In many fluid systems, there is a need to have both a pressure source (e.g., a pump) as well as a vacuum source (e.g., vacuum pump, vacuum generator, etc.). For example, in fluid recovery systems or fluid transfer systems, there is a need to collect a fluid from a first location (e.g., a main fluid system, a first fluid system, a fluid collection point) and move the fluid into a reservoir and then to evacuate the fluid from that reservoir either back to the main fluid system (i.e., a recovery system) or to a second fluid system (i.e., a transfer system). To accomplish this, a vacuum source draws the fluid into the reservoir and then a pressure source drives it out of the reservoir.
The following U.S. patents are various types of fluid systems using pressure sources and vacuum sources.
U.S. Pat. No. 2,400,651 (Marsh) discloses a liquid elevating system. A summary of the Marsh system 2 is shown in FIG. 1. The Marsh system 2 uses a shuttle valve 4 between an air supply 6, a reservoir 8 and a pressure inlet (P) of a vacuum generator 10, as well as an air-operated valve 12 between the reservoir 8 and a vacuum inlet (V) of the vacuum generator 10. A reservoir inlet check valve 16 and a reservoir outlet check valve 14 are also used. A float mechanism 20 inside the reservoir 8 controls the shuttle valve 4.
U.S. Pat. No. 2,522,077 (Wahl) discloses a tank truck. A summary of the pumping system 34 used in the Wahl truck is shown in FIG. 2. The pumping system 34 uses a pump (P, driven by a motor 36) to draw a vacuum on a reservoir 38 to pull liquid in, and a mechanical screw 40 coupled to another motor 42 to pump it out. Manually-operated input 44 and output 46 valves are also used, as well as an air inlet check valve 48. The system 34 is manually-operated.
U.S. Pat. No. 2,664,911 (Thompson) discloses a portable vacuum and pressure liquid tank truck. A summary of the pumping system 18 of the truck is shown in FIG. 3. The pumping system 18 uses a pump 20 (driven by a motor, M) to draw a vacuum or pressurize a reservoir 22; a separator 24 with a float valve 26 keeps fluid from getting into the pump 20. The pump 20 action (vacuum, or pressure) is based on the position of a valve 28 that is manually controlled. Manually-operated input 30 and output 32 valves are also used.
U.S. Pat. No. 3,315,611 (Thompson) discloses a portable vacuum and pressure liquid tank truck, and uses a pumping system similar to the pumping system disclosed in U.S. Pat. No. 2,664,911 (Thompson) but adds an air bleeder to the system. The bleeder line draws air into the tank along with the liquid during the vacuum stage, thus eliminating foam. During the pressure stage, pressurized air is mixed with the liquid in the tank, making it easier to pump.
U.S. Pat. No. 4,770,610 (Breckner) discloses a frail material slurry pump system 50. A summary of the Breckner system 50 is shown in FIG. 4. This system 50 uses a vacuum pump 52 (driven by a motor M) and combination valving (V.sub.P1 -V.sub.P3, V.sub.V1 -V.sub.V3,BV.sub.I and BV.sub.O) to pull a vacuum on a reservoir 56 and uses a compressor (not shown, but forms a part of the air supply) with the combination valving (V.sub.P1 -V.sub.P3, V.sub.V1 -V.sub.V3, BV.sub.I and BV.sub.O) to pressurize the reservoir 56. The BV.sub.I and BV.sub.O valves are a bladder type to prevent damage to the frail material being pumped. This combination valving (V.sub.P1 -V.sub.P3 with V.sub.V1 -V.sub.V3) controls the inlet BV.sub.I and outlet BV.sub.O bladder valves of the reservoir 56.
U.S. Pat. No. 4,828,461 (Laempe) discloses an apparatus for metering flowable materials in sand core making machines. A summary of the pumping system 58 used therein is shown in FIG. 5. The pumping system 58 works in a similar manner to the Marsh system 2 (FIG. 1) but includes two shut-off valves, 60 and 62, going into a vacuum generator 64, whereby the shut-off valve 60 is coupled to the pressure port (P) of the vacuum generator 64 and the shut-off valve 62 is coupled to the vacuum port (V) of the vacuum generator 64. In order to pressurize a reservoir 66, the pumping system 58 uses a third shutoff valve 68 (for dividing the air supply, while closing the upper shut-off valve 60). Reservoir inlet 70 and outlet 72 check valves are also used with the reservoir 66.
U.S. Pat. No. 5,451,144 (French) discloses an air-operated pump system 76. A summary of this pump system 76 is shown in FIG. 6. The system 76 primarily uses gravity to draw liquid in, whereby a vaccum (V) is available as an option to assist gravity. The system 76 utilizes two sources of air pressure: a main air supply 78 and an auxiliary air supply 80, the latter of which is fed to a reservoir 84 via flow restrictor 82. Two poppet valves 86 and 88 are used. An air-operated three-way valve 90 is controlled by the poppet valves 86 and 88. A quick-exhaust valve 92 is coupled between the three-way valve 90 and the reservoir 84. Inlet 94 and outlet 96 check valves are also used with the reservoir 84.
However, none of these references teach or suggest controlling the exhaust port of a vacuum generator for creating both a pressure source and a vacuum source.