AU744144B3 - Improved seat arrangement - Google Patents

Description

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AUSTRALIA

Patents Act 1990 COMPLETE SPECIFICATION STANDARD PATENT Applicant(s): G AND J LEWIS ENTERPRISES PTY LTD A.C.N. 002 263 121 Invention Title: IMPROVED SEAT ARRANGEMENT The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 IMPROVED SEAT ARRANGEMENT Field of Invention The present invention relates to a seat arrangement and in particular to a seat arrangement which is movable between two operational states.

Background of Invention Seat arrangements with two or more operational states are known. For example, one type of seat arrangement in a first operational state provides a seat having a seat back and a seat base, the seat back extending at an angle with respect to the seat base so that a person can sit on the seat base and be supported by the seat back in the normal sitting position. In a second operational state, the seat back and the seat base are repositioned relative to each other to provide a substantially flat surface, the seat back and seat base extending in substantially the same plane. This arrangement can be used as a stretcher, for example. Such "stretcher seats" double as "normal" seats and stretchers depending on requirements. They may be useful in ambulances, medical aircraft, and generally any vehicle which requires the versatility of a seat which can act as a normal seat and also provide a flat surface in the event of need.

One problem with the prior art arrangements of this type, is that when the seat is in the normal seat operational state, if a large load is provided against the seat back, it may move or fold over towards the seat base and/or second operational state. In the event of an accident, when the seat mounts a seat belt, such a large load may be applied that the seat belt may be rendered ineffective because of relative movements of the seat back and seat base, resulting in injury to the seat occupant.

In prior art seat arrangements of this type, the seat back is attached to the seat base by a pair of pivot arms respective first ends of which attach to the sides of the 3 seat back and respective second ends of which are pivotably attached to the seat base. A shaft runs across the seat base between each of the pivot points, joining the pivot arms together. The pivot arms operate by pivoting between a first position, in which the seat is in a first operational state, in which a person is supported in use in a seated position, and a second position, in which the seat is in a second operational state, in which a person is supported in use in a lying position. To maintain the pivot arms in the first and second operational states, a cam is welded to the shaft which joins the pivot arms at the pivot point. This cam engages, in the first and second positions, with a locking pin, which holds the pivot arms in position. A problem with this prior art arrangement is that a large load applied to the seat back by, for example, a sash seat belt during a collision, can overcome the holding force of the locking pin and cam arrangement, causing the pivot arms to move from the first towards the second position, which can result in injury.

A further problem is that, even if the holding force of the locking pin and cam mechanism is not overcome, there is relatively little support for the seat back and the seat back can collapse forwardly, again resulting in a possible accident.

Note that in the prior art seat, in order to improve the holding capability of the pin, cam and shaft arrangement, the arrangement has to be made very heavy, and even then it may not hold high loads. With such a heavy arrangement, the entire seat is cumbersome.

Summary of Invention The present invention provides a seat arrangement, comprising a seat base, a seat back,-and a pivot arm joining the seat base and back and being pivotable about a pivot point between a first position in which the seat 4 back and the seat base are in a first operational state, in which a person is supported in use in a sitting position, and a second position in which the seat back and the seat base are in a second operational state, in which a person is supported in use in a lying position, and wherein, in the first position, a first portion of the pivot arm extends to abut a portion of the seat back to resist forward motion of the seat back under load.

Preferably, the portion of the seat back which is abutted by the pivot arm when the seat back is under load is a projecting portion, and is preferably a projecting boss which extends from the side of the seat back.

Preferably, there are a pair of pivot arms, one mounted on either side of the seat base and seat back.

Preferably, there are a corresponding pair of projecting bosses which act together with respective portions of the pair of pivot arms to resist forward motion of the seat back under load.

The present invention preferably has the advantage that when the seat arrangement is in the first operational state, if a load is applied forwardly to the seat back, such as may occur during an accident or a collision (the load may be applied through a seat belt which is mounted to the seat arrangement and worn by a seat occupant), the pivot arm will abut the seat back preventing forward motion of the seat back beyond the point where the pivot arm abuts the seat back. This resists the seat back collapsing during collision and causing serious injury. A seat back recliner mounting may be provided which, under normal circumstances, maintains the (adjusted) angle of the seat back relative to the seat base. Under load conditions, however, the recliner mechanism may not be strong enough to resist motion of the seat belt relative to the base, and prevention of forward motion is assisted by the pivot arm portion abutting to the seat back.

Brief Description of Drawings Features and advantages of the present invention will become apparent from the following description of an embodiment thereof, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view from above and one side of a seat arrangement in accordance with an embodiment of the present invention, illustrated in a first operational state; Fig. 2 is a view from the side of the seat arrangement of Fig. 1; Fig. 3 is a plan view of the seat arrangement of Fig.

1; Fig. 4 is a view from the side of the seat arrangement of Fig. 1 illustrated in a second operational state, and Fig. 5 is a detail on A of Fig. 1.

Description of Preferred Embodiment Referring to the drawings, a seat arrangement 1 is illustrated, which comprises a seat base 2 and a seat back 3. In this embodiment, the seat base 2 is formed from a rectangular section U-shaped bar 4. A pair of locking mechanism mounting tubes 5, 6 extend forwardly under the arms of the of the frame 4. A seat back 1 is also formed from a rectangular cross-section U-shaped bar 7 joined at the open end of the by cross-bar 8. Note that, in operation, cushions would be provided on the seat base and the seat back 1 for the comfort of a seat occupant. The cushions are not shown in the drawings, for the purpose of clarity.

The seat back 3 and seat base 2 are joined by a pair of pivot arms 8, 9. In this example, the pivot arms 8, 9 comprise metal webbing members joining the seat back 3 and seat base 2.

Each pivot arm 8, 9 is mounted to the seat base by a pivot 10, 11 mounted through the respective locking 6 mechanism mounting tubes 5, 6. Further portions of the respective pivot arms 8, 9 mount recliner mechanisms 12, 13 which supports the seat back 3. The recliner mechanism 12, 13 is conventional and will not be described in any more detail herein.

The pivot arms 8 and 9 are joined together proximate the seat back by a lateral tube 14, which is mounted at its ends to the recliner mechanisms 12, 13.

In operation, the pivot arms 8, 9 are arranged to pivot about the pivots 10, 11 between a first position as shown in Fig. 1 and a second position as illustrated in Fig. 4. In the first position, the seat arrangement 1 is in a first operational state, in which in use a person is supported in a sitting position. In the second position, the seat arrangement is in a second operational state, in which a person is supported in use in a lying position.

A seat locking mechanism will now be described which enables the seat back and seat base to be locked and supported in both the first operational state and the second operational state.

The seat locking mechanism mounting tubes 5 and 6 mount a rear lateral support shaft 15 and a front lateral support shaft 16, by through holes through the respective locking mechanism mounting tubes 5, 6. The front lateral support shaft 16 extends across the under side of the seat base frame 4 at the front thereof, and the rear lateral support shaft 15 extends across the seat base frame 4 at the rear thereof. The ends 17, 18 of the front lateral support shaft extend through the locking mechanism mounting tubes 5, 6 to provide supporting mounts for the pivot arms 8, 9 when they are in the second position (Fig.

The ends 19, 20 of the rear lateral support shaft extend through the locking mechanism mounting tubes 5, 6 and provide supporting mounts for the pivot arms 8, 9 when in the first position. Recesses are provided in each pivot arm 8, 9 for receiving the supporting mounts 17, 18, 19, 20 in the first and second positions respectively.

7 The recesses are designated by reference numerals 21, 22 (pivot arm 8) and 23, 24 (pivot arm 9).

The front lateral support shaft 16 and rear lateral support shaft 15 are sturdy enough to support the pivot arms 8, 9 when a person is occupying the seat.

The locking mechanism also comprises a rear locking member 25 and a front locking member 26. The front 26 and rear 25 locking members are movable between an extended position in which they abut the respective pivot arms 8, 9, and a retracted position, in which they are removed from the pivot arms 8, 9. In the extended position, the locking members 25, 26 operate to lock the pivot arms 8, 9 in the respective first or second positions.

In more detail, each locking member comprises a pair of locking pins 27, 28 (locking member 26) and 29, (locking member 25). The respective pair of pins 27, 28 and 29, 30 are linked by linkages 31, 32. One portion of the linkage 32 of the locking member 25 is shown in more detail in Fig. 5. The respective pivot arms are provided with two lock holes, 35, 36 (pivot arm 8) and 37, 38 (pivot arm When the pivot arms 8, 9 are in the first position and the locking member 25 is in the extended position, the respective locking pins 29 and 30 extend into the locking holes 36, 37. When the pivot arms 8, 9 are in the second position, and the locking member 26 is in the extended position, the locking pins 27, 28 extend into the locking holes 38, 39.

The locking members 25, 26 are actuated by a lock actuator shaft 40 which extends front to rear of the seat base 2. The lock actuator shaft is mounted rotatably by brackets 41, 42, mounted to the under side of the respective front 16 and rear 15 lateral support shafts.

The lock actuator shaft 40 is sprung loaded by a spring 43 to maintain the locking members 25, 26 in the extended position. The locking pins and pivot arms are profiled so when the pivot arms are in both the first or the second positions, the pivot arms strike the pins, which move back 8 against the spring tension. When the pivot arms come into contact with the lateral shafts (which limit the amount of rotations by the arms), the locking pins come into alignment with the lock holes in the arms. The spring tension applied to the lock actuator shaft pushes the lock pins into the lock holes. The locking actuator shaft is mounted to the linkages 31, 32 in order to enable extension and retraction of the locking members on rotation of the lock actuator shaft as indicated by arrow A in Fig. 1. Note that a handle would be provided in use on the locking actuator shaft, but is not shown here for the purpose of clarity.

The locking mechanism therefore securely locks the seat arrangement in the first operational state or the second operational state and is simply operated to enable the pivot arms to be moved between the first and second positions.

Referring to Fig. 1, the seat arrangement is provided with seat belt mounting points 51, 52, 53. The location for the sash belt mounting 53, is on the seat back 3. In the event of an accident, such as a collision, a large load is applied to the seat back 3 through the seat belt sash mounting point 53. In conventional arrangements, if the recliner mechanism 12, 13 is not strong enough (which is usually the case), then the seat back can fold forwardly, resulting in injury to the seat occupant.

Further, in conventional arrangements of this seat type (which have a different locking mechanism locking the arrangement in the first operational and second operational states), the seat may in fact move towards the second operational state, also possibly resulting in injury to the seat occupant. In the present invention, the locking member 25 prevents the seat moving towards the second operational state. Further, the seat back frame 7 is provided with side plates 55, 56 which have bosses 57, 58 extending outwardly thereof. An extension portion 59, of each pivot arm 8, 9 extends upwardly to a position 9 past the bosses 57, 58. If the seat back 3 is under sufficient load to overcome the holding force provided by the recliner mechanism 12, 13 it may move forward until the bosses 57, 58 abut respective extension portions 59, 60 as most clearly shown in Fig. 2. These prevent further forward motion of the seat back and thus further reduce the chances of injury.

The extension portions of each of the pivot arm reach some way up the seat back past the seat back recliner mechanisms. This assists in resisting forward motion of the seat back under large loads.

Note that the front and lateral support shafts are threaded on each end to provide mounting points for a patient restraint harness when the seat arrangement is in the second operative state. The bosses on the seat back may also assist this purpose.

Note that the locking member actuator may be a cable instead of a shaft.

It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (3)

1. A seat arrangement, comprising a seat base, a seat back, and a pivot arm joining the seat base and back and being pivotable about a pivot point between a first position in which the seat back and the seat base are in a first operational state, in which a person is supported in use in a sitting position, and a second position in which the seat back and the seat base are in a second operational state, in which a person is supported in use in a lying position, and further comprising a locking arrangement including a first locking member which is arranged to extend to abut the pivot arm and lock it into the first position, and a second locking member which extends to abut the pivot arm and lock it into the second position, the first and second locking members being movable between a first extended position in which they extend to abut the pivot arm and a second, retracted position in which they are removed from the pivot arm.

2. A seat arrangement in accordance with claim 1, further comprising an actuating member, which is linked to both first and second locking members and is arranged to actuated them simultaneously.

3. A seat arrangement in accordance with claim 1 or claim 2, wherein the first portion of the pivot arm includes a receiving hole the locking members preferably arranged to fit into the receiving hole and pivot arm to fix the pivot arm in position. 41868 F