OIL FREE SCREW COMPRESSOR

• US 20090016921A1
• Filed: 07/02/2008
• Published: 01/15/2009
• Est. Priority Date: 07/03/2007
• Status: Active Grant

• Current Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.)
• Original Assignee: Hitachi Industrial Equipment Systems Company Limited (Hitachi, Ltd.)
• Inventors: Fujimoto, Hideki, Nishimura, Hitoshi
• Granted Patent: US 9,394,906 B2
• Time in Patent Office: Days
• US Class Current: 418/201.100
• CPC Class Codes: F04C 18/16 with helical teeth, e.g. chevron-shaped, screw type for non-parallel axes of movement F04C18/48
• CPC Class Codes: F04C 2240/30 Casings or housings
• CPC Class Codes: F04C 2240/81 Sensor, e.g. electronic sensor for control or monitoring
• CPC Class Codes: F04C 2270/195 Controlled or regulated
• CPC Class Codes: F04C 29/02 Lubrication of machines or engines in general F01M; Lubricant separation separation in general B01D
• CPC Class Codes: F04C 29/04 Heating; Cooling of machines or engines in general F01P; Heat insulation heat insulation in general F16L59/00
• CPC Class Codes: F04C 29/12 Arrangements for admission or discharge of the working fluid, e.g. constructional features of the inlet or outlet
• CPC Class Codes: F28D 2021/0049 for lubricants, e.g. oil coolers for vehicles F28D2021/0089

Abstract

Provided is a highly reliable oil free screw compressor including a first sensor for detecting a temperature of lubrication oil, second sensors for detecting temperatures of intake air, and a cooling fan controller having a storage portion storing therein a set temperature of lubrication oil and a set temperature of intake air, and a computing portion for computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the lubrication oil, delivered from the first sensor, becomes higher than the set value of lubrication oil stored in the storage portion, and computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the intake air, delivered from the second sensor, becomes higher than the set temperature of the intake air, stored in the storage portion.

Claims

1. An oil free screw compressor comprising a compressor body having a pair of male and female screw rotors which are rotatable in a noncontact and nonlubricated manner, an air cooling type cooler for lubrication oil for the compressor, an air cooling type cooler for compressed air, and a cooling fan for feeding cooling air into the compressor body and the air cooling type coolers, characterized by:

a first sensor for detecting a temperature of lubrication oil,

a second sensor for detecting a temperature of intake air,

a cooling fan controller including a storage portion storing therein a set temperature of the lubrication oil and a set temperature of the intake air, and a computing portion for computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the lubrication oil, delivered from the first sensor, becomes higher than the set temperature of the lubrication oil stored in the storage portion, and for computing a control signal for increasing the speed of the cooling fan if a detected value of a temperature of the intake air, delivered from the second sensor, becomes higher than the set temperature of the intake air.

2. An oil free screw compressor as set forth in claim 1, characterized in that the speed of the cooling fan is controlled by an inverter exclusively used for the cooling fan.

3. An oil free screw compressor as set forth in claim 1, characterized in that the speed of the cooling fan is controlled by an inverter for the compressor,

4. An oil free screw compressor as set forth in claim 1, characterized in that the cooling fan controller receives temperatures inside and outside of the compressor unit so as to control the speed of the cooling fan.

5. An oil free screw compressor as set forth in claim 1, characterized in that the cooling fan controller receives a temperature in a control panel such as a starter panel, so as to control the speed of the cooling fan.