Vehicle seat with a retractable sub seat

Abstract: A vehicle seat comprises a main seat portion (2), a main backrest (4) rotatably attached to the main seat portion (2), and a retractable sub vehicle seat (15). The sub vehicle seat has a recess (16) formed on a rear side of the main backrest (4), a sub backrest (25) rotatably attached to the main backrest (4), and a locking mechanism (31-39) for holding the sub backrest (25) in a retracted position or an upright position. The main backrest (4) has a frame assembly (6,7) rotatably attached to the main seat portion (2), a front cushion (8) attached to a front side of the frame assembly (6,7), and a rear cushion (18) attached to a rear side of the frame assembly (6,7). The rear cushion (18) is positioned in a bottom of the recess (16) for supporting buttocks of a passenger who sits on the recess (16). The rear cushion (18) has a deeper portion (19) for supporting the buttocks and a raised portion (17) for supporting thighs of the passenger. The locking mechanism (31-39) comprises a locking plate (31) having a first groove (33) and a second groove (34) fixed to the sub backrest (25), and a locking spring (35) attached to the main backrest (4) and selectively engageable with the first groove (33) and the second groove (34).

Description: The present invention relates to a vehicle seat, and more particularly to a vehicle seat having a retractable sub vehicle seat disposed on a backrest of the vehicle seat, according to the features of the preamble of independent claim 1. There is publicly known a vehicle seat having a retractable sub vehicle seat at a rear side of a backrest thereof. For example, Japanese Utility Model Publication No. 62-24581 describes a vehicle seat of the above type which comprises a main seat portion attached to a vehicle body, a main backrest rotatably attached to the main seat portion, and a retractable sub vehicle seat which has a recess for receiving buttocks of a passenger formed on a rear side of the main backrest and a sub backrest rotatably attached to the main backrest. The sub backrest is rotatable between a retracted position in which it is substantially parallel to the main backrest and an upright position in which it is substantially perpendicular to the main backrest. The sub backrest is adapted to be accommodated within the recess when retracted. The sub vehicle seat further has a locking mechanism for holding the sub backrest in the retracted position or the upright position. The above-mentioned vehicle seat has some disadvantages. The first disadvantage is that since there is no cushion of a suitable thickness in the recess for supporting the buttocks of the passenger, the sub vehicle seat is uncomfortable to sit on. The second disadvantage is that since the sub backrest is held in the upright position only by the locking mechanism, the locking mechanism has to be strongly built and is of large size, so that the sub backrest is of increased thickness. With the increase in thickness of the sub backrest, the cushion of the main seat portion becomes thinner, which renders it uncomfortable. The third disadvantage is that when using the sub vehicle seat the conventional main seat portion comes into contact with a dashboard of the vehicle when the vehicle seat is desired to be slid forward to increase the distance from the rear seat, thereby preventing the vehicle seat from sliding forward. It is, therefore, an object of the present invention to provide a vehicle seat having a retractable sub vehicle seat, which is capable of reducing the above mentioned problems. The invention is illustrated by way of example in the acompanying drawings, in which: Fig. 1 is a side view of a vehicle seat according tothe present invention; Fig. 2 is a perspective view of the vehicle seat; Fig. 3 is a perspective view of a main backrest; Fig. 4 is a sectional view of a main backrest and a retractable sub vehicle seat; Fig. 5 is an exploded perspective view of a frame assembly of the main backrest and a frame of a sub backrest; Fig. 6 is a sectional view of the main backrest in a horizontal state and the sub backrest in an upright position; Fig. 7 is an enlarged sectional view of a part of Fig. 6; Fig. 8 is a side view of a locking mechanism in which the sub backrest is positioned in a retracted position; Fig. 9 is a side view of the locking mechanism in which the sub backrest is positioned in the upright position: Fig. 10 is an exploded view of a height control means; Fig. 11 is an explanatory view showing operation of the height control means; Fig. 12 is a side view of a reclining device; and Fig. 13 is an explanatory view showing a relationship between a driver and a passenger who sits on the retractable sub vehicle seat. Referring to the drawings, as shown in Fig. 1, a vehicle seat 1 according to one embodiment of the present invention has a main seat portion 2 slidably attached to a vehicle body 80, a main backrest 4 rotatably attached to the seat portion 2 by a shaft 3, a headrest 12 attached to an upper portion of the backrest 4, and a reclining device 5 for adjusting the angle of inclination of the backrest 4 with respect to the main seat portion 2. The backrest 4 has a central supporting portion 10 for supporting a back of a passenger who sits on the main seat portion 2 and side supporting portions 11 disposed on both sides of the central portion 10. Inside the central supporting portion 10 are disposed a frame assembly F comprised of a tubular frame 6 preferably in the shape of a rectangular frame and a vertical supporting plate 7 fixed inside the frame 6 as shown in Figs. 4 and 5. The frame assembly F is surrounded by a front cushion 8 and a rear cushion 18 which are made of urethane foam or the like, and are enclosed by respective outer skins 9. The main backrest 4 has a retractable sub vehicle seat 15 at a rear side thereof. The sub vehicle seat 15 has a recess 16 disposed on a rear side of the main supporting portion 10, a sub backrest 25 rotatable between a retracted position in which the sub backrest 25 is substantially parallel with the main backrest 4 and is accommodated within the recess 16 and an upright position in which the sub backrest 25 is approximately perpendicular to the main backrest 4, and a seat belt 66. The recess 16 is of a size such that a child can sit thereon facing rearwards when the main backrest 4 is rotated forwards to a position parallel with the main seat portion 2, as shown in Figs. 1 and 2. The side supporting portions 11 are located on both sides of the recess 16, and can then be used as arm rests of the sub vehicle seat 15. The bottom of the recess 16 constitutes a sub seat portion 17 of the sub vehicle seat 15. A deeper portion 19 for supporting the buttocks of the passenger and a raised portion 72 for supporting femoral regions of the passenger are formed on the sub seat portion 17. However, when the thickness of the rear cushion 18 of the sub seat portion 17 is insufficient to form a suitable raised portion 72, a separate cushion pad 20 can be used. In the present embodiment as shown in Fig. 6, the cushion pad 20 for supporting the femoral regions of the passenger is sewed to the sub seat portion 17 by thread. The cushion pad 20 has a profile such as to be thin at a base portion thereof and thicker toward a leading end thereof, like an aerofoil. The cushion pad 20 can be stowed in the deeper portion 19 by rotating it about the sewed portion thereof as a pivot when retracting the sub backrest 25 into the recess 16. The cushion pad 20 may also be detachably attached thereto by a touch and close tape or the like. The sub backrest 25 is formed by a plate-like frame 26, a cushion 27 such as urethane foam surrounding the frame 26, and an outer skin 28 enclosing the cushion 27. A pair of flanges 29 are disposed on both sides of the frame 26, and the flanges 29 and brackets 67 fixed to the frame assembly F are rotatably connected to each other by bolts 30 and nuts 69. As shown in Fig. 5, a locking spring 35 is disposed on a rear face of the vertical supporting plate 7. The locking spring 35 has a pair of attaching portions 36 attached to the vertical supporting plate 7 by fasteners 70 (Fig. 8), a pair of contacting portions 37 resiliently coming into contact with the vertical supporting plate 7, and a pair of engaging portions 38 engaging with a pair of locking plates 31 fixed to the frame 26. One of the outer ends 39 of the engaging portions 38 protrudes toward the outside of the main backrest 4 through the bracket 67, and an operating knob 68 is attached to the exposed outer end 39. Each locking plate 31 has a first groove 33 engaging with the engaging portion 38 of the locking spring 35 when the sub backrest 25 is displaced to the retracted position as shown in Fig. 8, and a second groove 34 engaging with the engaging portion 38 when the sub backrest 25 is displaced to the upright position as shown in Fig. 9. The engaging portions 38 can be released from the locking plates 31 by turning the operating knob 68, so that the sub backrest 25 can turn freely. As shown in Fig. 4, an upper portion 43 of the main backrest 4 to which the headrest 12 is attached has a supporting wall 44 that comes into contact with a rear or outer surface of the sub backrest 25 when the sub backrest 25 is displaced to the upright position. In the present arrangement, since the supporting wall 44 receives the load applied to the sub backrest 25, the load applied to the locking plates 31 and the locking spring 35 which hold the sub backrest 25 in the upright position is reduced. Therefore, the locking plates 31 and the locking spring 35 can be miniaturized to a relatively simple construction, without the need for a massive tooth and ratchet mechanism. Further, since the locking plates 31 and the locking spring 35 are miniaturized, which reduces the thickness of the sub backrest 25, two of the cushions 8, 18 of the main seat portion 2 can be thicker, which increases the comfort of the seat. The angle of the supporting wall 44 is suitably designed according to the intended purpose of the retractable sub vehicle seat 15. As shown in Fig. 10, a pair of upper brackets 55 are fixed to both sides of the frame assembly F of the main seat portion 2. A shaft 57 is fixed to a lower-rear portion of each upper bracket 55, and rear portions of lower brackets 56 are rotatably attached to the shafts 57, respectively. The lower brackets 56 are fixed to the upper rails 62 which are slidably engaged with the lower rails 63 fixed to the vehicle body 80. When the sub vehicle seat 15 is used, the vehicle seat 1 is desirably slid forward so as to increase the distance from a rear seat (not illustrated). When the vehicle seat 1 cannot be sufficiently slid forward due to the contact with a dashboard 65 of the vehicle 80 as shown by a imaginary line in Fig. 11, the headrest 12 and the main seat portion 2 are lowered. A height control means 58 for reducing the height of the seat portion 2 is, as shown in Fig. 10, fixed to the lower bracket 56 by screws 71. The height control means 58 has a locking pin 59 which selectively engages with an upper hole 60a and a lower hole 60b, both of which are formed in the upper bracket 55, due to the resiliency of a spring (not illustrated). When the locking pin 59 engages with the lower hole 60b, the main seat portion 2 is, as shown in the imaginary line in Fig. 11, held at a normal position which is appropriate for an adult to sit on the main seat portion 2. When the locking pin 59 engages with the upper hole 60a, the front of the main seat portion 2 is pivoted downward about the shaft 57 toward the floor of the vehicle 80 and the main seat portion 2 is lowered to a position in which the main seat portion 2 does not contact the dashboard 65. The reclining device 5 disposed between the main seat portion 2 and the main backrest 4 has a sector-shaped gear 47 fixed to the frame assembly F, a ratchet lever 48, rotatably attached on the upper bracket 55 by a shaft 73, for meshing with the gear 47, and a release lever 51 for releasing the ratchet lever 48 from the gear 47. The gear 47 has a first toothed portion 49 for adjusting the angle of use of the main backrest 4, a second toothed portion 50 for holding the main backrest 4 in the retracted position in which the main backrest 4 is substantially parallel with the main seat portion 2, and a non-toothed portion 74 disposed between the first toothed portion 49 and the second toothed portion 50. The operation of this embodiment will be described hereinbelow. When the retractable sub vehicle seat 15 is to be used, the release lever 51 of the reclining device 5 is turned, the ratchet lever 48 is released from the first toothed portion 49 of the gear 47, and the main backrest 4 is turned so as to be parallel with the main seat portion 2. When the release lever 51 is released, the ratchet lever 48 engages with the second toothed portion 50, and the main backrest 4 is held in the horizontal state. The locking pin 59 of the height control means 58 is removed from the lower hole 60b of the upper bracket 55, and inserted into the upper hole 60a. Then, after the main seat portion 2 has thus been moved from the normal position to the low position, the lower rail 63 and the upper rail 62 are unlocked, and the vehicle seat 1 is slid forward. The main seat portion 2 positioned at the low position can be slid forward without coming into contact with the dashboard 65. Next, the operating knob 68 of the sub vehicle seat 15 is pushed, and the engaging portions 38 of the locking spring 35 are released from the first grooves 33 of the locking plates 31, so that the sub backrest 25 of the sub vehicle seat 15 can be rotated about the shaft 30 as a center until the rear or outer·surface of the sub backrest 25 comes into contact with the supporting wall 44 of the backrest 4. When the rear surface comes into contact with the supporting wall 44, the engaging portions 38 of the locking spring 35 are engaged with the second grooves 34 of the locking plates 31, so that the sub backrest 25 is held at the upright position. When the cushion pad 20 in the recess 16 is transferred from the deeper portion 19 to the raised portion 72, the sub vehicle seat 15 becomes usable. In the sub vehicle seat 15 of the present invention, the bottom of the recess 16 is used as the sub seat portion 17. However, in the sub seat portion 17 are disposed the deeper portion 19 for supporting the buttocks of the passenger and the raised portion 72 for supporting the femoral region of the passenger, which increases the comfort of sitting thereon. Since another cushion pad 20 can be attached to the recess 16, the comfortable feeling of sitting thereon can be maintained even when the thickness of the rear cushion 18 of the sub seat portion 17 is insufficient to form the raised portion 72. Further, since the cushion pad 20 is formed so as to have such a size as to enter into a portion between the sub backrest 25 and the deeper portion 19, the handling thereof is convenient when the sub backrest 25 is retracted in the recess 16. Besides, when the child sits on the sub vehicle seat 15, the driver can easily watch the child, as shown in Fig. 13.

Claims: A vehicle seat with a retractable sub vehicle seat (15), comprising: a main seat portion (2) attached to a vehicle body; a main backrest (4) rotatably attached to the main seat portion (2), a recess (16) formed in a rear side of the main brackrest (4) to form a sub seat portion (17) for receiving buttocks of a passenger and a sub backrest (25) rotatably attached to the main backrest, said sub backrest (25) being displaceable between a retracted position in which the sub backrest (25) is substantially parallel with the main backrest (4) and is accommodated within the recess (16) and an upright position in which the sub backrest (25) is approximately perpendicular to the main backrest (4); and a locking mechanism (31-39) for holding the sub backrest (25) in the retracted position or the upright position; characterised in that said main backrest (4) has a frame assembly (6, 7) rotatably attached to the main seat portion (2), a front cushion (8) attached to a front side of the frame assembly (6, 7) for supporting a back of a passenger who sits on the main seat portion (2), and a rear cushion (18) attached to a rear side of the frame assembly (6, 7), said rear cushion (18) being positioned in a base of the recess (16) for supporting the buttocks of the passenger who sits on the recess (16), and in that a supporting wall (44) is formed on a peripheral wall of the recess (16) for supporting a rear side of the sub backrest (25) when the sub backrest (25) is displaced into the upright position. A vehicle seat according to Claim 1, wherein a deeper portion (19) for supporting the buttocks of the passenger and a raised portion (17) for supporting thighs of the passenger are formed in the rear cushion (18). A vehicle seat according to claim 2, wherein a cushion pad (20) is attached to a rear surface of the rear cushion (18), the arrangement being such that said cushion pad (20) can be accommodated in the deeper portion (19) when the sub backrest (25) is positioned in the retracted position. A vehicle seat according to any preceding claim, wherein said main backrest (4) comprises a main supporting portion (10) for supporting a back of the passenger who sits on the main seat portion (2) and side supporting portion (11), located on both sides of the main supporting portion (10), wherein said recess (16) is formed in a rear side of the main supporting portion (10) below an upper portion (43) of the main supporting portion, and wherein said supporting wall (44) is formed on a lower surface of the upper portion (43). A vehicle seat according to any preceding claim, wherein said locking mechanism comprises a locking plate (31) fixed to the sub backrest and, having a first groove (33) and a second groove (34) and a locking spring (35) attached to the main backrest (4) and selectively engageable with the first groove (33) and the second groove (34). A vehicle seat according to claim 5, wherein said locking spring (35) comprises an attaching portion (36) attached to the frame assembly by a fastener (70), a contacting portion (37) resiliently engaging the frame assembly (6,7), and an engaging portion (38) resiliently engaging with the locking plate (31) due to the contact of the frame assembly (6,7) and the contacting portion (37). A vehicle seat according to claim 5 or 6, wherein an outer end (39) of said locking spring protrudes toward the outside of the main backrest, and wherein an operating knob (68) is attached to an exposed portion of the outer end (39). A vehicle seat according to any one of claims 1-7, wherein said main seat portion (2) is slidably attached to the vehicle body, and wherein a height control means (58-60) for reducing the height of the main seat portion (2) is disposed between the main seat portion (2) and the vehicle body (80). A vehicle seat according to claim 8, further comprising an upper bracket (55) mounted to the main seat portion (2) and a lower bracket (56) slidably mounted to the vehicle body (80), wherein a rear end portion of said upper bracket (55) and a rear end portion of said lower bracket (56) are pivotably connected with each other and wherein said height control means is disposed between a front end portion of the upper bracket (55) and a front end portion of the lower bracket (56). A vehicle seat according to claim 9 wherein said upper bracket comprises an upper hole (60 a ) and a lower hole (60 b ) arranged one above the other, and wherein said height control means comprises a locking pin (59) selectively engageable with the upper hole (60 a ) and the lower hole (60 b ).

Inventors: SHOUJI TOMOMI, TAKEI YASUCHIKA, YOSHIDA MASAMI, SHOUJI, TOMOMI, TAKEI, YASUCHIKA, YOSHIDA, MASAMI, Takei, Yasuchika, Houshakuji Haitsu L-103
Applicants: TS TECH CO LTD, TS TECH CO., LTD
Application year: 1996
Main classification: B60N2
IPC codes: B60N2, B60R22