US1819691A

US1819691A - Air compressor

Info

Publication number: US1819691A
Application number: US450390A
Authority: US
Inventors: Austin J Rix
Original assignee: Individual
Current assignee: Individual
Priority date: 1930-05-07
Filing date: 1930-05-07
Publication date: 1931-08-18
Anticipated expiration: 1948-08-18

Description

Aug. 18, 1931. A. J. RIX 1,819,691

AIR COMPRESSOR Filed May 7, 1930 2 Shets-Sheet l INVENTOR.

BY 2 1 A TTORNEYS.

Aug. 18, 1931. A. JVRIX 1,819,691

1 AIR COMPRESSOR Filed May 7, 1930 2 Sheets-Sheet 2 F a u. 3-- -L|L -u.L'

1/ INVENTOR.

i l I BY 1 mml WW ATTORNEYS. 9

Patented Aug. 18, 1931 UNITED STATES AUsTINa IX, or sAN FRANOiSCO, CALIFORNIA AIR comrnnssoa App1ication filed May 7 1930. Serial N; 450,390.

This invention relates to-air compressors and especially to a direct connectedmotor driven air compressor with mechanically actuated inlet and discharge valves.

E l Vhen the automatic duo plate air valves were first introduced on the vertically socalled high speed air compressors the speeds ranged from 400 to 500 R. P. M. and the lift of the valves were of sufficient height to pro- .10 vide the same area as the port openings in the valve seats so as to permit flow of air in and out of the cylinders without undue velocity or resistance. As the air compressor industry progressed the main trend has been towards '1 higher speeds and lighter weights. In order to obtain these speeds lighter and stronger reciprocating parts were necessary, Automotive practice was followed in designing the reciprocating parts with the result that high- 2 er speeds were obtained and construction generally improved but the valve mechanism was neglected. This resulted in valve breakage developed by rapidmovement of the concentric valve plates and in order to overcome '3 this trouble the liftof the valves were materially reduced and in some instances "cut in one-half, thereby reducing the lift area and causing air passage restriction. This of course resulted in loss in eificiency caused by 0 high cylinder pressures and temperatures and it also caused excess carbon deposits from the lubricating oils, increased horsepower consumption and the use of larger radiators for cooling purposes. It might also be stated that with duo plate types of valves there are large .45 ly800 R. P. M., hence if a gas engine or the like is direct connected to the compressor all the power of the engine is not available asthe majority of engines are designed to operate at speeds of 1200 to 1500 R. P. M. and 0 where electric motors are direct connected to the compressor it is necessary to employa 900 R. P. M. motor which is costly and heavy as stock motors operate around 1750 R. P. M. The object of the present inventionis to generally improve and simplify the con- 5 struction and operation of air compressors and particularly that type which is adapted to bezdirect connected to a source of motive power such as an engine or motor; to provide a compressor capable of eiiicient opera- 5 tion at engine or motor speeds, for instance, 12003. P. M. or more; to provide acompressor in which the clearance volume between the top of the piston and the head of the valve mechanism carried thereby may be greatly reduced; to provide a compressor in i which the valves are mechanically actuated;

to provide a compressor in which valves of large area and lift may be employed; to provide a compressor which is adapted for direct connection with internal combustion engines or the like and in fact adapted to be built as an integral part thereof; to provide a direct connected compressor in which the valves are adapted to be actuated by the cam shaft of the internal combustion engine; and further, to provide acompressor in whichthe inlet valve is adapted to be held in an open position by an unloader mechanism. Further objects will hereinafter appear.

H The invention is shown by Way of illustration in the accompanying drawings, in Wh1chv Fig. 1 1s a side elevation of a dlrect connected engine and air compressor, said side elevation being partially broken away to show partsv ofthe mechanism insection,

Fig. 2. is a vertical cross section of one of the air compressing cylinders, and v Fig. 3 is an enlarged cross section of the air compressor head showing the inlet valve and its actuating mechanism.

Referring to the drawings in detail and particularly Fig. 1, A indicates the cylinders of an internal combustion engine of the fourcycle type, B the crank shaft, C the cam shaft, which in this instance is driven from the crank shaft by :gears 2 and 3 in the usual manner; the speed ratio between the crank shaft and camshaft being two to one. The

crank case generally indicated at D which supports the cylinders A and the crank shaft B is, in this instance, extended to support a pair of air compressor cylinders generally indicated at E and F. Each cylinder is provided with a piston such as shown at 5 and as the crank shaft B is extended to provide two additional cranks such as shown at 6 and 7 the pistons 5 will be connected through rods 8 with the respective cranks and as such will move in unison with the pistons in the cylinders indicated at A. The cylinders E and F are identical in construction. They are both provided with inlet and discharge valves such as indicated at 9 and 10, respectively, these valves being mechanically operated from an extension of the cam shaft C hereinafter to be described.

The valves employed are poppet valves such as used in automotive practice, the inlet valve opening inwardly in the usual manner and being operated by a rocker arm 9a of the usual type as shown in Fig. 3. The discharge valve on the other hand sits on top of the cylinder and opens upwardly and a slightly modified form of rocker arm is accordingly required as indicated at 1064 in Fig. 2, this type of rocker arm permitting lifting of the valve while the other type of rocker arm indicated at 9a causes depression or inward movement of the valve. Both valves are operated by pusher rods such as shown at 11 and these are in turn actuated by the extended cam shaft C, the extension of the cam shaft being identical to any ordinary cam shaft with the exception that double lobe cams are employed as shown at 12 and 13, see Fig. 2. This is due to the fact that the cam shaft operates at a' one to two ratio due to the four-cycle motor employed. hence requiring two lobes for the actuation of the inlet and discharge valves on the compressor cylinders as the valves must be opened and closed once during each revolution of the crank shaft, or in other words, in a manner similar to a twocycle operation.

The discharge ValXQ 10 is, in this instance, held against its seat by means of a helical spring 15 and it is also held against its seat by air under pressure which is equal to receiver pressure. A check valve 16 of any suitable construction is interposed between the receiver and the discharge valve but as this is at a point remote from the valve 10 there will be an intermediate pocket of air between the check valve 16 and the valve 10 under a pressure substantially the same as that in the receiver. If an ordinary valve stem was employed there might be considerable leakage, hence a small piston 17 is applied to the upper end of the valve stem. The piston is guided in a bushed cylinder 18 and piston rings are employed as shown at 19. Vents 20 are formed between the lower end of the cylinder 18 and the chamber 21, hence permitting surging of air under pressure back and forth as valve 10 is operated. Loss of air due to leakage should be reduced to a minimum and a large area is provided for dissipation of heat so that sticking or breakage of the valve stem should be reduced to a minimum. If any breakage should occur it would be of no material importance in the present instance as the valve cannot possibly fall into the cylinder and cause damage.

By referring to Fig. 1, it will be noted that a step is formed in the piston as shown at 5a. This step is provided for the purpose of giving ample clearance for the inlet valve which moves inwardly when opening and also to permit the inlet valve to remain open when the unloader is in operation as will hereinafter he described. The step formed in the piston is substantially the only clearance space formed between the top of the piston and the valves. The clearance space, however, is exceedingly small and in fact is only about twenty-five percent of the clearance usually provided for plate valves of the type heretofore referred to. It should be noted that a shoulder 57) is formed in one side of the cylinder adjacent the inlet valve 9. This shoulder serves as a stop and a retainer for the valve 9 in case of stem breakage and as such should eliminate the danger of the inlet valve falling into the cylinder. In fact it would be impossible for the valve to fall in except if the breakage should occur at a point in the valve stem below the valve guide and as breakage usually takes place above that point there is comparatively little, if any, danger of the inlet valve falling into the cylinder.

By referring to Figs. 1 and 2, an unloader mechanism is disclosed. It comprises a cylinder 30in which is mounted a piston 31. This piston is connected with a rod 32 and a spring 33 is interposed between the lower end of the piston and the cylinder to normally hold the piston in the elevated position shown in Fig. 1. Pivotally secured to the lower end of the rod is a link 34. This link is secured to one end of a cam 35 which is pivoted as at 36. The cam 35 'engagesa collar 37 secured on the pusher rod of the inlet valve and when cam 35 is swung in the direction of arrow a it engages the collar and elevates it together with the pusher rod so as to retain the inlet valve open. In actual practice there are two cams such as shown at 35 and two links 34, there being one cam and link for each inlet valve and if more than two air compressor cylinders are employed the number of cams and links may be proportionately increased. The unloader piston 31 is operated by a pilot valve of standard construction. There are a number of different types of pilot valves, hence no illustration has been made. The pilot valve, as is well known, is connected to the air receiver by a pipe and delivers instantaneous receiver pressure to the unloading device or piston 31 when a predetermined pressure is reached in the receiver. When such predetermined pressure is reached air pressure causes piston 31 to travel in a downward direction. Such movement is transmitted through links 34 to the cams 35 and both inlet valves are accordingly opened and held in their open position, conversely, if the receiver drops below a predetermined pressure the air above piston 31 is instantly released and the piston is returned to normal position by spring 33. The movement of the links 34: and cams 35 is thus reversed and the inlet valves are again permitted to function in a normal manner.

Summarizing the present invention the following advantages should be noted: First, a compressor unit is provided which is adapted for direct connection or integral construction with an internal combustion motor or the like; secondly, mechanically actuated valves are provided; third, a standard type of poppet valve with large area and lift is provided; fourth, chances of the valves dropping into the cylinders due to breakage of the valve stems or otherwise is reduced to a minimum; fifth, clearance space between the piston and the cylinder head or the valve mechanism carried thereby is reduced to a minimum and volumetric efficiency of the compressor should accordingly be great and the overall efliciency proportional; sixth, in a direct connected unit such as here shown the valves may be operated by an extended cam shaft and by providing double lobes two-cycle operation is possible; seventh, lubrication of the compressor unit is reduced to a minimum as the engine lubrication system may be extended to take care of the compressor; eighth, the problem of unloading when predetermined receiver pressures are obtained has also been materially simplified as a simple unloading mechanism is provided whereby the inlet valves may be held in open position without interfering with the operation of the cam shaft or the discharge valves.

While certain features of the present invention are more or less specifically described, I wish it understood that various changes may be resorted to within the scope of the appended claims. Similarly, that the mate rials and finishes of the several parts employed may be such as the manufacturer may decide, or varying conditions or uses may demand.

Having thus described my invention, what I claim and desire to secure by Letters Patent is- 1. In a structure of the character described a four-cycle internal combustion engine having an extended crank shaft and cam shaft, an air compressor cylinder having a piston driven by the extended crank shaft, an inlet and a discharge valve in communication with said cylinder, a pair of camson the extended cam shaft, and means actuated by said cams whereby the inlet and discharge valves are opened and closed in timed relation to the closed in timed relation to the movements of the piston, an unloader mechanism, and means actuated thereby to retain the inlet valve in an open position.

3. An air compressor comprising a cylinder, a piston reciprocally mounted therein, an inlet and a discharge valve, said discharge valve opening outwardly and the inlet valve inwardly with relation to the cylinder and said piston having a recess formed therein to provide clearance for the inlet valve, mechanically actuated means whereby the valves are opened and closedonce during each reciprocal movement of the piston and in timed relation thereto, an unloader mechanism, and means actuated thereby retaining the inlet valve in an open position.

4. An air compressor comprising a cylinder, a piston reciprocally mounted therein, an inlet and a discharge valve, said discharge valve opening outwardly and the inlet valve inwardly with relation to the cylinder and said piston having a recess formed therein to provide clearance for the inlet valve, mechanically actuated means whereby the valves are opened and closed once during each reciprocal movement of the piston and in timed relation thereto, a receiver in communication with the discharge valve, a check valve intermediate the discharge valve and the receiver, an unloader mechanism, and means actuated thereby for retaining the inlet valve in an open position.

5. In a compressor of the character described a cylinder and a head, a discharge valve mounted in the head and opening outwardly with relation to the cylinder, a stem secured to the valve, a piston secured on the stem, a cylinder in the head through which the valve stem projects and in which the valve stem piston reciprocates, a spring normally retaining the valve in closed position, and mechanically actuated means for opening the valve against sprin tension.

6. In a compressor of the character de scribed, a cylinder and piston reciprocally mounted therein, an inlet and a discharge valve in communication with the cylinder, a pair of rocker arms one for each valve, pusher rods whereby the rocker arms are ac tuated to open the valves, a pivotally mounted cam, an unloader mechanism, means Whereby movement is transmitted from the unloader to swing the cam about its pivot, and a collar on the inlet valve pusher rod With which said cam engages to retain the inlet valve in an open position.

7. In a compressor of the character described, a valve, a seat with Which'it co-operates, a stemon the valve, a piston secured to the stem, a cylinder through which the valve stem extends and in Which the piston operates, a spring normally retaining the valve in closed position on its seat, and a rocker arm engageable With the stem and adapted to open the Valve.

AUSTIN J. RIX.