AU598083B2 - Reclining angle adjustment device - Google Patents

Description

i. 598083 S F Ref: 47148 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPEC!FICATION

(ORIGINAL)

FOR OFFICE USE; Class Int Class This document contains tl11i amnendments made undcr Section 49 and is correct f-r printing.

Complete Specification Lodged: Accepted: Pub! shed Priori ty: Related Art: II Name and Address of Applicant: Address for Service: ShiroJi Kinzoku Kogyo Kabushiki Kaisha 2 Kirlhara-cho Fujisawa-shi Kanagawa-kon 252

JAPAN

Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention entitled: Reclining Angle Adjustment Device The following statement Is a ftll description of this invention, including the best method of performing it known to me/us 5845/3 RECLINING ANGLE ADJUSTMENT DEVICE BACKGROUND OF THE fNVENTION The present invention relates to a reclining angle adjustment device for adjusting the angle of inclina tion of the seat back of a recli ning seat in a motor vehicle, the reclining angle of the reclining seat.

There are known reclining angle adjustment devices in which the reclining angle is adjusted by means of a planetary gear mechanism.

The planetary gear mechanism employed in the reclining angle adjustment device is composed of a first arm having an external gear, a second a-m having an internal gear with more gears than those of the external gear, and a shaft having a concentric portion inserted through the center of the external gear and an eccentric portion inserted through the conteLe of the internal gear.

The exter'nal and internal gears are held in mesh with each other throxugh the shaft. When the shait is rotated about its own axis, the angle of the first arm with respect to the second arm is varied. Therefore, by attaching one of the first and second arms to the frame of the seat back of a seat and the other arm to the frame of the seat cushion thereof, the reclining angle of the seat can be adjusted by rotating t[,e shaft.

The first arm, the second arm, and the shaft Lizo machined so that they mesh without biting into each other 2 irrespective of machining tolerances. Therefore, there are always gaps or backlashes between fitting and meshing members of the first arm, the second arm, and the shaft. These gaps or backlashes result in unwanted motion of the seat back with respect to the seat cushion, making the person on the seat uncomfortable and producing noise. While the motor vehicle is running, the first arm may vibrate with respect to the second arm due to vibration of the motor vehicle, and the shaft may temporarily become free to rotate of its own accord about its own axis, so that the second arm and hence the seat back may be tilted even when no angle adjustment is made for the seat back. The discomfort which the person on the seat may suffer, the noise produced by the seat back, and the accidental rotatation of the shaft tend to increase with increased gaps due to localized machining tolerances of the members.

SUMMARY OF THE INVENTION It is the object of the present Invention to overcome or substantially ameliorate the above disadvantages, There is disclosed herein a reclining angle adjustment drkvice for a o o, seat, comprising: a shaft having a concentric portion and an eccentric portion and o,.0 rotatable for adjusting the reclining angle of the seat; Sa tapered bushing having a tapered inner peripheral surface S• d engaging in said eccentric portion of the shaft; CA", a gear train including an external gear and an internal gear meshing with said external gear, said internal gear having more teeth than said external gear, a first arm having one of said external and internal gears, said one of the external and internal gears being rotatably fitted at its center o o" over said concentric portion; a second arm having the other of said external and internal 3) gears, said other of the external and internal gears being rotatably fitted at its center over said tapered bushing; and a resilient member engaging said tapered bushing for normally pressing the tapered bushing axially of said shaft In a direction to strengthen meshing engagement between said external and internal gears.

-3- BRIEF DESCRIPTION OF THE DRAWINGS A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings, wherein: Fig. 1 is a side elevational view of a reclining angle adjustment device according to the present invention; Fig, 2 is a cross-sectional view taken along line II II of' Fig, 1; Fig. 3 Is a view showing the positional relationship between an external gear, an Internal gear, and a shaft of the reclining anglih adjustment device; and Fig. 4 is an exploded perspective view of the reclining angle adjustment device.

DETAILED DESCRIPTION OF THE EMBODIMENT As shown in Figs. 1 and 2, a reclining angle adjustment device according to the present invention Includes a lower arm (first arm) 1 fixed to the seat cushion frame (not shown) on a reclining seat, and an upper arm (second arm) 2 fixed to the seat back frame (not shown) rf the reclining seat. As illustrated in Fig, 2, the lower and upper arms 1, 2 have external and internal gears la, 2a, respectively, embossed on sides thereof as by precision pressing. The number of teeth of the internal gear 2a is ZO selected to be at least one larger than the number of the teeth of the external gear 3a, A cover 4 is secured to the said of the lower arm 1 facing the upper arm 2 by means of a rivet 3. As shown in Figs, 2 and 4, a shaft 5 has axially spaced concentric portions 5a, 5b and a tapered eccentric portion 5c disposed between the concentric portions 5a, 5b, The concentric portion 5a is fitted in a hole- 1b defined ii c(-7,trally in the external gear la of the lower arm 1 wheras the concentric portion 5b is fitted in a hole 4a defined in the cover 4. A, tapered bushing 7 having a conical tapered inner surface is fitted over the eccentric portion 5c which has a conical pered outer surface. The tapered bushing 7 is fitted in hole 2b defined centrally in the internal gear 2a.

The upper arm 2 and the lower arm 1 are rotatably mounted respectively on the eccentric portion 5c (tapered to bushiiig 7) and the concentric portion 5a of the shaft The externpi gear ila and the internal gear 2a are held in mesh with each other. The lower arm 1, the upper arm 2, and the shaft )ointly constitute a gear train mechanism.

The cover 4 has an annular ridge 4b on its surfa(,ce facing the upper arm 2, the annular ridge 4b abutting against the upper arm 2. The shaft has an annular groove 5d defined in one end thereof, and a retaining ring 6 is fitted in the groove 5d to hold the cover 4 on the shaft 5. h\ means for rotating the shaft C, such as an angle adjusting handle, not shown, is mounted on the other end of the shaft so that the shaft 5 can be rotated about its own axis by the handle. A\ circular plate-like resilient member 8 is disposed under compression between the upper arm 2 and the cover 4. The resilient member 8 is held against the tapered bushing 7 and the cover 4 for -normally pressing the tapered bushing 7 toward the lower arm I, i.e.f to the lef~t in FIG. 2 in the axial.

direction of the shaft Operation of the reclining angle adjustment device thus constructed will be described below. When the shaft 5 is rotated, the upper arm 2 is turned at a certain speed reduction ratio by the gear train mechanism to adjust the angle oi the seat back. The tapered bushing 7 is normally pressed toward the lower arm 1 under the resilient force from the resilient member 8. As shown in FIG. 3, the distance D 1 between the inner peripheral surface of the to hole 2b of the upper arm 2 and the outer peripheral surface of the eccentric portion 5c in the direction (referred to as the "eccentric direction") in which t'he eccentric portion Sc is displhced of~f center is smaller than the H distance 02 therebetween in the direction diametrically opposite to the eccentric direction 02), so that the tapered bushing 7 serves as a wedge at a position P in FIG.

3 or in the eccentric direction. Since the bushing 7 serves as a wedge, the upper arm 2 is urged in a directk on to strengthen the meshing engagement between the internal and exte--nal gears 2a, la, in the eccentric direction under the bias of the resilient member 8, Therefore, the U meshing region t) of the internal and external gears 2a, la is free of backlash. The concentric portion 5a of the shaft 5 is held against an inner peripheral surface of the hole lb, and the concentric portion 5b is held against an inner peripheral surface of the hole 4a.

with the arrangement, of the present invention,

P.-

the shaft 5 and the inner peripheral surfaces of the holes lb, 4a which engage the shaft 5 are pressed against each other under the resilient force of the resilient member 8 applied through the wedging tapered bushing 7. Moreover, the internal and external gears 2a, la are forced into mesh with each in the meshing region D under the resilient force of the resilient member 8 applied through the wedging tapered bushing 7. Therefore, no backlash is present between these engaging members, and lhe person on the seat will not be made uncomfortable and no noise will be produced by backlashes which would otherwise exist. Even when the seat is subjected to vibration while the vehicle is running, the upper arm 2 is prevented from becoming temporarily free from the lower arm 1 to allow the upper arm 2 and hence the seat back to turn or be tilted without V* any angle ad-i~stment.

The external gear may be on the upper arm and the internal gear may be on the lower arm, and the eccentric portion of the shaft may be rotabably disposed in the external gear and the concentric portion may be rotatably disposed in the internal gear.

Although a certain preferred embodiment has been shown and described, it should be understood that many changes and modifications may b made therein without departing from the scope of the appended claims.

i f" u

Claims (4)

1. A reclining angle adjustment device for a seat, comprising: a shaft having a concentric portion and an eccentric portion and rotatable for adjusting the reclining angle of the seat; I a tapered bushing having a tapered inner peripheral surface engaging in said eccentric portion of the shaft; a gear train including an external gear and an internal gear meshing with said external gear, said internal gear having more teeth than said external gear; i a first arm having one of said external and internal gears, said I one of the external and internal gears being rotatably fitted at its c nter over said concentric portion; a second arm having the other of said external and internal Sgears, said other of the external and internal gears being rotatably fitted at its center over said tapered bushing; and a resilient member engaging said tapered bushing for normally ipressing the tapered bushing axially of said shaft in a direction to strengthen meshing engagement between said external and internal gears. i

2. A reclining angle adjustment device according to claim 1, wherein said external gear is embossed on said first arm, said internal i gear is embossed on said second arm, further including a cover cooperating H with said first arm in sandwiching said second arm therebetween, said resilient member being disposed between said cover and said second arm for Spressing said tapered bushing.

3. A reclining angle adjustment device according to claim 2, wherein said resilient member comprises a circular plate through which said shaft extends.

4. A reclining angle adjustment device substantially as hereinbefore described with reference to the accompanying drawings. DATED this TWENTIETH day of MARCH 1990 Shiroki Kinzoku Kogyo Kabushikl Kalsha Patent Attorneys for the Applicant SPRUSON FERGUSON