This is a Continuation-In-Part of co-pending prior U.S. Patent Application Serial Number 331,797 filed April 3, 1989.

Background of the Invention

The present invention relates to a drain valve which is used to drain condensate from a wet tank used in conjunction with pneumatic braking systems on vehicles such as buses, trucks, truck trailers, trains, construction equipment and large recreational vehicles.

Pneumatic braking systems in vehicles exhibit the condensation of water, oil and other impurities during compression and subsequent cooling of the pressurized air which is employed to actuate air driven pistons for the movement of drums and discs in the braking system. The pressurized air is stored in a plurality of tanks after it has been compressed during which it cools resulting in the condensation of water vapor, oil and other impurities present therein including compressor lubricating oil and gasoline vapor, the vast majority of which condense and collect in the air storage tank immediately

connected to the compressor which known as the "wet tank." The condensate collected in the "wet" tank must be drained periodically to prevent its entrainment into the braking system with the potential for damage to or functional degradation of the system. In the current state of the art, drainage is performed manually by the vehicle driver opening a manually operable, gravity drain valve located at the bottom of the wet tank. Industry standard procedure calls for the driver to drain the wet tank each time the truck's engine is shut-off. There are numerous disadvantages to this prior practice.

Drivers rarely drain the wet tank each time the engine is shut off or even on a regular relatively frequent basis with the result that the braking system is frequently damaged or compromised. This is both dangerous and costly.

Additionally, the manually operated drain valve is frequently located in an inaccessable position beneath the truck which subjects the driver to exposure to grease and dirt. This discourages the driver from draining the wet tank even if he remembers* to so do.

It' is an object of this present invention to provide a reliable, wet tank drainage system that works automatically in conjunction with a vehicle's ignition system or other electrical system which is periodically energized or de-energized or otherwise generates an electrical signal. This eliminates human inattention and thereby greatly reduces the danger and costs associated with damaging or functionally compromising the braking system. Brief Description of the Drawings

FIG. 1 is a schematic, side elevational view of the system showing the drain valve of the present invention connected to the wet tank of a pneumatic brake system of a vehicle.

FIG. 2 is a perspective, side view of the drain valve showing the mounting bolts.

FIG. 3 is a perspective, exploded, partially sectional view of the drain valve along its longitudinal or operational axis.

FIGS. 4 and 5 are partially sectioned, side elevational views of the drain valve taken along lines 4 and 5 on FIG.2.

Detailed Description of the Preferred Embodiment

A preferred embodiment of the invention is shown in the drawings, wherein like reference characters designate like or corresponding parts throughout the several views.

Referring now to the drawings in detail, FIG. 1 is a schematic side, elevational view of a wet tank 1 wherein condensed moisture and other impurities collect and a secondary air tank 2 connected to the wet tank 1 through an air line or conduit 3 which is provided with a one-way or check valve 4 to prevent air from escaping from the secondary tank 2 to the wet tank 1 when it is vented to the atmosphere to drain. Condensed moisture and impurities accumulated in the wet tank 1 are drained through service line or conduit 5 at the bottom of the wet tank, through the drain valve 6 of the present invention, when open, to discharge through the drain line 28.

FIG.2 is a perspective, side view of the drain valve, 6, which is attached to any appropriate part of the vehicle by mounting bolts 7, 8. The drain valve 6 is controlled by an electrically operated

valve 10 which is operatively connected on one side to a source of air pressure through conduit 11 and on the other side to a pneumatic piston 9 having an external extension 12. Valve 10 is actuated by electricity from the vehicle's electrical system through its ignition switch 25 to contacts 26 and 27 on the valve 10. The contacts 26 and 27 may also be shrouded with insulating material to protect the electrical connection.

FIG.3, is a perspective, partially sectioned, exploded view of the drain valve 6, and shows the pneumatic piston 9 having the external extension 12 operatively engaged to a cylindrical drain valve piston 13 which carries two axially spaced-apart "0" rings 14, 15 thereon for water tight, axially slidable engagement within a conforming cylindrical, internal valve cavity 16 within the drain valve 6. The cavity 16 is open at the opposite ends of the valve 6. The valve 6 is provided with an inlet 17 in its top communicating with the internal cavity 16. The lowermost end of the service line 5 is connected to the inlet 17. The drain valve 6 is also provided with an outlet 18 in its bottom communicating with the cavity 16. The outlet 18 is spaced-apart from the inlet 17 along the long or operating axis of the valve 6.

The piston 13 is retained within the cavity 16 by a retaining ring 20 which closes the end of the cavity 16 end opposite the pneumatic piston together with an "0" ring 21 which receives and seals the extension 22 of the drain piston 13. The retaining ring 20 is secured to the drain valve 6 by cap screws 23. The cavity 16 is closed at its opposite end by the external portion 12 of the pneumatic piston 9. The extension 22 on the drain valve piston 13 carries

an axially mounted spring 24 which is compressible between the retaining ring 20 and an annular, radially extending shoulder 29 formed on the drain piston 13 within the cavity 16.

FIGS. 4 and 5 are partially sectioned, side elevational views of the valve 6 taken along lines 4, 5 in FIG. 2, and shows the operational position of the drain valve 6 when the ignition switch 25 of the vehicle is in the "on" position and the drain valve piston 13 is in a closed position at rest within the cavity 16 by virtue of the expansive pressure of the spring 24. In this closed position, the pneumatic piston is disconnected from the source of air pressure by means of the electrically operated valve 10 and the inlet 17 and outlet 18 are sealed from each other by the "0" ring 15. The "0" rings 14, 15, 21 may be made of rubber, or neoprene, or similar materials resistant to water vapor and contaminants.

When the ignition key 25 is in the "off" position, the valve 10 is electrically actuated by power from the vehicle's electrical system, through the ignition switch 25 to terminals 26, 27 on the valve 10. This in turn connects the pneumatic piston 9 to a source of air pressure, driving its piston extension 12 longitudinally against the drain piston 13 moving it to the open position shown in FIG 5. This opens the cavity 16 simultaneously to inlet 17 and outlet 18, thereby draining the wet tank 1 of accumulated liquid condensate and contaminants.

To close the drain valve 6, the ignition key is turned to the "on" position which closes the electrically operated valve 10 thereby disconnecting the pneumatic piston 9 from the source of air pressure. When the pneumatic piston 9 is disconnected from the source of air pressure, the

spring 24 again drives the drain valve piston 13 to the closed position shown in Figure 4. Means are provided for venting the pneumatic piston 9 when the air pressure valve 10 is closed. Such means are well-known in the art and need not be detailed further.

In the open position of the drain valve 6, when both the inlet 17 and outlet 18 are to the cavity 16, the condensate is discharged both by gravity and by escaping pressurized air from the wet tank 1 through the service line 5, the open inlet 17 to the cavity 16 and downwardly through the open outlet 18 to the waste line 28. When the ignition key 25 is turned on, so that the drain piston 13 is moved to its closed position by extension of the spring 24, the integrity of the pressurized air in the wet tank 1 and the brake system is maintained.

The extension 22 on the drain valve piston 13 extends beyond the drain valve 6 and can be manually driven to return the drain valve piston 13 to the "closed" position in the event that the spring 24 cannot close the valve 6 when its source of air pressure is disconnected by valve 10. This prevents such a malfunction of the drain valve 6 from preventing pressurization of the braking system.

It-has been found that the braking system is always fully drained, which precludes the liquid containing water vapor and other contaminants such as oil, gasline vapor, alcohol vapor, etc. from damaging the system, including the remote brake drums and other devices, particularly those devices, such as "0" rings and seals, which are made of rubber, neoprene, plastic and similar materials which are easily attacked by water and contaminants. One of the factors which helps to achieve this full drainage

result is that there is a purge of liquid contents and of pressurized air from wet tank 1 into the drain valve 6 because of the pressure differential between the pressurized wet tank 1 and the atmospheric pressure through the drain valve 6. Another factor which helps to achieve this full drainage result is that the drain valve 6 operates efficiently at all times, even in cold weather, because the air in the wet tank 1 is warmed by the air compressor and by braking action. The pressurized air goes in at approximately 95 psi to the wet tank 1 and shuts off at about 125 psi. Because of the direct service line 5 beween the wet tank 1 and the drain valve 6 into the cavity 16 between the two axially spaced-apart "0" rings 14, 15, the warm air is periodically forced downward through the service line 5 to warm the drain valve 6.

It has also been found that there is no accumulation of condensed liquid containing impurities in the secondary tank 2 because of the purging action of the drain valve 6.

In an alternative embodiment the condensed liquid containing impurities can be discharged from the drain valve 6 into a sump container for collection and storage, to be removed at a later time.

It will be understood that the present invention is not limited to the structure or components disclosed herein by way of example.

The scope of the present invention is limited only by the appended claims.