GB2186559A - Lockable fuel filler cap - Google Patents

Abstract

A lockable fuel filler cap with a deadlock mechanism has a barrel 20 which turns within a cylindrical chamber chamber 22. To prevent the cap from being removed from the filler neck with the wrong key, a radial projection 36 is attached to the chamber wall. This projection 36 is spring loaded so that it can be lifted out of the pitch circle of the extended wards 30 of the lock to allow the cap to be relocked. <IMAGE>

Description

SPECIFICATION Fuel filler cap This invention relates to a lockable fuel filler cap for motor vehicles. The invention is particularly concerned with a cap where locking is effected by a high-security deadlock type of lock.

In adeadlockitistheaction of turning the key which causes the lock wards to be retracted or extended. In a fuel filler cap, rotation of the key through a substantial arc (typically about 110 ) is required in orderto release the latching mechanism that secures the filler cap on the neck of a filler pipe.

According to the present invention there is provided a lockable fuel filler cap for a motorvehicle, the cap having a key-freed lock mechanism of a deadlock type in which rotation of a lock barrel in one direction securesthe cap on afiller neck and inthe other direction releases the cap, rotation of the barrel being enabled on insertion of a key, the barrel being mounted in a cylindrical chamber and having radially extendable wards which can be extended from or retracted into the barrel by the key, wherein the internal wall of the cylindrical chamber includes an abutment against which extended wards will abut during rotation of the barrel, to prevent continued rotation, butwhich can be moved radially out ofthe pitch circle ofthe extended wards and against a spring loading, by an applied radial pressure.

The ability to move the abutment radially outwardly meansthatwhen the key isturned inthe direction which causes extension of the wards, the barrel can be turned withoutthe wards being driven against a fixed abutment and thereby resisting the necessary turning movement. Preferably the barrel has two sets of wards which extend at diametrically opposite positionsfrom the valve circumference, and the internal wall ofthe cylindrical chamber includes two diametrically opposite abutments.

The oreach abutment can be formed buy a plate spring attached to the internal chamber wall ata point circumferentially spaced from the position of the abutment and extending around and generally inwardly (along a spiral path) from the internal wall to terminate in an abutment portion bent out ofthe plane of the rest of the spring so as to extend radially towards the centre of the chamber.

The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevation of a cap in accordance within the invention; Figure2 is a section through the cap of Figure 1; Figure 3 is a section through part of the cap on the line B-B from Figure 2; and Figure 4 is a perspective, exploded view of the components shown in Figure 3.

The cap has a cover plate 10, a seal ring 12which will seal againstthe lip atthetop of a filier pipe, and a locking bar 14which engages under an internal lip on thefiller pipe neckto holdthe cap in place.The cap also has a body lfiwhichcontainsthelocking mechanism. There is an aperture (not shown) for insertion of a key, in the cover plate 10.

In use, a key is inserted through the key aperture in the centre of the cover plate 10. The turning ofthe key turns the bar 14 aboutthe axis ofthe cap, so that the bar can move between a free position wherethe bar registers with slots in the filler neck lip and can be lifted away from the filler neck, and a secure position where the bar is retained underthe lip. Anon-circular ring 18 engages in a correspondingly shaped non-circular recess in the filler neck, and prevents rotation of the cover plate 10 relative to the filler neck.

The cross sectional view of Figure 2 shows a lock barrel 20 received within a cylindrical chamber 22. In factthecylindrical chamber22 is made in one piece with the cover plate 10. In use, when a key is inserted in the lock barrel 20 and turned, the cover plate 10 and the cylindrical chamber 22 as well as the seal 12 and the outer plate 24 of the lock barrel are all held stationary by the engagement of the ring 18 in the filler neck. The barrel 20 itself rotates and carries with it in rotation the body 16 and the locking bar 14.The inner end of the barrel 20 is keyed to the body 16 at a region 28. When the the filler cap is secure on afiller pipe neck, a lip of the neck will be retained between the bar 14 and the seal 12.A coil spring 26 urgesthe bar 14towards the seal 12, to provide a positive loading ofthe seal 12 onto the filler neck.

Turning nowto Figure 3, the operation of the lock barrel itself in the cylindrical chamber22 will be described.

The barrel 20 is supported in the casing 22 at its top and bottom ends, so that the barrel can rotate freely withinthe casing. The barrel contains a numberof wards 30 (see Figure 4) and insertion of the correct key into the key slot 32 allows the wards to be extended on turning ofthe key in one direction and retracted on turning of the key in the opposite direction. This is a deadlock mechanism which is well known. There is no spring loading ofthewards.

In Figure4thewards are shown extended, and twill be seen that the wards 30 on one side of the barrel are interleaved with the wards on the other side.

Around the periphery of the chamber 22 are two plate springs 34. These are secured to the internal cylinderwall by means of T-shaped retainers 36 which are formed integ rally with the wall ofthe chamber 22. Each of the springs 34 has atransverse slot 35 which allows it to be dropped down overthe T-formation. The springs 34 then extend along a generally spriral path, and end in a bent-in portion 36 which forms an abutment. Each abutment 36 is formed so that it lies on a radius of the chamber, and in the illustration both of the portions 36 lie on the same diameter.

In the rest position of the springs 34, the tip of each portion 36 will lie on the cylindrical surface ofthe barrel 20. Howeverthe abutments can be pushed backagainstthe internal wall of the chamber 22, by flexing ofthesprings.

In Figure 3, the wards ofthe barrel 20 are shown in three separate positions. The first position, shown in solid lines, is the position taken up when the cap is locked. The second position, shown in dashed lines is the position where the cap is uniocked and can be removed. The third position shown in dotted lines is the position reached when removal is attempted with an incorrect key. From this position it is impossibleto reach the 'cap free' position shown in dashed lines.

Starting from the locked condition with the wards 30 extended in their solid line position shown in Figure 3, the correct key is inserted in the lock and turned in a clockwise direction. The first thing that happens during the first few degrees of rotational movement isthatthe wards are retracted until they lie flush with the surface ofthe barrel 20. In this state, the barrel can be turned until the wards reach the position shown in dashed lines in the Figure. This is the 'cap free' position, and the cap can now be removed.

One characteristic of thins type oflockisthatthekey can only be removed in one rotational position. This is a consequence of the outer plate 24 being fixed, and the shaft of the key being cylindrical.

The keytherefore remains in the lock until the cap is replaced and relocked. On relocking and turning the key anti-clockwise, the first thing that happens is that the wards 30 are extended. This will cause the abutment 36 to be pushed radially outwards. Atthe sametime,the barrel is being rotated and after a few degrees of rotation the abutment36will drop off the extended wards, and the rest of the rotation can be accomplished with the wards extended but without the extended wards coming into contactwith any surface which might impose a resistance to this anti-clockwise turning.

If, alternatively, with the cap in the locked position, the incorrect key is inserted then rotation of the key will still produce rotation of the barrel 20, but in this case the wards 30 will not retract. Barrel rotation will therefore come to an end when the wards take up the position shown in dotted lines, and in this position the cap cannot be removed.

Again, to removethekeyafterthisunsuccessful attempt art unlocking the cap, it is necessaryto return to the initial position to allow the key to be extracted.

The mechanism described allows the cap to be relocked and the barrel to be turned in the cylindrical chamber with the wards extended without the wards coming into contact with a wall surface against which they would tend to be forced by the turning movement ofthe key, thus creating undesirable friction which would severely hinderthe relocking action.

Claims (7)

1. A lockablefuel fillercapfora motorvehicle, having a key-freed lock mechanism of a deadlock type in which rotation of a lock barrel in one direction secures the cap on a filler neck and in the other direction releases the cap, rotation of the barrel being enabled on insertion of a key, the barrel being mounted in a cylindrical chamber and having radially extendable wards which can be extended from or retracted into the barrel bythekey,wherein the internal wall of the cylindrical chamber includes an abutment against which an extended wards will abut during rotation of the barrel, to prevent continued rotation, but which can be moved radially, out of the pitch circle of the extended wards and against a spring loading, by an applied radial pressure.

2. Afuel filler cap as claimed in Claim 1,wherein there are two, diametrically opposite abutments.

3. AfuelfillercapasclaimedinClaim 1 orClaim 2, wherein the or each abutment is formed by a plate spring attached to the internal chamberwall ata pointoircumferentially spaced from the position of the abutment and extending around and generally inwardlyofthe internal walltoterminate in an abutment portion bent out of the plane of the rest of the spring so as to extend radiallytowards the centre ofthe chamber.

4. Afuel filler cap as claimed in Claim 3, wherein the internal chamberwall has an axially extending elongate T-shaped formation and the spring has a slotwhich can fit overtheformation to attachthe spring to the wall .

5. Afuelfillercap asclaimedin anypreceding claim, wherein the abutment is located atthe circumferential position where the centreline ofthe wards lie when the cap is released.

6. Afuel filler cap as claimed in any preceding Claim, wherein the or each abutment is positioned on a diameter of the chamber.

7. A lockable fuel filler cap substantially as herein described with reference to the accompanying drawings.