Automobile wheel hub capable of reducing wind resistance

Abstract

The present invention discloses a car wheel hub that can reduce wind resistance, and relates to the technical field of car wheel hubs. The wheel hub body includes a wheel rim, a wheel disc, and a wheel spoke. A closure member is provided inside the wheel rim, and the closure member is provided on the outside of the wheel disc. The closure member is used to seal the cavity of the wheel rim to reduce its wind resistance during driving. The closure member includes an outer plate and an inner plate, and the outer plate is fixed to the outside of the wheel spoke. The present invention is aimed at improving the problem that the cavity of the car wheel hub in the prior art is generally open, but the open wheel hub cavity will be impacted by airflow when the vehicle is driving at high speed, and the internal cavity will form vortices or turbulence, which will increase aerodynamic resistance and energy consumption. The present invention has the advantages of providing a closure member that can be opened and closed on the surface of the wheel hub, so that when driving at high speed, the closure member can seal the cavity to reduce aerodynamic resistance, and when braking, the closure member can be opened to improve heat dissipation.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile hubs, and in particular to an automobile hub capable of reducing wind resistance. Background Art

[0002] The automobile wheel hub is a cylindrical metal component inside the automobile tire that is centered on the axle and is used to support the tire. It is an important component that connects the brake drum, wheel disc and half-axle.

[0003] In the existing technology, in order to make the wheel hub lightweight, a cavity is generally provided inside the wheel hub. The cavity structure increases the contact area between the wheel hub and the air, which is conducive to the rapid dissipation of heat from the brake disc through heat conduction, avoiding safety hazards caused by brake heat accumulation. However, the wheel hub cavity will be impacted by airflow when the vehicle is traveling at high speed, and the internal cavity will form eddies or turbulence, increasing aerodynamic resistance and energy consumption.

[0004] In response to the above technical problems, the present invention discloses an automobile wheel hub that can reduce wind resistance. The present invention has the advantages of providing an openable and closable closure member on the surface of the wheel hub, so that when driving at high speed, the closure member can seal the cavity to reduce aerodynamic resistance, and when braking, the closure member can be opened to improve heat dissipation. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the existing technology and provide an automobile wheel hub that can reduce wind resistance, so as to solve the technical problems that the cavity of the automobile wheel hub in the existing technology is generally open, but the open wheel hub cavity will be impacted by the airflow when the vehicle is running at high speed, and the internal cavity will form vortices or turbulence, increasing aerodynamic resistance and increasing energy consumption. The present invention has the advantages of providing a closure member that can be opened and closed on the surface of the wheel hub, so that when running at high speed, the closure member can seal the cavity to reduce aerodynamic resistance, and when braking, the closure member can be opened to improve heat dissipation.

[0006] The present invention is achieved through the following technical solutions: The present invention discloses a car wheel hub capable of reducing wind resistance, comprising a wheel hub body, wherein the wheel hub body comprises a wheel rim, a wheel disc and a wheel spoke; a sealing member is provided inside the wheel rim, and the sealing member is provided outside the wheel disc, and is used to seal the cavity of the wheel rim to reduce the wind resistance of the vehicle during driving;

[0007] The closure member includes an outer plate and an inner plate, wherein the outer plate is fixed to the outer side of the spoke, and the inner plate is rotatably disposed between the outer plate and the spoke and is coaxially arranged with the outer plate;

[0008] The outer plate and the inner plate are both provided with ventilation slots distributed in a ring array. The inner plate can rotate around the axis to achieve aligned opening and offset closing of the ventilation slots. The rotation of the inner plate is driven by a driving assembly.

[0009] Furthermore, a central axis is fixedly provided on the outer side of the wheel disc and the wheels are concentrically arranged with each other. The outer plate is fixedly sleeved on the outside of the central axis, and the outer circumferential outer wall of the outer plate is fitted and sealed with the inner wall of the rim. The inner plate is located between the outer plate and the spokes, and the inner plate is rotatably sleeved on the outside of the central axis, and the outer circumferential outer wall of the inner plate is rotatably sealed with the inner wall of the rim. The outer plate and the inner plate are fitted with each other on the facing sides.

[0010] Furthermore, the drive assembly includes an electric push rod, a temperature sensor and a controller. The electric push rod is installed on the inner wall of the wheel rim, and the telescopic axis of the electric push rod is perpendicular to the inner plate. The electric push rod drives the inner plate to rotate through a transmission member. A temperature sensor is installed on the inner side of the spoke for monitoring the temperature of the brake disc. The controller turns on the electric push rod and controls the extension time of its telescopic axis based on the temperature data monitored by the temperature sensor.

[0011] Furthermore, the transmission part includes a gear, a gear ring, a rotating shaft and a conversion part. The internal rotation of the spoke is provided with a rotating shaft. One end of the rotating shaft extends between the inner plate and the spoke, and a gear is fixedly sleeved on this end. The inner side surface of the inner plate is fixedly provided with a gear ring, and the gear is meshed with the gear ring. A conversion part is provided between the telescopic shaft of the electric push rod and the rotating shaft, and the conversion part is used to convert the linear motion of the telescopic shaft of the electric push rod into the circular rotation of the rotating shaft.

[0012] Furthermore, the conversion part includes a spiral rod and a spiral groove, the spiral rod is fixedly arranged at one end of the telescopic shaft of the electric push rod, the spiral groove is opened inside the rotating shaft, and the spiral rod is inserted into the spiral groove.

[0013] Furthermore, a plurality of the temperature sensors are distributed along the circumference of the brake disc on the inner side of the spoke, and the temperature sensors are configured as non-contact sensors.

[0014] Furthermore, a gap is provided between the inner plate and the spokes, and the gear ring is provided on the side wall of the inner plate at a position close to the outer circumferential edge.

[0015] The present invention has the following advantages:

[0016] The present invention provides a closing piece, and the closing piece is provided with a ventilation slot. The ventilation slot on the closing piece has an opening and closing function, and the wheel rim cavity can be closed by the closing piece, so that the wheel hub body is a closed wheel hub, avoiding the generation of large aerodynamic resistance and increased vehicle energy consumption when driving at high speed. In addition, the opening and closing of the closing piece is controlled by the driving component, and the opening and closing adjustment of the ventilation slot is set to the temperature of the brake disc as a trigger mechanism, so that the ventilation slot can be opened in time to ventilate and dissipate heat to the brake disc. In addition, a controller and a temperature sensor are provided to form a closed-loop control system with the electric push rod, and the extension state and duration of the electric push rod are determined according to the temperature data. When the brake disc is high in temperature, the opening time of the electric push rod is extended, and when it is low in temperature, the opening time of the electric push rod is shortened, so that the heat dissipation effect is better and the energy consumption is further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0018] Figure 2 It is a schematic diagram of the wheel rim structure of the present invention;

[0019] Figure 3 This is a schematic structural diagram of the closure member of the present invention in a closed state;

[0020] Figure 4 It is a schematic diagram of the cross-sectional structure of the wheel rim of the present invention;

[0021] Figure 5 is a schematic cross-sectional structural diagram of a closure member of the present invention;

[0022] Figure 6 For the present invention Figure 4 A local enlarged structural diagram of point A;

[0023] Figure 7 For the present invention Figure 5 Schematic diagram of the local enlarged structure at point B.

[0024] In the figure: 1. Hub body; 2. Closing part; 3. Ventilation groove; 4. Clearance hole; 5. Sealing ring; 6. Drive assembly; 7. Transmission part; 101. Rim; 102. Disc; 103. Spoke; 201. Center shaft; 202. Outer plate; 203. Inner plate; 601. Electric push rod; 602. Controller; 603. Temperature sensor; 701. Gear; 702. Gear ring; 703. Rotating shaft; 704. Converter; 741. Screw rod; 742. Spiral groove. DETAILED DESCRIPTION

[0025] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented based on the technical solution of the present invention, and a detailed implementation method and specific operation process are given. However, the scope of protection of the present invention is not limited to the following embodiment. In the description of the present invention, words indicating directions or positional relationships such as "front", "rear", "left", and "right" are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, it should not be understood as a limitation on the present invention.

[0026] The embodiment discloses a car wheel hub that can reduce wind resistance, such as Figure 1-Figure 7 As shown, it includes a hub body 1, as shown Figure 2 As shown, the hub body 1 specifically includes a rim 101 that directly cooperates with the tire and a cavity inside the rim 101. It also includes a wheel disc 102. The wheel disc 102 serves as the part connecting the wheel hub to the axle and has multiple bolt holes distributed around the periphery, and is then fixed to the axle by bolts. Spokes 103 are also provided between the wheel disc 102 and the wheel rim 101. The spokes 103 are configured as spokes extending radially from the center of the wheel rim 101 to the edge of the wheel rim 101. Their main function is to connect the wheel rim 101 and the wheel disc 102 and transmit torque to the axle.

[0027] In the prior art, there is space between the spokes of the wheel 103, so that the cavity of the wheel rim 101 is connected with the outside, and air can flow in the internal cavity of the wheel rim 101, which is beneficial to the heat dissipation of the brake disc. However, when the cavity of the wheel rim 101 is connected with the outside, there will be a cavity that is impacted by the airflow when the vehicle is traveling at high speed, and the internal cavity will form eddies or turbulence, increasing aerodynamic resistance and thus increasing energy consumption.

[0028] Therefore, in this embodiment, Figure 1 and Figure 3 As shown, a closing member 2 is provided inside the wheel rim 101. The closing member 2 is specifically provided on the side opposite to the side where the wheel disc 102 is connected to the axle, that is, on the outside of the wheel spoke 103. The wheel rim 101 is then sealed by the closing member 2, making the hub body 1 a closed hub, thereby avoiding the generation of large aerodynamic drag and increased vehicle energy consumption when driving at high speeds.

[0029] When the sealing member 2 seals the cavity of the hub body 1, it will be detrimental to the heat dissipation of the brake disc, which will cause the brake disc to overheat and be damaged, shortening its service life.

[0030] In this embodiment, ventilation slots 3 are provided on the closing member 2, and the ventilation slots 3 are configured to have two modes of opening and closing, and the opening and closing of the ventilation slots 3 are configured to be triggered according to the brake disc temperature, so that each time the brake disc temperature reaches a set value, the ventilation slots 3 are opened for heat dissipation, and during normal driving, the ventilation slots 3 are closed to reduce wind resistance.

[0031] In this embodiment, the set value temperature is set to 400°, but in actual use, it can be adjusted by ±30° depending on factors such as materials and environment.

[0032] Specifically, such as Figures 1-4 As shown, the closure member 2 includes a central shaft 201, an outer plate 202 and an inner plate 203, wherein the central shaft 201 is fixedly connected to the center of the wheel disc 102 and is concentrically arranged with each other, and the inner plate 203 is rotatably sleeved on the outside of the central shaft 201, and the outer circumferential outer wall of the inner plate 203 is arranged to fit and slide with the inner wall of the rim 101, and the outer side of the inner plate 203, that is, the side of the inner plate 203 opposite to the spoke 103 is provided with the outer plate 202, and the outer plate 202 is fixedly sleeved on the outside of the central shaft 201, and the outer circumferential outer wall of the outer plate 202 is also fitted and sealed with the inner wall of the rim 101, and the outer plate 202 and the inner plate 203 face each other and slide with each other, and the interior of the outer plate 202 and the interior of the inner plate 203 are both provided with ventilation slots 3;

[0033] The ventilation slots 3 on the outer plate 202 pass through both side end surfaces of the outer plate 202, and the ventilation slots 3 on the inner plate 203 also pass through both side end surfaces of the inner plate 203. The ventilation slots 3 are arranged in a fan shape, and a plurality of fan-shaped ventilation slots 3 are respectively provided on the outer plate 202 and the inner plate 203. The fan-shaped ventilation slots 3 are arranged in a circular array with the central axis 201 as the center. When the inner plate 203 is rotated, the ventilation slots 3 on the inner plate 203 are rotated to between two adjacent ventilation slots 3 of the outer plate 202, so that the ventilation slots 3 on the inner plate 203 can be covered by the outer plate 202, and the ventilation slots 3 on the outer plate 202 can be covered by the inner plate 203, thereby realizing the closure of the ventilation slots 3;

[0034] In other words, when the ventilation grooves 3 on the outer plate 202 and the inner plate 203 are aligned with each other, the ventilation grooves 3 are opened so that the inner cavity of the rim 101 is connected with the outside, and when the ventilation grooves 3 on the outer plate 202 and the inner plate 203 are staggered with each other, the ventilation grooves 3 are closed, thereby blocking the connection between the inner cavity of the rim 101 and the outside.

[0035] Therefore, when it is necessary to open the ventilation slots 3 of the closure 2, it is only necessary to rotate the inner plate 203 so that after the inner plate 203 is rotated by an angle, the ventilation slots 3 on the outer plate 202 and the inner plate 203 are aligned with each other, and then the ventilation slots 3 are opened for ventilation and heat dissipation. When it is necessary to close the ventilation slots 3 of the closure 2, the inner plate 203 is reset and rotated so that the ventilation slots 3 on the outer plate 202 and the inner plate 203 are staggered with each other, and then cover each other's ventilation slots 3, so that the ventilation slots 3 are closed.

[0036] It should be noted that the rotational connection between the inner plate 203 and the central shaft 201 is configured as a rotational seal. A sealing ring 5 is provided on the outer circumferential wall of the inner plate 203, so that the inner plate 203 and the inner wall of the rim 101 can be rotationally connected while ensuring sealing. The outer circumferential wall of the outer plate 202 and the inner wall of the rim are sealed by providing a sealing ring 5. In addition, a sealing layer can also be provided on the facing side of the outer plate 202 and the inner plate 203 to achieve sealing between the outer plate 202 and the inner plate 203.

[0037] The material of the closing member 2 can be a high temperature resistant material, such as 304 stainless steel or other metal materials. In addition, a clearance hole 4 is opened at the center of the outer plate 202 and the inner plate 203 to make way for the bolt hole.

[0038] The rotation of the inner plate 203 is configured to be controlled by a drive assembly 6, and the drive assembly 6 is configured to be a component driven by electricity. In this embodiment, the drive assembly 6 is configured to include an electric push rod 601, a controller 602 and a temperature sensor 603. The rotation of the inner plate 203 is achieved by the extension and retraction of the electric push rod 601. In addition, in order to achieve timely heat dissipation of the brake disc when the brake disc is hot, a temperature sensor 603 is provided to measure the temperature of the brake disc. When the temperature of the brake disc reaches a set value, the electric push rod 601 can be started to rotate the inner plate 203, thereby controlling the ventilation slot 3 to open for ventilation and heat dissipation. When the brake disc is below the set temperature, the ventilation slot 3 can remain closed, thereby reducing wind resistance and energy consumption.

[0039] Taking into account that the length of braking time and the braking force have a significant impact on the temperature of the brake disc, in this embodiment, the temperature of the brake disc is used as a trigger mechanism for ventilation, so that the temperature of the brake disc can be understood more accurately, and then the opening time of the ventilation slot 3 can be adjusted in real time according to the temperature of the brake disc, so that the opening time of the ventilation slot 3 is more adaptable, the heat dissipation effect is better, and energy consumption is further reduced.

[0040] It should be noted that there is a gap between the inner plate 203 and the spokes 103 .

[0041] Specifically, in order to realize the rotation control of the inner plate 203 by the electric push rod 601, as shown in FIG. Figure 4-Figure 7 As shown, the electric push rod 601 controls the rotation of the inner plate 203 by setting a transmission member 7. The transmission member 7 in this embodiment is configured to transmit the power through a gear 701.

[0042] Transmission member 7 gear 701, gear ring 702, shaft 703 and conversion part 704, wherein a shaft 703 is rotatably provided inside a spoke at a spoke 103, and specifically a hole is opened inside the spoke and passes through the end faces of both sides of the spoke, and the shaft 703 is rotatably provided inside the hole through a rotating connection member such as a bearing, and the two ends of the shaft 703 extend to both sides of the spoke 103 respectively, one end of the shaft 703 is between the inner plate 203 and the spoke 103, and the other end is inside the cavity of the rim 101, and the shaft 703 is located between the inner plate 203 and the spoke A gear 701 is fixedly sleeved on one end between the spokes 103, and a gear ring 702 is fixedly provided on the side of the inner plate 203 facing the spokes 103, that is, the inner side surface of the inner plate 203, and the gear ring 702 is provided in a section, and the gear 701 is meshed with the gear ring 702. It should be noted that the gear ring 702 is provided at a position close to the outer circumferential edge of the inner plate 203, so that the gear 701 can be rotated by rotating the rotating shaft 703, and then the inner plate 203 is rotated by the meshing of the gear 701 and the gear ring 702, thereby opening or closing the ventilation slot 3;

[0043] In addition, the electric push rod 601 is fixedly installed inside the rim 101, and the telescopic axis of the electric push rod 601 is perpendicular to the spoke 103 and extends toward the spoke 103, and the telescopic axis of the electric push rod 601 is concentrically arranged with the rotating shaft 703. A conversion part 704 is provided between the telescopic axis of the electric push rod 601 and the rotating shaft 703. The conversion part 704 is used to convert the linear motion of the telescopic axis of the electric push rod 601 into the circular rotation of the rotating shaft 703.

[0044] like Figure 6 As shown, the conversion part 704 includes a spiral rod 741 and a spiral groove 742, wherein the spiral rod 741 is fixedly arranged at one end of the telescopic shaft, and a spiral groove 742 is opened inside the rotating shaft 703, and the spiral groove 742 passes through the end surface of the rotating shaft 703 facing the electric push rod 601, the spiral rod 741 is plugged into the spiral groove 742, and the rotating shaft 703 is rotated by the linear motion of the spiral rod 741 inside the spiral groove 742.

[0045] Through the above-mentioned arrangement, when it is necessary to control the rotation of the inner plate 203, it is only necessary to control the extension of the telescopic shaft of the electric push rod 601. The extension of the telescopic shaft causes the spiral rod 741 to be inserted into the spiral groove 742, causing the rotating shaft 703 to rotate. The rotating shaft 703 will drive the gear 701 to rotate and rotate the inner plate 203 through engagement with the gear ring 702, thereby controlling the opening of the ventilation slot 3. When closing, the telescopic shaft of the electric push rod 601 contracts, causing the inner plate 203 to reset and rotate, thereby closing the ventilation slot 3.

[0046] In addition, if Figure 4 As shown, the temperature sensor 603 is configured as a non-contact temperature sensor 603, specifically a laser temperature sensor 603, and the temperature sensor 603 is installed on the inner side of the spoke 103. The temperature of the brake disc is monitored by the temperature sensor 603. It should be noted that there are multiple temperature sensors 603, and the multiple temperature sensors 603 are distributed circumferentially along the brake disc, thereby performing multi-point temperature monitoring on the brake disc, thereby improving the accuracy of temperature monitoring.

[0047] In this embodiment, a controller 602 is also provided. The controller 602 can be installed on the inner side of the hub body 1 or inside the engine compartment. In terms of control logic, the temperature sensor 603, the controller 602, and the electric push rod 601 form a closed-loop control system. The controller 602 determines the extension and retraction state and duration of the electric push rod 601 based on the temperature data monitored by the temperature sensor 603. Specifically, the opening time of the electric push rod 601 is extended when the brake disc is at a high temperature, and the opening time of the electric push rod 601 is shortened when the temperature is low.

[0048] It should be noted that, in this embodiment, the electric push rod 601, the temperature sensor 603 and the controller 602 are connected via a wireless module.

[0049] The principle of the present invention is as follows: Under normal conditions, the closure 2 is in a closed state, so that when the vehicle is driving, the ventilation slot 3 can be closed to reduce wind resistance and energy consumption. At the same time, the temperature sensor 603 monitors the temperature of the brake disc in real time. Once the brake is applied, the temperature of the brake disc rises to the set value, the electric push rod 601 is started, and the telescopic shaft of the electric push rod 601 is extended. The extension of the telescopic shaft allows the spiral rod 741 to be inserted into the spiral groove 742, causing the rotating shaft 703 to rotate. The rotating shaft 703 will drive the gear 701 to rotate and rotate the inner plate 203 through engagement with the gear ring 702, thereby controlling the opening of the ventilation slot 3 to ventilate and dissipate heat for the brake disc. At the same time, the controller 602 determines the telescopic state and duration of the electric push rod 601 according to the temperature data. When the brake disc is at a high temperature, the opening time of the electric push rod 601 is extended, and when it is at a low temperature, the opening time of the electric push rod 601 is shortened.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A car wheel hub capable of reducing wind resistance, comprising a wheel hub body (1), wherein the wheel hub body (1) comprises a wheel rim (101), a wheel disc (102) and a wheel spoke (103), characterized in that: A closing member (2) is provided inside the wheel rim (101), and the closing member (2) is provided outside the wheel disc (102). The closing member (2) is used to close the cavity of the wheel rim (101) to reduce the wind resistance during driving. The closure member (2) comprises an outer plate (202) and an inner plate (203), wherein the outer plate (202) is fixed to the outer side of the spoke (103), and the inner plate (203) is rotatably disposed between the outer plate (202) and the spoke (103) and is coaxially arranged with the outer plate (202); The outer plate (202) and the inner plate (203) are both provided with ventilation slots (3) distributed in an annular array, and the inner plate (203) can rotate around the axis to achieve aligned opening and dislocated closing of the ventilation slots (3), and the rotation of the inner plate (203) is driven by a driving assembly (6); The driving assembly (6) includes an electric push rod (601), a temperature sensor (603) and a controller (602), wherein the electric push rod (601) is mounted on the inner wall of the wheel rim (101), and the telescopic axis of the electric push rod (601) is perpendicular to the inner plate (203), and the electric push rod (601) drives the inner plate (203) to rotate through the transmission member (7), and a temperature sensor (603) is mounted on the inner side of the wheel spoke (103) for monitoring the temperature of the brake disc, and the controller (602) activates the electric push rod (601) and controls the extension time of the telescopic axis according to the temperature data monitored by the temperature sensor (603); The transmission member (7) includes a gear (701), a gear ring (702), a rotating shaft (703), and a conversion portion (704); the spoke (103) is provided with a rotating shaft (703) for internal rotation; one end of the rotating shaft (703) extends between the inner plate (203) and the spoke (103), and the gear (701) is fixedly sleeved on this end; the inner side surface of the inner plate (203) is fixedly provided with a gear ring (702); the gear (701) and the gear ring (702) are meshed; and a conversion portion (704) is provided between the telescopic shaft of the electric push rod (601) and the rotating shaft (703); The conversion part (704) is used to convert the linear motion of the telescopic shaft of the electric push rod (601) into the circular rotation of the rotating shaft (703). The conversion part (704) includes a spiral rod (741) and a spiral groove (742). The spiral rod (741) is fixedly arranged at one end of the telescopic shaft of the electric push rod (601). The spiral groove (742) is provided inside the rotating shaft (703). The spiral rod (741) is inserted into the spiral groove (742). A plurality of temperature sensors (603) are distributed along the circumference of the brake disc on the inner side of the spoke (103), and the temperature sensors (603) are configured as non-contact sensors.

2. The automobile wheel hub capable of reducing wind resistance according to claim 1, characterized in that: The outer side of the wheel disc (102) is fixedly provided with a central axis (201) and the wheels are concentrically arranged with each other. The outer plate (202) is fixedly sleeved on the outside of the central axis (201). The outer circumferential outer wall of the outer plate (202) is in contact with and sealed against the inner wall of the wheel rim (101). The inner plate (203) is located between the outer plate (202) and the spoke (103). The inner plate (203) is rotatably sleeved on the outside of the central axis (201). The outer circumferential outer wall of the inner plate (203) is in contact with and sealed against the inner wall of the wheel rim (101). The outer plate (202) and the inner plate (203) are in contact with each other on their facing sides.

3. The automobile wheel hub capable of reducing wind resistance according to claim 1, characterized in that: A spacing is provided between the inner plate (203) and the spoke (103), and the gear ring (702) is provided on the side wall of the inner plate (203) at a position close to the outer circumferential edge.

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