obtained by the least squares method to be between -0.5 and 2, it can be said that it is preferable for the change in radius Δr per predetermined angle θ described with reference to Figures 6 to 9 to be 1.0 mm or less, because the gradient may exceed 2 when the angle θ is 1.5 mm or more.

[0051] As shown in FIG. 4B, the cam 4 and bearing 9 described above are positioned such that the central axis O of the cam 4 in a plan view is on the same line as the trajectory of the center of the bearing 9 that moves in the front-to-rear direction. However, it is more effective to position them as shown in FIGS. 11A and 11B.

[0052] 11A shows a state in which the rotation angle of the cam 4 is 0° (the door is closed), and Fig. 11B shows a state in which the rotation angle of the cam 4 is 90° (the door is open). When the reference line LS1 is the movement locus of the center of the bearing 9 that moves in the front-to-rear direction, the cam 4 and bearing 9 shown in these figures are in a positional relationship in which the central axis O of the cam 4 in a plan view is offset from this reference line LS1 to the side (lower side in Fig. 11A) where the portion 4b1 with which the bearing 9 comes into contact when the cam 4 on the outer circumferential portion 4b rotates in a direction from the open position to the closed position (rotates counterclockwise).

[0053] Here, as shown in FIG. 11A, when the rotation angle of the cam 4 is 0°, the contact point where the bearing 9 comes into contact with the outer periphery 4b is defined as point Pa, and the straight line passing through the central axis O and point Pa is defined as the first reference line LS2 before movement. When the cam 4 rotates 90° counterclockwise, the first reference line LS2 before movement moves to the position of point Pa shown in FIG. 11B. The line obtained by rotating the first reference line LS2 before movement by 90° counterclockwise is defined as the first reference line LS3 after movement. Also, as shown in FIG. 11B, when the rotation angle of the cam 4 is 90°, the contact point where the bearing 9 comes into contact with the outer periphery 4b is defined as contact point Pb, and the straight line passing through the central axis O and contact point Pb is defined as the second reference line LS4.

[0054] When the central axis O of the cam 4 is offset as described above, as is clear from FIG. 11B , even if the cam 4 is rotated 90° (the angle between the first reference line LS2 before movement and the first reference line LS3 after movement is 90°), the angle between the first reference line LS3 after movement that passes through point Pa and the second reference line LS4 that passes through point Pb is smaller than 90°. In other words, the amount of change Δr in radius per predetermined angle θ described above is substantially reduced by offsetting the central axis O of the cam 4 as described above. To explain this point using a specific example, in the case of the embodiment shown in FIG. 11B , the angle of the range in which the bearing 9 contacts the cam 4 (the angle between the first reference line LS3 after movement and the second reference line LS4) is approximately 78°. For example, if the outer peripheral portion 4b of the cam 4 has a shape such that the change in radius Δr per 10° is 0.5 mm, the change in radius from point Pa to point Pb is 0.5 mm / 10°*78°=3.9 mm. Because the cam 4 rotates 90° during this time, the change in radius per 10° from point Pa to point Pb is approximately 0.43 mm (3.9 mm / 90°=0.433 mm). In other words, when the central axis O of the cam 4 is offset as described above, the change in radius Δr per predetermined angle θ is substantially reduced. On the other hand, when the central axis O of the cam 4 is not offset from the reference line LS1, the angle at which the cam 4 rotates and the angle over which the bearing 9 contacts the cam 4 as the cam 4 rotates remain unchanged, and therefore the change in radius Δr per predetermined angle θ remains unchanged.

[0055] 6 to 9, the smaller the amount of change Δr in radius per predetermined angle θ, the more it is possible to suppress changes in torque in the cam 4. Therefore, when the central axis O of the cam 4 is offset as described above, the amount of change Δr in radius per predetermined angle θ becomes substantially smaller, and the effect of suppressing changes in torque in the cam 4 can be more advantageously obtained.

[0056] Doors are typically provided with a latch to keep the door in a closed position. The latch is biased from the inside to the outside on the side of the door. When the door closes an opening in a building, the biased latch must come into contact with the opening and move inward, which requires an increase in force applied to the door just before it closes. When considering such a latch, it is preferable to use a cam 4A as shown in Figures 12A and 12B. Figure 12A shows the cam 4A when its rotation angle is 130° (the door is fully open), and Figure 12B shows the cam 4A when its rotation angle is 0° (the door is closed).

[0057] 12A and 12B, cam 4A has a small-diameter portion 4c, where the radius from central axis O to outer periphery 4b is smaller, near the location on outer periphery 4b that contacts bearing 9 when the door is in the closed position. That is, when cam 4A rotates counterclockwise from the state shown in FIG. 12A and small-diameter portion 4c moves to where bearing 9 is located, bearing 9 moves significantly forward toward small-diameter portion 4c. At this time, the elastic energy stored in spring member 13 is released, increasing the force required to move the door, allowing the door to close stably even when a latch is provided on the door.

[0058] 11A and 11B, the central axis O of the cam 4A in a plan view is offset to the side (the lower side in FIG. 12A) where the portion of the outer circumferential portion 4b that comes into contact with the bearing 9 is located when the cam 4A rotates in a direction from the open position to the closed position (counterclockwise), similar to the cam 4 shown in FIGS. 11A and 11B. This means that the amount of change Δr in radius per predetermined angle θ of the cam 4A is substantially small, and therefore the effect of suppressing torque changes in the cam 4A can be more effectively obtained.

[0059] FIG. 13 is a graph showing an example of verification results for an actual door closer 100 using the cam 4A shown in FIGS. 12A and 12B. This graph shows the results of measuring torque each time the angle of cam 4A is changed, starting from when the rotation angle of cam 4A is 0°, and then measuring torque after the rotation angle of cam 4A reaches 90° until the rotation angle of cam 4A reaches 0°. As is clear from the graph, when a closed door begins to open, the torque of cam 4A increases temporarily due to the influence of small diameter portion 4c, but after the rotation angle of the cam exceeds 35°, the torque of cam 4A becomes approximately constant. When closing an open door, if the rotation angle of cam 4A becomes smaller than 30°, the torque of cam 4A increases significantly due to small diameter portion 4c, allowing the door to close even if a latch is provided on the door.

[0060] Although one embodiment of the present invention has been described above with reference to the drawings, the above-described embodiment may be modified as follows: For example, in this embodiment, the bearing 9 is provided at the tip of the slider shaft 8, and this bearing 9 is pressed against the outer periphery 4b of the cam 4, but the tip of the slider shaft 8 may be pressed against the cam 4 without using the bearing 9.

[0061] (Addendum) In one aspect, the present specification discloses the following technology.

[0062] (Technology 1) A door closer that biases a rotating door in a closing direction, a rotation shaft that is rotatable about a vertical central axis in response to rotation of the door, and that rotates from an open position where the door is open to a closed position where the door is closed; a cam that rotates together with the rotary shaft; a slider that is horizontally movable and whose tip contacts the outer periphery of the cam; a spring member that applies elastic force to the slider to press the tip end portion against the outer circumferential portion, A door closer in which the amount of change in radius of the outer periphery is constant for each specified range of rotation angle, with respect to the rotation angle when the cam rotates around the central axis and the radius from the central axis to the outer periphery.

[0063] This technology minimizes the variation in the force required to open the door, resulting in superior door operability. Furthermore, because the structure is simpler and there are fewer factors that cause variation compared to conventional door closers, the door can be operated as intended even when various variations are taken into account.

[0064] (Technology 2) The door closer described in Technology 1, wherein the rotation angle and the torque of the cam around the central axis at the contact point where the tip portion contacts the outer periphery satisfy a relationship in which the gradient of a linear approximation curve obtained by the least squares method is between -0.5 and 2.

[0065] This technology effectively suppresses changes in cam torque and also suppresses the decrease in cam torque that biases the door in the closing direction, thereby ensuring stable performance as a door closer.

[0066] (Technology 3) The door closer described in Technology 1, wherein, in a horizontal plane, when the movement trajectory of the tip when the slider moves horizontally is taken as a reference line, the central axis is offset from the reference line to the side where the part that the tip contacts when the cam on the outer periphery rotates in a direction from the open position toward the closed position is located.

[0067] This technique effectively reduces the amount of change in radius over a given range of rotational angles, advantageously reducing cam torque variations.

[0068] (Technology 4) The door closer according to technology 1, wherein the outer periphery has a small diameter portion where the radius is smaller in the vicinity of the portion where the tip portion comes into contact in the closed position.

[0069] This technology allows the door to close securely even when a latch is installed on the door.

[0070] Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment. Unless otherwise specified in the above description, various modifications and variations are possible within the spirit and scope of the present invention as defined in the claims. For example, the configurations of the above-described embodiment may be added or deleted as appropriate, and the configurations of one embodiment may be incorporated into other embodiments. Furthermore, the effects of the above-described embodiment are merely examples of the effects that can be obtained from the present invention. In other words, the effects of the present invention are not limited to the above-described effects, and additional effects may be obtained in addition to the above-described effects. [Explanation of symbols]

[0071] 3: Rotation axis 4, 4A: Cam 4b: Outer periphery 4c: Small diameter section 7: Slider 9: Bearing (tip) 13: Spring material 100: Door closer O: Central axis

Claims

1. A door closer that biases a rotating door in a closing direction, a rotation shaft that is rotatable about a vertical central axis in response to rotation of the door, and that rotates from an open position where the door is open to a closed position where the door is closed; a cam that rotates together with the rotary shaft; a slider that is horizontally movable and whose tip contacts the outer periphery of the cam; a spring member that applies elastic force to the slider to press the tip end portion against the outer circumferential portion, A door closer in which the amount of change in radius of the outer periphery is constant for each specified range of rotation angle, with respect to the rotation angle when the cam rotates around the central axis and the radius from the central axis to the outer periphery.

2. The door closer according to claim 1, wherein the rotation angle and the torque of the cam around the central axis at the contact point where the tip portion contacts the outer periphery satisfy a relationship in which the slope of a linear approximation curve calculated by the least squares method is between -0.5 and 2.

3. 2. The door closer according to claim 1, wherein, in a horizontal plane, when the movement trajectory of the tip when the slider moves horizontally is taken as a reference line, the central axis is offset from the reference line to the side where the part with which the tip contacts when the cam on the outer periphery rotates from the open position toward the closed position is located.

4. 2. The door closer according to claim 1, wherein the outer circumferential portion has a small diameter portion where the radius is reduced near a portion with which the tip portion comes into contact in the closed position.

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