WO2005113290A1

WO2005113290A1 - Pivoting actuator for automotive outsider mirror

Info

Publication number: WO2005113290A1
Application number: PCT/KR2004/001890
Authority: WO
Inventors: Hyuk-Joon Ro
Original assignee: Pro Quip International Korea Co., Ltd
Priority date: 2004-05-20
Filing date: 2004-07-27
Publication date: 2005-12-01
Also published as: KR100586003B1; KR20050110971A

Abstract

The object of this invention is to provide a pivoting actuator of a side rear view mirror assembly for vehicles. The pivoting actuator of the present invention includes a first pivot unit which has a base flange and a base shaft, and a second pivot unit which has a frame and a drive unit. The pivoting actuator further includes a coupling drive gear rotatably fitted over the base shaft, a first cam disk removably coupled to one of upper and lower surfaces of the coupling drive gear, and a second cam disk removably coupled to one of upper and lower surfaces of the first cam disk. The pivoting actuator further includes a spring fitted over the base shaft, at least one rotation limiting protrusion provided on the second cam disk, and a stopper provided on the frame at a predetermined position corresponding to the rotation limiting protrusion of the second cam disk.

Description

PIVOTING ACTUATOR FOR AUTOMOTIVE OUTSIDER MIRROR

Technical Field

The present invention relates, in general, to pivoting actuators of side rear view mirror assemblies for vehicles and, more particularly, to a pivoting actuator which pivots a side rear view mirror forwards and rearwards with respect to a vehicle body.

Background Art

Generally, side rear view mirror assemblies, which are one of the components of vehicles, are mounted at the front of the outer surface of both front doors so as to help drivers observe traffic conditions to the left and right rear sides without turning their heads while driving vehicles . Such a side rear view mirror assembly includes a mirror housing, in which a mirror is provided, and a mirror direction adjusting unit which is coupled to a rear surface of the mirror to adjust the direction of the mirror upwards, downwards, leftwards and rightwards. The side rear view mirror assembly further includes a pivoting actuator which pivots a mirror housing forwards and rearwards with respect to a vehicle body. The pivoting actuator has two operating units which are mounted such that the two operating units are rotatable with respect to each other. Recently, pivoting actuators, which include a power driving structure consisting of an electric motor and a power transmission system to rotate the two operating units with respect to each other, are becoming popularized. As shown in FIG. 2, when traveling, parking or stopping a vehicle, a mirror housing 3 is pivoted in a direction so that an outer end of the mirror housing 3 protrudes from the side of the vehicle body 1 at a predetermined angle (to position A of FIG. 2) . In the particular case, for example, of parking the vehicle in a small place, the outer end of the mirror housing 3 is rotated to a position adjacent to the side of the vehicle body 1 (to position B of FIG. 2) . As such, when the mirror housing 3 is pivoted rearwards to a position adjacent to the side of the vehicle body 1, the mirror housing 3 is said to be placed at a fold-in position (position B of FIG. 2) . Conversely, when the mirror housing 3 is pivoted forwards and, thus, protrudes outwards from the sidewall of the vehicle body 1, the mirror housing 3 is said to be placed at a fold-out position (position A of FIG. 2) . Generally, the fold-out position is a normal position. Furthermore, in consideration of stability, the pivoting actuator is constructed such that, when external force due to an outside obstacle is applied to the mirror housing 3, the mirror housing 3 can be pivoted at a large angle (to position C of FIG. 2) towards the sidewall of the vehicle body 1, thus preventing the mirror housing 3 from being damaged. As such, when the mirror housing 3 is pivoted at a large angle towards the vehicle body 1, the mirror housing 3 is said to be placed in a fold-over position (position C of FIG. 2) . Furthermore, a process of returning the mirror housing 3 from the fold-over position to the normal position is called folding back. Meanwhile, in the pivoting actuator operated by the power driving method, it is necessary to involve a passive driving system in the pivoting actuator such that the mirror housing can be pivoted by external force, for example, by the adjustment of a user or by an outside obstacle. Such conventional pivoting actuators were proposed in US Patent Nos. 6,130,514 and 5,625,502 and PCT Publication No. WO 03/011642. As shown in FIG. 1, such a conventional pivoting actuator includes a first pivot unit 11 which is mounted on a support 2 mounted to a sidewall of a vehicle body 1, and a second pivot unit 12 which is installed in a mirror housing 3. The irst and second pivot units 11 and 12 are disposed such that they are rotatable around a rotating shaft 14 with respect to each other. The first pivot unit 11 includes a base flange 101 and a base shaft 102. The second pivot unit 12 includes a frame 200, and a drive unit (not shown) which is provided in the frame 200 and transmits power to the base shaft 102. The drive unit (not shown) has an electric motor and a power transmission gear set. Furthermore, both a power decoupling structure (not shown) , which decouples the base shaft 102 from the drive unit (not shown) to implement the above-mentioned passive pivoting motion so that the first and second pivot units 11 and 12 are rotated with respect to each other by a passive drive force, and a rotation limiting structure (not shown) , which limits a rotating angle of the mirror housing during the passively pivoting motion, are provided between the first and second pivot units 11 and 12. However, in the conventional pivoting actuator, the power decoupling structure and the rotation limiting structure are provided at the junction between the upper surface of the base flange 101 and the lower surface of the frame 200 which rotatably contact each other. Therefore, during a passive pivoting motion, the mirror housing 3 protrudes upwards. As such, the conventional pivoting actuator is problematic in that because the mirror housing 3 protrudes upwards during a passive pivoting motion, the mirror housing 3 may easily be damaged by torque applied to the mirror housing 3 by an unexpected force. Furthermore, in the conventional pivoting actuator, the power decoupling structure and the rotation limiting structure are very complex. As a result, the required number of elements constituting the actuator is increased. Thereby, the conventional pivoting actuator is problematic in that workability is reduced, the manufacturing process is complicated, and the manufacturing costs are increased.

Disclosure of the Invention

Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a pivoting actuator of a side rear view mirror assembly for vehicles in which a power decoupling structure and a rotation limiting structure are provided in a frame so that a mirror housing is prevented from protruding upwards during a passive pivoting motion, thus preventing the mirror housing from being damaged by an external force. Another object of the present invention is to provide a pivoting actuator of a side rear view mirror assembly for vehicles which has a simple and compact structure so that the required number of elements constituting the actuator is reduced, thus simplifying a manufacturing process, reducing manufacturing costs, and enhancing workability. In order to accomplish the above object, the present invention provides a pivoting actuator of a side rear view mirror assembly for vehicles, including a first pivot unit, mounted to a support, which is fastened to a sidewall of a vehicle body or to a mirror housing, which is coupled to the support, and a second pivot unit, which is coupled to a remaining one of the support and the mirror housing, the first and second pivot units being rotatable with respect to each other so that the mirror housing is rotatable forwards and rearwards on the support, wherein the first pivot unit includes a base flange, and a base shaft, with a plurality of splines provided on a circumferential outer surface of the base shaft and spaced apart from each other at regular intervals, the second pivot unit includes a frame and a drive unit provided in the frame, the drive unit has an electric motor and a power transmission gear set for transmitting power from the electric motor, the pivoting actuator further includes: a coupling drive gear rotatably fitted over a circumferential outer surface of the base shaft and coupled to the power transmission gear set of the drive unit; a first cam disk removably coupled to one of upper and lower surfaces of the coupling drive gear, with a plurality of key holes formed in a circumferential inner surface of the first cam disk so that the splines of the base shaft are inserted into the key holes; a second cam disk removably coupled to one of upper and lower surfaces of the first cam disk and rotatably fitted over the base shaft; a spring axially fitted over the base shaft, thus applying an elastic force to the coupling drive gear and first and second cam disks such that the coupling drive gear and first and second cam disks maintain a state of being coupled together; at least one rotation limiting protrusion provided at a predetermined position on the second cam disk; and a stopper provided on the frame of the second pivot unit at a predetermined position corresponding to the rotation limiting protrusion of the second cam disk. Preferably, both the splines of the base shaft and the key holes of the first cam disk may be tapered in longitudinal directions of the base shaft. Preferably, the power transmission gear set may include: a first worm provided on an output shaft of the electric motor; a first worm gear engaging with the first worm; a pair of second worms coaxially coupled at opposite side surfaces of the first worm gear; a pair of second worm gears engaging with the respective second worms; and a pair of spur gears coupled to lower surfaces of the respective second worm gears. Preferably, the pivoting actuator may further include: a plurality of first locking grooves and a plurality of first locking protrusions corresponding to each other and respectively provided on an upper surface of the coupling drive gear and a lower surface of the first cam disk; and a plurality of second locking grooves and a plurality of second locking protrusions corresponding to each other and respectively provided on a lower surface of the second cam disk and an upper surface of the first cam disk, so that the first cam disk is removably coupled to the upper surface of the coupling drive gear, and the second cam disk is removably coupled to the upper surface of the first cam disk, wherein opposite sidewalls of each of the locking grooves and the locking protrusions are inclined at predetermined angles. Preferably, the pivoting actuator may further include: a plurality of first locking grooves and a plurality of first locking protrusions corresponding to each other and respectively provided on a lower surface of the coupling drive gear and an upper surface of the first cam disk; and a plurality of second locking grooves and a plurality of second locking protrusions corresponding to each other and respectively provided on an upper surface of the second cam disk and a lower surface of the first cam disk, so that the first cam disk is removably coupled to the lower surface of the coupling drive gear, and the second cam disk is removably coupled to the lower surface of the first cam disk, wherein opposite sidewalls of each of the locking grooves and the locking protrusions are inclined at predetermined angles. Preferably, the number of first locking grooves and first locking protrusions, corresponding to each other, provided in the coupling drive gear and the first cam disk may be greater than the number of second locking grooves and second locking protrusions, corresponding to each other, provided in the first and second cam disks. Preferably, Heights of the second locking grooves and second locking protrusions, corresponding to each other, provided in the first and second cam disks may be greater than heights of the first locking grooves and first locking protrusions, corresponding to each other, provided in the coupling drive gear and the first cam disk. Preferably, the pivoting actuator may further includes: a third locking groove and a third locking protrusion provided as a pair at diametrically opposite positions on the surface of the second cam disk which removably contacts the first cam disk; and a fourth locking protrusion and a fourth locking groove provided at diametrically opposite positions on the contact surface of the first cam disk, so that the fourth locking protrusion of the first cam disk is inserted into the third locking groove of the second cam disk and the third locking protrusion of the second cam disk is inserted into the fourth locking groove of the first cam disk. In the present invention, a power decoupling structure and a rotation limiting structure are provided in a frame so that a mirror housing is prevented from protruding upwards during a passive pivoting motion, thus preventing the mirror housing from being damaged by an external force. Furthermore, the present invention has a simple and compact structure so that the required number of elements constituting the actuator is reduced, thus simplifying a manufacturing process, reducing manufacturing costs, and enhancing workability.

Brief Description of the Drawings FIG. 1 is a schematic view showing the construction of a pivoting actuator of a conventional side rear view mirror assembly; FIG. 2 is a view showing a pivoting motion of a conventional mirror housing; FIG. 3 is an exploded perspective view of a pivoting actuator, according to the present invention; FIG. 4 is a sectional view showing an assembled pivoting actuator, according to a first embodiment of the present invention; FIG. 5 is plan views showing a coupling drive gear and first and second cam disks of the pivoting actuator according to the first embodiment of the present invention; FIG. 6 is a sectional view showing a power decoupling structure of a pivoting actuator, according to a second embodiment of the present invention; FIG. 7 is plan views showing a coupling drive gear and first and second cam disks of the pivoting actuator according to the second embodiment of the present invention; FIG. 8 is a perspective view showing a second cam disk of the pivoting actuator according to a modification of the present invention; FIG. 9 is a perspective view showing both a rotation limiting protrusion, provided on a surface of the second cam disk, and a stopper, provided on a frame, according to the present invention; FIG. 10 is a side view showing a key hole of the first cam disk and a spline of a base shaft according to the present invention; and FIG. 11 is a perspective view showing a power transmission gear set of the pivoting actuator according to the present invention. *Description of the elements in the drawings* 1: vehicle body 2: support

3 : mirror housing 10 : pivoting actuator 11,12: first and second pivot units 35: coupling drive gear 41: first cam disk 43 : second cam disk

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the attached drawings. Typically, as shown in FIG. 1, a pivoting actuator 10 includes a first pivot unit 11 which is mounted to an upper surface of a support 2 fastened to a sidewall of a vehicle body 1, and a second pivot unit 12 which is mounted in a mirror housing 3. The first and second pivot units 11 and 12 are disposed such that they are rotatable with respect to each other around a rotating axis 14. On the other hand, a pivoting actuator 10 of the present invention is not limited to the structure illustrated in FIG. 1. That is, the present invention may have a structure such that a first pivot unit 11 may be mounted in a mirror housing 3, and a second pivot unit 12 may be mounted to a support 2 of a vehicle body 1, unlike the structure of FIG. 1. As such, the pivoting actuator 10 of the present invention includes the first and second pivot units 11 and 12 which are respectively mounted to the support 2, which is fastened to a sidewall of the vehicle body 1, or to the mirror housing 3, which is coupled to the support 2, or vice-versa. The first and second pivot units 11 and 12 are rotatable with respect to each other so that the mirror housing 3 is rotatable forwards and rearwards on the support 2. As shown in FIG. 3, the first pivot unit 11 includes a base flange 101 and a base shaft 102 having a hollow cylindrical shape. The base flange 101 is fastened at a lower surface thereof to the support 2 or the mirror housing 3 by a coupling means. A plurality of splines 102a is provided around a circumferential outer surface of the base shaft 102. The splines 102a are spaced apart from each other at regular intervals in a circumferential direction and inserted into key holes 42 of a first cam disk 41, which will be explained later herein. The second pivot unit 12 includes a frame 200, which is selectively mounted to the support 2 of the vehicle body 1 or the mirror housing 3, and a drive unit 20 which is provided in the frame 200. Referring to FIG. 3, the frame 200 has an upper frame 201, an intermediate frame 202 and a lower frame 203. The lower frame 203 has on a lower surface thereof a ring shaped flange 204 having an opening through which the base shaft 102 passes. The upper and intermediate frames 201 and 202 are coupled to an upper surface of the lower frame 203. The drive unit 20, which pivots the mirror housing 3 using a driving force thereof, is interposed between the upper and intermediate frames 201 and 202. The drive unit 20 includes an electric motor 25 and a power transmission gear set 26 which transmits power from the electric motor 25 to the base shaft 102. Preferably, as shown in FIG. 11, the power transmission gear set 26 includes a first worm 26a which is provided on an output shaft of the electric motor 25, and a first worm gear 26b which engages with the first worm 26a. The power transmission gear set 26 further includes a pair of second worms 26c which are coaxially coupled at opposite side surfaces of the first worm gear 26b, a pair of second worm gears 26d which respectively engage with second worms 26c, and a pair of spur gears 26e which are integrally coupled to lower surfaces of respective second worm gears 26d. In the power transmission gear set 26 having the above-mentioned construction, because each second worm gear 26d has inclined teeth, vibration and noise are reduced, abrasion is even, and smooth power transmission is achieved. However, if the second worm gears 26d having inclined gear teeth directly engage with a coupling drive gear 35 which will be described later herein, the coupling drive gear 35 thrusts in an axial direction so that upward or downward deflection of the coupling drive gear 35 is caused. As a result, power loss becomes great. Therefore, in the present invention, the spur gears 26e are integrated with the lower surfaces of the second worm gears 26d, and the coupling drive gear 35 engages with the spur gears 26e, so that the coupling drive gear 35 is prevented from thrusting in an axial direction, thus minimizing the loss of power. The coupling drive gear 35 is elastically supported by a spring 33 and is rotatably fitted over the base shaft 102. The coupling drive gear 35 is disposed on a longitudinally intermediate position of the base shaft 102. Teeth of the coupling drive gear 35 engage with the spur gears 26e of the power transmission gear set 26. The spring 33 is fitted over the base shaft 102 to apply an elastic force to elements in an axial direction and is disposed above or below the coupling drive gear 35. Meanwhile, in the pivoting actuator of the present invention, a power decoupling structure, which decouples the coupling drive gear 35, which is connected to the power transmission gear set 20, from the base shaft 102, is provided at a position adjacent to the coupling drive gear 35 mounted in the frame 200, thus allowing the mirror housing 3 to be passively pivoted, but is not provided at the junction between the upper surface of the base flange 101 and the lower surface of the frame 200 which are rotatable with respect to each other. Therefore, the present invention is characterized in that the mirror housing 3 is prevented from protruding upwards while being passively pivoted. To realize such a power decoupling structure, in a first embodiment of the present invention, as shown in FIGS. 3 and 4, a first cam disk 41 is provided on the upper surface of the coupling drive gear 35, and a second cam disk 43 is provided on the upper surface of the first cam disk 41. The power decoupling structure according to the first embodiment may be adapted for a small vehicle such as a passenger car. As shown in FIG. 5a, a plurality of locking grooves 35a is formed at predetermined positions in the upper surface of the coupling drive gear 35. Opposite sidewalls of each locking groove 35a are inclined at predetermined angles . As shown in FIG. 5b, a plurality of locking protrusions 41a is provided at predetermined positions under the lower surface of the first cam disk 41 so that the locking protrusions 41a are inserted into the locking grooves 35a of the coupling drive gear 35. Opposite sidewalls of each locking protrusion 41a are also inclined at predetermined angles to correspond to the inclined sidewalls of each locking groove 35a of the coupling drive gear 35. Furthermore, a plurality of locking protrusions 41b is provided on an upper surface of the first cam disk 41. Opposite sidewalls of each locking protrusion 41b are inclined at predetermined angles. Moreover, a plurality of key holes 42 is formed in a circumferential inner surface of the first cam disk 41 so that the splines 102a of the base shaft 102 are inserted into the key holes 42. The first cam disk 41, which is fitted over the base shaft 102, can be interlocked with the base shaft 102 by insertion of the splines 102a of the base shaft 102 into the key holes 42 of the first cam disk 41. The second cam disk 43 is rotatably fitted over the base shaft 102. As shown in FIG. 5c, a plurality of locking grooves 43a, into which the locking grooves 41b of the first cam disk 41 are removably inserted, is formed in a lower surface of the second cam disk 43, so that the second cam disk 43 is removably coupled to the upper surface of the first cam disk 41. Opposite sidewalls of each locking groove 43a of the second cam disk 43 have inclined shapes to correspond to the inclined opposite sidewalls of each locking protrusion 41b of the first cam disk 41. FIG. 6 is a sectional view showing a power decoupling structure according to a second embodiment of the present invention. As shown in FIG. 6, in the power decoupling structure according to the second embodiment of the present invention, a first cam disk 41 is disposed under a lower surface of a coupling drive gear 35, and a second cam disk 43 is disposed under a lower surface of the first cam disk 41. The power decoupling structure according to the second embodiment may be used in a large vehicle such as a large truck. As shown in FIG. 7a, a plurality of locking grooves 35b is formed in the lower surface of the coupling drive gear 35. Opposite sidewalls of each locking groove 35b are inclined at predetermined angles. As shown in FIG. 7b, a plurality of locking protrusions 41c is provided at predetermined positions on an upper surface of the first cam disk 41 so that the locking protrusions 41c are inserted into the locking grooves 35b of the coupling drive gear 35. Opposite sidewalls of each locking protrusion 41c are also inclined at predetermined angles to correspond to the inclined sidewalls of each locking groove 35b of the coupling drive gear 35. Furthermore, a plurality of locking protrusions 41d is provided on the lower surface of the first cam disk 41. Opposite sidewalls of each locking protrusion 41d are inclined at predetermined angles. Moreover, a plurality of key holes 42 is formed in a circumferential inner surface of the first cam disk 41 so that the splines 102a provided on the base shaft 102 are inserted into the key holes 42. The first cam disk 41, which is fitted over the base shaft 102, can be interlocked with the base shaft 102 by insertion of the splines 102a of the base shaft 102 into the key holes 42 of the first cam disk 41. The second cam disk 43 is rotatably fitted over the base shaft 102. As shown in FIG. 7c, a plurality of locking grooves 43c, into which the locking protrusions 41d of the first cam disk 41 are removably inserted, is formed in an upper surface of the second cam disk 43. Opposite sidewalls of each locking groove 43c of the second cam disk 43 have inclined shapes to correspond to the inclined opposite sidewalls of each locking protrusion 4Id of the first cam disk 41. Meanwhile, in each of the first and second embodiments, as shown in FIG. 9, at least one rotation limiting protrusions 43b is provided on a circumferential outer surface of the second cam disk 43. Stoppers 45 are provided in the frame 200 (in the case of FIG. 9, being provided in the intermediate frame 202) , so that the stoppers 45 block the rotation limiting protrusions 43b of the second disk 43. Thus, fold-in and fold-out motion of the pivoting actuator of the present invention is limited within a predetermined angular range both by the rotation limiting protrusions 43b of the second cam disk 43 and by the stoppers 45 of the frame 200. In the present invention, the locking protrusions and locking grooves for realizing the removable coupling of the first cam disk 41, the coupling drive gear 35 and the second cam disk 43 to each other may be modified into various shapes and structures without being limited to that described for the first and second embodiments. The operation of the power decoupling structure of the pivoting actuator according to each of the first and second embodiments of the present invention will be explained herein below. First, in the case that no external force is applied to the mirror housing 3 (in the case that the pivoting actuator is in a state such that the pivoting motion of the mirror housing 3 is executed by a power driving method) , the coupling drive gear 35 and first and second cam disks 41 and 43 are in a state of being coupled together by the elasticity of the spring 33. Thereby, the coupling drive gear 35, which is coupled to the power transmission gear set 26 of the drive unit 20, maintains the state of being interlocked with the base shaft 102 by the first cam disk 41. Therefore, the power of the drive unit 20 is transmitted to the base shaft 102 through the coupling drive gear 35, so that the mirror housing 3 executes a pivoting motion using electrical power. In the case that external force is applied to the mirror housing 3 (when the mirror housing 3 is passively pivoted) , if predetermined external force is applied to the mirror housing 3 such that the mirror housing 3 is pivoted to a fold-in or fold-out position from the state in which the first cam disk 41 and the coupling drive gear 35 are coupled to each other by both the locking protrusions 41a, 41c and the locking grooves 35a, 35b, the first cam disk 41 overcomes the elasticity of the spring 33. That is, the locking protrusions 41a, 41c of the first cam disk 41 slide outwards along the inclined sidewalls of the locking grooves 35a, 35b of the coupling drive gear 35. As a result, a first separation process such that the first cam disk 41 is unlocked from the coupling drive gear 35 is executed. Then, the base shaft 102 and the first cam disk 41 are decoupled from the drive unit 20, and the coupling drive gear 35, coupled to the drive unit 20, enters a state of being freely rotated with respect to the base shaft 102. Therefore, the drive unit 20 enters an idle state, so that the passive pivoting motion (the fold-in or fold-out motion) of the mirror housing 3 is executed. However, even if the first separation process such that the first cam disk 41 is decoupled from the coupling drive gear 35 is executed when the mirror housing is passively pivoted to the fold-in or fold-out position, because the second cam disk 43 still maintains the state of being coupled to the first cam disk 41 and the rotation of the rotation limiting protrusion 43b of the second cam disk 43 is limited by the stopper 45 provided in the frame 200, the fold-in or fold-out pivoting motion of the mirror housing is limited within a predetermined angular range. Meanwhile, in the case that the fold-over pivoting motion of the mirror housing 3 is executed by external force larger than that required for the above-mentioned fold-in or fold-out pivoting motion of the mirror housing 3, the first separation process, in which the first cam disk 41 disengages from the coupling drive gear 35 is executed and, simultaneously, the locking protrusions 41b, 41d of the first cam disk 41 slide outwards along the inclined sidewalls of the locking grooves 43a, 43c of the second cam disk 43. As a result, a second separation process such that the first cam disk 41 and the second cam disk 43 are decoupled from each other is executed. As such, the second cam disk 43 is completely decoupled from both the first cam disk 41 and the base shaft 102 through the second separation process of the first and second cam disks 41 and 43. Thus, the second cam disk 43 enters a state of being freely rotated with respect to the base shaft 102. Furthermore, the first cam disk 41 and the base shaft 102 become free from the rotation limiting structure including the rotation limiting protrusion 43b of the second cam disk 43 and the stopper 45. Therefore, the fold-over or fold-back pivoting motion is executed. Meanwhile, the above-mentioned fold-over or fold-back pivoting motion is limited within a predetermined angular range by a separate rotation limiting structure provided at the junction surface between the support 2 of the vehicle body 1 and the lower surface of the frame 200. Such a rotation limiting structure is well known to those skilled in the art. Preferably, the number of locking protrusions 41a, 41c and locking grooves 35a, 35b, which are provided in the junction surface between the first cam disk 41 and the coupling drive gear 35, is greater than the number of locking protrusions 41b, 4Id and locking grooves 43a, 43c which are provided in the junction surface between the first cam disk 41 and the second cam disk 43. Due to this structure, static pressure between the first cam disk 41 and the coupling drive gear 35 is greater than static pressure between the second cam disk 43 and the first cam disk 41. Thus, when predetermined external force is applied to the mirror housing 3, the first cam disk 41 is decoupled from the coupling drive gear 35 before the first cam disk 41 is decoupled from the second cam disk 43. In other words, the present invention is constructed such that, when predetermined external force is applied to the mirror housing 3, the first separation process between the first cam disk 41 and the coupling drive gear 35 is first executed and then the second separation process between the first cam disk 41 and the second cam disk 43 is executed. Furthermore, it is preferable that the heights (h2) of the locking protrusions 41b, 4Id of the first cam disk 41 corresponding to the locking grooves 43a, 43c of the second cam disk 43 be greater than the heights (hi) of the locking protrusions 41a, 41c of the first cam disk 41 corresponding to the locking grooves 35a, 35b of the coupling drive gear 35. This prevents the second separation between the first and second cam disks 41 and 43 from undesirably occurring due to a small external force. That is, due to the above-mentioned structure, the passive fold- over pivoting motion of the mirror housing is prevented from being too easily executed. Meanwhile, as shown in FIG. 8, a locking groove 43e and a locking protrusion 43f may be symmetrically provided as a pair at diametrically opposite positions on the surface of a second cam disk 43 which removably contacts a first cam disk. A locking protrusion 41e, which is inserted into the locking groove 43e of the second cam disk 43, and a locking groove 41f, into which the locking protrusion 43f of the second cam disk 43 is inserted, may be provided at diametrically opposite positions on the contact surface of a first cam disk 41. In this case, if external force is applied to the mirror housing such that the mirror housing is passively pivoted to a fold-over position from the state in which the locking protrusion 41e of the first cam disk 41 is seated in the locking groove 43e of the second cam disk 43 and the locking protrusion 43f of the second cam disk 43 is seated in the locking groove 41f of the first cam disk 41, the locking protrusion and locking groove 41e and 41f of the first disk 41 and the locking groove and locking protrusion 43e and 43f of the second cam disk 43 slide with respect to each other. Thus, the first cam disk 41 and the second cam disk 43 are decoupled from each other, so that the fold- over pivoting motion is executed. During the fold-over pivoting motion, if the locking protrusion 41e of the first cam disk 41 comes into contact with the locking protrusion 43f of the second cam disk 43, the mirror housing does not pivot any further. As such, the present invention is characterized in that the fold-over pivoting motion of the mirror housing is limited within a predetermined angular range. Furthermore, it is preferable that both each splines 102a of the base shaft 102 and each key hole 42 of the first cam disk 41 be tapered in upward or downward directions at a predetermined angle (0) , as shown in FIG. 10. Due to the tapered structure of the splines 102a and the key holes 42, the mobility of the first cam disk 41 is increased so that the first cam disk 41 can be easily coupled or decoupled both to the second cam disk 43 and to the coupling drive gear 35. Meanwhile, as shown in FIG. 3, a stop washer 44, which has a plurality of holding protrusions extending inwards from an inner edge of the stop washer 44, is fitted over the circumferential outer surface of the base shaft 102, thus preventing the spring 33 from becoming undesirably removed from the base shaft 102. Furthermore, as shown in FIG. 3, thrust bearings 54 are provided on and under the ring shaped flange 204 of the lower frame 203. Thus, the thrust bearings 54 support the axial loads of the coupling drive gear 35 and the base flange 101 which respectively are in surface contact with the upper and lower surfaces of the ring shaped flange 204 of the lower frame 203, thereby helping the pivoting motion be smoothly executed. Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.

Claims

1. A pivoting actuator of a side rear view mirror assembly for vehicles, comprising: a first pivot unit, mounted to a support, which is fastened to a sidewall of a vehicle body or to a mirror housing, which is coupled to the support, and a second pivot unit, which is coupled to a remaining one of the support and the mirror housing, the first and second pivot units being rotatable with respect to each other so that the mirror housing is rotatable forwards and rearwards on the support, wherein the first pivot unit comprises: a base flange; and a base shaft, with a plurality of splines provided on a circumferential outer surface of the base shaft and spaced apart from each other at regular intervals, the second pivot unit comprises: a frame; and a drive unit provided in the frame, the drive unit comprising an electric motor and a power transmission gear set for transmitting power from the electric motor, and the pivoting actuator further comprises: a coupling drive gear rotatably fitted over an outer surface of the base shaft and coupled to the power transmission gear set of the drive unit; a first cam disk removably coupled to one of upper and lower surfaces of the coupling drive gear, with a plurality of key holes formed in a circumferential inner surface of the first cam disk so that the splines of the base shaft are inserted into the key holes; a second cam disk removably coupled to one of upper and lower surfaces of the first cam disk and rotatably fitted over the base shaft; a spring axially fitted over the base shaft, thus applying an elastic force to the coupling drive gear and first and second cam disks such that the coupling drive gear and first and second cam disks maintain a state of being coupled together; at least one rotation limiting protrusion provided at a predetermined position on the second cam disk; and a stopper provided on the frame of the second pivot unit at a predetermined position corresponding to rotation limiting protrusion of the second cam disk.

2. The pivoting actuator according to claim 1, wherein both the splines of the base shaft and the key holes of the first cam disk are tapered in longitudinal directions of the base shaft.

3. The pivoting actuator according to claim 1 or 2, wherein the power transmission gear set comprises: a first worm provided on an output shaft of the electric motor; a first worm gear engaging with the first worm; a pair of second worms coaxially coupled at opposite side surfaces of the first worm gear; a pair of second worm gears engaging with the respective second worms; and a pair of spur gears coupled to surfaces of the respective second worm gears.

4. The pivoting actuator according to claim 3, further comprising: a plurality of first locking grooves and a plurality of first locking protrusions corresponding to each other and respectively provided on an upper surface of the coupling drive gear and a lower surface of the first cam disk; and a plurality of second locking grooves and a plurality of second locking protrusions corresponding to each other and respectively provided on a lower surface of the second cam disk and an upper surface of the first cam disk, so that the first cam disk is removably coupled to the upper surface of the coupling drive gear, and the second cam disk is removably coupled to the upper surface of the first cam disk, wherein opposite sidewalls of each of the locking grooves and the locking protrusions are inclined at predetermined angles.

5. The pivoting actuator according to claim 3, further comprising: a plurality of first locking grooves and a plurality of first locking protrusions corresponding to each other and respectively provided on a lower surface of the coupling drive gear and an upper surface of the first cam disk; and a plurality of second locking grooves and a plurality of second locking protrusions corresponding to each other and respectively provided on an upper surface of the second cam disk and a lower surface of the first cam disk, so that the first cam disk is removably coupled to the lower surface of the coupling drive gear, and the second cam disk is removably coupled to the lower surface of the first cam disk, wherein opposite sidewalls of each of the locking grooves and the locking protrusions are inclined at predetermined angles.

6. The pivoting actuator according to claim 5, wherein the number of first locking grooves and first locking protrusions, corresponding to each other, provided in the coupling drive gear and the first cam disk is greater than the number of second locking grooves and second locking protrusions, corresponding to each other, provided in the first and second cam disks.

7. The pivoting actuator according to claim 5, wherein heights of the second locking grooves and second locking protrusions, corresponding to each other, provided in the first and second cam disks are greater than heights of the first locking grooves and first locking protrusions, corresponding to each other, provided in the coupling drive gear and the first cam disk.

8. The pivoting actuator according to claim 6 or 7, further comprising: a third locking groove and a third locking protrusion provided as a pair at diametrically opposite positions on the surface of the second cam disk which removably contacts the first cam disk; and a fourth locking protrusion and a fourth locking groove provided at diametrically opposite positions on the contact surface of the first cam disk, so that the fourth locking protrusion of the first cam disk is inserted into the third locking groove of the second cam disk and the third locking protrusion of the second cam disk is inserted into the fourth locking groove of the first cam disk.