Dust cover

Abstract

This design ensures sufficient fitting force for the dust cover while also allowing for easy removal of the dust cover from the smoke detector. [Solution] The dustproof cover 10 is a cover that can be attached to and removed from the smoke detector 12, and is provided with a cover body that covers the outside of the smoke detector 12, including the smoke inlet 1210, and has an opening at the top, and a fitting structure that has a first fitting part and a second fitting part. The fitting structure has a first fitting part, which is formed on the side of the cover body, protruding inward in an annular shape at a predetermined interval in a plan view, and has a fitting recess 22 at the upper end that fits into the smoke inlet 1210 by entering into the smoke inlet 1210 and restricts movement in the rotational direction, and a second fitting part, which is formed further inward from the fitting recess 22, and has a fitting claw part 24 at the lower end that abuts against the lower end of the smoke inlet 1210 and fits into the smoke inlet 1210 by entering into the smoke inlet 1210 and restricts downward movement.

Description

Technical Field

[0001] The present invention relates to a dust-proof cover to be attached to a smoke detector.

Background Art

[0002] Conventionally, smoke detectors are installed on the ceiling of a building due to construction work or the like. However, dust and dirt are likely to generate at the construction site during construction work, and the dust and dirt enter the inside from the smoke inlet of the smoke detector, causing clogging of the insect-proof net or affecting the detection sensitivity of the smoke detection unit and reducing the detection function. Therefore, by attaching a dust-proof cover to the smoke detector before use, dust and dirt are prevented from entering through the smoke inlet, and when the construction is completed and the use of the smoke detector is started, the dust-proof cover is removed from the smoke detector (Patent Document 1).

[0003] In addition, in order to prevent the dust-proof cover from falling naturally from the smoke detector installed on the ceiling, the dust-proof cover is provided with a fitting structure that fits into the smoke inlet. In Patent Document 1, an engaging protrusion formed by protruding inward from the side surface of the dust-proof cover is provided as the fitting structure. By engaging (fitting) the engaging protrusion with the smoke inlet of the smoke detector, the dust-proof cover is attached to the smoke detector, and by fitting a removal jig into the dust-proof cover and rotating it, the engaging protrusion is disengaged from the smoke inlet and the dust-proof cover can be removed from the smoke detector.

[0004] In addition, the process from the manufacture of the dust-proof cover to the installation of the smoke detector is, for example, as follows. First, the dust-proof covers manufactured by the dust-proof cover manufacturer are packed in a packing box in a stacked state and delivered from the dust-proof cover manufacturer to the smoke detector manufacturer. Then, one dust-proof cover is removed from the stacked dust-proof covers and attached to the smoke detector, the smoke detector with the dust-proof cover attached is packed in a packing box and transported to the construction site, and the smoke detector with the dust-proof cover attached is taken out at the construction site and installed on the ceiling or the like.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Application Publication No. 6-314386 [Overview of the project] [Problems that the invention aims to solve]

[0006] Incidentally, when a dust cover is attached to a smoke detector, it is desirable that the force with which the dust cover fits onto the smoke detector (fitting force) is large to prevent the dust cover from coming off unintentionally. On the other hand, when removing the dust cover from the smoke detector, it is desirable that the fitting force of the dust cover be small in order to make removal easier.

[0007] However, in Patent Document 1, if the amount of inward protrusion of the engaging projection or the width of the rotational direction when removing the dust cover is increased in an attempt to increase the fitting force of the dust cover, the engaging projection becomes difficult to disengage from the smoke inlet, making it difficult to remove the dust cover from the smoke detector and reducing the efficiency of the removal work.

[0008] On the other hand, if the amount of inward protrusion of the engaging projection is reduced or the width is narrowed in an attempt to reduce the fitting force of the dust cover, the engaging projection may come loose from the smoke inlet, potentially causing the dust cover to detach from the smoke detector at an unintended time and allowing dust and dirt to enter the inside of the smoke detector through the smoke inlet.

[0009] Therefore, increasing or decreasing the fitting force of the dust cover would inevitably lead to some kind of problem. It was difficult to simultaneously ensure sufficient fitting force to prevent the dust cover from coming off the smoke detector at an unintended time, and to allow the dust cover to be easily removed from the smoke detector by rotating it.

[0010] The present invention aims to provide a dust cover that can achieve both sufficient fitting force for the dust cover and easy removal of the dust cover from the smoke detector. [Means for solving the problem]

[0011] (Dust cover) The present invention provides a dust cover that can be attached to or removed from a smoke detector, A cover body that covers the outside of the smoke detector, including the smoke inlet, with an opening on the upper side where the smoke detector will be installed, When a dust cover is attached to a smoke detector, the fitting structure includes a first fitting portion that fits into the smoke inlet and restricts the rotational movement of the dust cover about the vertical axis, and a second fitting portion that fits into the smoke inlet and restricts the downward movement of the dust cover. It is characterized by the provision of [a feature].

[0012] (Removable dust cover structure) The fitting structure is designed so that when a rotational force exceeding the rotational force restricted by the first fitting portion is applied to the dustproof cover, the side end of the first fitting portion comes into contact with the side end of the smoke inlet, causing the first fitting portion to deform, thereby releasing the fitting of the first fitting portion and the second fitting portion, and allowing the dustproof cover to be removed from the smoke detector.

[0013] (A fitting structure equipped with a fitting recess and a fitting claw portion) The first fitting portion is a fitting recess formed on the side of the cover body, protruding inward in an annular shape at predetermined intervals when viewed from above, with its upper end fitting into the smoke inlet and restricting rotational movement. The second fitting portion is formed by protruding further inward from a predetermined fitting recess, and its lower end abuts against the lower end of the smoke inlet and enters the smoke inlet, thereby fitting into the smoke inlet and restricting downward movement.

[0014] (Arrangement of the fitting recess and fitting claw portion) The fitting recesses are formed in four locations on the side of the cover body, in a ring shape in plan view, at predetermined intervals. The mating claws are formed in at least two opposing mating recesses out of the four mating recesses formed therein.

[0015] (Beveled recessed area) The upper end of the fitting recess has a predetermined chamfer on both sides in the rotational direction. The fitting structure is designed so that when a rotational force exceeding the rotational force restricted by the fitting recess is applied to the dustproof cover, the chamfered portion of the fitting recess comes into contact with the side edge of the smoke inlet, causing the fitting recess to deform, thereby releasing the engagement of the fitting recess and the fitting claw and allowing the dustproof cover to be removed from the smoke detector.

[0016] (leg) Multiple legs are provided on the cover body at predetermined intervals in a ring shape when viewed from above, so as to protrude below the lower surface of the cover body. The fitting recess is formed between the predetermined legs, By applying a rotational force to the legs that exceeds the rotational force restricted by the fitting recess, the dust cover can be rotated, releasing the engagement of the fitting recess and the fitting claw, and the dust cover can be removed from the smoke detector. [Effects of the Invention]

[0017] (Effect of dust cover) The present invention provides a dustproof cover that can be attached to and removed from a smoke detector, comprising: a cover body that covers the outside of the smoke detector, including the smoke inlet, and has an opening on the upper side facing the smoke detector to which the cover is attached; and a fitting structure that includes a first fitting part that fits into the smoke inlet to restrict the rotational movement of the dustproof cover about the vertical axis when the dustproof cover is attached to the smoke detector, and a second fitting part that fits into the smoke inlet to restrict the downward movement of the dustproof cover. As a result, the fitting force that affects the rotational movement involved when the dustproof cover is rotated off the smoke detector can be adjusted by the first fitting part, and the fitting force that affects the downward movement involved when the dustproof cover is unintentionally removed from the smoke detector can be adjusted by the second fitting force. Thus, it is possible to independently adjust the fitting force that affects the rotational movement involved when the dustproof cover is rotated off the smoke detector and the fitting force that affects the downward movement involved when the dustproof cover is unintentionally removed from the smoke detector.

[0018] That is, the fitting structure of the present invention has a structure that enables both ensuring the fitting force of the dust-proof cover to such an extent that the dust-proof cover does not come off from the smoke detector at an unintended timing and easily removing the dust-proof cover from the smoke detector by rotating the dust-proof cover.

[0019] (Effect of the removal structure of the dust-proof cover) In addition, when a rotational force exceeding the rotational force in the rotational direction regulated by the first fitting portion is applied to the dust-proof cover in the fitting structure, the side end portion of the first fitting portion abuts against the side end portion of the smoke inlet, and the first fitting portion is deformed, so that the fitting of the first fitting portion and the second fitting portion is released and the dust-proof cover can be removed from the smoke detector. Therefore, in accordance with the release of the fitting by the first fitting portion, the fitting by the second fitting portion is also released, making it possible to easily remove the dust-proof cover from the smoke detector.

[0020] (Effect of the fitting structure provided with the fitting recess and the fitting claw portion) In addition, the first fitting portion is formed on the side surface of the cover main body portion so as to project inward in an annular shape at a predetermined interval in a plan view, and the upper end side fits into the smoke inlet to fit into the smoke inlet and regulate the movement in the rotational direction. The second fitting portion is formed to project further inward from the predetermined fitting recess, and the lower end side abuts against the lower end side of the smoke inlet and fits into the smoke inlet to fit into the smoke inlet and regulate the downward movement. Therefore, it is possible to individually adjust the fitting force of the fitting recess by the amount of projection inward, the lateral width in the rotational direction, the vertical width in the vertical direction, etc., and the fitting force of the fitting claw portion by the amount of projection inward, the lateral width, the vertical width, etc. of the fitting claw portion.

[0021] (Effect of the arrangement of the fitting recess and the fitting claw portion) In addition, the fitting recesses are formed at four locations on the side surface of the cover main body portion at a predetermined interval in an annular shape in a plan view, and the fitting claw portions are formed in at least two opposing fitting recesses out of the four formed fitting recesses. Therefore, it is possible to fit the fitting structure to the smoke detector in a well-balanced manner and attach the dust-proof cover.

[0022] (Effect of chamfered mating recess) Furthermore, both sides of the upper end of the fitting recess in the rotational direction are chamfered as prescribed. The fitting structure is designed so that when a rotational force exceeding the rotational force restricted by the fitting recess is applied to the dustproof cover, the chamfered portion of the fitting recess comes into contact with the side end of the smoke inlet, causing the fitting recess to deform. This releases the engagement of the fitting recess and the fitting claw, allowing the dustproof cover to be removed from the smoke detector. This weakens the restriction of rotational movement by the fitting recess, making it possible to remove the dustproof cover from the smoke detector with less force. Moreover, even if the restriction of rotational movement by the fitting recess is weakened, the engagement force of the fitting claw is not affected, so sufficient engagement force of the dustproof cover is ensured.

[0023] (Effects on the legs) Furthermore, the cover body is provided with multiple legs that extend downward from the bottom surface of the cover body, forming an annular shape in plan view at predetermined intervals. The fitting recesses are formed between the predetermined legs, and by applying a rotational force to the legs that exceeds the rotational force restricted by the fitting recesses, the fitting of the fitting recesses and the fitting claws is released, allowing the dust cover to be removed from the smoke detector. As a result, no special tool is required to apply rotational force to the dust cover when removing it from the smoke detector. The dust cover can be removed from the smoke detector simply by pushing the legs with a rod-shaped member long enough to reach the legs and applying rotational force. [Brief explanation of the drawing]

[0024] [Figure 1] This is an explanatory diagram showing a smoke detector installed on the ceiling and an unattached dust cover. [Figure 2] This is an explanatory diagram showing a smoke detector with a dust cover attached. [Figure 3] This is an explanatory diagram showing how to remove the dust cover from a smoke detector. [Figure 4] This is an explanatory diagram showing a smoke detector with its dust cover removed. [Figure 5]This is an explanatory diagram showing the dust cover from the front. [Figure 6] This is an explanatory diagram showing the dust cover as viewed from above. [Figure 7] This is an explanatory diagram showing the dust cover viewed from a diagonal downward angle. [Figure 8] This is an explanatory diagram showing the dust cover viewed from a diagonal upward angle. [Figure 9] This is a schematic diagram illustrating how a dust cover is attached to the bottom of a smoke detector. [Figure 10] This is an explanatory diagram that schematically shows the dimensional relationship between the smoke inlet of the smoke detector and the fitting structure of the dust cover, taken from the left side of the center line in Figure 9. [Figure 11] This is a schematic diagram illustrating the fitted state of the dust cover's fitting structure. [Figure 12] This is a schematic diagram illustrating the fitting portion of the dust cover and smoke detector in a plan view before fitting. [Figure 13] This is a schematic diagram illustrating the fitted portion of the dust cover and smoke detector in a plan view. [Figure 14] This is a schematic diagram illustrating, in plan view, the mating portion of the dust cover and smoke detector in the state immediately before the mating state is released. [Figure 15] This is a schematic diagram illustrating the fitting recess, fitting claw portion, and stacking recess when two dust covers are stacked on top of each other. [Figure 16] This is an explanatory diagram showing the five dust covers stacked on top of each other. [Figure 17] This is an explanatory diagram showing a laminated sheet structure using environmentally friendly resin and a reinforcing structure for the legs. [Figure 18] This is an explanatory diagram showing a smoke detector with a dust cover attached, both in its boxed state and in a horizontal position. [Modes for carrying out the invention]

[0025] Embodiments of the dust cover according to the present invention will be described below with reference to the drawings. However, the present invention is not limited to the following embodiments.

[0026] [Basic Concepts of the Embodiment] First, the basic concept of the embodiment will be explained. The embodiment generally relates to a dust cover to be attached to a smoke detector having a smoke inlet.

[0027] Here, a "smoke detector" is installed in a designated monitoring area and monitors for fires by detecting smoke generated in that area. The "monitoring area" is the area that is monitored by the smoke detector and is an outdoor or indoor space of a certain size, including areas such as rooms, corridors, and stairwells in a building.

[0028] The "dust cover" is a cover attached to the smoke detector to prevent dust and dirt from entering through the smoke inlet, and is removed from the smoke detector when monitoring by the smoke detector is started. The "dust cover" also functions as cushioning material when the smoke detector is packaged while still attached.

[0029] Furthermore, the "dustproof cover" of this embodiment includes a "fitting structure" in addition to the "cover body."

[0030] The "cover body" covers the outside of the smoke detector, including the smoke inlet, and has an opening on the upper side, which is the side to which the smoke detector is attached. In the specification and claims, the "upper side of the dust cover" is defined as the side to which the smoke detector is attached, and the opposite side is defined as the "lower side," and "height" refers to the length in the vertical direction.

[0031] The "fitting structure" is characterized by having two fitting parts, a "first fitting part" and a "second fitting part." The "first fitting part" fits into the smoke inlet when a dust cover is attached to the smoke detector, restricting the rotational movement of the dust cover with an axis in the vertical direction. The "second fitting part" fits into the smoke inlet when a dust cover is attached to the smoke detector, restricting the downward movement of the dust cover. The "first fitting part" and the "second fitting part" are provided on the dust cover corresponding to the position of the smoke inlet of the smoke detector.

[0032] Therefore, the fitting force that affects the rotational movement involved in rotating and removing the dust cover from the smoke detector is adjustable by the first fitting part, and the fitting force that affects the downward movement involved in the dust cover coming off the smoke detector unintentionally is adjustable by the second fitting force, making it possible to independently adjust the fitting force that affects the rotational movement involved in rotating and removing the dust cover from the smoke detector and the fitting force that affects the downward movement involved in the dust cover coming off the smoke detector unintentionally. In other words, the "fitting structure" of the embodiment has a structure that can achieve both ensuring a fitting force of the dust cover that prevents the dust cover from coming off the smoke detector at an unintended time and easily removing the dust cover from the smoke detector by rotating it.

[0033] Furthermore, the "fitting structure" is designed so that when a rotational force exceeding the rotational force restricted by the first fitting part is applied to the dustproof cover, the side end of the first fitting part comes into contact with the side end of the smoke inlet, causing the first fitting part to deform, thereby releasing the fitting between the first and second fitting parts and allowing the dustproof cover to be removed from the smoke detector.

[0034] Furthermore, the "fitting structure" more specifically comprises a "fitting recess" that functions as a "first fitting part" and a "fitting claw part" that functions as a "second fitting part".

[0035] The "fitting recess" is formed on the side of the cover body, protruding inward in a ring shape at predetermined intervals when viewed from above. Its upper end fits into the smoke inlet, fitting into the smoke inlet and restricting rotational movement. The number of "fitting recesses" is arbitrary, but for example, it may be formed in four locations at predetermined intervals in a ring shape when viewed from above.

[0036] The "fitting claw portion" is formed by protruding further inward from a predetermined fitting recess, and its lower end abuts against the lower end of the smoke inlet and enters the smoke inlet, thereby fitting into the smoke inlet and restricting downward movement. Furthermore, the "fitting claw portion" does not necessarily need to be formed in all fitting recesses; for example, if four fitting recesses are formed at predetermined intervals in an annular shape in a plan view, it may be formed in all four fitting recesses, or it may be formed in two opposing fitting recesses.

[0037] Furthermore, the "fitting recess" has predetermined chamfering on both sides of its upper end in the direction of rotation, and the "fitting structure" is designed so that when a rotational force exceeding the rotational force restricted by the fitting recess is applied to the dustproof cover, the chamfered portion of the fitting recess comes into contact with the side end of the smoke inlet, causing the fitting recess to deform, thereby releasing the engagement of the fitting recess and the fitting claw and allowing the dustproof cover to be removed from the smoke detector.

[0038] Furthermore, while the type of "chamfering" is arbitrary, it includes, for example, R-chamfering and C-chamfering. By applying chamfering to the fitting recess, when the dust cover is rotated, the side edge of the fitting recess can easily disengage from the side edge of the smoke inlet, thus weakening the restriction of rotational movement by the fitting recess. This makes it possible to remove the dust cover from the smoke detector with less rotational force. Moreover, even if the restriction of rotational movement by the fitting recess is weakened, it does not affect the restriction of downward movement by the fitting claw, and sufficient fitting force of the dust cover is ensured to prevent it from coming off the smoke detector unintentionally.

[0039] Furthermore, the "dust cover" is equipped with "legs," and by applying a rotational force to the legs that exceeds the rotational force restricted by the fitting recess, the dust cover can be rotated, releasing the engagement of the fitting recess and the fitting claws, making it possible to remove the dust cover from the smoke detector.

[0040] The "legs" are formed in multiple locations on the cover body at predetermined intervals in a ring shape when viewed from above, so as to protrude below the lower surface of the cover body.

[0041] Furthermore, the "fitting recess" is formed between predetermined legs when the dust cover is equipped with legs, and it is not necessarily required to be formed between all legs. For example, if four legs are formed at predetermined intervals in a ring shape in a plan view, the recess may be formed at all four locations between the legs, or it may be formed at two opposing locations between the legs.

[0042] Furthermore, because the dust cover is equipped with "legs," a special tool is not required to apply rotational force to the dust cover when removing it from the smoke detector. Instead, the dust cover can be removed from the smoke detector simply by pushing the legs with a rod-shaped member long enough to reach the legs and applying rotational force.

[0043] Furthermore, the "fitting structure" of the dust cover consists of a first fitting part (fitting recess) and a second fitting part (fitting claw) that "fit" into the smoke inlet of the smoke detector. However, the term "fitting" includes alternative terms such as engagement, locking, mounting, installation, and fixing, and in a broad sense, the "fitting structure" is a concept that includes any suitable structure that can be mechanically attached and detached.

[0044] The following describes a specific embodiment. In the specific embodiment shown below, the "first fitting part" of the fitting structure provided on the dust cover is a "fitting recess," the "second fitting part" is a "fitting claw," the "legs" are formed at four locations on the lower side of the cover body, the "fitting recesses" are formed at four locations on the side of the cover body between the legs, and the "fitting claws" are formed at two opposing fitting recesses.

[0045] [Specific details of the embodiment] The embodiments of the dust cover will be described in the following sections. a. Installation and removal of dust covers for smoke detectors. b. Structure of the dust cover c. Fitting structure of the dust cover for the smoke detector c1. Fitting structure of the smoke inlet and dust cover of the smoke detector c2. Fitting into the smoke inlet using a fitting structure c3, c3. Release of the mating state by the mating structure d. Structure of a dust cover to ensure separation d1. Stack height d2. Tapered surface e. Laminated sheet structure using environmentally friendly resin and leg reinforcement structure f. Anti-tipping structure for smoke detectors with dust covers g. Color of the dust cover h. Modified Examples of the Invention

[0046] [a. Installation and removal of dust covers for smoke detectors] First, we will explain how to attach and remove the dust cover to the smoke detector. In this explanation, please refer to Figure 1, which shows a smoke detector installed on the ceiling with an unattached dust cover; Figure 2, which shows a smoke detector with a dust cover attached; Figure 3, which shows the process of removing the dust cover from the smoke detector; and Figure 4, which shows the smoke detector with the dust cover removed.

[0047] In the explanation of Figure 1, the X, Y, and Z directions are mutually orthogonal. Specifically, when viewing the front view from the position where one fitting recess 22 on the dust cover 10 and one smoke inlet 1210 of the smoke detector 12 are centered, the X direction is the left-right direction, the Y direction is the up-down direction, and the Z direction, which is not shown in Figure 1, is the front-back direction. Furthermore, in the X direction, the +X side is the right side and the -X side is the left side, in the Y direction, the +Y side is the upper side and the -Y side is the lower side, and in the Z direction, the +Z side is the front side and the -Z side is the rear side. This is the same in Figures 2 to 6 and Figures 9 to 16.

[0048] As shown in Figure 1, for example, a ceiling member 14 is provided on the ceiling of a building construction site, and a detector base 13 for installing a smoke detector 12 is attached to the ceiling member. The smoke detector 12 is mechanically and electrically connected to the detector base 13 by fitting it into the detector base 13 from below and rotating it, and is installed on the ceiling member 14. The smoke detector 12 is also transported to the construction site with a dust cover 10 attached, and is attached to the detector base 13 with the dust cover 10 attached. It is also possible to attach the dust cover 10 to the smoke detector 12 after it has been attached to the detector base 13.

[0049] Multiple smoke inlets 1210 are formed at predetermined intervals around the lower side of the smoke detector 12, and in this embodiment, smoke inlets 1210 are formed in eight locations. In addition, an insect screen is arranged in a ring inside the smoke inlets 1210, and a smoke detection space is formed inside the insect screen, in which a labyrinth structure (a light-shielding structure that allows smoke to pass through but blocks external light) is arranged in a ring.

[0050] The smoke detection space is provided with a scattered light detection structure in which a light-emitting unit and a light-receiving unit are positioned such that the light-receiving unit's optical axis is aligned with the light-emitting unit's optical axis at a predetermined scattering angle. The smoke detector 12 detects a fire based on the signal level of the received light signal, which is detected by the light-receiving unit receiving the scattered light generated by the irradiation of smoke from the light-emitting unit onto the smoke flowing into the smoke detection space.

[0051] The dust cover 10 comprises a cover body 18, legs 20, a fitting recess 22, and a fitting claw 24.

[0052] The cover body 18 covers the outside of the smoke detector 12, including the smoke inlet 1210, when the dustproof cover 10 is attached to the smoke detector 12, and has an opening at the top. It has a bowl-like shape with a circular opening at the top to correspond to the shape of the smoke detector 12. Furthermore, unlike the outer portion of the dustproof cover in Patent Document 1, which was cited as a conventional dustproof cover, the cover body 18 does not have a flange portion that protrudes outward from around the upper opening 1810, so that dust and dirt are less likely to accumulate on the dustproof cover 10.

[0053] The legs 20 are formed in four locations on the underside of the cover body 18, rotated 90° in a ring shape when viewed from above, so that they protrude below the underside (bottom) of the cover body 18.

[0054] The fitting recesses 22 are formed inwardly at four locations on the side of the cover body 18 between the leg portions 20. Some of the fitting recesses 22 have fitting claw portions 24 that extend further inward from the fitting recess 22. The fitting claw portions 24 abut against the lower end of the smoke inlet 1210 of the smoke detector 12 and engage, so that the dustproof cover 10 remains attached to the smoke detector 12 installed on the ceiling member 14, as shown in Figure 2, and does not fall off naturally. The detailed structure of the dustproof cover 10 will be described later.

[0055] Furthermore, the dust cover 10 is attached to the smoke detector 12, which reliably prevents dust and debris from the construction site from entering the smoke detector 12 through the smoke inlet 1201, causing clogging of the insect screen, affecting the detection sensitivity of the smoke detection section, and reducing its detection function.

[0056] Furthermore, when the construction of the building is completed and the smoke detector 12 is put into use, the dust cover 10 is removed from the smoke detector 12. To remove the dust cover 10, for example as shown in Figure 3, a rod-shaped member 16 of a predetermined length that reaches the dust cover 10 attached to the smoke detector 12 is brought into contact with one of the four legs 20 provided on the dust cover 10, and a rotational force is applied to the dust cover 10 around the Y axis. As shown in Figure 4, the dust cover 10 will detach from the smoke detector 12 and fall naturally.

[0057] [b. Structure of the dust cover] Next, the structure of the dust cover will be explained. In this explanation, please refer to Figure 5, which shows the dust cover viewed from the front; Figure 6, which shows the dust cover viewed from above; Figure 7, which shows the dust cover viewed from a diagonal downward angle; and Figure 8, which shows the dust cover viewed from a diagonal upward angle. In Figures 6 to 8, a reference position marker 15, indicated by "▼", is shown as a guide to the position of the dust cover 10 when viewed from the front in Figure 5.

[0058] The dust cover 10 is manufactured, for example, by a vacuum forming method using a known convex mold, and its thickness is approximately 0.2 to 0.3 mm. Furthermore, when the leg portion 20 is manufactured by the vacuum forming method, it is a part that is prone to thinning due to deep drawing, which reduces its strength. Therefore, multiple reinforcing ribs 40 extending in the height direction (up and down direction) are formed on the leg portion 20 to increase its strength.

[0059] Furthermore, the cover body portion 18, legs 20, fitting recess 22, and fitting claw portion 24 of the dust cover 10 are basically as described above, and as shown in Figure 6, the fitting claw portion 24 is formed in the fitting recess 22 which is formed in two places, on the front and rear sides. When distinguishing the four legs 20, the right front leg is referred to as leg 20(20-1), the left front leg as leg 20(20-2), the left rear leg as leg 20(20-3), and the right rear leg as leg 20(20-4), and in Figures 5 to 8, they are referred to as legs 20(20-1) to 20(20-4).

[0060] Here, the reason why fitting claws 24 are not provided in the two fitting recesses 22 formed on the left and right sides is that the fitting claws 24 formed in the two locations on the front and rear sides are sufficient to maintain the state in which the dust cover 10 is attached so that it does not fall off the smoke detector 12 naturally. If it is desired to increase the fitting force of the dust cover 10 to the smoke detector 12, fitting claws 24 may also be formed in the two fitting recesses 22 formed on the left and right sides.

[0061] Furthermore, as shown in Figures 6 to 8, since the legs 20 are formed at four locations on the lower side of the cover body 18, a circular bottom surface 26 is formed in the center of the bottom surface of the cover body 18, and a series of bottom surfaces 28 are formed that extend in four directions from the circular bottom surface 26 toward the fitting recess 22.

[0062] Furthermore, since the leg portion 20 is formed to protrude below the bottom surface of the cover body portion 18, the bottom surface of the leg portion 20 is located below the circular bottom surface 26 and the connected bottom surface 28 (the bottom surface of the cover body portion 18), and side walls of a predetermined height are formed at the boundary between the leg portion 20 and the circular bottom surface 26 and at the boundary between the leg portion 20 and the connected bottom surface 28.

[0063] Furthermore, tapered surfaces 35 are formed at the boundaries between the four fitting recesses 22 and the connected bottom surface 28, and tapered notched surfaces 34 are formed on both sides of the upper end of the fitting recesses 22, for example, by chamfering. Details of the tapered surfaces 35 will be described later.

[0064] Furthermore, the dust cover 10 is equipped with a stack structure that ensures a spaced-out state so that other dust covers 10 do not interfere with the fitting claw portion 24 when the dust covers 10 are stacked. As shown in Figures 6 to 8, a stack recess 30 is formed on each of the leg portions 20 as part of the stack structure. When distinguishing between the four stack recesses 30, the stack recess formed on leg portion 20 (20-1) is referred to as stack recess 30 (30-1), the stack recess formed on leg portion 20 (20-2) as stack recess 30 (30-2), the stack recess formed on leg portion 20 (20-3) as stack recess 30 (30-3), and the stack recess formed on leg portion 20 (20-4) as stack recess 30 (30-4). In Figures 6 to 8, these are referred to as stack recesses 30 (30-1) to 30 (30-4).

[0065] The stack recess 30 extends from the bottom surface of the leg portion 20 toward the circular bottom surface 26 and the connected bottom surface 28 by a predetermined height. For example, the stack recess 30(30-1) and 30(30-2) are formed on the side walls at the boundary with the circular bottom surface 26 of the leg portions 20(20-1) and 20(20-2), and the stack recess 30(30-3) and 30(30-4) are formed on the side walls at the boundary with the connected bottom surface 28 of the leg portions 20(20-3) and 20(20-4).

[0066] Here, the positions in which the stack recesses 30(30-1) to 30(30-4) are formed for each of the legs 20(20-1) to 20(20-4) are all different. "The positions in which the stack recesses are formed for each leg are different" means that when the dust covers 10 are stacked by aligning the positions of the legs 20(20-1) to 20(20-4) which have different symbols, for example, when the dust covers 10 are stacked by aligning the position of the leg 20(20-2) of one dust cover 10 with the leg 20(20-1) of another dust cover 10, the stack recesses formed on the legs that are aligned at the same position will not overlap. For example, the stack recess 30(30-1) formed on the leg 20(20-1) of one dust cover 10 and the stack recess 30(30-2) formed on the leg 20(20-2) of the other dust cover 10 that are aligned at the same position will not overlap.

[0067] Furthermore, the stack height h of the stack recess 30 (height from the bottom surface of the leg portion 20 to the stack surface which becomes the top surface of the stack recess) is a predetermined height that does not exceed the height h0 from the bottom surface of the leg portion 20 to the circular bottom surface 26 and the connected bottom surface 28. When the dust covers 10 are stacked with the positions of the legs 20(20-1) to 20(20-4) which have different designations aligned, this height defines the gap in the height direction between adjacent dust covers 10. Therefore, this gap is set to a height that ensures a spaced state in which other dust covers 10 do not interfere with the fitting claw portion 24.

[0068] [c. Fitting structure of dust cover for smoke detector] Next, the fitting structure of the dust cover to the smoke detector will be described. In this description, refer to Figure 9, which schematically shows the state in which the dust cover is attached from the bottom of the smoke detector; Figure 10, which schematically shows the dimensional relationship between the smoke inlet of the smoke detector and the fitting structure of the dust cover, by taking the left side of the center line of Figure 9; Figure 11, which schematically shows the fitted state of the dust cover fitting structure; Figure 12, which schematically shows the fitting portion of the dust cover and smoke detector in the state before fitting in a plan view; Figure 13, which schematically shows the fitting portion of the dust cover and smoke detector in the fitted state in a plan view; and Figure 14, which schematically shows the fitting portion of the dust cover and smoke detector in the state just before the fitting state is released in a plan view.

[0069] Figures 9 to 11 show a cross-section of the dust cover 10 viewed from the right side, where the fitting recess 22 and fitting claw portion 24 of the dust cover 10 and the smoke inlet of the smoke detector 12 can be seen. To make the dust cover 10 and the smoke detector 12 easier to understand, the cut end face of the dust cover 10 is shown with a thick line. Figures 12 to 14 show a plan view of the fitting portion of the dust cover and the smoke detector, where the fitting recess 22 and fitting claw portion 24 of the dust cover 10 and the smoke inlet of the smoke detector 12 can be seen, and the cut end face of the dust cover 10 is shown with a thick line. Figure 12(A) shows the dust cover, and Figure 12(B) shows the smoke detector. Figure 12(B) also shows a reference position marker 17 indicated by "▽" as a guide for the position of the smoke detector 12 when viewed from the front.

[0070] (c1. Fitting structure of the smoke inlet and dust cover of the smoke detector) First, let's explain the fitting structure between the smoke inlet and dust cover of the smoke detector.

[0071] As shown in Figures 9 and 12, the smoke inlets 1210 are formed at predetermined intervals in eight locations on the frustoconical side surface of the lower part of the smoke detector 12. Figure 9 shows two smoke inlets 1210 that are located on the Z-axis and are opposite each other in the front-to-back direction.

[0072] The dust cover 10 has a fitting structure that fits into the smoke inlet 1210, which includes fitting recesses 22 and fitting claws 24. As described above, the fitting recesses 22 are formed in four places on the side of the cover body 18 between the legs 20, and the fitting claws 24 are formed in the fitting recesses 22 formed in two places on the front and rear sides.

[0073] When the dust cover 10 is attached to the lower side of the smoke detector 12, the fitting recess 22 fits into the smoke outlet 1210 at its upper end, as shown in Figure 11, restricting the rotational movement and upward movement of the dust cover 10 around the Y axis.

[0074] More specifically, when the fitting recess 22 is fitted into the smoke inlet 1210, as shown in Figure 11, the protruding upper surface 2210 on the upper end side of the fitting recess 22 comes into contact with the opening upper end surface 1212 of the smoke inlet 1210, and upward movement is restricted by the fitting recess 22.

[0075] Furthermore, as shown in Figure 13, rotational movement around the Y-axis is restricted by one side end of the fitting recess 22 contacting one side end of the smoke inlet 1210. As shown in Figure 13, the width (length in the rotational direction) of the fitting recess 22 is shorter than the width (length in the rotational direction) of the smoke inlet 1210. Therefore, rotational movement of the dust cover 10 is permitted by the amount obtained by subtracting the width (circumferential direction) of the fitting projection 22 from the width (circumferential direction) of the smoke inlet 1210. Any rotational movement of the dust cover 10 exceeding this length is restricted by the fitting recess 22.

[0076] Furthermore, when the dust cover 10 is attached from the lower side of the smoke detector 12, the fitting claw portion 24 enters and fits into the smoke outlet 1210, as shown in Figure 11, thereby restricting the downward movement of the dust cover 10.

[0077] More specifically, when the fitting recess 22 is fitted into the smoke inlet 1210, as shown in Figure 11, the lower end of the fitting claw portion 24 comes into contact with the lower end surface 1214 of the opening of the smoke inlet 1210, and downward movement is restricted by the fitting claw portion 24.

[0078] (c2. Fitting to the smoke inlet using a fitting structure) Next, we will explain how the fitting structure is used to fit the smoke inlet.

[0079] In this explanation, as shown in Figure 10, the height from the protruding upper surface 2210 of the fitting recess 22 to the connected bottom surface 28 which is the bottom surface of the cover body 18 is defined as h1, and the height from the protruding upper surface 2210 of the fitting recess 22 to the lower end of the fitting claw 24 is defined as h2.

[0080] Furthermore, the height from the upper end surface 1212 of the smoke inlet 1210 to the bottom surface of the smoke detector 12 (the outer bottom surface of the smoke detector 12) is defined as h3, and the height from the upper end surface 1212 of the smoke inlet 1210 to the lower end surface 1214 of the smoke inlet 1210 is defined as h4.

[0081] Furthermore, when the dust cover 10 is attached from the bottom of the smoke detector 12, the length L of the front-to-back length of the protruding upper surface 2210 of the fitting recess 22 is set such that the extension line of the protruding inner surface 2212 of the fitting recess 22 passes through approximately the midpoint P of the outer opening surface of the smoke inlet 1210.

[0082] Here, when attaching the dust cover 10 from the bottom of the smoke detector 12, in order to bring the protruding upper surface 2210 on the upper end of the fitting recess 22 into contact with the upper end surface 1212 of the opening of the smoke inlet 1210, and the lower end of the fitting claw portion 24 into contact with the lower end surface 1214 of the opening of the smoke inlet 1210, it is necessary to set heights h1 and h3 to the same height, and heights h2 and h4 to the same height.

[0083] When dimensions are set such that heights h1 and h3 are the same, and heights h2 and h4 are the same, and the dust cover 10 is attached to the bottom of the smoke detector 12, first the upper end of the fitting recess 22 enters the smoke inlet 1210 so that the protruding inner surface 2212 passes through approximately the midpoint P of the outer opening surface of the smoke inlet 1210. Subsequently, the upper end of the fitting claw portion 24 formed on the protruding inner surface 2212 contacts point Q of the curved corner of the outer bottom surface of the smoke detector 12. When the dust cover 10 is further pushed up while the upper end of the fitting claw portion 24 is in contact with point Q, the fitting claw portion 24 deforms and enters the smoke inlet 1210.

[0084] The dust cover 10 is then pushed up until the protruding upper surface 2210 on the upper end of the fitting recess 22 contacts the upper end surface 1212 of the smoke inlet 1210. At this position, the fitting recess 22 restricts upward movement, and the fitting claw portion 24 contacts the lower end surface 1214 of the smoke inlet 1210, restricting downward movement. As shown in Figure 11, the dust cover 10 is then attached to the smoke detector 12.

[0085] Here, the fitting force required to maintain the dust cover 10 attached to the smoke detector 12 is related to the fitting force of the fitting claw portion 24 that restricts downward movement. The fitting force of the fitting claw portion 24 can be changed by adjusting the vertical width (length in the vertical direction), horizontal width (length in the rotational direction), and depth width (amount of inward protrusion) of the fitting claw portion 24. To strengthen the fitting force of the fitting claw portion 24, for example, the depth width of the fitting claw portion 24 can be increased.

[0086] Furthermore, although heights h2 and h4 are set to the same height, height h4 may be made higher than height h2. Even if height h4 is made higher than h2, the protruding upper surface 2210 on the upper end of the fitting recess 22 abuts against the upper opening surface 1212 of the smoke inlet 1210, thereby restricting upward movement. This prevents the dust cover 10 from being pushed up more than necessary when attaching the dust cover 10 from below the smoke detector 12. Also, after the dust cover 10 is attached to the smoke detector 12, the lower end of the fitting claw portion 24 abuts against the lower opening surface 1214 of the smoke inlet 1210, restricting downward movement, thus maintaining the state in which the dust cover 10 is attached to the smoke detector 12. Moreover, even if height h4 is made higher than h2, it does not affect the function of restricting rotational movement by the fitting recess 22.

[0087] (c3. Release of the mating state by the mating structure) Next, we will explain how to release the mating state using the mating structure.

[0088] As shown in Figure 12, when the dust cover 10 is attached to the smoke detector 12 with the reference position markers 15 and 17 aligned to the same position, the fitting recesses 22 fit into the four smoke inlet 1210 locations (top, bottom, left, and right), as shown in Figure 13.

[0089] To remove the dust cover 10 from the smoke detector 12, that is, to release the fitting structure from the smoke inlet, the dust cover 10 is rotated clockwise relative to the smoke detector 12, for example, as shown in Figure 14.

[0090] When the dust cover 10 is rotated clockwise relative to the smoke detector 12, one side end of the fitting recess 22 comes into contact with one open side end of the smoke inlet 1210. Furthermore, when a rotational force exceeding the rotational force restricted by the fitting recess 22 is applied to the dust cover 10, one side end of the fitting recess 22 that is in contact with the open side end of the smoke inlet 1210 deforms so as to be pushed outward, releasing the fitting of the fitting recess 22. As the fitting recess 22 deforms, the fitting claw portion 24 also moves to the outside of the smoke inlet 1210, releasing the fitted state, and the dust cover 10 is removed from the smoke detector 12.

[0091] Furthermore, in order to apply a rotational force to the dust cover 10 that exceeds the rotational force restricted by the fitting recess 22, as shown in Figure 3, the rod-shaped member 16 can be brought into contact with any of the legs 20 of the dust cover 10 and pushed in the rotational direction. This makes it possible to remove the dust cover 10 from the smoke detector 12 without requiring a special jig for removing the dust cover from the smoke detector.

[0092] Furthermore, as shown in Figure 6, tapered notches 34 are formed on both sides of the upper end of the fitting recess 22. The presence of these tapered notches 34 makes it easier for the fitting recess 22 to be pushed outward from the smoke inlet 1210 when one side end of the fitting recess 22 comes into contact with the opening end of the smoke inlet 1210, allowing the dust cover 10 to be removed from the smoke detector 12 with less force.

[0093] In other words, the fitting force that affects the rotational direction when removing the dust cover 10 from the smoke detector 12 is related to the fitting force by the fitting recess 22 that restricts movement in the rotational direction. The fitting force by the fitting recess 22 can be changed by adjusting the vertical width (length in the vertical direction), horizontal width (length in the rotational direction), depth width (amount of inward protrusion) of the fitting recess 22, and the presence or absence of the tapered notch surface 34. To make it easier to remove the dust cover 10 from the smoke detector 12, for example, a tapered notch surface 34 can be provided or the depth width of the fitting recess 22 can be reduced.

[0094] [d. Structure of the dust cover to ensure separation] Next, the structure of the dust cover for ensuring separation will be described. In this description, refer to Figure 15, which schematically shows the fitting recess, fitting claw portion, and stack recess when two dust covers are stacked, and Figure 16, which shows the state when five dust covers are stacked. Note that Figure 15 shows the dust cover 10 in a transparent view from the right side so that the fitting recess, fitting claw portion, and stack recess are visible.

[0095] (d1. Stack height) First, let's explain the stack height of the stack recess.

[0096] As described above, a stack recess 30 is formed in each of the legs 20, and the stack height h of the stack recess 30 is a predetermined height that does not exceed the height h0 from the bottom surface of the leg 20 to the circular bottom surface 26 and the connected bottom surface 28.

[0097] Furthermore, as shown in Figure 15, when dust cover 10(10-2) is rotated 90°, 180°, or 270° clockwise relative to dust cover 10(10-1), and stacked with dust cover 10(10-1) on the bottom and dust cover 10(10-2) on top, the stack surface of the stack recess 30 of dust cover 10(10-1) abuts against the lower surface of the leg portion 20 of dust cover 10(10-2), and a gap in the height direction corresponding to the stack height h is formed between dust covers 10(10-1) and 10(10-2). Note that in Figure 15, stack recesses 30(30-1) and 30(30-4) are shown as representative examples of stack recesses 30.

[0098] The gap in the height direction between the dust covers 10(10-1) and 10(10-2) corresponding to this stack height h needs to be high enough to ensure that the fitting claw portion 24 of the lower dust cover 10(10-1) does not interfere with the upper dust cover 10(10-2), as shown in the enlarged section of part B. Therefore, the stack height h must be a predetermined height that does not exceed the height h0 from the bottom surface of the leg portion 20 to the circular bottom surface 26 and the connected bottom surface 28, and it must be high enough to ensure this separated state.

[0099] (d2. Tapered surface) Next, the tapered surface will be described. The tapered surface 35 formed at the boundary between the fitting recess 22 and the connected bottom surface 28 makes it possible to reduce the gap in the height direction of the dust cover corresponding to the stack height h.

[0100] Here, as shown in Figure 15, when dust covers 10(10-1) and 10(10-2) are stacked, if a tapered surface 35 is not formed at the boundary between the fitting recess 22 and the connected bottom surface 28, in order to ensure a spaced state where the fitting claw portion 24 does not interfere, the connected bottom surface 28 of the upper dust cover 10(10-2) must be positioned above the fitting claw portion 24 of the lower dust cover 10(10-1).

[0101] In other words, by forming a tapered surface 35 at the boundary between the fitting recess 22 and the connected bottom surface 28, it is possible to reduce the gap in the height direction of the dust cover 10(10-1) and 10(10-2) compared to the case where the tapered surface 35 is not formed, thereby ensuring a spaced state in which the fitting claw portion 24 does not interfere with each other. Furthermore, since the gap in the height direction of the dust cover 10(10-1) and 10(10-2) corresponds to the stack height h, the presence of the tapered surface 35 in the dust cover 10 reduces the stack height h, and the height h0 from the bottom surface of the leg portion 20 to the circular bottom surface 26 and the connected bottom surface 28 can also be set lower, making it possible to reduce the size of the dust cover 10.

[0102] Furthermore, the dust covers 10 are stacked in multiple layers, for example, during the manufacturing process or when they are being packaged. The gap in the height direction of the dust covers (stack height h) naturally affects the stacking height of the stacked dust covers 10. For example, in Figure 16, where five dust covers 10 are stacked, if the height of one dust cover 10 is H, the stacking height H of the stacked dust covers 10 is H + 4h. In the "4h" portion, which is four stack heights, the presence or absence of the tapered surface 35 makes a difference.

[0103] Furthermore, the position in which the fitting claw portion 24 is formed relative to the fitting recess 22 also affects the gap in the height direction of the dust cover while ensuring a separated state. Since the fitting claw portion 24 is formed in approximately the lower half of the fitting recess 22, it is possible to reduce the gap in the height direction of the dust cover 10 and ensure a separated state in which the fitting claw portion 24 does not interfere.

[0104] [e. Laminated sheet structure using environmentally friendly resin and leg reinforcement structure] Next, we will describe the laminated sheet structure using environmentally friendly resin and the leg reinforcement structure. In this description, please refer to Figure 17, which shows the laminated sheet structure using environmentally friendly resin and the leg reinforcement structure. Figure 17(A) shows the laminated sheet structure using environmentally friendly resin, and Figure 17(B) shows the leg reinforcement structure.

[0105] As shown in Figure 17(A), the dust cover 10 has a laminated sheet structure using environmentally friendly resin. The environmentally friendly resin layer 36 is a layer of resin obtained by mixing a predetermined synthetic resin such as polypropylene with a predetermined non-synthetic resin such as calcium carbonate, starch, or cellulose. For example, an environmentally friendly resin is used that contains 49% by weight of propylene and 51% by weight of calcium carbonate. By using such an environmentally friendly resin, the amount of petroleum-derived resin used can be reduced compared to conventional dust covers, contributing to the reduction of CO2 emissions.

[0106] Furthermore, the laminated sheet structure has a structure in which polypropylene layers 38 are arranged as synthetic resin on both sides of the environmentally friendly resin layer 36. When the dust cover 10 is attached to the smoke detector 12, the environmentally friendly resin layer 36 containing calcium carbonate does not come into direct contact with the smoke detector 12. This prevents chemicals used in the manufacture of the environmentally friendly resin layer 36, or liquids from which components of the environmentally friendly resin have leached out due to moisture such as condensation, from coming into contact with the smoke detector 12, thereby eliminating any impact on the smoke detector 12. In addition, the intrusion of material-specific powders such as paper dust generated from the mixed non-synthetic resins is prevented, thereby eliminating any impact on the smoke detector 12.

[0107] Furthermore, the dust cover, which has a laminated sheet structure consisting of an environmentally friendly resin layer 36 and a polypropylene layer 38, is heavier than the conventional dust cover made of polystyrene. The dust cover with the laminated sheet structure of the environmentally friendly resin layer 36 and polypropylene layer 38 weighs approximately 5.1 grams, while the dust cover made of polystyrene weighs approximately 3.7 grams. Therefore, as shown in Figure 4, when the dust cover 10 is removed from the smoke detector 12 and dropped, the dust cover 10 falls to a position close to the smoke detector 12 in a plan view, allowing for quick recovery of the removed dust cover 10.

[0108] Furthermore, as mentioned above, when the dust cover 10 is manufactured using a vacuum forming method with a convex mold, the legs 20 are easily made thin by deep drawing. In addition, since an environmentally friendly resin that is softer than the synthetic resins such as polystyrene that were conventionally used is used, the strength of the legs 20 will be further reduced.

[0109] Therefore, as shown in Figure 17(B), the strength of the leg portion 20 is reinforced by forming multiple reinforcing ribs 40 that extend in the height direction on the outer circumferential surface of the leg portion 20, which is a part that is prone to thinning.

[0110] [f. Structure to prevent tipping of smoke detectors with dust covers attached] Next, we will explain the structure for preventing the smoke detector with a dust cover from tipping over. For this explanation, please refer to Figure 18, which shows the smoke detector with a dust cover attached in both its boxed state and in a horizontal position. Figure 18(A) shows the smoke detector with a dust cover attached in its boxed state, and Figure 18(B) shows the smoke detector with a dust cover attached in a horizontal position.

[0111] As shown in Figure 18(A), the smoke detector 12 is packed in a packaging box 42 with the dust cover 10 attached and transported to the construction site. When packing the smoke detector 12 with the dust cover 10 attached into the packaging box 42, the smoke detector 12 is packed horizontally so that the top surface of the smoke detector 12 (the side that is attached to the detector base 13) is at a predetermined angle to the bottom surface of the packaging box, and the dust cover 10 also functions as cushioning material.

[0112] As described above, when packing the smoke detectors 12 into boxes, the smoke detectors 12 with the dust cover 10 attached may be placed horizontally. Therefore, as shown in Figure 18(B), the smoke detectors 12 with the dust cover 10 attached are supported at three points: two of the four legs 20 that make contact with the workbench 44 (the surface on which the smoke detectors 12 with the dust cover 10 are placed), and P3 near the side wall on the opening side of the cover body 18. This makes it possible to keep the smoke detectors 12 with the dust cover 10 attached in a horizontal position without them tipping over, thereby improving the work efficiency of packing and other operations.

[0113] [g. Color of the dust cover] Next, let's explain the color of the dust cover. The dust cover 10 is a predetermined chromatic color that is different from the color of the ceiling and walls of the construction site where the smoke detector 12 is installed. Here, since the ceiling and walls of the construction site where the smoke detector 12 is installed are often achromatic colors such as black, gray, or white, the dust cover 10 is a chromatic color that is different from the color of the installation environment, for example, a yellowish chromatic color.

[0114] Therefore, the dust cover 10 attached to the smoke detector 12 is conspicuously visible at the construction site, making it possible to prevent forgetting to remove the dust cover 10 and to easily retrieve the dust cover 10 if it falls off the smoke detector 12.

[0115] [h. Variations of the present invention] Modifications of the dust cover according to the present invention will now be described. In addition to the embodiments described above, the dust cover of the present invention includes the following modifications.

[0116] (leg) In the above embodiment, the legs are formed at four locations on the underside of the cover body, rotated 90° in a ring shape in a plan view. However, the embodiment is not limited to this, and for example, the legs may be formed at three locations on the underside of the cover body, rotated 120° in a ring shape in a plan view. If the legs are formed at three locations, for example, fitting recesses are formed at three locations between the legs, and fitting claws are formed in the three fitting recesses.

[0117] Furthermore, the number and position of the legs, fitting recesses, and fitting claws correspond to the number and shape of the smoke inlets formed in the smoke detector 12. A dust cover with legs and fitting recesses (fitting claws) formed in three locations by rotating them 120° in a ring shape corresponds to a smoke detector where, for example, the number of smoke inlets 1210 is a multiple of three, such as three or six.

[0118] (Color of the dust cover) In the above embodiment, the dust cover was made easily identifiable by using a predetermined chromatic color different from the color of the installation environment. However, a phosphorescent material may be added to the synthetic resin on the surface of the dust cover. This would make it even easier to identify the dust cover.

[0119] (Dust cover made with environmentally friendly resin) In the above embodiment, a laminated sheet structure using environmentally friendly resin is used, but it is not limited to this. A single-material environmentally friendly resin sheet material or a composite material of synthetic resin and environmentally friendly resin may be used as a single-layer sheet. In this case, since the dust cover comes into direct contact with the smoke detector, the influence of chemicals emitted from the environmentally friendly resin and components leached from the environmentally friendly resin due to condensation cannot be excluded, but it can be used if the influence of leached components is acceptable.

[0120] Furthermore, biodegradable resins (resins that decompose under specific conditions) and recycled resins may be used as environmentally friendly resins. For example, biomass-derived biodegradable resins include polylactic acid (PLA), polyhydroxyalkanoate (PHA), and polybutylene succinate (PBS), while fossil resource-derived biodegradable resins include polybutylene adipate terephthalate (PBAT) and polycaprolactone (PCL).

[0121] (others) Furthermore, the present invention includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the numerical values ​​shown in the above embodiments. [Explanation of Symbols]

[0122] 10,10(10-1),10(10-2): Dust cover 12: Smoke detector 1210: Smoke inlet 1212: Opening top surface 1214: Opening bottom end surface 131212 Detector Base 14: Ceiling components 15,17: Reference position marker 16: Rod-shaped member 18: Cover body 1810:Top opening 20,20(20-1)~20(20-4): Legs 22: Fitting recess 2210: Overhang top surface 2212: Overhanging inner surface 24: Engagement claw 26: Circular base 28: Continuous bottom surface 30,30(30-1)~30(30-4): Stack recess 34: Tapered notch surface 35: Tapered surface 36: Environmentally friendly resin layer 38: Polyprene layer 40: Reinforcement Ribs 42: Packaging box 44: Workbench

Claims

1. A dust cover that can be attached to and removed from a smoke detector, A cover body that covers the outside of the smoke detector, including the smoke inlet, and has an opening on the upper side that faces the smoke detector to be mounted, When the dust cover is attached to the smoke detector, the fitting structure includes a first fitting portion that fits into the smoke inlet and restricts the rotational movement of the dust cover about the vertical axis, and a second fitting portion that fits into the smoke inlet and restricts the downward movement of the dust cover. A dust cover characterized by having a feature.

2. A dust cover according to claim 1, The fitting structure is characterized in that, when a rotational force exceeding the rotational force restricted by the first fitting portion is applied to the dust cover, the side end of the first fitting portion abuts against the side end of the smoke inlet, causing the first fitting portion to deform, thereby releasing the fitting of the first fitting portion and the second fitting portion, and allowing the dust cover to be removed from the smoke detector.

3. A dust cover according to claim 1, The first fitting portion is a fitting recess formed on the side surface of the cover body portion, protruding inward in an annular shape at a predetermined interval in plan view, with its upper end fitting into the smoke inlet and restricting movement in the rotational direction. The dust cover is characterized in that the second fitting portion is formed by protruding further inward from a predetermined fitting recess, and its lower end abuts against the lower end of the smoke inlet and enters the smoke inlet, thereby fitting into the smoke inlet and restricting its downward movement.

4. A dust cover according to claim 3, The aforementioned fitting recesses are formed in four locations on the side surface of the cover body at predetermined intervals in an annular shape when viewed from above. The dust cover is characterized in that the fitting claw portion is formed in at least two opposing fitting recesses among the four fitting recesses formed therein.

5. A dust cover according to claim 3, Both sides of the upper end of the fitting recess in the rotational direction are chamfered to a predetermined degree. The aforementioned fitting structure is characterized in that, when a rotational force exceeding the rotational force restricted by the fitting recess is applied to the dust cover, the chamfered portion of the fitting recess comes into contact with the side end of the smoke inlet, causing the fitting recess to deform, thereby releasing the fitting of the fitting recess and the fitting claw and allowing the dust cover to be removed from the smoke detector.

6. A dust cover according to claim 5, further, Multiple legs are provided on the cover body at predetermined intervals in a ring shape when viewed from above, so as to protrude below the lower surface of the cover body. The fitting recess is formed between predetermined legs, A dust cover characterized in that the dust cover can be removed from the smoke detector by applying a rotational force to the leg portion that exceeds the rotational force restricted by the fitting recess portion, thereby rotating the dust cover and releasing the engagement of the fitting recess portion and the fitting claw portion.

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