Pressure switch with adjusting cam of particular configuration

Claim 2

In a pressure-responsive switch assembly having a fluidpressure-responsive diaphragm, a switch arm operated by movement of said diaphragm, a pair of contacts selectively engageable by said switch arm depending on the position of said diaphragm, and biasing means for applying a variable biasing force on said diaphragm in opposition to the fluid pressure acting thereon, the improvement which comprises a cam having its periphery in camming engagement with said biasing means, said cam having a projection thereon arranged to depress said biasing means sufficiently to move said switch arm from engagement with one of said contacts to a reset position in which it engages the other of said contacts, said cam having a low point immediately before and a high point immediately after said projection in the direction of rotation of the cam, means for rotating said cam in one direction only, said cam providing gradual changes in the pressure on said baising means upon rotation thereof, along substantially its entire periphery, whereby rotation of said cam through one complete revolution serves to momentarily place said switch assembly in its reset position.

Claim 3

The switch assembly oF claim 1 in which said means for rotating said cam in one direction only includes a pawl and ratchet.

Claim 4

The switch assembly of claim 2 in which said ratchet is secured to said cam and is rotatable therewith.

Claim 5

A washing machine comprising a tub, inlet means for introducing water into said tub, solenoid means controlling operation of said inlet means, an agitator disposed in said tub, a motor arranged to drive said agitator, an adjustable pressure-responsive switch form sensing the level of liquid in said tub, said pressure-responsive switch including manually operable control means, a switch arm, a pair of contacts selectively engageable by said switch arm, the engagement of said switch arm with one of said contacts in a first position functioning to energize said solenoid means and introduce water in said tub, the engagement of said switch arm with the other of said contacts in a second position functioning to deenergize said solenoid means and energize said motor, a diaphragm responsive to the liquid level in said tub and arranged to move said switch arm into one of said two positions, biasing means acting on said diaphragm to set the operating point at which said arm engages said one or said other of said contacts, a cam having its periphery in camming engagement with said biasing means, said cam having a projection thereon arranged to act on said biasing means with sufficient pressure to cause said switch arm to move from engagement with said other contact to said one contact, said cam having a configuration such that it has a low point immediately before and a high point immediately after said projection in the direction of rotation of the cam, means coupled with said control means for rotating said cam in one direction only, said cam providing gradual changes in the pressure on said biasing means upon rotation thereof through a major portion of a 360* arc.

Claim 6

A washing machine comprising a tub, inlet means for introducing water into said tub, solenoid means controlling operation of said inlet means, an agitator disposed in said tub, a motor arranged to drive said agitator, an adjustable pressure-responsive switch form sensing the level of liquid in said tub, said pressure-responsive switch including manually operable control means, a switch arm, a pair of contacts selectively engageable by said switch arm, the engagement of said switch arm with one of said contacts in a first position functioning to energize said solenoid means and introduce water in said tub, the engagement of said switch arm with the other of said contacts in a second position functioning to deenergize said solenoid means and energize said motor, a diaphragm responsive to the liquid level in said tub and arranged to move said switch arm into one of said two positions, biasing means acting on said diaphragm to set the operating point at which said arm engages said one or said other of said contacts, a cam having its periphery in camming engagement with said biasing means, said cam having a projection thereon arranged to act on said biasing means with sufficient pressure to cause said switch arm to move from engagement with said other contact to said one contact, said cam having a configuration such that it has a low point immediately before and a high point immediately after said projection in the direction of rotation of the cam, means coupled with said control means for rotating said cam in one direction only, said cam providing gradual changes in the pressure on said biasing means upon rotation thereof through a major portion of a 360* arc.

Claim 7

The washing machine of claim 4 in which said means for rotating said cam in one direction only includes a pawl and ratchet.