Rotating device of automotive seat

Abstract: A rotating device of a seat has a lower base member secured to a vehicle floor. The lower base member includes a radially inside annular raised part and a radially outside depressed annular part. An annular holder member includes a radially inside part and a radially outside part. The radially inside part is concentrically put on and secured to the radially inside annular raised part in a manner to define therebetween an annular space. An upper base member mounts thereon the seat. The upper base member includes a radially inside annular depressed part and a radially outside annular raised part. The raidally inside annular depressed part is spacedly inserted into the annular space. A first group of rolling balls are operatively arranged between the radially outside depressed annular part and the radially inside annular depressed part. A second group of rolling balls are operatively arranged between the radially inside annular depressed part and the radially outside part.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates in general to rotating seats of motor vehicles, and more particularly to rotating devices of the seats. More specifically, the present invention is concerned with seat rotating devices of a type which comprises generally a lower base member fixed to a vehicle floor, an upper base member having a seat mounted thereon and a holder member arranged between the lower and upper base members to permit rotation of the upper base member relative to the lower base member. 2. Description of the Prior Art A rotating device according to the preamble of claim 1 is known from EP 0515275. Other rotating devices are known from US 2738245 which discloses a chair with a rotating seat. EP 13649 discloses a chair with a moving seat and moving mirror. US 3659895 discloses a swivel seat locking mechanism. Another rotating device of such type is described in Japanese Utility Model First Provisional Publication 63-83058, which comprises generally a lower base member which is fixed to a vehicle floor and has an annular ridge formed thereon, an upper base member which mounts thereon a seat and has a circular opening with which the annular ridge of the lower base member is rotatably engaged, and a latch mechanism which can latch the upper base member at a desired angular position relative to the lower base member. That is, with the latch mechanism assuming inoperative condition, the upper base member (viz., the seat) can be freely rotated to a desired new angular position, and upon the latch mechanism taking operative condition, the upper base member can be latched at the desired new angular position relative to the lower base member. Fig. 7 shows another conventional rotating device for a seat, which generally comprises an annular lower base member "L" fixed to a vehicle floor (not shown), an annular upper base member "U" mounting thereon a seat (not shown) and rotatably put on the annular lower base member "L" and an annular holder member "P" fixed to the lower base member "L" to define therebetween an annular space "S" into which a radially inside part of the annular upper base member "U" is slidably and rotatably inserted. For connecting the annular holder member "P" to the annular lower base member "L", bolts "B" are used as shown. However, the above-mentioned rotating devices have failed to give users satisfaction due to complicated and expensive construction thereof. Particularly, in the device of Fig. 7, it has been very difficult to obtain a smoothed rotation of the upper base member "U" relative to the lower base member "L". SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a rotating device of an automotive seat, which is free of the above-mentioned drawbacks. It is an object of the present invention to provide a rotating device of an automotive seat which is simple in construction, not expensive and assures a smoothed rotation of the seat. According to the present invention, there is provided a rotating device of a seat, according to claim 1. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings, in which: Fig. 1 is a sectional view of a left half part of a rotating device according to the present invention; Fig. 2 is a sectional view of a left half part of an annular upper base member employed in the rotating device of the present invention; Fig. 3 is a sectional view of a left half part of an annular holder member employed in the rotating device of the present invention; Fig. 4 is an exploded view of the rotating device of the present invention; Fig. 5A is a plan view of a first annular plate member employed in the rotating device of the present invention; Fig. 5B is a side view of the first annular plate member; Fig. 5C is an enlarged sectional view of a part of the first annular plate member; Fig. 6A is a plan view of a second annular plate member employed in the rotating device of the present invention; Fig. 6B is a side view of the second annular plate member; Fig. 6C is an enlarged plan view of a part of the second annular plate member; and Fig. 7 is a sectional view of a conventional rotating device of a seat. DETAILED DESCRIPTION OF THE INVENTION Referring to Figs. 1 to 5C, particularly Fig. 4, there is shown a rotating device 10 of an automotive seat, which is an embodiment of the present invention. Designated by numeral 1 in Fig. 4 is the seat which is to be mounted on the rotating device 10 of the invention. The seat 1 comprises a seat cushion part 2 and a seat back part 3. Usually, a reclining device is provided for adjusting an inclination angle of the seat back part 3 relative to the seat cushion part 2. As is seen from Figs. 4 and 1, the seat rotating device 10 comprises five major parts, which are a lower base member 11 with a circular opening 12, a first annular plate member 31, an upper base member 13 with a circular opening 14, a second annular plate member 34 and an annular holder member 15 which are concentrically arranged about a common axis "O" (see Fig. 7). As will become apparent as the description proceeds, the upper base member 13 mounts thereon the seat 1 and is rotatable relative to the lower base member 11, and the annular holder member 15 functions to slidably hold a radially inside part of the upper base member 13 on the lower base member 11. The lower base member 11 is securely disposed on a vehicle floor (not shown) by means of bolts or the like, and the upper base member 13 has the seat 1 tightly mounted thereon. As is best seen from Fig. 1, the lower base member 11 has a radially inside part 11a which is raised at a stepped portion 11b. A radially inside part 13a of the upper base member 13 surrounds the stepped portion 11b with a certain annular clearance defined therebetween. The annular holder member 15 has a depressed radially inside part 15a which is put on and secured to the raised radially inside part 11a of the lower base member 11 by means of bolts 18 and nuts. With this, an annular space is defined between the lower base member 11 and the annular holder member 15, into which the radially inside part 13a of the upper base member 13 is spacedly inserted. The radially inside part 13a of the upper base member 13 is depressed at a stepped portion 13b. Referring to Fig. 4, the upper base member 13 is equipped with a bracket 21 by which a spring-biased latch member 22 is operatively held. The latch member 22 is selectively engageable with one of notches 15d formed in the annular holder member 15. That is, upon engagement of the latch member 22 with a selected one notch 15d, the rotatable upper base member 13 is latched at a desired angular position relative to the fixed lower base member 11 to which the annular holder member 15 is secured. Referring back to Fig. 1, the annular holder member 15 has a radially outside end part 15b which is raised at a bent up portion 15c. As shown, the outside end part 15b faces the stepped portion 13b of the upper base member 13. As is seen from Fig. 2, the upper base member 13 has a first annular guide groove 13d at a junction portion between the radially inside part 13a and the stepped portion 13b. The first annular guide groove 13d faces upward and extends concentrically around the common axis "O". Within the guide groove 13d, there are put a plurality of rolling balls 27 whose upper ends abut against the bent up portion 15c of the annular holder member 15, as shown. As will be understood from Figs. 1 and 4, the rolling balls 27 are respectively and rotatably held in openings 35 formed in the second annular plate member 34 which is freely put between the radially inside part 13a of the upper base member 13 and the bent up portion 15c of the annular holder member 15. As is seen from Figs. 1 and 2, the upper base member 13 has further a second annular guide groove 13c at a middle portion of the radially inside part 13a. The second annular guide groove 13c faces downward and extends concentrically around the common axis "O". As is seen from Fig. 1, the tower base member 11 has a third annular guide groove 11c which exactly faces the above-mentioned second annular guide groove 13c of the upper base member 13 to define therebetween an annular guide track. Within this guide track, there are put a plurality of rolling balls 25. As will be understood from Figs. 1 and 4, the rolling balls 25 are respectively and rotatably held in openings 32 formed in the first annular plate member 31 which is freely put between the lower base member 11 and the radially inside part 13a of the upper base member 13. With usage of the rolling balls 25 and 27, the upper base member 13 can rotate smoothly about the common axis "O" relative to the fixed lower base member 11. Due to usage of the first and second annular plate members 31 and 34, the rolling balls 25 and 27 are kept spaced from each other by a given distance even under rotation of the upper base member 13 about the common axis "O" relative to the lower base member 11. Referring to Figs. 5A, 5B and 5C, there is shown the detail of the above-mentioned first annular plate member 31. As is seen from Fig. 5A, the openings 32 of the first annular plate member 31 are six in number and arranged at evenly spaced intervals. That is, six rolling balls 25 are used for the guide track defined by the second and third annular guide grooves 13c and 11c. Of course, more than six rolling balls 25 may be used. Each opening 32 is elliptic in shape. That is, each opening 32 is elongated in a radial direction of the plate member 31. As is seen from Figs. 5B and 5C, each opening 32 is rimmed by a thicker peripheral portion 33 thereof, so that the rolling ball 25 is stably held In the opening 32 under rotation of the upper base member 14 relative to the fixed lower base member 11. Referring to Figs. 6A, 6B and 6C, there is shown the detail of the above-mentioned second annular plate member 34. As is seen from Fig. 6A, the openings 35 of the second annular plate member 34 are six in number and arranged at evenly spaced Intervals. That is, six rolling balls 27 are used for the first annular guide groove 13d of the upper base member 13. Of course, more than six rolling balls 27 may be used. As is seen from Figs. 6B and 6C, each opening 35 is elliptic in shape. That is, each opening 35 is elongated in a radial direction of the plate member 34. Each opening 35 has a slit 39 which extends radially outward therefrom. Furthermore, each opening 35 is sandwiched by two thicker portions 33 of the plate member 34, so that the rolling ball 27 is stably held in the opening 35 under rotation of the upper base member 14 relative to the fixed lower base member 11. When, with the latch member 22 kept disengaged from the notch 15d of the annular holder member 15, the seat 1 mounted on the rotating device 10 is applied with a certain force, the seat 1 is rotated about the axis "O" together with the upper base member 13. This rotating movement is smoothly carried out due to usage of the rolling balls 25 and 27. When, upon the seat 1 being brought to a desired new angular position, an operation lever 22A of the latch member 22 is released from an operator's hand, the latch member 22 is brought into engagement with a new notch 15d of the annular holder member 15. With this, the seat 1 is latched at the desired new angular position. In the following, advantages of the present invention will be described. First, because the radially inside part 13a of the upper base member 13 is supported by both the lower base member 11 and the annular holder member 15 through respective rolling balls 25 and 27, the upper base member 13 can be stably supported without suffering a play. That is, smooth turning of the seat 1 is achieved. Second, because the rolling balls 25 and 27 on the respective guide tracks are evenly spaced by the first and second annular plate members 31 and 34, the weight of the seat 1 Is evenly applied to the lower base member 11. This promotes the smoothed turning of the seat 1. Third, because of its simple construction, the seat rotating device 10 of the invention can be produced at a low cost.

Claims: A rotating device (10) of a seat, comprising: a lower base member (11) adapted to be secured to a fixed member, said lower base member including a radially inside annular raised part (11a) and a radially outside depressed annular part (11c); an annular holder member (15) including a radially inside part (15a) and a radially outside part (15b), said radially inside part being concentrically put on and secured to said radially inside annular raised part in a manner to define therebetween between said radially outside depressed annular part (11c) of said lower base member (11) and said radially outside part (15b) of said annular holder member (15) an annular space; an upper base member (13) adapted to mount thereon the seat, said upper base member including a radially inside annular depressed part (13a) and a radially outside annular raised part (13), said radially inside annular depressed part (13a) being spacedly inserted into said annular space; a first group of rolling balls (25) operatively arranged between said radially outside depressed annular part (11c) of said lower base member (11) and said radially inside annular depressed part (13a) of said upper base member (13); and a second group of rolling balls (27) operatively arranged between said radially inside annular depressed part (13a) of said upper base member (13) and said radially outside part (15b,15c) of said annular holder member (15), which is characterised in that said radially inside annular depressed part (13a) and said radially outside annular raised part (13) are connected through a stepped portion (13b), in that said second group of rolling balls (27) are received in an annular guide track while contacting a junction portion between said radially inside annular depressed part (13a) and the stepped portion (13b), in that said radially outside part (15b) of said annular holder member (15) and said radially inside part (15a) of the same are connected through a bent up portion (15c) of the annular holder member (15), in that said bent up portion (15c) is arranged to contact each of said second group of rolling balls (27) from an oblique direction with respect to both said radially inside annular depressed part (13a) and the stepped portion (13b) so that each ball (27) is supported in a three-point supported manner, and in that , a first annular plate member (31) is freely and concentrically put between said radially outside depressed annular part and said radially inside annular depressed part, said first annular plate member (31) having equally spaced openings (32) into which the rolling balls (25) of said first group are respectively and rotatably received; and a second annular plate member (34) is freely and concentrically put between said radially inside annular depressed part and said radially outside part, said second annular plate member having equally spaced openings (35) into which the rolling balls (27) of said second group are respectively and rotatably received. A rotating device as claimed in claim 1, in which the rolling balls of said first group (25) are received in an annular guide track defined by said radially outside depressed annular part and said radially inside annular depressed part. A rotating device as claimed in claim 2, in which the rolling balls (27) of said second group are received in a second annular guide track defined by said radially inside annular depressed part and said radially outside part. A rotating device as claimed in claim 2, in which said first annular guide track comprises: an annular groove (11c) formed on an upper surface of said radially outside depressed annular part; and an annular groove (13c) formed on a lower surface of said radially inside annular depressed part. A rotating device as claimed in claim 3, in which said second annular guide track comprises: an annular groove formed on an upper surface of said radially inside annular depressed part; and a bent up portion (15c) of said radially outside part. A rotating device as claimed in claim 1, in which each of the openings (32,35) of said first and second annular plate members is elliptic in shape. A rotating device as claimed in claim 6, in which each of said openings (32,35) is elongated in a radial direction of the corresponding annular plate member. A rotating device as claimed in claim 1, in which each of the openings of said first annular plate member is rimmed by a thicker peripheral portion (33) in the first annular plate member. A rotating device as claimed in claim 1, in which each of the openings of said second annular plate member is sandwiched by two thicker portions (38) of the second annular plate member. A rotating device as claimed in claim 9, in which each of the openings of said second annular plate member has a slit (39) which extends radially outward from the opening. A rotating device as claimed in claim 1, further comprising a latch mechanism by which said upper base member is latched at a desired angular position relative to said lower base member. A rotating device as claimed in claim 11, in which said latch mechanism comprises: a spring biased latch member (22) held by said upper base member; and notches (15d) formed in said annular holder member (15), wherein when said upper base member is tumed to a certain angular position, said latch member is permitted to engage with one of said notches.

Inventors: EZUKA YOSHIAKI, KONDO TORU, YAMAUCHI YOSHIHIKO, YONEKURA MASAMI, EZUKA, YOSHIAKI, KONDO, TORU, YAMAUCHI, YOSHIHIKO, YONEKURA, MASAMI
Applicants: IKEDA BUSSAN CO, IKEDA BUSSAN CO., LTD.
Application year: 1997
Main classification: B60N2
IPC codes: B60N2