Door closer

Abstract

Ensure that the closing speed of the door is significantly reduced during delayed action. [Solution] The outer circumferential surface of the head portion 21 is made of the outer circumferential surface of a packing and has a close-contact sliding surface 36 that slides against the inner wall surface 8a of the cylinder portion without a fitting gap, and a fitting sliding surface 33 that is adjacent to at least one of the high-pressure chamber 11 side and the low-pressure chamber 12 side relative to the close-contact sliding surface 36 and slides against the inner wall surface 8a of the cylinder portion with a fitting gap. At least the portion of the outer circumferential surface of the head portion 21 adjacent to the low-pressure chamber 12 side relative to the close-contact sliding surface 36 that faces the main outlet opening 52 is provided where the fitting sliding surface 33 is not provided and a retracted portion 35 is provided that is spaced radially inward from the inner wall surface 8a of the cylinder portion. When the door closes, the close-contact sliding surface 36 closes the main outlet opening 52 and then starts to open the main outlet opening 52, thereby switching from delayed action to main operation.

Description

Technical Field

[0001] The present invention relates to a door closer that performs a delayed action.

Background Art

[0002] In a door closer, the outer peripheral surface of a piston fits onto the inner wall surface of a cylinder filled with hydraulic oil, and thus the oil chamber in the cylinder is partitioned into two chambers, a high-pressure chamber and a low-pressure chamber. Further, the door closer is provided with a flow path for allowing the hydraulic oil to flow between the two chambers. The flow path has an inflow opening that opens into the high-pressure chamber and an outflow opening that opens into the low-pressure chamber. When the piston moves within the cylinder in the door-closing direction, the hydraulic oil flows from the high-pressure chamber to the low-pressure chamber through the flow path.

[0003] There are a plurality of flow paths, and the flow path through which the hydraulic oil flows is switched according to the position of the piston with respect to the cylinder. That is, the flow path through which the hydraulic oil flows is switched according to the opening angle of the door. By switching this flow path, the operation section when the door closes switches from a delayed-action section that performs a delayed action to a main section that performs a main action. The delayed action is control that causes the door to close slowly from the start of closing to a predetermined opening angle, and is for ensuring passage of pedestrians and the like. In the delayed-action section, the hydraulic oil moves from the high-pressure chamber to the low-pressure chamber via the delayed-action flow path. The cross-sectional area of the delayed-action flow path is set small in order to slow down the door-closing speed. On the other hand, in the main section, the hydraulic oil flows through the main flow path. The cross-sectional area of the main flow path is set larger than the cross-sectional area of the delayed-action flow path. Therefore, in the main section, the door closes at a faster speed than in the delayed-action section. Immediately before switching from the delayed-action section to the main section, the outer peripheral surface of the piston faces the outflow opening of the main flow path and closes the outflow opening of the main flow path.

[0004] A small fitting gap exists between the inner wall of the cylinder and the outer surface of the piston. Therefore, a small amount of hydraulic fluid leaks from the high-pressure chamber to the low-pressure chamber through this fitting gap. Furthermore, just before switching from the delayed-action section to the main section, a small fitting gap also exists between the outlet opening of the main flow path and the outer surface of the piston. Therefore, the outlet opening of the main flow path is not completely closed without any gaps, and hydraulic fluid leaks from the main flow path to the low-pressure chamber through this small fitting gap. These leaks of hydraulic fluid contribute to an increase in the door closing speed. In the delayed-action section, it is necessary to set a slower door closing speed, but the hydraulic fluid leakage due to the fitting gaps described above can make it difficult to slow down the door closing speed.

[0005] Patent Document 1, described below, describes a configuration in which a synthetic resin seal portion is provided on the outer circumferential surface of the piston, and a tongue-shaped portion is formed on the seal portion, so that when the hydraulic pressure in the high-pressure chamber rises, the tongue-shaped portion is pressed against the inner wall surface of the cylinder. It also describes providing a metal reinforcing ring on the seal portion. However, since a fitting gap is provided between the outer circumferential surface of the reinforcing ring and the inner wall surface of the cylinder, the hydraulic fluid leakage phenomenon described above occurs. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Utility Model Publication No. 54-47853 [Overview of the project] [Problems that the invention aims to solve]

[0007] The present invention aims to reliably slow down the closing speed in delayed action. [Means for solving the problem]

[0008] The door closer according to the present invention is a door closer that, when a rotating door is closed, performs a delayed action and a main action that follows the delayed action and has a faster closing speed than the delayed action, comprising a housing that defines an oil chamber including a cylinder, and a piston having a head that reciprocates the cylinder in conjunction with the door and divides the oil chamber into a high-pressure chamber that becomes the high-pressure side during the closing operation and a low-pressure chamber that becomes the low-pressure side during the closing operation, wherein the housing is formed with a delayed action passage that connects the high-pressure chamber and the low-pressure chamber for the delayed action and a main passage that connects the high-pressure chamber and the low-pressure chamber for the main action, the main passage has a main outflow opening that opens to the inner wall surface of the cylinder, and the outer surface of the head An annular packing is fitted to the head portion, and the outer circumferential surface of the head portion is made up of the outer circumferential surface of the packing and has a close-contact sliding surface that slides against the inner wall surface of the cylinder portion without a fitting gap, and a fitting sliding surface that is adjacent to at least one of the high-pressure chamber side and the low-pressure chamber side of the close-contact sliding surface and slides against the inner wall surface of the cylinder portion with a fitting gap. On the outer circumferential surface of the head portion, at least the portion facing the main outlet opening of the portion adjacent to the low-pressure chamber side of the close-contact sliding surface is provided with a retracted portion that is spaced radially inward from the inner wall surface of the cylinder portion and does not have a fitting sliding surface. When the door closes, the close-contact sliding surface closes the main outlet opening before starting to open the main outlet opening, thereby switching from delayed action to main operation.

[0009] In this configuration, as the door begins to close, the piston head moves towards the high-pressure chamber, and the hydraulic fluid in the high-pressure chamber flows to the low-pressure chamber through the delayed-action passage. That is, delayed action is performed, and the door closes slowly. The outer surface of the piston head is provided with a close-contact sliding surface that slides against the inner wall surface of the cylinder without any fitting gap. In the delayed-action section, the close-contact sliding surface gradually moves towards the closing side of the inner wall surface of the cylinder, and eventually reaches a position that closes the main outlet opening. A retractable section is provided adjacent to the opening side of the close-contact sliding surface, which is on the low-pressure chamber side, and the retractable section is positioned to correspond to the main outlet opening. Therefore, as the piston moves further towards the closing side from the state where the close-contact sliding surface has closed the main outlet opening, the retractable section begins to face the main outlet opening, and the main outlet opening begins to open. When the main outlet opening begins to open in this way, the hydraulic fluid in the high-pressure chamber begins to flow into the low-pressure chamber through the main passage. In other words, the delayed action phase ends and the main phase begins, the closing action switches from delayed action to main action, and the door closes at a rapid speed.

[0010] As described above, since a close-contact sliding surface is provided on the outer circumferential surface of the piston head, the hydraulic fluid in the high-pressure chamber cannot substantially pass between the outer circumferential surface of the piston head and the inner wall surface of the cylinder. Therefore, in the delayed action section, substantially all of the hydraulic fluid in the high-pressure chamber passes through the delayed action flow path and moves to the low-pressure chamber, resulting in the desired delayed action and allowing the door to be closed at a very slow speed. Moreover, the main outlet opening can be reliably closed by the close-contact sliding surface before switching from the delayed action section to the main section.

[0011] Furthermore, a fitting sliding surface is provided next to the close-contact sliding surface. The fitting sliding surface is provided on at least one of the sides of the close-contact sliding surface, both the closing side and the opening side. By providing a fitting sliding surface next to the close-contact sliding surface in this way, it is possible to prevent the close-contact sliding surface from sliding only against the inner wall surface of the cylinder, thereby reducing the load on the close-contact sliding surface. In other words, the fitting sliding surface located next to the close-contact sliding surface supports the close-contact sliding surface. As a result, the condition of the close-contact sliding surface is more easily maintained even after long-term use, and the close contact between the close-contact sliding surface and the inner wall surface of the cylinder is maintained over a long period of time. Consequently, it becomes possible to perform delayed action at a predetermined slow speed over a long period of time.

[0012] In particular, it is preferable that the fitting sliding surface has a closed-side fitting sliding surface adjacent to the high-pressure chamber side relative to the close-contact sliding surface, and an open-side fitting sliding surface adjacent to the low-pressure chamber side relative to the close-contact sliding surface. With this configuration, fitting sliding surfaces are provided on both sides in the axial direction of the piston relative to the close-contact sliding surface. Therefore, the close-contact sliding surface can be firmly supported from both sides by the two adjacent fitting sliding surfaces, and deterioration such as wear of the close-contact sliding surface can be effectively suppressed.

[0013] Furthermore, it is preferable that the retractable portion is a notch formed at one location on the entire circumference of the outer surface of the head portion. With this configuration, the retractable portion can be easily manufactured. In addition, since the retractable portion is provided on only a part of the entire circumference, the area other than the retractable portion can be used as a fitting sliding surface, and the fitting sliding surface can support the close-contact sliding surface.

[0014] Furthermore, it is preferable that the piston is equipped with a pinion gear that rotates in conjunction with the door, and that the piston has a rack that meshes with the pinion gear, with the rack provided at one location on the entire circumference of the piston, and that the main outlet opening and retraction section be provided within a range of half the circumference of the piston opposite to the angular position where the rack is formed. On the entire circumference of the close-contact sliding surface, the location where a retraction section is provided next to it is a location where the support from the fitting sliding surface is relatively weak because there is no fitting sliding surface provided next to it on the opening side. For this reason, the location where a retraction section is provided next to it is the location on the entire circumference of the close-contact sliding surface that is most prone to deterioration. On the other hand, a force acts radially outward from the pinion gear on the piston rack. For this reason, the angular position where the rack is formed on the entire circumference of the close-contact sliding surface is pressed most strongly against the inner wall surface of the cylinder. Therefore, if the main outlet opening and retraction section are located within the range of half the circumference of the piston opposite to the angular position where the rack is formed, the influence on the close-contact sliding surface due to the force acting from the pinion gear to the rack can be minimized, and deterioration such as wear of the close-contact sliding surface can be suppressed. [Effects of the Invention]

[0015] As described above, by providing a fitting sliding surface, a close-contact sliding surface, and a retractable portion on the outer circumferential surface of the piston head, and by performing the switch from delayed action to main action via the close-contact sliding surface, the closing speed during delayed action can be reliably reduced. [Brief explanation of the drawing]

[0016] [Figure 1] A cross-sectional view of the door closer body in one embodiment of the present invention, with the door opening angle at 0 degrees (fully closed), as seen from the planar side. [Figure 2] Left side view of the same unit. [Figure 3] Cross-sectional view AA in Figure 1. [Figure 4] Cross-sectional view of BB in Figure 1. [Figure 5]The piston before packing is mounted on the same body is shown. (a) is a view seen from the closed side in the axial direction, (b) is a front view of the main part, and (c) is a sectional view taken along the H-G line of (a). [Figure 6] The same piston is shown. (a) is an external view of the main part after the packing is mounted, (b) is a sectional view corresponding to G-G of FIG. 5(a) showing the main part after the packing is mounted, and (c) is a sectional view corresponding to G-G of FIG. 5(a) showing the main part in a state of being mounted on the housing. [Figure 7] A sectional view corresponding to H-G of FIG. 5(a) showing the main part of the same piston after the packing is mounted. [Figure 8] A sectional view of the main part showing the state when the door in the same body starts to close. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 9] A sectional view of the main part showing the state immediately before the bypass flow path in the same body opens. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 10] A sectional view of the main part showing the state when the bypass flow path in the same body is open. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 11] A sectional view of the main part showing the state when the bypass flow path in the same body closes. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 12] A sectional view of the main part showing the state when the main outflow opening in the same body is closed. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 13] A sectional view of the main part showing the state when the closing state of the main outflow opening in the same body ends. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 14] A sectional view of the main part showing the state when the main flow path in the same body is open. (a) is a sectional view taken along the C-D-E line of FIG. 2, and (b) is a sectional view taken along the D-F line of FIG. 2. [Figure 15]A cross-sectional view of the main part showing the state when the sub-channel in the same body is open, where (a) is the C-D-E cross-sectional view of FIG. 2 and (b) is the D-F cross-sectional view of FIG. 2. [Figure 16] A cross-sectional view of the main part showing the state when the door in the same body is closed, where (a) is the C-D-E cross-sectional view of FIG. 2 and (b) is the D-F cross-sectional view of FIG. 2. [Figure 17] A conceptual diagram showing each operation section when the door used by the same door closer closes. [Figure 18] A schematic diagram showing the relationship between the flow path communication section of the same door closer and the door closing speed. [Figure 19] (a) to (c) are cross-sectional views of the main part of the body of the door closer in other embodiments of the present invention, corresponding to FIG. 8(a).

Mode for Carrying Out the Invention

[0017] [[ID=ID=20]]Hereinafter, a door closer according to an embodiment of the present invention will be described with reference to FIGS. The door closer is used for a rotating door. The door is rotatably attached to the door frame via a hinge. The door rotates horizontally about an axis in the vertical direction. The axial direction of the rotation axis of the door is the vertical direction, and the normal direction with respect to the surface of the door is the front-rear direction. Also, the left-right direction is a direction orthogonal to the rotation axis of the door and is a direction connecting the door bottom side close to the rotation axis and the door tip side far from the rotation axis.

[0018] The door closer includes a main body 1 shown in FIGS. 1 to 4, a link mechanism and brackets not shown. The main body 1 is attached to the door or the door frame. In this embodiment, the case where it is attached to the door will be described. The main body 1 is attached at an upper part of the front surface of the door, near the hinge, via a mounting plate not shown. In FIG. 1, the upper side of the paper surface is the door side and the back side, and the lower side of the paper surface is the front side opposite to the door. A bracket is attached to the upper frame of the door frame. The link mechanism connects the main body 1 and the door frame via the bracket.

[0019] <Main body 1> The main body 1 is a rectangular parallelepiped shape that is elongated in the left-right direction. The main body 1 comprises a housing 2 that forms an oil chamber, a main shaft 3 that rotates around an axis in the vertical direction as the door rotates, a pinion gear 4 provided on the main shaft 3 and rotating integrally with the main shaft 3, a piston 6 that reciprocates in the left-right direction within the oil chamber of the housing 2 and engages with the pinion gear 4, and a spring that applies a closing force to the main shaft 3. The housing 2 is attached to the door via the aforementioned mounting plate. The housing 2 is elongated in the left-right direction and has openings at both its left and right ends. The openings at both ends are closed by end caps 7. A cover 13 is attached to the front of the housing 2.

[0020] The internal space of the housing 2 is an oil chamber, which is filled with hydraulic fluid. The oil chamber is long in the left-right direction, and most of it has a circular cross-section. The housing 2 has a cylinder portion 8 which has a circular cross-section and an axis in the left-right direction. The inner wall surface 8a of the cylinder portion 8 is the inner circumferential surface of the housing 2 and has a circular cross-section.

[0021] The spindle 3 has an axis running vertically. The spindle 3 is rotatably supported in the housing 2. The upper end of the spindle 3 protrudes upward from the upper surface of the housing 2, and a link mechanism is connected to this upper end. The pinion gear 4 may be integrally formed with the spindle 3 or may be a separate component. As shown in Figure 1, the spindle 3 is positioned offset to the rear of the housing 2.

[0022] In Figure 1, the piston 6 moves to the right when the door opens and to the left when the door closes. Therefore, the left side is the closed side and the right side is the open side. Note that Figure 1 shows the door in the fully closed state. The piston 6 is made of metal. The piston 6 has a cylindrical first head portion 21 (head portion) located to the left of the main shaft 3, a cylindrical second head portion 22 located to the right of the main shaft 3, and an arm portion 23 that connects the first head portion 21 and the second head portion 22 from left to right. The first head portion 21 and the second head portion 22 slide against the inner wall surface 8a of the cylinder portion 8 and move in the left-right direction.

[0023] The first head section 21 and the second head section 22 each have through holes that penetrate in the axial direction (left-right direction), and a valve 24 is positioned in these through holes. The valve 24 opens the through holes to allow the passage of hydraulic fluid when the door is opened, and closes the through holes to prevent the passage of hydraulic fluid when the door is closed. A filter 25 for removing foreign matter is also positioned in the through hole of the first head section 21.

[0024] The first head portion 21 is located at the left end, which is the closed end of the piston 6. The first head portion 21 divides the oil chamber into two chambers, left and right. That is, the first head portion 21 divides the oil chamber into a high-pressure chamber 11 and a low-pressure chamber 12. In Figure 1, the chamber on the left is the high-pressure chamber 11, which is the chamber that becomes relatively high-pressure when the door is closed. In Figure 1, the chamber on the right is the low-pressure chamber 12, which is the chamber that becomes relatively low-pressure when the door is closed. The second head portion 22 is located at the right end, which is the open end of the piston 6. The second head portion 22 receives spring force from the spring. The second head portion 22 functions as a spring receiving portion.

[0025] The arm portion 23 extends along the left-right direction. The arm portion 23 is provided at only one location around the entire circumference of the piston 6, specifically, only one on the front side. A rack 5 is formed on the arm portion 23. The arm portion 23 is located in front of (towards the front of) the main shaft 3, and the rack 5 is formed on the side of the arm portion 23 facing the main shaft 3, i.e., the back side. The rack 5 protrudes toward the rear. The front surface of the rack 5 is a curved surface and faces the inner wall surface 8a of the cylinder portion 8 with a gap between them, without sliding against it.

[0026] Details of the first head portion 21 will now be described. Figures 5 to 7 show the vicinity of the first head portion 21 of the piston 6. An annular groove 26 is formed on the outer circumferential surface of the first head portion 21. The formation of the annular groove 26 on the outer circumferential surface of the first head portion 21 divides the outer circumferential surface of the first head portion 21 into two axial sections with the annular groove 26 in between. The tip side of the first head portion 21 is the closed side, and the base side is the open side. On the outer circumferential surface of the first head portion 21, a chamfered portion 32, a closed side fitting sliding surface 33a, an annular groove 26, and an open side fitting sliding surface 33b are formed in order from the tip side to the base side. The chamfered portion 32 is provided at the tip of the outer circumferential surface of the first head portion 21. The closed side fitting sliding surface 33a and the open side fitting sliding surface 33b are adjacent to each other on both sides in the axial direction of the annular groove 26. The closing side fitting sliding surface 33a is adjacent to the closing side of the annular groove 26, and the opening side fitting sliding surface 33b is adjacent to the opening side of the annular groove 26. The fitting sliding surface 33 of this embodiment is composed of the closing side fitting sliding surface 33a and the opening side fitting sliding surface 33b, and the fitting sliding surface 33 is divided into two parts in the axial direction by the annular groove 26. The closing side fitting sliding surface 33a and the opening side fitting sliding surface 33b have the same diameter. The fitting sliding surface 33 slides against the inner wall surface 8a of the cylinder portion 8 with a fitting gap. The fitting gap is, for example, several tens of μm in diameter, preferably 50 μm or less. The opening side fitting sliding surface 33b has a larger axial dimension than the closing side fitting sliding surface 33a, i.e., it is wider, but the width of each is arbitrary.

[0027] As shown in Figures 5(a) and (c), a notch 34 is formed on the outer circumferential surface of the first head portion 21. The notch 34 is formed in only one location on the entire circumference of the outer circumferential surface of the first head portion 21. The notch 34 is formed at an angular position on the entire circumference of the outer circumferential surface of the first head portion 21, opposite the main outflow opening 52, which will be described later. The notch 34 is formed along the axial direction and extends along the entire axial length of the outer circumferential surface of the first head portion 21. The annular groove 26 crosses the notch 34 in the circumferential direction. Therefore, the annular groove 26 divides the notch 34 into two parts in the axial direction, and the notch 34 consists of a closed-side notch 34a located on the closed side (tip side) of the annular groove 26 and an open-side notch 34b located on the open side (base side) of the annular groove 26. The notch 34 is a so-called D-cut portion. Therefore, the bottom surface of the notch 34 is flat. In this embodiment, the retractable portion 35 is formed by the opening-side notch 34b. That is, the retractable portion 35 is formed by the opening-side notch 34b formed in a part of the opening-side fitting sliding surface 33b. The depth of the notch 34 is 1 mm or less, preferably several hundred μm, and the annular groove 26 is deeper than the notch 34. The notch is provided on the side of the entire circumference of the piston 6 opposite to the angular position where the rack 5 is formed.

[0028] An annular packing 27 is fitted into the annular groove 26. The packing 27 is made of resin, is elastic, and can be easily elastically deformed in the radial direction. The configuration of the packing 27 may vary, but in this embodiment, the packing 27 has a two-layer structure consisting of an inner packing 27a and an outer packing 27b. Figure 5 shows the state without the packing 27 fitted, and Figures 6 and 7 show the state with the packing 27 fitted. Note that in Figure 6(a), the outer packing 27b is shown with numerous dots, and the same is true in Figure 8 and subsequent figures. Note that in this embodiment, the packing 27 has a two-layer structure, but it may also have a single-layer structure.

[0029] Before being mounted on the piston 6, the outer packing 27b has a rectangular cross-section, and the inner packing 27a has a circular cross-section. The outer packing 27b is superimposed on the radially outward side of the inner packing 27a. The inner packing 27a is mounted on the bottom surface of the annular groove 26. As shown in Figure 6(b), the inner packing 27a becomes slightly elliptical in cross-section when mounted on the annular groove 26 of the piston 6. As shown in Figures 6(a) and (b), the outer circumferential surface of the packing 27 protrudes slightly radially outward from the outer circumferential surface of the first head portion 21 when mounted on the piston 6. Figure 6(c) shows the state when mounted on the housing 2. When the piston 6 is mounted on the housing 2, the outer packing 27b is pushed radially inward by the inner wall surface 8a of the cylinder portion 8. The outer circumferential surface of the outer packing 27b becomes flush with the inner wall surface 8a of the cylinder portion 8, and the inner packing 27a further undergoes elastic deformation in an elliptical shape in cross-section. The inner packing 27a presses the outer packing 27b radially outward due to its elastic restoring force, causing the outer circumferential surface of the outer packing 27b to adhere tightly to the inner wall surface 8a of the cylinder portion 8.

[0030] The close-contact sliding surface 36 is formed by the outer circumferential surface of the packing 27. The close-contact sliding surface 36 is made up of the outer circumferential surface of the outer packing 27. The close-contact sliding surface 36 slides against the inner wall surface 8a of the cylinder portion 8 without any fitting gap. A closing-side fitting sliding surface 33a and an opening-side fitting sliding surface 33b are provided adjacent to each other on both sides of the close-contact sliding surface 36 in the axial direction. Therefore, the close-contact sliding surface 36 is sandwiched in the axial direction by the closing-side fitting sliding surface 33a and the opening-side fitting sliding surface 33b. The close-contact sliding surface 36 is a resin sliding surface, and the fitting sliding surface 33 is a metal sliding surface.

[0031] When the pinion gear 4 and the rack 5 mesh, the rack 5 receives a force from the pinion gear 4. This force is divided into a left-right component and a front-rear component. The direction of the front-rear component is in the direction that moves the rack 5 away from the pinion gear 4. In this embodiment, the rack 5 is located on the front side of the pinion gear 4. Therefore, the direction of the front-rear component force that the rack 5 receives from the pinion gear 4 is perpendicular to the main shaft 3 and is on the front side. In Figures 4 and 5(a), the direction of the front-rear component force that the rack 5 receives from the pinion gear 4 is indicated by arrow 200. The retraction portion 35, which consists of the opening side notch portion 34b, is provided at an angular position on the entire circumference of the piston 6 that is different from the direction of the front-rear component force that the rack 5 receives from the pinion gear 4. In detail, the retractable section 35 is provided in an angular range 201 of half a circumference (180 degrees) of the piston 6, on the side opposite to the direction of the forward / backward force component that the rack 5 receives from the pinion gear 4.

[0032] The spring is located to the right of the piston 6. The spring may be a single spring, but in this embodiment it consists of two springs: a main spring 29 and a sub-spring 30. The spring is a coil spring. The spring is compressed when the door opens by being pushed by the piston 6. The main spring 29 and the sub-spring 30 are arranged coaxially, with the sub-spring 30 having a smaller diameter than the main spring 29 and being located radially inward of the main spring 29. The spring and the piston 6 are also arranged coaxially. The centerlines of the spring and the piston 6 are on the same line and coincide with the centerline 14 of the cylinder section 8. In a plan view, the main shaft 3 is positioned rearward from the centerline 14 of the cylinder section 8.

[0033] Housing 2 has a passage formed therein for supplying hydraulic fluid from the high-pressure chamber 11 to the low-pressure chamber 12 when the door closes. The passage is configured to control the door closing speed by controlling the flow resistance of the hydraulic fluid flowing through it. Multiple passages are provided, and the closing speed is controlled by dividing the entire angular range from the fully open state to the fully closed state into multiple angular ranges (sections). This will be explained in detail below.

[0034] Figure 17 conceptually illustrates the range of movement when a door closes from a fully open state to a fully closed state. For example, the fully open state is described as having an opening angle of 140 degrees. The closing operation can be broadly divided into three sections. That is, the entire angular range is divided sequentially toward the closing side into a delayed action section 100 in which a delayed action is performed within a predetermined angular range from the fully open state (140 degrees), a main section 101 which follows and performs the main operation, which is the primary closing operation, and a sub-section 102 which follows and performs the closing operation up to the fully closed state (0 degrees). Hereafter, the delayed action will be simply referred to as DA, and the delayed action section 100 will be referred to as the DA section 100. In this embodiment, there is no latching section for latching, but if a latching section is provided, it will be provided after the sub-section 102. In that case, the entire angular range will be divided into four sections.

[0035] The closing speed in DA section 100 is defined as the DA speed, the closing speed in main section 101 is defined as the main speed, and the closing speed in sub section 102 is defined as the sub speed. DA is the action of slowly closing the door, and the DA speed is the slowest. DA section 100 is set to span 90 degrees. That is, DA section 100 is set to open angles smaller than 90 degrees. DA is released when the opening angle is between 60 and 75 degrees. Therefore, DA section 100 is set to open angles of approximately 70 degrees, for example. The time required for the door to close from 90 degrees to the angle at which DA is released can be set to 10 seconds or more by the speed control valve 31, which will be described later.

[0036] The main speed is faster than the DA speed and faster than the sub-speed. Main section 101 starts with an opening angle smaller than 90 degrees. Sub-section 102 is the section where the closing motion is slow at the end of closing. The sub-speed is slower than the main speed and faster than the DA speed. Main section 101 is longer than sub-section 102.

[0037] Furthermore, in this embodiment, a rapid speed change section 103 is provided in the middle of the DA section 100. However, the rapid speed change section 103 may be omitted. The rapid speed change section 103 is a part of the DA section in which a rapid speed change operation is performed. A rapid speed change operation is an operation in which the door closing speed increases from the DA speed and then decreases back to the DA speed. In the rapid speed change section 103, the door closing speed increases rapidly and then decreases rapidly. That is, when the rapid speed change section 103 begins, the door closing speed increases rapidly from the DA speed, and when the rapid speed change section 103 ends, the door closing speed decreases rapidly back to the DA speed. In the rapid speed change operation, the door closing speed increases to a speed faster than the main speed. After that, the door closing speed immediately decreases back to the DA speed.

[0038] The abrupt speed change operation takes place in the middle of the DA section. Therefore, the abrupt speed change section 103 is set to be on the closing side of the starting point of the DA section 100 and on the opening side of the ending point of the DA section 100. Since the abrupt speed change section 103 is set in the middle of the DA section 100, it is shorter than the DA section 100 and also shorter than the main section 101. The abrupt speed change section 103 is set near the 90-degree opening angle, preferably straddling the 90-degree opening angle. That is, it is preferable that the starting point of the abrupt speed change section 103 is on the opening side of 90 degrees, and the ending point of the abrupt speed change section 103 is on the closing side of 90 degrees.

[0039] The aforementioned flow paths are provided for controlling the closing speed in each of these sections. Accordingly, the housing 2 is provided with a DA flow path 40 for DA, a main flow path 50 for the main operation which is the primary door closing operation, and a sub-flow path 60 for the closing operation. Furthermore, separate from these flow paths, a bypass flow path 70 is provided for abrupt speed changes. Note that if abrupt speed changes are not performed as described above, the bypass flow path 70 is omitted.

[0040] Each flow path has two openings that communicate with the oil chamber. The two openings are located in the wall of the oil chamber and consist of an inlet opening, which is the entrance for oil to flow from the oil chamber into the flow path, and an outlet opening, which is the outlet for oil to flow from the flow path into the oil chamber. When the door opens, the direction in which the piston 6 moves is called the opening side, and when the door closes, the direction in which the piston 6 moves is called the closing side. In Figure 1, the opening side is on the right and the closing side is on the left. The inlet opening is on the closing side, and the outlet opening is on the opening side.

[0041] The DA flow path 40 has two openings communicating with the oil chamber: a DA inlet opening 41 and a DA outlet opening 42. The DA inlet opening 41 opens into the inner wall surface 8a of the cylinder portion 8, which is the part of the inner circumferential surface of the housing 2 where the piston 6 slides. On the other hand, the DA outlet opening 42 opens into the part of the inner circumferential surface of the housing 2 where the piston 6 does not slide. Therefore, the DA outlet opening 42 is not closed by the piston 6 and is always open regardless of the opening and closing operation of the door.

[0042] As shown in Figure 8(a), the DA flow path 40 extends radially outward from the DA inlet opening 41, which is the closed opening, towards the housing 2, then changes direction and extends a predetermined length in the left-right direction toward the open side, and then changes direction again downward and extends further. The portion of the total length of the DA flow path 40 that extends in the left-right direction is called the DA horizontal section 43, and the portion that extends in the up-down direction is called the DA vertical section 44. From the DA vertical section 44, the DA flow path 40 further extends toward the oil chamber as shown by the dashed line in Figure 8, and communicates with the oil chamber at the DA outlet opening 42, which is the open opening. As shown in Figure 3, a speed control valve 31 is provided in the DA flow path 40. The DA flow path 40 is a variable-speed flow path in which the speed control valve 31 is located. The speed control valve 31 is provided in the DA vertical section 44 of the DA flow path 40.

[0043] The main flow path 50 has two openings communicating with the oil chamber: a main inlet opening 51 and a main outlet opening 52. Both the main inlet opening 51 and the main outlet opening 52 open into the inner wall surface 8a of the cylinder portion 8 of the housing 2. As shown in Figures 1 and 8(a), the main flow path 50 extends radially outward from the main inlet opening 51 of the housing 2, then changes direction and extends a predetermined length in the left-right direction toward the opening side, and then changes direction further radially inward from the housing 2 and extends to communicate with the oil chamber at the main outlet opening 52. The portion of the main flow path 50 that extends in the left-right direction is called the main horizontal section 53. A speed control valve 31 is provided in the main flow path 50. The main flow path 50 is a variable-speed flow path in which the speed control valve 31 is located. The speed control valve 31 is located in the main horizontal section 53 of the main flow path 50. The main flow path 50 is located below the DA horizontal section 43 of the DA flow path 40. Furthermore, as shown in Figure 8(a), the main inlet opening 51 is located on the closed side of the DA inlet opening 41, and the main outlet opening 52 is located on the open side of the DA inlet opening 41.

[0044] The sub-flow channel 60 has two openings communicating with the oil chamber: a sub-inlet opening 61 and a sub-outlet opening 62. Both the sub-inlet opening 61 and the sub-outlet opening 62 open into the inner wall surface 8a of the cylinder section 8. As shown in Figure 8(a), the sub-flow channel 60 extends radially outward from the sub-inlet opening 61 to the housing 2, then changes direction and extends a predetermined length in the left-right direction toward the opening side, and then changes direction further radially inward from the housing 2 and extends to communicate with the oil chamber at the sub-outlet opening 62. The portion of the sub-flow channel 60 that extends in the left-right direction is called the sub-horizontal section 63. A speed control valve 31 is provided in the sub-flow channel 60. The sub-flow channel 60 is a variable-speed flow channel in which the speed control valve 31 is located. The speed control valve 31 is provided in the sub-horizontal section 63 of the sub-flow channel 60. As shown in Figure 2, the speed control valve 31 for the main flow path 50 and the speed control valve 31 for the sub-flow path 60 are arranged vertically next to each other, and both can be adjusted from the left side of the housing 2.

[0045] Furthermore, the sub-horizontal section 63 of the sub-channel 60 is on the same line as and connected to the DA horizontal section 43 of the DA channel 40. The sub-horizontal section 63 and the DA horizontal section 43 constitute a single continuous opening. The sub-inlet opening 61 is on the closed side of the main inlet opening 51. The sub-outlet opening 62 is common to the DA inlet opening 41. That is, the sub-outlet opening 62 and the DA inlet opening 41 are the same opening.

[0046] The bypass passage 70 has two openings communicating with the oil chamber: a bypass inlet opening 71 and a bypass outlet opening 72. Both the bypass inlet opening 71 and the bypass outlet opening 72 open into the inner wall surface 8a of the cylinder section 8. As shown in Figure 8(b), the bypass passage 70 extends radially outward from the bypass inlet opening 71 to the housing 2, then changes direction and extends a predetermined length in the left-right direction toward the opening side, and then changes direction further radially inward from the housing 2 and extends to communicate with the oil chamber at the bypass outlet opening 72. The portion of the bypass passage 70 that extends in the left-right direction is called the bypass horizontal section 73. The bypass passage 70 is not equipped with a speed control valve 31. Therefore, the bypass passage 70 is a fixed-speed passage without a speed control valve 31.

[0047] Furthermore, the bypass horizontal section 73 of the bypass channel 70, the main horizontal section 53 of the main channel 50, the sub-horizontal section 63 of the sub-channel 60, and the DA horizontal section 43 of the DA channel 40 are arranged to be circumferentially offset from each other with respect to the centerline of the piston 6. The bypass inlet opening 71 and the bypass outlet opening 72 are both located on the opening side of the DA inlet opening 41. The bypass channel 70 preferably connects the high-pressure chamber 11 and the low-pressure chamber 12 when the door opening angle is near 90 degrees, and it is preferable that the bypass channel 70 is set to connect the high-pressure chamber 11 and the low-pressure chamber 12 in an angular range that straddles the 90-degree opening angle. In addition, it is preferable that the angular range in which the bypass channel 70 connects the high-pressure chamber 11 and the low-pressure chamber 12 is set to 10 degrees or less. Therefore, it is preferable that the connecting section of the bypass channel 70 is an angular range of 10 degrees or less that straddles the 90-degree opening angle.

[0048] The cross-sectional areas of each channel have the following relationship. Note that the cross-sectional area of ​​a channel is the cross-sectional area at the narrowest point in the channel. The cross-sectional area of ​​the DA channel 40 is the smallest, the cross-sectional area of ​​the sub-channel 60 is the next largest, the cross-sectional area of ​​the main channel 50 is the next largest, and the cross-sectional area of ​​the bypass channel 70 is the largest. In other words, the relationship is: cross-sectional area of ​​DA channel 40 < cross-sectional area of ​​sub-channel 60 < cross-sectional area of ​​main channel 50 < cross-sectional area of ​​bypass channel 70. Note that speed control valves 31 are provided in the DA channel 40, main channel 50, and sub-channel 60, but in normal use they are set to maintain the above relationship. Furthermore, even if the speed control valve 31 of the DA channel 40 is set to its maximum, the relationship remains: cross-sectional area of ​​DA channel 40 < cross-sectional area of ​​bypass channel 70. Similarly, even if the speed control valve 31 of the main channel 50 is set to its maximum, the relationship remains: cross-sectional area of ​​main channel 50 < cross-sectional area of ​​bypass channel 70.

[0049] Next, the operation of the door when it closes will be explained sequentially from the fully open state to the fully closed state, referring to Figures 8 to 16. Note that in Figures 8 to 16, only the first head portion 21 of the piston 6 is shown in the external view. Also, the arrows in the figures indicate the flow of hydraulic fluid.

[0050] Figure 8 shows the state when the door begins to close from the fully open position. The hydraulic fluid in the high-pressure chamber 11 moves from the DA inlet opening 41 through the DA flow path 40 to the low-pressure chamber 12 through the DA outlet opening 42. Because the cross-sectional area of ​​the DA flow path 40 is small, the door closes slowly at the DA speed. That is, DA is performed over a predetermined angular range from the fully open position.

[0051] Figure 9 shows the state immediately before the abrupt speed change operation begins. In other words, it shows the state just before the bypass channel 70 opens. In this state, the bypass inlet opening 71 is not blocked by the first head portion 21 of the piston 6 and is in an open state. On the other hand, the bypass outlet opening 72 is closed by the first head portion 21, but opens immediately afterward. The abrupt speed change operation is set for the latter half of the DA section 100.

[0052] Figure 10 shows the state when the bypass channel 70 is open. Neither the bypass inlet opening 71 nor the bypass outlet opening 72 are blocked by the first head section 21, and both are open. The hydraulic fluid from the high-pressure chamber 11 moves to the low-pressure chamber 12 through the bypass channel 70. Because the cross-sectional area of ​​the bypass channel 70 is much larger than that of the DA channel 40, even though the DA channel 40 is in communication, due to the difference in flow resistance, the hydraulic fluid effectively flows through the bypass channel 70. As the hydraulic fluid flows through the bypass channel 70, the door closing speed increases sharply from the DA speed and rises rapidly to a speed that exceeds the main speed. However, the time and angular range in which the door closes at a closing speed exceeding the main speed is very short.

[0053] Figure 11 shows the state at the timing when the bypass passage 70 is closed. At this timing, the bypass inlet opening 71 is closed by the first head section 21, and the bypass passage 70 becomes closed. The hydraulic fluid can no longer flow through the bypass passage 70, and the hydraulic fluid in the high-pressure chamber 11 is directed towards the DA passage 40, which has high flow resistance. Up until then, the door had been closing at a high speed because the bypass passage 70 was open, but with the closure of the bypass passage 70, the flow resistance of the hydraulic fluid flowing from the high-pressure chamber 11 to the low-pressure chamber 12 increases dramatically, and the closing speed decreases sharply. As a result, the inertia of the door during the closing operation acts on the piston 6 via the main shaft 3, and the hydraulic fluid in the high-pressure chamber 11 is rapidly pressurized by the piston 6. The pressure in the high-pressure chamber 11 is rapidly increased, and this increased hydraulic fluid pressure acts on the DA passage 40, and in particular acts on the throttling portion of the speed control valve 31 of the DA passage 40. Therefore, clogging of the throttle portion of the speed control valve 31 in the DA flow path 40 with foreign matter such as metal powder can be prevented. Furthermore, even if foreign matter does clog the throttle portion of the speed control valve 31 in the DA flow path 40, the rapidly increased pressure of the hydraulic fluid can push the foreign matter towards the low-pressure chamber 12, thereby clearing the blockage in the DA flow path 40.

[0054] After this abrupt speed change operation, the system returns to DA. Figure 12 shows the state after the abrupt speed change operation and the system has returned to DA. The closing speed is constant, which is the DA speed, until the opening angle reaches approximately 70 degrees. The main outlet opening 52 is closed by the close-contact sliding surface 36 of the first head section 21. There is no fitting gap between the close-contact sliding surface 36 and the inner wall surface 8a of the cylinder section 8. Therefore, the main outlet opening 52 is completely closed by the close-contact sliding surface 36, and the hydraulic fluid in the high-pressure chamber 11 cannot pass between the outer circumferential surface of the first head section 21 and the inner wall surface 8a of the cylinder section 8 to move to the low-pressure chamber 12. Therefore, virtually all of the hydraulic fluid in the high-pressure chamber 11 flows through the DA flow path 40. Consequently, DA can be performed at a predetermined slow closing speed.

[0055] Figure 13 shows the state at the moment when the closing state of the main outlet opening 52 by the close-contact sliding surface 36 ends. Immediately after this, the system transitions from the DA section 100 to the main section 101, and switches from DA to main operation. An opening-side fitting sliding surface 33b is provided adjacent to the opening side of the close-contact sliding surface 36, but the opening-side fitting sliding surface 33b is not provided in the position facing the main outlet opening 52, and a retracted section 35 is provided instead. Therefore, when the door closes further from the state shown in Figure 13 and the first head section 21 moves to the closed side, the closing state of the main outlet opening 52 by the close-contact sliding surface 36 ends, the retracted section 35 begins to face the main outlet opening 52, and the main outlet opening 52 opens.

[0056] Figure 14 shows the state when the main operation is being performed. The close-contact sliding surface 36 is located between the main inlet opening 51 and the main outlet opening 52. Therefore, both the main inlet opening 51 and the main outlet opening 52 are open, and the main flow path 50 is in communication. The DA flow path 40 is in communication, but the hydraulic fluid in the high-pressure chamber 11 effectively flows through the main flow path 50 to the low-pressure chamber 12. Because the cross-sectional area of ​​the main flow path 50 is large, the door closes at a main speed that is faster than the DA speed until it is almost closed. After the state shown in Figure 14, when the first head portion 21 of the piston 6 moves further to the closing side, there is a timing when the first head portion 21 closes the DA inlet opening 41. Even in that state, the sub-inlet opening 61 is open, so the DA flow path 40 is in communication. However, as mentioned above, although the DA flow path 40 is in a connected state, due to the difference in flow resistance, the hydraulic fluid in the high-pressure chamber 11 effectively flows through the main flow path 50 to the low-pressure chamber 12.

[0057] Figure 15 shows the state as the door is about to close, at the time when the main section ends and the sub-section 102 begins. The main inlet opening 51 is closed by the close-contact sliding surface 36, and the main flow path 50 becomes closed. On the other hand, both the sub-inlet opening 61 and the sub-outlet opening 62 are open, and the sub-flow path 60 is in an open state. Although the DA flow path 40 is also in an open state, the hydraulic fluid in the high-pressure chamber 11 effectively flows through the sub-flow path 60 to the low-pressure chamber 12. Since the cross-sectional area of ​​the sub-flow path 60 is smaller than the cross-sectional area of ​​the main flow path 50, the door closes at a sub-speed that is slower than the main speed, and eventually reaches the fully closed state shown in Figure 16. When it is fully closed, the end face of the first head portion 21 of the piston 6 comes into contact with the end cap 7.

[0058] Figure 18 shows a conceptual diagram of the communication sections and closing speeds of each flow path. As described above, in this embodiment, the door begins to close from 140 degrees. In DA mode, the door closes at DA speed S1; in main operation mode, the door closes at main speed S2; and in sub-operation mode, the door closes at sub-speed S3. In rapid speed change operation, the door rises from DA speed S1 to maximum speed S4, then immediately descends back to the original DA speed S1.

[0059] As described above, in the DA section, the close-contact sliding surface 36 moves toward the closing side while sliding against the inner wall surface 8a of the cylinder section 8. Since there is no fitting gap between the close-contact sliding surface 36 and the inner wall surface 8a of the cylinder section 8, the hydraulic fluid in the high-pressure chamber 11 cannot substantially pass between the outer circumferential surface of the first head section 21 of the piston 6 and the inner wall surface 8a of the cylinder section 8. Therefore, substantially all of the hydraulic fluid in the high-pressure chamber 11 passes through the DA passage 40, the DA is executed as set, and the door can be closed at a very slow speed.

[0060] Furthermore, just before switching from DA to main operation, the close-contact sliding surface 36 can reliably close the main outlet opening 52. A retractable section 35 is provided adjacent to the opening side of the close-contact sliding surface 36, and the retractable section 35 is formed at a circumferential position corresponding to the main outlet opening 52. Therefore, when the piston 6 moves to the closing side from the state where the close-contact sliding surface 36 closes the main outlet opening 52, the retractable section 35 faces the main outlet opening 52, and the main outlet opening 52 begins to open. In this way, the switch from DA to main operation can be reliably performed by the close-contact sliding surface 36. In addition, DA can be executed at the set speed until just before switching to main operation.

[0061] Furthermore, a fitting sliding surface 33 is provided next to the close-contact sliding surface 36. In particular, in this embodiment, a closing-side fitting sliding surface 33a and an opening-side fitting sliding surface 33b are provided on both sides of the close-contact sliding surface 36 in the axial direction. Therefore, the close-contact sliding surface 36, which is made of a relatively soft material, can be firmly supported from both sides by the closing-side fitting sliding surface 33a and the opening-side fitting sliding surface 33b, which are made of relatively hard materials, and deterioration such as sagging of the close-contact sliding surface 36 can be effectively suppressed. Consequently, the close contact between the close-contact sliding surface 36 and the inner wall surface 8a of the cylinder portion 8 is maintained for a long period of time, making it possible to perform DA at a predetermined slow speed for a long period of time.

[0062] Furthermore, since the notch 34 constitutes the retraction portion 35, the retraction portion 35 can be easily formed. Also, by making the notch 34 the retraction portion 35, the retraction portion 35 is provided only on a part of the entire circumference, and the part of the entire circumference other than the retraction portion 35 can be the open-side fitting sliding surface 33b. As a result, the open-side fitting sliding surface 33b can firmly support the close-contact sliding surface 36 from the side.

[0063] Furthermore, a retracted section 35 is provided facing the main outlet opening 52, and this retracted section 35 is located in an angular range 201 of half a circumference (180 degrees) of the piston 6's entire circumference, on the opposite side of the direction of the force that the rack 5 receives from the pinion gear 4. As a result, the influence of the force acting from the pinion gear 4 on the rack 5 on the close contact sliding surface 36 can be minimized, and deterioration such as wear of the close contact sliding surface 36 can be suppressed.

[0064] Furthermore, as shown in Figure 19(a), a small-diameter portion 37 may be provided adjacent to the opening side of the close-contact sliding surface 36, and the retractable portion 35 may be formed by this small-diameter portion 37. In this case, the retractable portion 35 will be provided around the entire circumference. Alternatively, as shown in Figure 19(b), the closing-side fitting sliding surface 33a may be provided around the entire circumference without providing the closing-side notch portion 34a. In this case, the chamfered portion 32 will be provided around the entire circumference. Moreover, as shown in Figure 19(c), the closing-side fitting sliding surface 33a may be omitted. [Explanation of symbols]

[0065] 1 Main unit 2 Housing 3 main axis 4 pinion gear 5 racks 6 pistons 7 End caps 8 Cylinder section 8a Inner wall surface 11 High-pressure chamber 12 Low-pressure chamber 13 Cover 14. Centerline of the cylinder section 21. First head section (head section) 22 Second Head Section 23 Arm 24 valves 25 Filters 26 Annular groove 27 Packing 27a Inner packing 27b Outer packing 29 Main spring 30 Sub-springs 31 Speed ​​control valve 32 Chamfered section 33 Fitting sliding surface 33a Closing side fitting sliding surface 33b Opening side fitting sliding surface 34 Notch 34a Closed side notch 34b Opening side notch 35 Evacuation Area 36 Close contact sliding surface 37 Small diameter section 40 DA channel 41 DA Inlet Opening 42 DA Outlet 43 DA horizontal section 44 DA vertical section 50 Main channel 51 Main Inlet Opening 52 Main Outlet 53 Main horizontal section 60 Subchannels 61 Sub-inlet opening 62 Sub-outlet openings 63 Sub-horizontal section 70 Bypass channel 71 Bypass Inlet Opening 72 Bypass Outlet Opening 73 Bypass horizontal section 100 DA section 101 Main section 102 Sub-section 103 Sections with sudden speed changes

Claims

1. A door closer that, when a rotating door closes, performs a delayed action and a main action that follows the delayed action and has a faster closing speed than the delayed action, A housing that defines the oil chamber including the cylinder section, It comprises a piston having a head that reciprocates in conjunction with the door and divides the oil chamber into a high-pressure chamber that becomes high-pressure when the door is closed and a low-pressure chamber that becomes low-pressure when the door is closed, The housing is formed with a delayed action channel that connects the high-pressure chamber and the low-pressure chamber for delayed action, and a main channel that connects the high-pressure chamber and the low-pressure chamber for main operation. The main flow path has a main outflow opening that opens onto the inner wall surface of the cylinder section. An annular packing is fitted to the outer surface of the head. The outer circumferential surface of the head portion consists of the outer circumferential surface of the packing and has a close-contact sliding surface that slides against the inner wall surface of the cylinder portion without a fitting gap, and a fitting sliding surface adjacent to at least one of the high-pressure chamber side and the low-pressure chamber side of the close-contact sliding surface and slides against the inner wall surface of the cylinder portion with a fitting gap. On the outer circumferential surface of the head portion, at least the portion adjacent to the low-pressure chamber side with respect to the close-contact sliding surface, and facing the main outlet opening, a retracted portion is provided that is spaced radially inward from the inner wall surface of the cylinder portion, without a fitting sliding surface. A door closer that switches from delayed action to main action by having the close-contact sliding surface close the main outlet opening before beginning to open the main outlet opening when the door closes.

2. The door closer according to claim 1, wherein the fitting sliding surface has a closing side fitting sliding surface adjacent to the high-pressure chamber side with respect to the close-contact sliding surface, and an opening side fitting sliding surface adjacent to the low-pressure chamber side with respect to the close-contact sliding surface.

3. The retractable portion is a notch formed at one location on the entire circumference of the outer surface of the head portion, as described in claim 1.

4. It is equipped with a pinion gear that rotates in conjunction with the door, and the piston has a rack that meshes with the pinion gear, and the rack is provided at one point around the entire circumference of the piston. The door closer according to claim 3, wherein the main outlet opening and retraction section are provided within a range of half the circumference of the piston opposite to the angular position where the rack is formed.

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