GB2188971A

GB2188971A - Electromagnetic gate lock

Info

Publication number: GB2188971A
Application number: GB08608913A
Authority: GB
Inventors: Walter Wilson Hugh Clarke
Original assignee: Individual
Current assignee: Individual
Priority date: 1986-04-11
Filing date: 1986-04-11
Publication date: 1987-10-14
Also published as: GB8608913D0; GB2188971B

Abstract

An electromechanical gate lock which does not involve the insertion of a vertically displaceable bolt into a ground hole and wherein there is provided a clothes-peg style clasp having a pair of relatively pivotable clasp members (28, 30) which, in their closed position, are adapted to grasp the upright stem (46) of a mushroom-shaped member (48) which is fixed rigidly to the ground, and a plunger (38) which is spring biassed to engage recesses (42 a,b) and prevent opening movement of the clasp members (28, 30) until retracted by a solenoid (44), whereupon the clasp members (28, 30) can be displaced to an open position in which they can be withdrawn from the stem (46) of the mushroom member to permit the gate to be opened. <IMAGE>

Description

SPECIFICATION Electromechanical gate lock The present invention is concerned with an electromechanical lock for gates and gate-like doors generally.

Particularly for pairs of gates, the only strong way to lock them securely is to the ground. However, this can be difficult when electrical operation is required, since the conventional bolt-receiving hole in the ground tends to fill with dirt and impede the locking action.

A principal object of the present invention is to provide a electromechanical gate lock which does not involve the insertion of a vertically displaceable bolt into a ground hole.

In accordance with the present invention, there is provided a gate lock comprising a clothes-peg style clasp having a pair of relatively pivotable clasp members which, in their closed position, are adapted to grasp the upright stem of a mushroom-shaped member which is fixed rigidly to the ground, and a plunger which is adapted to hold the clasp members in their closed position until retracted by a solenoid, whereupon the clasp members can be displaced to an open position in which they can be withdrawn from the stem of the mushroom member to permit the gate to be opened.

Advantageously, the plunger is displaceable vertically and can drop, preferably with spring assistance, into a recess formed between the clasp member for holding these members in their closed position.

When the gate is in an open position, the clasp members are arranged to be held substantially in their open, i.e. unclasped, position, wherein the recess formed between said clasp members is too small for the plunger to enter. Preferably, this is achieved by means of a substantially flat spring which is attached at one end to a body member of the lock which houses the solenoid and whose other, depending end is arranged to be received in a second recess formed between the clasp members, the spring being biassed to enter a smaller portion of the latter recess as the lock is withdrawn from the mushroom stem such that the clasp members are prevented from returning to a position in which the plunger can enter the first-mentioned recess.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a partially sectioned, side elevation of one embodiment of a lock in accordance with the present invention; Figure 2 is a front view of the lock of Fig.

1; Figure 3 is a diagrammatic plan view of the lock of Figs. 1 and 2; Figure 4 is a plan view of a clasp portion of the lock; Figure 5a is an end view of the clasp portion of Fig. 4 in a direction A; and Figures 5b and 5c are diagrammatic sections on lines B and C in Fig. 4, respectively.

The illustrated lock is mounted in or at the bottom edge of a hinged door or gate 10, in the corner opposite to the hinged edge of the door. It is therefore positioned at approximately the same location as one would mount a conventional vertically displaceable bolt which is intended to be introduced into a ground aperture for securing the gate in a required position.

The lock comprises a metal body 12 whose base contains a pair of vertical blind bores 14, 16, each of which pivotally supports a respective stub shaft 18 by means of a respective pair of axially spaced sleeve bearings 20, 22.

The inner ends of the stub shafts 18 are retained within the blind bores 14, 16 by means of a cross bar 24 which passes through the body 12 and also through respective transverse through-bores 26 in the shafts 18.

The bores 26 are of somewhat greater diameter than the bar 24 so that the shafts 18 are capable of limited rotational movement within the bearings 20, 22. The end of the stub shafts 18 projecting downwardly out of body 12 are welded to respective ones of a pair of clothes-peg style clasp members 28, 30 (see Fig. 4 in particular), which are thereby also capable of limited rotation with the stub shafts 18. The clasp members 28, 30 are normally biassed to their closed position (as shown in Fig. 4) by means of a helical coil spring 32 whose two ends are received in respective blind bores 34, 36 in the clasps 28, 30.

The body 12 also provides a housing for a solenoid operated plunger 38 which is normally biassed downwardly by means of a coil spring 40 so that its lower end projects out of the body 12 and into the gap between a pair of recesses 42a, 42b in the clasp members 28, 30, but which can be raised clear of these recesses 42a, 42b upon energisation of the solenoid 44. In this example, the solenoid 44 comprises three individual coils. However, the use of three coils is of no significance and other numbers of coils could equally well be used.

The body 12 is constructed in two parts for ease of manufacture and choice of materials.

The main part is made of steel to give strength to the mounting of the clothes peg clasp. Thus, it can be welded to a gate or fixed using lapped holes. The other part is made of aluminium and carries the solenoid 44. Alternative materials can of course be used.

The clasp members 28, 30 of the clothespeg style clasp are adapted and dimensioned to grip the stem 46 of a permanent ground fixture in the form of a mushroom shaped member 48. The button portion 50 of the member 48 prevents the door/gate 10 being lifted off its retainer. With the clasp members engaged around the stem 46 of the mushroom, the clasp is normally prevented from opening as a result of the plunger dropping down and engaging between the recesses 42a, 42b. When the door/gate is to be opened, the plunger is withdrawn by the solenoid to enable the two parts 28, 30 of the clasp to be pivoted against the action of the separator spring 32.

A sprung leaf spring (strap) 52 is attached at one end to the body 12 by screws 54 and its other end extends downwardly into an aperture 56 formed by a further pair of opposed recesses in the clasp members 28, 30.

The spring 52 is received normally in a wider portion 58 of the aperture 56. With the clasp members 28, 30 in their closed position shown in Fig. 4, the spring 52 is too wide to be received in a narrower portion 60 of the aperture 56. However, when the clasp members have been displaced, against the bias of the spring 32, into their open position, the narrow portion 60 of the aperture 56 is expanded to a width sufficient to accommodate the spring 52. The spring 52 is biassed by its own inherent resilience to enter the narrow portion 60 of the aperture 56 in this condition, thereby preventing the clasp members 28, 30 from closing again. It will be noted that in this open position of the clasp members 28, 30, the two recesses 42a, 42b are brought together sufficiently for the gap therebetween to be too small to recieve the plunger 38.The plunger is thereby prevented from engaging in this condition.

In use, as the door/gate 10 is withdrawn from the mushroom 48, the leaf spring 52 is able to enter the narrower portion 60 of the aperture 56 so that it acts to wedge partly open the front part of the clasp and correspondingly close the rear part. This therefore prevents the solenoid plunger 38 from dropping while the door/gate is open. However, on reclosing the door/gate, the flat spring 52 is pushed back by the button 50 of the mushroom 48 into the wider part 58 of the aperture 56 so that the clasp can then close fully around the stem 46 and the plunger 38 can drop into the gap between the recesses 42a, 42b, thereby preventing subsequent opening of the clasp from the stem until such time as the solenoid is energised.

A thin plate 62 is affixed to the base of one of the clasp members 28, 30 and is shaped and dimensioned to prevent anyone pushing up the solenoid plunger 38 by hand.

The mushroom 48 is attached to or is integral with a base plate 64 which bolts to the ground or roadway.

Where a pair of doors/gates is used, each such door/gate would preferably have its own lock. The clasps of such two locks can, however, operate with a single mushroom 48 if the clasps of the two locks are disposed at different heights so that they engage the stem 46 of the mushroom one above the other.

Further, a single lock can be used on one gate with a rebate plate and a special fixed bracket mounted on the other gate so as to engage the first edge of the mushroom shank just below the clasp from the lock on said one gate. Said other gate can thus not be moved outwards as the bracket interferes with the mushroom, or inwards because of the rebate plate once said one gate has been locked.

Fig. 1 includes an optional microswitch 66 which can be used to provide electrical signals indicative of the position of the plunger 38, i.e. corresponding to the "lock open" and "lock closed" conditions, respectively.

Claims

1. A gate lock comprising a clothes-peg style clasp having a pair of relatively pivotable clasp members which, in their closed position, are adapted to grasp the upright stem of a mushroom-shaped member which is fixed rigidly to the ground, and a plunger which is adapted to hold the clasp members in their closed position until retracted by a solenoid, whereupon the clasp members can be displaced to an open position in which they can be withdrawn from the stem of the mushroom member to permit the gate to be opened.

2. A gate lock as claimed in claim 1, wherein the plunger is displaceable vertically and can drop into a recess formed between the clasp member for holding these members in their closed position.

3. A gate lock as claimed in claim 2, wherein the dropping of the plunger into said recess is spring-assisted.

4. A gate lock as claimed in claims 1, 2 or 3, wherein, when the gate is in an open position, the clasp members are arranged to be held substantially in their open, i.e. unclasped, position, wherein the recess formed between said clasp members is too small for the plunger to enter.

5. A gate lock as claimed in claim 4, including a substantially flat spring which is attached at one end to a body member of the lock which houses the solenoid and whose other, depending end is arranged to be received in a second recess formed between the clasp members, the spring being biassed to enter a smaller portion of the latter recess as the lock is withdrawn from the mushroom stem such that the clasp members are prevented from returning to a position in which the plunger can enter the first-mentioned recess.

6. A gate lock as claimed in any of claims 1 to 5 wherein there is included a microswitch which is adapted to be activated by the plunger to provide an electrical signal inductive of the operational position of the plunger.

7. A gate lock substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.