GB2184770A

GB2184770A - Reclining seat actuator

Info

Publication number: GB2184770A
Application number: GB08624167A
Authority: GB
Inventors: James Hamilton Bowman; Roy Nightingale
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-10-25
Filing date: 1986-10-08
Publication date: 1987-07-01
Also published as: GB8526371D0; GB2184770B; GB8624167D0

Abstract

An actuator for controlling the angle of recline of the back of a seat, such as an aircraft seat comprises a hollow spindle 13 which slides telescopically in a sleeve member 1 against the action of a return spring which surrounds the sleeve member 1, but is not shown. The spindle 13 is locked to the sleeve member 1 in any one of a number of positions to hold the seat back in any one of a number of angular positions by a series of balls 20 which are loosely held in holes 19 in the spindle 13 and engage in any one of a number of grooves 10 in the sleeve member 1. The balls 20 are held in the groove 10 by a shoulder 24 on an actuating member 21. The balls can be released to allow the angle of the seat back to be adjusted by moving the member 21 to the left against the action of a spring 25 by means of a push rod 26. The rod 26 is moved by a Bowden cable and lever mechanism, not shown. The actuator is both lighter and less expensive to manufacture than hydraulic seat recline actuators which are commonly used in aircraft. Nevertheless it can be made to be of the required strength. <IMAGE>

Description

SPECIFICATION Reclining Seat Actuator This invention relates to actuators for reclining seats of the type which are commonly used in passenger vehicles such as aeroplanes, trains, and coaches, etc., and is particularly concerned with recline actuators suitable for use in aircraft.

At present the recline actuators used for aircraft seats are hydraulic and are required to withstand a compressive load of at least 3000 Ibs (1,361 kilograms). The actuator is mounted between the fixed frame of the seat and the pivoted seat back, and operates in response to pressing a button or lever, which is usually situated on an arm of the seat and is connected to the actuator by a Bowden cable, to allow the seat to be reclined orto return automatically to its upright position, and to lock the seat in position when the button or lever is released.

The present hydraulic actuators work well, but are expensive and there is a tendency for the hydraulic seals to fail, resulting in leakage of hydraulic fluid and necessitating replacement of the actuator.

The aim of the present invention is to avoid this problem by providing an actuator which is completely mechanical in its construction and operation. There have been many attempts at this but all have been unacceptable to the aircraft industry, either because they have not satisfied the strength requirements or because they have been too heavy. Weight is an important consideration in aircraft construction.

According to our invention, a reclining seat actuator comprises a sleeve member, a hollow spindle which is telescopically slidable in the sleeve member and is spring biased towards a fully extended position, a number of axially spaced locking recesses in a portion of the sleeve member around the spindle, a locking member which is carried by the spindle and is displaceable between a release position in which the spindle is free to slide in the sleeve member and a locking position in which the locking member projects into one of the locking recesses to lock the spindle axially relative to the sleeve member, and actuating means for causing movement of the locking member between its release and locking positions.

If the actuator is intended for use with aircraft seats, the actuator may be arranged to be fitted between the fixed frame of the seat and the pivoted seat back in the same way as the existing hydraulic actuators, and for this purpose one end of the actuator, preferably the free end of the sleeve member may be bifurcated and provided with a cross bore for pivotally connecting the actuator to the seat back, and the other end of the actuator, preferably the free end of the spindle, may have a screw-threaded portion by which the actuator can be fixed to the seat frame by suitable lock nuts.

Furthermore, the actuator may be arranged to have substantially the same fully extended and contracted lengths as the hydraulic actuator so that it will move the seat back between the same upright and fully reclined positions.

As will be appreciated therefore, a mechanical actuator in accordance with the invention can be constructed which can be fitted to an aircraft seat in place of the existing hydraulic actuator.

Furthermore, with the preferred construction described below, the mechanical actuator in accordance with the invention can be made lighter than the corresponding hydraulic actuator while being sufficiently strong to satisfy the stringent strength requirements laid down by the aircraft industry.

In use the actuating means will be arranged to release the locking member in response to operation of the recline button or lever of the seat, so that the spindle is free to slide in the sleeve member and allow the seat back to be adjusted in position. Rearward pressure on the seat back will recline the seat, compressing the actuator against the spring bias which naturally tends to extend it, and release of the pressure will allow the spring bias of the actuator to return the seat towards its upright position.When the recline button is released, the actuating means is arranged to move the locking member into its locking position, the member engaging in whichever of the locking recesses is located directly outwards of the locking member at the time, thus locking the seat in the desired position by preventing relative axial movement of the spindle and the sleeve member.

As will be appreciated, because the locking recesses are axially spaced apart, a little adjustment of the seat back may be necessary in order to bring a recess into alignment with the locking member before the locking can take place. Consequently with a mechanical actuator in accordance with the invention the seat can only be locked in any one of a series of discrete positions corresponding to the number and axial positions of the locking recesses, in contrast with existing hydraulic actuators which allow the seat to be locked anywhere between its fully upright and fully reclined positions.

Nevertheless the actuator in accordance with the invention should still provide a seat with a more than adequate range of locking positions. For example, in the construction described later with reference to the accompanying drawings, there are eight axially spaced locking recesses within the maximum contraction length of 1 inch (approximately 25 millimetres), which will enable the seat to be locked in its fully upright and fully reclined positions and in any one of six intermediate positions. In the case of current aircraft seats these locking positions will be spread over a distance of about8 inches, (200 millimetres) at the top of the seat back, which is the distance through which the top of the seat back is designed to move between the fully upright and fully reclined positions.

Preferably the locking member is a ball which is captive in a hole in the wall of the hollow spindle, the ball projecting radially outwards from the outer periphery of the spindle in its locking position, and projecting radially inwards of the inner periphery of the spindle in its release position.

Preferably the actuator has more than one locking member, preferably evenly distributed around the spindle and all being similar two each other and arranged to operate simultaneously and in the same way as each other.

Preferably each locking recess is formed by a peripheral groove extending around the inside of the sleeve member, and when balls are used as the locking members the groove preferably has an arcuate profile with a radius of curvature substantially corresponding to that of the balls. Each peripheral groove may be machined in the inner surface of the sleeve member. Alternatively it may be contained in a ring, either one for each groove or one containing all the grooves, which is inserted and retained axially in position within the sleeve member.

The actuating means preferably comprises an actuating member which is slidable within the hollow spindle and has a first portion for engaging and pushing the locking member or members outwards to the locking position and a second portion which is axially displaced from the first portion and which will permit the locking member or members to move inwards to release position, and means for moving the actuating member axially in the spindle.This moving means preferably comprises a rod which is connected to the actuating member and extends axially through the spindle to project from its free end (remote from the sleeve member) where it can be moved axially to move the actuating member by means connected to the seat recline button, and preferably also comprises a spring, preferably located within the spindle and acting directly on the actuating member, which biases the actuating member towards the locking position.

Preferably a damper is provided to damp the movement between the hollow spindle and the sleeve member. The damper may be in the form of a dashpot within the sleeve member at the end of the hollow spindle. The dashpot has a cylinder fixed on the end of the spindle and a piston with a rod which is fixed to a closed end of the sleeve member. The dashpot may contain either oil or air as the damping fluid.

The spring which biases the actuator to its fully extended position preferably comprises a coiled compression spring which is disposed around the sleeve member and which acts between a pair of axially spaced retainer cups which face each other and are fixed one around the sleeve member and the other around the spindle.

An example of a mechanical recline actuator in accordance with the invention will now be described with reference to the accompanying drawings, in which: Figure lisa side view of the actuator in its fully extending condition; Figure 2 is an axial section, to a larger scale, through the actuator in the same fully extended condition as shown in Figure 1 with the locking member in its locking position and illustrating the internal construction of the actuator but with an external spring and covering cups omitted; and, Figure 3 is an axial section corresponding to part of Figure 2, but showing the locking member in its release position.

The actuator comprises a cylindrical sleeve member 1 which is made of an aluminium alloy and which has a bore 2 extending axially from one end for about three quarters of the length of the member 1. The opposite end of the sleeve member is solid and is bifurcated as shown at 3, and has a transverse bore 4 extending through it and intersecting the bifurcation slot 3. The bore 2 has a first portion 5 leading from the open end of the sleeve member to an internal shoulder 6 which is located just over half way along the bore and from which a smaller diameter second portion 7 continues to the blind end 8 of the bore. Fitted within the first portion 5 of the bore is a row of eight identical individual steel locking rings 9, each having a circumferentially extending, radially inwardly facing, peripheral groove 10 of arcuate cross-section forming a locking recess.The locking rings 9, which may instead be formed integrally together as a single member, are clamped axially together between the shoulder 6 at one end an annular plug 11 at the other end, the plug 11 being screwed into an internally threaded portion 12 at the open end of the bore 2. The internal diameters of the locking rings 9 and the plug 11 are substantially the same, and is slightly less than that of the second portion 7 of the bore 2.

The actuator further comprises a hollow spindle 13 made of steel and having a cylindrical portion 14 which is slidable telescopically within the bore 2 of the sleeve member 1, and a smaller diameter externally screw-threaded portion 15 which extends from the cylindrical portion 14 at its end remote from the sleeve member and which contains an axially extending bore 16 communicating with the interior of the cylindrical portion 14. The length of the cylindrical portion 14 is approximately the same as that of the bore 2, and its external diameter is slightly less than that of the locking rings 9 and the end plug 11.The end of the cylindrical portion 14 within the bore 1 is closed by an end cap 17 providing an external flange 18 having a diameter which is greater than the internal diameter of the locking rings 9 so that the flange 18 and the end locking ring form co-operating stops which retain the spindle in the sleeve member.

Approximately halfway along its length the cylindrical portion 14 of the spindle has a ring of holes 19 extending through its wall. Each hole 19 houses a steel ball 20 having a diameter which is equal to or slightly greater than the sum of the wall thickness of the cylindrical portion 14 and the radial depth of the locking recesses 10. Two holes 19 and balls 20 are shown in diametricaily opposite positions in Figures 2 and 3 for simplicity and clarity, but there are five holes 19 containing the balls 20 evenly spaced apart circumferentially around the wall of the portion 14. The balls 20 are held captive within the holes 19 externally by the locking rings 9 and internally by a spool-like actuating member 21 which is made of steel and is slidably mounted within the cylindrical portion 14 in the region of the balls.

The actuating member 21 has at opposite ends a pair of guide portions 22 which are a close fit within the cylindrical portions 14, a reduced diameter central portion 23, and a step portion 24 between the central portion and one of the end portions.

Between the end cap 17 and the actuating member 21 the cylindrical portion of the spindle contains a compression spring 25 which biases the member 21 in a direction away from the end cap in order to bring the step portion 24 of the member 21 into engagement with the balls 20 so that the balls are forced radially outwards to project beyond the outer surface of the cylindrical portion 14 into one of the locking recesses 10, for example as shown in Figure 2, to lock the spindle 13 axially with respect to the sleeve member 1. At its end opposite the spring 25 the actuating member 21 is connected to (or is integral with) an actuating rod 26 which extends slidably through the bore 16 and projects from the free end of the threaded portion 15 of the spindle as can be seen in Figure 1.When the rod 26 is released, the step portion 24 is located in the position shown in Figure 3 by engagement of the shoulder between the step portion 24 and the guide portion 22 with the balls 20. This holds the member 21 as a whole and the rod 26 in the position shown in Figure 2. By pushing the projecting end of the rod 26 axially inwards, for example by means of a lever 28 operated by a Bowden cable 29 as indicated in dotted lines in Figure 1, the lever being mounted on the extreme end portion 30 of the spindle 13, the actuating member 21 is moved against the action of the spring 25 to displace the step portion 24 axially from the balls 20 and move the central portion 23 into the position radially inwards of the balls as shown in Figure 3.The diameter of the central portion 23 is such that the balls 20 are free to move radially inwards sufficiently to ciear the locking recesses 10 and allow relative axial movement between the sleeve member 1 and the spindle 13, while nevertheless retaining the balls in the holes 19.

The movement of the spindle 13 within and relative to the sleeve member 1 takes place under the partial restraint of a damper 31 within the closed left hand end of the sleeve member 1 as shown in Figure 2. The damper 31 is a dash pot comprising a cylinder 32 fixed on or integral with the end cap 17 and a piston 33. The piston 33 is fixed to the sleeve member 1 by a piston rod 34 so that it slides in the cylinder 32 as the spindle 15 slides in the sleeve member 1.

The piston rod 34 passes through a seal 35 fixed at the end of the cylinder 32 by a plug 35a which is held in position by a cap 35b, which is screwed on to the end of the cylinder 32 and the piston is sealed in the cylinder by an O-ring 36. The cylinder 32 contains either oil or air as a damping fluid, depending upon the magnitude of the damping required and the piston 33 has two restricted ports 37 through which the fluid flows to damp the movement of the piston 33 in the usual dashpot manner.

The sleeve member 1 and the spindle 13 are biased apart to the fully extended position of the actuator shown in Figure 2 by means of a coiled compression spring 38 located around the sleeve member 1 and acting between a pair of spring retainer cups 40 and 41 which, as shown in Figure 1, are mounted facing each other co-axially on the sleeve member 1 and the spindle 13 respectively.

The cup 40 abuts an annular external shoulder 42 on the sleeve member 1 either directly or through a spacer 43 as shown in Figure 1, and the cup 41 abuts a retaining nut 44which is screwed onto and locked in position on the threaded portion 15 of the spindle.

In operation therefore, the natural rest position of the actuator is as shown in Figures 1 and 2, i.e. with the spindle 13 and the sleeve member 1 locked axially relative to each other in the fully extended position of the actuator, which corresponds to the fully upright position of the seat. When the seat is to be reclined the operating button is pressed, causing the Bowden cable 29 and the lever 28 to move the actuating rod 26 and with it the actuating member 21 against the spring 25 and release the balls 20 from the end locking recess 10. The sleeve member 1 and the spindle 13 are then able to slide axially together as the seat is reclined against the action of the spring 38. When the desired seat position is reached the recline button is released, whereupon the spring 25 immediately moves the actuating member 21 back to the locking position where the step portion 24 forces the balls 20 radially outwards into whichever of the locking recesses 10 is positioned around the balls. The sleeve member 1 and the spindle 13 are thereupon once again locked axially relative to each other and the seat is thereby locked in the selected reclined position. When the seat is to be returned to its upright position the operating button is again pressed to release the balls 20 from the locking recess, and the seat is allowed to return to the upright position under the action of the return spring 38 moving the actuator back to the fully extended position.

Claims

1. A reclining seat actuator comprising a sleeve member, a hollow spindle which is telescopically slidable in the sleeve member and is spring biased towards a fully extended position, a number of axially spaced locking recesses in a portion of the sleeve member around the spindle, a locking member which is carried by the spindle and is displaceable between a release position in which the spindle is free to slide in the sleeve member and a locking position in which the locking member projects into one of the locking recesses to lock the spindle axially relative to the sleeve member, and actuating means for causing the movement of the locking member between its release and locking positions.

2. An actuator according to Claim 1 in which the locking member is a ball which is captive in a hole in the wall of the hollow spindle, the ball projecting radially outwards from the outer periphery of the spindle in its locking position and projecting radially inwards of the inner periphery of the spindle in its release position.

3. An actuator according to Claim 1 or Claim 2 in which there are a plurality of locking members evenly distributed around the spindle and all of which are similar to each other and are arranged to operate simultaneously and in the same way as each other.

4. An actuator according to Claim 3 in which each locking recess is formed buy a peripheral groove extending around the inside of the sleeve member.

5. An actuator according to Claim 4when dependent on Claim 2, in which the groove has an arcuate profile with a radius of curvature substantially corresponding to that of the balls.

6. An actuator according to Claim 4 or Claim 5, in which each groove is formed in a ring, a plurality of the rings being inserted and retained axially in position within the sleeve member.

7. An actuator according to any one of the preceding Claims, in which the actuating means comprises an actuating member which is slidable within the hollow spindle and has a first portion for engaging and pushing the locking member or members outwards to the locking position and a second portion which is axially displaced from the first portion and which permits the locking member or members to move inwards to the release position, and means for moving the actuating member axially in the spindle.

8. An actuator according to Claim 7 in which the moving means comprises a rod which is connected to the actuating member and extends axially through the spindle to project from the end of the spindle remote from the sleeve member.

9. An actuator according to Claim 8 in which the moving means further comprises a spring located within the spindle and acting directly on the actuating member, the spring biasing the actuating member towards the locking position.

10. An actuator according to any one of the preceding Claims, in which a damper is provided to damp the movement between the hollow spindle and the sleeve member.

11. An actuator according to Claim 10, in which the damper is in the form of a dash pot within the sleeve member at the end of the hollow spindle.

12. An actuator according to Claim 11 in which the dashport has a cylinder fixed on the end of the spindle and a piston with a rod which is fixed to a closed end of the sleeve member.

13. An actuator according to any one of the preceding Claims, which is intended for use with a reclining seat, the actuator being arranged to be fitted between a fixed frame of the seat and a pivoted seat back, wherein the free end of the sleeve member is bifurcated and provided with a cross bore for pivotally connecting the actuator to the seat back and the free end of the spindle has a screw threaded portion by which the actuator can be fixed to the seat frame by lock nuts.

13. An actuator according to any one of the preceding Claims in which the hollow spindle is spring biased towards a fully extended position by a coiled compression spring, which is disposed around the sleeve member and which acts between a pair of axially spaced retainer cups which face each other and are fixed one around the sleeve member and the other around the spindle.

14. An actuator according to any one of the preceding Claims, which is intended for use with reclining seats, the actuator being arranged to be fitted between a fixed frame of the seat and a pivoted seat back, wherein the free end of the sleeve member is bifurcated and provided with a crossbore for pivotally connecting the actuator to the seat back and the free end of the spindle has a screwthreaded portion by which the actuator can be fixed to the seat frame by lock nuts.

15. An actuator according to Claim 1, substantially as described with reference to the accompanying drawings.

Amendments to the claims have been filed, and have the following effect: Claims 1 and 7 above have been deleted or textually amended.

New or textually amended claims have been filed as follows: Claims 8 to 13 and 15 above have been renumbered as 7 to 12 and 14 and their appendancies corrected.

1. A reclining seat actuator comprising a sleeve member, a hollow spindle which is telescopically slidable in the sleeve member and is spring biased towards a fully extended position, a number of axially spaced locking recesses in a portion of the sleeve member around the spindle, a locking member which is carried by the spindle and is displaceable between a release position in which the spindle is free to slide in the sleeve member and a locking position in which the locking member projects into one of the locking recesses to lock the spindle axially relative to the sleeve member, and actuating means for causing the movement of the locking member between its release and locking positions, the actuating means comprising an actuating member which is axially slidable within the hollow spindle and has a first portion for engaging and pushing the locking member or members radially outwards to the locking position and a second portion which is axially displaced from the first portion and which permits the locking member or members to move radially inwards to the release position, and means for moving the actuating member axially in the spindle, movement of the actuating member within the spindle in the direction of extension of the spindle from the sleeve member causing the first portion to engage the locking member or members and push them radially outwards and movement in an opposite direction causing the second portion to permit the locking member or members to move radially inwards.