Silent Housing For Air Pumps And Compressors

Abstract

A silent housing for air pumps and compressors is of sound-deadening material and has an air inlet filter, a pair of air intake resonant valves tunable to an upper frequency of the pump or compressor, and a pair of outlet valves tuned to the same frequency as the intake valves and discharging in opposite directions into a common outlet channel for sound interference.

Description

The present invention relates to silent housings for air pumps and compressors.

In measuring and control techniques and in automation, the use of air as an energy carrier has become increasingly prevalent. Pneumatic pumps or air compressors are used to feed such pneumatic systems, and it is desirable that these operate silently.

Silent operation can be achieved by the provision of a central air supply network, but such a system is undesirable because it is fixed and involves complicated piping and high initial cost.

Accordingly, it is an object of the present invention to provide silent housings for air pumps and compressors, which will be of relatively small size.

Another object of the present invention is the provision of such housings that will permit a high rate of air delivery for a relatively small installation.

A further object of the present invention is the provision of such a housing which will be portable.

Finally, it is an object of the present invention to provide such a housing which will be relatively simple and inexpensive to manufacture, easy to assemble, install, operate, maintain and repair, and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawing, in which:

FIG. 1 is a somewhat schematic perspective view of a housing according to the present invention; and

FIG. 2 is a cross-sectional view, on an enlarged scale, of a tunable resonant valve for use in the housing of FIG. 1.

Referring now to the drawing in greater detail, and first to FIG. 1 thereof, there is shown a housing 1 for a pneumatic pump or compressor, made of a conventional sound-deadening material, and having an air inlet through a porous sound-absorbing air filter 2. Air from filter 2 then proceeds in parallel paths to a pair of resonantly tunable intake valves 3 and 4, which are both tuned to the same frequency which is an upper harmonic of the speed of the pump or compressor.

From the valves 3 and 4, the air proceeds to the pump or compressor (not shown) which is housed in the region 5 of the housing 1. From the outlet of the pump or compressor, the air then enters a pair of resonantly tunable outlet valves 6 and 7 which are both tuned to the same frequency as each other and the same frequency as valves 3 and 4. From the valves 6 and 7, the air continues to follow the paths shown by the arrows in FIG. 1, and enters opposite ends of a sound-interference air conduit 8. The oppositely moving streams of air in conduit 8 move at an angle of 180.degree. to each other and meet at the midpoint of the conduit 8 with a sound-deadening effect, and then leave the housing through outlet fitting 9 with a minimum of noise.

An individual resonantly tunable valve, such as 3, 4, 6 or 7, is shown in cross section in FIG. 2. As is there seen, each of these valves comprises a stem 10 which is externally screw-threaded and which has a slot 10a at one end for longitudinal adjustment by rotation with a tool, and an abutment shoulder 10b at the other end. Shoulder 10b bears against a coil compression spring 11 with an adjustable force that tunes the valve. Spring 11, in turn, bears against a valve member in the form of a ball 12. The valve body 13 screw-threadedly receives stem 10 and is provided with a valve chamber 13a within which the abutment shoulder 10b, the spring 11, and the ball 12 are disposed. Body 13 also has outlet orifices 13b for the escape of air from the open valve.

Stem 10 is sealed against valve body 13 by an annular sealing washer 14 at one end of chamber 13a; and at its other end, chamber 13a is closed by an inlet fitting 15 which provides a valve seat and which has an axial inlet opening 15a that is closed by the ball 12.

The opposite end of body 13 is covered by a cap 16 which is removably screw-threadedly secured thereto, selectively to expose or to cover the slot 10a.

In operation, with cap 16 removed, a tool is inserted in slot 10a to rotate the stem 10 to change the compression of the spring 11 so that the frequency of ball 12 on the seat provided by fitting 15 is such that the valve will be tuned to an upper harmonic of the speed of the pump or compressor. Air then enters casing 1 through filter 2 and proceeds to and through the valves 3 and 4 and to and through the pump or compressor and in parallel paths to the valves 6 and 7, whose outlets are opposed in conduit 8, and thence through the outlet 9 to the ambient atmosphere.

It will of course be understood that when air enters the resonant valves, the ball 12 is pushed from the seat provided by fitting 15 so that a through passage from inlet 15a to outlet 13b is provided. In the course of this motion, the ball loses a portion of its potential energy and spring 11 is compressed. By virtue of the inertia of the ball, the ball moves away from its seat until its potential energy is counteracted by the spring force, whereupon the ball stops and tends to move again toward its seat, this process being reversed and repeated until pressures acting on both sides of the ball become equal. Thus the effective cross section of the valve depends not only on the diameter of the inlet 15a, but also on the mass of ball 12 and the pressure in spring 11.

Although the present invention has been described and illustrated in connection with a preferred embodiment, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Claims

Having described my invention, I claim:

1. A silent housing for air pumps and compressors, comprising a sound-deadening air inlet filter, at least one inlet valve that receives air from the filter and that releases air to the pump or compressor in the housing, means to tune said at least one inlet valve to an upper harmonic of the speed of the pump or compressor, at least one outlet valve that receives air from the pump or compressor, means to tune the said at least one outlet valve to said upper harmonic, and means to discharge air from said at least one outlet valve to the exterior of the housing.

2. A housing as claimed in claim 1, there being a pair of said outlet valves in parallel, said discharge means comprising a channel to which air is discharged from said outlet valves in opposite directions from opposite ends of the channel, said channel having an outlet intermediate its ends.

3. A housing as claimed in claim 1, of a sound-deadening material.

4. A housing as claimed in claim 1, there being a pair of said inlet valves which receive air in parallel from said filter.

5. A housing as claimed in claim 1, each of said valves including a valve member for closing the valve and means yieldably urging the valve member toward closed position against the force of air entering the valve.

6. A housing as claimed in claim 1, each of said valves comprising a valve body, a valve seat at one end of the body, a valve member seated on the valve seat, a resilient element urging the valve member against the valve seat, a spindle screw-threadedly disposed in the valve body and bearing against said resilient element, and means to rotate said spindle to adjust the stress in said resilient element.