APPARATUS FOR OPERATING A SLIDING DOOR MEMBER

Abstract: Apparatus for operating a sliding door member, the apparatus being movable between a first condition, in which the door member is closed, and a second condition, in which the door member is open, and comprising a pneumatic cylinder (2) having an actuating piston (6), a piston rod (7) and means to reduce the force applied to the piston rod (7) when approaching the first condition, such means comprising a slidable cage (4) sealingly sleeved between the cylinder (2) and the piston (6). In use when moving towards the first condition the closing force is provided initially by conjoined movement of the piston (6) and the cage (4), and finally by the piston (6) only.

Description: The invention relates to apparatus for operating a sliding door member. The invention has been developed primarily for application to suburban train doors and will be described with reference to this particular application. However, it will be appreciated that the invention is not limited to this particular field of use. Such train doors may be of the type comprising two planar door members disposed, in the closed position, in edge to edge abutment and which are slid apart in the same plane during opening. Each door member requires individual operating apparatus usually utilizing a push stroke to open, and a pull stroke to close. The requirements of suitable operating apparatus include the ability to lock the doors in the closed position whilst the train is in motion. Most importantly a "soft nose" closing stroke is also required, whereby the closing force is reduced over the last part of the stroke to prevent crushing people or objects that may be trapped between the closing doors. In most applications it is also advantageous that any locking device can be manually overridden to unlock the doors if the train air supply falls below a minimum safe running pressure. The "soft nose" stroking has been achieved by use of mechanical and air cushion springs, requiring a hollow piston rod to house such devices. However, such designs preclude the use of conventional latching methods. Patent Specification CH-A-569 887 discloses a sliding door operator with a piston mounted in a sliding hollow piston which has a sealing ring on its end face such that upon sliding to a closed position of a door, air is initially exhausted through an open port but when the sealing ring reaches the end of the cylinder it closes the open port and further sliding movement of the piston causes air to be exhausted through a throttled port. According to CH-A-569 887 there is provided an apparatus for operating a sliding door member, the apparatus being movable between a first condition, in which the door member is closed, and a second condition, in which the door member is open, and comprising a pneumatic cylinder having an actuating piston, a piston rod and means to reduce the force applied to the piston rod when approaching the first condition, such means comprising a slidable cage sealingly sleeved between the cylinder and the piston and effective such that in use when moving towards the first condition the force is provided initially by conjoined movement of the piston and the cage, and finally by the piston only with exhaust air from the cylinder being directed through a first port during conjoined movement of the piston and the cage and through a second port during movement of the piston only and the second port being more constricted than the first port so that the piston is cushioned as the apparatus approaches the first condition. According to the invention, said apparatus for operating a sliding dorr contains a first latching means to lock the apparatus in the first condition, the first latching means including a spear having a locking recess and a tapered leading portion, the spear being fixedly secured to the piston, a first passage to receive the spear, a second passage at least partially intersecting the first passage and having therein a pin and first biasing means applied to the pin so that as the spear moves along the first passage the tapered leading portion displaces the pin against the first biasing means which subsequently urges the pin back and into locking engagement with the locking recess; and independently operable manual delatching means, the manually operated delatching means including at least one third passage at least partially intersecting with the second passage and having therein a cable operated spool movable between an inoperable and an operable position, the spool in the operable position cooperating with the pin to disengage it from the spear thereby unlocking the latch, and the frictional resistance between the spool and the third passage in combination with the friction in the cable being larger than the biasing force of the first biasing means applied to the pin thereby maintaining the latch in the unlocked position after the cable is released with the spool being returnable to the inoperable position by application of high pressure air. The invention is diagrammatically illustrated by way of example in the accompanying drawings, in which:- Figure 1 is a schematic sectional side elevation of door operating apparatus according to the invention, shown in a condition where the door is partially open; Figure 2 is a view similar to Figure 1 but showing the "door closed" condition; Figure 3 is an enlarged detailed side elevation of a "soft nose" stroking device shown in Figure 1 in combination with a latching device; Figure 4 is a sectional end elevation taken generally on line 4 -4 of Figure 3; and Figure 5 is an enlarged fragmented side elevation of the "soft nose" stroking device as shown in Figure 3 having an adjustable needle valve in the second port. Referring initially to Figures 1 and 2, apparatus 1 for operation of a sliding door member includes a pneumatic cylinder 2 having a latching device 3 at one end. A soft nose cage 4 is disposed within the cylinder 2 to reduce the force at the end of the closing stroke. The cylinder 2 comprises a substantially tubular outer body shell 5 housing an annular piston 6 which is fixedly secured to a piston rod 7. The cage 4 is sealingly sleeved between the shell 5 and the piston and rod assembly, and is captive about the piston 6. Where appropriate, seals are provided as will be seen in more detail in Figures 3 to 5. The piston rod 7 extends axially from the cylinder 2 terminating at its end distal to the latching device 3, in a coupling (not shown) for attachment to a door member. A terminal block 9 is located at the end of the shell 5 and provides an air inlet port 10. A spear 11 extends from the piston rod 7 beyond the piston 6 and towards the latch 3. The end of the cylinder 2 adjacent the terminal block 9 will hereinafter be referred to as the 'head end' of the cylinder and the end adjacent the latch 3 will be termed the 'cap end'. The latch 3 includes a block 13 in which is provided a first passage 12. Arranged transverse to and intersecting the first passage is a second passage 14 which includes a locking pin 15. A first port 16 extends parallel to the first passage 12 providing an air flow passage from the cylinder to a second port 17. A restricted orifice 18 is provided at the intersection of the first passage with the second port 17. An exhaust flow control valve 19 (not shown) is connected to the second port 17 at a position 24. In use, the device 1 is attached to the door by means of a coupling and supported from trunnion type mountings. A constant air supply is directed to the inlet port 10 via a restrictor and a non return valve (not shown), to provide a constant pressure head to the head end of the cylinder so as to keep the doors closed. When the air supply is applied to the cap end of the piston 6, the resultant opening force becomes larger than the permanent closing force thereby causing the door to open. The cross sectional area of the piston rod is designed to be approximately half the cross sectional area of the bore of the cylinder 2 and the opening and closing forces are thus approximately equal. When the door is open, the piston 6 rests against an end cap 20 of the cage 4 which in turn rests against the terminal block 9. The "door open" signal is then removed thereby exhausting air pressure from the cap end of the cylinder 2. This allows the permanent air supply at the head end from the inlet port 10 to act simultaneously on the piston 6 and the annular face of the end cap 20. As the area of the annular face of the end cap 20 is larger than the area of the main piston 6 and is not directly connected to the door, the cage will have a tendency to want to lead and to carry the main piston 6 with it. The closing force in this initial part of the stroke (shown in Figure 1) is then the additional force on the face of the annular end cap 20 combined with the force on the main piston 6. When the cage 4 fully strokes up against the block 13 of the latching device 3, the main piston 6 is left to stroke the remaining distance from the end cap 20 to an opposite end cap 21 thus leaving only the minor (soft nose) force acting on the main piston 6 fully to close the door. As the spear 11 enters the latch 3, a tapered leading edge thereof displaces the locking pin 15 against a biasing force provided by either mechanical or pneumatic means 22. When the tapered portion of the spear has traversed the locking pin 15 the pin 15 snaps back up behind the spear 11 to trap it in a fully home position. At the moment the cage 4 fully strokes against the block 13 there is a momentary pause in the closing action, as the closing force changes from full force to soft nose force due to the difference in piston areas. The resisting force on the latch side of the piston is controlled by the exhaust flow control valve 19 which takes a split second to bleed off sufficient pressure for closing motion to continue. The bleed rate through the exhaust control valve 19 is adjusted to the larger primary piston volumetric displacement. If applied to the smaller secondary piston displacement this would allow the closing speed to increase in proportion to the ratio of the two piston areas. This would then cause the two doors to slam together in the last couple of inches of closure, a situation which is not considered favourable. In order to overcome this potential problem this embodiment introduces a secondary flow control over the length of the soft nose stroke. The principle of cutting off the main exhaust flow and directing it through an orifice (either fixed or adjustable by a needle valve) is used to cushion the closing stroke. Hitherto, cushioning in cylinders has been created by having a central cushion spear or sleeve on either or both sides of the piston the same length as the desired length of cushioning. When the cushion spear or sleeve enters the end plate of the cylinder it engages in a circular seal housing in the end plate and blocks the main exhaust port which is located behind the cushioned seal. The trapped volume of fluid is then vented through an orifice running into the main exhaust port. The disadvantage of this method in long length cushioning is that the end plate must be at least as long as the cushion spear or sleeve, thereby making the cylinder unnecessarily long. In order to eliminate this disadvantage, the embodiment shown uses the cage 4 to redirect the exhaust flow through a restricted orifice. When the cage 4 fully strokes against the block 13 the first or main exhaust port 16 is sealed. As the piston 6 continues its closing movement the exhaust flow is then forced through the orifice 18 before passing out through the exhaust flow control valve 19. The size of the orifice 18 is designed to be more restrictive than the flow control valve 19 and therefore controls the closing speed over the soft nose stroke allowing the primary piston to close rapidly with full closing force until the secondary piston takes over. This allows both a soft nose closing force and a slow speed final closure which hitherto was only achievable by electrical door closing mechanisms such as in lifts and entrance doors for control of air conditioning. Referring now to Figures 3 and 4 there is shown in more detail the soft nose closing and cushioning devices connected with the first embodiment of the latching means. Throughout the description corresponding reference numerals have been used to denote corresponding features. In this embodiment of the latch 3 the locking pin 15 is sealingly slidable within the second passage 14 with the aid of an o-ring 25 seated in a corresponding ring groove provided in the peripheral surface of the pin 15. A helical compression spring 22 is seated within a bore provided in the pin 15 so as to bias the pin toward locking engagement with the spear 11. The compression spring 22 is selected to be just strong enough consistently to overcome the friction between the o-ring seal 25 and the passage 14. The orifice 18 is located in the second port 17 adjacent the first passage 12 and below the intersection with the first or main exhaust port 16. Connected to the second port 17 is the exhaust flow control valve 19. Referring briefly to Figure 5 there is shown the same latch device with an alternative port configuration utilizing an adjustable needle valve 18A to replace the fixed orifice 18 shown in the previous figures. This embodiment is preferred as it enables adjustment of the degree of cushioning required and allows fine tuning of the system at installation. Adjustments may also be required to take into account other variations such as door weights and closing speeds. Referring again to Figures 3 and 4, the block 13 includes two third passages 27 which partially intersect with opposite sides of the second passage 14. Provided within each passage 27 is a spool 28 biassed by a compression spring (not shown) in an upward direction as viewed in Figure 4 and with a "Bowden Cable" 29 threaded through its centre and secured by a grub screw 30. One cable can be operated from an internal location in the train car and the other from an external location. They may be operated together or separately (which is the most likely possibility) without interfering with each other. Each spool 28 is sealed with o-rings 31 and 32, the o-ring 31 being considerably smaller in diameter than the o-ring 32. When either cable 29 is actuated the corresponding spool 28 is pulled down so that a spool shoulder 33 contacts the locking pin 15 and presses it out of engagement with the spear 11. The friction of the two o-rings 31 and 32 in their respective passages 27 in addition to the friction of the cable 29 in its outer cable sheath is larger than the net closing force of the compression spring. This allows the spool 28 and the locking pin 15 to remain depressed even after the cable actuator has been released. When compressed air is again admitted to the cap both of the spools 28 and the cables 29 are reset to the position shown in Figure 4 by the pneumatic force on the surface of the shoulder 33. The locking pin 15 may be disposed at right angles to the spear 11 or inclined thereto. Inclination of the spool pin 15 allows a larger component of the actual force directed to the spear 11 to be utilized to help open the latch, which is particularly useful when the device incorporates the soft nose cushioning mechanism which reduces the force of the closing stroke. There is a further advantage in tilting the spool axis in that if an attempt is made to force open the door, the resulting motion of the spear 11 creates a force component in line with the axis of the spool 15 which is directed upwardly forcing the spool 15 to lock even harder.

Claims: Apparatus for operating a sliding door member, the apparatus being movable between a first condition, in which the door member is closed, and a second condition, in which the door member is open, and comprising a pneumatic cylinder (2) having an actuating piston (6), a piston rod (7) and means to reduce the force applied to the piston rod (7) when approaching the first condition, such means comprising a slidable cage (4) sealingly sleeved between the cylinder (2) and the piston (6) and effective such that in use when moving towards the first condition the force is provided initially by conjoined movement of the piston (6) and the cage (4), and finally by the piston (6) only with exhaust air from the cylinder being directed through a first port (16) during conjoined movement of the piston (6) and the cage (4) and through a second port (17) during movement of the piston (6) only and the second port (17) being more constricted than the first port (16) so that the piston (6) is cushioned as the apparatus approaches the first condition; characterised by a first latching means (11, 15) to lock the apparatus in the first condition, the first latching means including a spear (11) having a locking recess and a tapered leading portion (39), the spear (11) being fixedly secured to the piston (6), a first passage (12) to receive the spear (11), a second passage (14) at least partially intersecting the first passage (12) and having therein a pin (15) and first biasing means (22) applied to the pin (15) so that as the spear (11) moves along the first passage (12) the tapered leading portion displaces the pin (15) against the first biasing means (22) which subsequently urges the pin back and into locking engagement with the locking recess; and independently operable manual delatching means (27, 28, 29), the manually operated delatching means including at least one third passage (27) at least partially intersecting with the second passage (14) and having therein a cable (29) operated spool (28) movable between an inoperable and an operable position, the spool (28) in the operable position cooperating with the pin (15) to disengage it from the spear (11) thereby unlocking the latch, and the frictional resistance between the spool (28) and the third passage (27) in combination with the friction in the cable (29) being larger than the biasing force of the first biasing means (22) applied to the pin (15) thereby maintaining the latch in the unlocked position after the cable (29) is released with the spool (28) being returnable to the inoperable position by application of high pressure air. Apparatus according to claim 1, wherein the second passage intersects the first passage at an angle of less than 90°.

Inventors: HIGGINS,GEORGE DOUGLAS, PROPSTING,JOHN RISBY
Applicants: PARKER HANNIFIN (AUSTRALIA) PTY LTD
Application year: 1990
Main classification: E05F15
IPC codes: F15B15, E05F15