Unloading device

Application filed May 15, 1829. Serial No. 363,214.

This invention relates to improvements in unloading devices for air or gas compressors, and more particularly to a novel unloading device arranged in the discharge pipe of the 6 compressor and controlled by pressure in the compressor cylinder for automatically unloading the discharge pipe between the compressor and check valve whenever the compressor comes to a stop. Such unloading de10 vice facilitates the starting of the compressor against the load, thereby preventing the burning of the motor and transmission belt.

I have heretofore proposed a combination check valve and unloader operating in the 15 discharge pipe of the compressor, and actuated by the variations in the flow of air or gas through the device', and the primary object of the present invention is to provide an unloading device which is controlled, by the 20 pressure in the compressor cylinder in starting, and by reduction of pressure in the unloading device back to the compressor cylinder after the compressor comes to a stop for unloading the discharge pipe.

Another important object of my invention when used on small compressors, is to automatically drain the water and oil waste from the discharge line each time the compressor ceases its compressing operation. I am aware 39 that unloaders of the “bleeder” type are in general use, but such unloaders have given considerable trouble. The pressure switch bleeder valve is the type most generally in use on automatic motor driven compressor 35 units, and if the current fails or is switched off while the installation is in operation, the pressure switch remains closed, due to the fact that the pressure has not been built up to the cut-out point. Consequently, the to bleeder valve remains closed and the compressor is not unloaded. Subsequently, when the current is resumed, under such conditions, the installation- will start against full tank pressure, which causes blowing of fuses, burn45 ing or j umping of belts, and sometimes a more expensive occurrence, a burned out motor.

My invention eliminates the possibilities of the above mentioned troubles, since the operation of the unloading device is independent of electrical means, and wholly dependent on the movement of the compressor piston for opening and closing the unloader.

Another object is to furnish an unloading device designed to unload the discharge pipe so rapidly as to cause the ordinary check ₆₅valve between the receiver and the compressor to be instantaneously forced to its seat. Air check valves of the dash pot type, often fail to seat, due to sticking caused by oil waste or carbon deposits, which sticking results in 60 many other troubles.

Another object is to provide an automatic unloading device of durable and rugged construction, simple and cheap to manufacture, non-sticking, non-dogging, and positive in 65 action.

It may be stated further that most unloading devices in use today require adjusting means to have the device accord with the compressor for which it is used. As inexperi- 70 enced operators do not know how to properly adjust such devices, or the adjusting means themselves become loose, and get out of order, this results in the device becoming clogged, therefore, it is a further object of this inven- 75 tion to provide an unloading valve which is fitted to the compressor and regulated automatically by the flow of air through the same, and which is not sensitive to clogging, due to the fact that it has a large bleeding port. so

With the foregoing objects outlined and with other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the .accom- 85 panying drawings, and more particularly pointed out in the appended claims.

Referring to the drawings,

Fig. 1 is a side elevation of a compressor and receiver, shown combined with one form 90 of my improved unloader.

Fig. 2 is an enlarged vertical sectional view partly in elevation, of a portion of the unloading device.

Fig. 3 is a horizontal sectional view, on the 95 line 3—3 of Fig. 2. . .

Fig. 4 is a similar view of a modification.

Fig. 5 is a longitudinal sectional view of a special check valve forming part of the apparatus shown in Fig. 1< ¹⁰⁸

1,817,088

In the drawings, 6 designates the cylinder of an air or gas compressor 7, which is driven by a motor 8, through the medium of a belt 9. The fluid compressed by the piston (not _e shoivn) of the compressor, is forced through the discharge pipe 10, into the receiver 11, and this discharge line is preferably provided with a manually controlled valve 12 and a check valve 13, the latter preventing 1q any return of the compressed air or gas from the receiver to the compressor cylinder.

The parts 6 to 13 inclusive may be of conventional construction, and the present improvements includes a T 14 which may be 15 connected as shown in Fig. 1, to an unloading chamber 15, the lower end of which is joined to my improved valve 16. This valve in turn has its lower end in communication with the upper end of the cylinder 6, by means to of a narrow pipe 17.

As best shown in Figs. 2 and 3, the valve 16 is provided with an externally threaded axially disposed nipple 18 which may be screwed into the lower end of the unloading 25 chamber 15, as shown in Figs. 1 and 2, or may be screwed directly into the T 14, as indicated at 19 in Fig. 4. A port 20 in the valve casing communicates with a chamber 21 of the casing, in which a valve 22 oper30 ates. While this valve may be of any suitable construction, it is preferably of the needle type, and its conical end 23 cooperates with an annular valve seat 24 provided at one end of the port 20. This valve has a disk 35 25 at one end which is pressed by a spring 26 against a flexible diaphragm 27 that is preferably clamped in position against one end of the casing by means of a threaded cap 28 which has an internally threaded port 40 into which one end of the pipe 17 is screwed.

The chamber 21 of the valve casing is in constant communication with the atmosphere by means of a pipe 29. - As shown in Fig. 5, tne. pipe 17 is connected to the compressor 45 cylinder by means of a special check valve 30.

This check valve is constructed to bleed in opposite directions. Its valve housing 37 has two valve seats 38 and 39 which cooper50 ate with a ball 40. In this form of the invention, each valve seat has a bleed groove 41, 42. Consequently, with this form of check valve, while the compressor is forcing air through the pipe 17 into the chamber 36, 55 the passage of air will be delayed due to the bleed groove 41. On the other hand, during unloading, the groove 42 will restrict the passage of air from the chamber 36, and somewhat retard the unloading.

As shown in Fig. 4, the pipe 17 is connected to the compressor cylinder by means of another form of check valve 30α which includes a tubular housing 31 that is internally threaded for connection with the pipe c.j 17. This housing has an annular valve seat that cooperates with a ball· 33 which is forced towards the seat by a coiled spring 34. A bleed groove 35 extends along the bore of the housing from the valve seat toward the interior of the cylinder 6 for the purpose of 70 delaying the return of the pressure fluid from the chamber 26 of the unloader valve to the compressor cylinder.

In operation, it will be understood that the compressor 6 will force the air or gas through 75 the discharge pipe 10, into the air receiver 11. The pressure fluid will not alone be forced through the pipe 10, but it will immediately be built up in the chamber 36 to close the valve 22 to prevent any bleeding of 80 the air to atmosphere through the pipe 29, while the compressor is in action. While the compressor is in action, especially with small compressors, water and waste oil will gather in the chamber 15, and my improved mecha- ⁸⁵nism functions not alone to unload the compressor but to discharge such water and oil waste.

When the pressure in the receiver 11 reaches a predetermined degree, the motor 8 90 is automatically stopped by the usual cut-out means (not shown). Immediately when this occurs, the unloader comes into operation, and the check valve 13 is instantly forced to its seat to iprevent any return of pressure 95 fluid from the chamber 11 to the cylinder 6. As the compressor comes to a halt, the pressure in the cylinder 6 automatically lowers and consequently, the spring 26 forces the valve 22 away from its seat, so that pressure 10® fluid in the conduit 10 and chamber 15 blows any water or oil waste out through the pipe 29 to atmosphere, and at the same time, it relieves the system at the entrance side of the check valve 13 of pressure fluid. 105

As shown in Fig. 5, the pressure fluid in passing from the chamber 36 to the cylinder 6, will pass through the bleed groove 42, and thus the releasing of the oil from the chamber 36 will be retarded to the desired degree Π®

On small compressor units, it is important to have what is termed an unloading chamber or copier, and trap. This chamber traps much of the waste water and oil, it cushions the pulsations on the check valve 13, it cools 115 the oil somewhat, and acts as an unloading chamber in that the compressor must turn over several times before building up much of a pressure. In draining oil from this chamber, it has always been necessary to do 120 so by opening a cock by hand. In my improvements, this is done automatically each time the compressor comes to a stop. When the compressor comes to a stop, the valve 22 is unseated, and the fluid in the chamber 15 125 is forced out through the pipe 29. After the fluid has been expelled, the air in the discharge line will also be released, and the system unloaded, cleaned and ready to be started. When the unloading chamber 15 is used, the icc

1,817,698 valve 22 will close on the first two or three duit between the unloader valve means and revolutions of the compressor, due to the fact the cylinder. . . .

that there is too much air space to be filled, 5. An appaartus as claimed in claim 2, mand very little pressure being produced on eluding a check valve interposed in said conthe side of the diaphragm 27, next to the duit between the unloader valve means and chamber 21 - cyhnder, and functioning to allow the

My unloading valve indicated in its en- , gradual flow of pressure fluid from the valve tirety by 16, made in one size, will operate ' means toward the cylinder.. successfully on several sizes of compressors, ^β »= plm but after a certain size compressor, the unloading valve should be a size larger in proportion to the next sizes of compressors it is to be used on. .

My unloader is simple, durable and of rugged construction. It is cheap to manufacture, dependable, positive in operation, comprises only a few moving parts, and can be easily assembled, even by an unskilled person. No adjustments are necessary with the 20 same. There is no sticking, and no clogging.

Furthermore, when it includes the chamber 15, the latter forms an automatic waste eliminator. . ,

The terms and expressions employed herein are used as terms of description, and not of limitation, and there is no intention in the use of such terms and expressions, of excluding anv equivalents of the features shown and described, or portions thereof, but it is recognized that various structural modifications are possible within the scope of the invention claimed.