US1496543A - Compressor-unloading means - Google Patents

Description

June 3 1924.

Filed Oct. 29. 1921 H C JOHANSEN COMPRESSOR UNLOADING MEANS Chica Patented June 3, 1924.

UNITED STATES 1,496,543 PATENT orncs.

may O. JO, 0] GH'IOLGO, ILLINOIS, ASSIGNOB 'I'O SULLIVAN MACHINERY OOBJPOBA'IIOII', ADORPOMTION OF MASSACHUSETTS.

. oonnnssoniunmnnme mus.

Application October 39, 1931. Berti! I0. 511,380.

To all whom it may concern:

Be it known that I, Hannr O. Jonansmz, a citizen of the United States, residing at go, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Com ressor-Unloading Means, of which the fol owing is a full, clear, and exact specification.

My invention relates to compressor unloading means.

An object of my invention is to provide an improved com ressor unloading means, and more especia y an improved compressor unloading means of the auxilia type adapted tobe used with a compressor avmg an intake type unloader, and to avoid the compression of air which mi ht leak past" the intake unloader valve w en the compressor is turning over unloaded, from a partial vacuum to receiver pressure and -so the generation of excessive temperatures. Other objects and advantages ofmy invention will be apparent in the course of the following specification and appended claims.

In the accompanying drawings, I have shown for pur ease of illustration one embodiment whic my invention may assume in ractice.

these dra s,-

Fig. 1 is a side e evation of a com ressor provided with my improved on oading means.

2 is a detail view, partially in section, of the high ressure cylinder, showing the relationof e unloading means thereto.

Fig. 3 is a central longitudinal section through my improved unloadipgwgec msm.

Fig. 4 is a transverse section on the line 44 of 'F' 3.

This mec anism is an improvement u on the mechanism illustrated in my copen mg application for compressors, Serial No. 295,482, filed May 7, 1919.

Referri to the drawings in which I have shown the illustrative embodiment of my invention and particularl to Fig. 1, it W111 be noted that I have own a compressor of the angle compound type havin a horizontal low-p double acting cy inder 1, a high pressure double acting vertical cylinder 2, and drivi mechanisms for the pistons reciprocable an these cylinders whereby the two stages are operated from the single crank shaft 3. The intake to the low pressure cylinder 1 is through an inlet pipe 4 and is controlled by an automatically operated unloading means 5, such as is in common use on compressors, to unload the compressor by closing the intake thereto when the pressure in the receiver or pressure discharge line exceeds a predetermined desired amount. The partially compressed air or other fluid passes from the low pressure cylinder through intercooler 6 to the hi h ressure cylinder 2 and thence by way 0 a ischarge i e 7 to the point of use or to a receiver. en the pressure in the receiver, or other point to which the pipe 7 is connected, rises above the predetermined desired pressure named, the unloading means 5 is operated by automatic means which are so well known as not to need description at this point and the intake to the compressor is thereby closed and hence the compressor, if there is no leakage, no lon er operates to com ress air drawn in ihrolg the line 4 and to discharge it to the In practice, it is possible that the intake controllin mechanism may not completely close all t e connection between the pi 4 and the low pressure cylinder 1 or that t are 'may be other leaka perhaps through the stufling boxes, an under those circumstances the continued reciprocations of the piston in the low pressure cylinder may draw in a reduced char of air into the low pressure cylinder w ich is insufl'icient to fil it at atmos heric pressure.- Therefore, at the end of the suction strokes the cylinder may have in it air at a relatively low pressure which air will be com ressed and forced lnto the intercooler. 's air which leaks by the intake unloading mechanism and is passed into the intercooler is not materially compressed in the low pressure cylinder by reason of the fact that the intercooler pressure is pum d down to a artial vacuum by the hi pressure cyllnder. Therefore, in the high pressure cylinder, since the same condition prevails as in the low pressure cylinder, i. e. that at the end of the suction stroke of the high pressure piston there is a artial vacuum in the hi h pressure cylin er, there occurs upon t e compression strokes of the piston a compzeession of a charge of air from perhaps t e pounds or more absolute up to thepressureinthedisehargelineLsa 100 pounds gage or more. As a result 0 the number of compressions during this operation, a very considerable amount of heat is generated which at times may be suflicient to explode mixtures of gas and air formed in the h ressure cylinder from va mation of e ubricating oil, or, if this does not occur, to carbonize the lubricant in the pressure cylinder and so reduce the labricat sficienc To avoid dificulty of this kin and aim ar trouble, I have mounted upon the high pressure cylinder 2 my improved unloading mechanism which avoids the compression of fluid up to dis char line pressure and instead rnnts the sage of fluid from the big prescylin er to the atmosphere at ressures not greatly exceeding atmosp eric pressure.

My improved unloading mechanism is designated 8 and comprises a casmg ma e u of three parts,-two and sections 9 an 10 and a central section 11. The end sections are bored to provide coaxial cylinders 12 and 13 and in their normal tion these cylinders lie with their axes h iizontal. The central section is rovided with a slightly enlarged bore an at its op 'te ends has valve seating surfaces 14 an 15. Reciprocable in the c linders 12 and 13 are pistons 16 and 17 w ich are closed at their ad'acent ends and provided with rims 18 an 19 respectively adapted to seat u n the valve seating surfaces 14 and I5. hcse istons, as illustrated, have 0 rear end, t this is not requisite and t e rear ends thereof may be closed if desired. Between the adjacent closed ends of the pistons 15 and 16 is disposed a spring 20 which is of slightly greater length than the distance between the valve seatin surfaces 14 and 15. Each of the cylin era is provided with an enlarged annular counterore at its end adjacent the central section 11, these counterbores being designated respectively 22 and 23. The rims 18 and ltv are adapted to cooperate with the remote ends of these counterbores to limit the unseating movements of the valve pistons 15 and 16. The rear end of each cylinder is connected to the counterbore of the other, the rear end of cylinder 12 bein connected by s assage 24 to the counter re of the cylin er 13, while the rear end of the cylinder 13 is connected to the counterbore 22 of the c linder 12 b a passage 25. Pipes 26 and i connect t c Passages 24 and 25 to the op osite ends 0 the cylinder 2 at points so ocated that the connections will not be wholly overrun by the piston. The bore of the central sectionof this unloadi means is connected by "a port 28 control] by a spring pressed end seating valve 29 with an atmospheric vent 80.

The mode of operation of this mechanism will be readily apparent. When the compressor is operating loaded, the pressure in the lines 26 and 27 will vary between intercooler pressure 7 and compressor pressure. will remain constantly seated. When the intake to the low pressure cylinder is closed, the low pressure cylinder will no longer supply any appreciable amount of air to the intercoolcr and the intercoole'r ressure will be rapidly pum down by t e high pressure cylin er. ere will then promptcome a time when the pressure on one of t e suction strokes of the piston will fall low enou to cause the air in the chamber between e valves to open the valve whose rear end is connected to the end of the cylinder in which suction is taking place before the pressure on the other side 0 the dischar As a result the valves 15 and piston gets high enough to keep the valve closed. This .will result in the dischar through port 28 of the premure in the h' ressure cylinder as soon as it reaches a 'ttle above awh eric pressure, and of course at such a tem rature that no injurious result is possib e. The mechanism will tlfiareafier sct(as a relief means), connect! t swam i. e. compressing sides of t e piston to atmosphere whenever the pressure is until the cyhnder 1S reloaded. will evident that as one valve seats the spring, which is just a little longer than the distance between the two valves when seated, will cushion its seating and will aid in the unseating of the valve which is about to open. This arran ment produces a more certain action of t e valves and practically eliminates all slapin of the valves upon their seats and r age resulting from that cause.

Whi e I have in this application specifically described one form which m mvention may assume in practice, it w' be understoo that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without delparting from its spirit or the scope of t e appended claims.

What I claim as new and dmire to secure by Letters Patent is:

1. An unloading mechanism for a compressor cylinder comprising a casing, a plurality of valves therein, 'a connection with the atmosphere, tpassages leading from each end of the cylin er to said casi and having their communication with e atmospheric connections controlled by said valves, each of said valves being governed as to o the pressure conditions in that one of and connections which it does not control and s ring .meanscooperating with said valves an tending to unseat them when th are seated.

2. An unloading mechanism for a compnessor cylinder comprising a multipart casing consisting of spaced cylinder sections connected by a central section, cylinder bores in said cylinder sections, a central bore in said central section in alinement with said cylinder bores and surrounded by seat areas, counterbores in said cylinder sections adjacent said central sections, pistonsdis sed in said cylinders and having enlarge heads reciprocable in said counterbores and adapted to cooperate with said seat areas, a spring disposed in said central bore and of a length when uncompressed greater than the distance between said pistons when the latter are seated, and connections each connecting one end of said comressor cylinder with one of said counterres an the opposite end of the opposite cylinder.

3. An unloading mechanism for a compressor cylinder comprising a casing, a plurality of oppositely disposed valves therein, a connection with the atmos here between said valves, connections leading to the o?- posite ends of the cylinder controlled y said valves, a. ring between said valves of a length slig tly eater than the distance between said va ves when they are in their most proximate positions to each other, and means for causin said valves to alternately act as relief va ves.

In testimony whereof I aflix m si ature.

HABRY' C. J 0 EN.

Images