GB2185781A - Compact door actuator - Google Patents

Abstract

A door actuator arrangement particularly suited for operating doors in locations where mounting space is very limited, such as for operating single doors adjacent the end wall of a passenger carrying rail car. All of the major components of the arrangement are maintained within the narrow doorway structure above the doorway and within bounds defined by structural members adjacent the doorway opening. The actuator fluid motor is located directly above the door and its piston output rod 3 is connected to the door by means of a cranked mechanism including a second rod 11 which lies alongside the fluid motor cylinder thus enabling the door to be closed when the main rod is retracted. The mechanism includes a resilient telescopic arrangement, in which the door is biased towards the closed position, which confers a limited push-back travel in the event that the door should encounter an obstruction during closing. <IMAGE>

Description

SPECIFICATION Compact door actuator The invention relates to a compact door actuator.

A door actuator of the present invention is particularly suitable for mounting in a vehicle door head frame immediately above the door itself and substantially within the width defined by the door post structural members.

This position is preferred particularly for long stroke pneumatic cylinder actuators operating externally hung sliding doors. It is desirable that an actuator should occupy as little overhead space as possible, and to make a minimum incursion on the surrounding structure. Thus, when compared with bi-parting door sets, it is more difficult to provide a limited "push-back" facility for a single door for releasing trapped limbs, clothing etc. For mechanical strength the actuator piston rod must be retracted when the doors are closed.

For safety the door should be locked automatically when closed.

It is an object of the present invention to provide an actuator with these features and which occupies a minimal space envelope in length and cross section.

According to the present invention there is provided a door actuator having an actuator cylinder, an actuator piston, and a composite actuator rod assembly comprising a main rod which is connected at one end to the actuator piston inside the cylinder and has an external end guided by means running along an elongate guide track parallel to the axis of the rod, a second rod connected at one end to the guided external end of the main rod so that it is carried parallel to and spaced apart from the main rod whereby, when the actuator is operated, the said second rod moves axially to describe a path alongside the actuator cylinder, and the second rod carries at its distal end means for attatchment to a door.

Preferably the second rod is also provided at its distal end with an axially spring loaded, telescopic member whereby to provide a door with a limited push-back travel.

The invention will now be described, by way of example only, with reference to the arrangement illustrated in the accompanying drawings, in which: Figure 1 shows a view of the actuator cylinder and the main and second rods, including details of the "push-back" arrangement.

Figure 2 illustrates a detailed view of the mounting of the actuator assembly above a doorway, and Figure 3 shows a general view of the assembly mounted above a single door.

Referring to the drawing in which in Fig. 1 there is shown a door actuator comprising a cylinder 1 having an end cap assembly 2 through which emerges, on the axis of the cylinder 1, a main actuator rod 3. The driven piston of the actuator is slideably housed within the cylinder 1, but is not shown in the drawing, and to this is attached one end of the main actuator rod 3. Figs. 2 and 3 show respectively diagrammatic section and elevation of equipment as described installed in a vehicle, Fig. 3 illustrating the "open" condition.

The detailed construction of the actuator cylinder, and also the manifold arrangement for ducting pneumatic pressure to opposite ends of the cylinder 1 to operate the actuator, are not shown in the drawing for clarity as these form no part of the present invention.

The main actuator rod 3 has an external end, generally indicated at 4, to which is rigidly attached and effectively a part of rod 3, a guide means 5 which is slideably engaged with an elongate guide track 6. The guide track 6 is mounted on a vehicle frame parallel to the axis of the main actuator rod 3 and placed as close to the trajectory of the end 4 of the actuator rod 3 as is possible.

The guide means 5 depends from the end 4 of the rod 3 and has fixed to it one end 7 of a second tubular rod 8. This second tubular rod carries within its other distal, end 9 a spring 10 urging outwardly to a fixed stop position a telescopic rod member 11 attached rigidly to a drive arm 12 by means of which the telescopic rod member 11, and through it, tubular rod 8 is attached to a door (not shown).

The second rod assembly 8 and 11 is unsupported except at its ends 7 and 13. The rod is arranged to lie alongside the actuator cylinder 1, as closely as possible without fouling, and in the particular arrangement being described is substantially parallel to the axis of the cylinder and of the main actuator rod 3.

In operation of the invention compressed air is ducted alternately to opposite ends of the actuator cylinder, as required, to either open or close a door to which the drive arm 12 is attached. In the position shown in the drawing the main actuator rod 3 is fully withdrawn, and corresponds to a door being in its closed position. The actuator piston (not shown) is also held at the remote end of cylinder 1 towards the left in the drawing, by retained operating air pressure within the cylinder admitted through a port (not shown) in end cap 2.

A mechanical "closed" lock (not shown) may also be provided.

When the door is to be opened the retained pressure in cylinder 1 is vented while pressure is admitted to the opposite end of the cylinder. Following release of any mechanical lock which may be fitted this drives the piston towards the right in the drawing and extends the main actuator rod 3 in a direction also towards the right in the drawing. The external end 4 of the rod 3 is guided by the guide means 5 which runs along the guide track 6 drawing with it the second rod 8. Thus, the only clear space required beyond the right hand end of the actuactor is that space which is permanently occupied by the guide track 6 and, in addition, the volume periodically swept by the guide means 5.

While it is of the essence of preventing other than axial loading of the piston rod 3 that the guide means 5 is rigidly affixed thereto, resilient means 14 may be incorporated in the fixing of tubular rod 8 at its end 7 to guide means 5. Telescopic rod 11 may be rigidly attached to drive arm 12 and be provided with limited angular and radial freedom within end 9 of tubular rod 8. These attachment means allow of minor misalignments between actuator and door in operation without imposition of adverse loadings in either on that account.

Spring 10 is pre-loaded in the position shown with sufficient force to urge rod 11 to the left (as drawn) so as to ensure positive abutment of door and door post (not shown) in the "closed" position. Should a passenger's limb or other object be trapped as a door closes, spring 10 is compressed as the door is obstructed and the actuator continues under air pressure to move towards the fully retracted "closed and locked" position. A lock may be of the form described in our co-pending British patent application No. 85 31 667.

Injury or damage having been prevented by the initial resilience of spring 10, the door may then be "pushed-back" a pre-determined distance 'A' to effect release, further compressing spring 10 so that the door is positively urged to the fully closed position immediately on removal of any obstruction. Resilient buffer members 15, 16 afford cushioning of impact loads which may arise during "push back" and return of rod member 11.

Diagrammatic part section Fig. 2 shows how the compact actuating equipment is containable within the restricted space between ceiling 17 and vehicle cantrail/roof structure 18. Drive arm 12, connected to the doorhead 9 through the doorway opening may be made short and desirably stiff.

Referring to Fig. 3 it will be appreciated that only items 3, 5, and 8, guided by item 6, extend beyond the doorway width during opening of the door. In the "closed" mode all major items lie within the doorway width with the exception of fixed guide member 6. Working parts may therefore be readily inspected or serviced through panels in the ceiling spanning the doorway opening.

Claims (9)

CLAIMS 1. A door actuator having an actuator cylinder, an actuator piston, and a composite actuator rod assembly comprising a main rod which is connected at one end to the actuator piston inside the cylinder and has an external end guided by means running along an elongate track parallel to the axis of the rod, and a second rod havng one end connected to said guided external end of the main rod and carrying at its distal end means for attachment to a door.According to the present invention there is provided a door actuator having an actuator cylinder, an actuatory piston, and a composite actuator rod assembly comprising a main rod which is connected at one end to the actuator piston inside the cylinder and has an external end guided by means running along an elongate track parallel to the axis of the rod, a second rod connected at one end to the guided external end of the main rod so that it is carried parallel to and spaced apart from the main rod whereby, when the actuator is operated, the said second rod moves axially to describe a path alongside the actuator cylinder, and the second rod carries at its distal end means for attachment to a door. 2. A door actuator as claimed in claim 1 wherein the second rod is also provided at its distal end with an axially spring loaded, telescopic member. 3. A door actuator substantially as described with reference to the accompanying drawings. CLAIMS New claims or amendments to claims filed on 14th Jan '87 Superseded claims 1-3 New or amended claims:- 1-9

1. A door actuator having an actuator cylinder, an actuator piston, and a composite actuator rod assembly comprising a main rod which is connected at one end to the actuator piston inside the cylinder and has an external end guided by means running along an elongate track parallel to the axis of the rod, a second rod connected at one end to the guided external end of the main rod so that it is carried parallel to and spaced apart from the main rod whereby, when the actuator is operated, the said second rod moves axially to describe a path alongside the actuator cylinder, and the second rod carries at its distal end means for attachment to a door.

2. A door actuator as claimed in claim 1 wherein the said second rod lies alongside the cylinder when the main piston rod is retracted.

3. A door actuator as claimed in either claim 1 or claim 2 wherein the second rod is coupled with the main rod by coupling means including a bracket which is guided by a track.

4. A door actuator as claimed in claim 3 wherein the coupling means further includes resilient means.

5. A door actuator as claimed in any preceding claim wherein the second rod includes a telescopic member.

6. A door actuator as claimed in claim 5 wherein the telescopic member is connected to the door.

7. A door actuator as claimed in either claim 5 or claim 6 wherein the telescopic member is biased towards the door closed position.

8. A door actuator as claimed in any one of claims 5 to 7 wherein the telescopic member may be pushed back a predetermined distance upon the door encountering an obstruction.

9. A door actuator substantially as described with reference to the accompanying drawings.