ENCLOSURE FOR USE OF PRIME MOVER IN A HAZARDOUS ENVIRONMENT

A prime mover assembly is suitable for use in a hazardous environment. The prime mover assembly includes a hazardous rated enclosure, a non-hazardous rated prime mover disposed in the enclosure, and a gland assembly extending through the enclosure in communication with the prime mover. The gland assembly provides power and instrumentation through the enclosure to the prime mover.

BACKGROUND OF THE INVENTION

The invention relates to the use of prime movers in a hazardous environment and, more particularly, to a prime mover assembly that is suitable for use in a hazardous environment.

The use of prime movers (e.g., diesel engines or electric motors) in a hazardous environment such as underground mining is closely regulated for safety concerns including, for example, engine emissions, explosions, etc. The use of diesel powered equipment in underground mining has grown steadily since the 1960's. Regulations address potential concerns with regard to health effects related to operating diesel engines in underground environments. Hazardous rated prime movers are consequently considerably more expensive than non-hazardous rated counterparts.

In order to be usable in a hazardous environment, all electrical components (engine control modules/engine control units, fuel injectors, sensors, etc.) must be either explosion proof or intrinsically safe. Also, an external temperature of the engine should not exceed 302° F. Typically, to meet these limitations, manufacturers go through great measures to keep the temperatures down and often have to significaly derate the engine's output horsepower. It would be desirable to enable the use of a standard components (i.e., non-hazardous rated) in a hazardous environment.

SUMMARY OF THE INVENTION

By placing a component such as an engine in a cooled enclosure, it is not necessary to keep the temperatures of the exhaust manifold, cylinder head, and turbo charger below 302° F. Rather, only the external temperature of the enclosure and the final exhaust have temperature limitations. Embodiments described herein relate to a prime mover assembly utilizing non-hazardous rated prime movers and other components in a hazardous rated enclosure. With this structure, the less costly non-hazardous rated prime movers can be safely used in hazardous environments.

In an exemplary embodiment, a prime mover assembly is suitable for use in a hazardous environment. The prime mover assembly includes a hazardous rated enclosure, a non-hazardous rated prime mover disposed in the enclosure, and a gland assembly extending through the enclosure in communication with the prime mover. The gland assembly provides power and instrumentation through the enclosure to the prime mover. In one arrangement, the enclosure comprises a double wall construction. The assembly may further include a coolant in a space defined by the double wall construction. The enclosure may include an opening through which an output shaft of the prime mover is positioned. The output shaft may be supported by a bearing.

In one embodiment, the prime mover may be an electric motor. In this context, the electric motor may be a liquid cooled electric motor, where the enclosure includes a double wall construction. The prime mover assembly may also include a cooling circuit that directs a coolant through the motor and through a space defined by the double wall construction. The cooling circuit may include an outboard radiator.

In another embodiment, the prime mover may be a diesel engine. In this context, the enclosure may include a double wall construction and a coolant in a space defined by the double wall construction. The assembly may further include a cooling circuit and a pump that circulates the coolant. The cooling circuit may further include an outboard radiator. The prime mover assembly may also include an exhaust circuit and a catalyst, where the exhaust circuit is configured to route engine exhaust through the catalyst before entering the enclosure. An exhaust system includes a manifold, a turbocharger, and the catalyst, where the exhaust system is insulated from the engine. A spark arrestor may also be provided in the exhaust system. An air circuit supplies air to the engine, and the air circuit draws air through an air filter, through the enclosure, through the spark arrestor and to the engine.

In another exemplary embodiment, the prime mover assembly includes a hazardous rated enclosure including a double wall construction; a non-hazardous rated prime mover including one of an electric motor and a diesel engine; a gland assembly extending through the enclosure in communication with the prime mover, where the gland assembly provides power and instrumentation through the enclosure to the prime mover; and a coolant in a space defined by the double wall construction.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1is a perspective view of a prime mover assembly10suitable for use in a hazardous environment.FIGS. 2-4are side, plan and end views of the assembly, respectively. The assembly includes a hazardous rated enclosure12that houses a non-hazardous rated prime mover14such as an electric motor or a diesel engine. A gland assembly16extends through the enclosure12in communication with the prime mover14. The gland assembly16is preferably a standard MSHA approved gland assembly that provides power and instrumentation through the enclosure12to the prime mover14.

As shown, the enclosure12may be provided with a double wall construction18, which defines a coolant chamber in the space of the double wall construction. More specifically, the enclosure12defines a cooling circuit20that directs a coolant through the prime mover14and through the space defined by the double wall construction18. In one embodiment, the cooling circuit further includes an outboard radiator22.

An output shaft24of the prime mover14extends through an opening in the enclosure12and is preferably supported via a bearing26or the like. The diametric clearance between the shaft24and the enclosure12does not exceed clearance limitations specified by regulations. Additionally, the length of a flame path is greater than a minimum length specified.

In one configuration, the prime mover14is a standard electric motor (i.e., non-hazardous rated). Heat from the motor is transferred from the motor to the enclosure12, through the enclosure12and dissipated to atmosphere.

In an alternative construction, with reference toFIG. 6, the electric motor is a liquid cooled electric motor41including an output shaft45and an output shaft bearing44. The coolant in the cooling circuit can be circulated through the motor and the enclosure42via motor coolant lines47. Heat from the motor cooling jacket46can transfer from the coolant to the enclosure and is dissipated to atmosphere. Additional heat rejection capacity can be provided via an outboard radiator (e.g., radiator22—seeFIG. 1) fitted to the system.

In an alternative arrangement, the prime mover14is a standard diesel engine (i.e., non-hazardous rated). The enclosure for the diesel engine may be provided with a removable cover (not shown). The removable cover may also be cooled with the coolant. A suitable coolant may be ethylene glycol, antifreeze, or the like.

With reference toFIG. 5, the assembly may further include an exhaust circuit and a catalyst32as part of an exhaust cooling system28. The exhaust circuit is configured to route engine exhaust through the catalyst32before entering the enclosure. The prime mover assembly may also include an exhaust system with a manifold34, a turbocharger36, and the catalyst32. The exhaust system is insulated from the engine. A spark arrestor38may also be provided in the exhaust system. An air circuit supplies air to the engine. The air circuit draws air through an air filter, through the enclosure, through the spark arrestor38into the engine. In one arrangement, the floor of the enclosure is provided with tubing30between the inner and outer walls of the double wall construction18, and the coolant is circulated around the tube30. The coolant may be circulated via a pump through the external radiator22. This tube transfers the heat from the exhaust gases through the exhaust tube and into the coolant, reducing exiting exhaust gas temperature. A majority of the engine heat can be removed using the engine cooling system. The remaining engine heat will be transferred to the coolant through the interior enclosure wall.

FIG. 7is a perspective view of an explosion proof capacitor box51. The box51houses a capacitor56and includes a double-wall construction with a lid52. Also included are a cable entry53and a coolant port54. A coolant55is provided in the space defined by the double wall construction. The capacitor box allows the use of several different battery chemistries (e.g., lithium chemistries, sodium chemistries, etc.) that have not previously been rated for hazardous environments or otherwise explosion proof. As a result, a non-explosion proof or non-intrinsic safe battery maintenance system (BMS) can be used, which reduces manufacturing costs. Additionally, the capacitor box allows battery charging in the hazardous environment. Typical lead acid batteries can only be charged outside of a hazardous environment. Still further, the construction provides for temperature control of the battery or capacitor and serves to protect the battery or capacitor. Moreover, the box allows the use of non-hazardous capacitors as a source of energy to either assist a main energy source or to be used as an energy source without going through the trouble and expense of manufacturing a hazardous capacitor.

The ability to use non-hazardous rated prime movers and other components in a hazardous environment can result in considerable cost savings. Additional features provide for dissipation of exhaust and heat generated by the prime mover.