A method for opening and closing a rice cooker lid

Abstract

The application discloses a rice cooker cover opening and closing method; the opening method comprises the following steps: (1) moving the cover upward by a certain height to avoid the cover from being limited by the inner container and the sealing element during rotation; (2) rotating and lifting the cover to make the cover no longer cover the pot body and make the inner container exposed; the closing method comprises the following steps: (1) rotating and lowering the cover to make the cover align with the pot body; (2) moving the cover downward by a certain height to make the cover cover the pot body; the automatic opening or closing of the rice cooker cover is realized, and a new use mode of the rice cooker cover is provided; further, the scheme further comprises the following steps: forming upper and lower tracks at the upper and lower shells for assembly respectively, forming two tracks by the two upper tracks and the two lower tracks respectively, and operating the supporting rod, the method has the advantages of simple control, low cost, convenient mold opening manufacturing and assembly, good firmness during use and the like.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the operation of a household appliance and its accessories, and relates to a method for automatically opening or closing a pot cover, more particularly, a method for automatically opening or closing a rice cooker cover by means of extension and rotation. PRIOR ART

[0002] The existing rice cooker has a cavity in the pot body for accommodating the inner container, and the periphery of the inner container is made into a flange, so that the inner container can be placed in the cavity with the flange exposed outside the periphery of the cavity, so that the user can lift the inner container from the pot body from the flange. In addition, the cover usually has a sealing element, which can seal the inner container in the pot body when the cover is closed. Because the inner container is higher than the periphery of the cavity and the cover has a sealing element, the cover can usually only be connected in a split or hinged manner, and the user must manually open or close it when using it, which cannot automatically open or close the cover. SUMMARY

[0003] The purpose of the present invention is to provide a rice cooker cover opening and closing method that is suitable for automatically opening or closing the cover and can avoid the influence of the inner container and the sealing element on its operation during use of the rice cooker.

[0004] The purpose of the present invention is also to provide a rice cooker cover opening and closing method that is easy to mold and assemble, and has firmness, and can provide better support to the support rod to meet the requirements of the support rod in the stroke.

[0005] The rice cooker cover opening method of the present invention can be realized by the following scheme:

[0006] A rice cooker cover opening method, characterized by comprising the following steps:

[0007] (1) Move the cover upward by a certain height to avoid the cover being restricted by the inner container and the sealing element during rotation;

[0008] (2) Rotate the cover upward so that the cover no longer blocks the pot body and the inner container is exposed for use.

[0009] The rice cooker cover opening method of the present invention can also be realized by the following scheme:

[0010] A rice cooker cover opening method, characterized by comprising the following steps:

[0011] (10) Drive the screw rod to rotate in the nut by using a motor;

[0012] (20) Fix the nut at the concentric circle of the support rod, and let the support rod move with the nut;

[0013] (30) the support rod is arranged in a pair of tracks, each of which comprises a vertical portion and an inclined portion, wherein the inclined portion is above the vertical portion;

[0014] (40) when the screw rod is rotated in a certain direction r, the protruding portion can only rise when it is in the vertical portion, and can rotate and rise when it is in the inclined portion.

[0015] (50) the support rod drives the pot cover to move away from the pot body.

[0016] Preferably, in the above-mentioned electric rice cooker cover opening method, the motor is a speed reducer, and the motor drives the screw rod to rotate through a shaft coupling.

[0017] More preferably, in the above-mentioned electric rice cooker cover opening method, a step (35) is added between step (30) and step (40).

[0018] (35) the upper and lower shells are used to assemble the components therein, and the support rod extends from the top of the upper shell; and

[0019] the lower shell is formed with two downwardly distributed lower tracks on the inside;

[0020] the upper shell is formed with two upwardly distributed upper tracks on the inside;

[0021] the upper shell and the lower shell cooperate to form the pair of tracks from the two upper tracks and the two lower tracks.

[0022] Preferably, in the above-mentioned electric rice cooker cover opening method, the upper and lower tracks and the protruding portion of step (35) are as follows:

[0023] the upper track is a downward groove;

[0024] the lower track comprises a recessed portion and an upper convex portion, the recessed portion is adjacent to the upper convex portion;

[0025] and the groove, the recessed portion and the upper convex portion form the tracks:

[0026] the left side of the recessed portion is constructed as a left side of the vertical portion of the track, serving as a first left side;

[0027] the bottom of the recessed portion is constructed as a bottom of the vertical portion of the track;

[0028] the left side of the upper convex portion is constructed as a right side of the vertical portion of the track;

[0029] the top of the upper convex portion is constructed as a lower edge of the inclined portion of the track;

[0030] the right side of the upper convex portion is constructed as an adjacent surface;

[0031] The left side of the part of the left side of the vertical part of the track is constructed by the left side of the groove;

[0032] The abutting surface is constructed by the right side of the groove as the abutting surface of the abutting surface;

[0033] The upper edge of the inclined part of the track is constructed by the bottom of the groove;

[0034] The upper shell is inserted into the lower shell with the upper convex part, wherein the first left side and the second left side form the left side of the vertical part of the track together;

[0035] The protruding part is made into a bearing seat and the ball bearing is assembled in the bearing seat.

[0036] In this way, when the two protruding parts are in the vertical parts of the two tracks and the screw rod rotates in a direction r, the support rod can only move vertically upward due to the restriction of the two vertical parts, so that the pot cover is lifted to a certain height relative to the pot body;

[0037] In addition, when the two protruding parts are in the inclined parts of the two tracks and the screw rod rotates in a direction r, the two protruding parts can rotate and rise upward along the two inclined parts, so that the support rod also rotates and rises and drives the pot cover to rotate, no longer shielding the pot body;

[0038] Furthermore, the ball bearing in the bearing seat rolls in the inclined part, which can reduce the friction of the inclined part and make the rotation and rise more smooth.

[0039] The electric rice cooker cover closing method of the present application can be realized by the following scheme:

[0040] An electric rice cooker cover closing method, characterized in that it comprises the following steps:

[0041] (1) Rotate the pot cover downward to align the pot cover with the pot body;

[0042] (2) Move the pot cover downward by a certain height to cover the pot body.

[0043] The electric rice cooker cover closing method of the present application can also be realized by the following scheme:

[0044] An electric rice cooker cover closing method, characterized in that it comprises the following steps:

[0045] (10) Drive the screw rod to rotate in the nut by using the motor;

[0046] (20) Fix the nut at the concentric circle of the support rod and make the support rod move with the nut;

[0047] (30) the support rod has a pair of protruding parts respectively in a pair of tracks containing vertical parts and slope parts, wherein the slope parts are above the vertical parts;

[0048] (40) when the screw rod rotates in a direction m, the protruding parts can rotate and descend when in the slope parts, and can only descend when in the vertical parts;

[0049] (50) the support rod drives the pot cover to move, so that the pot cover covers the pot body.

[0050] Preferably, in the above rice cooker cover closing method, the motor is a speed reducer motor, and the motor drives the screw rod to rotate through a shaft coupling.

[0051] More preferably, in the above rice cooker cover closing method, the following step (35) is added between step (30) and step (40):

[0052] (35) the upper and lower shells are used to assemble the parts therein, and the support rod extends from the top of the upper shell; and

[0053] in the lower shell, two downward tracks are formed on the left and right sides;

[0054] in the upper shell, two upward tracks are formed on the inner side;

[0055] the upper shell and the lower shell cooperate to form the pair of tracks by the two upward tracks and the two downward tracks.

[0056] Preferably, in the above rice cooker cover closing method, the upward tracks and the bearing seat of step (35) are:

[0057] the upward track is a downward groove;

[0058] the downward track contains a recessed part and an upward convex part, and the recessed part is adjacent to the upward convex part;

[0059] and the groove, the recessed part and the upward convex part form the tracks:

[0060] the left side of the recessed part is constructed as the left side of the vertical part of the track, as the first left side;

[0061] the bottom of the recessed part is constructed as the bottom of the vertical part of the track;

[0062] the left side of the upward convex part is constructed as the right side of the vertical part of the track;

[0063] the top of the upward convex part is constructed as the lower edge of the slope part of the track;

[0064] the right side of the upward convex part is constructed as the adjacent surface;

[0065] The left side of the part of the left side of the vertical part of the track is constructed by the left side of the groove;

[0066] The abutting surface is constructed by the right side of the groove;

[0067] The upper edge of the inclined part of the track is constructed by the bottom of the groove;

[0068] The upper shell is inserted into the lower shell with the upper convex part to realize the cooperation of the two, wherein the first left side and the second left side form the left side of the vertical part of the track together;

[0069] The protruding part is made into a bearing seat and the ball bearing is assembled in the bearing seat.

[0070] The direction m is just opposite to the direction r.

[0071] In this way, when the two protruding parts are in the inclined parts of the two tracks and the screw rod rotates in a direction m, the two protruding parts can rotate downward and downward along the two inclined parts, and the support rod can drive the pot cover to rotate downward and downward, and align the pot body.

[0072] In addition, when the two protruding parts are in the vertical parts of the two tracks and the screw rod rotates in a direction m, the support rod can only move vertically downward due to the restriction of the two vertical parts, and can drive the pot cover to cover the pot body.

[0073] Furthermore, the ball bearing in the bearing seat rolls in the inclined part, which can reduce the friction of the inclined part and make the downward rotation more smooth.

[0074] Therefore, an electric rice cooker cover opening method and an electric rice cooker cover closing method are obtained, which can first only rise and then rotate upward, or first rotate downward and then only descend, and the opening and closing methods can avoid the influence of the inner container and the sealing element on the rotation operation mode, so that the opening or closing of the pot cover can be automatically completed.

[0075] The electric rice cooker cover opening and closing method of the present application adopts a track containing a vertical part and an inclined part, uses a screw rod to drive a support rod to move through a nut, and makes the protruding part determine its movement mode according to the different parts of the track it is in, that is, only rising or only descending, or rotating upward or rotating downward, which is suitable for the automatic opening or closing of the pot cover, and provides a new use mode for the electric rice cooker cover.

[0076] The electric rice cooker cover opening and closing method of the present application makes the protruding part determine its vertical movement and inclined movement according to the vertical part and the inclined part of the track it is in, and only one motor is used to realize the operation of the two movement modes, so that the method has the characteristics of simple control and low cost.

[0077] The electric rice cooker cover opening and closing method of the present application uses the track of the support rod formed by the upper and lower shells to realize the vertical and inclined movement of the support rod, so that the method steps are more compact and simplified, which not only facilitates the mold making and assembly, but also has better firmness and can better prevent the disconnection of the parts during use.

[0078] In addition, the electric rice cooker cover opening and closing method of the present application, when opening, the support rod first only rises, and then rotates and rises. In the rising stage, the sealing element of the cover can be driven by the support rod to separate from the inner container, and the inner container and the sealing element are avoided to affect the subsequent rotation and rising; in the rotation and rising stage, the cover no longer blocks the pot body and exposes the inner container for use.

[0079] Furthermore, the electric rice cooker cover opening and closing method of the present application, when closing, the support rod first rotates and descends, and then only descends. In the rotation and descent stage, the cover can be aligned with the pot body by the support rod and the influence of the inner container and the sealing element on the rotation is avoided; in the descent stage, the sealing element of the cover can be aligned with the inner container by the support rod and the sealing is pressed. BRIEF DESCRIPTION OF DRAWINGS

[0080] Figure 1 is a schematic diagram of the structure of the electric rice cooker using the present application;

[0081] Figure 2 is Figure 1 a schematic diagram of the electric rice cooker cover only lifted;

[0082] Figure 3 is Figure 1 a schematic diagram of the electric rice cooker cover opened;

[0083] Figure 4 is Figure 1 a schematic diagram of the working state of the driving mechanism of the electric rice cooker using the specific implementation method;

[0084] Figure 5 is Figure 4 a schematic diagram of the disassembly of the components of the driving mechanism;

[0085] Figure 6 is Figure 4 a schematic diagram of the driving mechanism in the closed state. DETAILED DESCRIPTION

[0086] The specific implementation structure using the method of the present application will be described in detail below with reference to the accompanying drawings:

[0087] Referring to Figure 4 — Figure 6The driving mechanism is driven by the reduction motor 11 through the shaft coupling 9 to rotate the screw rod 8, the nut 5 is installed at the concentric circle of the support rod 3, the screw rod 8 rotates to drive the support rod 3 to move through the nut 5, and the support rod 3 is installed in the upper cylindrical shell 6 and the lower cylindrical shell 7, and the support rod 3 extends out of the upper hole of the upper shell 6, and the left and right sides of the support rod 3 form a protruding part 3a; the lower shell 7 forms two lower tracks on the side wall upward, the lower track includes a recessed part 71 and an upper convex part 72, the recessed part 71 is adjacent to the upper convex part 72, the left side surface 71a of the recessed part 71 is constructed as a part of the left side of the vertical part of the track as a first left side, the bottom 71b of the recessed part 71 is constructed as the bottom of the vertical part of the track, the left side surface 72a of the upper convex part 72 is constructed as the right side of the vertical part of the track, the top surface 72b of the upper convex part 72 is constructed as the lower edge of the inclined part of the track, and the right side surface 72c of the upper convex part 72 is constructed as an adjacent surface; the inner side wall of the upper shell 6 forms two upper tracks, the upper track is a downward recess, the left side surface 6a of the recess is constructed as a part of the left side of the vertical part of the track as a second left side, the right side surface 6b of the recess is constructed as an abutting surface of the abutting surface, and the bottom 6c of the recess is constructed as the upper edge of the inclined part of the track; the lower shell 7 is inserted into the upper shell 6 through the upper convex part 72 to realize the cooperation of the two, wherein the first left side and the second left side form the left side of the vertical part of the track together, and the abutting surface of the upper shell 6 abuts at the abutting surface of the lower shell 7; in addition, the upper shell can be separated from the upper cover, that is, the upper cover 1 is arranged above the upper shell 6, the linear bearing 2 is installed on the support rod 3, the upper cover 1 covers the linear bearing 2, and the upper cover 1 is fixed with the upper shell 6, and the support rod 3 extends out of the middle hole of the upper cover 1; furthermore, the protruding part 3a is made into a bearing seat, and the ball bearing 4 is installed in the bearing seat, and the ball bearing 4 rolls in the inclined part to reduce the friction in the movement. In this way, a pair of tracks is formed by the two lower tracks and the two upper tracks respectively, the two tracks are distributed on the left and right sides of the shell, and the tracks are vertical at the lower part and present an inclined part extending in the right upper direction at the upper part, and the two bearing seats 3a and the ball bearing 4 of the support rod 3 can be installed in the vertical part of the two tracks in the upper and lower shells respectively.

[0088] It should be noted that the upper shell 6 and the lower shell 7 are both cylindrical, so the recessed part, the upper convex part and the recess are all arc-shaped, and the arc-shaped inclined part can better cooperate with the cylindrical support rod, so that the protruding part can always remain in the arc-shaped inclined part and not protrude out of the inclined part.

[0089] Referring to Figure 1 - Figure 3 The driving mechanism is installed inside the pot body B (not shown in the figure), the pot cover A is fixed with the support rod 3 and can move with the support rod 3, has only the functions of rising or descending, rotating and rising or rotating and descending, etc., to realize the automatic opening or closing of the pot cover A.

[0090] The specific implementation method of the electric rice cooker cover opening is as follows:

[0091] (10) The screw rod 8 is driven to rotate in the nut 5 by the reduction motor 11 through the shaft coupling 9;

[0092] (20) The nut 5 is fixed at the concentric circle of the support rod 3, so that the support rod 3 moves with the nut 5;

[0093] (30) The support rod 3 is located in a pair of rails containing vertical and inclined parts at different positions of the pair of protruding parts 3a;

[0094] (40) When the screw rod 8 rotates in a certain direction r, the protruding part 3a can only rise when it is in the vertical part, and the protruding part 3a can rotate and rise when it is in the inclined part.

[0095] (50) The electric rice cooker cover A is moved by the support rod 3, so that the cover A is away from the pot body B, and the inner container D is exposed.

[0096] Preferably, the above electric rice cooker cover opening method further comprises the following step: between step (30) and step (40), a step (35) is added;

[0097] (35) The upper shell 6 and the lower shell 7 are used to assemble the parts therein, and the support rod 3 extends from the top of the upper shell 6; and

[0098] In the lower shell 7, two downward rails are formed on the left and right sides;

[0099] In the upper shell 6, two upward rails are formed on the left and right sides;

[0100] The upper shell and the lower shell cooperate to form the pair of rails by the two upward rails and the two downward rails.

[0101] More preferably, in the above electric rice cooker cover opening method, the upward and downward rails and the bearing seat of step (35) are as follows:

[0102] The upward rail is a downward groove;

[0103] The downward rail comprises a recessed part 71 and an upward convex part 72, and the recessed part 71 is adjacent to the upward convex part 72;

[0104] The groove and the recessed part and the upward convex part form the rails:

[0105] The left side of the recessed part 71a is constructed as the left side of the vertical part of the rail, serving as the first left side;

[0106] The bottom of the recessed part 71b is constructed as the bottom of the vertical part of the rail;

[0107] the right side of the vertical portion of the track is formed by the left side surface 72a of the upper convex portion;

[0108] the lower edge of the inclined portion of the track is formed by the top surface 72b of the upper convex portion;

[0109] the abutment surface is formed by the right side surface 72c of the upper convex portion;

[0110] the left side edge of the vertical portion of the track is formed by the left side surface 6a of the groove as the second left side edge;

[0111] the abutment surface is formed by the right side surface 6b of the groove;

[0112] the upper edge of the inclined portion of the track is formed by the groove bottom 6c;

[0113] the lower shell 7 is inserted into the upper shell 6 with its upper convex portion to fit, wherein the first left side edge together with the second left side edge forms the left side edge of the vertical portion of the track;

[0114] the protruding portion 3a is made into a bearing seat and the ball bearing 4 is assembled in the bearing seat.

[0115] The specific implementation method of the electric rice cooker cover closing is as follows:

[0116] An electric rice cooker cover closing method, characterized in that, comprising the following steps:

[0117] (10), using a speed reducer motor 11 to drive the screw rod 8 to rotate in the nut 5 through the shaft coupling 9;

[0118] (20), fixing the nut 5 at the concentric circle of the support rod 3, and allowing the support rod 3 to move with the nut 5;

[0119] (30), the protruding portion 3a of the support rod 3 is located in a pair of tracks containing a vertical portion and an inclined portion;

[0120] (40), when the screw rod 8 rotates in a certain direction m, the protruding portion 3a can rotate and descend when it is in the inclined portion, and the protruding portion 3a can only descend when it is in the vertical portion;

[0121] (50), moving the electric rice cooker cover by the support rod 3, so that the cover A covers the pot body B, and the inner container D is closed.

[0122] Preferably, the above-mentioned scheme further comprises the following steps: between step (30) and step (40), a step (35) is added;

[0123] (35), assembling the components in the upper shell 6 and the lower shell 7, and the support rod 3 extends from the top of the upper shell 6; and

[0124] In the lower shell 7, two lower rails are formed upwardly and distributed left and right;

[0125] In the upper shell 6, two upper rails are formed inwardly and distributed left and right;

[0126] The upper shell and the lower shell are matched, and the two upper rails and the two lower rails form the pair of rails.

[0127] Preferably, in the above-mentioned electric rice cooker cover closing method, the upper and lower rails and the protruding part in step (35) are:

[0128] The upper rail is a downward groove;

[0129] The lower rail comprises a recessed part 71 and an upper convex part 72, and the recessed part 71 is adjacent to the upper convex part 72;

[0130] The groove and the recessed part and the upper convex part form the rail:

[0131] The left side of the recessed part 71a forms a part of the left side of the vertical part of the rail as a first left side;

[0132] The bottom of the recessed part 71b forms the bottom of the vertical part of the rail;

[0133] The left side of the upper convex part 71a forms the right side of the vertical part of the rail;

[0134] The top of the upper convex part 72b forms the lower edge of the inclined part of the rail;

[0135] The right side of the upper convex part 72c forms an abutting surface;

[0136] The left side of the groove 6a forms a part of the left side of the vertical part of the rail as a second left side;

[0137] The right side of the groove 6b forms an abutting surface abutting the abutting surface;

[0138] The groove bottom 6c forms the upper edge of the inclined part of the rail;

[0139] The lower shell 7 is inserted into the upper shell 6 by the upper convex part, and the first left side and the second left side form the left side of the vertical part of the rail together;

[0140] The protruding part 3a is made into a bearing seat, and the ball bearing 4 is assembled in the bearing seat.

[0141] As can be seen from the embodiment, the opening method and the closing method have common steps, which can be completed by the same structure, and therefore, the method of the application is also beneficial to further simplify the driving structure.

Claims

1. A method for opening a rice cooker lid, comprising the following steps: (10) A motor is used to drive the screw to rotate in the nut; (20) Fix the nut on the concentric circle of the support rod and let the support rod move with the nut; (30) A pair of protruding parts of a support rod are respectively located in a pair of rails having a vertical portion and a slope portion, wherein: The slope portion is above the vertical portion; (35) The upper and lower shells are used to assemble the components therein, and the support rod can extend from the top of the upper shell; On the lower shell, two lower tracks are formed upwards and distributed left and right; Two upper rails are formed on the inner side of the upper shell and are distributed on the left and right sides; The upper and lower tracks adopt the following structures: The upper track is a downward groove; The lower track includes a concave portion and a convex portion, wherein the concave portion is adjacent to the convex portion; The groove, the concave portion and the convex portion form the track: A portion of the left edge of the vertical portion of the track is constructed from the left side surface of the recessed portion, serving as a first left edge; The bottom of the vertical part of the track is constructed by the bottom of the concave part; The left side of the convex part is constructed as the right edge of the vertical part of the track; The top surface of the convex part is constructed as the lower edge of the track slope part; The right side of the convex part is constructed as the adjacent surface; A portion of the left edge of the vertical portion of the track is constructed from the left side of the groove and serves as a second left edge; The right side of the groove is constructed as an abutment surface that abuts the adjacent surface, The bottom of the groove is constructed as the upper edge of the track slope; The lower shell is inserted into the upper shell with its upper convex portion to fit together, wherein the first left edge and the second left edge together form the left edge of the vertical portion of the track; The upper shell and the lower shell are matched, and the two upper rails and the two lower rails respectively form the two walking tracks; (40) When the screw is rotated in a certain direction r, the protruding part can only rise when it is in the vertical part, and can rotate and rise when it is in the slope part; (50) The support rod drives the pot cover to move so that the pot cover leaves the pot body.

2. The method for opening the rice cooker lid according to claim 1, wherein: The motor adopts a reduction motor, and the motor drives the screw to rotate through a coupling.

3. The method for opening the rice cooker lid according to claim 1 or 2, wherein: The protruding portion is made into a bearing seat and a ball bearing is assembled in the bearing seat.

4. A method for closing a rice cooker lid, characterized in that: The following steps are involved: (10) A motor is used to drive the screw to rotate in the nut; (20) Fix the nut on the concentric circle of the support rod and let the support rod move with the nut; (30) A pair of protruding parts of the support rod are respectively located in a pair of rails having a vertical portion and a slope portion, wherein the slope portion is located above the vertical portion; (35) The components are assembled in an upper and lower shell, and the support rod can extend from the top of the upper shell; and On the lower shell, two lower tracks are formed upwards and distributed left and right; Two upper rails are formed on the inner side of the upper shell and are distributed on the left and right sides; The upper and lower tracks adopt the following structures: The upper track is a downward groove; The lower track includes a concave portion and a convex portion, wherein the concave portion is adjacent to the convex portion; The groove, the concave portion and the convex portion form the track: A portion of the left edge of the vertical portion of the track is constructed from the left side surface of the recessed portion, serving as a first left edge; The bottom of the vertical part of the track is constructed by the bottom of the concave part; The left side of the convex part is constructed as the right edge of the vertical part of the track; The top surface of the convex part is constructed as the lower edge of the track slope part; The right side of the convex part is constructed as the adjacent surface; A portion of the left edge of the vertical portion of the track is constructed from the left side of the groove and serves as a second left edge; An abutment surface constructed by the right side of the groove to abut the adjacent surface; The bottom of the groove is constructed as the upper edge of the track slope; The lower shell is inserted into the upper shell with its upper convex portion to achieve the cooperation between the two, wherein the first left edge and the second left edge together form the left edge of the vertical portion of the track; The upper shell and the lower shell are matched, and the two upper rails and the two lower rails respectively form the two walking tracks; (40) When the screw is rotated in a certain direction m, the protruding part can rotate and descend when it is in the slope part, while the protruding part can only descend when it is in the vertical part; (50) The support rod drives the pot cover to move so that the pot cover covers the pot body.

5. The method for closing the rice cooker lid according to claim 4, wherein: The motor adopts a reduction motor, and the motor drives the screw to rotate through a coupling.

6. The method for closing the rice cooker lid according to claim 4 or 5, wherein: The protruding portion is made into a bearing seat and a ball bearing is assembled in the bearing seat.

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