GB2046828A - Sliding door latching mechanisms - Google Patents

Abstract

In a bi-parting sliding door arrangement driven by a linear actuator (10, 11) provided with overtravel means (14), a stationary rotatable double-headed latch hook (24) is driven into positive engagement with latch blocks (20) on the doors in the closed position, by means of a latch striker (32) carried by the actuator drive rod (11) and which is brought into striking contact by actuator overtravel. <IMAGE>

Description

SPECIFICATION Improvements relating to latching mechanisms This invention relates to self-latching actuators especially but not exclusively for use with sliding door arrangements for rail vehicles.

In the field of sliding vehicle doors, particularly for rail vehicles, it is desirable and often mandatory, although not always so, that the doors shall be normally latched or locked when in the closed position. In prior art arrangements utilising long stroke linear actuators (e.g. an hydraulic or pneumatic piston and cylinder arrangement) latches, which engage automatically as the door closes, have been used to lock the doors in the closed position. However, such latches require separate unlatching actuation in order to permit the door to open and this has contributed to problems of cost, maintenance and reliability.

The present invention provides an automatic latch mechanism which obviates the need for either a separate latching or unlatching actuator. It operates only on complete closure of the door or doors, thereby allowing the door or doors to be forced open in the event of anything being trapped. It also prevents the door or doors being forced open once fully closed and yet the latch is automatically released immediately the door actuator is energised in a sense to open the door or doors.

The present invention may be utilised in applications other than in railway vehicles, it may be used in single doors as well as double or multiple door arrangements, and also it can be used to latch doors open.

According to the present invention there is provided a self-latching actuator for latching relatively movable members comprising actuator means for moving the relatively movable members between extreme positions, overtra vex means arranged to provide the actuator means with overtravel movement beyond one of the extreme positions, a plurality of cooperating latch members mounted on respective relatively movable members, the latch members being positively engageable in the extreme position to latch the movable members in fixed relationship, the arrangement being such that the latch members are urged into positive engagement by overtravel movement of the actuating means.

In one form of the invention, for latching closed two biparting doors, the actuator means is arranged to move the doors apart to open and together to close, a first latch member is mounted on a frame member adjacent the door aperture to be intermediate and interlocking with further latch members mounted on each door. Preferably the first member comprises a rotatable double-headed latch-hook me member and the further member latch blocks, each capable of being positively engaged with a respective hook formed on the latch-hook member. Furthermore, the latch-hook member is preferably biased towards the dis-engaged position but is urged into latching engagement with the further latch parts by means of a latch-striking member, movable with the opening/closing mechanism, bearing onto a co-operating part of the latch-head for the extent of the overtravel distance of the mechanism.

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 of which: Figures 1, 2 and 3 show in diagrammatic form a side elevation of the relevant parts of a bi-parting sliding door linear actuator drive and latching mechanism, and Figures 4, 5, 6 and 7 show detail views of the latching mechanism of a further embodiment.

Referring now to the drawing, Figs. 1, 2 and 3 show the latching mechanism and part of the linear actuator drive for a rail vehicle biparting sliding door arrangement viewed from inside the vehicle with the protective covers removed; Fig. 1 shows the left-side of the mechanism, Fig. 2, the centre, and Fig. 3, the right-side. In the position depicted in the drawings, the doors (not shown) are intermediate their fully open and fully closed positions.

The doors (not shown) are hung by means of hanger brackets (also not shown) from door hanger support plates 1, 2 (Figs. 1, 3, respectively) which extend the full width of the doors. Each support plate is mounted on roller carriages, only one of which, 3, 4, is shown for each plate respectively. The carriages run on rollers 5, 6 in roller tracks 7, 8 which extend from the extremities of the door opening towards the centre thereof where they are supported by a common centre bracket 9 (Fig.

2).

The doors are driven between their open and closed positions by means of a single long-stroke linear actuator mechanism comprising a cylinder 1 0 (Figs. 1, 2) containing a slidable piston (not shown) to which an actuator drive rod 11 (Figs. 2, 3) is connected. The actuator is pneumatically operated (hydraulic operation is also possible) and has a dooropen inlet port 1 2 at one end of cylinder 10 and door-close inlet port 1 3 at the other end, the ports 12, 1 3 are connected by respective pipes (not shown) to opposite sides of a bidirectional control valve (not shown) which directs pneumatic pressure from a source to the appropriate port 1 2 or 1 3 of the actuator cylinder 1 0.

The actuator cylinder 10 is mounted above the roller track 7 to the left of the centre of the arrangement facing right, that is, the actuator rod 11 extends towards the right and is connected via an overtravel coupling, generally indicated at 14, to a drive bracket 1 5 bolted to right-hand door support plate 2.

Synchronised reciprocal drive is transmitted to the left-hand door through an endless drive belt 1 6 passing over free pulleys (not shown) rotatably mounted at opposite extremities of the roller tracks 7, 8. The upper part of drive bracket 1 5 carries a belt clamp 1 7 which is clamped to the upper run of the drive belt 1 6.

A further drive bracket 1 8 bolted to the lefthand door support plate 1 (Fig. 1) also carries on a lower part thereof a belt clamp 1 9 which is clamped to the lower run of belt 1 6. Other arrangements are opposite-handed, i.e. the actuator 10 is mounted right of centre.The latching mechanism consists of: a first latch block 20 (Fig. 3) carried by a support plate 21 mounted on drive bracket 15 and positioned to follow a path parallel to and level with the longitudinal axis of the roller track 8; a second latch block 22 (Fig. 1) similarly carried by a support plate 23 mounted on drive bracket 18 and positioned to follow a path parallel to and level with the longitudinal axis of roller track 7; and a rotatable doublehooked latch-head 24 (Fig. 2) pivotally mounted on a pivot pin 25 carried by the roller track centre bracket 9. The latch-head 24 is formed with diagonally opposed arms 26, 27 which terminate in latch hooks 28, 29 respectively, and is biased in a clockwise (in the plane of the drawing) direction by a spring (not shown).

The arm 26 of the latch-head 24 is formed with a heel portion 30 provided with a rightwardly facing face 31 which may be struck by a latch striker 32 (Fig. 3) mounted on actuator rod 11, just inboard of the overtravel mechanism 14. The striker 32 is adjustable on a threaded portion 33 of rod 11 in order that it may be accurately positioned such that it just contacts the face 31 as the doors reach the fully closed position. The overtravel of actuator rod 11 and striker 32 then rotates latch-head 24 in an anti-clockwise direction causing the latch hooks 28, 29 to engage the latch blocks 22, 20 respectively. The amount of overtravel of the mechanism 14 is determined by width of the gap 34, as will now be described.

The overtravel mechanism 14 comprises an extension rod 35 screwed into the back of latch-striker 32 and which extends co-axially with the main actuator rod 11 to pass through a clearance hole 36 in the body of drive bracket 1 5. The extension rod 35 has an integral collar flange 37 positioned on the actuator side of drive bracket 1 5 so that one face of the flange 37 can be made to bear against the drive bracket 15, in recess 38 in Fig. 3, in order to effect a door opening movement. The rod 35 extends through hole 36 and carries at its outer end an inwardly facing cap 39 inside which is located concentrically with rod 35 an overtravel spring 40, normally in compression and bearing against the bracket 1 5 and the inside of the base of cap 39.Thus, when the actuating rod 11 is drawn into the actuating cylinder 10 to effect a door-closing movement, the drive is transmitted to bracket 1 5 through spring 40, cap 39 in contact with the bracket if the spring 40 is sufficiently compressed, or a combination of the two. At the end of a normal door-closing movement, if the door or doors are unobstructed, the spring 40 will be substantially uncompressed, thus the rod 11 will be capable of a short overtravel to compress the spring 40. The length of this overtravel is controlled by the spacing between the rim of cap 39 and bracket 15, that is, by the gap 34.The mechanism is initially adjusted so that striker 32 just contacts face 31 on the latch-head 24 before the actuator commences its overtravel, thus during the overtravel movement the latch-head 24 is rotated in an anti-clockwise direction (in the drawing).

In operation of the arrangement depicted in the drawing, the actuator drive is applied directly to the right-hand door through bracket 1 5 and indirectly through the drive belt 1 6 to bracket 18 on the left-hand door. Energisation of actuator 10 through pneumatic pressure to port 1 3 results in the doors moving towards each other to close onto the centre-line of the arrangement. In the closed position, buffers mounted on the doors abut door stops 41, 42 mounted on bracket 9, the positions of the stops being adjustable to permit correct positioning of the doors when closed. Subsequent overtravel of rod 11 rotating latch-head 24 moves the latch hooks 28, 29 into engagement with latch blocks 22, 20, respectively.

For as long as pneumatic pressure is maintained at port 13, latch-striker 32 will continue to urge the latch hooks into engagement with the latch blocks on each door drive bracket which, in turn, prevent the doors being forced open.

When the doors are to be opened, the first event in the opening sequence is the release of pressure at port 13, followed by the application of pressure at port 1 2. Immediately upon this release of pressure, the bias spring acting on latch-head 24, assisted by the overtravel mechanism spring 40 withdrawing latch-striker 32, rotates the latch-head out of engagement with the latch blocks thereby permitting the doors to be opened.

Since the latch-head 24 is released by striker 32 as soon as the holding pressure at port 1 3 is relaxed, in the event of a fault in, or failure of the pneumatic system, the latching mechanism will release the doors and, although the doors will not open, they could be forced apart. To enable the doors to be locked or latched shut in the absence of pneumatic pressure, a manual lock is built-in.

In the drawing, the manual lock comprises a lock arm 43 attached to shaft 44 pivotally mounted in the centre bracket 9. The arm and shaft may be rotated using a square-section drive key (not shown) inserted into the squaresection hole 45 formed on one end of the shaft 44, to engage the radial end of the arm 43 with a heel portion 46 formed on latchhead 24. The arm 43 is prevented from being rotated into the locked position until a plunger 47 is depressed, thus preventing accidental damage of the mechanism which would result if the doors were closed with the latch-head 24 in the locked position. The plunger 47 is slidably mounted for axial movement in a bore formed in the bracket 9 which intersects along a chord a further bore in which the lock arm shaft 44 is rotatably mounted.The range of movement of plunger 47 is limited by an enlarged head 48 at one end and a retaining clip 49 at the other, and it is normally held against the retaining clip 49 by a light co-axial spring 50 fitted under the head 48.

The shaft 44 has a notch formed at right angles to its axis which lies flush with the plunger bore wall when the lock arm 43 lies at the angle shown in the drawing. In its normal position, the plunger 47 lies over the notch on shaft 44 preventing rotation of the shaft. The plunger 47 has a notch formed at right angles to its axis which may be brought in to register with the wall of the bore of shaft 44 by depressing the plunger against the spring 50 bias, thus allowing the shaft 44 to be turned to the lock position.

A further safety feature of the arrangement comprises a microswitch 51 (Fig. 2), the contacts of which are switched by the action of latch-head 28 depressing the switch actuator arm indicated at 52 just as the head engages with its respective latch block 22 (Fig. 1). This microswitch may be connected into a doorslocked indicator circuit or, as often preferred, into a traction motor control circuit to inhibit the application of traction drive while the door is in an unlatched condition.

The above arrangement may be adapted for operation of a single sliding door. Such an arrangement essentially comprises the same actuating means as driving the right-hand door, but without the drive belt transmission, to a further door and a single-headed latch mechanism which is otherwise operated in the same manner as that described above.

A further embodiment of a bi-parting sliding door mechanism according to the invention is illustrated in Figs. 4, 5, 6 and 7 in which parts also common to the embodiment of Figs. 1, 2 and 3 are given the same references. In this embodiment the latching mechanism and manual lock are modified, basically by mounting latch blocks 20, 22 on springloaded arms 53, 54 thus dispensing with the need for a safety feature, such as the lock-out plunger 47, to guard against rotation of the manual lock arm 43 when the doors are open.

In the view of Fig. 4, certain members of the sliding door mechanism would, if shown in the drawing, obscure parts of the latching mechanism. These members have been omitted therefore, as an aid to clarity.

In Fig. 4, the latch head 24 secured to a spindle 25, is shown by the continuous line in the latch-engaged position with latch blocks 20, 22 engaged by latch hook 29, 28, respectively. The spring-loaded arms 53, 54 carrying the latch blocks 20, 22 are rotatably mounted on pivot pins 55, 56 respectively and biased towards their normal latching positions (shown by the continuous lines) by torsion springs 57, 58. The latch head 24 is also biased towards its latching position by torsion spring 59, visible in Fig. 5, but omitted for clarity from Fig. 4. The chain-link lines in Fig.

4 show deflected positions of latch arms 53, 54 and the normal unlatched position of latch head 24.

In normal use, the latching mechanism is operated as before, the latch arms 53, 54 are mounted on support plates 21, 23 attached to right-hand and left-hand (in the Fig. 4) door drive brackets (not shown) respectively. The right-hand drive bracket is connected via overtravel mechanism 1 4 to the actuator drive rod 11; the drive bracket is formed with two parallel flange members 60, 61 with axially aligned clearance holes therein through which the drive rod extension 35 extends perpendicularly to the plane of the flanges. A further flange member 62 carried by rod 35 is positioned between flanges 60, 61 and presses onto the inside face of one or the other of the flanges through rubber cushion pads 63, 64.

The normal door closing actuator drive force is exerted on the outside face of flange 61 through spring 40 while rubber pad 64 remains more-or-less in contact with the inside face. After the doors have reached their fully closed positions, the actuator rod 11 continues to move for the overtravel distance compressing spring 40 up to the position in which rubber pad 63 now bears against the inside face of flange 60. The rod extension 35 also carries a latch-operating arm 65 which supports a latch striker 66 which is brought into contact with a side face 67 of a latch-operating lever 68 also rigidly secured to the spindle 25 to move with latch-head 24. During the ensuing movement lever 68 is moved by striker 66, thus rotating latch-head 24 from the unengaged chain-line position into the engaged solid-line position in Fig. 4.

The latch-operating lever 68 and the latchhead 24 may be manually locked in the latchengaged position by further parts of the mechanism to be described below. If, for some reason, the latch mechanism is locked in the engaged position and the doors are open (i.e.

latch-head 24 is in the solid-line position in Fig. 4, but the latch blocks 20, 22 are not in position to be engaged by the latch hooks 29, 28) then, when the doors are next closed, the leading faces 69, 70 on latch blocks 20, 22 strike the faces 71, 72 on latch hooks 29, 28 respectively. Each pair of contacting faces 69, 71 and 70, 72 are complementarily cham fered so that the right-hand sprung latch block arm 53 is deflected downwardly and the left hand latch block arm 54 is deflected upwardly thus avoiding damage to the latching mecha nism. However, once the latch blocks have sprung back and have engaged with the latch hooks, the latch will not automatically disen gage unless it has been, or has become, unlocked in the meantime.

The manual lock mechanism is illustrated in and best described with reference to Figs. 6 and 7. The latch-operating lever 68 comprises a plate-like member rigidly secured to latch spindle 25. The lever 68 is connected to a crank 73 by means of a link rod 74, one end of which is rotatably mounted on the crank 73 by a crank pin 75 and the end of which carries a locking pin 76 working within a slot 77 formed in the lever 68. In Fig. 6, the lever 68 is shown in the latch-engaged position and the unlocked position of the lock arrangement is shown by continuous lines, in which the locking pin 76 occupies the hatched position, and the locked position is shown by the chainlines, in which pin 76 is unhatched.A normally tensioned spring 78 exerts a permanent pull on crank 73 which is movable overcentre, between the locked and unlocked positions illustrated, by means of a square-drive key (not shown) which can be inserted into a square hole purposely formed in one end of the crank spindle 79 to provide a manual lock. In the unlocked position, the lever 68 is free to move within the limits imposed by the range of possible movement of pin 76 relative to the slot 77. In the alternative locked position, pin 76 is held hard against one end of slot 77 preventing rotation of the lever 68 and consequently latch-head 24 into the unlatched position, i.e. represented by the chainlink line in Fig. 4.

As with the previously described arrangement, this second embodiment may be adapted for use in a single sliding door arrangement by merely omitting those parts essential only for movement and latching of one of the doors, e.g. the indirectly driven door.

It will also be readily appreciated that the invention is not solely limited to use with sliding doors moving in either a horizontal or vertical direction. The invention may also be adapted in straightforward manner for use with a power-operated hinged door or a slide and plug door providing the power-operated opening/closing mechansim can be provied with an overtravel facility to operate the latch mechanism.

Claims (20)

1. A self-latching actuator for latching relatively movable members comprising actuator means for moving the relatively movable members between extreme positions, overtravel means arranged to provide the actuator means with overtravel movement beyond one of the extreme positions, a plurality of cooperating latch members mounted on respectively relatively movable members, the latch members being positively engageable in the extreme position to latch the movable members in fixed relationship, the arrangement being such that the latch members are urged into positive engagement by overtravel movement of the actuating means.

2. A self-latching actuator according to Claim 1, wherein drive from the actuator means is transmitted to a movable member through a drive rod attached to the member by means of a compressible coupling such that overtravel movement is provided by compression of the coupling.

3. A self-latching actuator according to Claim 2, wherein in the compressible coupling, the drive rod is slideably engaged with the movable member for movement over a limited distance to compress opposing spring means.

4. A self-latching actuator according to Claim 2 or Claim 3, comprising latch-striking means carried by the actuator drive rod and arranged to contact a latch member at the commencement of overtravel movement and thus by means of which the latch members are urged into positive engagement.

5. A self-latching actuator according to Claim 4, wherein the latch-striking means is adjustably carried by the actuator drive rod.

6. A self-latching actuator according to any preceding claim, wherein the latch members comprise a latch block mounted on a first relatively movable member and single-headed latch-hook rotatably mounted on a further relatively movable member and adapted for positive engagement with the latch block.

7. A self-latching actuator according to any of Claims 1-5, wherein the latch members comprise a latch block mounted on a first movable member, a second latch block mounted on a second movable member and, a double-headed latch-hook rotatably mounted on a further movable member and adapted for simultaneous positive engagement with both latch blocks.

8. A self-latching actuator according to Claim 6 or 7, wherein the relatively movable members are adapted for sliding movement towards each other and the latch-hook is mounted for rotation about an axis perpendicular to the direction of sliding movement.

9. A self-latching actuator according to Claim 6, 7 or 8, wherein the latch-hook is biased towards the dis-engaged position.

10. A self-latching actuator according to any preceding claim, further comprising lock ing means for locking the latching means in positive engagement.

11. A self-latching actuator according to Claim 10, wherein the locking means is manually operable.

1 2. A self-latching actuator according to Claim 10 or 11, when dependent upon any of Claims 6, 7, 8 or 9, wherein the locking means comprises a member selectively engageable with the latch-hook to prevent disengagement of the latch members.

1 3. A sliding door arrangement including a self-latching actuator according to any of Claims 1 to 5, or Claim 6, or Claims 8 to 12 when dependent from Claim 6, wherein a first latch member is mounted on the sliding door and a second latch member is mounted on a fixed part adjacent the door aperture.

14. A sliding door arrangement including a self-latching actuator according to Claim 6 or Claims 8 to 1 2 when dependent from Claim 6, wherein the first relatively movable member comprises the door and the further member comprises a fixed part adjacent the door aperture.

1 5. A bi-parting sliding door arrangement including a self-latching actuator according to any of Claims 1 to 5, or Claim 7, or Claims 8 to 1 2 when dependent from Claim 7, wherein first and second latch members are mounted on respectively sliding doors and a further latch member is mounted on a fixed part adjacent the door aperture.

1 6. A bi-parting sliding door arrangement including a self-latching actuator according to Claim 7 or Claims 8 to 1 2 when dependent from Claim 7, wherein the first and second movable members comprise respective bi-parting sliding doors and the further movable member comprises a fixed part adjacent the door aperture.

1 7. Apparatus according to any preceding Claim, wherein the self-latching actuator is hydraulically operated

1 8. Apparatus according to any of Claims 1 to 16, wherein the self-latching actuator is pneumatically operated.

1 9. A self-latching actuator, substantially as hereinbefore described with reference to Figs. 1, 2 and 3.

20. A self-latching actuator, substantially as hereinbefore with reference to Figs. 4, 5, 6 and 7.