US1925544A - Air compressor - Google Patents

Description

A. J RIX AIR COMPRESSOR Sept. 5, 1933.,

Filed Feb. 9, 1952 3 Sheets-Sheet 1 IN! "EN TOR.

BY A T A 7 TYR V QYS Sept. 5, 1933. A. J. RIX I 1,925,544

AIR COMPRESSOR Filed Feb. 9, 19:52 3 Shets-Sheet 2 Fig. r2.

INVENTOR.

M ZW

A T 72155 S.

Sept. 5, 1933. A. J. RIX 1,925,544

AIR COMPRESSOR Filed Feb.- 9, 1932 3 Sheets-Sheet 3 INVENTOR.

@ J/ BY p W v Q/ mf/MMV Ma??? Patented Sept. 5, 1933 STATES .PATEN This invention relates to air compressors, and particularly to improvements in the valve mechanism shown in my Patent Number 1,819,691 entitled Air compressor i sued August 13th,

The valve mechanism disclosed in the patent above referred to embodies an inlet and a discharge valve of a poppet valve type, said valves being normally held in closed position by springs and being'mechanically actuated to insure positive opening anclclosing of the same. Valves of this type are fairly heavy and as compressors of this character operate at high speeds, such as 1000-R1.'P. M. or greater, inertia forces of an excessive nature are produced causing hammer action of the valves, spring breakage, excessive wear, etc., this being particularly true of the discharge valves as they are heavier due-to the differential counter-pressure pistons employed.

The object of the .presentinvention is togenerally improve and simplify the construction and operation of'valve mechanisms of thecharacter described, and particularly to provide a differential pressure counter-balanced discharge valve adapted: to be automatically opened during the compression stroke of the compressor by the pressure of the fluid compressed during the compression stroke, and to providemeans for positively closing the discharge valve by cam action or the like during the suction stroke.

The compressor, together with the valve mechanism employed, is shown by way of illustration in the accompanying drawings, in which Fig. 1 is aside elevation of a direct connected engine and air compressor, said side elevation being partially broken away and sectioned to show certain parts of the mechanism.

Fig. 2 is a vertical cross section of one of the air compressing cylinders.

Fig. 3 is an enlarged detail section of the discharge valve and a part of its actuating mechanism.

Fig. 4 is a section similar to Fig. 3, showing a modified form of the discharge valve and actuating mechanism.

Fig.5 is an enlarged view of the cam whereby the discharge valve is mechanically closed.

Fig. 6 is an enlarged view of the. double lobe r cam whereby the inlet valve is actuated.

Referring to the drawings in detail, and particularly Fig. 1, A indicates the cylinders of an internal combustion engine of the four cylinder type, B the crank shaft, and C the cam shaft which, in this instance, is driven from the crank shaft by gears 2 and 3 in the usual manner to maintain a speed ratio between the crank and cam shafts of 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 pairof 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 '2, the pistons 5 will be connected through rods 8 with the respectivecranks and as such will operate in unison with the pistons and the cylinders indicated at A.

The compressor 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. The inlet valve is mechanically operated to insure positive opening and closing of the same, while the discharge valve is automatically and pneumatically opened during the compression stroke of the compressor and mechanically closed during the suction stroke.

- The valves employed are of the poppettype, such as used in automotive practice, the inlet valve being opened inwardly in the usual man ner and being operated by a rocker arm 9a. The rocker arm is operated by apusher rod, such as shown at 11, and this is, in turn, actuated by the extended cam shaft C, which is identical to any ordinary cam shaft with the exception that double lobe cams such as shown at- 12 are employed in connection with the inlet valves, while cams of the concave type, such as shown inFig. 5, are employed in conjunction with the discharge valves. Double lobe and double concave cams are required due to the fact that the cam shaft operates at a one to two ratio, as the valves must be opened and closed once during each revolution of the crank shaft while the valves on-the engine proper are merely opened once during two revolutions of the crank shaft.

The discharge valves 10, together with the mechanism actuating the same, form the subject matter of the present application and are best illustrated in Fig. 3. By referring to this figure and Fig. 2, it will be noted that the valves are of the poppet valve type and that they open outwardly with relation to the cylinder. The head G of the cylinder is provided-with discharge passages 14 which are connected in any suitable manner with a receiver, not here shown, and when valves 10 are opened duringthe discharge stroke of the main pistons air will enter the passages 14 and discharge therefrom into the receiver. Necessary pressure will, however, always be maintained in the discharge passages 14 and means must accordingly be provided forcounter-balancing the pressure exerted on top of the valves 10 as the pressure in the passages 1 will often exceed one hundred pounds gauge or more per square inch of exposed valve area. To counter-balance this pressure the heads G are provided with cylinders, such as indicated at 15, and each cylinder carries a piston 16. The pistons are welded, or otherwise secured, to the stems 17 of the valve 10 as indicated at 18 and as such move in unison with the valves 10 whether these are opened or closed. The pistons 16 are provided with rings, such as shown at 16a, to reduce leakage to a minimum and they are suitably lubricated through an annular surrounding passage, such as shown at 19. The pistons 16 present an area slightly less than the area presented by the valves 10 so that the pressure within the passages 14 will be sumcient to maintain the valves closed or on their seats, hence eliminating the necessity of employing any springs for this purpose.

The discharge valves 10 are, as previously stated, adapted to be automatically and pneumatically opened by air pressure and, conversely, to be mechanically closed. Each valve 10 is accordingly provided with a rocker arm 20 pivotally supported on top of the head GQas indicated at 21. Each rocker arm is provided with a pusher rod and tappet, such as indicated at 22, and the pusher rods are, in'turn, actuated by the concave cams indicated at 23, these cams permitting automatic opening of the valves and at the same time providing the means whereby the valves are mechanically and positively closed during the suction stroke. A spring 24 is interposed between each rocker arm 20 and the head G and the function of these springs will hereinafter be described.

In actual operation the inlet valves will function in the usual manner, that is, they are actuated by the double lobe cams and as such will be opened during the suction stroke of the pistons and will be automatically closed by means of the springs during the compression stroke. The discharge valves 10, on the other hand, will function in an entirely different manner, as they are automatically and pneumatically opened. This is accomplished as follows: When the main pistons travel downwardly during the suction stroke, the inlet valves are opened and the cylinders are filled with air or any other fluid to be compressed. During the upward or compression stroke the inlet valves close and the air or fluid, which has previously entered, will accordingly be compressed and when a predetermined pressure is reached, depending upon the diiTerence in area between the valves 10 and the counter-balancing pistons 16, valves 10 will open due to the fluid pressure exerted on their lower surfaces. The concave portions of the cams, indicated at 26, will at this time register with the pusher rods 22, hence permitting the valves 10 to open by air pressure and to transmit movement through the rocker arms 20 to force the pusher rods downwardly toward the bottom of the concaves 26. The moment the air or fluid has been discharged, the opposite sides of the concaves, indicated at 27, engage the pusher rods and the valves 10 are, accordingly, positively closed, and when closed will remain closed due to the air pressure in the discharge passages 14 and also due to the rounded contour portions 28 of the earns 23. Hence,

it will be noted that the discharge valves are automatically opened by the pressure of the fluid being compressed during the compression stroke and that they are mechanically closed by the cam portions 27 during the commencement of the suction stroke. The automatic opening of the valves by the pressure produced Within the cylinders is of great importance as it permits opening of the valves before the air pressure within the cylinders becomes very great, hence permitting the valves 10 to open slowly as the pressure builds up thereby reducing inertia forces to a minimum.

Compressors of this character are usually provided with an unloader mechanism and, as any desired type of unloader mechanism may be employed, specific description thereof is thought unnecessary. Suffice it to say, that when the unloader mechanism operates, the inlet valves are maintained in open position permitting the air or fluid to be compressed and to enter and freely discharge, or in other words to surge back and forth between the inlet valves. Under such conditions, the discharge valves 10 here shown will not open as compression pressure is not produced in the compressing cylinders. The cam shaft, however, continues operation and the rocker arms and pusher rods 22 whereby the discharge valves are operated would accordingly have a tendency to jump and hammer with relation to the cavities 26 formed in the cams 23, said jumping or hammering is entirely avoided in the present instance by introducing the springs 24, as the tension thereof will cause the rocker arms and pusher rods to follow the contour of the cams 23 just as surely as if the valves 10 were being operated.

While diilerential'pistons 16 are shown in the main views of the drawings, it is obvious that similar results maybe obtained by the use of a flexible diaphragm, such as indicated'at 16a in Fig. 4. This type of diaphragm permits opening and closing of the valve and permits counter loo ill)

balancing of the same and as such functions substantially in the same manner as the piston 16; and while other featuresof the invention are more or less specifically described and illustrated, I wish it understood that various changes may be resorted to within the scope of the appended claims. Similarly, that the materials and finish of the several parts employed maybe such as the manufacturer may decide, or varying con ditions or uses may demand.

Having thus described my invention, what I ice with. a receiver so as to containfluid under receiver pressure, a discharge valve in the head and interposed between the cylinder and the discharge passage, said valve being mechanically closed and being maintained in closed position by mechanical means and also by the fluid pressure in the discharge passage, means cooperating withthevalve I charge passage formed therein in communication with the receiver so as to contain fluid under receiver pressure, a discharge valve in the head and enclosed between the cylinder and the discharge passage, a piston in the cylinder adapted to compress fluid and by compression of the fluid adapted to open the discharge valve against the fluid pressure in the discharge passage, means on the valve for partially counter-balancing the fluid pressure in the discharge passage and mechanical means for closing the valve.

3. An air compressor comprising a cylinder and a head, a piston in the cylinder, a crank shaft whereby reciprocal movement is transmitted to the piston, a cam shaft driven by the crank shaft, an. inlet and a discharge valve in the head and communicating with the cylinder, a double lobe cam whereby the inlet valve is opened during each suction stroke of the piston, said discharge valve adapted to be pneumatically opened during each compression stroke of the piston, and a cam on the cam shaft having a pair of depressions formed therein permitting pneumatic opening of the discharge valve said cam also functioning to positively close the discharge valve during each suction stroke of the piston.

In a compressor of the character described, a cylinder and a head, said head having a discharge passage formed therein, and adapted to communicate with a receiver so as to maintain recured on said stem and having an area slightly 7 less than the area presented by the valve so as to partially counter-balance pressure on the valve, and means for positively closing the valve during each suction stroke of the piston.

5. In a compressor of the character described, a valve, a seat with which it cooperates,'a stem on the valve, said valve forming communication between a cylinder and a discharge passage in which is maintained receiver pressure, a piston secured to the stem of the valve and having an area slightly less than the area of the valve, said piston being exposed to receive pressure so as to partially counter-balance pressure against the valve, a rocker arm cooperating with the stem, and a cam whereby the rocker arm is actuated, said cam having a depression formed therein permitting pneumatic opening of the valve and said depression also functioning to positively close the

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