GB2342709A - Shear valve - Google Patents

Abstract

A shear valve (13) for a petrol pump delivery system comprises a valve body formed from two separable parts (21,22) connected by a frangible tie bolt (27). The separable parts each house valve members (25,26) at least one of which is held off its associated valve seat solely by the tie bolt. The tie bolt (27) has a necked down portion (36), preferably aligned with a plane of contact between parts (21,22), which allows the bolt to shear upon sustaining a lateral impact. This allows the valve or valves to close under bias to prevent the escape of any fuel vapour. The tie bolt may carry one or both the valve members. One of the valve members may be a check valve see figure 2. A fuel delivery installation comprising a fuel dispensing pump (6) connected to a fuel storage tank (1) via a fuel supply line and a vapour recovery line (7) including such a shear valve is also disclosed.

Description

ULVE This invention relates to shear valves intended for use with petrol pump delivery systems.

It is becoming increasingly a requirement that dispensing of fuel to motor vehicles should be accompanied by recovery of vapour displaced during the filling operation. As a result, the petrol pump in addition to having a fuel delivery line from an underground fuel tank, will also include a vapour recovery line which is plumbed into the vapour vent line of the underground storage tank itself.

There is also likely to be a legal requirement shortly in the United Kingdom, that fuel delivery pumps in filling stations should be provided with connections to the liquid fuel lines and vapour recovery lines which if damaged by, e. g. an impact from a motor vehicle, will break in such a way as to shut off the fuel and vapour connections so as to minimise leakage of fuel in such an incident onto the forecourt of the filling station.

The present invention is therefore directed to the provision of arrangements for overcoming the above problems.

According to one aspect of the present invention there is provided a valve for use in a fuel delivery system, which comprises a valve body formed from two separable parts, a valve operating member in each part, at least one of which is normally in an open position, the open valve operating member being held in its open position by a readily frangible elongate tie member, whereby on sustaining a lateral impact to the valve, the tie member is severed, thereby causing said open valve operating member to close.

In one form of the invention, the valve is intended for controlling the vapour return line and the tie member in this case connects the normally open valve member in one valve body part, to the other valve body part. On severing the connection between the two valve body parts, the tie member will be broken and the open valve member will close. This will prevent vapour escaping from the pump and causing a hazard.

In a preferred embodiment, the tie member extends between valve members in each valve body part and holds both valves in their open positions. In the event of the shear valve being broken, e. g. of a vehicle accidentally striking the pump housing, the tie member will break and allow both valves to close simultaneously. This will prevent vapour escaping from the pump and also from the vapour recovery line to the storage tank. The valves of the present invention may also be used in the fuel line to the pump and, in the event of damage to the pump, will prevent any fuel which was in the pump at the time when the damage occurred from leaking onto the forecourt.

In general, in order to avoid any risk of the valve body shielding or protecting the frangible tie member in a lateral impact, the valve body parts are arranged so that contact is confined substantially to an area which lies on, or close to, a plane which passes through an anticipated shear line of the bolt.

Further features of the present invention will become apparent from the accompanying drawings, in which: Figure 1 illustrates the conventional connection between a petrol delivery pump and an underground fuel storage tank, Figure 2 is a section through a valve in accordance with the invention, designed for controlling the vapour recovery line from the delivery pump, Figure 3 is a section through a valve in accordance with the invention, intended for use in controlling accidental spillage of fuel from the fuel delivery line, Figure 4 is a view, partly in section, which shows a modification of the valve shown in Figure 2, Figure 5 is a part sectional view of a further embodiment of a shear valve, primarily designed for controlling the vapour recovery line and preventing escape of vapour in the event of an accident to the delivery pump, Figure 6A is a side elevation showing the way in which the shear valve is mounted in the fuel delivery pump housing, Figure 6B is a plan view of the installation shown in Figure 6A, and Figure 7 shows a tool for facilitating the proper installation of a shear valve in accordance with the invention.

Referring to the drawings, and first to Figure 1, the storage tank 1 is connected to the petrol pump 6 via a suction line 2 and also to a vapour vent line 3, which may be connected to a single vent line 4, or to a manifolded vent line 5, connected also to other fuel storage tanks. The delivery pump 6 also incorporates a vapour recovery line 7, which is connected to the main vapour vent line 3 or direct to the top of the storage tank.

At the point of delivering the fuel, a delivery hose and nozzle may be used which can be sealingly engaged with the fuel tank and deliver fuel through an inner coaxial tube while recovering vapour through an outer, annular tube. One typical system of this kind is available from Dover International BV of Zwanenburg, the Netherlands, and is sold as the OPW-11-VF vapour recovery nozzle.

In other systems, a vapour recovery line is contained within the fuel delivery nozzle and extracts vapour back to the vapour recovery line 7.

The present invention provides a solution to the problem of retaining fuel and vapour within the fuel dispensing pump 6 in the event of an accident which would cause fuel in the suction line 2 and/or the vapour line 7 to be fracture. Valve assemblies in accordance with the invention preferably also automatically shut off the vapour and fuel lines to the storage tank in the case where the dispensing pump is damaged in an accident.

Referring to Figure 3, this shows a section through a valve 13 located beneath the delivery pump 6 to control escape of fuel in the event of damage to the dispensing pump structure. The valve shown in Figure 3 comprises a valve body in two connected tubular parts 21 and 22. Parts 21 and 22 are separate parts and are held together solely by a frangible shear bolt 27. When fitted together, tubular parts 21 and 22 provide a conduit for fuel to flow through the valve in the direction of the arrow. Parts 21 and 22 are sealed together by a face 23 on part 22 which seals against an'0'ring 24 carried in a groove in the other part. A pair of valve operating members 25 and 26 are mounted within the valve body and are connected by the frangible shear bolt 27, having its opposite ends screwed into valve members 25 and 26. Shear bolt 27 slides within tubular portions 28 and 29 of the valve body members 21 and 22. Each of valve operating members 25 and 26 are provided with springs 30 and 31 which may or may not be of the same spring force. Springs 30 and 31 are provided to bias the valve members 25 and 26 into contact with their respective valve seats 32 and 33, but are prevented from closing onto their seats by the tie bolt 27.

In use, it is intended that the valve shown in Figure 3 would be connected so that the end 34 is connected to the suction line 2. However, since the valve is essentially symmetrical about the connection between the two valve body parts, it could be connected the other way round.

In the event of serious impact damage to the petrol pump, the shear bolt 27 will fracture. Because the shear bolt 27 has a necked-down portion 36 in the region of the connection between the two valve body parts, the bolt will fracture at this point.

Once the shear bolt fractures, there is nothing to hold the two valve body parts together and they will separate at the face 23. At the same time, the springs 30 and 31 will close the valve members 25 and 26 onto their respective seats. The shear bolt should preferably be manufactured from a brittle material such as cast-iron.

Preferably, however, the shear bolt and the tubular parts into which it fits are made from non-sparking materials such as brass. A brittle grade of brass is preferably selected for the shear bolt. The shear bolt may be pre-stressed and designed to fracture in the event of the valve sustaining a lateral impact of predetermined amount likely to cause damage to the pump. As can be seen from Figure 3, the parts 21 and 22 incorporate means for aligning or centering one part with respect to the other comprising a tapered projection 38 on one part which mates with a corresponding recess 39 on the other part. Other than these tapering portions, there is no engagement between the tubular parts and, apart from the frangible bolt, the shear valve provides no resistance to a lateral impact force or turning movement.

It is also of some importance to note that the parts of the valve body do not interlock or interengage in a way which could restrict the desired parting of the two valve parts under a lateral impact. As can be seen, the sole contact area between the two separable parts of the valve body lie at or close to the plane of the shear line A-B, which passes through the weakened notch 36 of the bolt 27.

Consequently, when the valve sustains damage causing breakage of the frangible bolt, no further fuel can be delivered from the line 2 and any fuel trapped in the pump at the point of impact cannot leak out from the end 34, because the poppet valve member 25 will have closed onto its seat 33. Similarly, no fuel can leak from the end 37n because the poppet valve 26 will have closed onto seat 32.

Figures 2 and 4 show an emergency valve for installation at the point 12 in Figure 2.

Referring to Figures 2 and 4, the construction of the valve body as two connected parts is the same as shown in Figure 3 and, therefore, similar reference numerals are used for these parts. The valve body part 21 is intended to be connected to the petrol dispensing pump while the other body part 22 is connected at its end 40 to the vapour recovery line 12. As will be seen from Figure 2, one valve operating member 41 is normally open, while the other member 42 is normally closed under the influence of a line closure spring 43. In normal use, vapour may flow through the valve from the delivery pump end 44, past the normally open valve member 41 and would normally have sufficient pressure above that prevailing in the vapour line 7 to open the valve 42, and flow back to the vapour recovery line.

Valve operating member 41 is attached to a shear bolt 45, whose other end 46 is secured to a boss portion 47 of the valve body component 22. A spring 48 urges valve 41 into its closed position, but movement is prevented by the shear bolt 45.

Shear bolt 45 includes a necked-down portion 49, which is aligned with the connection between the two valve body parts.

The valve works in a very similar way to that described with reference to Figure 3. In the event of serious impact damage to the delivery pump, the shear bolt 45 will sever at the break line 49, and this will immediately allow valve member 41 to close onto its seat. This will prevent any vapour escaping from the pump, and will also allow the two body parts of the valve to separate without applying any further stress to them. At the same time, valve member 42 will remain closed under the influence of its closure spring 43. Accordingly, no vapour can escape into the forecourt of the filling station from the vapour recovery line.

The valve shown in Figure 2 may also include a thermostat device which lifts the valve member 42 to permit vapour to flow into the vapour recovery line 2 if high ambient temperatures on the forecourt cause the pressure of vapour in the pump to rise.

Referring to Figure 4, this shows, in section, a modification to the lower part of the valve shown in Figure 2. In this modification, an eccentric cam 50 projects into the space just beneath spindle 51 of the valve member 42. Cam 50 is so adapted that by rotating the control end 52 of the cam, pressure can be applied to the end of the spindle 51, to close the valve 42 firmly onto its seat. A pressure test can then be made through a test port beneath the valve, using the technique and apparatus described in UK Patent Application No. 2265988 or by a similar method.

As can be seen from Figures 2,3 and 4, the valve body may be grooved for attachment by U-bolt fixing means, or other fixing, for through bolting into the base of the delivery pump and subframe.

Figure 5 shows a further embodiment of a shear valve for use as a vapour control valve 12 in the installation such as shown in Figure 1. The construction of the shear valve is similar to that of Figure 3 and comprises a cylindrical valve body 112 formed from two separable tubular parts 121 and 122. A tapered circular projection 138 on one part co-operates with a corresponding internal tapered face 139 on the other part to assist in centering or aligning the two parts when assembled. An'0' ring 124 provides a seal between the two parts. Parts 121 and 122 are held together solely by a shear bolt 127 having a weakening notch 136 at approximately its midpoint. In common with the embodiments of Figures 2 and 3, the only points of engagement of the two tubular parts are the peripheral tapering faces and the shear valve thus provides no resistance to separation under a lateral impact or turning movement, other than the frangible bolt 127. Also, it will be seen that the sole contact areas between the two separable parts 121 and 122 lie on or close to a plane A-B passing through the weakened portion 136, and constituting the shear line of the valve. This ensures that the two parts of the valve body will separate cleanly and there are no interengaging parts of the valve body which could interfere with the desired breakage of the boh 127 at the notch 136. Shear bolt 127 is received within tubular portions 128 and 129 of the parts forming the valve body. Valve members 125 and 126 are carried on opposite ends of the shear bolt and are secured by tension screws 135 and 136 which engage with internal threads formed in each end of the shear bolt. By tightening the tension screws, the valve members are urged towards each other, thereby tensioning the springs 130 and 131, as well as tensioning the shear bolt to some extent in tension. In the embodiment of Figure 5, the springs are of substantially equal tension. The separable parts of the valve are held individually in position by clamps 140 and 141. In the event that that the dispensing pump (which will be connected to the part 121 of the assembly) sustains damage sufficient to cause a minimum predetermined bending or shear force to the valve assembly, the shear boh will break cleanly, parts 121 and 122 will separate and the valve members 125 and 126 will be urged immediately against the corresponding valve seats 132 and 133 and seal the vapour lines to the pump and to the storage tank, thus preventing any escape of fuel vapour at the filling station forecourt. As shown in Figure 5, part 122 of the shear valve is connected to a fitting 150 which houses a vapour control valve 151. Valve 151 is held onto its seat by a light spring 152 which is designed to lift and allow vapour to flow back to the tank during normal operation of the dispensing pump.

Figures 6A and 6B illustrate one method of installing the shear valve in a delivery pump housing. A shear valve 50 comprising two separable parts 51,52 is secured to respective upper and lower frame members 53,54 by clamp bolts 55, 56,57 & 58 and saddle brackets 60,61. In order to ensure that the two separable parts 51,52 remain properly aligned while the shear valve parts are clamped to the frame members, alignment pins 62,63 are inserted in alignment holes in the saddle bracket parts 60A and 61A. This prevents any strain being exerted on the shear bolt 27 during the securing of the shear valve and the connection of the shear valve to the fuel delivery or vapour recovery line. Once the valve has been secured to the frame members and the connections made, the alignment bolts are removed. The valve may also incorporate in one of the separable parts a positive shut off valve.

Proper alignment and fixing of the shear valves into the supporting brackets of a delivery pump may also be facilitated by using a tool as shown in Figure 7, which has the same external dimensions as the shear valve body, and which carries markings to indicate the correct positions of the notch in the shear bolt and the positions of the upper and lower top faces of the clamps.

Claims (8)

1. CLAIMS 1. A valve for use in a fuel delivery system which comprises a valve body formed from two separable parts, a valve operating member in each part, at least one of which is normally in an open position, the separable parts being connected and the open valve operating member being held in its open position solely by a readily frangible tie member, whereby on sustaining a lateral impact to the valve, the tie member is severed, thereby causing the open valve operating member to close and said parts to separate.
2. 2. A valve as claimed in claim I wherein the tie member connects the normally open valve member in one valve body part to said other valve body part.
3. 3. A valve as claimed in claim 1 or claim 2 wherein the tie member has a weakened portion which is aligned with mating faces of said body parts.
4. 4. A valve as claimed in any one of the preceding claims wherein one of said valve operating members is normally held closed under a closing pressure, which yields to permit vapour from the fuel delivery system to flow through said normally closed valve member.
5. 5. A valve as claimed in claim 1 wherein both valve operating members are normally open and said tie member directly connects said valve operating members and holds them off their associated valve seats.
6. 6. A valve as claimed in claim 5 wherein the tie member has a weakened portion aligned with a plane of contact between said body parts, whereby breakage of said tie member allows both valve operating members to close.
7. 7. A valve as claimed in any one of the preceding claims wherein the tie member comprises a shear bolt having a reduced thickness in the region of the connection between said body parts.
8. 8. A fuel delivery installation which comprises a fuel dispensing pump connected to a fuel storage tank via a fuel supply line and a vapour recovery line, the vapour recovery line including a shear valve located in the base of the fuel dispensing pump, said shear valve comprising two separate valve body parts which are held together by a frangible tie member, a valve operating member being mounted at each end of the member and being normally in an open position, the arrangement being such that lateral impact to the valve causes the member to sever and said valves to be closed onto their respective seats by spring pressure.