Table 17 — Initial and Final Unloading
Oil Pressures — 5F20, 5F30
| NO. OF | START TO | COMPLETELY | |
| UNLOAD | UNLOADED | ||
COMPR | CONTROLLED | |||
OIL PRESS. | OIL PRESS. | |||
| CYLINDERS | |||
| (psi) | (psi) | ||
|
| |||
5F20 | 1 | 19.8 | 13.0 | |
5F30 | 1 | 30.0 | 20.2 | |
2 | 19.8 | 13.0 | ||
|
5F40 THROUGH 5H86 (Fig. 7)
Major Elements of Capacity Control Systems:
1.Capacity Control Valve: Function is to raise or lower the control oil pressure to the hydraulic relay piston in response to refrigerant suction pressure. Increase in suction pressure increases control oil pressure in the hy- draulic relay.
2.Hydraulic Relay: Function is to feed lubrication oil from the oil pump at full pressure in sequence to one or more power elements. Relay is activated by control oil pressure from the capacity control valve.
3.Power Element: Supplies power to operate the valve lifting mechanism.
4.Valve Lifting Mechanism: Consists of a sleeve and push pin assembly around each controlled cylinder, designed to hold the suction valve open, or to permit the valve to remain in a normal operating position depending on its actuation by the power element.
Principle of Operation of the System — A decrease in suc- tion gas pressure, which necessitates a decrease in compressor capacity, causes the range spring to open the capacity control modulating valve. This allows control oil to relieve from the hydraulic relay and thus reduces control oil pressure in the relay. With reduced control oil pressure, the spring in the hydraulic relay moves a piston and thus lubrication oil from the oil pump is prevented from flowing to a particular deactivated power element. This relieves oil pressure from the power element allowing the spring in the power element to move the lifting fork and unload the cylinder. An increase in suction pressure reverses action and loads cylinders.
Fig. 7 — Capacity Control — 5F40, 60; 5H40, 46, 60, 66, 80 and 86
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