Solenoid plunger cushioning system for a washing machine balancing fluid valve

Abstract

A washing machine includes an out-of-balance correction system having a plurality of injector valves each having an associated solenoid element. Each of the injector valves is adapted to selectively inject a balancing fluid into a pocket carried by an inner tub to offset the out-of-balance condition. The valves are rapidly and repeatedly cycled to achieve a timed dispensing of the balancing fluid. To reduce the effects of the repeated cycling on the solenoid, a cushion element is mounted to a rear portion of a plunger carried within a solenoid coil. Additionally, a texturing process is applied to a pole piece arranged within the solenoid coil to establish a controlled leakage of air from a central portion of the cushion element once the plunger contacts the pole piece. With this arrangement, the service life of the injector valve is increased and proper control and timing of the injector valve is assured.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention pertains to the art of valves and, more particularly, to a solenoid plunger cushioning system for use in a balancing fluid injection valve for selectively dispensing a balancing fluid into a rotating inner tub of a washing machine. [0003] 2. Discussion of the Prior Art [0004] During operation of a washing machine, it is not uncommon for an inner tub or spinner, which is rotatably mounted within the washing machine, to become unbalanced due to a particular distribution of a load of laundry. During the course of a typical wash cycle, the inner tub is rotated at a relatively high or extraction speed to extract water absorbed by the laundry. If the laundry is unevenly distributed within the inner tub during the extraction phase, an out-of-balance condition will develop. This out-of-balance condition, when rotated at the extraction speed, can cause excessive vibration. [0005] Certainly, excessive vi...

AI Technical Summary

Benefits of technology

[0013] Certainly, injecting balancing fluid from stationary injectors into receptacles arranged about a spinning inner tub requires precise timing. Accordingly, in order to meet these stringent timing requirements, the injector valve must be operated rapidly, and repeatedly in order to achieve proper correction of the out-of-balance condition. Repeated operation of this type is extremely hard on internal components of the solenoid. Therefore, in accordance with one aspect of the invention, a cushion is mounted to an end portion of the solenoid plunger. In a more preferred form, a groove or annular ring is formed in the end of the plunger and sized to receive a resilient, elastomeric annular ring. Once in place, the annular ring reduces the effects of the repeated impacts between the plunger and a pole piece or end portion of the coil body.

[0014] In accordance with another aspect of the invention, the pole piece undergoes a texturing process to roughen the impact surface. Examples of acceptable texturing include cross-hatching, knurling, rough sanding and the placement of grooves in the surface. With this arrangement, a leakage path is provided for air trapped in a center portion of the annular ring. Preferably, leakage of air trapped between the end of the plunger and the pole piece is controlled through the particular distribution and geometry of the texturing applied to the surface of the pole piece. In this manner, deceleration of the plunger, and by extension, greater control of the dispensed balancing fluid is established.

[0015] In accordance with a still further aspect of the invention, an electric signal, sent to activate the solenoid is actively controlled through a control unit incorporated into the unbalance correction system. More specifically, the voltage applied to the solenoid coil is ramped or stepped to control the deceleration of the plunger. In other words, the initial activation voltage is held high, then, as the plunger nears the pole piece, the voltage is quickly reduced causing the plunger to slowly impact the pole piece. The control of the supply voltage, in combination with the plunger cushion and texturing of the pole piece, provides for a longer service life and, in addition, increases control over the injection of the balancing fluid.

Problems solved by technology

Repeated operation of this type is extremely hard on internal components of the solenoid.

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