GB2109086A - Brake bleed nipple seal - Google Patents

Abstract

A brake bleed nipple seal comprises a seal element (1) in the form of a ring for positioning around a bleed nipple between the nut-like part thereof and the wall of the associated brake cylinder, a cap member (6) for fitting over the end of the bleed nipple and a strap (5) attached to the cap (6), the strap (5) being provided with engagement means (4) at its free end which cooperates with the seal element (1) so as to attach the strap (5) and thus the cap (6) to the seal element (1). <IMAGE>

Description

SPECIFICATION Brake bleed nipple seal This invention relates to a brake bleed nipple seal.

In the brake bleeding art, particularly in the use of one man bleeding systems in which, due to a valve provided in the bleeding arrangement, it is not necessary for the brake system to be maintained under pressure while the bleed nipple is being done up, some difficulty has been experienced due to bleed back of air between the screw threads of the brake nipple itself and the brake cyclinder housing. This can occur as a result either of the nipple used, having a screw thread which as the result of manufacturing tolerances, is not as light as is necessary to provide a complete seal and/or due to the possibility that the operator has undone the bleed nipple so far as that insufficient threads remain in contact.

In my prior Patent No. 156880, 1 have described and claimed a brake bleed nipple seal which comprises a resilient bell shaped sealing member adapted to surround the bleed nipple between a nut-like annulus provided for actuation of the nipple and the brake cylinder, the narrow end of the bell being apertured and adapted to seat around the main part of the bleed nipple with its outer surface providing a first sealing surface against the rim of the nut like annulus of the bleed nipple, the wide end of the bell forming a second sealing surface for engaging the body of the brake cylinder, the resilience of the sealing member being such as to retain the two sealing surfaces against the said parts of the bleed nipple and brake cylinder during limited axial movement of the bleed nipple.

While the above seal has been found in practice to be very effective in normal use, nevertheless, in order to fit the seal it is necessary to remove the nipples entirely from the wheel cylinder. While this may not matter a good deal if the seal is supplied as original equipment, it is highly significant if replacement is desired or it is desired to fit them to an existing vehicle. The operation would cause loss of brake fluid and would necessitate complete bleeding of the brakes.

The present invention seeks to provide a brake nipple seal in which some or all of the above disadvantages are reduced or avoided.

According to the invention, there is provided a bleed nipple seal comprising a seal element in the form of a ring for positioning around a bleed nipple between the nut like part and the wall of the brake cylinder, a cap member for fitting over the end of the bleed nipple, a strap attached to the cap and engagement means at the end of the strap, cooperating with the seal element so as to attach the strap to the seal element.

Suitably the seal element may of grommet like form with an outer circumferential groove and the engagement means may comprise a ring which fits into the groove in the seal element. Alternatively the seal element may have an outer rib or projection which fits into an inner groove provided in a ring forming the engagement means.

Preferably the seal element and the engagement means comprise a material of sufficient flexibility or resilience and of such dimensions that they can individually pass over the widest parts of the bleed nipple so that the seal can be assembled without the need for removing the bleed nipple from the brake cylinder. The dimensions may be such that, once assembled the engagement means has a constrictive effect on the seal member whereby there is increased tightness of the seal on the nipple.

The invention will now be described in greater detail, by way of example, with reference to the drawings, in which: Figure 1 is a perspective view of a sealing arrangment in accordance with the invention; Figure 2 is a sectional view through a bleed nipple and its associated cylinder showing the position of the sealing arrangment of Fig. 1 in the closed position of the bleed nipple, and Figure 3 to 6 show various forms of the engagement means and seal illustrating different methods of attachment.

Referring first of all to Fig. 1, the sealing arrangement comprprises a seal 1 of grommetlike construction i.e. a toroid member with an outer circumferential groove 2. This seal 1 is intended to seat between the hexagon portion of a bleed nipple and the wheel brake cylinder as will be described in connection with Fig. 2.

Seated in the groove 3 is an engagement member in the form of a ring 4 carried-by astrap 5.

This strap 5 is connected at its outer end to a cap 6 intended for use as a dust cap 6 for covering the end of the bleed nipple to which the tube of brake bleeding equipment is attached. The cap 6 may be provided in one piece or may have a detachable top or base portion 7 which is of transparent material beneath which can be inserted any desired indication, such as the order in which the various brake culinders should be bled. The parts of the sealing arrangement are suitably produced from rubber a synthetic rubber such as neoprene or a flexible resilient plastics material. For assembly purposes and for anti corrosion reasons, the parts may be made from different materials. For example, the cap and engagement member may be made of flexible plastics material while the seal may be produced from neoprene.

The installation of the sealing arrangement on a bleed nipple will now be described with particular reference to Fig. 2 . In this figure the bleed nipple is given the reference numeral 10 and the brake cylinder is given the reference 11.

As shown in Fig. 2, the arrangement of the nipple and the cylinder is of standard form.

The nipple 10 comprises a main screw threaded body 1 2 which terminates at one end in a conical sealing arrangement 1 3 and at the other end in a straight portion 1 4 bounded by an annular projection 1 5 which has an hexagonal face for actuation by a spanner. The bleed nipple 10 extends in an outward direction and ends in a further annular projection 1 6 which seats and stretches a flexible tube of brake bleeding equipment, (not shown). The nipple 10 has a central bore 1 7 which extends through most of its length and is connected to a radial bore 1 8 which provides for access or brake fluid when the seal portion 1 3 is parted from its seat, here indicated at 19.

As mentioned above, the sealing device of the invention is seated between the annular projection 15 and the outer face 21 of the brake cylinder. Thus the sealing arrangement can be mounted on the bleed nipple by removing the nipple from the cylinder and pushing the seal 1, with its attached engagement ring 4 over the screw threaded body part 1 2.

Once in position the nipple 10 is screwed back into the wheel cylinder.

While such a method of assembly is perfectly good for use as "original equipment", to fit a seal in this way after purchase and/or use of the vehicle will cause loss of brake fluid and the necessity of complete bleeding of the braking system. Thus it is desirable to find a way of placing a seal on the bleed nipple without having to remove the nipple.

With the above described sealing arrangement and with suitable dimensions and material of the various parts, such a fitting of the seal is possible.

Thus in order to install the sealing arrangement, the nipple 10 is undone by a few turns to increase the distance between the projection 1 5 and the face 21 of the wheel cylinder.

The two parts of the sealing arrangement, i.e.

the seal 1 and the ring 4, are separated. The seal is first pushed over the nipple 10 and over the projection 5 so that it lies as shown between the projection 15 and the face 21.

Then the ring 4 which is of larger diameter may be pushed over the projection and seated in the outer groove 2 and the seal 1. The nipple is then again screwed up, compressing the seal 1 and providing a tight seal around the nipple. With'suitable dimensioning of the seal 2, unscrewing the nipple sufficiently for brake bleeding purposes will not lead entirely.

to decompressing the seal 2 which will then remain a tight seal.

With this method of assembly, it is desirable to use a seal of relatively soft rubber, a rubber like material so that it will have sufficient strength to pass over the larger diameter parts of the bleed nipple. On the other hand, the ring 4 being in any event larger than the seal 2 (in fact it may be larger in internal diameter than the projection 1 5) can be readily pushed over the bleed nipple without requiring significant stretching.

If the internal diameter of the ring is smaller than the external diameter of the seal (as measured across the bottom of groove 2).

Then the connection of the ring will compress the seal 1 and provide for improved sealing.

In a still further alternative in the method of assembly, where there is sufficient space between the projection 15 and the face 21 to receive the seal 2, the necessity of undoing the bleed nipple to any extent can be dispensed with the necessary compression of the seal 1 being achieved by means of the ring 4.

This may well mean that the seal is not as strong during a brake bleeding operation, but should prove adequate for low pressure brake bleeding.

While there is no necessity to make the parts of the sealing arrangement of different materials, the life of the arrangement is enhanced if the seal 1 is made of a material which is proof against corrosion by brake fluid, e.g. a rubber material while the ring 4 and cap 6 are made of a material proof against corrosion by oil and water e.g. a suitable plastics material.

Variations of the seal and engagement member are shown in Figs. 3 to 6.

In Fig. 3, the seal 1 comprises a plain toroid seal and the engagement member is provided with a ring 4 which has an internal shape 30 which fits around the outer periphery of the toroid.

Fig. 4 shows the reverse of the construction shown in Fig. 1 in which the seal 1 is provided with a circumferential rib 31 and the ring 4 is enlarged and provided with an internal groove 32 to match the rib 31.

Fig. 5 shows a split ring like formation of the ring 4 which can be used with the grommet type seal 1 in Fig. 1. The split is shown at 33. In this case, once the seal 1 has been pushed over the nipple, the ring 4 is sprung on side ways.

Fig. 6 shows a split ring form for the seal 1 itself. This can be used with the ring 4 of Fig.

5. First the seal 1 is pushed on to the bleed nipple from one side and them the ring 4 is pushed on from the other side. Provided that this attachment from opposite sides is observed the split 34 in the seal 1 will be held closed by the ring 4.

It is to be understood that various modifications may be made to the above described embodiments without departing from the scope of the invention.

For example, while toroidal seals have been shown for the seal 1, other shapes may be used such as cylindrical of square section or of semi troridal section. Other means of securing the engagement member to the seal may be used, such as a plurality of moulded pin and socket connections may be used. Permanent connection may be provided by the use of adhesives.

In the use of the invention, it is additionally envisaged, that while the whole of the arrangement would usually be supplied together, the seal could be used as original equipment and the cap and engagement member could be provided as accessories.

Finally, where the distance between the surface of the brake cylinder and the hexagon of the bleed nipple is very large, one or more additional seals 1 may be used between the seal attached to the strap and the surface of the brake cylinder.

Claims (9)

1. A bleed nipple seal comprising a seal element in the form of a ring for positioning around a bleed nipple between the nut-like part thereof and the wall of the associated brake cylinder, a cap member for fitting over the end of the bleed nipple, a strap attached to the cap, and an engagement means at the end of the strap cooperating with the seal element so as to attach the strap to the seal element.

2. A seal as claimed in claim 1, wherein the seal element is of a grommet like form and the engagement means comprises a ring like member which cooperates therewith.

3. A seal as claimed in claim 2, wherein the seal element has an outer circumferential groove and the engagement means comprises a portion which seats in the groove.

4. A seal as claimed in claim 2, wherein the seal element has an outer rib or projection and the engagement means has an inner groove into which the outer rib or projection fits.

5. A seal as claimed in claim 2, wherein the seal element has an outer circumferential groove and the engagement means comprises a split ring which fits into the groove in the seal element.

6. A seal as claimed in claim 2, wherein the seal element is in section so the form of a split ring and the ring of the engagement means sits around the seal element.

7. A seal as claimed in any one of claims 1 to 3, wherein the seal element and the engagement means comprise a material of sufficient flexibility or resilience and of such dimensions that the seal element and the engagement means can pass individually over the widest parts of the bleed nipple to enable the seal to be assembled without the need for removing the bleed nipple from the brake cylinder.

8. A seal as claimed in any one of claims 1 to 4, wherein the engagement means has a constructive effect on the seal member so that once the seal has been assembled, there is an increased tightness of the seal on the bleed nipple.

9. A bleed nipple seal substantially as described herein with reference to the drawings.