HEAVY-DUTY AIR COMPRESSORS
Compressors are used in pneumatic systems to provide requirements similar to those required by pumps in hydraulic systems. They furnish compressed air as required to operate the units of the pneumatic systems.
Even though manufactured by different companies, most compressors are quite similar. They are governed by a pressure control system that can be adjusted to compress air to the maximum pressure.
Compressor Design
The compressor unit may be of the reciprocating, rotary, or screw design.
The reciprocating compressor is similar to that of an automotive engine. They may be air-or liquid-cooled. As the pistons move up and down, air flows into the cylinder through the intake valve. As the piston moves upward, the intake valve closes and traps air in the cylinder. The trapped air is compressed until it exceeds the pressure within the collecting manifold, at which time the discharge valve opens and the compressed air is forced into the air manifold (fig. 3- 51). The reciprocating compressor is normally connected to the engine through a direct coupling or a clutch. The engine and compressor are separate units.
The rotary compressor has a number of vanes held in captive in slots in the rotor. These vanes slide in and out of the slots, as the rotor rotates. Figure 3-52 shows an end
Notice in figure 3-52 the variation in the clearance between the vanes and the bottom of the slots, as the rotor revolves. The vanes divide the crescent-shaped space between the offset rotor and the pump casing into compartments that increase in size, and then decrease in size, as the rotor rotates. Free air enters each compartment as successive vanes pass across the air intake. This air is carried around in each compartment and is discharged at a higher pressure due to the decreasing compartment size (volume) of the moving compartments as they progress from one end to the other of the crescent-shaped space.
The compressor is lubricated by oil circulating throughout the unit. All oil is removed from the air by an oil separator before the compressed air leaves the service valves.
Compressors are used in pneumatic systems to provide requirements similar to those required by pumps in hydraulic systems. They furnish compressed air as required to operate the units of the pneumatic systems.
Even though manufactured by different companies, most compressors are quite similar. They are governed by a pressure control system that can be adjusted to compress air to the maximum pressure.
Compressor Design
The compressor unit may be of the reciprocating, rotary, or screw design.
The reciprocating compressor is similar to that of an automotive engine. They may be air-or liquid-cooled. As the pistons move up and down, air flows into the cylinder through the intake valve. As the piston moves upward, the intake valve closes and traps air in the cylinder. The trapped air is compressed until it exceeds the pressure within the collecting manifold, at which time the discharge valve opens and the compressed air is forced into the air manifold (fig. 3- 51). The reciprocating compressor is normally connected to the engine through a direct coupling or a clutch. The engine and compressor are separate units.
The rotary compressor has a number of vanes held in captive in slots in the rotor. These vanes slide in and out of the slots, as the rotor rotates. Figure 3-52 shows an end
Notice in figure 3-52 the variation in the clearance between the vanes and the bottom of the slots, as the rotor revolves. The vanes divide the crescent-shaped space between the offset rotor and the pump casing into compartments that increase in size, and then decrease in size, as the rotor rotates. Free air enters each compartment as successive vanes pass across the air intake. This air is carried around in each compartment and is discharged at a higher pressure due to the decreasing compartment size (volume) of the moving compartments as they progress from one end to the other of the crescent-shaped space.
The compressor is lubricated by oil circulating throughout the unit. All oil is removed from the air by an oil separator before the compressed air leaves the service valves.
posted by zulaf at 7:30 PM
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