GB2054734A

GB2054734A - Pneumatic door actuators

Info

Publication number: GB2054734A
Application number: GB8020354A
Authority: GB
Original assignee: Wabco Fahrzeugbremsen GmbH
Current assignee: Wabco Fahrzeugbremsen GmbH
Priority date: 1979-06-27
Filing date: 1980-06-20
Publication date: 1981-02-18
Also published as: IT8067859A0; GB2054734B; FR2459865A1; AT381762B; ATA339380A; FR2459865B1; DE2925885C2; HU178878B; IT1128794B; DE2925885A1

Abstract

A pneumatic door actuator is arranged such that in a door closing and/or opening stroke, under the influence of air pressure acting on one side of a piston 2, air on the other side of the piston is displaced to atmosphere up to a first point where a first valve 11, 12 closes so that remaining air acts as a slowing down cushion up to a second point where a further valve 22, 23, 24 opens to allow the actuator to speed up again towards a final closing and locking position. <IMAGE>

Description

SPECIFICATION Pneumatic door actuators This invention relates to pneumatic door actuators for opening and closing doors and relates especially, but not exclusively, to actuators for operating spindie-mounted swing or folding doors.

In German OLS. 2062135, a swinging door operating mechanism is disclosed which is connected with swivel arms to a turning pillar. A compressed air cylinder is employed to actuate the pillar and the piston of this cylinder produces a turning moment via a lever arm fixed to the pillar.

A second air cylinder is also provided which operates to raise and lower the door to enable the door to be moved into and out of a locking position.

In an embodiment of a door actuating mechanism described in a further German OLS.

2606322, a compressed air cylinder for opening and closing a swinging is incorporated in the door pillar itself in order to economise on space.

Although not described therein, in such an arrangement, locking of the door, if included, would ordinarily require a separate locking system.

Design data sheets 422802 to 422808 (Europe Catalogue), published by the Applicants, show a number of such pneumatic door actuators.

In these actuators, the door movement is divided into two damped or throttled phases of motion, a relatively quick first phase is slowed down by an air throttling action to achieve a slower second phase, particularly towards the closed position of the door. As a result of throttling of the phases, the opening and closing times of the doors tend to be relatively long, typically several seconds.

An object of the present invention is to provide a pneumatic door actuator which enables the closing and opening of a door in a shorter time than has hitherto been provided by actuators such as referred to above and which may also provide the capability of moving the door actuating mechanism into a locked condition.

According to the present invention, there is provided a two-ended pneumatically operable door actuator including a bi-directionally operable piston assembly and cylinder arrangement with first means operable to divide the door closing and/or opening stroke of the piston into a first phase with a first velocity and a second phase with a second velocity which is slow in relation to the first velocity and wherein second means is provided operable during the second phase to initiate a third relatively faster phase.

In order that the invention may be more clearly understood and readily carried into effect, the same will be further described by way of example, with reference to the accompanying drawing in which:- Fig. 1 illustrates a longitudinal section of a door actuator in accordance with one embodiment of the invention and Fig. 2 illustrates a cross-section of one end of the cylinder of the actuator of Fig. 1.

Referring to Fig. 1 , the actuator includes a cylinder 1 which is closed at both ends and provided with a double-acting piston 2 with a piston rod 4 passing through one end 3. The rod 4 is linked, in operation, to a drive or door actuator mechanism for a door spindle. To either side of the piston 2 there are thus formed two chambers 5 and 6 the alternative pressurising and bleeding of which takes place from a suitable control valve, not shown. With reference to Fig. 2, the port 8 provides a control port for the application of fluid pressure to the chamber 5 through the end cover 3 and the port 9 (Fig. 1) provides a control port for the application of pressure to the chamber 6 via the other end cover 10.

An annular valve member 11 is sealingly slideable on the piston rod 4 to provide, in conjunction with an annular valve seating recess 12 formed on the inside of the cover 3, a first valve which becomes closed-off at a given position of the piston 2 when moving towards the closed position for the door. Engagement of the valve member 11 with the recess 1 2 thus closesoff the connection between the chamber 5 and the port 8 via the duct 7, as shown in Fig. 2. A spring 13 arranged between the valve member 11 and the piston 2 provides a given amount of lost motion between the valve member 11, when sliding along the piston rod 4, in relation to piston 2.

A bypass 14 with an adjustable throttle device 1 5 provides for a throttleable connection between the chamber 5 and the port 8 even when the valve member 11 is in engagement with the recess 12.

Referring now to the chamber 6 on the other side of the piston 2, an annular valve member 16 is provided which, in conjunction with a fixed annular valve seat 1 7, formed on the inside of the cover 10, provides a valve arrangement which opens and closes a connection between the chamber 6 and the control port 9 dependent upon the position of the piston 2. The valve member 1 6 is carried on a plunger 1 8 which is freely axially movable in an axial bore in the piston rod 4 and a spring 19 urges the plunger 1 8 leftwards to provide a given amount of lost motion for the valve member 1 6 in relation to the piston 2.A bypass 20 provided with an adjustable throttle device 21 provides a connection between the chamber 6 and the port 9 even when the valve member 1 6 is engaged with its seat 1 7. Referring again to the end cover 3, a tappet valve device with a valve member 23 and a valve seat 22 is arranged in a path between the chamber 6 and the port 8 and urged by a spring 25 into the closed position as shown. It further has an actuator rod 24 which extends into the chamber 5 to be engageable by the face 2a of the piston 2 on reaching a certain point in its travel towards the closed position of the door. On such engagement, the valve member 23 is unseated from the valve seat 22 to re-open a free communication for air from the chamber 5 to the port 8 via a passage 7a, as indicated in Fig. 2.The valve arrangement 22, 23 is arranged in a sealingly slideable bush mounted in the end cover 3, the position of which bush is governed by an eccentric adjustment device 26 which enables the position of the point of engagement of the piston face 2a with the actuator rod 24 to be precisely determined by manual adjustment from outside the actuator.

In operation of the actuator of Figs. 1 and 2, in the position of the piston 2 and actuator rod 4, as shown in Fig. 1, the actuator is in the door-open position. In order to move the door from the open position towards its closed position, compressed air is applied via the port 9 from the control valve, not shown, and this is of sufficient pressure to unseat the valve member 1 6 from its seat 1 7 against the force of the spring 1 9. The pressure which therefore builds-up in the chamber 6 urges the piston 2 and piston rod 4 rightwardly because, under these conditions, the chamber 5 is vented via the passage 7 and the control port 8 through the control valve arrangement. Rapid movement of the piston 2 is therefore effected in a first phase of motion towards the position at which the valve member 11 engages in its seat in the recess 12.

During subsequent motion, not only does the effect of the spring 13 begin to act but also the path for air from the chamber 5 through the port 8 is now restricted and can take place only via the throttling device 1 5. A second phase of motion is thus effective during which the adjustable throttle unit 1 5 brings about a reduction in the speed of travel of the piston 2 towards its closed position.

At a certain point, the door is at, or near, its fully closed condition and further travel of the piston 2 is required only to effect lifting or other actuation of the door mechanism to set it in its locked condition. At this point, the piston face 2a engages with the rod 24 to unseat the valve member 23 from its valve seat 22 thereby interrupting the second phase to give way to a third unrestricted phase of travel of the piston thereby enabling the aforementioned locking action to be effected.

In operation of the actuator for opening the door, air under pressure is applied at the port 8, the pressure at port 9 having been returned to atmospheric. The pressure at port 8 is applied via the duct 7 to the inside of the recess 12 and also via the passage 7a and the unseated valve 22, 23, the piston 2 therefore commences a first rapid opening movement phase, air in chamber 6 being vented via the valve seat 7 and the port 9. Upon engagement of the valve member 1 6 with the valve seat 17, the chamber 6 is vented only via the bypass path 20 with the adjustable throttle 21 and a second phase of reduced movement speed for the piston 2 is thereby produced towards the finally open position of the door.

If locking of the mechanism in the open position of the door is required, it is possible to install a tappet valve similar to the valve 22,23 in the end cover 10 of the double-acting cylinder to provide for a third less restricted phase of movement towards a finally open and locked position.

It will be appreciated from the foregoing that a tappet valve such as 22, 23 may be provided in accordance with the invention to introduce a third phase in the door closing stroke and/or the door closing stroke within the ambit of the present invention in accordance with door operator requirements.

By virtue of the invention, an optimum saving in space for a door closing system can be achieved through the provision of the third unrestricted motion phase of the door cylinder by which the door is brought into its locked setting. The door cylinder, in accordance with the invention, can be made relatively compact so that it can be fitted into the turning pillar of the door as a spindle drive.

Claims

1. A pneumatically operable door actuator including a two-ended bi-directionally operable piston assembly and cylinder arrangement with first means operable to divide the door closing and/or opening stroke of the piston into a first phase with a first velocity and a second phase with a second velocity which is slow relative to the first velocity and wherein third means is provided operable during the second phase to initiate a third phase which is faster relative to the second phase.

2. A pneumatically operable door actuator as claimed in Claim 1, wherein adjustment means are provided for adjusting the position of onset of the third phase.

3. A pneumatically operable door actuator as claimed in Claim 1 or 2, wherein for limiting the first phase of motion in either stroke, valve means is arranged movable with the piston, said valve means comprising a resiiiently biased slideable valve member carried by the piston and engageable with a seat at the facing end cover of the cylinder, said valve being arranged to close-off a flow path from the chamber contained between the piston and said respective end of the cylinder.

4. A pneumatically operable door actuator as claimed in Claim 3, including further valve means for determining the first fast phase of movement of the piston in the other stroke, comprising a valve member carried on a plunger spring-loaded in the piston rod and engageable with a valve seat provided at the other end cover of the cylinder closure of which valve seals-off a passage between the chamber formed between the piston and the other respective end of the cylinder.

5. A pneumatically operable door actuator as claimed in Claim 3, said valve member comprising a slideable annular valve member carried on a rod of the piston.

6. A pneumatically operable door actuator as claimed in Claim 3 or 5, said valve member or a further said valve member being carried by a spring-loaded plunger carried in the piston assembly.

7. A pneumatically operable door actuator as claimed in Claim 1, 2, 3 or 4, throttle means being provided in a bypass flow path from the, or each, respective chamber formed between the piston and the, or each, end of the cylinder.

8. A pneumatically operable door actuator as claimed in Claim 7, the, or each, throttle means being adjustable.

9. A pneumatically operable door actuator as claimed in Claim 7 or 8, including for initiation of the, or each, third fast travel phase, there are provided additional valve means operable by the piston for opening a fluid flow path or paths which bypass the throttle means.

10. A pneumatically operable door actuator as claimed in Claim 9, the said additional valve means comprising a spring-loaded valve with an operating rod extending out of the respective cylinder end towards the piston assembly.

11. A pneumatically operable door actuator as claimed in Claim 10, said additional valve means being carried in a sleeve which is adjustable towards and away from the piston assembly.

12. A pneumatically operable door actuator as claimed in Claim 11, adjustment means for the additional valve comprising a rotatable eccentric member operable from outside the actuator and engaging said sleeve.

13. A pneumatically operable door actuator, substantially as described herein with reference to Figs. 1 and 2 of the accompanying drawings.