Solenoid fuel drain valve

A solenoid fuel drain valve (2) comprising a valve body (4), having a drain hole (20) and an air inlet opening (22), a solenoid coil (10) and a piston, the drain hole (20) having a drain inlet (20) and a drain outlet (15); and the piston being arranged within the valve body (4) to be moveable between a closed condition, wherein the drain hole (20) and the air inlet opening (22) are sealed, and an open condition, wherein the drain hole (20) and the air inlet opening (22) are open, movement of the piston being controlled by the solenoid (10).

RELATED CASES

The present application claims priority to United Kingdom Patent Application Ser. No. 0216115.6; filed Jul. 11, 2002, the disclosure of which is expressly incorporated herein by reference.

BACKGROUND OF THE INVENTION

This invention relates to solenoid fuel drain valves, in particular, although not exclusively, to solenoid drain valves for use in automotive fuel systems.

Fuel systems, generally comprise a fuel filter to remove water and other contaminates from the fuel. The fuel filter is generally part of a closed system. It is preferable to periodically remove the water and other contaminates from the fuel filter.

This may be achieved using a manual fuel drain valve. The operator of a manual fuel drain valve periodically releases the water and other contaminates by rotating the drain valve. Water and contaminates can be released from the fuel filter by draining through a first hole in the valve as air enters the fuel filter through a further hole in the valve.

A manual fuel drain valve is inconvenient because the fuel filter is often positioned in an awkward location in an automotive engine and is not easily accessible.

As an alternative, solenoid activated fuel drain valves have been developed. Solenoid fuel drain valves are electrically operated. A solenoid fuel drain valve may be controlled automatically by, for example, an engine control system, or mechanically by, for example, activation of a switch by an operator.

To operate a solenoid fuel drain valve, a solenoid coil is activated to cause a plunger to be pulled from a closed position to an open position. In order to allow water and other contaminates to be released from the fuel filter the fuel system must be pressurised. In some arrangements, residual pressure from the fuel system provides enough pressure for the water and other contaminates to flow through the drain valve when opened by the solenoid. In other arrangements, it may be possible to mount the fuel filter below the fuel tank to create the required pressure difference. Otherwise, a means of pressuring the fuel system must be provided in addition to the solenoid fuel drain valve, in order to provide for drainage of the water and other contaminates through the valve when the valve in opened by the solenoid.

In automotive engines in particular, it is not always possible to arrange the fuel filter below the fuel tank, and provision of additional pressurisation means adds undesirable expense to the manufacturing and maintenance costs.

SUMMARY OF THE INVENTION

It is an object of preferred embodiments of the present invention to provide an improved solenoid fuel drain valve.

The present invention provides a solenoid fuel drain valve comprising a valve body, having a drain hole and an air inlet opening, a solenoid coil and a piston, the drain hole having a drain inlet and a drain outlet, and the piston being arranged within the valve body to be moveable between a closed condition, wherein the drain hole and the air inlet opening are sealed, and an open condition, wherein the drain hole and the air inlet opening are open, movement of the piston being controlled by the solenoid.

The valve body may be a unitary body. Alternatively, the valve body may comprise a plurality of units connected together for use thereof. For example, the valve body may comprise a solenoid housing and a solenoid adapter, which solenoid adapter is attached to the solenoid housing.

The valve body suitably defines an interior chamber, into which the drain hole and the air inlet opening open. The valve body suitably further comprises attachment means for connecting the solenoid fuel drain valve to a fuel filter for use of the valve. The valve body may comprise one or more torque limiter to prevent over compression of the valve body against a fuel filter during attachment thereto for use.

The valve body may further comprise an air passage, connecting the air inlet opening to an air source. The air source may be provided by venting the air inlet opening to the exterior of the valve body.

The valve body may comprise more than one air inlet opening. Provision of more than one air inlet opening advantageously facilitates draining in a non-horizontal orientation of the vehicle. Each air inlet opening may be connected to an air source by means of an air passage. Each air inlet opening may comprise a separate air passage, or two or more of the air inlet openings may share part at least of one air passage.

If the valve comprises a more than one air inlet opening, each of the plurality of air inlet openings is suitably spaced equidistantly from the others about the valve body.

It should be noted that reference to an air inlet opening, and air passage and an air source is not intended to limit the invention to use only with atmospheric air. As will be clear to a skilled person the invention could be used with any fluid, preferably a gas, which is suitable for use in the fuel filter.

The valve body may further comprise a drain passage, connecting the drain inlet to a drain outlet.

Part or all of the drain passage may be provided by a drain tube located within the valve body.

Suitably, in use of a valve according to the present invention, the valve is arranged such that the air inlet is located above the drain outlet.

The piston suitably comprises a rod and a head. The head may be attached to the rod. Alternatively, the head may be separate from the rod and moved by means of the rod.

The head is suitably adapted to provide a means for sealing at least one of the drain hole and the air inlet when the piston is in the closed condition. The head may be adapted to seal each of the drain hole and the one or more air inlet openings.

The piston may comprise two or more heads, each of which may be independently attached to or separate from the rod. For example, the piston may comprise two heads, one arranged to seal the drain hole and one arranged to seal the one or more air inlet openings when the piston is in the closed condition.

The valve may be adapted such that, in use, the drain valve and the one or more air inlet openings are simultaneously opened by movement of the piston from the closed condition to the open condition, and vice versa. Alternatively, the valve may be adapted such that, in use, the drain valve and the one or more air inlet openings are sequentially opened as the piston moves from the closed to the open condition, and vice versa.

The piston may be arranged in the valve body such that part at least of the rod extends through the drain hole. If the valve body comprises a drain passage, the piston is suitably arranged in the valve body such that part at least of the rod extends through part at least of the drain passage.

Suitably, a solenoid drain valve according to the present invention further comprises a solenoid armature of magnetisable material attached to the piston. Preferably, the solenoid armature is connected to the piston rod. The solenoid armature and the piston are suitably arranged such that energization and de-energization of the solenoid effects movement of the armature, which in turns causes movement of the piston. The armature is suitably located at least partly within the solenoid coil.

A valve according to the present invention may further comprise a solenoid stem of magnetisable material. The solenoid stem and the solenoid armature are suitably arranged within the valve such that energization of the solenoid coil causes a magnetic field to be induced in the solenoid stem and in the solenoid armature. In this embodiment, the solenoid armature is then attracted to the solenoid stem, and movement of the piston is effected.

A valve according to the present invention may further comprise biasing means to bias the piston into either the open or closed condition. In this case, the solenoid is then suitably arranged to generate sufficient force to overcome the biasing force following energization in order to facilitate movement of the piston.

The biasing means is suitably one or more springs. Any suitably form of spring may be used.

The one or more spring is suitably arranged to act against the head of the piston. If the piston comprises two or more heads, the valve preferably comprises one spring for each head.

A solenoid fuel drain valve according to the present invention may further comprise a retaining surface arranged to provide a surface against which the biasing means may act to provide the biasing force.

In use of a solenoid fuel drain valve according to the present invention, the piston is suitably in the closed condition when the solenoid coil is not energised. When the engine is not in operation, the valve can be opened to allow water and other contaminates to leave the fuel filter.

In use, the solenoid coil is preferably energised by the engine battery. Energization of the solenoid coil creates a magnetic field inside the coil. Generation of the magnetic field causes the piston to move within the valve body.

Movement of the piston effects opening of the drain hole and the one or more air inlet openings.

De-energization of the solenoid causes the piston to move from the open condition to the closed condition, and thereby causes the drain hole and the one or more air inlet openings to be closed.

A solenoid fuel drain valve may be used in conjunction with a water probe, which water probe is suitably positioned in the fuel filter and detects the level of water present in the fuel filter. The engine control system could then be set to activate the solenoid fuel drain filter, or to indicate to the operator that activation is due, when a pre-set level of water is detected in the fuel filter. Alternatively, the solenoid fuel drain valve can be set to operate periodically, as appropriate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS. 1 to 4show a solenoid fuel drain valve2having a valve body4comprising a solenoid housing6and a solenoid adapter8.

The solenoid housing6contains the solenoid coil10, and comprises a passage12therethrough, which provides part of the drain passage. A drain tube14is located within the passage12of the solenoid housing6. The drain tube14has a stepped conformation as shown inFIG. 1. The end of the tube14distal the solenoid adapter8provides a drain outlet15.

The solenoid adapter8is connected to the solenoid housing6by any suitable means, such as torque limiters and screws (not shown) connecting the solenoid housing6to a fuel filter bowl (not shown) with the solenoid adapter8sandwiched therebetween; a seal16is provided between the two parts of the valve body4.

The solenoid adapter8also comprises a passage18providing part of the drain passage. The passage18connects with the passage12of the solenoid housing6, when the solenoid housing6and the solenoid adapter8are connected together. Passage18also has a stepped conformation.

The end of the passage18distal the solenoid housing provides a drain inlet20.

The solenoid adapter8further comprises two air inlet openings22. Each air inlet opening22is connected to the exterior of the valve body4, by means of an air passage24.

The diameter of the air passages24is greater than the diameter of the air inlets22. An advantage of this arrangement is that is reduces the likelihood of the air passage24becoming blocked by any water or other contaminates that may pass through the air inlet opening22.

The solenoid adapter8defines an interior chamber26into which the drain inlet20and the air inlet openings22open.

The solenoid fuel drain valve2further comprises a piston having a rod28extending through the drain passage defined by passages12and18and drain tube14, and into the interior chamber26of the solenoid adapter8. The piston has two heads, one head comprising a head seal30attached to the rod28, and the other head, comprising a head cap31and a head seal32, separate from the rod28. The rod28has a flange50extending therefrom and engaging the first head seal30distal the solenoid housing6.

In the completely closed position, as shown inFIGS. 1 and 2, the first head seal30is in sealing contact with the drain inlet20and the second head seal32is in sealing contact with both of the air inlet openings22.

The first and second head seals30,32are maintained in the closed position by means of the biasing force applied thereto by helical springs34and36. One end of each spring34,36acts against a retaining device38. The other end of the first spring34acts against the piston rod28to bias the first head seal30into the closed position against the drain inlet20. The other end of the second spring36acts against the head cap31to bias the second head32into the closed position against the air inlet openings22.

The retaining device38suitably comprises a plate-like element with collet-like arms40extending therefrom for attachment of the retaining device38onto a corresponding ridge42of the solenoid adapter8. Preferably, the retaining device38comprises openings (not shown) therein which extend across substantially the whole surface of the retaining device38. This allows air entering the solenoid adapter8though the air inlet openings22in use, to pass through the retaining device38and into a fuel filter bowl (not shown), to which the device is attached, without causing a significant blockage.

The valve2further comprises a body of magnetisable material acting as a solenoid stem44located in the drain passage provided by passages12and18. In addition, a body of magnetisable material acting as a solenoid armature46is attached to the rod28of the piston, by, for example, an e-clip. The solenoid armature46is located further along the piston rod28with respect to the solenoid stem44distal the piston head seals30,32.

Seals are provided between the solenoid stem44and the drain tube14, between the solenoid stem44and the solenoid adapter8, between the drain tube14and the solenoid housing6, and on the exterior of the solenoid adapter8to seal between the solenoid adapter8and a fuel filter bowl when the valve2is located for use.

In operation of the valve ofFIGS. 1 to 4, the piston is in the closed position (as shown inFIGS. 1 and 2) when the solenoid coil10is not energised.

When the engine is not running, the valve2can be opened. To open the valve2, the coil10is energised, suitably by means of the engine battery. This causes a magnetic field to be induced in the solenoid stem44, and in the solenoid armature46.

The solenoid armature46is then attracted to the solenoid stem44and so the solenoid armature46moves towards the solenoid stem44. This movement of the solenoid armature46causes the rod28to move against the force of the first spring34and move the first head seal30out of sealing contact with the drain inlet20. Thus the drain inlet20is opened, as shown inFIG. 3.

The momentum of the solenoid armature46and piston, plus the increasing force as the distance between the solenoid armature46band the solenoid stem44reduces, causes the rod28to continue moving until the flange50of the rod28contacts the head cap31attached to the second head seal32(as shown inFIGS. 3 and 4). Continued movement of the rod causes the piston to move against the force of the second spring36and move the second head seal32out of sealing contact with the air inlet openings22. Thus the air inlet openings22are opened, as shown inFIG. 4.

When the solenoid coil10is de-energised, the induced magnetic field in the solenoid stem44and the solenoid armature46will disperse and the attraction between the armature46and the stem44will be overcome by the force of the first and second springs34,36.

The piston will therefore be forced back towards the closed position. The second head seal32will contact the air inlet openings22first and provide a sealing engagement therewith as maintained by the second spring36. Continued movement of the rod will cause the flange50to lose contact with the head cap31of the second head. Thereafter, the first head seal30will contact the drain inlet20and provide sealing engagement therewith as maintained by the first spring34.

FIGS. 5 and 6of the drawings show a second embodiment of the invention, comprising a solenoid fuel drain valve100having a solenoid adapter102, a piston104and a solenoid106.

The solenoid106may be an off-the-shelf product supplied by any manufacturer.

The solenoid adapter102screws into a bowl108of a fuel filter in use, but also has two connecting screws110fastening the solenoid106to it.

The piston104comprises a rod112and a head114attached to one end of the rod112. The head114is designed to create a sealing engagement with a drain inlet116and an air inlet118of the solenoid adapter102when the piston104is in the closed condition (as shown inFIG. 5). The piston104slides within a drain passage124extending through the valve body100from the drain inlet116to the drain outlet126.

The piston104further comprises a solenoid armature122attached to the end of the rod112distal the head114. A solenoid stem (not shown) is also provided.

The air inlet118is the opening of an air tube120that connects the air inlet118to the exterior of the valve100.

A spring128acts on the piston104to bias the piston into the closed condition with the head114in sealing engagement with the air inlet118and the drain inlet116.

When there is an applied voltage to the solenoid coil, a magnetic field is created, causing the piston104to be drawn towards the fuel filter bowl108against the force of the spring128, as shown inFIG. 6. Thus the seal between the piston head114and the air inlet118and the drain inlet116is broken.

Air is then drawn into the air tube120, through the air inlet118and into the filter bowl108. This breaks the air lock in the fuel system allowing fluid and other contaminates to leave the fuel bowl108into the solenoid adapter102and out of the drain outlet126.

The reason that air can enter into the system and the air lock is overcome is because of the positioning of the air inlet118in relation to the drain outlet126. The air inlet118is positioned higher than the lowest point of the drain tube. The difference in height creates a pressure head thus allowing air to enter the air tube120and fluid then to drain.

When the voltage across the coil is switched off, the magnetic field is removed. The force of the spring128then causes the piston104to return to recreate a seal with the air inlet118and the drain inlet116. This stops all fluid movement and the solenoid fuel drain valve100is closed.

In both embodiments of the invention as described above, seals are positioned above the drain hole and the one or more air inlet openings and the biasing springs act downwards onto the seal heads. The fluid draining from the filter will act downwards onto the seal heads.

However, it will be apparent to a person skilled in the art, that the seal head and spring arrangements could be reversed to act in the opposite direction. In which case, the seal head(s) would be located below the drain hole and/or the one or more air holes when the valve is arranged for use. Also, the biasing springs would act in the opposite direction, i.e. upwards into the flow of fluid that would drain from the fuel filter in use of the valve. In this case, the orientation of the solenoid armature and the solenoid stem would also need to be reversed, such that, upon energization of the coil, the armature moves downwards away from the drain hole and one or more air inlet openings, towards the solenoid stem.