Portable, rotary vane vacuum pump with a quick oil change system

A portable vacuum pump for evacuating an air conditioning and refrigeration (AC/R) system to a pressure substantially below ambient, atmospheric pressure, said vacuum pump comprising:

• a housing with an interior bore and an oil inlet passage and an oil outlet passage through the housing in respective fluid communication with the bore of the housing,
• a lubricating oil system having an oil inlet arrangement and an oil return arrangement,
• said oil inlet arrangement including a primary oil reservoir, a secondary oil reservoir, and an oil pump mechanism positioned between the primary oil reservoir and the secondary oil reservoir and upstream of the bore of the pump housing to move oil from the primary oil reservoir to the secondary oil reservoir and to the bore of the pump housing while the vacuum pump is operating to evacuate the AC/R system with the primary oil reservoir and the secondary oil reservoir open to the atmosphere and at ambient pressure, said bore of the pump housing being at pressure less than ambient when the vacuum pump is operating to evacuate the AC/R system wherein oil is drawn into the bore of the pump housing along a first flow path upstream of the bore of the pump housing and downstream of the oil pump mechanism with said primary and secondary oil reservoirs open to the atmosphere and at ambient pressure,
• said oil return arrangement delivering oil via a second, return flow path from the bore of the pump housing and the secondary oil reservoir back to the primary oil reservoir with the primary and secondary oil reservoirs open to the atmosphere and at ambient pressure,
• said lubricating oil system further including at least first and second manually removable containers of oil and a switch mechanism selectively operable between first and second positions,
• said switch mechanism in said first position (a) placing the oil in the first container in fluid communication with the oil pump mechanism to become the primary oil reservoir and (b) placing the return flow path of the oil return arrangement in fluid communication with the first container to return oil from the secondary oil reservoir to the first container while isolating the second container from fluid communication with the oil pump mechanism and with the return flow path of the oil return arrangement and
• said switch mechanism in the second position (c) placing the oil in the second container in fluid communication with the oil pump mechanism to become the primary oil reservoir and (d) placing the return flow path of the oil return arrangement in fluid communication with the second container to return oil from the secondary oil reservoir to the second container while the vacuum pump is operating to evacuate the AC/R system, said switch mechanism in the second position additionally isolating the first container from fluid communication with the oil pump mechanism and with the return flow path of the oil return arrangement wherein said first container with the switch mechanism in the second position with the second container serving as the primary oil reservoir can be manually removed from the vacuum pump while the vacuum pump is operating to evacuate the AC/R system and with the primary oil reservoir of the second container and the secondary oil reservoir open to the atmosphere and at ambient pressure.