Patent Application
20200080561
The inventions described below relate to the field of vacuum pumps.
When the refrigerant tubing/piping of an Air Conditioning/Refrigeration (AC/R) system is exposed to atmosphere, air with water vapor and other contaminants may enter the tubing/piping. The moisture is highly damaging to refrigerant systems as it makes the refrigerant acidic which results in a corrosive environment that destroys system components and seals, and changes compressor oil to sludge. Cooling efficiency is degraded as pressures and temperatures vary greatly throughout the system. Compressor damage can occur and expansion valves can become clogged.
During installation of a new system or an open system repair, the refrigeration tubing/piping is exposed to ambient air, water vapor and/or other contaminants. After repair/installation and closure, the system needs to be cleared and checked for leaks to prevent loss of system efficiency over time. Before an AC/R system can be charged with refrigerant, the system must be arid, sanitary and sealed. The AC/R system should be evacuated to remove the water vapor and other contaminants and tested to ensure that a deep vacuum is held.
The most popular vacuum pump in the HVACR market is the rotary vane vacuum pump, which has a pump body/stator and a rotor made of one or more of cast iron, steel or powdered sintered steel. Cast iron, steel and powdered sintered steel are both high density materials that make vacuum pump systems very heavy. HVACR technicians often need to carry the vacuum pump system to the top of a building or some distance to reach the HVACR system. The typical vacuum pump system weight is about 30 pounds which represents a significant burden for HVACR technicians.
The devices and methods described below provide for a lightweight vacuum pump with either or both of the stator and rotor made of aluminum, aluminum alloy, sintered powdered aluminum or any other suitable lightweight material that has been subjected to high energy oxidation to treat and harden the wear surfaces. Plasma electrolytic oxidation (PEO) which may also be called electrolytic plasma oxidation (EPO), micro-arc oxidation (MAO) or spark discharge anodizing is a high energy surface treatment that forms a deep and hard oxide layer on the lightweight metal. Alternatively, a lightweight vacuum pump may be made of any suitable powdered metallurgy aluminum alloy and at least the wear and bearing surfaces may be hardened with a suitable high energy oxidation process.
Optionally, only the stator and bearing surfaces may be treated with a suitable high energy surface treatment. Another option is for only the insert sleeves and sidewalls for each stage of the vacuum pump, and/or rotor surfaces may be treated with a suitable high energy surface treatment such as those described above.
The lightweight vacuum pump may be submerged in an oil tank such that the oil covers the pump. The oil bath will help trap contaminants, seal the gaps between stages and lubricate the components. The oil bath also conducts the heat from the pump to the oil and convection will cool the oil tank and pump.
Optionally, vanes such as first stage vanes 8V and second stage vanes 9V may also be formed of a suitable lightweight metal such as aluminum, aluminum alloy or sintered aluminum powder. Optionally, the vanes can be formed of untreated polymer, carbon, graphite or other suitable material. In this case, the vanes 8V and 9V as well as vane slots 8S and 9S may also be treated with any suitable high energy oxidation process as discussed above.
The second stage 9 includes the stator or housing 9S, rotor 9R, vanes 9V, seal 24 and cap 9C. The stator 9S and rotor 9R are formed of aluminum, aluminum alloy or sintered aluminum powder. The volute 25 of the second stage is enclosed by first side or end wall wear surface 26, second side or end wall wear surface 27 (visible in
Optional oil pump 10 includes stator or housing 10S, vanes 10V and cap 10C. Vanes 10V engage a slot 36 in second stage rotor 9R. The wear surfaces of the oil pump volute, sides first and second side surfaces 37 and 38 as well as primary wear surface 40 are treated with any suitable high energy oxidation process such as PEO, EPO or MAO or any other suitable high energy oxidation process.
Optionally, the inner generally cylindrical walls of the first and second stage stators, primary wear surfaces 14 and 28 respectively may be provided as separate components such as hardened sleeves to be installed into an untreated lightweight housing. Similarly, the first and second side wear surfaces for the first and second stages, wear surfaces 12, 13, 26 and 27 as well as the first stage rotor bearing surfaces 17 and 18 along with the second stage rotor bearing surface 30 may be provided as separate components such as sleeves and plates that may be installed into an untreated lightweight housing or around an untreated lightweight rotor to achieve the wear resistance and the light weight as described. Any suitable lightweight material may be used for the housing, rotors and or vanes such as aluminum, aluminum alloy, sintered aluminum powder, other light metal such as zinc, magnesium or titanium or metal alloys of these or other light metals or any suitable polymer.
Alternatively, a lightweight vacuum pump may be made of any suitable powdered metallurgy aluminum alloy and at least the wear and bearing surfaces may be hardened with a suitable high energy oxidation process.
All the wear and bearing surfaces as well as the vanes and the rotor slots which are described above as treated with a high energy oxidation process should have a hardness of 500-3000 HV as measured by the Vickers hardness test.
As described above, the pump includes a stator having a cylindrical volute, a rotor rotatably disposed within the stator, and a vane coupled to the rotor and translatably disposed relative to the rotor. The stator has a cylindrical inner wall, a first end wall and a second end wall. The rotor has an outer cylindrical surface which may contact the cylindrical inner surface of the stator during rotation of the rotor. The vane has a sealing surface at a radial outer edge of said vane (the edge that scrapes the inner cylindrical surface of the stator during rotation). One or more of the stator, rotor or vane comprises a wear surface comprising aluminum, and at least one wear surface has a Vickers hardness in the range of 500 to 3000 HV. Each wear surface, or a subset of the wear surfaces, may have a Vickers hardness in the range of 500 to 3000 HV. The wear surfaces, or the entire component, may obtain this hardness through the POE, EPO, or MAO processes mentioned above. The pump, as described above, preferably comprises two stages, but the advantages of processing the wear surfaces with these processes may be obtained in a pump with one stage, or several stages.
The lightweight vacuum pump may also be made as an air-cooled, O-ring sealed aluminum vacuum pump which may also include an oil management system with a preferential vacuum relief system that allows air instead of the oil from the sump to be drawn back into the evacuated lines attached to the vacuum pump system. The oil management system also includes a primary oil reservoir with an illuminated sump for observation of the oil condition. The oil reservoir also includes a large oil inlet and outlet for rapid and safe oil changes even while the pump is operating.
The contents of our copending U.S. patent application Hong, Vacuum Pump with an Oil Management System, U.S. patent application Ser. No. 16/048,064 filed Jul. 27, 2018 is hereby expressly incorporated herein by reference in its entirety.
While the preferred embodiments of the devices and methods have been described in reference to the environment in which they were developed, they are merely illustrative of the principles of the inventions. The elements of the various embodiments may be incorporated into each of the other species to obtain the benefits of those elements in combination with such other species, and the various beneficial features may be employed in embodiments alone or in combination with each other. Other embodiments and configurations may be devised without departing from the spirit of the inventions and the scope of the appended claims.
This application claims priority to U.S. Provisional Application 62/729,199, filed Sep. 10, 2018.
| Number | Date | Country | |
|---|---|---|---|
| 62729199 | Sep 2018 | US |
