Patent Application
20210324859
The present disclosure relates to compressors, and more particularly to lubrication systems for oil flooded screw compressors.
Oil flooded screw compressors typically include a set of rotors or screws that require fluid (e.g., oil) to seal between the rotors and to remove heat generated during compression. The rotors are supported on bearings that also typically require lubrication. Often, the required oil is supplied by an air/oil separator tank. Pressurized air discharged from the compressor flows into the separator tank, where entrained oil is separated from the air and collected in the tank. The separator tank is maintained at an elevated pressure while the compressor is operating, thereby driving oil to the compressor.
Some machine operations (e.g., down-the-hole hammer drilling) require high air pressure (e.g., at or above 175 psi, and up to 500 psi in some cases) to operate a tool such as a drill bit hammer. Since the air compressor oil lubricating system uses air pressure to drive oil through oil coolers, all system components must be able to withstand the maximum operating pressure used plus a safety margin. As larger tools are developed and implemented, the maximum operating pressure increases, thereby requiring an increase in the size and complexity of cooling circuits that can withstand these operating pressures and still provide adequate cooling. Designing and fabricating large coolers that are capable of withstanding high operating pressures is difficult, and in some cases not economically feasible.
In one independent aspect, an industrial machine includes a working tool; an air supply system for supplying pressurized air for operating the tool, the air supply system including an air compressor supplying pressurized air at an output; a drive system for driving at least the air compressor; and a lubrication system for supplying lubricant to the air compressor. The lubrication system includes a reservoir configured to support lubricant, the reservoir configured to receive pressurized air from the air compressor; and a motor operably coupled to the drive system and configured to receive pressurized lubricant, flow of lubricant driving the motor to transmit power to the drive train in at least one operating condition.
In another independent aspect, a lubrication system is provided for supplying lubricant to an air compressor. The air compressor is driven by a drive system. The lubrication system includes a separator reservoir configured to support lubricant and configured to receive pressurized air from the air compressor, the separator reservoir configured to separate lubricant from the air received from the air compressor; and a motor operably coupled to the drive system and configured to receive pressurized lubricant. The motor is configured to transmit power to the drive system in at least one operating condition.
In yet another independent aspect, a lubrication system is provided for supplying lubricant to an air compressor for a drill. The air compressor is driven by a drive system. The lubrication system includes a separator reservoir configured to support lubricant and configured to receive pressurized air from the air compressor, the separator reservoir configured to separate lubricant from the air received from the air compressor; a cooler configured to reduce a temperature of the lubricant being driven to the air compressor; and a motor operably coupled to the drive system and configured to receive pressurized lubricant. The motor is configured to transmit power to the drive system in a first mode in which pressure of the air in the reservoir is sufficient to drive the lubricant from the reservoir through the motor. The motor is configured to be driven by the drive system to drive the lubricant in a second mode in which pressure of the air in the reservoir is insufficient to drive the lubricant from the reservoir and through the motor.
Other aspects of the disclosure will become apparent by consideration of the detailed description and accompanying drawings.
Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.
The present disclosure relates to a system for cooling and/or lubricating an air compressor. The system includes a regenerative circuit that is operable to reduce pressure of the cooling fluid/lubricant and is capable of capturing energy from the cooling fluid/lubricant to supplement a drive train, thereby increasing reliability and safety, lowering cost, and reducing power consumption.
An air compressor 100 is supported by the base 18 and is operable to generate compressed air that may be used, for example, for flushing bit cuttings from the bottom of the borehole to the surface. A lubrication system 200 is also supported by the base 18 and is operable to provide oil to the air compressor 100, as described below.
As shown in
The stator housing 130 includes an air inlet port 134 and an air outlet port 138. The main rotor 114 has helical lobes 142 and grooves 146 along its length, while the secondary rotor 122 has corresponding helical lobes 150 and grooves 154. Air flowing in through the inlet port 134 fills spaces between the helical lobes 142, 150 on each rotor 114, 122. Rotation of the rotors 114, 122 causes the air to be trapped between the lobes 142, 150 and the stator housing 130. As rotation continues, the lobes 142 on the main rotor 114 roll into the grooves 154 on the secondary rotor 122 and the lobes 150 on the secondary rotor 122 roll into the grooves 146 on the main rotor 114, thereby reducing the space occupied by the air and resulting in increased pressure. Compression continues until the inter-lobe spaces are exposed to the air outlet port 138 where the compressed air is discharged.
The illustrated compressor 100 is a single stage compressor; however, in other embodiments, the compressor 100 may have multiple stages. In some embodiments, the compressor 100 has a maximum output pressure at the air outlet port 138 of 500 psi. In other embodiments, the compressor 100 has a maximum output pressure at the air outlet port 138 less than 500 psi. In other embodiments, the compressor 100 has a maximum output pressure at the air outlet port 138 between 200 psi and 500 psi. In some embodiments, the compressor 100 has a maximum discharge volume of 3,800 cubic feet per minute (CFM). In other embodiments, the compressor 100 has a maximum discharge volume less than 3,800 CFM. In other embodiments, the compressor 100 has a maximum discharge volume between 1,000 CFM and 3,800 CFM.
The illustrated lubrication system 200 includes an air compressor receiver tank 212 and a cooler 216. These components are coupled together by fluid transfer components, such as piping, valving, and/or metering devices. It should be understood that the arrangement, selection, and number of fluid transfer components may be varied as would be understood by one of ordinary skill in the art. In the illustrated embodiment, the receiver tank 212 receives (either directly or indirectly) pressurized air from the air compressor and is a separator tank capable of separating lubricant from the pressurized air.
In the illustrated embodiment, a motor 222 (e.g., a fixed displacement hydraulic motor) is positioned between the receiver tank 212 and the cooler 216. The motor 222 is coupled to the drive train 42, and operation of the motor 222 provides additional power to the drive train 42. That is, the motor 222 is capable of transmitting power to the drive train 42. During operation, air pressure in the tank 212 may drive lubricant from the tank 212 and to the air compressor 100, through the motor 222 and cooler 216. In some conditions, the fluid drives the motor 222, transmitting some power back to the drive train 42. The power transmitted to the drive train may be in the form of rotational energy. In addition, the pressure of the fluid leaving the motor 222 is reduced before passing through the cooler 216.
Operational air pressure in the air tank 212 pushes hot lubricating oil from the air tank 212 to the motor 222 via connecting hoses and/or tubes. The motor 222 is connected to the air compressor prime mover drive train 42. As the prime mover 46 rotates, the motor 222 rotates at a speed proportional to the prime mover 46 and driven air compressor 100, thus ensuring lubricant flow from the air tank 212 to the air compressor 100. In some operating conditions (e.g., when operational system pressure is high or above a threshold), the motor 222 is driven by flow of the pressurized lubricant. As the lubricant drives the motor 222, the pressure of the lubricant is reduced at the motor outlet as the potential energy of the lubricant is converted into rotational energy of the motor 222 that is transmitted back into the prime mover drivetrain 42. Unlike other types of pressure-reducing devices (e.g., valves and orifices), the lubrication system 200 captures energy that is not necessary for cooling and supplies it back to the drive train 42. In one embodiment, an air system operating at 500 psi that requires an oil flow of 100 gallons per minute for cooling can regenerate 17.5 horsepower back into the drivetrain (minus inefficiencies) when the motor outlet to the oil cooler is 200 psi. The operation of the motor 222 (including the conditions in which it is activated to transmit power to the drive train 42) may vary depending on the operating conditions of the industrial machine and the lubrication system.
Furthermore, the lubricant pressure exiting the motor 222 is reduced, thereby enabling the system 200 to be operated with components having a lower pressure rating. Among other things, the use of lower-rated components reduces cost, increases reliability (e.g., due to less system fatigue), and increases safety.
As the operational air pressure in the air tank 212 decreases (e.g., when the pressure is relatively low), the need for lubricant for the air compressor 100 decreases. In some embodiments, the motor 222 is capable of transitioning to operating as a lubricant pump in some operating conditions (e.g., when operational system pressure is low or below a threshold). The pump/motor 222 may be driven by the drive train 42 to ensure an adequate flow to the air compressor 100 for cooling and lubrication. That is, in some embodiments the connection between the drive train 42 and the motor 222 permits power transmission in two directions (i.e., the connection is bi-directional). The threshold at which the pump/motor 222 transitions (including the conditions in which it is activated to transmit power to the drive train 42 or receive power from the drive train 42) may vary depending on the operating conditions of the industrial machine and the lubrication system. In other embodiments, the motor 222 may act as a motor only, regardless of the system pressure. Stated another way, in some embodiments, the motor 222 may operate in a single mode as a motor transmitting power to the drive train 41; in other embodiments, the motor 222 may be a pump/motor that operates as a motor in a first mode and operates as a pump in a second mode.
The system 500 includes a variable displacement hydraulic motor 522 positioned between a tank 512 and a cooler 516. The output requirements of the air system can vary, and often the speed of a compressor 400 must be adjusted accordingly. Changes in the speed of the compressor 400 impacts the flow of lubricant. The motor 522 can be adjusted to vary the amount of displaced fluid to match system flow and allow maximization of energy return to the drive train 542. In addition, motor displacement can be adjusted to control outlet pressure from the motor 522, thereby limiting pressure of the fluid passing to the cooler 516.
The system 800 includes a motor 222 positioned between a tank 812 and a cooler 816. In addition, a variable orifice 824 is positioned in parallel with the motor 222. The variable orifice 824 reduces the effects of pressure and flow fluctuations, thereby increasing the working life of the cooler 816 and the motor 222.
As shown in
The system 1100 includes a motor 222 positioned between a tank 1112 and a cooler 1116. In addition, a pressure reducing valve 1130 and relief valve 1134 are positioned downstream of a fixed displacement motor 222. The valves 1130, 1134 permit greater fluctuations in pressure and flow while also protecting the cooler 1116. In addition, the valves 1130, 1134 reduce constraints on the size of the motor 222, permitting greater flexibility in selection of the motor 222.
As shown in
Although the disclosure has been described in detail with reference to certain embodiments, variations and modifications exist within the scope and spirit of one or more independent aspects as described. Various features of the disclosure are set forth in the following claims.
This patent application claims the benefit of co-pending, prior-filed U.S. Provisional Patent Application No. 63/013,334, filed Apr. 21, 2020, the entire content of which is hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| 63013334 | Apr 2020 | US |
