Thomas Industries, Inc.

Thomas R Hetzel

Charles E LaBelle

Roy J Rozek

David A Bramstedt

A wear shield attached to a piston in a piston type compressor cushioning impact and reducing friction between the piston and a valve which opens in a direction toward the piston. During some conditions of operation, without the wear shield, a piston can impact the opening valve, which opens interior of a cylinder which holds the piston. The wear shield installed between the piston and the opening valve reduces wear on the piston and on the valve, and also reduces operating noise.

Noise reducing wear shield for piston face

A seal and retainer assembly for an air compressor piston includes a cup-shaped seal with its marginal edge extending at an angle relative to the cylinder wall, the seal having a notch extending circumferentially at the base of its marginal edge defining a hinge which allows pivoting of the marginal edge relative to the main body portion of the seal which is clamped to the piston. A head plate includes an air intake port for communicating the compression chamber with an air inlet and a discharge port for communicating the compression chamber with a compressed air discharge outlet, each of the ports having a flexible spring closure member cooperating with an inclined valve seat to allow the ports to be open whenever the compressor is shut off.

Piston cup and cylinder assembly

An air compressor has a low torque motor driven piston of the rocking rod type which operates in a cylinder with a closed head containing a discharge check valved port to a compressed air receiving chamber. The piston contains an intake port provided with a thin flexible metal spring closure strip which is inclined at a small angle to the valve seat about said intake port to open on the downstroke of the piston, close on the upstroke thereof and remain open when at rest to facilitate start and restart of the air compressor.

Air compressor with ramped intake valve

The present invention is applicable to wobble piston compressors having overrun intake ports and being driven by a motor of low starting torque. In such a layout the vacuum created in the compression chamber upon initial motion of the piston from top standstill (at the outer end of the cylinder) may be great enough to stall the motor of low horsepower. The present invention provides an overrun relief port which, although it slightly lowers the overall efficiency of the unit, provides means for breaking the initial vacuum that tends to stall the motor on starting, and it provides that service, at a low cost, and with exceptional reliability. The loss in efficiency caused by the starting relief port, or ports, is minimized by locating the said port or ports at a point where the loss in efficiency on the compression upstroke is minimized. Small capacity air compressors of the rocking rod piston--wobble piston--type when driven by low powered A.C. motors of low starting torque, and having overrun intake ports, tend to stall. This calls for a larger motor which adds to the cost. Applicant devised the present system of unloading the compressor by providing a small constantly open passage between the inside and outside of the cylinder, which passage is located at a point in the cylinder wall at a short distance from the upper end of the compression stroke where the conflicting consideration of loss in efficiency of the compressor operation tends to be balanced by reduction in the initial cost and the operating expense of the motor. The outright gain is the certainty of going into operation when the motor circuit is closed.

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Sheboygan, WI, United States of America

Thomas R Hetzel