Screw compressor with integral oil cooling

A screw compressor assembly through which a lubricant circulates in operation, comprising:

• a compressor section defining a working chamber in which a pair of screw rotors are mounted for rotation so as to compress a gas from asunction to a discharge pressure, said compressor section having surfaces that are exposed to a pressure less than discharge pressure and which require lubrication when said assembly is in operation;
• means for separating lubricant from the mixture of lubricant and gas discharged from said compressor section when said compressor section is in operation, the interior of said separating means defining a sump which is at discharge pressure and the difference in pressure between said sump and said surfaces which require lubrication causing lubricant to continuously circulate from said sump to said surfaces requiring lubrication when said compressor is in operation;
• a motor for driving said rotors, said motor being cooled by suction gas;
• and
• a motor housing section attached to said compressor section for at least semi-hermetically enclosing said motor, said motor housing defining a path for the flow of suction gas into said compressor section and around and through said motor for heading exchange therewith, said motor housing further defining an internal integral heat exchange structure which defines a passage in flow communication with said sump and with said surfaces requiring lubrication, said internal integral heat exchange structure having a surface in heat exchange contact with suction gas passing through said motor housing so that lubricant circulating through said passage is cooled by suction gas prior to its delivery from said sump to said surfaces requiring lubrication.

A compressor drive motor assembly, for a screw compressor assembly through which a lubricant circulates, the compressor assembly having both a lubricant sump which is at discharge pressure in operation and a compressor having locations which require lubrication, comprising:

• means for delivering compressor suction gas into the interior of said drive motor assembly;
• a motor drivingly connected to said compressor and disposed in said drive motor assembly so that said suction gas directed into the interior of said assembly is brought into heat exchange contact with said motor;
• a main motor housing disposed around said drive motor and attached to said compressor, said main motor housing defining a heat exchange portion connected for flow to both said lubricant sump and to said locations in said compressor which require lubrication;
• and
• an end cap attached to said main motor housing to semi-hermetically close said drive motor assembly around said drive motor, said end cap including an internal heat exchange portion which cooperates with said main motor housing heat exchange portion to define both a passage for the flow of lubricant passing from said sump to said locatiosn requiring lubrication and an integral heat exchange structure exposed to suction gas flow through said drive motor assembly so that suction gas flowing through said assembly is brought into heat exchange contact with lubricant flowing through said cooperatively defined flow passage when said compressor assembly is in operation.