KEYLESS STEERING-SHAFT LOCK

Abstract: In the lock a locking bar (18) is operated by an electric motor (22) by way of reduction gearing (23) and a rotator (21). The reduction gearing (23) includes a central externally toothed input gear (40) fixedly mounted on the output shaft (22a) of the motor (22). A plurality of intermediate planetary pinions (41) are mounted around the input gear (40) and mesh therewith, central shafts (44) of these pinions (41) being arranged to make a common planetary motion along an imaginary circle concentric with the output shaft (22a) of the motor (22). A first internal gear (42) is stationary-­ mounted and mesh with the planetary pinions (41) whilst a second internal gear (43) which is rotatably-mounted also meshes again with the planetary pinions (41). The number of teeth on the second internal gear (43) is slightly larger than on the first internal gear (42). Preferably one of these two internal gears (42, 43) has profile-shifted teeth.

Description: KEYLESS STEERING-SHAFT LOCK This invention relates generally to a keyless steering-shaft lock. More specifically, it relates to an improved keyless steering-shaft,look wherein a sbaft-locking and unlocking bar is operated by an electric motor by way of reduction gearing and a rotator. Most conventional steering looks have been designed as mechanical locks which are key-operated for on-off operation of the look. More recently, however, keylesa steering locks have been developed. With one or these, an operator actuates a plurality or specifically selected button switches one after another so as to automatically unlock the look and make the steering shaft operable at the wish of the operator. The looking and un- locking bar is ariven by an electric motor by way of reduction gearing and a rotator, the latter having a cam section for actuation of the bar in the desired sense, that is, either in the shaft locking or un-locklag direction, as the case may be. It is common practice to mount such a keyless steering-shaft lock at substantially the same position of the steering column as the conventional Therefore, the overall size or the locking arrangement must be minimised to avoid physical contact by the vehicle driver and maintain the freedom of movement or the latter. The electric motor for driving the locking bar between its locking and unlocking positions must have the smallest possiule external dimensions Ci.e. ue a miniature motive power unit). Dn the other hand, the motor must have a sufficiently high speed to consistently transmit enough rotational torque to the rotator which causes the shaft-locking oar to move between its locking and unlocking position. To accomplish this transmission, however, the reduction gearing arranged between the motor and the rotator must have larger external dimensions which may substantially hinder the desired freedom of movement or the driver. It is thererore an obJect of the present Invention to provide an Improved keyless steering shaft lock having reduction gearing of suostantially reduced external dimensions out without impaired power delivery performance. Tbis or eft is achieved in accordance with the invention in a keyless steering-shait lock of the type mentioned at the beginning whereof in that the reduction gearing comprises a central externally toothed input gear fixedly mounted on an output shaft of the motor, a plurality of intermediate planetary pinions mounted around the input gear and meshing therewith, central shafts of these piaiona being arranged to make a common planetary motion along an imaginary circle concentric with the output shaft or the motor, a first stationarymounted internal gear meshing with the planetary pinions, and a second rotatably-mounted internal gear also meshing with the planetary pinions, the number of teeth on the second internal gear being slightly larger than on the first internal gear. Either one of these two internal gears preferably has profile-shirted teeth. The invention will be desoribed further, by way or example, with reverence to the accompanying drawings1 in which: Fig. 1 is a sectional elevation of a preferred embodiment of the steering lock or the invention; Fig. 2 is a top plan view of the steering lock shown in Fig. 1 wherein a top lid cover has been omitted for clearer illustration of the inside arrangement; Fig. 3 is an enlarged sectional view of a bearing arrangement for the steering shaft in the steering lock shown in Figs. 1 and 2; Fig. 4 is a slightly enlarged section taken along the sectlon line A-A' shown in Fig. 2; and Flg. 5 is an end view of the rotator in the steering lock shown in Figs. 1 to 4. As illustrated in Pigs. 1 and 3 of the drawings, a conventional steering shaft 10 is rotatably supported by a ball bearing unit 12 which is mounted in a housing 13 of a preferred embodiment of the steering lock of the invention. This housing 13 is formed with a hollow cylindrical portion 14 in which the bearing unit 12 is mounted, for example, by a pressure fit. In the upper part of the housing 13, a guide opening 1'/ is formed which is in communication with the hollow cylindrical space 14 and with container chambers 15. The upper part of the housing 13 is tlghtly and rigidly closed by a push-f it closure lid 16 which helps to prevent theft, A locking bar 18 is slidably mounted on the guide opening 17, the bar Deing shown in Pig. 1 in its advanced locking position in engagement with a reception recess 11 formed in the steering shaft 10. A so-called "hanger member" 19 slides in unison with the locking bar 18. The bar 18 and the hanger member are usually fixed together. @ coil spring 20 is mounted under compression between the lid 16 and the hanger member 19 and thus urges the bar 18 to move downwards in Pig. 1 towards the locking position. A member 21 called "a rotator is kept in pressure contact with the hanger member 19. This rotator 21, the end of which is shown in Pig. 7, gcts to prevent excess advancement of the par 18. An electric motor 22, a gearing unit 23 and and output shaft wheel 36 are mounted ln the housing 13 as shown in Fig. 1. Rotation is transmitted from the motor 22 through the gearing unit 23 to the output shaft wheel 36. The gearlng unit 23 is houses in a casing a4, the cross-section or which is shown in Fig. 4. The gearing untt 23 includes a central, exterrally tpothed input gear 40 rixealy mounted on the output shart 22a of the motor 22. Mountea around the input gear 40 and meshed therewith there are a plurality or lntermedlate planetary pinions 41, each having a central shalt 44. These pinion shafts 44 are arranged to perform a planetary motion along an imaginary circle concentric with the motor output shart 22a. A first stationary- mountea internal gear 42 meshes with the planetary pinions 41 and a second rotatably-mounted internal gear 43, which has a slightly larger number of teeth than.the first gear 42, also meshes with the planetary pinions 41. The second internal gear 43 is formed by a part of the output shaft wheel 36 which is mechan ically coupled to the rotator 21, which in turn mechanically controls the position of the bar 18. The stationary internal gear 42 is integral with the housing 13. The planetary opinions 41 are prererably arranged in diametrically opposing pairs, te shafts 44 of these opinions 41 preferably being rotatably supported on a common bearing ring *5. One of the internal gears 42, or 43 are preferably of the prorile-shirted type. In the casing 24 two diametrically opposite openings 27 and 28 are provided ror housing respective contactless lead switches 34 and 3, as shown in Fig. 4. The former switch 34 is adapted for sensing the shaft-unlock position, while the latter switch 35 senses the shaft-lock position. Then the motor 22 is energized to rotate, output torque is transmitted therefrom through the reduction gearing 23, the output shaft wheel 36, a mech animal coupling 200 provided between the latter and the rotator 21 and by way of the rotator 21 and the hanger member 19 to the locking bar 18 so as to raise the latter from Lts locking position shown in Fig. 1 towards its unlocking upper position. As shown in Fig. 5, the end of the rotator 21 is formed with a sector cam 29 having a cam angle alpha (R ) of approximately 15 to 150 degrees, most preferably about 90 degrees. The cam angle is measured between respective slide slopes 31 and 32 around a slightly rounded apex 30. During the shaft-looking stage, the switch 35 is located nearest to a shaft-position indicator magnet 25 embedded in the output shaft wheel 36 so it is energized. At the same time, the other switch 34 is positioned remotest from the same magnet 25, so that switch 34 is de-energized. Then a certain switch, not shown, is turned on, the motor 22 is rotated. Motion is transmitted therefrom through the reduction gearing 23, the output shaft wheel 36 and the coupling 200 to the rotator 21 and thence to the hanger member 19 fixedly attached to the loosing bar 18, so as to raise the latter in Fig. 1 towards its unlocking position. s the bar 18 moves towards its unlocking position the magnet 25 is brought towards its position adjacent the switch 34, so as to sense the unlocking position and to de-energize the motor 22 by opening the on-off switch, not shown, for the latter. In this way, the precise looking and unlocking operations can be assured. In place of the aforementioned lead switches 34, 35, microswitches may be used if desired. A numerical example of the main constituting elements or the reduction gearing 23, together with the general mathematlcal relationship governlng them is shown herelaunderz Gears Symbol of the Practical number of teeth number of teeth Input gear 40 Za 10 Planetary opinions 41 Zb 15 Stationary internal gear 42 Z@ 40 Output internal gear 43 Zd 42 Then expressing the respective numbers of revolutions of the input gear 40 and the output gear 43 by na and nb' respectively, then: EMI10.1 To obtain an example of the results, the rore- golng practical numbers of teeth are introduced into the foregoing formula. We then obtain: nb/na=1/105 This numerical result indicates that the effects or the above-aeseribea reduction gearing 23 are superior. The external dimensions thereor are compact yet a large reduction ratio may be obtained In order that both the stationary internal gear 42 anu the rotatable internal output gear 43 are able to co-operate with the planetary pinlone 41, one of these is preferably or the pror1e-shi1ted type and the numuer OI teeth on the rotatable output internal gear 43 is elightly larger tnan on tne stationary maternal gear 42. It will be clear from the foregoing that by adopting the specifically designed superior reduction gearing according to the invention, the motor 22 and the reduction gearing 23 may have the smallest possible external dimensions without sacrificing the desired high torque delivery performance in the motor-driven, slide bar type steering shaft lock arrangement.

Claims: CLAIMS: 1. A keyless steer mg-shaft lock wherein a locking bar (18) is operatea by an electric motor (22) by way of reduction gearing (23) and a rotator (21), characterised in that the reduction gearing (23) comprises a central externally toothed input gear (40) fixedly mounted on an output shaft (22a) of the motor (22), a plurality of intermediate planet ary pinions (41) mounted around the input gear (40) and meshing therewith, central shaft (44) of these opinions (41) being arranged to make a common planetary motion along an imaginary circle concentric with the output shaft (22a) of the motor (22), a first stationary-mounted internal gear 42 meshing with the planetary pinions (41), and a second rotatably-mounted internal gear (43) also meshing with the planetary pinions (41), the number of teeth on the second internal gear (42) being slightly larger than on the first internal gear (42). 2. A keyless steering shaft lock as claimed in Claim 1, wherein either one of the two internal gears (42, 43) has profile-shifted gear teeth.

Inventors: SATO, HIDEKAZU
Applicants: KOKUSAN KINZOKU KOGYO KABUSHIKI KAISHA
Application year: 1984
Main classification: B60R25
IPC codes: B60R25