Support device for noise absorption device

Abstract

To provide a support device that increases support strength when a noise absorption device allowing an electric wire to be wound therearound is supported on a substrate, and facilitates operations to wind the electric wire around the noise absorption device.SOLUTION: A support device 1 supports a noise absorption device 2 on a substrate. The noise absorption device 2 comprises a cylindrical core case 3, and the core case 3 includes a pair of divided cases 3A, 3B having a semi-cylindrical shape. The divided cases 3A, 3B are connected at a connection part 34 and openable and closable. The support device 1 includes a fitting piece part 11 fitted to one divided case 3A from an outer peripheral surface side, and a pair of leg piece parts 12 connected to both ends of the fitting piece part 11. One end of the leg piece part 12 connected to the fitting piece part 11 is an easy bending part 13 that is bendable, and the other end is a fixation part 17 fixed to the substrate. When the other divided case 3B is opened, the leg piece parts 12 are also opened, and thus the divided case 3B and the leg piece parts 12 do not obstruct winding of the electric wire.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a noise absorbing device that absorbs noise currents (noise) flowing through electric wires (cables) of electronic devices, and more particularly to a support device for supporting a noise absorbing device on a substrate (including a chassis, panel, and other members). [Background technology]

[0002] A noise absorbing device that absorbs noise flowing through an electric wire has been proposed, which has a semi-cylindrical ferrite core held in a pair of openable and closable resin core cases, and an electric wire is inserted into the core cylinder of the ferrite core that is formed when the core cases are closed. A support device for supporting this type of noise absorbing device on a substrate such as a chassis or panel has also been proposed.

[0003] The applicant has previously proposed support devices for noise absorbing devices in Patent Documents 1 and 2. The support device in Patent Document 1 includes a holding part that holds the noise absorbing device so as to surround the periphery of the noise absorbing device, and a fixing part for fixing the noise absorbing device to a substrate at a position below the holding part. The holding part is formed in an upward U-shape into which the noise absorbing device can be inserted, and the upper opening of the holding part is closed with a tiltable upper side part, so that the noise absorbing device is embraced by the holding part.

[0004] Also, the support device of Patent Document 2 is also equipped with a retaining portion and a fixing portion, but the retaining portion has a pair of side pieces erected opposite each other on either side of the bottom plate, and is configured to insert the noise absorbing device in a press-fit state through an opening formed between the opposing surfaces of the pair of side pieces and elastically clamp it. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-254762 A [Patent Document 2] JP 2020-191314 A [Patent Document 3] JP 2005-197552 A Summary of the Invention [Problem to be solved by the invention]

[0006] When inserting an electric wire into this type of noise absorbing device, as in Patent Document 3, the electric wire may be wound around the noise absorbing device. That is, by winding the electric wire in a loop shape, the electric wire is inserted into the noise absorbing device twice, thereby enhancing the noise absorbing effect of the electric wire. When winding the electric wire around the noise absorbing device in this way, it becomes difficult to hold the noise absorbing device in the holding part of the supporting device in the supporting device of Patent Document 1. That is, by winding the electric wire, the outer diameter dimension of the noise absorbing device becomes large, making it difficult to hold it in the holding part. In this case, it is possible to wind the electric wire while the noise absorbing device is held in the holding part, but this requires the work of inserting the electric wire into the central opening of the noise absorbing device twice, which reduces workability.

[0007] On the other hand, in the support device of Patent Document 2, even if an electric wire is wound around the noise absorbing device, it is possible for the noise absorbing device to be held by the holding part. However, since the support device is configured to be supported by a pair of side pieces with the upper part of the holding part open, when an external force is applied to the noise absorbing device or the electric wire, the noise absorbing device is likely to fall off the holding part. Therefore, there is an issue with the support strength of the support device.

[0008] An object of the present invention is to provide a support device for a noise absorbing device which increases the support strength of the noise absorbing device and facilitates the winding of electric wires around the noise absorbing device. [Means for solving the problem]

[0009] The present invention is a support device for supporting a noise absorbing device on a substrate, the noise absorbing device comprising a cylindrical core case with a core housed therein, the core case comprising a pair of semi-cylindrical split cases supporting split cores obtained by dividing the core, the pair of split cases being connected to each other at a connecting portion provided on an edge in the circumferential direction, and the connecting portion being elastically deformable to open and close. The support device comprises a fitting piece that is fitted to one of the pair of split cases from the outer circumferential surface side, and a pair of leg pieces connected to both ends of the fitting piece, one end of the leg piece connected to the fitting piece is configured as an easily bendable portion that can be bent relative to the fitting piece, and the other end is configured as a fixed portion that is fixed to the substrate.

[0010] In the present invention, it is preferable that the pair of split cases have steps on the edge where the connecting portion is provided and on the edge on the opposite radial side, and that the engaging piece portion of the support device has a locking protrusion near the easy-to-bend portion that can engage with the step portion of the core case, and that when the engaging piece portion is engaged with the outer peripheral surface side of one of the split cases, the locking protrusion is locked with the corresponding step portion.

[0011] In addition, in the present invention, when the fitting piece is fitted into one of the separate cases and the other separate case is open relative to the one separate case, it is preferable that the leg piece of the pair of leg pieces located on the connecting portion side is bent so as to fit along the outer peripheral surface of the other separate case. Effect of the Invention

[0012] According to the present invention, when the fitting piece is fitted into one of the separate cases, the corresponding leg piece is also opened when the other separate case is opened. This makes it easier to wind the wire around one separate case without the other separate case getting in the way. In addition, since the noise absorbing device can be fixed to the board while being held by the fitting piece and the pair of leg pieces, the support strength of the noise absorbing device can be increased. [Brief description of the drawings]

[0013] [Figure 1]FIG. 2 is an external perspective view of a support device for a noise absorbing device according to the present invention. [Diagram 2] FIG. 4 is a perspective view of the noise absorbing device and the supporting device separated from each other. [Diagram 3] FIG. [Figure 4] 1A is a front view of the support device, FIG. 1B is a bottom view, and FIG. 1C is an enlarged cross-sectional view taken along line cc of the front view. [Diagram 5] FIG. [Figure 6] 11 is a perspective view illustrating a procedure for supporting the noise absorbing device by the supporting device. FIG. [Figure 7] 11 is a cross-sectional view illustrating a supporting procedure. [Figure 8] FIG. 13 is an external perspective view of a supporting device according to a first modified example. [Figure 9] FIG. 11 is an external perspective view of a second modified example of the supporting device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Next, an embodiment of the present invention will be described. FIG. 1 is an external perspective view of a support device 1 of the present invention, showing a state in which a noise absorbing device 2 is supported on a substrate K. FIG. 2 is a perspective view of a state in which the support device 1 and the noise absorbing device 2 are separated. The noise absorbing device 2 is formed in a substantially cylindrical shape, and an electric wire (cable) C to be subjected to noise absorption is inserted into the central opening. Here, the electric wire C is wound so as to be inserted twice through the central opening of the noise absorbing device 2. The support device 1 is substantially inverted U-shaped, and is fitted to the outer peripheral surface side of the noise absorbing device 2 so as to sandwich the noise absorbing device 2. Then, both ends of the support device 1 are fixed to the substrate K by screws S, and the noise absorbing device 2 is supported on the substrate K by the support device 1.

[0015] 3 is a perspective view showing a part of the noise absorbing device 2 in an exploded state. The noise absorbing device 2 is composed of a resin core case 3 that is configured in a substantially cylindrical container shape when closed, and a ferrite core (hereinafter, abbreviated as "core") 4 that is fitted inside the core case 3. The core case 3 is provided with split cases 3A and 3B that are semi-cylindrical container-shaped and divided in two in the cylindrical diameter direction on a plane including the cylindrical axis. The core 4 is composed of a pair of semi-cylindrical split cores 4A and 4B that are obtained by dividing a cylindrical core in two in the cylindrical diameter direction, and are fitted inside the split cases 3A and 3B, respectively. These split cores 4A and 4B have grooves 41 formed in two places along the dividing surface of the outer circumferential surface, extending in the cylindrical axis direction.

[0016] The split cases 3A, 3B have semicircular notches 31 on both end walls in the axial direction, and by aligning these notches 31, a central opening for inserting the electric wire C is formed. Locking projections 32 for engaging with recessed grooves 41 of the split cores 4A, 4B to lock the split cores 4A, 4B are provided on the inner circumferential surface of each split case 3A, 3B near the split edge. Furthermore, a plurality of support pieces 33 for clamping the split cores 4A, 4B in the axial direction are provided on the inner circumferential surface of each split case 3A, 3B near both ends in the axial direction.

[0017] Two connecting portions 34 are formed on the opposing side edges of the split cases 3A, 3B at a required distance in the axial direction, and these connecting portions 34 are configured as connecting pieces that can be elastically deformed. The elastic deformation of these connecting portions 34 enables the split cases 3A, 3B to perform hinged operation with the connecting portions 34 as fulcrums, allowing them to open and close relative to each other. The connecting pieces serving as the connecting portions 34 have an elastic return tendency that allows them to return to a nearly straight state when bent in the thickness direction due to an elastic force in the thickness direction.

[0018] The split cases 3A and 3B are provided with a joint 35 that is joined to each other when the split cases 3A and 3B are closed with the joint 34 as a fulcrum. That is, the left edge of the split case (the second split case on the left side of FIG. 3), in other words, the side edge on the side where the joint 34 is not formed, is provided with joint protrusions 35a at two locations spaced apart from each other in the cylindrical axis direction. The right edge of the split case (the first split case on the right side of FIG. 3) 3A is provided with two joint frame portions 35b that engage with the joint protrusions 35a. These joint protrusions 35a and joint frame portions 35b are paired with each other and constitute the joint portion 35 of the core case 3. When the split cases 3A and 3B are closed by bending the joint portion 34 as shown in FIG. 2, the joint protrusions 35a and the joint frame portions 35b are joined to each other, and the split cases 3A and 3B form a core case 3 having a cylindrical outer shape, here a substantially octagonal cylindrical outer shape.

[0019] As shown in Fig. 2, in the intermediate region in the axial direction of the outer peripheral surface of the core case 3, i.e., in the region sandwiched in the axial direction by a pair of connecting parts 34 and joining parts 35, a pair of ribs 36a with a required width dimension (dimension in the axial direction of the cylinder) are formed, and a circumferential groove 36 is formed along the axial direction between these ribs 36a. In addition, in the bottom surface of each of the divided cases 3A and 3B, a pair of slits 37a are formed in the groove of the circumferential groove 36, extending in the axial direction with a required interval in the axial direction of the cylinder, and a first core pressing piece 37 having elasticity in the axial direction of the cylinder is formed between these slits 37a. In addition, in the bottom surface of each of the divided cases 3A and 3B, second core pressing pieces 38 having elasticity in the axial direction of the cylinder are formed at two places sandwiching the circumferential groove 36 in the axial direction. As shown in FIG. 3, when the split cores 4A, 4B are installed in the split cases 3A, 3B, the first core pressing piece 37 and the second core pressing piece 38 press the split cores 4A, 4B in the inward radial direction, respectively, and maintain the engagement between the groove 41 and the protrusion 32, thereby supporting the split cores 4A, 4B in the split cases 3A, 3B.

[0020] In each of the separate cases 3A, 3B, a part of the circumferential groove 36 is cut out at each portion adjacent to the connecting portion 34 and the joining portion 35, and the edges on both sides of the cut-out portion that sandwich the cut-out portion in the circumferential direction are formed as steps 39. These steps 39 have a step dimension corresponding to the plate thickness of the separate cases 3A, 3B. Therefore, when the separate cases 2A, 2B are closed to form the octagonal cylindrical core case 3, two steps 39 are arranged at two locations on the outer circumferential surface of the core case 3, i.e., at two locations that sandwich the core case 3 in the radial direction. Note that these steps 39 may be formed by thinning the wall thickness of the peripheral surface of the separate cases 3A, 3B, rather than by cutting out a portion of the separate cases 3A, 3B.

[0021] 1 is formed of an elastic resin as a strip having a substantially inverted U-shape and a required width and length. The strip width is shorter than the distance in the axial direction between the connecting portion 34 and the joining portion 35 provided in the core case 3, and longer than the length in the axial direction of the circumferential groove 36 provided in the core case 3. That is, the strip is formed to a size that does not interfere with the connecting portion 34 and the joining portion 35 so as not to impede the functions of the connecting portion 34 and the joining portion 35 even when the strip is fitted to the outer circumferential surface of the core case 3 and covers the periphery of the circumferential groove 36 as described later.

[0022] 4A is a front view of the support device 1, FIG. 4B is a bottom view, and FIG. 4C is an enlarged cross-sectional view of the line cc of the front view. The support device 1 has a fitting piece 11 curved in a shape substantially the same as the outer peripheral surface shape of the split cases 3A and 3B, i.e., the shape of an octagonal tube divided in two in the radial direction, and a pair of leg pieces 12 connected to both ends of the fitting piece 11. The portion where the fitting piece 11 and the leg piece 12 are connected is formed thin, and both leg piece parts 12 are configured as easily bent parts 13 that can be elastically bent in the plate thickness direction relative to the fitting piece 11. The easily bent parts 13 are configured so that the leg piece parts 12 are bent at a required angle, at least an angle of 120 to 140 degrees, relative to the fitting piece 11. It is preferable that the easily bent parts 13 are configured so that the leg piece parts 12 are bent to an angle of 40 to 60 degrees, which is the angle that the outer surfaces of the split cases 3A and 3B make with each other when the split cases 3A and 3B are in a mutually open state.

[0023] The dimension of the gap between the easily bendable portions 13 on both ends of the fitting piece 11 has an opening dimension that is slightly smaller than the radial dimension of the split cases 3A, 3B in the normal state. When the fitting piece 11 is fitted to the split cases 3A, 3B from the outer circumferential surface side, it is elastically deformed somewhat in the outer diametrical direction, as described below, and then elastically returns to its original shape to be elastically fitted to cover the outer circumferential surfaces of the split cases 3A, 3B.

[0024] 5 is a perspective view of the support device 1 viewed from below, and a thick-walled portion 14 having a width dimension approximately equal to that of the circumferential groove 36 of the core case 3 is formed on the inner surface of the fitting piece 11 and the leg piece 12. When the fitting piece 11 is fitted to the outer circumferential surfaces of the split cases 3A, 3B, the thick-walled portion 14 enters the circumferential groove 36 and engages with each other.

[0025] The fitting piece 11 has an opening in part of the thick-walled portion 14 at a location corresponding to the bottom of the U-shape, and a pair of case pressing pieces 15 that protrude slightly toward the inner surface are disposed facing each other within this opening. Furthermore, wedge-shaped locking projections 16 that protrude inward are formed on both ends of the thick-walled portion 14 of the fitting piece 11, i.e., on the locations close to the easily bendable portion 13. These locking projections 16 are adapted to engage with steps 39 provided on the separate case 3A or 3B from the outer diameter direction when the fitting piece 11 is fitted into the separate case 3A or 3B.

[0026] The tips of the pair of leg pieces 12, i.e., the other end opposite to the one end connected to the fitting piece 11, form a fixing part 17 which is bent outward at a substantially right angle. A fixing hole 17a of a required diameter is formed in this fixing part 17, and as shown in Fig. 1, a screw S is inserted into the fixing hole 17a for fixing to the substrate K. A metal collar may be insert-molded into this fixing hole 17a to increase the mechanical strength.

[0027] The procedure for supporting the noise absorbing device 2 configured as above on the substrate K by the support device 1 will be described. The noise absorbing device 2 is formed by assembling the split cores 4A, 4B to the split cases 3A, 3B, respectively, and then closing the split cases 3A, 3B by the connecting portion 34 to form the core case 3. At this time, before closing the split cases 3A, 3B, that is, when the split cases 3A, 3B are in an open state, as shown in FIG. 6, the fitting piece 11 of the support device 1 is fitted to one of the split cases, here the outer circumferential surface side of the first split case 3A. At this time, both ends of the fitting piece 11 are elastically deformed to be widened and fitted, and then elastically restored. The locking projections 16 near both ends are locked to the step portions 39 on both sides of the first split case 3A from the outer diameter direction, and the fitting piece 11 is attached integrally to the first split case 3A. At this time, the thick portion 14 on the inner surface of the support device 1 is fitted into the circumferential groove 36 on the outer circumferential surface of the first separate case 3A, and the fitting piece 11 is positioned in the cylindrical axis direction with respect to the first separate case 3A.

[0028] In this state, as shown in the cross-sectional view of FIG. 7(a), the second separate case 3B is held open relative to the first separate case 3A due to the elastic return behavior of the connecting portion 34 of the core case 3. Accordingly, one leg piece 12, i.e., the leg piece 12 located on the second separate case 3B side, is bent at the easy-to-bend portion 13 and held in a position along the outer circumferential surface of the second separate case 3B. In this state, the electric wire C is inserted into the inner surface side of the first separate case 3A, i.e., the central opening side. Alternatively, as shown in FIG. 6, the electric wire C is wound around the first separate case 3A. In this winding, the electric wire C is wound around the first separate case 3A and the fitting piece portion 11, but at this time, the one leg piece 12 is bent together with the second separate case 3B and is in a position retracted from the inner surface side of the first separate case 3A, so that the second separate case 3B and one leg piece 12 do not get in the way and the electric wire C can be easily wound.

[0029] Then, as shown in FIG. 7(b), the connecting portion 34 is bent to close the second separate case 3B against the first separate case 3A, and the two separate cases 3A and 3B are joined at the joint portion 35. At the same time, one leg piece 12 is elastically restored by the easily bending portion 13, and the support device 1 is restored to its U-shape. As a result, the support device 1 supports the core case 3, i.e., the noise absorbing device 2, in a state in which it is embraced inside the U-shape by the fitting piece portion 11 and the leg pieces 12 at both ends. Then, as shown in FIG. 1, the support device 1 is fixed to the board K by the screw S using the fixing holes 18 provided in the fixing portions 17 of both leg pieces 12. This fixing may be configured by screwing a screw into a female screw hole provided in the board K, or may be configured by using a nut that is screwed into a stud bolt provided upright on the board.

[0030] In this manner, the noise absorbing device 2 is supported on the substrate K by the support device 1. At this time, the core case 3, i.e., the noise absorbing device 2, is pressed by the core case pressing piece 37 provided on the fitting piece 11 and elastically contacts the substrate K, so that even if there is a dimensional difference between the noise absorbing device 2 and the support device 1, rattling when the noise absorbing device 2 is supported is prevented. Even when the electric wire C is wound around the noise absorbing device 2, the electric wire C is wound over the area between the central opening of the noise absorbing device 2 and the outer circumferential surface of the fitting piece 11 of the support device 1, so that the electric wire C is not interposed between the inner surface of the fitting piece 11 and the outer circumferential surface of the noise absorbing device 2, and the noise absorbing device 2 is supported in close contact with the inner circumferential surface of the fitting piece 11, thereby enhancing the stability of the support.

[0031] In this manner, in the support device 1 of the embodiment, when the electric wire C is inserted into or wound around the noise absorbing device 2, the pair of split cases 3A, 3B are held in an open state, so that winding the electric wire C can be performed extremely easily. Therefore, after the noise absorbing device 2 is formed into a cylindrical shape, the work of inserting the electric wire into its central opening is not required, and the work can be facilitated. In particular, the ease of the work of inserting the electric wire is improved when the electric wire is wound two or more times.

[0032] Furthermore, the support device 1 is U-shaped and is fixed to the substrate K at the leg pieces 12 at both ends while surrounding the outer periphery of the noise absorbing device 2, so that even if an external force is applied to the noise absorbing device 2 or the electric wires C, the supported state of the noise absorbing device 2 is not impaired and the support strength is increased. Furthermore, the locking projection 16 and the thick portion 14 provided on the support device 1 are locked or engaged with the step portion 39 and the circumferential groove 36 of the noise absorbing device 2, respectively, so that the noise absorbing device 2 is supported while being positioned relative to the support device 1 in the axial and circumferential directions. This increases the stability of the support of the noise absorbing device 2.

[0033] Fig. 8(a) is a perspective view of the stand device modified example 1 seen from below. In the stand device 1A of this modified example 1, the fixing parts 18 provided at the ends of the pair of leg pieces 12 have a snap structure. The tip of the leg piece 12 of the fixing part 18 is bent into an arrowhead shape in the plate thickness direction, and by inserting the bent end of the arrowhead-shaped fixing part 18 into a fixing hole H opened in the substrate K, as shown in Fig. 8(b), the step part 18a of the fixing part 18 is engaged with the inner edge of the fixing hole H, and the fixing piece part 12 can be fixed to the substrate K. After fixing, the fixing part 18 can be released from the fixing hole H by deforming the tip part 18b of the fixing part 18 in the plate thickness direction, and the stand device 1A and the noise absorbing device 2 can be removed.

[0034] Furthermore, in this support device 1A, a support protrusion 14a that protrudes in a tapered shape in the inner diameter direction is formed in part of the thick-walled portion 14 on the inner surface of each leg piece 12. This support protrusion 14a comes into contact with the side surface of the second separate case 3B when both leg pieces 12 are extended along the side surface of the noise absorbing device 2. As a result, the support protrusion 14a supports the noise absorbing device 2 from below, improving the stability of the support.

[0035] FIG. 9 is a perspective view of another modified example 2 of the support device. The support device 1B of this modified example 2 has an easily bent portion 19 of a hinge structure. The fitting piece portion 11 and the pair of leg piece portions 12 are formed as separate parts, and are connected at the connecting portion to each other to form the easily bent portion 19 of the hinge structure that is easily deformed in the plate thickness direction. For example, a cylindrical portion may be formed in each of the fitting piece portion 11 and the leg piece portion 12, and these cylindrical portions may be linearly arranged and a pin of a separate part may be inserted into the cylindrical portion. In the support device 1B of this modified example 2, since no elastic restoring force is generated in the hinge structure as the easily bent portion 19, when the split case is opened to insert or wind the electric wire, the bent leg piece portion 12 of the support device 1B is in a free state, and the split case in the open state is not closed against the intention. Therefore, the workability of inserting and winding the electric wire is improved.

[0036] The cylindrical shape of the core case of the noise absorbing device according to the present invention is not limited to the octagonal tube described in the embodiment, but may be any other polygonal tube. Alternatively, the shape of the outer circumferential surface may be a circle or a cylinder close to a circle. The shape of the fitting piece of the support device according to the present invention can be configured to any shape that corresponds to the shape of the outer circumferential surface of the cylindrical core case of the noise absorbing device. [Explanation of symbols]

[0037] 1,1A,1B Support device 2. Noise absorber 3 Core Case 3A, 3B split case 4 cores 4A, 4B split core 11 Fitting piece 12 Leg piece 13 Easy bending part (thin wall structure) 14 Thick wall part 16 Locking protrusion 17 Fixed part 18 Fixing part (snap structure) 19 Easy-to-bend section (hinge structure) 32 Locking protrusion 34 Connecting part 35 Joint 36 Circumferential groove 39 Stepped section K-substrate C Electric wire (cable)

Claims

1. A support device for supporting a noise absorbing device on a substrate, the noise absorbing device comprising a cylindrical core case with a core installed inside, the core case comprising a pair of semi-cylindrical split cases supporting split cores formed by dividing the core, the pair of split cases being connected at a connecting portion provided on the circumferential edge, the connecting portion being elastically deformable to open and close, the support device comprising a fitting piece portion that is fitted into one of the pair of split cases from the outer circumferential surface side, and a pair of leg piece portions connected to both ends of the fitting piece portion, one end of the leg piece portion connected to the fitting piece portion is configured as an easily bendable portion that can be bent relative to the fitting piece portion, and the other end of the leg piece portion is configured as a fixed portion that is fixed to the substrate.

2. A support device for a noise absorbing device as described in claim 1, wherein the pair of split cases have a step portion on the edge portion where the connecting portion is provided and on the opposite radial edge portion, and the fitting piece portion of the support device has a locking protrusion that can engage with the step portion at a position near the easily bendable portion, and when the fitting piece portion is fitted to the outer peripheral surface side of one of the split cases, the locking protrusion engages with the corresponding step portion.

3. A support device for a noise absorbing device as described in claim 2, wherein when the fitting piece portion is fitted into one of the split cases and the other split case is open relative to the one split case, the leg piece portion of the pair of leg pieces located on the connecting portion side is bent at the easy-to-bend portion so as to follow the outer peripheral surface of the other split case.

4. 4. A support device for a noise absorbing device as described in claim 3, wherein a circumferential groove is provided in a part of the outer peripheral surface of the case in the axial direction of the cylinder, and a thick portion is provided on the inner surface of the support device to be fitted into the circumferential groove, and the thick portion is fitted into the circumferential groove to position the noise absorbing device in the axial direction of the cylinder.

5. 5. The support device for a noise absorbing device according to claim 4, wherein the step portion is formed in the circumferential groove, and the locking projection is formed in a part of the thick portion.

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