Clutch mechanism

Abstract

To provide a clutch mechanism having little dispersion of a load limit value.SOLUTION: A clutch mechanism C connected to a movable member and cutting off the transmission of an external force when a predetermined load or more is applied to the movable member includes a first member 21 having a projecting toothed portion 21T, a second member 22 having a recessed toothed portion 21T with which the projecting toothed portion 22T is engaged, and an urging member 23 for urging the projecting toothed portion 21T and the recessed toothed portion 22T in an engaging direction. The clutch mechanism C is configured such that the first member 21 and the second member 22 rotate relative to each other in a direction in which the engagement between the protruding teeth 21T and the recessed teeth 22T is released to interrupt the transmission of the load. In the clutch mechanism C, a load transmission path is constituted so as to make a load act from the pressing teeth flank 21T of the recessed teeth flank 21d to the pressure receiving teeth flank 22T of the projecting teeth flank 22d, and one of the pressure receiving teeth flank 21d and the pressing teeth flank 22d is provided with a projection 21d projecting toward the other of the pressure receiving teeth flank 22d and the pressing teeth flank 21e.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a clutch mechanism. [Background technology]

[0002] Patent Document 1 discloses a movable spoiler device provided at the front of a vehicle. The movable spoiler device is configured to be able to deploy and retract using the driving force of an actuator. A clutch mechanism is provided on the driving force transmission path between the actuator and the spoiler device.

[0003] The clutch mechanism disclosed in Patent Document 1 includes a first engaging member and a second engaging member having engaging surfaces with alternating succession of peaks and valleys, and a biasing member that engages the engaging surfaces of the first engaging member and the second engaging member. This allows the clutch mechanism to block the transmission of an external force when an unintended external force acts on the spoiler member. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-90278 Summary of the Invention [Problem to be solved by the invention]

[0005] The clutch mechanism described in Patent Document 1 enables the absorption of external forces acting on the spoiler member by blocking the transmission of the external forces when the spoiler member in the deployed state interferes with an obstacle.

[0006] Specifically, when an external force is applied, this clutch mechanism blocks the transmission of the external force by allowing the peak portion that engages with the valley portion to disengage from the valley portion, thereby allowing relative rotation between the first engaging member and the second engaging member.

[0007] In a clutch mechanism that blocks the action of an external force in this way, it is important to reliably block the external force when the external force (e.g., torque) exceeds a predetermined value (hereinafter referred to as the "load limit value"). The load limit value varies depending on the inclination angle of the contact surfaces between the peaks and valleys of the first and second engagement members, the biasing force that brings the peaks and valleys into contact, the surface roughness (surface roughness) of the contact surfaces between the peaks and valleys, and other factors. Therefore, in the clutch mechanism, the inclination angle of the contact surfaces between the peaks and valleys, the biasing force that brings the peaks and valleys into contact, the surface roughness of the contact surfaces between the peaks and valleys, and other factors are set to achieve the desired load limit value.

[0008] However, because the peaks and valleys of the first and second engaging members slide in contact with each other when external force is interrupted, repeated interruption of external force causes wear at the contact surfaces between the peaks and valleys, reducing the surface roughness and sliding resistance. Furthermore, the surface roughness of the contact surfaces between the peaks and valleys is affected by the conditions (such as mold temperature and material temperature) used when producing the first and second engaging members, and varies from one member to another.

[0009] In this way, the surface roughness of the contact surface between the peaks and valleys is easily affected by the operating conditions of the clutch mechanism and the production conditions of the parts. Therefore, if the surface roughness has a large effect on the load limit, the load limit of the clutch mechanism is likely to vary and become unstable.

[0010] For these reasons, there is a demand for a clutch mechanism with less variation in load limit values. [Means for solving the problem]

[0011] A characteristic configuration of a clutch mechanism according to the present invention is a clutch mechanism that is connected to a movable member and cuts off the transmission of an external force when a load equal to or greater than a predetermined value acts on the movable member, the clutch mechanism comprising: a first member having convex tooth portions; a second member having concave tooth portions with which the convex tooth portions engage; and a biasing member that biases at least one of the first member and the second member in a direction to cause the convex tooth portions to engage with the concave tooth portions; the clutch mechanism is configured such that as the load increases, the first member and the second member rotate relative to each other in a direction to release the engagement between the convex tooth portions and the concave tooth portions against the biasing force of the biasing member, thereby cutting off the transmission of the load; a load transmission path is configured such that the load acts from the pressing tooth surface of the concave tooth portion to the pressure-receiving tooth surface of the convex tooth portion; and one of the pressure-receiving tooth surface and the pressing tooth surface is provided with a protrusion that protrudes toward the other of the pressure-receiving tooth surface and the pressing tooth surface.

[0012] According to this configuration, when an excessive load is applied, the first and second members rotate relative to each other while the protrusions formed on either the pressure-receiving tooth surface of the convex tooth portion or the pressure-receiving tooth surface of the concave tooth portion abut against the other of the pressure-receiving tooth surface of the convex tooth portion or the pressure-receiving tooth surface of the concave tooth portion. This disengages the convex tooth portion from the concave tooth portion, thereby interrupting the transmission of the load. In this case, the protrusions wear, and the surface roughness (roughness) of the portions abutting the tooth surfaces changes. However, the portions of the protrusions abutting the other of the pressure-receiving tooth surface or the pressure-receiving tooth surface are small compared to the entire area of ​​the pressure-receiving tooth surface. In other words, according to this configuration, the contact area between the pressure-receiving tooth surface and the pressure-receiving tooth surface can be reduced, thereby reducing the influence of surface roughness on the load limit and suppressing variation in the load limit. This allows for the realization of a clutch mechanism with minimal variation in the load limit. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a vehicle body on which a drive unit including a clutch mechanism according to an embodiment of the present invention is mounted. [Figure 2] FIG. 1 is a perspective view showing a spoiler with a drive unit and hinge attached thereto. [Figure 3]FIG. 4 is a cross-sectional view showing the drive unit when the spoiler is in the retracted position. [Figure 4] FIG. 4 is a cross-sectional view showing the drive unit when the spoiler is in a protruding position. [Figure 5] FIG. 4 is a partial enlarged view showing a clutch mechanism attached to the drive unit. [Figure 6] FIG. 10 is a cross-sectional view showing a state in which the driving member and the driven member are engaged with each other. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of a clutch mechanism according to the present invention will be described with reference to the drawings. In this embodiment, as an example of a clutch mechanism, a clutch mechanism provided in a drive system of an electric active spoiler provided on the underside of the front body of a vehicle such as a passenger car will be described. Furthermore, the embodiments disclosed in this specification are merely examples, and the clutch mechanism according to the embodiment of the present invention is not limited thereto and can be modified as appropriate within the scope of the present invention.

[0015] [Basic configuration] As shown in Fig. 1, an electric spoiler 3 (an example of a movable member) is provided at the front of a vehicle body 1 of a passenger car, forward of the front wheels 2, below a front bumper 4 so as to be able to freely retract and retract. The spoiler 3 is supported so as to be able to switch between a stored position D and an extended position E by the driving force of a drive unit A (see Figs. 3 and 4). In the following description of this embodiment, the positions of the various parts of the spoiler 3 or the positional relationships of the various parts of the drive unit A will be described in accordance with the positional relationships in the front-rear, width, and up-down directions of the vehicle body 1.

[0016] The stored position D is a position where the spoiler 3 is stored above the lower surface of the front bumper 4, and the protruding position E is a position where the spoiler 3 protrudes below the lower surface of the front bumper 4. In Figure 1, the spoiler 3 is in the protruding position E.

[0017] 2, the spoiler 3 is made of a resin material and is formed to a size that has a length that reaches the entire width of the vehicle body 1 and a predetermined vertical dimension (height). The spoiler 3 is supported at both ends in the vehicle body width direction by hinges 5 to the vehicle body 1 so that its position can be freely changed, and is supported at the center position in the vehicle body width direction by a drive unit A so that its position can be freely changed.

[0018] 2, the pair of hinges 5 support the spoiler 3 so that its position can be freely switched around a switching axis X (an example of a rotation axis) extending in the vehicle width direction. In addition, the drive unit A has an operating arm 16 that transmits driving force to the spoiler 3, and the operating arm 16 is supported by a clutch mechanism C that is coaxial with the switching axis X so that its position can be freely switched.

[0019] The vehicle body 1 is equipped with a control device (for example, an ECU, not shown) that controls the attitude of the spoiler 3. Normally, the attitude of the spoiler 3 is in the stored position D, but when the traveling speed of the vehicle body 1 exceeds a set value, the control device controls the electric motor 12 (an example of an actuator) of the drive unit A so that the spoiler 3 moves to the protruding position E. This improves the maneuverability performance of the vehicle body 1 when traveling at high speeds, reduces noise, improves fuel efficiency, etc.

[0020] Furthermore, the control device controls the electric motor 12 so that the spoiler 3 is moved to the retracted position D when the traveling speed of the vehicle body 1 decreases to a predetermined speed that is slower than the set value. This achieves a reduction in air resistance by the spoiler 3.

[0021] [Drive unit] As shown in Figures 3 and 4, the drive unit A has a frame unit 11, an electric motor 12, a pair of drive arms 13, a single intermediate link 14, a pair of driven arms 15, a clutch mechanism C, and an operating arm 16.

[0022] The frame unit 11 has a pair of left and right plate-shaped main body frames 11a made of metal or high-strength resin material, and a connecting frame 11b connecting these.

[0023] The electric motor 12 is provided on the outer surface of one of the body frames 11a (see FIG. 2). The electric motor 12 is housed in a case, and transmits rotational force reduced by a reduction gear (not shown) inside the case to the output shaft 12a. The output shaft 12a is disposed so as to penetrate through the pair of body frames 11a.

[0024] The pair of drive arms 13 are arranged at a predetermined interval in a direction parallel to the switching axis X. Each of the pair of drive arms 13 is connected to the output shaft 12a of the electric motor 12, and rotates integrally with the output shaft 12a.

[0025] The intermediate link 14 is disposed between the pair of drive arms 13 in a direction parallel to the switching axis X, and its input side (the side to which the driving force from the electric motor 12 is applied) is connected to the drive arm 13 by a first connecting shaft R1 so as to be rotatable relative to the drive arm 13. The intermediate link 14 is also disposed between the pair of driven arms 15 in a direction parallel to the switching axis X, and its output side is connected to the driven arm 15 by a second connecting shaft R2 so as to be rotatable relative to the drive arm 13.

[0026] The pair of driven arms 15 are fitted and connected to respective drive-side fitting portions 21b (an example of a first member body) of a pair of drive-side members 21 (an example of a first member) constituting the clutch mechanism C so as to be able to transmit torque. The pair of operating arms 16 are fitted and connected to respective drive-side fitting portions 22b (an example of a second member body) of a pair of driven-side members 22 (an example of a second member) constituting the clutch mechanism C so as to be able to transmit torque. In addition, in the clutch mechanism C, cylindrical shaft support portions 21a (an example of a first member body) of the corresponding pair of drive-side members 21 are supported in through holes 11c formed in the pair of body frames 11a so as to be able to rotate relatively. A detailed configuration of the clutch mechanism C will be described later.

[0027] The drive unit A forms a storage-side restriction surface 11d on the frame unit 11 against which the drive arm 13 abuts when the spoiler 3 is in the storage position D shown in Fig. 3. The drive unit A also forms a contact restriction portion 11g on the frame unit 11 against which the operating arm 16 abuts when the spoiler 3 is in the storage position D. These restrict the rotation of the drive arm 13, and restrict the spoiler 3 from rotating upward (counterclockwise in Fig. 3) from the storage position D.

[0028] Furthermore, when the spoiler 3 is in the protruding position E shown in Figure 4, the drive unit A forms a protruding side regulating surface 11e on the frame unit 11, which restricts the upward displacement of the spoiler 3 (clockwise in Figure 4) by the drive arm 13 abutting against it.

[0029] [Switching operation] Because the drive unit A has this configuration, when the spoiler 3, which is in the storage position D, is operated in the direction of the extended position E, the output shaft 12a is rotated clockwise from the state shown in Figure 3 by the driving force of the electric motor 12, and this rotational force is transmitted sequentially to the drive arm 13, the intermediate link 14, and the driven arm 15, thereby rotating the entire clutch mechanism C in the clockwise direction around the switching axis X.

[0030] This rotation of the clutch mechanism C causes the operating arm 16 to rotate clockwise, thereby setting the spoiler 3 to the protruding position E shown in Figure 4. When the spoiler 3 reaches the protruding position E in this way, the drive arm 13 abuts against the protruding-side regulating surface 11e. This prevents the spoiler 3 (drive arm 13) from rotating clockwise any further, so that the current flowing through the electric motor 12 increases, which is detected by a current sensor (not shown), which stops the supply of electricity to the electric motor 12.

[0031] Conversely, when the spoiler 3, which is in the extended position E shown in FIG. 4, is operated in the direction of the stored position D shown in FIG. 3, the output shaft 12a is rotated counterclockwise in FIG. 4 by the driving force of the electric motor 12, and this rotational force is transmitted sequentially to the drive arm 13, the intermediate link 14, and the driven arm 15, thereby rotating the entire clutch mechanism C counterclockwise around the switching axis X.

[0032] This rotation of the clutch mechanism C causes the operating arm 16 to rotate counterclockwise, thereby setting the spoiler 3 to the storage position D shown in Figure 3. When the spoiler 3 reaches the storage position D in this way, the drive arm 13 abuts against the storage-side restriction surface 11d, and the operating arm 16 abuts against the abutment restriction portion 11g of the frame unit 11. As a result, the spoiler 3 (drive arm 13) does not rotate any further counterclockwise, and the current flowing through the electric motor 12 increases, which is detected by a current sensor (not shown), which stops the supply of electricity to the electric motor 12.

[0033] [Operation limit maintenance structure] 3, when the spoiler 3 is in the storage position D, the rotation center of the first connecting shaft R1 is set below the first limit line L1, which connects the rotation center of the output shaft 12a and the rotation center of the second connecting shaft R2, as viewed in the direction along the switching axis X. This positional relationship is sometimes referred to as the first limit positional relationship.

[0034] 3, the rotation center of the first connecting shaft R1 is located on the opposite side of the rotation center of the output shaft 12a from the second connecting shaft R2, and the drive arm 13 abuts against the storage-side restriction surface 11d. This positional relationship is created by the shape of the intermediate link 14.

[0035] In this first limit positional relationship, even if an unexpected external force acts on the second connecting shaft R2 of the intermediate link 14 to rotate clockwise around the switching axis X, the force accompanying this rotation only acts to rotate the drive arm 13 counterclockwise, and does not act on the drive arm 13 in the clockwise direction.

[0036] For this reason, when the spoiler 3 is in the storage position D, even if a force that rotates the operating arm 16 clockwise about the switching axis X is applied due to an unexpected external force or the weight of the spoiler 3, the force from the intermediate link 14 will not rotate the drive arm 13 clockwise, and the drive arm 13 will remain in contact with the storage-side restriction surface 11d. In other words, when the spoiler 3 is in the storage position D, the spoiler 3 will not rotate clockwise toward the extension position E unless a driving force from the electric motor 12 is applied.

[0037] 4, when the spoiler 3 is in the protruding position E, the rotation center of the first connecting shaft R1 is set below the first limit line L1, which is based on the second limit line L2 connecting the rotation center of the output shaft 12a and the rotation center of the second connecting shaft R2, when viewed in the direction along the switching axis X. This positional relationship is sometimes referred to as the second limit positional relationship.

[0038] In this second limit positional relationship, even if an unexpected external force acts on the operating arm 16 to rotate counterclockwise around the switching axis X, the force accompanying this rotation only acts to rotate the drive arm 13 clockwise, and does not act on the drive arm 13 in the counterclockwise direction.

[0039] For this reason, when the spoiler 3 is in the extended position E, even if a force that rotates the operating arm 16 counterclockwise about the switching axis X due to an unexpected external force or wind pressure in a direction that lifts the spoiler 3 acts, the force from the intermediate link 14 does not act on the drive arm 13 in the counterclockwise direction, and the drive arm 13 remains in contact with the extension-side restriction surface 11e. In other words, when the spoiler 3 is in the extended position E, the spoiler 3 will not rotate counterclockwise toward the stored position D unless a driving force from the electric motor 12 acts on it.

[0040] [Clutch mechanism details] 5, the clutch mechanism C includes a central support shaft 20 arranged coaxially with the switching axis X, drive-side members 21 arranged on the outside of both ends in the direction along the central support shaft 20, driven-side members 22 arranged on the inside of each drive-side member 21, and a coil spring 23 (an example of a biasing member) arranged at a position sandwiched between the pair of driven-side members 22 to apply a biasing force that presses the driven-side member 22 against the drive-side member 21. The convex tooth portion 21T and the concave tooth portion 22T are arranged opposite each other along the switching axis X.

[0041] The coil spring 23 is disposed in a position covering the outer peripheral surface of the central support shaft 20. The outer peripheral surfaces of the shaft support portions 21a, which are the outer end portions of the drive-side member 21, are cylindrical side surfaces centered on the switching axis X, and are supported so as to be rotatable relative to the through-hole 11c of the main frame 11a.

[0042] This clutch mechanism C normally functions as an intermediate shaft that transmits the driving force of the electric motor 12 to the operating arm 16. However, when the vehicle body 1 is traveling and the spoiler 3 at the extended position E comes into contact with a protrusion on the ground or the like and a strong external force acts toward the stored position D, the clutch mechanism C also functions as a torque limiter (overload protection device) that allows the spoiler 3 to be displaced toward the stored position D.

[0043] To enable such overload protection, convex teeth 21T are formed on the driving member 21, concave teeth 22T are formed on the driven member 22, and the biasing force of a coil spring 23 acts on the driven member 22. This causes the concave teeth 22T to approach the convex teeth 21T and engage with each other.

[0044] 5 and 6, the drive-side member 21 is formed with a cylindrical shaft support portion 21a centered on the switching axis X, an octagonal drive-side fitting portion 21b that is a regular octagon when viewed in the direction along the switching axis X, and a cylindrical portion 21c that protrudes from the drive-side fitting portion 21b toward the opposing driven-side member 22 along the direction along the switching axis X. The outer diameter of the cylindrical portion 21c is smaller than the diagonal length of the drive-side fitting portion 21b. A plurality of (three in this embodiment) convex teeth 21T are integrally formed on the outer periphery of the cylindrical portion 21c and protrude toward the driven-side member 22 along the switching axis X. The convex teeth 21T have an isosceles trapezoidal shape when viewed in the radial direction. The shaft support portion 21a, the drive-side fitting portion 21b, the cylindrical portion 21c, and the convex tooth portion 21T that constitute the drive-side member 21 are integrally formed from a first resin material.

[0045] The driven-side member 22 is formed with a cylindrical spring receiving portion 22a (an example of a second member main body) centered on the switching axis X and an octagonal driven-side fitting portion 22b that is a regular octagon when viewed in a direction along the switching axis X. A through-hole (not shown) with a circular cross section centered on the switching axis X is formed from the spring receiving portion 22a to the driven-side fitting portion 22b, and a plurality of (three in this embodiment) recessed tooth portions 22T are formed by cutting out a portion of the inner periphery of this through-hole. The recessed tooth portions 22T face the convex tooth portions 21T along the switching axis X. The recessed tooth portions 22T have an isosceles trapezoidal shape when viewed in a radial direction. When the recessed tooth portions 22T are viewed as a trapezoid, the portions that correspond to the legs are parallel to the portions that correspond to the legs when the convex tooth portions 21T are viewed as a trapezoid. As a result, when the convex tooth portion 21T and the concave tooth portion 22T engage with each other, the abutting portions are in surface contact. The spring receiving portion 22a, the driven-side fitting portion 22b, and the concave tooth portion 22T that constitute the driven-side member 22 are integrally formed from, for example, a second resin material that is harder than the first resin material.

[0046] 5, when the convex toothed portion 21T of the driving-side member 21 and the concave toothed portion 22T of the driven-side member 22 are engaged with each other, the outer peripheral surface of the cylindrical portion 21c of the driving-side member 21 abuts relatively rotatably against the inner peripheral surface of the through-hole of the driven-side member 22. Furthermore, the inner peripheral surface of the cylindrical portion 21c of the driving-side member 21 abuts relatively rotatably against the outer peripheral surface of the central support shaft 20. As a result, the central support shaft 20, the driving-side member 21, and the driven-side member 22 are assembled and integrated so as to be relatively rotatable with each other.

[0047] As partially described above, the shaft support portions 21a of the pair of driving-side members 21 are rotatably supported relative to the corresponding main body frame 11a. The pair of driven arms 15 are fitted and connected to the driving-side fitting portions 21b of the pair of driving-side members 21 so as to be capable of transmitting torque. The pair of operating arms 16 are fitted and connected to the driven-side fitting portions 22b of the pair of driven-side members 22 so as to be capable of transmitting torque.

[0048] In the clutch mechanism C, the convex teeth 21T of the driving-side member 21 and the concave teeth 22T of the driven-side member 22 are normally in mesh with each other, so that the driving force of the electric motor 12 is transmitted from the driven arm 15 to the operating arm 16 via the driving-side member 21 and the driven-side member 22. This causes the spoiler 3 to rotate between the stored position D and the extended position E.

[0049] However, when the vehicle body 1 is traveling, if the spoiler 3 at the extended position E comes into contact with a protrusion on the ground or the like and a strong external force (a load greater than a predetermined value) acts in a short period of time toward the stored position D, the concave tooth portion 22T of the driven-side member 22 of the clutch mechanism C will disengage from the convex tooth portion 21T of the drive-side member 21 against the biasing force of the coil spring 23, thereby cutting off the transmission of the external force and allowing the driven-side member 22 to rotate freely relative to the drive-side member 21. At this time, the abutting points of the convex tooth portion 21T and the concave tooth portion 22T when engaged will be in surface contact. The surface of the concave tooth portion 22T that transmits the external force to the convex tooth portion 21T will be referred to as the pressing tooth surface 22d, and the surface of the convex tooth portion 21T that receives the external force transmitted from the pressing tooth surface 22d will be referred to as the pressure-receiving tooth surface 21d. The pressing tooth surface 22d and the pressure-receiving tooth surface 21d are both parts that form legs of an isosceles trapezoid when viewed in the radial direction, and are opposed to each other.

[0050] An external force acting on the spoiler 3 is transmitted from the pressing tooth surface 22d of the concave tooth portion 22T to the pressure-receiving tooth surface 21d of the drive-side member 21 via the actuating arm 16 and the driven-side member 22 (an example of a load transmission path), causing the driven-side member 22 to slide relative to the drive-side member 21, and the engagement between the convex tooth portion 21T and the concave tooth portion 22T is released. As a result, the actuating arm 16 and the spoiler 3, which have been fitted and connected to the driven-side member 22, rotate until they reach the storage position D. Specifically, the actuating arm 16 rotates until it abuts against the abutment restriction portion 11g of the frame unit 11, and the drive arm 13 abuts against the storage-side restriction surface 11d of the frame unit 11. This makes it possible to prevent unexpected damage to the spoiler 3 due to the action of external force.

[0051] In the clutch mechanism C, the torque (limit torque, load limit value) at which the concave tooth portion 22T of the driven-side member 22 disengages from the convex tooth portion 21T of the driving-side member 21 against the biasing force of the coil spring 23 is determined mainly by four factors: (1) the biasing force of the coil spring 23, (2) the lengths of the convex tooth portion 21T and the concave tooth portion 22T in the direction along the switching axis X (the height of the convex tooth portion 21T and the depth of the concave tooth portion 22T), (3) the size of the base angle when the convex tooth portion 21T and the concave tooth portion 22T are viewed as an isosceles trapezoid in a radial view (the inclination angle of the legs (the pressing tooth surface 22d and the pressure-receiving tooth surface 21d)), and (4) the surface roughness (surface roughness) of the contact surfaces of the convex tooth portion 21T and the concave tooth portion 22T. Of these, the value (4) changes from the initial value due to repeated disengagement between the convex tooth portion 21T and the concave tooth portion 22T. Specifically, the surface roughness of the contact surface decreases, the sliding resistance decreases, and the limit torque of the clutch mechanism C decreases.

[0052] Therefore, in this embodiment, in order to suppress a decrease in the limit torque of the clutch mechanism C even when the engagement between the convex toothed portion 21T and the concave toothed portion 22T is repeatedly released, a protrusion 21e is provided on the pressure-receiving tooth surface 21d of the convex toothed portion 21T. The protrusion 21e is a hemispherical protrusion formed on the tip of the pressure-receiving tooth surface 21d (the end opposite the drive-side fitting portion 21b). As a result, when the engagement between the convex toothed portion 21T and the concave toothed portion 22T is released, the pressing tooth surface 22d of the concave toothed portion 22T abuts and slides against the protrusion 21e rather than the pressure-receiving tooth surface 21d. As a result, the pressing tooth surface 22d of the driven-side member 22 comes into point contact only with the protrusion 21e of the drive-side member 21, and the contact area is extremely smaller than the contact area when the pressing tooth surface 22d and the entire pressure-receiving tooth surface 21d abut and form surface contact. Therefore, the sliding resistance between the pressing tooth surface 22d and the pressure-receiving tooth surface 21d is also reduced. As a result, even if the meshing between the convex tooth portion 21T and the concave tooth portion 22T is repeatedly released, causing the pressing tooth surface 22d and the protrusion 21e to repeatedly slide against each other, and the surface roughness of each of the pressing tooth surface 22d and the protrusion 21e decreases, the degree of reduction in the sliding resistance is small. Therefore, of the above factors (1) to (4) that reduce the limit torque, the influence of factor (4) is reduced, and the reduction in the limit torque is suppressed.

[0053] [Another embodiment] The present invention may be configured as follows in addition to the above-described embodiment (common numbers and symbols as in the embodiment are used to designate components having the same functions as in the embodiment).

[0054] (a) A plurality of protrusions 21e may be formed. Furthermore, the shape of protrusions 21e is not limited to a hemispherical shape, and may be a smoothly bulging shape.

[0055] (b) It is also conceivable to form the protrusion 21e made of a material different from the resin constituting the driving side member 21 in a form attached to the pressure-receiving tooth surface 21d.

[0056] (c) A load transmission path may be configured to transmit the driving force of the electric motor 12 from the driven-side member 22 to the driving-side member 21. In this configuration, the load acts in the opposite direction compared to the configuration described in the embodiment, but the protrusion 21e functions in the same way and can reduce the change in surface roughness (surface roughness) and the change in load that interrupts the transmission of the load.

[0057] (d) The protrusions 21e may be formed on the pressing tooth surface 22d instead of the pressure-receiving tooth surface 21d. Also, they may be formed on the tooth surface of the convex tooth portion 21T opposite the pressure-receiving tooth surface 21d or on the tooth surface of the concave tooth portion 22T opposite the pressing tooth surface 22d.

[0058] (e) Instead of the coil spring 23, a plurality of disc springs may be stacked to bias the driven member 22.

[0059] (f) In the above embodiment, three convex tooth portions 21T are formed on the driving side member 21 and three concave tooth portions 22T are formed on the driven side member 22, but the number of convex tooth portions 21T and concave tooth portions 22T may be four or more, or two.

[0060] In the clutch mechanism C described in the above embodiment, the following configuration is considered.

[0061] <1> One aspect of the clutch mechanism (C) is a clutch mechanism (C) that is connected to a movable member (3) and cuts off the transmission of an external force when a load equal to or greater than a predetermined value acts on the movable member (3), and includes a first member (21) having a convex tooth portion (21T), a second member (22) having a concave tooth portion (22T) with which the convex tooth portion (21T) engages, and a biasing member (23) that biases at least one of the first member (21) and the second member (22) in a direction that causes the convex tooth portion (21T) to engage with the concave tooth portion (22T), and the biasing member (23) increases as the load increases. The first member (21) and the second member (22) are configured to rotate relative to each other in a direction that disengages the convex tooth portion (21T) and the concave tooth portion (22T) against the force, thereby interrupting the transmission of the load, and a load transmission path is configured so that a load is applied from the pressing tooth surface (22d) of the concave tooth portion (22T) to the pressure-receiving tooth surface (21d) of the convex tooth portion (21T), and one of the pressure-receiving tooth surface (21d) and the pressing tooth surface (22d) is provided with a protrusion (21e) that protrudes toward the other of the pressure-receiving tooth surface (21d) and the pressing tooth surface (22d).

[0062] According to this aspect, when an excessive load is applied, the first member 21 and the second member 22 rotate relative to each other in a state in which the protrusion 21e formed on either the pressure-receiving tooth surface 21d of the convex tooth portion 21T or the pressing tooth surface 22d of the concave tooth portion 22T abuts against the other of the pressure-receiving tooth surface 21d of the convex tooth portion 21T or the pressing tooth surface 22d of the concave tooth portion 22T, disengaging the convex tooth portion 21T from the concave tooth portion 22T and interrupting the transmission of the load. At this time, the protrusion 21e wears, and the surface roughness (roughness) of the portion abutting against the tooth surfaces 21d, 22d changes. However, the portion of the protrusion 21e that contacts the other of the pressure-receiving tooth surface 21d and the pressing tooth surface 22d is small compared to the overall area of ​​the pressure-receiving tooth surface 21d. In other words, according to this embodiment, the contact area between the pressure-receiving tooth surface 21d and the pressing tooth surface 22d can be reduced, thereby reducing the effect of surface roughness on the load limit and suppressing variation in the load limit. This makes it possible to realize a clutch mechanism C with reduced variation in the load limit.

[0063] <2> the above <1> In the clutch mechanism (C) described above, it is preferable that the first member (21) and the second member (22) are rotatable relative to each other around the rotation axis and are movable relative to each other along the rotation axis, that the convex tooth portion (21T) and the concave tooth portion (22T) are arranged opposite each other along the rotation axis, and that the biasing member (23) applies a biasing force in a direction that brings the second member (22) and the first member (21) closer to each other.

[0064] According to this embodiment, the biasing force of the biasing member (23) can reliably bring the second member (22) into engagement with the first member (21).

[0065] <3> the above <1> In the clutch mechanism (C) described above, it is preferable that the first member (21) transmits the driving force from the actuator (12), the second member (22) transmits the driving force transmitted from the first member (21) to the movable member, and the biasing member (23) applies a biasing force to the second member (22).

[0066] According to this aspect, the biasing force from the biasing member (23) does not act directly on the first member (21), so that the driving force from the actuator (12) can be reliably transmitted to the first member (21).

[0067] <4> the above <1> from <3> In the clutch mechanism (C) described in any one of the above, it is preferable that the first member body (21a, 21b) and the convex tooth portion (21T) constituting the first member (21) are integrally formed from a first resin material, the second member body (22a, 22b) and the concave tooth portion (22T) constituting the second member (22) are integrally formed from a second resin material that is harder than the first resin material, and the protrusion portion (21e) is formed on the pressure-receiving tooth surface (21d) of the first member (21).

[0068] According to this aspect, since the second resin material constituting the pressing tooth surface (22d) is harder than the first resin material constituting the pressure-receiving tooth surface (21d) and the protrusion (21e), even if the pressing tooth surface (22d) and the protrusion (21e) repeatedly slide against each other, the surface roughness of the pressing tooth surface (22d) is unlikely to decrease, but the surface roughness of the protrusion (21e), which has a smaller area than the pressing tooth surface (22d), is likely to decrease. This further reduces the degree of reduction in sliding resistance. [Industrial Applicability]

[0069] The present invention can be used in a clutch mechanism. [Explanation of symbols]

[0070] 3: spoiler (movable member), 12: electric motor (actuator), 21: driving side member (first member), 21a: shaft support portion (first member main body), 21b: driving side fitting portion (first member main body), 21d: pressure receiving tooth surface, 21e: protrusion, 21T: convex tooth portion, 22: driven side member (second member), 22a: spring receiving portion (second member main body), 21b: driven side fitting portion (second member main body), 22d: pressing tooth surface, 22T: concave tooth portion, 23: coil spring (biasing member), C: clutch mechanism, X: switching axis (rotation axis)

Claims

1. A clutch mechanism that is connected to a movable member and cuts off transmission of an external force when a load equal to or greater than a predetermined value acts on the movable member, a first member having convex teeth; a second member having concave teeth with which the convex teeth engage; a biasing member that biases at least one of the first member and the second member in a direction that causes the convex tooth portion and the concave tooth portion to occlude, the first member and the second member rotate relative to each other in a direction to release the engagement between the convex tooth portion and the concave tooth portion against the biasing force of the biasing member as the load increases, thereby interrupting the transmission of the load; a load transmission path is configured so that the load acts from the pressing tooth surface of the concave tooth portion to the pressure-receiving tooth surface of the convex tooth portion, and a clutch mechanism is provided on either the pressure-receiving tooth surface or the pressing tooth surface with a protrusion that protrudes toward the other of the pressure-receiving tooth surface or the pressing tooth surface.

2. the first member and the second member are relatively rotatable about a rotation axis and relatively movable along the rotation axis, 2. The clutch mechanism according to claim 1, wherein the convex tooth portion and the concave tooth portion are arranged opposite each other along the rotation axis, and the biasing member applies a biasing force in a direction that brings the second member and the first member closer together.

3. a driving force from an actuator is transmitted to the first member, and the second member transmits the driving force transmitted from the first member to the movable member; 2. The clutch mechanism according to claim 1, wherein the biasing member applies a biasing force to the second member.

4. a first member body and the convex tooth portion constituting the first member are integrally formed from a first resin material, a second member body and the concave tooth portion constituting the second member are integrally formed of a second resin material harder than the first resin material, 4. The clutch mechanism according to claim 1, wherein the protrusion is formed on the pressure-receiving tooth surface of the first member.

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