Dustproof and waterproof structure and exhaust fan thereof

Abstract

The application relates to the technical field of exhaust equipment, in particular to a dustproof and waterproof structure and an exhaust fan thereof, which comprise a bearing sleeve, a bearing, a riveting sleeve and a shaft core, the bearing is arranged in the bearing sleeve, one end of the shaft core is inserted into the riveting sleeve, and the other end of the shaft core is inserted into the bearing, the riveting sleeve comprises an outer extension part and an inner extension part, the end surface of the outer extension part covers the end surface of the bearing sleeve, the inner extension part is inserted into the bearing sleeve, the outer circumferential wall of the inner extension part is provided with a spiral groove, the end surface of the bearing sleeve is provided with an annular groove, the end surface of the outer extension part of the riveting sleeve is provided with an annular flange in an extension mode, the annular flange is used for being inserted into the annular groove when being elongated, and the riveting sleeve is provided with a driving assembly used for driving the annular flange to be elongated and retracted; the stator winding is fully covered by pouring sealing glue, and the dustproof and waterproof structure and the exhaust fan thereof can avoid that dust easily causes the friction of the bearing to be increased, the stability of the fan blade rotation to be affected and the service life of the bearing to be shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of exhaust equipment, in particular to a dustproof and waterproof structure and an exhaust fan thereof. Background Art

[0002] The exhaust fan can be composed of a brushless motor, fan blades and a mounting bracket. The brushless motor includes a stator winding and a rotor. The fan blades are set in the stator winding through the rotation of the shaft core. When working, the stator winding of the brushless motor generates a rotating magnetic field, driving the rotor to rotate, and the rotor then drives the fan blades connected to it to rotate and deliver air. Usually, in order to reduce mechanical friction and wear so that the fan blades can rotate smoothly, a bearing copper sleeve and bearings are also provided between the stator winding and the shaft core of the fan blades.

[0003] Due to the use environment, exhaust fans are often exposed to dust and water ingress. On the one hand, if dust easily enters the bearings, long-term accumulation will increase the friction of the bearings, affecting the smooth rotation of the fan blades and the life of the bearings. On the other hand, if water easily enters the stator windings, it will affect the life of the stator windings. Regarding the dust prevention of the bearings of exhaust fans, the prior art patent with publication number CN217950805U proposes a dustproof structure for a fan and a fan thereof, including a bearing sleeve, a shaft core and a riveted sleeve that can be rotatably positioned in the bearing sleeve, the riveted sleeve is provided with an axially extending connecting section, the connecting section is positioned in the bearing sleeve, and the outer wall of the connecting section or the inner wall of the bearing sleeve is provided with a spiral groove. The fan includes the above-mentioned dustproof structure. The patent forms a high-pressure area and a low-pressure area in the bearing sleeve through the rotation of the spiral groove, so that dust cannot enter the high-pressure area inside the bearing sleeve from the low-pressure area outside the bearing sleeve, thereby playing the role of a spiral seal and extending the service life of the bearing. For the waterproofing of the stator winding of the exhaust fan, the prior art can use potting glue to fully cover the stator winding to meet the waterproofing requirement of 1.1m deep water. By combining the above methods, an exhaust fan with a dustproof and waterproof structure can be obtained.

[0004] However, the exhaust fan with the dustproof and waterproof structure can only prevent dust during operation. When the exhaust fan is idle, dust can still easily enter the bearing from between the riveted sleeve and the bearing copper sleeve, which can still easily lead to increased friction of the bearing, affecting the smooth rotation of the fan blades and the life of the bearing. Summary of the Invention

[0005] In order to prevent dust from easily causing increased friction in the bearings, affecting the smooth rotation of the fan blades and the life of the bearings, the present application provides a dustproof and waterproof structure and an exhaust fan thereof.

[0006] In a first aspect, the present invention provides a dustproof and waterproof structure adopting the following technical solutions:

[0007] A dustproof and waterproof structure includes a bearing sleeve, a bearing, a riveted sleeve and a shaft core, the bearing is installed in the bearing sleeve, one end of the shaft core is plugged into the riveted sleeve and the other end is plugged into the bearing, the riveted sleeve includes an outer extension and an inner extension, the end face of the outer extension covers the outside of the end face of the bearing sleeve, the inner extension is inserted into the bearing sleeve, the outer circumferential wall of the inner extension is provided with a spiral groove, the end face of the bearing sleeve is provided with an annular groove, the end face of the outer extension of the riveted sleeve is telescopically provided with an annular flange, the annular flange is used to extend into the annular groove when extended, and the riveted sleeve is provided with a driving component for driving the annular flange to extend and retract.

[0008] Preferably, both ends of the bearing sleeve are through-connected, and both end openings of the bearing sleeve are stepped from the outside to the inside with the inner diameter decreasing. Two bearings are provided, and the two bearings are respectively installed from the two ends of the bearing sleeve. The two bearings respectively abut the two stepped surfaces inside the bearing sleeve, and the shaft core is simultaneously plugged into the two bearings.

[0009] Preferably, a snap ring is sleeved on the end of the shaft core away from the rivet sleeve, and the snap ring is clamped on the outer end surface of the bearing at the far end of the rivet sleeve. A first spring is squeezed between the inner extension of the rivet sleeve and the bearing at the proximal end of the rivet sleeve, and the first spring presses the snap ring against the bearing.

[0010] Preferably, the driving assembly includes an installation box, a power supply, a telescopic driving member, a connecting rod and a second spring. The installation box is relatively fixed to the riveting sleeve, the power supply and the telescopic driving member are fixedly arranged in the installation box, the power supply is electrically connected to the telescopic driving member, the telescopic driving member is an electric cylinder, one end of the connecting rod is connected to the telescopic rod of the electric cylinder and the other end is connected to the annular flange after passing through the riveting sleeve, the electric cylinder is used to control the annular flange to actively disengage from the annular groove, one end of the second spring is fixedly connected in the installation box and the other end is fixedly connected to the connecting rod, and the second spring controls the annular flange to automatically embed into the annular groove.

[0011] Preferably, an inner annular block and an outer annular block are detachably provided on the end face of the outer extension of the riveted sleeve by screws, and an installation cavity for installing the annular flange is formed between the inner annular block and the outer annular block, and the connecting rod and the annular flange are connected in the installation cavity.

[0012] Preferably, the end of the bearing sleeve away from the riveting sleeve is equipped with a rubber sealing cover, and the rubber sealing cover is assembled after the connection between the shaft core and the bearing is completed.

[0013] Preferably, the outer end surface of the installation box is detachably provided with a cover plate, and the cover plate is provided on the power supply.

[0014] In a second aspect, the present invention provides an exhaust fan adopting the following technical solution:

[0015] An exhaust fan adopts the above-mentioned dustproof and waterproof structure, including a mounting bracket, fan blades, a stator winding and a rotor, the stator winding is fixedly set on the mounting bracket, the fan blades are riveted to the riveted sleeve, the rotor is fixedly set on the inner side of the fan blades and rotatably sleeved on the outer periphery of the stator winding, and the mounting box is fixed on the outer end of the fan blades.

[0016] Preferably, the drive assembly is provided with a remote control module, which is connected between the power supply and the electric cylinder. The remote control module, the stator winding and the main switch of the exhaust fan are signal-connected. When the main switch of the exhaust fan is turned on to energize the stator winding, the remote control module synchronously controls the electric cylinder of the drive assembly to start, and the electric cylinder actively disengages the annular flange from the annular groove. When the main switch of the exhaust fan is turned off to cut off the power to the stator winding, the remote control module synchronously controls the electric cylinder of the drive assembly to close, and the second spring automatically embeds the annular flange into the annular groove.

[0017] Preferably, a surface of the annular flange facing the annular groove is set to be a rough surface.

[0018] The beneficial effects of the present invention are:

[0019] 1. By using the drive assembly to control the annular flange of the riveted sleeve to be embedded in the annular groove of the bearing sleeve, the inside and outside of the bearing sleeve end can be isolated after the shaft core stops rotating, further preventing dust from entering, avoiding dust from easily causing increased friction of the bearing, and affecting the smooth rotation of the fan blades and the life of the bearing;

[0020] 2. When the main switch of the exhaust fan is turned off and the stator winding is powered off, the remote control module synchronously controls the electric cylinder of the drive assembly to turn off. The second spring then automatically embeds the annular flange into the annular groove, thereby achieving internal and external sealing of the bearing sleeve, achieving dust-proof effect on the bearing when the exhaust fan is idle, preventing dust from easily causing increased friction in the bearing, affecting the smooth rotation of the fan blades and the life of the bearing;

[0021] 3. When the main switch of the exhaust fan is turned off, the annular flange of the riveted sleeve can be embedded in the annular groove of the bearing sleeve, which will instantly increase the rotational resistance of the riveted sleeve and eventually quickly limit the rotation of the fan blades, achieving the effect of quickly stopping the fan blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1This is a cross-sectional view of the structure of the dustproof and waterproof structure in an idle state according to an embodiment of the present application;

[0023] Figure 2 This is a cross-sectional view of the structure of the dustproof and waterproof structure in the embodiment of the present application in a rotating state;

[0024] Figure 3 This is a cross-sectional view of the structure of the exhaust fan in the embodiment of the present application;

[0025] Figure 4 This is an external structural diagram of the exhaust fan in an embodiment of the present application.

[0026] Explanation of the accompanying drawings: 1. Bearing sleeve; 11. Rubber sealing cover; 2. Bearing; 3. Riveted sleeve; 31. Outer extension; 32. Inner extension; 4. Shaft core; 51. Retaining ring; 52. First spring; 61. Annular flange; 62. Annular groove; 71. Mounting box; 72. Power supply; 73. Electric cylinder; 74. Connecting rod; 75. Second spring; 76. Cover plate; 81. Inner annular block; 82. Outer annular block; 91. Mounting bracket; 92. Fan blades; 93. Stator winding; 94. Rotor; 95. Potting compound. DETAILED DESCRIPTION

[0027] The following will be combined with the Figure 1 -Attached Figure 4 The present invention is further described with reference to the accompanying drawings and examples.

[0028] This embodiment discloses a dustproof and waterproof structure.

[0029] Reference Figure 1 and Figure 2 The dustproof and waterproof structure includes a bearing sleeve 1, a bearing 2, a riveted sleeve 3, and a shaft core 4. The bearing sleeve 1 has two through-holes to facilitate the installation of the bearing 2 and the shaft core 4. The inner wall of the bearing sleeve 1 is a variable diameter structure. Specifically, the inner diameter of the openings at both ends of the bearing sleeve 1 is larger, while the inner diameter of the middle part is smaller, so that the openings at both ends of the bearing sleeve 1 are both stepped from the outside to the inside with the inner diameter decreasing. Two bearings 2 are provided, and the two bearings 2 are respectively installed from the two ends of the bearing sleeve 1 until they abut the stepped surface inside the bearing sleeve 1. One end of the shaft core 4 is plugged into the riveted sleeve 3, and the other end is plugged into the two bearings 2 in sequence, so that the shaft core 4 and the riveted sleeve 3 can rotate relative to the bearing sleeve 1 using the bearings 2.

[0030] Reference Figure 1 and Figure 2Furthermore, the riveted sleeve 3 includes an outer extension portion 31 and an inner extension portion 32 integrally constructed along the axial direction. The outer diameter of the outer extension portion 31 is larger than the outer diameter of the inner extension portion 32, and the inner diameter of the outer extension portion 31 is smaller than the inner diameter of the inner extension portion 32. The shaft core 4 is plugged into the outer extension portion 31 to achieve plugging with the riveted sleeve 3. The outer extension portion 31 of the riveted sleeve 3 is located outside the bearing sleeve 1, and the end surface of the outer extension portion 31 covers the outside of the end surface of the bearing sleeve 1. The inner extension portion 32 of the riveted sleeve 3 is inserted into the bearing sleeve 1, and a gap exists between the outer circumferential surface of the inner extension portion 32 and the inner circumferential surface of the bearing sleeve 1. In order to achieve stable insertion between the shaft core 4 and the bearing 2, on the one hand, a retaining ring 51 is sleeved on the end of the shaft core 4 away from the rivet sleeve 3, and the retaining ring 51 is clamped on the outer end surface of the bearing 2 at the far end of the rivet sleeve 3. On the other hand, a first spring 52 is squeezed between the inner extension 32 of the rivet sleeve 3 and the bearing 2 at the proximal end of the rivet sleeve 3. The elastic force of the first spring 52 makes the retaining ring 51 press against the bearing 2. Finally, through the arrangement of the first spring 52 and the retaining ring 51, the shaft core 4 and the bearing 2 are stably inserted.

[0031] Reference Figure 2 The outer circumferential wall of the inner extension 32 of the riveted sleeve 3 is provided with a spiral groove. During the rotation of the shaft core 4, the rotation of the spiral groove drives the surrounding air to flow to form an airflow, and forms a high-pressure area H inside the bearing sleeve 1. A low-pressure area L is formed in the gap between the end face of the bearing sleeve 1 and the end face of the outer extension 31 of the riveted sleeve 3. A pressure difference is formed between the high-pressure area H and the low-pressure area L. This pressure difference causes the dust outside the bearing sleeve 1 to encounter the resistance of the high-pressure area H and cannot enter the bearing sleeve 1, thereby achieving a dustproof effect. Specifically, the rotation direction of the spiral groove is the same as that of the shaft core 4. The above structure and principle of dynamic dustproofing are existing technologies, so they will not be elaborated on.

[0032] Reference Figure 1 and Figure 2 When the shaft core 4 stops rotating, there is no longer a high-pressure area H and a low-pressure area L inside and outside the bearing sleeve 1. At this time, dust can still easily enter the bearing 2 through the gap between the rivet sleeve 3 and the bearing sleeve 1. In order to solve the above problem, in the present invention, an annular groove 62 is provided on the end face of the bearing sleeve 1 relative to the end face of the extension 31 of the rivet sleeve 3. An annular flange 61 is provided on the end face of the rivet sleeve 3 relative to the annular groove of the bearing sleeve 1. When the annular flange 61 is extended, it is used to extend into the annular groove 62. The rivet sleeve 3 is also provided with a driving component for driving the annular flange 61 to move. The driving component is used to control the annular flange 61 of the rivet sleeve 3 to be embedded in the annular groove 62 of the bearing sleeve 1. In this way, the inside and outside of the end of the bearing sleeve 1 can be isolated after the shaft core 4 stops rotating, further preventing dust from entering, avoiding dust from easily causing increased friction of the bearing 2, and affecting the smooth rotation of the fan blade 92 and the life of the bearing 2.

[0033] Reference Figure 1 and Figure 2 The drive assembly includes a mounting box 71, a power supply 72, a telescopic drive member, a connecting rod 74, and a second spring 75. The mounting box 71 is fixed relative to the riveting sleeve 3. The power supply 72 and the telescopic drive member are fixedly arranged in the mounting box 71. The power supply 72 is electrically connected to the telescopic drive member and is used to power the telescopic drive member, which is an electric cylinder 73. In addition, a cover plate 76 is detachably provided on the outer end surface of the mounting box 71. The cover plate 76 is provided to cover the power supply 72. The provision of the cover plate 76 is used to facilitate the replacement of the power supply 72. The connecting rod 74 includes a horizontal rod and two vertical rods. The horizontal rod is horizontally connected to the telescopic rod of the electric cylinder 73. One end of each of the two vertical rods is longitudinally connected to the two ends of the horizontal rod. The other ends of the two vertical rods are connected to the annular flange 61 after passing through the riveting sleeve 3, so that the electric cylinder 73 of the drive assembly can control the annular flange 61 to actively disengage from the annular groove 62. Two second springs 75 are provided, one end of each of the two second springs 75 is fixedly connected to the mounting box 71, and the other ends of the two second springs 75 are respectively fixedly connected to the two ends of the cross bar in the longitudinal direction, so that the second spring 75 of the driving assembly can control the annular flange 61 to automatically embed into the annular groove 62.

[0034] Reference Figure 1 and Figure 2 In order to facilitate the movable installation of the annular flange 61 on the end face of the extension 31 of the riveting sleeve 3, an inner annular block 81 and an outer annular block 82 are detachably provided on the end face of the extension 31 of the riveting sleeve 3 by screws. The inner annular block 81 is closer to the axis of the riveting sleeve 3 than the outer annular block 82. An installation cavity for installing the annular flange 61 is formed between the inner annular block 81 and the outer annular block 82, and the longitudinal rod and the annular flange 61 are connected in the installation cavity.

[0035] Reference Figure 1 and Figure 2 The end of the bearing sleeve 1 away from the riveting sleeve 3 is equipped with a rubber sealing cover 11. The rubber sealing cover 11 is assembled after the connection between the shaft core 4 and the bearing 2 is completed, so as to facilitate the clamping ring 51 to be clamped between the shaft core 4 and the bearing 2. In addition, the rubber sealing cover 11 is also used to prevent dust from entering the bearing 2 from this end of the bearing sleeve 1.

[0036] This embodiment also discloses an exhaust fan, which adopts the above-mentioned dustproof and waterproof structure.

[0037] Refer to the figure to Figure 4 The exhaust fan includes a mounting bracket 91, fan blades 92, a stator winding 93 and a rotor 94. The stator winding 93 is fixedly set on the mounting bracket 91, the fan blades 92 are riveted to the riveted sleeve 3, and the rotor 94 is fixedly set on the inner side of the fan blades 92 and rotatably sleeved on the outer periphery of the stator winding 93, so that when the stator winding 93 is energized, the fan blades 92 can rotate around the shaft core 4, thereby performing exhaust work.

[0038] Reference Figure 1 As shown in the figure, the mounting box 71 is fixed to the outer end of the fan blade 92, thereby achieving relative fixation between the mounting box 71 and the riveting sleeve 3. The drive assembly is also provided with a remote control module, which is connected between the power supply 72 and the electric cylinder 73 to control the opening and closing of the electric cylinder 73. Furthermore, the remote control module, the stator winding 93 and the main switch of the exhaust fan are connected by signal, so that when the main switch of the exhaust fan is turned on to energize the stator winding 93, the remote control module synchronously controls the electric cylinder 73 of the drive assembly to start, and the electric cylinder 73 then actively disengages the annular flange 61 from the annular groove 62, thereby allowing the fan blade 92 to rotate normally. When the main switch of the exhaust fan is turned off to de-energize the stator winding 93, the remote control module synchronously controls the electric cylinder 73 of the drive assembly to close, and the second spring 75 automatically embeds the annular flange 61 into the annular groove 62, thereby achieving internal and external sealing of the bearing sleeve 1, achieving a dust-proof effect on the bearing 2 when the exhaust fan is idle, and preventing dust from easily causing increased friction of the bearing 2, thereby affecting the smooth rotation of the fan blade 92 and the life of the bearing 2. In other embodiments, the mounting box 71 of the drive assembly is provided with a control button, which is connected between the power supply 72 and the electric cylinder 73, and the control button is connected in parallel with the remote control module, so that when the remote control module fails, the opening and closing of the electric cylinder 73 can also be controlled by actively pressing the control button.

[0039] Reference Figures 1 to 4 It should be noted that turning off the exhaust fan's main switch means that the fan blades 92 need to be controlled to stop rotating. In the present invention, when the exhaust fan's main switch is turned off, the annular flange 61 of the riveted sleeve 3 can be embedded in the annular groove 62 of the bearing sleeve 1. This will instantly increase the rotational resistance of the riveted sleeve 3, ultimately quickly restricting the rotation of the fan blades 92 and achieving the effect of quickly stopping the fan blades 92. Furthermore, the side of the annular flange 61 facing the annular groove 62 is set to a rough surface to increase the roughness of the contact surface between the annular flange 61 and the annular groove 62, thereby further accelerating the stopping of the fan blades 92 when the exhaust fan is turned off.

[0040] Reference Figure 3 The stator winding 93 is fully covered by a potting compound 95 using a customized fixture, so that the stator winding 93 has a waterproof effect.

[0041] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of this application. Therefore, any equivalent changes made based on the structure, shape, and principle of this application should be included in the scope of protection of this application.

Claims

1. A dustproof and waterproof structure, characterized by: The invention comprises a bearing sleeve (1), a bearing (2), a riveted sleeve (3) and a shaft core (4), wherein the bearing (2) is installed in the bearing sleeve (1), one end of the shaft core (4) is plugged into the riveted sleeve (3) and the other end is plugged into the bearing (2), and the riveted sleeve (3) comprises an outer extension portion (31) and an inner extension portion (32), wherein the end surface of the outer extension portion (31) covers the outer end surface of the bearing sleeve (1), and the inner extension portion (32) is inserted into the inner extension portion (32). In the bearing sleeve (1), the outer circumferential wall of the inner extension (32) is provided with a spiral groove, the end face of the bearing sleeve (1) is provided with an annular groove (62), the end face of the outer extension (31) of the riveting sleeve (3) is provided with an annular flange (61) when the end face is extended, and the annular flange (61) is used to extend into the annular groove (62) when extended, and the riveting sleeve (3) is provided with a driving component for driving the annular flange (61) to extend and retract; The two ends of the bearing sleeve (1) are through-connected, and the openings at both ends of the bearing sleeve (1) are stepped from the outside to the inside, with the inner diameter decreasing. Two bearings (2) are provided, and the two bearings (2) are respectively installed from the two ends of the bearing sleeve (1). The two bearings (2) respectively abut against the two stepped surfaces inside the bearing sleeve (1), and the shaft core (4) is plugged into the two bearings (2) at the same time. A snap ring (51) is sleeved on one end of the shaft core (4) away from the riveting sleeve (3), and the snap ring (51) is clamped on the outer end surface of the bearing (2) at the distal end of the riveting sleeve (3). A first spring (52) is squeezed between the inner extension (32) of the riveting sleeve (3) and the bearing (2) at the proximal end of the riveting sleeve (3), and the first spring (52) presses the snap ring (51) against the bearing (2); The driving assembly comprises a mounting box (71), a power supply (72), a telescopic driving member, a connecting rod (74) and a second spring (75); the mounting box (71) is relatively fixed to the riveting sleeve (3); the power supply (72) and the telescopic driving member are fixedly arranged in the mounting box (71); the power supply (72) is electrically connected to the telescopic driving member; the telescopic driving member is an electric cylinder (73); one end of the connecting rod (74) is connected to the telescopic rod of the electric cylinder (73) and the other end is connected to the annular flange (61) after passing through the riveting sleeve (3); the electric cylinder (73) is used to control the annular flange (61) to actively disengage from the annular groove (62); one end of the second spring (75) is fixedly connected to the mounting box (71) and the other end is fixedly connected to the connecting rod (74); the second spring (75) controls the annular flange (61) to automatically embed into the annular groove (62); An inner annular block (81) and an outer annular block (82) are detachably provided on the end surface of the outer extension portion (31) of the riveted sleeve (3) by means of screws. A mounting cavity for mounting the annular flange (61) is formed between the inner annular block (81) and the outer annular block (82), and the connecting rod (74) is connected to the annular flange (61) in the mounting cavity.

2. The dustproof and waterproof structure according to claim 1, characterized in that: The end of the bearing sleeve (1) away from the riveting sleeve (3) is equipped with a rubber sealing cover (11), and the rubber sealing cover (11) is assembled after the connection between the shaft core (4) and the bearing (2) is completed.

3. The dustproof and waterproof structure according to claim 1, characterized in that: The outer end surface of the installation box (71) is detachably provided with a cover plate (76), and the cover plate (76) is provided to cover the power supply (72).

4. An exhaust fan, using the dustproof and waterproof structure according to claim 3, characterized in that: The invention comprises a mounting bracket (91), a fan blade (92), a stator winding (93) and a rotor (94); the stator winding (93) is fixedly arranged on the mounting bracket (91); the fan blade (92) is riveted to the riveting sleeve (3); the rotor (94) is fixedly arranged on the inner side of the fan blade (92) and rotatably sleeved on the outer periphery of the stator winding (93); and the mounting box (71) is fixed to the outer end of the fan blade (92).

5. The exhaust fan according to claim 4, characterized in that: The drive assembly is provided with a remote control module, which is connected between the power supply (72) and the electric cylinder (73). Signals are connected between the remote control module, the stator winding (93) and the main switch of the exhaust fan. When the main switch of the exhaust fan is turned on to energize the stator winding (93), the remote control module synchronously controls the electric cylinder (73) of the drive assembly to start, and the electric cylinder (73) actively disengages the annular flange (61) from the annular groove (62). When the main switch of the exhaust fan is turned off to de-energize the stator winding (93), the remote control module synchronously controls the electric cylinder (73) of the drive assembly to close, and the second spring (75) automatically embeds the annular flange (61) into the annular groove (62).

6. The exhaust fan according to claim 5, characterized in that: A surface of the annular flange (61) facing the annular groove (62) is configured as a rough surface.

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