Seat adjustment mechanisms

Abstract: A seat adjustment mechanism principally for vehicle seats comprises a frame (11) connected to a base (10) by front and rear linkages (12a, 12b, 12c, 12d). A mechanism (24, 25, 35) is provided that is operated by a handle (41) with a first movement of the handle (41) unlocking the front linkages (12a, 12b) to allow the tilt of the frame (11) to be adjusted relative to the base (10) and continued movement of the handle (41) unlocking both linkages (12a, 12b, 12c, 12d) to allow the height of the frame (11) to be adjusted relative to the base (10). This is achieved by successively pivoting lever arms (24, 25) that successively unlock the linkages (12a, 12b, 12c, 12d).

Description: The invention relates to seat adjustment mechanisms. Many seats, particularly vehicle seats, are mounted on a frame connected to a base by linkages to allow the position of the seat to be adjusted relative to the base. For example, a mechanism may be provided that allows the height of the seat to be adjusted and/or a mechanism can be provided to allow the seat to be tilted. Moreover, there is known from DE-A-2 409 579 a seat adjustment mechanism having a fixed position, a tiltable position and a height adjustment position. According to the invention, there is provided a seat adjustment mechanism comprising a seat support frame carried on a base for movement relative thereto by a linkage, the linkage comprising first and second linkages, the first linkage being arranged towards a first end of the frame and the second linkage being arranged towards a second end of the frame, a control mechanism being provided which, in one position, fixes the position of the frame relative to the base and which, in a further position, allows movement of both ends of the frame relative to the base, characterized in that each linkage includes a block slidable in an associated slot in the frame during said movement of the frame, the control mechanism, when in said one position, locks the blocks to the frame, the control mechanism having a second position in which the control mechanism releases one of the blocks to allow movement of the associated end of the frame relative to the base, the control mechanism, in said further position, releasing both blocks to allow said movement of said both ends of the frame relative to the base. The following is a more detailed description of an embodiment of the invention, by way of example, reference being made to the accompanying drawings in which:- Figure 1 is a perspective view of a seat adjustment mechanism, Figure 2 is a side elevation of a part of the seat adjustment mechanism of Figure 1 showing a cam plate latching to a first lever arm of the mechanism, Figure 3 is a side elevation of the first lever arm of the mechanism of Figures 1 and 2, and Figure 4 is a side elevation of a second lever arm of the mechanism of Figures 1 and 2. Referring first to Figure 1, the seat adjustment mechanism comprises a base indicated generally at 10, a frame indicated generally at 11 and two pairs of Y-shaped linkages indicated generally at 12a,12b,12c,12d connecting the frame 11 to the base 10. The base 10 is generally rectangular in plan view and formed by four interconnected members 13. Since the seat adjustment mechanism is designed to be installed in a vehicle, the base 10 is for attachment to the floor of a vehicle. The frame 11, which, in use, carries a vehicle seat (not shown), is formed by two parallel but spaced L-shaped side channels 14a,14b. Each channel has a vertical flange 15a,15b and a horizontal outwardly projecting flange 16a,16b. Each vertical flange 15a,15b is provided with a pair of aligned but spaced horizontal slots 18a,18b and 18c,18d for a purpose to be described below. The Y-shaped linkages 12a,12b and 12c,12d of each pair are arranged in parallel planes so that one pair of linkages 12a,12b connect respective first ends of the channels 14a,14b to the base 10 (called the "front" end) and the other pair of linkages 12c,12d connect respective other ends of the channels to the base 10 (called the "rear" end). Each Y-shaped linkage comprises a main link 17a,17b,17c,17d pivotally connected to a respective corner of the frame 10 at a lower end and carrying a pin 19a,19b,19c,19d at its opposite, upper, end which projects into an associated one of the slots 18a,18b,18c,18d and carries a slider block 20a,20b,20c,20d guided for sliding movement along the associated slot 18a,18b,18c,18d. Each Y-shaped linkage 12a,12b,12c,12d also includes a second link 21a,21b,21c,21d pivotally connected at one end intermediate the ends of the associated main link 17a,17b,17c,17d and pivotally connected at the other end to an associated channel 14a,14b adjacent an end of the channel 14a,14b. A rod 22a,22b extends between the main links 17a,17b and 17c,17d of each pair of links in a direction normal to the planes of the links of each pair. The rod 22a,22b thus constrains the associated linkages 12a,12b,12c,12d of each pair to move together. Each pair of Y-shaped linkages 12a,12b,12c,12d is provided with a coil spring 23 having one end connected to the associated rod 22a,22b and the other end connected to a rod (not shown) carried by one of the second links 21a,21d at the pivotal connection between the second link 21a,21d and the associated main link 17a,17d. The coil spring 23 provides a torque that tends to close the angle between the second links 21a,21b,21c,21d and the associated main links 17a,17b,17c,17d so tending to hold the channels 14a,14b at a maximum spacing from the base 10. This movement is limited only by engagement of the slider blocks 20a,20b,20c,20d with an end of the associated slots 18a,18b,18c,18d. Referring now additionally to Figures 2, 3, and 4, one of the channels 14b carries a control mechanism that allows both the tilt and the height of both channels 14a,14b to be adjusted relative to the base 10. The control mechanism includes first and second lever arms 24,25. As best seen in Figure 3, the first lever arm 24 is an elongate platelike member which, at one end, is pivotally connected to the vertical flange 15b of the associated channel 14b adjacent the front end of the channel 14b. The arm 24 is then cranked in its own plane and after the crank an upper edge of the lever arm 24 is provided with a plurality of teeth 26. In the position of the lever arm 24 shown in Figure 1, these teeth 26 engage corresponding teeth on the slider block 20b in the adjacent slot 18b. The end of the first lever arm 24 remote from the pivot carries a latch member 27 in the form of a generally rectangular plate carrying two horizontally projecting pins 28,29 and formed at its free end with a U-shaped recess 30 bounded by a pair of upper and lower spaced limbs 31a,31b. The second lever arm 25 is generally a mirror image of the first lever arm being provided with a similarly arranged pivot crank and teeth 32 which engage with cooperating teeth on the slider block 20c in the associated slot 18c in the position of the second lever arm 25 shown in Figure 1. However, the second lever arm 25 carries a latch member 33 which, while rectangular, is provided at its free end with a single projection 34. The first end second lever arms 24,25 are interconnected by a coil spring 44 which tends to pivot the arms 24,25 in an upward direction. As best seen in Figure 2, in the position of the first and second lever arms 24,25 shown in Figure 1, the projection 34 of the second arm 25 extends into the U-shaped recess 30 at the end of the first operating arm 24 with the projection 34 engaging the lowermost limb 31b. The vertical flange 15b of this channel 14b also carries an operating or control member in the form of a cam plate 35 which is generally triangular in shape and mounted for pivotal movement about a horizontal axis 36. One corner of the cam plate 35 defines a hook-shaped catch 37 which, in the position of the first and second lever arms 24,25 shown in Figure 2, receives the pin 29 on the latch member 27 of the first lever arm 24. An upwardly inclined cam surface 38 extends away from the catch 37 to a next adjacent corner of the cam plate 35. The cam plate 35 also has an upper corner provided with a hole 39 which receives one end of an operating rod 40 whose other end is connected to an operating handle 41 best seen in Figure 1 and carried for pivotal movement on a mounting 42 depending from the channel 14b. The arrangement is such that upward pivotal movement of the handle 41 causes anti-clockwise rotation of the cam plate 35, as viewed in Figure 2. The seat adjustment mechanism operates as follows. In the position of the first and second lever arms 24,25 shown in Figures 1 and 2, the channels 14a,14b are locked relative to the base 10. This is achieved by the pin 29 engaging in the catch 37 so holding the first lever arm 24 in a position in which the associated teeth 26 engage the associated slider block 20b. Since the projection 34 on the second lever arm 25 engages the lower limb 31b of the recess 30 on the first lever arm 24, the second lever arm 24 is also prevented from pivoting thus holding the second lever arm 25 in a position in which its teeth 32 engage the teeth on the associated slider block 20c. Since the slider blocks 20b,20c cannot slide, the angle between the main links 17a,17b,17c and 17d and the second links 21a,21b,21c,21d is fixed so preventing relative movement between the channels 14a,14b and the base 10. Thus the height and tilt of the channels 14a,14b are fixed relative to the base 10. If the handle 41 is pivoted upwardly, the cam plate 35 begins to rotate about the horizontal axis 36. As the pin 29 clears the catch 37, the first lever arm 24 is released for movement. At the same time, the second pin 28 contacts the cam surface 38 and continued rotation of the cam plate 35 causes the cam surface 38 to press downwardly on the pin 28 so pivoting the first lever arm 24 downwardly. This disengages the teeth 26 from the associated slider block 20b. During this movement of the first lever arm 24, there is no movement of the second lever arm 25 because of the lost motion provided by the recess 30. Although the projection 34 disengages from the lower limb 31b, it moves in the space between the limbs 31a,31b. The engagement of the projection 34 with the upper limb 31 can be felt during operation of the handle 41. If rotation of the handle 41 is halted in this position, the tilt of the channels 14a,14b (and thus the tilt of the front of an associated seat) relative to the base 10 can be adjusted by either applying downward pressure on the frame 11 or by releasing the downward pressure to allow the front Y-shaped links to close under the action of the associated coil spring 23. When a required tilt is achieved, the handle 41 can be pivoted in a reverse direction so disengaging the cam surface 38 from the pin 28 and allowing the first lever arm 24 to perform a reverse pivotal movement under the action of the spring 44. This reverse pivotal movement brings the teeth 26 on the first lever arm 24 into engagement with the teeth on the associated slider block 20b so preventing further movement of the slider block 20b and holding the frame 11 at the desired tilt relative to the base 10. When the handle has performed full reverse pivotal movement, the catch 37 will re-engage the first pin 29 to lock the first lever arm 24 in this position. It is also possible, however, either continuously or subsequently to pivot the handle 41 upwardly to continue rotation of the cam plate 35 beyond the position at which the projection 34 contacts the upper limb 31a. If this is done, the cam surface 38 continues to press down on the first pin 28 and so continues downward pivotal movement of the lever arm 24. The effect of this is to cause the upper limb 31a to engage the projection 34 and cause downward pivotal rotation of the second lever arm 25 to disengage the teeth 32 on this lever arm 25 from the associated slider block 20c. When this occurs, both blocks 20b,20c are released for sliding movement in their associated slots 18b,18c and the height of the frame 11 relative to the base 10 can be adjusted either by applying a downward pressure to the frame 11 or by removing such pressure to allow upward movement of the frame 11 under the action of the coil springs 23. When the frame 11 is at a required height, reverse rotation of the handle 41 initially allows the first lever arm 24 to rotate upwardly under the action of the spring 44 and then, as the lower limb 31b engages the projection 34, it also allows the first and second lever arms 24,25 to pivot upwardly together until their respective teeth 26,32 engage the associated slider blocks 20b,20c. When in this position, the front and rear pairs of Y-shaped linkages are locked and the height of the frame 11 is fixed relative to the base 10. Finally, the catch 37 engages the pin 29 to lock the first and second lever arms 24,25 in this position. In this way, a single mechanism controls both tilting and height of the frame 11 relative to the base 10. The frame 11 can be adjusted for tilt only or for height only or for tilt and height. It will be appreciated that the engagement between the first and second lever arms 24,25 and the associated slider blocks 20a,20b need not be by means of teeth; it could be by means of any suitable inter-engaging parts. In addition, the catch and pin 37,29 could be omitted, although its presence is desirable as a safety feature. Alternatively, it could be replaced by any suitable alternative catch mechanism. The latch members 27,33 are primarily provided so that the manufacturing costs of the arms are reduced - because the arms 24,25 themselves are identical. It will be appreciated, however, that the recess 30 and the limbs 31 could be formed integrally with the first arm 24 and the projection 34 formed integrally with the second arm 25. The cam plate 35 could be rotated in any way; for example, it could be rotated by a motor. The linkages 12a,12b,12c,12d need not be Y-shaped; they could be of any suitable arrangement that allows the appropriate adjustment and provides a member that can be locked and unlocked to lock and unlock the linkage. The first and second arms 24,25 are shown as pivoting but they could be mounted for rectilinear movement. The lost motion between the first and second arms 24,25 need not be by means of the recess 30 and the projection 34; it could be by any suitable means such as a pin and a slot.

Claims: A seat adjustment mechanism comprising a seat support frame (11) carried on a base (10) for movement relative thereto by a linkage, the linkage comprising first and second linkages (12b,12c), the first linkage (12b) being arranged towards a first end of the frame (11) and the second linkage (12c) being arranged towards a second end of the frame (11), a control mechanism (24,25,35) being provided which, in a first position, fixes the position of the frame (11) relative to the base (10) and which, in a further position, allows movement of both ends of the frame (11) relative to the base (10), characterized in that each linkage includes a block (20b,20c) slidable in an associated slot (18b,18c) in the frame (11) during said movement of the frame (11), the control mechanism (24,25,35), when in said first position, locks the blocks to the frame (11), the control mechanism (24,25,35) having a second position in which the control mechanism releases one of the blocks (20b) to allow movement of the associated end of the frame relative to the base (10), the control mechanism (24,25,35), in said further position, releasing both blocks (20b,20c) to allow said movement of said both ends of the frame (11) relative to the base (10). A mechanism according to claim 1 characterized in that the control mechanism (24,25,35) includes a lever arm (24,25) associated with each slot (18b,18c), each lever arm (24,25) being urged into engagement with the associated block (20b,20c) to prevent movement of the frame (11) relative to the base (10), the control mechanism also including a control member (35) operable selectively to disengage one or both of said lever arms (24,25) from the respective block (20a,20b). A mechanism according to claim 2 characterized in that each lever arm (24,25) is formed with teeth (26,32) for engagement with at least one tooth on the associated block (20b,20c). A mechanism according to claim 2 or claim 3 characterized in that each lever arm (24,25) is pivotally mounted on the frame 11. A mechanism according to any one of claims 2 to 4 wherein the control member (35) acts on one of said lever arms (24), a device (30,34) being provided between the lever arms (24,25) which transmits movement of one arm (24) to the other arm (25) only after said one lever arm (24) has moved away from engagement with the associated block (20b) and beyond the first disengaged position. A mechanism according to claim 5 characterized in that said one lever arm (24) includes a pair of stops (31a,31b) and the other arm (25) includes a projection (34) extending between said stops (31a,31b) and engaging one of said stops (31b) when both lever arms engage respective blocks (20b,20c) to prevent disengaging movement of said other lever arm (25), said one lever arm (24) being movable to disengage from the associated block (18b) with lost motion between said one lever arm (24) and the other lever arm (25) until the other of said stops (31a) engages the projection (34) when the one lever arm (24) is moving away from said first disengaged position to disengage the other of said lever arms (25) from the associated block (20c). A mechanism according to claim 5 or claim 6 characterized in that each lever arm (24,25) is formed by an elongate plate pivoted at one end to the frame (11), formed with said teeth (26,32) along an elongate side edge for engagement with a complementary formation on the associated block (20b,20c), said one lever arm (24) having a U-shaped recess (30) at the end thereof opposite the pivot, the limbs of said U-shaped recess (30) forming said stops (31a,31b), the other lever arm (25) having a projection (34) at the end thereof opposite the pivot, the projection (34) extending into said recess (30) and being engaged by said limbs (31a,31b) of said recess. A mechanism according to any one of claims 5 to 7 characterized in that the control member comprises a cam plate (35) pivoting between the first position in which the plate prevents movement of said one lever arm (24) from a position in which the lever arm (24) engages the associated block (20b) and a second position, said movement moving said one lever arm (24) to disengage said lever arm (24) from the associated block (20b). A mechanism according to claim 8 characterized in that the cam plate (35) includes a catch (37) which engages said one lever arm (24) in said first position of the cam plate (35) to prevent movement of said lever arm (24). A mechanism according to claim 9 characterized in that the cam plate (35) includes a cam surface (38) which, as the cam plate (35) is pivoted from said first position to said second position, engages a follower (28) on said one lever arm (24) to move said lever arm (24). A mechanism according to any one of claims 8 to 10 characterized in that the movement of the cam plate (35) from said first position to said second position moves initially said one lever arm (24) and then both said lever arms (24,25). A mechanism according to any one of claims 8 to 11 characterized in that the cam plate (35) is pivoted by manual operation of a control handle (41). A mechanism according to any one of claims 10 to 12 characterized in that each linkage comprises a pair of Y-shaped links (12a,12b,12c,12d) formed by a main link (17a,17b,17c,17d) pivotally connected at one end to the base (10) and having an end opposite to said one end slidable in an associated slot (18a,18b,18c,18d) in said frame, and by a second link (21a,21b,21c,21d) pivotally connected at one end to the associated main link (17a,17b,17c,17d) intermediate the ends thereof and pivotally connected to said frame (11) at an end opposite said one end, the Y-shaped links of each pair lying in parallel but spaced planes. A mechanism according to claim 13 characterized in that the main links (17a,17b,17c,17d) of each pair are interconnected by a rod (22a,22b). A mechanism according to claim 13 or claim 14 characterized in that spring means (23) act on each pair of Y-shaped links (12a,12b,12c,12d) to tend to close the angle between each main link (17a,17b,17c,17d) and the associated second link (21a,21b,21c,21d), so tending to maintain the frame (11) at a maximum spacing from said base (10).

Inventors: BLACKMORE DAVID CHARLES, BLACKMORE, DAVID CHARLES
Applicants: KAB SEATING LTD, KAB SEATING LIMITED
Application year: 1995
Main classification: B60N2
IPC codes: B60N2