US1638212A - Automatic air-compressor unit - Google Patents

Description

Aug. 9, 1927,

- 1,638,212 J. RAYFIELD AUTOMATIC AIR CCSMPRESSOR UNIT Filed ADIil 30, 1925 2 Sheets-Sheet l ill" #14 0 v2 {EEK Fred J R fzezd F. J. RAYFIELD AUTOMATIC AIR COMPRESSOR UNIT 2 Shoots-Sheet 2 Aug. 9, 127.

Filed April 30, 1925 I I i 26 E o w I I? 2 C v v E 1:!

.& 1

I Fred J: Rayfild Patented Aug. 9, 1927.

UNITED STATES 1,638,212 PATENT OFFICE.

FRED JZ' RAYFIELD, OF CHICAGO, ILLINOIS. ASSIGNOR, TO CHAMPION PNEUMATIC MACHINERY 00., A CORPORATION OF ILLINOIS.

AUTOMATIC AIR-ooMrREsson' UNIT. i

Application filedApril 30, 1925. .Serial No. 26,855.

This invention relates to the automatic control of storage type air compressors adapted to maintain the air pressure within .apredetermined range.

It is an object ofthis invention to provide an improved air compressor system which is fully automatic in operation 'although using a water cooled compressor. Heretofore automatically controlled air compressor units have been limited to the smaller sizes due to the necessity of the use of air cooled compressors because of difliculti es in the practical control of the cooling water system of the larger compressors. This invention provides means for automatically controlling the water circulation in step with the automatic control of the compressor proper, and includes in this control an unloading device for the compressor that will allow the starting thereof without initial loadeven though the main air reservoir is under considerable pressure.

It is another object of this invention to provide a cooling water control, for use in connection with an automatic air compressor system,:wherein the water control will be timed to'stop the water; circulation slightly after stoppageof. the air compressor and to start the water circulation after-the air compressor starts again. 5, i

It is also an ob 'ect of this invention to provide a settling chamber intermediate the air compressor and'receiver and to provide means venting thischamber upon stoppage of the compressor; the venting of the chamber serving to unload the compressor for restarting and to shut ofl the cooling water circulation for the compressor. when the pressure in the chamber drops below a predetermined point. 7 7

It. is a further object Let this invention to provide an improved and simplified fully automatic control for an air compressing system adapted to be easily and economically manufactured, installed, and maintained.

Other and further important objects of this invention will be apparent from the disclosures in the specification and drawings.

The invention (in a preferred form) is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a side elevation of an automatic air compressing apparatus embodying thefeatures of this invention.

7 parts in section.

I Figure 2 is a top plan view thereof ona.

reduced scale.

Figure 3 is a-fragmentary diagrammatic elevation of the water and air circuits with Figure 4 is'la vertical central section through the automatic control.

Figure 5 is a section on the line 55 of Figure 4. i

Asshown on the drawings: The self containedand automatically .controlled air compressor outfit shown comprises a water jacketed air compressor havinga belt drive 11 from a motor 12, an idler pulley 13 being provided to maintain proper belt tension. 7 The air compressor delivers air to a small settling tank 14 through the-pipe 15 and thence to the main air reservoir 16 throughthe pipe 17 which contains a check valve 18. to prevent back flow. A

pipe 19 from the air reservoir connects to an automatlc electric controller 20 which controls the operation of the motor. The whole apparatus mentioned is compactly mounted on a base 21 as .shown in Figure 2. sothat the ,outfitis a unit requiring only water and electric connection from external sources.

The. specific form of automatic electric controller 20 per se does not enter into this invention except as an element of the general combination. It is, therefore, necessary only to briefly describe the construction and operation of the particular form chosen for illustration. This controller is provided with an operating lever 22 pivoted. at '23. One'end of the lever is connected to and is adapted to open and close a current controller switch 24, and. the other end is provided with a V- shaped projection or cam 25 against which a roller 26 in aspring. urged lever 27 is held. .Theroller 26 is adapted. to be raised and lowered by the air pressure in the reservoir 16 by means of a diaphragm comprising one wall of a pressure chamber 28 connected to the reservoir by the pipe 19. As the pressure in the main reservoir increases the roller travels up the lower incline of the cam 25 until it passes the peak thereof, at which time the spring pressure to which the lever 27 is subjected causes the roller to advance on the upper incline of'the cam thus depressing the cam end of the lever 22. By this means the circuit supplying current to the motor is broken and the compressor stops.

As the pressure decreases in the reservoir the roller descends the upper-incline until it passes the peak of the cam and then it acts to lift the end of the lever 22 and close the circuit to start the motor. A spring 29 is provided which is adjustable to control the pressure in the reservoir. This switch mechanism is a snap-over switch in that it is suddenly opened and closed as the roller passes over the peak of the cam 25.

A bleeder pipe 30 is connected between the pipe 17 below the check valve and a vent valve 31 operated by the motor controller 20. This bleeder pipe serves to relieve the pressure within the settling chamber and to therefore unload the compressor upon stoppage thereof so that restarting will be without appreciable initial load. Such a mode of operation is particularly necessary with A.

G. motors because of the difliculty of starting such motors under load. Thevent valve 31 comprises a housing 32 secured to the side of the controller housing'andprovided with an inlet- 83 connected to the bleeder pipe and-an outlet 84. Between the inlet and outlet is a vertical passage having a normally closed ball valve 35 therein. To open the vent when the motor stops a plunger rod 36 is mounted verticall in the casin C and adapted to be depressed to force the ball off its seat. To accomplish this the rod 36 is positionedtobe engaged by a pin 37 projecting from' the lever 22 near the cam 25. This pin engages the rod 36 when the lever 22 is depressed to open the motor circuit.

The water supply for the cooling jacket of the compressor is brought thereto by the pipe 38 and discharges therefrom through the pipe 39 having a control valve 40 mounted therein. The valve 40 comprises a spring loaded disc 41 normally'closing the outlet passage, and an aligned piston 42 and plunger 48 adapted to force the disc 41 off its seat when air pressure is conducted behind the piston by the pipe 44 leading to the settling tank.

The operation of this air compressor outfit has been partly described in connection with the automatic controller whereby shutting down the motor releases the pressure within the small settling chamber. The complete release of pressure is somewhat delayed due to' the small size of the bleeder pipe and therefore the water valve will have a lag with respect to the action of the controller, the valve 40 not closing to stop the water circulation until the pressure drops considerably. The continued water circulation prevents overheating due to the heat stored up in the cylinders and pistons of the compressor which in the case of simultaneous stoppage of both the compressor and water circulation might cause overheating of the water tapped in the water jackets. Similarly thevalve' 40 is not opened upon starting the motor until the pressure in thesettling tank is built up again so that the compessor has a chance to warm up its jacket water and to approximate a favorable temperature for lubrication and piston sealing before the water circulation starts again. This'control of the water circulation in accordance with the operation of the compressor brings the'larger sizes of compressors, necessarily water cooled, within the bounds of. full automatic control, andthe slight lag in the water :con-

trol approximates this feature of manual control automatically. V

I am aware that numerous details of construction may be varied through a wide range without departing from the principles of in said settling chamber and means respon-- sive to the pressure in said settling chamber adapted to shut off the cooling Water circu-- lation for said compressor after the release of the pressure in said settling chamber.

In testimony whereof I have hereunto subscribed by name.

FRED J. RAYFI'ELD.

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