Claims
- 1. An improved hot gas defrost system wherein shock damage to system components is prevented, comprising:
- a) a refrigerant compressor connected in closed circuit with a condenser and an evaporator by a pipe assembly;
- b) said pipe assembly including a first pipe segment connecting the compressor and the condenser, a second pipe segment connecting the condenser and the evaporator, and a third pipe segment connecting the evaporator and the compressor;
- c) a hot gas defrost pipe segment connected to said first pipe segment and the second pipe segment of said pipe assembly; and
- d) a hot gas defrost valve disposed in said hot gas defrost pipe segment;
- e) said hot gas defrost valve including means for opening said hot gas defrost pipe segment to a maximum extent to permit hot gas to flow therethrough, and means for reducing the pressure differential across said valve before said valve is opened to said maximum extent;
- f) said means for opening said hot gas defrost pipe segment to a maximum extent includes a valve body having an inlet port and an outlet port;
- g) a valve plug located inside said valve body and further being moveably situated inside a main valve seat also located inside said valve body;
- h) said valve seat being located between and in open communication with said inlet port and said outlet port;
- i) said means for reducing the pressure differential across said valve includes a first bleed passage connecting said inlet port to said outlet port; and
- j) means for completely opening or completely closing said first bleed passage.
- 2. The improved system of claim 1 further characterized in that:
- a) said means for reducing the pressure differential across said valve further includes a second bleed passage connecting said outlet port to a first chamber and providing an unobstructed path for fluid flow from said outlet port to said first chamber;
- b) said first chamber in communication with a first moveable member biased in a first position, whereby the build up of fluid pressure at said outlet port results in a build up of fluid pressure in said first chamber to a level sufficient to counteract said bias of said first moveable member whereby the fluid pressure in said first chamber acts to move said first moveable member against said bias to a second position;
- c) when in said second position said first moveable member opening a third bleed passage whereby fluid is transported from said inlet port into contact with a second moveable member whereby fluid pressure from said inlet port moves said second moveable member which moves said valve plug out of engagement with said valve seat, thereby opening said valve to said maximum extent.
- 3. The improved system of claim 2 further characterized in that said second moveable member includes;
- a) a first piston biased downward by said first moveable member against the bias of a biasing means when said first moveable member is in said first position, and biased upward by said biasing means when said first moveable member is in said second position;
- b) when biased upward, said first piston opening said third bleed passage connecting said inlet port with a second pressure chamber in communication with a second piston;
- c) said second piston being biased upward whereby the build up of fluid pressure in said second chamber to a level sufficient to counteract said second piston bias acts to move said second piston downward;
- d) said second piston in communication with said valve plug such that downward movement of said second piston initiates downward movement of said valve plug out of engagement with said valve seat.
- 4. The improved system of claim 1 further characterized by and including:
- a) a solenoid actuated valve for closing communication through said second pipe segment when said hot gas defrost pipe segment is opened;
- b) said solenoid actuated valve including means for increasing the fluid pressure downstream of said solenoid actuated valve and reducing the pressure differential across said hot gas defrost valve before said hot gas defrost valve is opened.
- 5. The improved system of claim 1 further characterized in that said means for completely opening or completely closing said first bleed passage includes a first solenoid operated needle-valve.
- 6. The improved system of claim 5 further characterized in that:
- a) said valve plug is moveable out of engagement with said valve seat by a piston within said valve body, said piston being movable in a cylinder which contains a compression chamber opposite the piston from said plus;
- b) a second bleed passage connecting said inlet port with said chamber;
- c) a second solenoid operated needle-valve in said second bleed passage for opening and closing fluid flow through said second bleed passage.
- 7. The improved system of claim 6 further characterized by and including:
- a) a timer connected to each of said solenoid valves and adapted, when hot gas defrost valve opening is called for, to initially cause opening of said first solenoid valve and then, after a predetermined delay, cause opening of said second solenoid valve.
STATEMENT OF RELATED APPLICATIONS
This application is a continuation-in part of a commonly-assigned co-pending U.S. patent application also entitled "IMPROVED SHOCKLESS SYSTEM AND HOT GAS VALVE FOR REFRIGERATION AND AIR CONDITIONING", having Ser. No. 07/417,927, abandoned and filed Oct. 6, 1989. The entire disclosure of the above application is incorporated herein by reference.
US Referenced Citations (4)
Continuation in Parts (1)
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Number |
Date |
Country |
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417927 |
Oct 1989 |
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