GB2049017A - An operating mechanism for door latch - Google Patents

Abstract

An operating mechanism (2) for door latch apparatus, which mechanism comprises latch operating means (4, 6), a spring biasing arrangement (22, 32, 36) for the latch operating means, and a back plate (40), the latch operating means being movable with respect to the back plate for operating a latch and being spring biased by the spring biasing arrangement to a rest position, the spring biasing arrangement being housed on the side of the back plate that is remote from a door when the operating mechanism is in use and is installed on a door. <IMAGE>

Description

SPECIFICATION An operating mechanism for door latch apparatus This invention relates to an operating mechanism for door latch apparatus.

More specifically, this invention provides an operating mechanism for door latch apparatus, which mechanism comprises latch operatingmeans, a spring biasing arrangement for the latch operating means, and a back plate, the latch operating means being movable with respect to the back plate for operating a latch and being spring biased by the spring biasing arrangement to a rest position, and the spring biasing arrangement being housed on the side of the back plate that is remote frqm a door when the operating mechanism is in use and is installed on a door.

By housing the spring biasing arrangement on the side of the back plate that is remote from the door, the operating mechanism can be easily installed on the door and rebating of the door to receive the spring biasing arrangement is not necessary. As will be explained in more detail herein below, the positioning of the spring biasing arrangement lends itself to enabling the latch operating means to be so mounted that wearing of the various parts of the operating mechanism does not result in the latch operating means feeling loose as it is being used.

The latch operating means may include a rotatable lever handle or a rotatable knob handle.

In this case, the spring biasing arrangement may be housed in a hollow cylindrical member which extends outwardly from the back plate and which receives a part of the rotatable lever handle or the rotatable knob handle. The spring biasing arrangement may also be housed in a sleeve part of the rotatable lever'handle or the rotatable knob handle. The part of the rotatable lever handle or the rotatable knob handle inside the hollow cylindrical member can rotate within the hollow member and it is supported by the hollow member for substantially its entire length which gives a precise feel to the rotatable lever handle or the rotatable knob handle even after wear of the operating mechanism may have taken place.

The latch operating means may also comprise a push-button.

When the latch operating means comprises a push-button, the spring biasing arrangement is preferably housed in a hollow cylindrical member extending from the back plate.

When a push-button is employed, the latch operating means preferably also includes a rotatable plug having a cam groove which cooperates with a fixed pin, the push-button being movable longitudinally to cause rotational movement of the rotatable plug.

When the latch operating means comprises the rotatable lever handle or the rotatable knob handle, the spring biasing arrangement will usually include a return spring.

When the latch operating means comprises the rotatable lever handle or the rotatable knob handle, the operating mechanism will usually include stop means for limiting the clockwise and the anti-clockwise rotation of the rotatable lever handle and the rotatable knob handle.

The stop means may comprise a pair of stop washers having abutments for effecting the limitation of the clockwise and the anti-clockwise rotation of the rotatable lever handle or the rotatable knob handle. The stop means may also comprise a pin and groove device, the groove being provided in the rotatable lever handle or the rotatable knob handle. The stop means may further comprise an abutment member and a part circular cylinder, the abutment member being provided on the rotatable lever handle or the rotatable knob handle.

When the latch operating means comprises a push-button, the spring biasing arrangement preferably comprises a coil spring.

Advantageously, one end of the coil spring abuts against the push-button and the other end of the coil spring abuts against an abutment washer.

The latch operating means may include a spindle but, if desired, the operating mechanism of the invention may be manufactured and sold without the spindle. Usually, the spindle will be of square cross section.

The operating mechanism may be sold with or without the door latch apparatus. The door latch apparatus may or may not be associated with a key locking mechanism. The precise construction and operation of the door latch apparatus and the key locking mechanism may be the same as in the known and presently available door latch apparatus and key operated locking mechanisms.

Embodiments of the invention will now be described solely by way of example and with reference to the accompanying drawings in which: Figure 1 is an exploded view of a first operating mechanism for door latch apparatus; Figure 2 is an amplified section through the operating mechanism shown in Figure 1; Figure 3 is an exploded view of a second operating mechanism for door latch apparatus; Figure 4 is an enlarged section through the operating mechanism shown in Figure 3; Figure 5 is a perspective view showing part of a third operating mechanism for door latch apparatus; Figure 6 is an exploded view of a fourth operating mechanism for door latch apparatus; Figure 7 is an enlarged section through part of the operating mechanism shown in Figure 6; Figure 8 is a section through the operating mechanism on the line 3-3 illustrated in Figure 7;; Figure 9 is an exploded view of a fifth operating mechanism for door latch apparatus; Figure 10 is a section through the operating mechanism shown in Figure 9; and Figure 11 is a cross section through the operating mechanism as shown in Figure 10.

Refering to Figures 1 and 2, there is shown a first operating mechanism 2 for door latch apparatus. The operating mechanism 2 comprises latch operating means in the form of a rotatable lever handle 4 and a spindle 6 which is of square cross section as shown. The lever handle'4 comprises a first part 8 which fits over a reduced diameter portion 10 of a second part 1 2 of the lever handle 4. The two parts 8, 12 are secured together by a screw (not shown) passing through an aperture 14 in the first part 8 and into a screw threaded recess (not shown) in the second part 12. The second part 12 is provided with another reduced diameter portion 1 6 which is provided with a bore 18 of square cross section and which is for receiving the spindle 6. The spindle 6 is fixed in position- in the bore 18 by means of a screw 20.

Although the first part 8 of the lever handle 4 is shown as being in the form of a hollow cylinder, the second part 12 can be substantially entirely solid or part hollow as may be desired.

The operating mechanism 2 further comprises a spring biasing arrangement for the latch operating means. This spring biasing arrangement comprises a return spring 22. The return spring 22 is operatively associated with stop means in the form of a pair of stop washers 24, 26. Each stop washer 24, 26 is provided with a right-angled abutment member 28, 30 respectively for limiting the clockwise and anti-clockwise rotation of the lever handle 4 and therefore the spindle 6. The stop washer 24 is provided with an aperture 32 for receiving the end 34 of the return spring 22.

The stop washer 26 is provided with an aperture 36 for receiving the end 38 of the return spring 22.

The operating mechanism 2 further comprises a back plate 40. The back plate 40 is provided with four apertures 42 for fixing the back plate 40 to the face of a door (not shown). The back plate 40 is also provided with a slot 44 for receiving a key, which is not shown and which is for operating a key-operated locking mechanism which is also not shown. The back plate 40 is further provided with an aperture 46 for receiving a threaded boss portion 48 of a fixing member 50.

The fixing member 50 has a flange 52 which fits in a countersunk portion 54 of the back plate 40 so that it lies flush with the rear surface of the back plate 40. A hollow cylindrical member 56 screws over the threaded boss portion 48 and tightly draws the flange 52 into the recessed portion 54 of the plate 40. The member 56 thus projects from the front face 58 of the back plate 40 and is securely located in position.

The portion 16 slides into the member 56 with the stop washer 24 abutting the end face 60 of the portion 16 and the end 34 of the return spring 22 that passes through the aperture 32 in the stop washer 24 further passing into a recess 62 in the end face 60. The end 38 of the return spring 22 that passes through the aperture 36 in the stop washer 26 locates in a recess 64 in the end face 66 of the threaded boss portion 48. The shoulder 68 formed where the reduced diameter portion 16 extends from the main body of the second part 12 abuts against the end face 70 of the member 56.

An aperture 72 in the member 56 allows access to be had to the screw 20.

In its normal rest position, the operating mechanism 2 will be such that the return spring 22 biases the lever handle 4 to a normal rest position. In this position, the face 74 of the abutment member 28 will engage the face 76 of the abutment member 30. As the lever handle 4 is turned, these two abutting faces 74, 76 will come out of engagement and the lever handle 4 can be turned until the face 78 on the abutment member 30 engages the face 80 on the abutment member 28. Rotation of the lever handle 4 causes the spindle 6 to also rotate, the spindle 6 passing through central apertures 82, 84 in the stop washers 24, 26. The spindle 6 at its end portion remote from the lever handle 4 can operate door latch apparatus which is not shown and which can be of a standard known design.Rotation of the lever handle 4 will increase the tension in the return spring 22 so that when the lever handle 4 is released, the return spring 22 will tend to unwind to its normal position and the lever handle 4 will be returned to its normal rest position.

During the clockwise and anti-clockwise rotation of the lever handle 4, the portion 16 will be rotating in the member 56. It will be seen that the entire length of the portion 1 6 will be in the member 56 and this large bearing surface formed between the portion 1 6 and the member 56 gives a firm feel to the lever handle 4, even in the event that various parts of the operating mechanism 2 begin to wear, and the lever handle 4 is thus prevented from feeling unduly loose. It will be appreciated from Figures 1 and 2 that the spring biasing arrangement constituted by the return spring 22 and the apertures 32, 36 in the stop washers 24, 26 is housed on the side of the back plate 40 that is remote from a door when the operating mechanism 2 is in use and is installed on a door.In the illustrated embodiment, the spring biasing arrangement is in fact housed in the member 56. The rear side of the back plate 40 is thus substantially flat and it can easily be fixed to the surface of a door without the need for rebating part of the door to receive the various parts of the operating mechanism 2.

Referring to Figures 3 and 4, there is shown a second form of operating mechanism 2. Many of the parts of the operating mechanism 2 illustrated in Figures 3 and 4 are the same as in Figures 1 and 2. These parts have therefore been given the same reference numeral and their description and operation will not again be given. A feature of some of the parts is that they can be used in either the embodiment illustrated in Figures 1 and 2 or the embodiment illustrated in Figures 3 and 4, although some portions of the parts may not be needed in one or other of the embodiments. For example, the fixing member 50 can be used in both illustrated embodiments of the invention although the recess 64 is only required in the embodiment of the invention illustrated in Figures 1 and 2.

In Figures 3 and 4, the main difference is that the lever handle 4 has been replaced by a pushbutton 86 and this requires a different spring biasing arrangement than that illustrated in Figures 1 and 2. The push-button 86 has a cylindrical portion 88 which is hollow so that it has a bore 90. The cylindrical portion 88 is located in the member 56 over the top of a slug 92 which is rotatably mounted in the member 56 and which is provided with a cam groove 94. The slug 92 is further provided with a bore 96 which is of square shape in cross section and which is for receiving the spindle 6. A pin 98 extends into the bore 90 of the cylindrical portion 88 and it engages in the cam groove 94.

The push-button 86 is provided with a pair of flat sides 100, 102 and these flat sides fit into a correspondingly flat shaped recess 104 in the second part 1 2 of the handle 4. The handle 4 enables a person wishing to open the door to obtain purchase whilst the push-button 86 is pushed. The face 106 of the push-button 86 extends through an aperture 108 in the second part 12 of the handle 4. It will be noticed from Figure 1 that the handle part 12 may be provided if desired with this aperture 108 so that minimal alteration is needed to the parts 1 2 for the embodiments of Figures 1 and 2 and 3 and 4.

In Figures 3 and 4, a coil return spring 110 is employed and is provided inside the push-button 86. One end of the coil spring 110 abuts against the inside of the face 106 and the other end of the coil spring 110 abuts against an abutment washer 112. The face of the abutment washer 112 remote from the coil spring 110 receives the end face 114 of the spindle 6, thus ensuring that the spindle 6 does not force its way through the centre of the coil spring 110. In the use of the operating mechanism 2 illustrated in Figures 3 and 4, inward pressure towards the back plate 40 of the push-button 86 causes the push-button 86 to move towards the back plate 40 in an axial manner and without rotation. The pin 98 is forced along the cam groove 94 and in doing so the pin 98 pauses slug 92 to rotate.Since the spindle 6 is fixed in the bore 96 of the slug 92, the spindle 6 is also caused to be rotated and thus the latch of the door which is opratively associated with the spindle 6 is caused to be opened. When the pushbutton 86 is released, the coil spring 110 forces it back to its rest position in'which it will be in the aperture 108. The pin 98 will move in the opposite direction in the cam groove 94 and it will thus cause the slug 92 to rotate in the opposite direction. The spindle 6 and the latch will thus also move in the opposite direction. The handle 4 can thus be used merely for pulling the door and it will not be rotatable. The handle 4 can be secured to the member 56 by a screw 116 which passes through an aperture 118 in the handle part 12 and into the member 56 as illustrated most clearly in Figure 4.

Referring now to Figure 5, there is illustrated a different type of lever handle arrangement 11 8 in which a lever handle 120, which may be of circular or half-circular cross section, fits into a half circular recess 122 in the end face 124 of a rotatable knob type handle 1 26. A screw which may be housed inside the knob handle 126 holds the lever handle 120 in position.

Referring to Figures 6 to 8, there is shown an operating mechanism 2. Many of the parts of the operating mechanism 2 are the same as illustrated in Figures 1 and 2. These parts have therefore been given the same reference numeral and their description and operation will not again be given.

In Figures 6 to 8, the stop washers 24, 26 of Figures 1 and 2 have been omitted and the spring 22 has one end 34 located in the recess 62 in the end face 60 of the lever handle 4 and its other end located in the recess 64 in the end face 66 of the fixing member 50.

The fixing member 50 is secured to the back plate 40 by a pair of rivets (not shown) passing into recesses 128, 130 in the fixing member 50.

The member 56 is a pressure fit over the fixing member 50 and a screw 132 passes through the aperture 72, which is screw threaded to receive the screw 132.

The reduced diameter portion 1 6 of the lever handle 4 is provided with a groove 134. The groove 1 34 receives the concial end 136 of the screw 132. The groove 134 is chosen to be of such a length that when the lever handle 4 is rotated through approximately 450, the groove 1 34 will have moved with respect to the screw 1 32 such that the screw 132 will effectively have traversed the entire length of the groove 1 34.

Thus, as the lever handle 4 is manually rotated clockwise to operate the door latch apparatus, the end 1 36 of the screw 1 32 will be caused to abut against one end of the groove 1 34 and this will prevent further clockwise rotation of lever handle 4. When the lever handle 4 is released, the spring 22 will cause the lever handle 4 to rotate anticlockwise and this ahti-clockwise movement will be stopped by the end 136 of the screw 132 abutting against the other end of the groove 1 34.

The screw 1 32 thus acts with the groove 134 to limit the amount of rotational movement of the lever handle 4. The screw 132 also acts to retain the reduced diameter portion 1 6 of the lever handle 4 in the member 56. before the screw 132 is screwed into the groove 134, the lever handle 4 has to be rotated to bring the groove 1 34 into position. The lever handle 4 will be rotated when the spring ends 34, 38 are in their respective recesses, 62, 64 so that the spring 22 will be brought under tension. It is this tension in the spring 22 which is effective to rotate the lever handle 4 anticlockwise as mentioned above.

In order to facilitate smooth rotation of the reduced diameter portion 1 6 in the member 56, the reduced diameter portion 1 6 is advantageously provided with a plastics sleeve which may be shrunk into position and which may be made, for example, of nylon.

The second part 12 of the lever handle 4 is provided with a closed bore 1 38 for receiving one end of the lever handle 4. The lever handle 4 is retained in position in the bore 138 by a screw 140 which extends through an aperture 142 in the end wall of the second part 12 defining the end of the bore 1 8. Access to the screw 140 is obtained through the bore 1 8.

The end of the first part 8 of the lever handle 4 remote from the second part 12 of the lever handle 4 is bent through 450 as shown.

Referring now to Figures 9 to 11, many of the parts of the operating mechanism 2 are the same as illustrated in Figures 1 and 2. These parts have therefore been'given the same reference numeral and their description and operation will not again be given.

In Figures 9 to 11, the end 34 of the return spring 22 fits in a key way 1 50 in a steel washer 1 52. The washer 1 52 has a central aperture 1 54 which is shaped as shown to fit over the similarly shaped end portion 156 of the reduced diameter portion 1 6. The washer 1 52 thus cannot rotate on the end portion 1 56. The washer 1 52 is held in position by a circlip 1 58 which locates in a groove 160 in the end portion 156.

The washer 1 52 is effective top hold a nylon cylinder 1 62 and a nylon washer 1 64 on the reduced diameter portion 1 6, the washer 16six abutting against the shoulder 68. The cylinder 1 62 is only part circular as shown and it terminates in free edges 1 66, 1 68. The washer 1 64 has a key way 1 70 which fits over an elongate abutment member 1 72 attached to the reduced diameter portion 1 6. The abutment member 172 co-operates with the key way 170 to prevent the washer 1 64 from rotating with respect to the reduced diameter portion 1 6.

The cylinder 162 is provided with a screw threaded aperture 1 74. The screw 132 passes through the aperture 72 in the member 56 and screws into the aperture 1 74 in the cylinder 1 62.

The cylinder 1 62 is thus retained in position in the member 56 and the abutment member 172 will be located between the edges 1 66, 168. As the lever handle 4 is turned, the rotation of the lever handle 4 will be arrested by the abutment member 172 engaging either the edge 1 66 or the edge 168. When the lever handle 4 is released, the return spring 22 will cause the lever handle 4 to return to its position of rest in which the abutment member 172 will engage the other edge 166, 168 of the cylinder 1 62. The distance apart of the edges 1 66, 1 68 can advantageously be such that the lever handle 4 can be rotated through 570.

In Figures 9 to 11, the member 56 is provided with a pair of apertures 1 76 which enable the member 56 to be screwed to the back plate 40 via apertures 1 78 in the back plate 40.

The operating mechanism 2 illustrated in the drawings may be made from various metals and various plastics materials. Examples of metals that may be employed are aluminium and brass and examples of plastics materials that they may be employed are Nylon and ABS.

It is to be appreciated that the embodiments of the invention described above with reference to the drawings have been given by way of example only and that modifications may be effected. Thus, for example, different types of latch operating means and different types of spring biasing arrangements to those illustrated in the drawings may be employed. A smaller type of back plate 40 could be employed without the slot 44 for a key.

Other types of handles may be employed. In Figures 1 and 2, the abutment members 28, 30 need not be right angled and the spring 22 may be secured in position without the stop washers 24, 26. In Figures 6 to 8, the lever handle 4 can be rotated through more or less than 450 by varying the size of the groove 134. Also in Figures 6 to 8, the screw 132 could be replaced by a pivot which is secured in position, or the screw 1 32 could locate in a wedge on the inside of the member 56vie The use of the wedge (not shown) obviates the need for screw threads in the wall of the member 56 and the wedge acts in the groove 134 as a stop member to limit the clockwise and the anticlockwise rotation of the lever handle 8.

Claims (14)

1. An operating mechanism for door latch apparatus, which mechanism comprises latch operating means, a spring biasing arrangement for the latch operating means, and a back plate, the latch operating means being movable with respect to the back plate for operating a latch and being spring biased by the spring biasing arrangement to a rest position, and the spring biasing arrangement being housed on the side of the back plate that is remote from a door when the operating mechanism is in use and is installed on a door.

2. An operating mechanism according to claim 1 in which the latch operating means includes a rotatable lever handle or a rotatable knob handle.

3. An operating mechanism according to claim 2 in which the spring biasing arrangement is housed in a hollow cylindrical member which extends outwardly from the back plate and which receives a part of the rotatable lever handle or the rotatable knob handle.

4. An operating mechanism according fo claim 1 in which the latch operating mechanism comprises a push button.

5. An operating mechanism according to claim 4 in which the spring biasing arrangement is housed in a hollow cylindrical member extending from the back plate.

6. An operating mechanism according to claim 4 or claim 5 in which the latch operating means includes a rotatable plug having a cam groove which co-operates with a fixed pin, the push button being movable longitudinally to cause rotational movement of the rotatable plug.

7. An operating mechanism according to claim 2 or claim 3 in which the spring biasing arrangement includes a return spring.

8. An operating mechanism according to any one of claims 2, 3 and 7 including stop means for limiting the clockwise and anti-clockwise rotation of the rotatable lever handle and the rotatable knob handle.

9. An operating mechanism according to claim 8 in which the stop means comprises a pair of stop washers having abutments for effecting the limitation of the clockwise and the anti-clockwise rotation of the rotatable lever handle or the rotatable knob handle.

10. An operating mechanism according to claim 8 in which the stop means comprises a pin and a groove device, the groove being provided in the rotatable lever handle or the rotatabe stop handle.

11. An operating mechanism according to claim 8 in which the stop means comprises an abutment member and a part circular cylinder, the abutment member being provided on the rotatable lever handle or the rotatable knob handle.

1 2. An operating mechanism according to any one of claims 4 to 6 in which the spring biasing arrangement comprises a coil spring.

1 3. An operating mechanism according to claim 12 in which one end of the coil spring abuts against the push-button and the other end of the coil spring abuts against an abutment member.

14. An operating mechanism according to any one of the preceding claims in which the latch operating means includes a spindle.

1 5. An operating mechanism substantailly as herein described with reference to the accompanying drawings.