Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
319 words
A pilot operated valve assembly comprising a cylindrical housing, a piston in the housing dividing it into inlet and pilot chambers, a pilot valve in the housing end wall, a sealed bellows fixed on the other end wall and projecting towards the pilot valve, an actuating pin extending between the bellows and the valve and passing through the piston head, a spring inside the bellows urging the free end of the bellows towards the valve with a force which, when combined with the internal pressure in the bellows and the force exerted by the bellows, acts to seat the pilot valve when the pressure outside the bellows is below a predetermined value, a bleed hole through the piston head providing flow between the two chambers at a rate less than the flow rate through the pilot valve when the pilot valve is open a substantial amount and sufficient to equalize the pressures in the two chambers when the pilot valve is closed, a groove around the piston near the piston head, ports leading from the inlet chamber to said groove so inlet pressure will prevail at the groove and prevent flow from the pilot chamber between the piston and housing, a filter screen between the inlet chamber and the bleed hole and said ports to keep foreign matter therefrom, an inlet in said other end wall of the housing, an outlet in the side wall of the housing, a second spring acting on the piston to move it to a position in which it closes off the outlet when the pilot valve is closed and the chamber pressures are equalized but being overcome by the pressure differential across the piston head when the pilot valve is opened by reason of pressure in the inlet chamber exceeding said predetermined value and causing the bellows to collapse, said piston mOving to uncover the outlet when the second spring has been overcome.
Claim 2
Dependent Claim
319 words
A pilot operated valve assembly comprising a cylindrical housing, a piston in the housing dividing it into inlet and pilot chambers, a pilot valve in the housing end wall, a sealed bellows fixed on the other end wall and projecting towards the pilot valve, an actuating pin extending between the bellows and the valve and passing through the piston head, a spring inside the bellows urging the free end of the bellows towards the valve with a force which, when combined with the internal pressure in the bellows and the force exerted by the bellows, acts to seat the pilot valve when the pressure outside the bellows is below a predetermined value, a bleed hole through the piston head providing flow between the two chambers at a rate less than the flow rate through the pilot valve when the pilot valve is open a substantial amount and sufficient to equalize the pressures in the two chambers when the pilot valve is closed, a groove around the piston near the piston head, ports leading from the inlet chamber to said groove so inlet pressure will prevail at the groove and prevent flow from the pilot chamber between the piston and housing, a filter screen between the inlet chamber and the bleed hole and said ports to keep foreign matter therefrom, an inlet in said other end wall of the housing, an outlet in the side wall of the housing, a second spring acting on the piston to move it to a position in which it closes off the outlet when the pilot valve is closed and the chamber pressures are equalized but being overcome by the pressure differential across the piston head when the pilot valve is opened by reason of pressure in the inlet chamber exceeding said predetermined value and causing the bellows to collapse, said piston mOving to uncover the outlet when the second spring has been overcome.
Claim 3
Dependent Claim
48 words
A valve assembly according to claim 1 in which the weight of the piston is great enough to give the piston and the return spring a natural frequency of vibration below compressor induced pulsations in a refrigeration system and thereby avoid piston movement in resonance with such pulsations.
Claim 4
Dependent Claim
41 words
A valve assembly according to claim 1, including a friction member mounted in a cavity in the side of the piston, a low rate spring urging the friction member into engagement with the housing to impose a frictional resistance to movement.
Claim 5
Dependent Claim
36 words
A valve assembly according to claim 1, in which the outlet comprises plural circumferential slots with connecting webs between the slots, said webs being undercut to permit flushing entrained dirt from the skirt of the piston.