US2373779A - Multistage compressor - Google Patents

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P 'I $19745 H. R. RICARDO v 2,373,779

IIULTIS'IAGE cournnsson.

Fil'ed Sept. 16, 1942 s Sheets-Sheet 1 v April 1945. H. R. RICARDO 2,373,779

- MULTISTAGE COMPRESSOR Filed Sept. 16, 1942 s Sheets-Sheet 2 F/G.3.j

{1 i f Q t i H- F a 1 D/ i Q Fl H/ Q r 0/ Q H2 I g Invent By If M ttorney Patented Apr. 17, 1945 UNITED STATES PATENT O R MULTISTAGE COMPRESSOR Harry Ralph Ricardo, London, England Application September-16, 1942, Serial No. 458,547

In Great Britain September 29, 1941 6 Claims. (Cl. 230-184) This invention relates to multi-stage compresject to provide a compact and simple construction adapted more especially for the compression of air or gas. According to this invention in the compressor a higher rotational speed is employed than in the subsequent stages, the first stage being operated by a crankshaft which is rotated at a speed greater than that of the crankshaft by which are operated the pistons of the subsequent stages. There is at least one cylinder with piston therein constituting the first stage this piston being reciprocated by a crankshaft driven at relatively high speed and pistons in cylinders constituting the subsequent stages which are reciprocated by a second crankshaftthe first stage of 'sors of the reciprocating type and has for its obdriven at a lower speed and conveniently through gearing from the first crankshaft. The valves of each cylinder in the first stage are positively actuated mechanically, while the valves of the cylinders in each subsequent stage operate automatically. These inlet and delivery valves. of the first stage are of the piston type and areoperated by a shaft rotating at half the speed of the crankshaft of the first stage, and the opening and closing of the inlet and delivery ports is effected while these piston valves are moving at their maximum velocity, that is during the middle portion of the stroke of each valve. Thetshaft which operates these piston valves is conveniently the crankshaft which reciprocates the pistons in the cylinders of the subsequent stages these cylinders and pistons being disposed coaxially with the piston valves to which those higher stage pistons are connected so that they are actuated through the valves. Each of the latter thus acts as a cross-head towhich is connected on the one hand the piston of a higher stage and on the other hand a connecting rod running from a crank on the second crankshaft. In a convenient arrangement the delivery valve of the first stage is connected to and serves as a cross-head for the piston of the third stage, this valve being actuated from a crank on a crankshaft driven 1 through gearing at half speed from the crankshaft which operates the first stage. To a second crank on this half speed crankshaft isconnected 'the inletor suction valve of the first stage cylinder and this valve in turn acts as a cross-head for and is connected to the piston of the second stage cylinder. .From this piston mayextend a plunger which reciprocates in the cylinder of a fourth stage. This latter may be omitted if the may be referred to as the main crankshaft while compressor is constructed with only three stages.

Suitable intercoolers may be provided between the various stages, and an aftercooler may be provided to cool the gas delivered by the last or highest stage. i

The accompanying draw gs illustrate diagrammatically and by way of example a construction of four-stage compressor according to this inven- Figure 2 is a planof the compressor shown in Figure 1. v

Figure 3 is a transversevertical section on the line 3-3 in Figure l, and the broken line-33 in Figure 2, the section showing the piston and cylinder of the first stage, the inlet valve therefor, and the cylinders, pistons and valves ofthe second and fourth stages.

"Figure 4 is 'a vertical section similar to Figure 3, but taken on the-line l,--& in Figure 1 and .on the broken line 4-4 in, Figure 2', and'show ing the piston and cylinder of the first stage,

the delivery valve for that cylinder, and the cylin- -der and piston of the third stage.

. There are two crankshafts of which" the one 'A the other B may .be' referred to as the second crankshaft or layshaft. The compressor is'driven by power applied in some convenient manner and from asuitablesource to the main shaft A, and the layshaft B is driven by gearing C from the shaft A so that the. layshaftB will be rotated at half the speed of the main shaft These'two' shafts A and B are parallel and atno, great dis-,

tance apart with the axis of the shaft B lying a horizontal plane above the similar plane in w ch lies the axis of the shaft A, as can be seen m Figures and 4. The vertical plane in which lies the axis of the shaft B and'the axes of the pistons driven from that shaft is set back behind the vertical plane in which lies the axis of the cylinder of thefirst stage as can be seen in Fig- -ure 2 as-well as in Figures 3 and 4. Considered in plan, as seen in Figure 2, the cylinder D of the first stage with the piston E therein appears as having at one side of it the cylinders F and G with the piston valves H and J therein. Coaxial with the cylinder F'and above itare the cylinder elevation of the I K of the second stage with the piston L reciprocating therein, and the cylinder M of the fourth stage with the plunger piston Ntherein. Coaxial with the cylinder G and above it is the cylinder of the third stage with the piston P which is reciprocated in it.

Th piston valves of the first stage are hollow and the suction valve H. controls an inlet port D to the first stage cylinder D and an inlet port F from the atmosphere to the valve cylinder F as seen in Figure 3. The valve J controls the delivery port D from the cylinderD and the compressed air passes through the valve J and cylinder G into the passage G which communicates conveniently with an intercooler of suitable type which is not shown in the drawing. From this first stage intercooler the air passes the suction valve K into the secondstage cylinder K whence it is delivered past the delivery valve K to a second intercooler, also not shown in the drawing. From this second stage intercooler the air goes past the suction valve 0 into the third stage cylinder 0 and thence past the delivery valve 0 to a third stage intercooler which is not shown. Finally the air enters the fourth stage cylinder M past the valve M and is delivered past the valve M i The hollow piston valves H and J are substantially similar in their general structure with ports formed in the walls of their upper parts. In the valve H which functions also as a cross-head, is a partition H below which is carried the gudgeon pin H through which the valve is connected to the crankshaft B. From this partition'H a coupling rod Q extends tothe piston L of the second stage. This coupling rod has'curved faces at its ends which engage correspondingly curved bearing blocks carried respectively by the partition H andthe piston L. By suitable means the ends of the coupling rod are maintained in'engagement with the curved seats in these blocks. The arrangement obviates difficulty which might arise owing to some lack of alignment between the clinders F and K. There is a similar coupling rod between a partition J in the piston valve J, which also functions as a cross-head for the gudgeon pin J and the piston P of the third stage.

By leading the air from the first stage cylinder D into the end of the cylinder G beneath the piston P in the'c-ylinder O of a higher stage the pressure difference is reduced on the rings of the piston of the higher stage.

There may be a throttle valve of suitable form .in the induction passage leading to the suction valve inlet port F In'the head of the cylinder D stage cylinders are of some type which will operate automatically. In the case of the second stage cylinder K each of the valves K and K" is a disc -which is mounted freely, except for a light spring, between a perforated seat member and a retaining member. The ports controlled by these valves are in the head of the cylinder K. with regard to the third stage the piston P is of trunk form with the trunk of substantial length. The' end of the cylinder 0 and the face of the piston are conical the ports being in the sloping end of the cylinder. The inlet valve 0 is preferably of the poppet type and the delivery valve 0 is a disc acted on by-a spring.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a multi-stage compressor of the reciprocating type the combination of at least one cylinder with piston therein constituting the first stage of the compressor, at least one other cylinder with piston therein constituting a subsequent stage, a crankshaft to which is connected the piston in the said cylinder of the first stage, a second crankshaft to which is connected the piston in the said cylinder of a subsequent stage,

. shaft is driven.

2. In a multi-stage compressor of the reciprocating type the combination of at least one cylinder with piston therein constituting the first stage of the compressor, at least one other cylinder with piston therein constituting a subsequent stage, a crankshaft to which is connected the piston in the said cylinder of the first stage, a second crankshaft to which is connected the piston in the said cylinder of a subsequent stage, valves associated with the said cylinder of the first stage, means by which these valves are actuated from the said second crankshaft, valves associated with the said cylinder of a subsequent stage with means by which these valves are actuated automatically, and means whereby the said second crankshaft is rotated at a speed which is less than the speed at which the said first crankshaft is driven.

3. A multi-stage compressor of the reciprocating type comprising the features as set out in claim 2 in which piston valves connected to and reciprocated by the said second crankshaft function as the inlet and delivery valve of the said cylinder of the first stage.

4. In a multi-stage compressor of the reciprocating type the combination of at least one cylinder with piston therein, constituting the first stage of the compressor, at least' two cylinders each with a piston therein and constituting subsequent stages of the compressor, a crankshaft to which is connected the piston in the said cylinder of the first stage, a second crankshaft to whichare connected the pistons in the cylinders of the subsequent stages, piston valves connected to and reciprocated by the second crankshaft these valves functioning as the inlet and delivery valves of the said cylinder of the first stage and being respectively coaxial withthe cylinders of the higher stages, valves associated with the said cylinders of stages subsequent to the first stage with means by which these valves are actuated automatically, and means whereby the said second crankshaft is rotated at a speed which is less than the speed at which the said first crankshaft is driven.

5. In a multi-stage compressor of the reciprocating type the combination of at least one cylinder with piston therein constituting the first sta e of the compressor, at least two cylinders each with a piston therein and constituting subsequent stages ofthe compressor; a crankshaft to which is connected the piston in the said. cylinder of the first stage, a second crankshaft to which are connected the pistons in the cylinder of the subsequent stages, piston valves connected to and reciprocated by the second crankshaft these of the said cylinder of the first stage and being respectively coaxial with and acting as crossheads for the pistons in the cylinders of the higher stages, valves associatedwith the said cylinders.

. valves functioning as the inlet and delivery valves of stages subsequent to the-first stage with means I by which these valves are actuated automatically, and means whereby the said second crankshaft is rotated at a speed which is less than the speed at which the said first crankshaft is driven.

' 6. Ina multi-stage compressor of the reciprocating type; the combination with at leastone cylinder with piston therein constituting the first stage of the compressor, at least two cylinders f each with piston therein and-constituting subsequent stages of the compressor, at least, two of these cylinder of subsequent stages being coaxial with the pistons therein connected,'a crankshaft.

to which is connected the piston in the said cyl- 1 inder of the first stage, a second crankshaft to 1 matically, and means whereby the said second crankshaft is rotated'at a speed which is less than the speed at which the said first crankshaft is driven, 20

HARRY RALPH RICARDO.

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