Articulation device of reclinable seat backs

Abstract: An articulation device of reclinable seat backs is made of a seating (12) having an outline consisting of two main opposite substantially rectilinear sections (13 and 26) converging towards jointing sections which are also rectilinear and step-like to one another (23, 24, 25); the other extreme of one of the main sections (13) is jointed to an arched section (32), whilst the other extreme of the other main section (26) is jointed to substatially rectilinear sections (27, 28) which are step-like to one another; the arched section (32) and the extreme one of the rectilinear sections (28) jointed to the main sections (13, 26) are joined to one another by means of a substantially U-shaped section (30); a cam has an outline consisting of two main opposite sections (13′, 26′) so as to copy the corresponding sections (13, 26) of the seating (12), one in the locking position and one in the releasing position of the seat back; the main sections of the cam are converging at one extreme towards a rectilinear jointing section (23′) corresponding to those (23, 24, 25) of the seating (12); the other extremes of the main sections of the cam are jointed through a bent section (32′), at least a rectilinear section (28′) and a substantially U-shaped section (30′) corresponding to the similar ones of the seating (12).

Description: The invention regards an articulation device of reclinable seat backs. Several devices for the adjustment of the inclination of a seat back are available at present. Some of them consist in a cam engaging into a suitable seating of the seat, a sector gear integral to said cam is appointed to be engaged in a corresponding sector gear of the seat back during releasing stage of said back. A crank defines locking and releasing conditions respectively by rotating the cam in its seating which is conformed to drive said cam to vertical movement during its rotation. The French patent application FR-A-2 377 175 illustrates an articulation device of a reclinable seat back comprising a first plate integral to the cushion carrying a first true sector gear on an horizontal crosswise axis, and a second plate integral to the back carrying a second true sector gear on a second horizontal crosswise axis, parallel to the one of the first sector gear; said second sector gear is able to engage into the first sector gear when the respective axes are coinciding; a true opening on the axis of the respective sector gear is obtained in the plate integral to the cushion; a rotary cam carrying the plate of the back in its movement, is fitted in said opening and set to rotate by means of a crank, that can be operated by the person sitting on the seat, to rotate the cam between two extreme positions into the opening, respectively locking and releasing the seat back as the axes of the sector gears are coinciding and moving away; elastic means acting on the cam and on the crank to drive to the reciprocal engagement of the two sector gears are also assembled. The Italian Utility Model No. 53294 B/87 of May 6, 1987 indicates, furthermore, that both the cam and the opening where it is fitted have an outline consisting of a plurality of bent and rectilinear sections abreast, the points of which are substantially equidistant from the respective centers for 270 degrees angular extension of the respective outlines; the remaining angular extension of the cam consists of a section extending in a substantially tangential direction from an extreme of the preceding outline part and turns over angularly to joint with substantially rectilinear section extending in substantially radial direction from the other extreme of the preceding part; the remaining angular extension of the seating is formed by a first step-like section, extending from an extreme of the preceding outline part followed by an arched section jointing with a substantially rectilinear section extending in substantially radial direction from the other extreme of the preceding part. The device described in Patent Application FR-A-2 377 175 (corresponding to the preamble of claim 1) requires a cam and a pertinent seating realized by very accurate surface processing to ensure reliability in every type of employment and long repeated employment as only high precision couplings of cam-seating give a correct operation of the device. On the contrary, the device described in the above-mentioned Italian Utility Model No. 53294 B/87 has extremely complex cam and seating outlines which cannot easily be processed and which may give reliability problems with time. Purpose of this invention is to propose an easy to realize cam adjustment device where the cam and the pertinent seating do not require expensive and toilsome surface processing. Purpose of this invention is also to propose a cam adjustment device, highly reliable in time, and having also a safety area corresponding to a first section of cam rotation avoiding disengagements of the system caused by any type of external forces acting on the seat back. For these purposes and further ones which will be better appreciated as the description follows, the invention proposes an articulation device for reclinable seat backs according to claim 1. The device of the invention will now be described with reference to the attached drawings, as follows: Fig. 1 is the side view of an articulation of a seat - the position of the back is locked; Fig. 2 is a view like Fig. 1: the dash-and-dot line represents the position of released seat back; Fig. 3 is the exploded view of the main elements forming the device, as illustrated in Fig. 1 and 2; Fig. 4 and 5 are front views of the outlines of two elements forming the device; Fig. 6 is the view of the two elements of Fig. 4 and 5 coupled in two opposite operating stages; Fig. 7 is the diagram of the forces and centers of rotation of the unit of Fig. 6. Plate 10 is integral to the seat cushion whilst plate 11 is integral to the back of the seat. A slot 12 is obtained in plate 10 (see also Fig. 4) the outline of which consists of a first substantially rectilinear section 13, followed by three substantially rectilinear sections 23, 24 and 25. The end of this latter section joints to a further substantially rectilinear one 26. Said section 26 is joined to two rectilinear sections 27 and 28, the latter is joined to a rectilinear section 30 by means of an S-shaped section 29; section 30 finally is joined to the bent end 32 of the rectilinear section 13 by means of a further S-shaped section 31. In said seating 12 the central half-blank cam-like part 17 of a disc 18 is inserted. Said central part 17 (see also Fig. 5) has a round appendix drilled in the interior and splined 19 into which a splined bushing of a crank 21 is inserted through hole 22 of the plate 11. On the contrary, the outline of the cam 17 is coupled with plate 11 equipped with hole 22 for such purpose. The outline of the cam 17 consists of bent and rectilinear sections as seating 12 and for this reason the sections of the cam corresponding to those of the seating bear the same reference numbers followed by an apex. The only exception is the fact that the rectilinear sections 26′ and 13′ of cam 17 are joined through section 23′ only in opposition to the seat having three joining sections 23, 24 and 25 joined to one another. Finally, the plate 10 carries toothings 30 appointed to engage in corresponding toothings 31 of the plate 11 in the locking position of the seat back to the cushion. In the locking condition as illustrated in Fig. 1 the cam is housed in the seating 12 and is stretched by a first spring 82 with its section 26′ against the corresponding section 26 of the seating, and at the bottom its section 28′ against section 28 of the seating (see also Fig. 6 where cam 17 is illustrated in released position); this determines the lowered position at lower limit stop of axis A of cam rotation and subsequent reciprocal engagement of sector gears 80 and 81, so that the seat back is locked in the illustrated position. If the release is desired, rotate the crank 21 - as in dash-and-dot line of Fig. 2 - opposing first spring 82, so that the cam 17 rotates around its own axis hoisting itself whilst its projection 30′ slides on outline 30 of the seating 12 until it reaches the position of Fig. 2 and 6 (dash-and-dot line), where the axis of the cam is being carried in the hoisted B position and cam 17 is fixed with surfaces 13′ and 32′ against surfaces 13 and 32 of the seating 12 and with the part between section 29′ and projection 30′ against angular section 29 of the seating 12. As cam 17 is being hoisted, the sector gear 80 carried by it is also hoisted disengaging itself from sector gear 81 of the seat back, opposing a second spring 83, which can thus rotate and take the desired inclination. The described release position always takes place in opposition to said first spring 82 connected between cam 17 and plate 10, and in opposition to said second spring 83 connected between plates and 10 and 11, so the systems returns automatically to the condition of Fig. 1 with subsequent back locking when releasing crank 21. The safety system of the invention is illustrated in Fig. 6 and 7. As can be noticed, between seatings 25 and 23 of the section 23′ of cam 17, respectively in locking and release position of the seat back, there is an intermediate section 24, oblique with respect to the others. As illustrated in the diagram of Fig. 7, when operating the proper release lever 21, cam 17 rotates of about 15 degrees around the axis passing through A; its end 23′ indicated as point E covers the arc b of radius r at the end of which it may start its climb to bring itself in the position of the short dash line of Fig. 6. If, on the contrary lever 21 is not operated, force F applied to seat back 11 corresponds to a torque which is discharged to gear sectors 80, 81 and to said force F applied to point A. Said force F tends to rotate cam 17 around point D so that its end E covers an arc b′ of radius r′ unsuitable with seating 12 and particularly with its section 24. The physical impossibility of releasing seat back 11 without operating on release lever 21, is thus realized.

Claims: Articulation device for reclinable seat backs comprising a first plate (10) integral to the cushion carrying a first true sector gear (80) on a horizontal crosswise axis; a second plate (11) being integral to the back, carrying a second true sector gear (81) on a second horizontal crosswise axis and parallel to that of the first sector gear (80); the second sector gear (81) being engageable in the first sector gear (80) when the respective axes coincide; a true seating (12) on the axis of the respective sector gear (80) being obtained in the first plate (10) integral to the cushion; a rotary cam (17), carrying the second plate (11) of the seat back in its movement, being fitted in said seating (12) and being driven for rotation by means of a crank (21) which can be operated by the seat occupant, who rotates the cam (17) between two extreme positions into the opening, respectively locking and releasing the back, and driving the axes of the sector gears (80, 81) to be coinciding and moving away respectively; elastic means (82, 83) acting on the cam (17) and on the crank (21) to drive the two sector gears (80, 81) into reciprocal engagement, and wherein the seating (12) and the cam (17) both have outlines consisting of at least two substantially rectilinear sections (13, 26; 13', 26') and at least one curved section (32; 32'), said outlines cooperating with one another, charactherized in that: a) the seating (12) has an outline consisting of two main opposite, substantially rectilinear sections (first and fifth sections 13 and 26) converging towards joining sections which are also rectilinear and step-like to one another (second, third and fourth sections 23, 24, 25); the other extreme of one of the main sections (first section 13) being joined to an arched section (32), whilst the other extreme of the other main section (fifth section 26) is joined to substantially rectilinear sections (sixths and seventh sections 27, 28) which are step-like to one another; the arched section (32) and the extreme one of the rectilinear sections (seventh section 28), which are joined to the main sections (13, 26), being joined to one another by means of a substantially U-shaped section (29, 30, 31); and wherein the cam (17) has an outline consisting of two main opposite sections (13', 26') so as to copy the corresponding main sections (first and fifth sections 13 and 26) of the seating (12), one in the locking position and one in the releasing position of the seat back; the main sections (13', 26') of the cam (17) converging towards a rectilinear joining section (23') corresponding to those (23, 24, 25) of the seating (12); the other extremes of said main sections (13', 26') of the cam (17) being joined through a bent section (32') , at least a rectilinear section (28') and a substantially U-shaped (30') section corresponding to those (28, 30) of the seating (12); and in that b) the rectilinear section (third section 24) of the seating (12), which is intermediate between the other joining sections (second and fourth sections 23, 25), is oblique with respect to them (23, 25). Device according to claim 1 wherein the outlines of the seating (12) and the cam (17) are such that in the locking position of the seat back the cam is being rotated so that one of its sections of main outline (26') hits against the corresponding rectilinear section (26) of the seating, its joining section (23') of the main sections (13', 26') hits against one of the joining sections (25) of the seating main sections (13, 26), whilst one of its substantially rectilinear sections (28') hits against the corresponding substantially rectilinear section (28) of the seating; and wherein the cam (17), in the releasing condition of the seat back, is rotated so that its other main section (13') and the adjacent armed section (32') correspond to the main section (13) and armed section (32) of the seating, whilst its joining section (23') to the main sections (13', 26) hits against another joining section (23) of the main sections (13, 26) of the seating (12). Device according to claim 1 wherein the step-like joining sections (23, 24,25) of the main sections (13, 26) of the seating (12) are slanting to oppose an accidental rotation of the cam (17) in the seating (12) when this is in seat back locking position and is not being rotated by operating the crank (21). Device according to claim 1 wherein the cam (17) is obtained in a disc (18) carrying a central splined hole (19), the rotation axis of which coincides with the cam's, into which hole (19) a splined appendix (20) of the crank (21) is inserted, and the plate (11) of the seat back is assembled on the external surface of said splined hole (19) of the disc (18).

Inventors: BRANDOLI LUIGI, BRANDOLI, LUIGI
Applicants: ELCAT SPA, ELCAT S.P.A.
Application year: 1990
Main classification: B60N2
IPC codes: B60N2