GB2313049A

GB2313049A - Vertical lift chair

Info

Publication number: GB2313049A
Application number: GB9709837A
Authority: GB
Inventors: Richard John Hale
Original assignee: SEMINAR COMPONENTS
Current assignee: SEMINAR COMPONENTS
Priority date: 1996-05-15
Filing date: 1997-05-15
Publication date: 1997-11-19
Anticipated expiration: 2017-05-15
Also published as: GB9709837D0; GB2313049B; GB9610119D0

Abstract

A base frame AB is provided with a moving carriage D to which a hinge plate N is attached. A further hinge plate P is attached to the chair mounting frame Q. Upper and lower hinge pintels GH and JK link the hinge plates N and P. Drive means is provided between drive clevis points LM. The base frame is linked to the pintel JK by a lever EF and bracket X (pivoted at F) such that, when the drive means is activated in the upward direction, the pintel JK (and GH) move in a circular path and the levers EF pull the sub-base carriage D forward, so that the chair frame Q rises with a substantially vertical movement with little or no forwards or backwards movement.

Description

Vertical Lift Chair Previous lift and reclining chairs use non-parallel hinge pintels to achieve a lifting and tilting motion.

Other art exists in the use of standard scissor lifts wherein parallel pintels are used to maintain the lifted surface parallel to the position from which it originally started whether it be horizontal or otherwise. A vertical lift chair using parallel pintels has been produced but, because of the circular motion of the pintels, the chair lifts in a vertical and backward direction. The effect of the backward motion is to place the centre of gravity of the seated person towards the rear, thus creating a potentially unstable and unsafe situation.

According to the invention there is provided a vertical lift mechanism for raising a chair frame with respect to a base frame and comprising an assembly incorporating a carriage slidably mounted on the base frame, means for connecting a drive motor between the carriage and the chair frame, a pintel pivotally connected respectively to the chair frame and part of the carriage, and a compensator arm pivotally connected between the base frame and a bracket extending from an intermediate location on the pintel.

The provision of the sliding carriage and the compensator linkage has the result that, as the chair frame is lifted by a drive motor (connected between the base frame and the chair frame) the lower end of the pintel, mounted onto the carriage, is caused to move forwards with the carriage which counteracts the tendency of the chair frame to move backwards. Consequently, by suitable design of the parts of the assembly, the chair frame can be caused to rise in a substantially vertical motion with little or no forwards or backwards movement.

Ideally an assembly (linking the base frame and the chair frame) will be situated to both sides of the chair frame and base frame structure. It is also preferred that a second pintel should be mounted pivotally between the chair frame and part of the carriage so as to lie parallel to the first pintel. This gives greater stability to the whole assembly.

Preferably the carriage will be slidably mounted between retaining bars to control motion of the carriage parallel to the base frame. It is also preferred that the assembly should include guides on the carriage and base frame to limit yawing of the assembly.

The invention may be performed in various ways and a preferred embodiment will now be described, by way of example, with reference to the accompanying drawings, in which Figure 1 is a side view of a vertical lift mechanism of this invention in a lowered state; and Figure 2 is a side view of the mechanism of Figure 1 in a raised state.

By connecting a pair of compensator levers EF to one or other of upper or lower lifting pintels GH or JK and to a base AB and mounting a pintel hinge plate N on a moving sub bNse carriage D, the chair user moves in a forward and backward direction during the vertical lift, hence maintaining the centre of gravity of the user and the lift system substantially within the base frame envelope.

The system comprises a base frame AB with a moving carriage D to which the hinge plate N is attached. A hinge plate P is attached to the chair mounting frame Q. Upper and lower hinge pintels GH and JK link the hinge plates N and P. (There is an identical set of parts N, P, GH and JR to each side of the chair assembly.) Drive means (not shown) is provided between drive clevis points LM. The base frame is linked to the one pair JK of the hinge pintels by levers EF and brackets X (pivoted at F) such that, when the drive means is activated in the upward direction, the pintel pair JK (and GH) move in a circular path and the levers EF pull the sub-base carriage D forward. When the drive means is activated in the downward direction the levers EF push the sub-base carriage D backwards to the original position.

The carriage D is driven between retaining bars so as to control the carriage motion parallel to the base. Further guides are used on the carriage D and base AB to prevent yawing (side to side motion) of the assembly.

The angles shown in the drawings comprise the angle (81) of the lower pintel JK to the horizontal in the down position, the angle (92) of the lower pintel JK to the horizonal in the up position, and the angle (83) of the compensator lever EF to the horizontal.

The position of the upper compensator hinge point F in the lowered position (Figure 1) is located on an axis that is drawn through the pintel hinge point K to an angle drawn to the vertical, equal to the sum of the lower pintel angle 81 (Figure 1) and half of the lift angle 62 (Figure 2). The movement of the carriage is then at a maximum achievable for a given drive means extension and the radius of rotation KF.

By varying the radius of rotation KF to produce the desired movement of the carriage in conjunction with the compensator drive angle 63, while at the same time modifying the length EF to produce the required carriage movement, the angle 83 can be kept to a minimum, thereby maintaining the lowest drive load required to move the carriage. Thus for a given load to move the carriage in the horizontal direction the load in EF and subsequently the drive means varies as the cosine of 83.

Claims

1. A vertical lift mechanism for raising a chair frame with respect to a base frame and comprising an assembly incorporating a carriage slidably mounted on the base frame, means for connecting a drive motor between the carriage and the chair frame, a pintel pivotally connected respectively to the chair frame and part of the carriage, and a compensator arm pivotally connected between the base frame and a bracket extending from an intermediate location on the pintel.

2. A mechanism according to Claim 1, wherein the assembly is situated to both sides of the chair frame and the base frame structure.

3. A mechanism according to Claim 1 or Claim 2, wherein a second pintel is mounted pivotally between the chair frame and part of the carriage so as to lie parallel to the first pintel.

4. A mechanism according to any one of Claims 1 to 3, wherein the carriage is slidably mounted between retaining bars.

5. A mechanism according to any one of Claims 1 to 4, including guides on the carriage and base frame to limit yawing of the assembly.

6. A vertical lift mechanism for a chair substantially as herein described with reference to the accompanying drawings.