US2580341A - Fluid compressor and cooling apparatus therefor - Google Patents

Description

1 B. s. AIKMAN 2,580,341

FLUID COMPRESSOR AND COOLING APPARATUS THEREFOR Filed Sept. 29, 1948 N V EN TOR. e URTON s. A K MAN mg, AT TOR NEY Patented Dec. 25, 1951 UNITED STATES ATENT OFFICE FLUID COMPRESSOR- AND COOLING APPARATUS THEREFOR Application September 29, 1948, Serial No. 51,817

4 Claims. (0]. 230-208) This invention relates to air compressors and more particularly to means for controlling the temperature thereof.

In the operation of air compressors the heat developed by the compression of air tends to cause carbonization of any oil which may enter the discharge valve chamber resulting in formation of' a carbon deposit on the walls of said chamber. This reduces dissipation of heat resulting in an even higher temperature in the chamber than otherwise would occur which tends to warp and crack the discharge valve and associated elements and render them at least inefiicient in operation if not substantially unfit for service. Moreover heat from the discharge valve chamber is transmitted to other parts of the cylinder head and the adjacent portion of the cylinder wall or walls which tends to burn oil and create carbon deposits thereon.

The principal object of the invention is therefore the provision of improved means for so controlling or limiting the temperature of the air in the discharge valve chamber of a compressor as to avoid the above difiiculties.

Other objects and advantages will become apparent from the following more detailed description of the invention.

In the accompanying drawing, the single figure is a schematic view of a multiple stage air compressor embodying a preferred form of the invention.

As shown in the drawing, the compressor comprises a cylinder portion l containing low and high pressure pistons 2 and 3, respectively, and a pressure head 4 secured to the portion I over the pressure ends of the pistons and cooperating therewith to define pressure chambers 5 and 6,

"respectively. The pistons 2 and 3 are adapted to be operated in unison by rod connections with a common crank shaft (not shown) in the usual manner. Numeral l designates the piston end of the operating rod for the low pressure piston 2. 8"de'signates an inlet valveand 9 designates a discharge valve for the low pressure chamber 5, while lli and II designate inlet and discharge valves, respectively, for the high pressure chamvalve chamber [3 is open to the inlet end of an intercooler or heat radiator M the outlet end of which is open to a pipe l5 leading to a chamber i6, the high pressure inlet valve l0 controlling inlet of air from chamber It to the high pressure chamber 6. The high pressure discharge valve II, contained in a discharge valve chamber l'l, controls communication between the high pressure chamber 6 and the chamber ll, the latter chamber being open through a pipe l8 to one end of a storage reservoir 19. The opposite end of the reservoir [9 is open through an aftercooler or heat radiator 20 to one end of another storage reservoir 2i, the opposite end of which is connected a pipe 22 adapted to convey the compressed air to a point of use.

The structure so far described is conventional, it being desired to point out, however, that the intercooler I4 is provided for dissipating heat from the air compressed thereinto by operation of the low pressure piston 2 so that relatively cool air will be provided for compression by the high pressure piston 3 into the reservoir l9, aftercooler 29 and reservoir 2 I, said reservoirs in effect constituting a part of heat radiating means including the aftercooler 20, so that relatively cool air will be delivered to the pipe 22 for use.

According to the invention, an air circulating piston 23 of smaller diameter than and associated with the low pressure air compressing piston 2 projects centrally from the pressure head of piston 2 through the low pressure chamber 5 into a bore in the pressure head 4 wherein it cooperates with said head to form a chamber 24. An inlet valve 25 is provided for controlling flow of fluid under pressure from a chamber 26 to the chamber 24, while a discharge valve 21 is arranged to control discharge of air from chamber 26 to the discharge valve chamber l3. The chamber 25 is open to a passage 28 in the compressor head 2 which passage forms a fluid flow connection between the outlet end of the intercooler 14 and pipe is leading to the high pressure chamber 6.

In operation, it will be seen that the air circulating piston 23 will reciprocate with the low pressure air compressing piston 2 and upon the intake stroke of the latter piston will draw relatively cool air from the outlet end of the intercooler l4 past the inlet valve 25 into chamber 24, while upon the air compressing stroke of piston 2, the piston 23 will discharge the relatively cool air from chamber 24 past discharge valve 21 into the discharge valve chamber I3 wherein it will mix with the impulse of relatively hot turbulent compressed air being delivered past the discharge valve 9 by the low pressure air compressing piston therefrom to said discharge valve chamber, and

hence substantially no increase in the temperature of the delivered air andth'e size or displace'- ment of the circulating piston 23 is so related to the displacement of the air compressing piston 2 that the desired cooling of the hot compressed air delivered to said discharge valve chamber results for the purpose above described.

Similarly, a circulating piston 33 of smaller diameter than the high pressure air compressing piston 3 projects from the pressure face thereof into a bore into the pressure head 4 with which it cooperates to form a chamber 29 communicating past an inlet valve 38 and through a pipe 3| with pipe 22 at the outlet end of the high pressure heat radiating means including reservoirs IE! and 2| and the aftercooler pipe 2 l, and communicating past a discharge valve 32 with the high pressure discharge valve chamber ll. As will be seen, the

'circulating piston 28 will reciprocate with the high pressure air piston 3 to draw past the inlet valve 30 relatively cool air from the pipe 22 upon the intake stroke of the latter piston and to discharge this air past discharge valve 32 and through the discharge valve chamber l7 upon the air compressing stroke of the latter piston, whereby the temperature of the relatively hot air delivered past the discharge valve H by said latter piston will be reduced by the cool air delivered by piston 28 to a degree to prevent carbonization of any entrained oil and to also prevent damage to said discharge valve.

By immediately reducing the temperature of the air delivered by the low and high pressure air com ressin pistons 2 and 3 past the discharge valves and ii, respectively, to a safe degree as above described, undue heating of the walls of the discharge valve chambers l3 and H and thereby oi the'pressure head I and adjacent portions of the cylinder portion I, as well as of said pistons will also result.

7 Having now described my invention, what I claim as new and desire to secure by Letters Patent, is:

1. Means for reducing the temperature of ai "in the discharge valve chamber of an air com pressor comprising in combination, a discharge valve in said chamber, an air compressing piston ior compressingair past said valve into said chamber, air inlet means for said piston, another air compressing piston having an intake and, also having a discharge connection with said chamber, intake and discharge valves in, respectively, said intake and discharge connections, and heat radiating means connecting said intake to said chamber.

' ing means.

2. In an air compressor having inlet and discharge valve chambers, inlet and discharge valves, respectively, in said chambers,'a piston for drawing air past said inlet valve and discharging it past said discharge valve into said discharge valve chamber, a second piston secured to and projecting from the pressure face of the first-named piston, and an air circulating circuit including said second piston having inlet and discharge con nections with said discharge valve chamber and also including heat radiating means.

3. In an air compressor having inlet and discharge valve chambers, inlet and discharge valves, respectively, in said chambers, a piston for drawing air past said inlet valve and discharging it past said discharge valve into said discharge valve chamber, said compressor having second inlet and discharge valve chambers and inlet and discharge valves, respectively, mounted therein, a second piston secured to and projecting from the pressure face of the first-named piston for drawing air past said second inlet valve and'diScharging it past said second discharge valve, means opening the two discharge valve chambers to each other, and means including heat dissipating means opening the first-named discharge valve chamber to the second-named inlet valvechamber.

fl. Means for reducing the temperature of the air delivered by the lowand high pressure pistons of a two stage air compressor comprising in combination with said pistons, air inlet means for said low pressure piston, means including low pressure heat radiating means for connecting the discharge of said low pressure piston to the intake for said high pressure piston, means including high pressure heat radiating means for conveying fluid under pressure away from said high pressure piston, two air circulating pistons of smaller diameter than and integral, respectively, with each of said low and high pressure pistons, mean including a discharge valve connecting the discharge of each of said circulatin" pistons to respectively the discharge of said low and high pressure pistons, and means including inlet valves connecting the inlet to the air circulating pistons for'said low and high pistons to, respectively, the outlets of said low and high pressure heat radiat- BURTON S. AIKMAN, REFERENCES CITED The following references are of record in the file of this patent: V

UNITED STATES PATENTS

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