GB2185518A - Door closure device - Google Patents

Abstract

A door closure device 13 e.g. for a roller shutter door 10 of a commercial vehicle, fire engine comprises a body 14 secured to the door 10 and a retaining member 16 secured to the door frame 11 or vice versa. A fastening member 18 is slidably mounted in the body 14 and has roller means in the form of a bearing 21 at its free end to engage member 16 a compression spring 19 biasing the member 18 outwardly. The member 16 has two oppositely inclined cam surfaces 25, 26 a part 27 of the lower cam surface 26 being engaged by the bearing 21 when the door 10 is closed. When door 10 is closed by pulling downwardly on flange 12 bearing comes into contact with upper cam surface 25 causing initial retraction of member 18 into body 13 and subsequent emission into door closed retaining position with the outer face of bearing 21 in contact with part 27. An upwardly directed force of not excessive magnitude causes bearing 21 to roll along surfaces 26, 25. Angles of inclination of surfaces 25, 26 may be substantially equal or differ. Retaining member may be plastics e.g. nylon. Separate or combined locking mechanism may be provided. <IMAGE>

Description

SPECIFICATION Door closure device This invention relates to door closure devices and has particularthough not exclusive application in relation to closure devices for roller shutter doors such as may be fitted to commercial vehicles, fire engines and the like.

Conventionally doors are retained in a closed position by means of at least one latch device being retained by retaining means, such as a recess in, our a retaining plate or protrusion attached to or integral with, the doorframe or like surrounding structure. In many cases it is desired that the door can be closed by simply pushing it into the closed position and the latch device move into its door retaining position without the operation of any push-button, handle, lever or key device. In orderto achieve such closure it is conventional for either the latch device or the door surrounding structure to have a cam surface to be engaged by the other during the door closing operation, such engagement causing movement of the latch device, against a biassing means, from the position it adopts when retaining the door in its closed position.If it is desired that such door may be opened by simply moving it from its closed position without the operation of any push-button handle, lever or key device it is known to provide a second cam surface on the latch device or the door sur rounding structure in opposed disposition to the first cam surface. However, unless very strong biassing means are used, such an arrangement does not pro vide thatthe door is securely retained in the closed position and in such cases it is possible for the door to open inadvertently,forexampleduetoagustof wind. In the case of doors of vehicles, movement of the vehicle cou Id cause inadvertent opening of a door when retained closed in this latter manner.If strong biassing means are used in such an arrangement it is often very difficult to open the door.

In consequence when it is required that inad vertent opening of a door is prevented, or the risk of such opening be reduced to a minimum, such second cam surface is not provided. In that case a push-button, handle, lever or key operating device is provided which is operable to retract the latch device from the recess in, orfrom contact with a latch plate or protrusion on, the door surrounding structure in orderthat the door can be opened. However, the provision of such operating devices increases the cost of the door closing means and can increase the risk of jamming or malfunction of such means,forexample due to lack of lubrication, dirt ingress or the like.In addition, in certain cases such as doors of fire engines, the operation of push-button handles, levers or key operated devices can be inconvenient and add undesirably to the time taken in opening the door.

It is an object of the present invention to provide a door closure device which avoids or overcomes to a substantial extentthe abovementioned disadvantages.

The invention provides a door closure device comprising a body, a latch member mounted in said body so as to be movable relative thereto in a predetermined direction between door retaining and door releasing positions, a latch retaining member having two cam surfaces engageable by said latch member and oppositely inclined relative to said predetermined direction, and roller means mounted on one of said latch members and said retaining member and engaged by the other when said closure device is in said door retaining positions.

Preferably said body is adapted to be mounted on a door and said retaining member is adapted to be mounted on a door surrounding structure. Preferably said latch member is resiliently biassed towards said door retaining position.

The latch member may comprise a rod slidably mounted in said body, and a compression spring may be mounted around said rod to engage said body and a stop means provided on said rod.

Said roller means may comprise a bearing and may be mounted on a free end of said latch member disposed outside said body.

Afirst portion of one of said cam surfaces may include a point of contact of said cam surface with said roller means when said latch member is in its door retaining position, and may be less inclined relative to said predetermined direction than the remainder of said one cam surface. Said first portion may be curved, and said remainder may be rectilinear and substantiallytangential thereto.

One embodiment of door closure device in accordance with the invention will now be described with reference to the accompanying drawing in which Figure lisa part front elevation with the retaining member in section on line A-A of Figure 3, Figure2 is a view from beneath in section on line B-B of Figure 1, Figure 3 is a side elevation of the retaining member of Figure 1, and Figures 4and 5are front and rear elevations of the retaining member of Figure 3.

Referring now to Figures 1 and 2 there is shown a door 10 in a closed position in a doorframe 11. The door 10 in the embodiment shown is a rollershutter door which is closed by being pulled downwardly, a flange 12 attached to the door 10 serving as a doorpull for this purpose. Attached by means of rivets 15 to each bottom corner of the door 10 (only one corner being shown in Figures 1 and 2) is a body 14 of a door closure device 13, and attached to the door frame 11 adjacent each bottom corner thereof is a retaining member 16.

The body 13 has a housing part 17 in which is slidably received a latch member 18. A compression spring 19is mounted aroundthe latch member18 within the housing part 17 and one end of spring 19 engages the housing part 17 whilst the other end of spring 19 engages a stop pin 20 attached to the latch member 18. The latch member 18 is thereby resiliently biassed axially of itself to extend with one end disposed outwardlyofthe housing part17. Onthe free end of the latch member 18 disposed outwardly of the housing part 17 is mounted roller means in the form of a bearing 21 so that the outer race thereof is freely rotatable.

The retaining member 16 is a moulded block of a plastics material, for example nylon, although other materials may be used if preferred, and is shown in detail in Figures 3 to 5. The retaining member16 comprises an attachment part 22 having apertures 23 therein whereby it may be attached to the doorframe 11. The retaining member 16 also comprises an operating part24which is formed having two cam surfaces 25,26, which are oppositely inclined relative to the direction of sliding of the latch member 18. The angles of inclination of the cam surfaces 25,26 to the direction of sliding of latch member 18may be substantially equal as shown in the figures, or may differ from each other if preferred.For example the cam surface 25 may be inclined to the direction of sliding of the latch member 18 at a greater angle than is cam surface 26 so as to minimise the impulsive force required to close the door 10 whilst maintaining satisfactory retention of the door 10 in its closed position. To ensure the latter, whilst providing that an excessive force is not required to open the door 10, the first part 27 of the cam surface 26 is inclined to the direction of sliding of latch member 18 at a lesser angle than is the remainder of cam surface 26, and preferably is curved as shown with the remainder of cam surface 26 being rectilinear and tangential to the curved part 27.

The door 10 is closed by pulling downwardly on flange 12 that the door 10 slides downwardly within frame 11.The bearing 21 comes into contact with upper cam surface 25 and further downward movement of door 10 causes an initial retraction of latch member 18intothe housing 17 againstthe force of spring 19, and subsequent emission of latch member 18 undertheforce of spring 19 to the door closed retaining position shown in Figures 1 and 2. In this position the outer race of bearing 21 is in contact with the curved first part 27 of the cam surface 26.An upwardly directed impulsive force of not excessive magnitude applied to the flange 12 causes the bearing 21 to roll along cam surface 27,26 and subsequently, 25 resulting in initial retraction and subsequentemission of the latch member 18andthe opening of door 10. However the door 10 is firmly retained in its closed position by the closure means 13 until such time as the aforementioned upwardly directed impulsive force is applied to flange 12.

By means of the invention, use of a vehicle to which the door 10 is attached can be madewhilstthe door 10 is securely held in its closed position. Howeverthe door 10 can be easily and quickly opened when requiredwithoutthe need to operate pushbuttons, handles, levers or keys. A separate or combined locking mechanism may be provided for sec urityreasons if desired, butwhen such mechanism is unlocked the door 10 can be readily opened or closed, or securely retained in the closed position, solely by means ofthe closure device 13.

Claims (15)

1. A door closure device comprising a body, a latch member mounted in said body so as to be movable relative thereto in a predetermined direction between door retaining and door releasing positions, a latch retaining member having two cam surfaces engageable by said latch member and oppositely in dined relative to said predetermined direction, and roller means mounted on one of said latch member and said retaining member and engaged by the other when said closure device is in said door retaining position.

2. A door closure device according to claim 1 wherein said body is adapted to be mounted on a door and said retaining member is adapted to be mounted on a door surrounding structure.

3. A door closure device according to claim 1 or claim 2 wherein said latch member is resiliently biassed towards said door retaining position.

4. A door closure device according to claim 3 wherein said latch member comprises a rod slidably mounted in said body.

5. A door closure device according to claim 4 wherein a compression spring is mounted around said rod to engage said body and a stop means provided on said rod.

6. A door closure device according to any one of claims 1 to 5 wherein said roller means comprises a bearing.

7. A door closure device according to any one of claims 1 to 6 wherein said roller means is mounted on a free end of said latch member disposed outside said body.

8. A door closure device according to claim 6 or claim 7 wherein a first portion of one of said cam surfaces includes a point of contact of said one cam surface with said roller means when said latch member is in said door retaining position.

9. A door closure device according to claim 8 wherein said first portion is less inclined relativeto said predetermined direction than the remainder of said one cam surface.

10. A door closure device according to claim 9 wherein said first portion is curved.

11. A door closure device according to claim 10 wherein said remainder is rectilinear and substantiallytangential to said first portion.

12. Adoor closure device according to any one of claims 1 to 11 wherein said retaining member is of a plastics material.

13. A door closure device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawing.

14. A roller shutter door comprising at least one door closure device according to any one of claims 1 to13.

15. A roller shutter door according to claim 14 comprising a door closure device attached thereto adjacent each bottom corner of said door.