DRIVE UNIT FOR ELECTRICALLY DRIVEN REMOTE-CONTROLLED MIRROR

Abstract: In a drive unit for an electric remote control mirror, a pair of screw rods (16) for slanting the mirror (10) around horizontal and vertical axes is disposed movably forwardly and backwardly within the drive casing (14). Within the drive casing (14), there is disposed a pair of drive motors (20), of which the rotations are transmitted through a reduction gear group (52) to a pair of rota­ tion members (30), of which the rotations are converted into forward and backward movements of the pair of screw rods (16). Each of the rotation members (30) is composed of a shaft (36) having a pair of arm members (34) with a screw thread which is in mesh with a screw thread (24) formed on the inner circumference of the screw rod (16), a hollow cylindrical rotation body (38) having a gear (46) in mesh with the reduction gear group (52) and a space (18) in which the screw rod (16) is placed, and a plurality of connection members (40) extending radially and which provide a connection between the base of the shaft (36) and the lower end of the rotation body (38), each of the connection members (40) being formed relatively thin so that when the shaft (36) is applied with a force from the screw rod (16), the connection member (40) is resiliently deformable. When each screw rod (16) is moved forwardly or backwardly, the shaft (36) is applied with a force from the screw rod (16), but since the plural connec­ tion members (40) are resiliently deformed, the shaft (36) can be slanted axially so that each screw rod (16) can positively follow up with the pivoting of the mirror.

Description: BACKGROUND OF THE INVENTION a) Field of the Invention: The present invention relates to a drive unit for electrically driven remote-controlled mirror, and more particularly to an improved drive mechanism which slants a mirror body pivotably supported inside a mirror housing and to which a mirror is secured, around a horizontal and vertical axes passing through the central axis of a pivot. b) Related Art Statement: In a conventional drive unit for slanting the mirror of an electric remote control mirror apparatus (disclosed in, for example, US Patent No. 4 696 555), the mirror body to which the mirror is fixed is pivotably disposed in relation to a seat or receptacle formed on the surface of a drive unit casing disposed within the mirror housing and which includes two drive motors and a group of reduction gears. In such drive unit, a pair of internally threaded cylindrical screw rods is inserted into two openings, respectively, formed on two straight lines passing through the center of the seat formed on the drive unit casing and which are nearly perpendicular to each other, the screw rods being movable in a direction generally perpendicular to the surface of the drive unit casing but blocked against rotation. The end of each screw rod is connected, as blocked against rotation, to the seat formed on the rear side of the mirror body, and rotating shaft members having a pair of arm members provided with a pair of external thread portions in mesh with the internal threads, respectively, of the screw rods are rotatably supported around shafts formed on the bottom wall in the drive unit casing. Further, a hollow cylindrical gear member having on the outer cylindrical circumference thereof a gear in mesh with the last reduction gear among the drive reduction gears in group is disposed so as to rotate with the rotating shaft member, and the screw rods are housed in the hollow portions, respectively, of the gear members. In such mirror drive unit, the rotation of the motor is converted into a rotation of the gear member and the rotating shaft member through the reduction gear group, and further it is transmitted to the internal thread of the screw rod, in mesh with the external thread of the rotating shaft member. Since each of the screw rods is blocked against rotating, the screw rod itself are axially moved forwardly or backwardly depending upon the rotation direction of the motor. The substantial forward or backward movement of each screw rod causes the mirror body to slant around the horizontal or vertical axis pivoting around the center pivot. The outer circumference of each screw rod is in contact with the O-ring disposed within the drive unit casing and surrounding an opening formed in the drive unit casing, the internal thread form on the inner circumference of each screw rod is in mesh with the external thread formed on the ends of the arm members in pair formed on the top of the rotating shaft member, and a U-shaped spring is disposed between the arm members in pair and which always presses elastically the pair of external threads of the rotating shaft member to the internal threads of the screw rods. Since follows up with the pivoting movement around the center pivot of the mirror body within a predetermined angle, each of the screw rods is forcibly slanted with respect to the axial center in practice when it is moved forwardly or backwardly, so that the pair of arm members is forcibly deformed according to the slant of each screw rod while the external thread formed on the end of each arm member is kept in mesh with the external thread of each screw rod. The base of each rotating shaft member is rotatably supported around a shaft formed on the bottom wall inside the drive unit casing. The deformation of the arm members in pair causes the friction between the internal threads of the screw rods and the pair of external threads in mesh with the internal threads to increase, with the result that the motor for moving forwardly or backwardly each screw rod is applied with an extra load. From EP-A-0 265 973, a document which was published after the priority date of this invention, an adjusting device for a rear view mirror, comprising a drive unit, is known. This drive unit comprises supporting means for holding within a mirror housing a mirror body, having a mirror fixed thereon, said supporting means including a housing member fixed inside said mirror housing and means for pivotably supporting said mirror body. Two ball bases are mounted on the back side of said mirror body, one of which lies on a lateral pivot axis while the other lies on a longitudinal pivot axis, said lateral and longitudinal axes being perpendicular to each other. A pair of hollow cylindrical screw rods is provided, each being internally threaded on the inner wall thereof, provided at the end portion thereof with a ball portion which fits in a corresponding one of said ball bases, and axially movable through a cylindrical hole formed in said housing member while being unrotatable with respect to said housing member. Furthermore, there is provided a pair of rotation members rotatably mounted within said housing member, each composed of a shaft which is rotatably mounted within the housing member and is composed of a threaded cylindrical portion. Reduction gear means are connected with the gear formed on the rotation body of said rotation member to transmit a driving force to each of said rotation members and an electric motor drives said rotation member through said gear means. The object of the present invention is to overcome the above-mentioned drawbacks of the drive unit by providing a drive unit for an electric remote control mirror in which the forward or backward movement of a pair of screw rods is driven by motors, respectively, for slanting around horizontal and vertical axes a mirror pivotably supported by a pivot joint positively forced up with the pivoting of the mirror, each screw rod following up with the pivoting of the mirror for the axis to slant within a small predetermined angle. The above-indicated object can be achieved by providing a drive unit for an electric remote control mirror in which said rotation member is arranged so as to rotate with the circumference of the lower end of said cylinder rotation body being in contact with a receiving recess formed on the bottom of said housing member and each of said connection members is formed in a position away from the bottom wall of said housing member. Accordingly, the screw rod is smoothly moved forwards or backwards by preventing any extra load being applied to the motors. The subclaims contain preferred embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be better understood from the ensuing description made by way of example of the embodiments of the present invention with reference to the drawings in which: Figs. 1 through 4 show a first embodiment of the drive unit for an electric remote control mirror according to the present invention; Fig. 1 being a schematic diagram showing the entire electric remote control mirror, Fig. 2 being a sectional view of the essential portions of the drive unit, Fig. 3 being a sectional view of the drive unit, showing the rotation member in Fig. 2 rotated 90 degrees and Fig. 4 being a bottom view, enlarged in scale, of the rotation member; Fig. 5 is a sectional view of the essential portions of a variant of the connection members in the first embodiment; Figs. 6 through 10 show a second embodiment of the drive unit for an electric remote control mirror according to the present invention; Fig. 6 being a sectional view of the essential portions of the drive unit, Fig. 7 being a sectional view of the essential portions of the drive unit, showing the rotation member of the drive unit in Fig. 6 rotated 90 degrees, Fig. 8 being a perspective view, enlarged in scale, of the rotation member, Fig. 9 being a bottom view, enlarged in scale, of the rotation member, and Fig. 10 being a sectional view taken along the line X-X in Fig. 9; Figs. 11 and 12 shows a variant of the connection member composing the rotation member in the second embodiment and which is provided with a circular flute; Fig. 11 being a bottom view of the rotation member and Fig. 12 being a sectional view taken along the line XII-XII; Fig. 13 is a perspective view, enlarged in scale, of the rotation member, showing a variant of the protrusion in the second embodiment; and Figs. 14 and 15 are perspective views, respectively, enlarged in scale, of a variant of the rotation member in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to Figs. 1 through 4, showing a first embodiment of the drive unit for an electric remote control mirror. A mirror 10 fixed to a mirror body 12 is pivotably supported on a drive unit casing 14 disposed within a mirror housing (not shown) by means of a pivot joint 13. A pair of screw rods 16 (only one of them is shown for the simplicity of illustration) for slanting the mirror body 12 is inserted into the casing 14 through openings 18, respectively (only one of them is shown) formed in the casing 14, and the screw rods 16 are so arranged as to be driven by a pair of motors 20 (only one of them is shown). Each of these screw rods 16 is a hollow cylinder having a ball portion 22 formed at an end thereof, and has an internal thread 24 formed on the inner surface thereof. Each of the ball portions 22 is fitted in a spherical receptacle or seat 26 formed on the back of the mirror body 12. Actually, these spherical receptacles 26 lie on two straight lines passing through the center of the pivot joint in Fig. 1 and being perpendicular to each other, namely, on a vertical and horizontal axes, respectively. As the screw rod 16 shown is moved forwardly or backwardly in the direction of arrow A or B, the mirror body 12 is rotated in the direction of arrow a-b around the pivot joint 13, namely, it is slanted around the vertical axis. On the other hand, as the other screw rod 16 (not shown) is moved forwardly or backwardly, the mirror body 12 is slanted around the horizontal axis. In this embodiment, the central axis of the hollow cylinder composing each screw rod 16 goes not through the center of the ball portion 22 formed on the end of the screw rod 16, namely, the centeral axis of the hollow cylinder is offset from the center of the ball portion 22 as shown in Fig. 2, so that each ball portion 22 is blocked against rotation within each spherical receptacle or seat 26. The reference numeral 30 indicates a rotation member for transmission of the rotation of the motor 20 for each screw rod 16. The rotation member 30 comprises a shaft 36 having a screw thread 33 in mesh with the screw thread 24 on the inner surface of each screw rod 16 and also a pair of arms 34 spaced away from each other, a rotation body 38 formed like a hollow cylinder for holding therein the screw rod 16 and shaft 36 and having a spur gear 46 formed circumferentially integrally therewith on the outer circumference thereof, and a connection member 40 to connect the base of the shaft 36 and the rotation body 38 to each other. The rotation member 30 is disposed nearly coaxially with the screw rod 16, and received by a cylindrical receiving recess 42 formed on the base of the casing 14. That is, the outer circumference of the rotation body 38 is in light contact with the inner wall of the receiving recess 42 while the lower end of the hollow cylinder is in contact with the bottom wall of the receiving recess 42, and the rotation body 38 is rotatably supported in the receiving recess 42. The arms 34 formed at the end of the shaft 36 and forming a pair are disposed in a position offset 180 degrees from the axis of rotation of the rotation body 30, namely, the arms 34 are disposed opposite to each other. Further, a nearly U-shaped leaf spring 35 is disposed between the pair of arms 34. There are disposed small protrusions 35a at opposite positions oil the opposite arms of the leaf springs 35, and the protrusions 35a are fitted in the small holes 37 formed in the pair of arms 34. Owing to this arrangement, the external thread 33 on the arm end is pressed onto the internal thread 24 of the screw rod 16 while the leaf spring 35 does not come off the pair of arms 34. As shown in Fig. 4, a pair of sector-shaped relatively thin connection members 40 is disposed to provide a connection between the base of the shaft 36 and the inner surface of the rotation body 38. The rotation member 30 including the connection members 40 is integrally formed from a polyacetal resin. The thickness of the connection members 40 is selected to be thin as compared with the shaft 36 and rotation body 38 so that when applied with an external force, the shaft 36 is resiliently deformable, namely, it can be slanted with respect to the axis of rotation of the rotation member 30 following up with the rotation of the mirror base 12 around the pivot 13. In this embodiment, the thickness of the connection members 40 is selected to be about 0.7 mm thick, the wall thickness of the shaft 36 is about 1.5 mm thick, and the wall thickness of the rotation body 38 is about 1.1 mm. The pair of connection members 40 is disposed in positions offset away from the pair of arms 34, namely, in such positions as perpendicular to each other as shown in Fig. 4, so that the shaft 36 is easy to be slanted in a direction in which the pair of arms 34 is connected to each other, rather than in a direction in which the pair of connection members 40 is connected to each other. The spur gear 46 formed circumferentially on the outer circumference of the rotation body 38 is coupled to a worm 50 fixed on the output shaft of the motor 20 through a reduction double-geared spur gear 52. The forward or reverse rotation of the motor 20 is converted into a rotation of the rotation body 38 by means of the reduction double-geared spur gear 52 and further into a final forward or backward movement of the screw rod 16. At this time, the screw rod 16 is axially slanted through a small predetermined angle following up with the pivoting of the mirror body 12 while moving forwardly or backwardly. However, as the pair of connection members 40 connecting the rotation body 38 and shaft 36 is resiliently deformed so that the shaft 36 is slanted around near the center of the base thereof in response to the slanting of the screw rod 16, the external thread 33 formed on the arm 34 and which is in mesh with the internal thread 24 formed on the inner surface of the screw rod 16 is not applied with any excessive load and thus the motor is not applied with any excessive load. In this embodiment, the pair of sector-shaped connection members 40 connect the base of the shaft 36 and the inner surface of the rotation body 38 to each other. However, the shape and number of these connection members 40 are not limited to those in this embodiment, but the connection members 40 may be of such a resiliently deformable structure that the shaft 36 can be slanted following up with the rotation of the mirror base 12 around the pivot 13. The reference numeral 60 indicates an O-ring disposed within a circular recess formed in the inner wall of the opening 18 and which is in contact with the outer circumference of the screw rod 16 to prevent any dust or a liquid like water from coming into the inside of the casing 14 while ensuring a smooth forward/backward movement of the screw rod 16. Fig. 5 shows a modification of the connection member 40 in the first embodiment. As shown, the pair of connection members 40 has a flute 41 formed circumferentially thereon to improve the resilience of the connection members 40. That is, in the first embodiment, the pair of connection members 40 are disposed in positions offset from the pair of arms 34, so that the shaft 36 is easily slanted in a direction in which the arms 36 in pair are connected to each other, rather than in a direction in which the connection members 40 in pair are connected to each other. It will be obvious that the provision of such circular flute 41 facilitates the shaft 36 to slant also in the direction in which the connection members 40 are connected to each other. Actually, since the radial length of the connection members 40 is designed 3 to 5 mm, one such flute 41 will do. However, more than one such flute 41 may be provided concentrically. That is, the pair of connection members 40 may be formed into aneroid diaphragm-shaped flat members. Figs. 6 to 10 show a second embodiment of the drive unit for an electric remote control mirror. The same elements as those in the first embodiment are indicated with same reference numerals also in this second embodiment. In the second embodiment, the lower end of the shaft 36 and that of the rotation body 38 are connected to each other by a pair of connection members 40 extending in a direction X-X, and also there is formed at the lower end of the rotation body 38 a pair of protrusions 84 extending in a direction parallel to the shaft 36. The pair of protrusions 84 is diametrically disposed as shown in Fig. 8 and in positions 90 degrees offset from the pair of connection members 40, namely, in a line indicated with an arrow Y-Y. Each of the protrusions 84 in pair is formed from a portion of the outer circumference of the rotation body 38 which is extended parallelly with the shaft 36. The end of each protrusion 84 is formed to have a curved surface of a predetermined curvature and is in contact with the inside bottom face of the casing 14. The provision of such protrusions 84 in pair enables the swinging of the rotation body 38 which takes the direction of arrow Y-Y as axis of swing, and provides a gap of a predetermined distance between the connection member 40 and the inside bottom face. The rotation member 30 thus formed is rotated as driven by the motor 20 by means of the reduction gear group 52 with the end of the protrusions 84 in pair being in contact with the inside bottom face of the casing 14, namely, as substantially supported on two diametrical points. Since the pair of connection members 40 and the pair of protrusions 84 are located offset from each other, when the shaft is applied with a force from the screw rod 16, the pair of connection members 40 are twisted and/or the entire rotation body 38 can swing around the Y-X axis taking as fulcrum the pair of protrusions 84, whereby the shaft 36 can axially slant while rotating, so that it can positively follow up with the pivoting of the mirror body 12. In the first embodiment having been described previously, the shaft 36 is easily slanted in a direction in which the arms 34 in pair are connected to each other, rather than in a direction in which the connection members 40 in pair are connected to each other, but it will be obvious that in the second embodiment, since the entire rotation body 36 can swing owing to the pair of protrusions 84, the shaft 36, when applied with a force from the screw rod 16, is easily slanted in a direction in which the connection members 40 in pair are connected to each other. Also in this embodiment, there is formed on the inside bottom face of the casing 14 opposite to the base of the shaft 36 a truncated-control protrusion 86 extending axially as shown in Fig. 7. When the shaft 36 is applied with an axial downward force from the screw rod 16, the protrusion 86 limits the descending distance of the shaft 36 to within the range of resilient deformation of the connection member 40. That is, the length of the pair of protrusions 84 composing the fulcrum of swing and the height of the truncated-conical protrusion 86 from the inside bottom face of the casing 14 should be set so that the shaft 36 can move axially downward within a range of the resilient deformation of the connection member 40. Thus, even when applied with any excessive force from the screw rod 16, the shaft 36 is in contact, at the base thereof, with the truncated-conical protrusion 86, whereby the shaft 36 will not go down any more beyond a predetermined distance so that the connection member 40 will not be broken. Figs. 11 and 12 show a variant of the rotation member 30 in the second embodiment. The pair of sector-shaped connection members 40 composing the rotation member 30 has circumferentially formed at a portion thereof a circular flute 91 which facilitates the slanting of the shaft 36 in the direction in which the connection members 40 in pair are connected to each other. The flute 91 is not limited to a single one but more than one flute may be provided concentrically. Fig. 13 shows a variant of the pair of protrusions formed at the lower end of the rotation body 38. In this variant, the protrusion is indicated with a reference number 94, and has the end thereof formed smooth and flat. The protrusion 94 thus formed has a large area of contact with the inside bottom face of the casing 14 as compared with the protrusion 84 having a curved end face as in the second embodiment. Being smooth and flat, the end of the protrusion 94 will not be any hindrance to the rotation of the rotation member 30 and substantially permits the rotation member 30 to swing. Fig. 14 shows a variant of the connection member 40 in the second embodiment. In this variant, the connection members 40 are not made in pair but three in number. They are indicated with reference numbers 100a, 100b and 100c, respectively. The connection members 100a, 100b and 100c are formed with an angle of about 120 degrees around the shaft 36, and located offset from both the protrusions 84 in pair. The larger the sector area of each of these connection members 100a, 100b and 100c, the higher their mechanical strength is. It is of course that the sector area should be set so that the connection members are resiliently deformable. Fig. 15 shows a variant of the connection member 40 of the rotation member 40 shown in Fig. 13. It is substantially equivalent to the rotation member 30 shown in Fig. 14, so it will not be explained any further.

Claims: A drive unit for an electric remote control mirror (10), comprising: supporting means for holding within a mirror housing a mirror body (12) having a mirror (10) fixed thereon, said supporting means including a housing member fixed inside said mirror housing and means for pivotably supporting said mirror body (12): two ball bases (26) mounted on the back side of said mirror body (12), one of which lies on a lateral pivot axis while the other lies on a longitudinal pivot axis, said lateral and longitudinal axes being perpendicular to each other; a pair of hollow cylindrical screw rods (16), each being internally threaded on the inner wall thereof, provided at the end portion thereof with a ball portion (22) which fits in a corresponding one of said ball bases (26), and axially movable through a cylindrical hole formed in said housing member while being unrotatable with respect to said housing member; a pair of rotation members (30) rotatably mounted within said housing member, each composed of a shaft (36) provided with at least two arm members (34) having plural screw threads (33) coupled to the screw threads (24) of each of said screw rods (16) and which are spaced apart from each other, a hollow cylindrical rotation body (38) holding therein said screw rod (16) and shaft (36) and having a gear (46) integrally formed therewith on the outer circumference thereof, and a plurality of radially extending connection members (40) to provide a connection between said shaft (36) and rotation body and which is formed relatively thin so as to resiliently be deformable; reduction gear means (52) connected with the gear (46) formed on the rotation body of said rotation member (30) to transmit a driving force to each of said rotation members (30); and an electric motor (20) for driving said rotation member (30) through said gear means (52), wherein said rotation member (30) is so arranged as to rotate with the circumference of the lower end of said cylindrical rotation body (38) being in contact with a receiving recess (42) formed on the bottom of said housing member and each of said connection members (40) is formed in a position away from the bottom wall of said housing member. The drive unit for an electric remote control mirror according to claim 1, wherein said rotation member (30) is so arranged as to rotate with the whole circumference of the lower end of said cylindrical rotation body (38). The drive unit for an electric remote control mirror according to claim 1, wherein said cylindrical rotation body (38) of said rotation member (30) is provided at diametrical positions on the circumference of the lower end thereof, which correspond to said pair of arm members (34), with a pair of protrusions (84) extending parallelly with said axial direction and which are in contact with the bottom of said receiving recess (42), so that said rotation body (38) can swing around a straight line connecting said pair of protrusions (84). The drive unit for an electric remote control mirror according to one of claims 1 to 3, wherein said plurality of connection members (40) are disposed in positions offset from said pair of arm members (34). The drive unit for an electric remote control mirror according to claim 3, wherein there is provided on the bottom wall of said housing member in a position opposing the base portion of said shaft (36) of said rotation member a stopper (86) which limits the axial movement of said shaft (36). The drive unit for an electric remote control mirror according to claim 4, wherein said protrusions (84) are formed to have a substantially same curvature as that of the outer circumference of said cylindrical rotation body and are rounded at the ends thereof. The drive unit for an electric remote control mirror according to one of claims 1 to 4, wherein each of said connection members (40) has at least a flute (41,91) formed circumferentially thereon.

Inventors: YOSHIDA, NORIO
Applicants: ICHIKOH INDUSTRIES LIMITED
Application year: 1988
Main classification: B60R1
IPC codes: B60R1