US2458198A

US2458198A - Control for spill ports for freepiston units

Info

Publication number: US2458198A
Application number: US531308A
Authority: US
Inventors: David M Poole
Original assignee: United Aircraft Corp
Current assignee: Raytheon Technologies Corp
Priority date: 1944-04-15
Filing date: 1944-04-15
Publication date: 1949-01-04
Anticipated expiration: 1966-01-04

Description

Jan. 4, 1949. D. M. POOLE 2,458,198

CONTROL FOR SPILL PORTS FOR FREE-PISTON UNITS Filed April 15, 1944 INVENTOR oAvuo M. POOLE mam.

ATTORNEY d) N n Patented Jan. 4, 1949 UNITED STATES PATENT OFFICE CONTROL FOR SPILL PORTS FOR FREE- PISTON UNITS Application April 15, 1944, Serial No. 531,308

This invention relates to a free-piston engineand-compressor unit and particularly to a control for the spill ports by which the effective volume of the compressor is adjusted.

The copendinapplication of Cooper, Serial No. 531,301, filed April 15, 1944, describes a freepiston unit, the compressor cylinder of which has a number of rows of openings forming spill ports through which a part of the air in the compressor cylinder is discharged. A featureof this invention is an arrangement for controlling the ports.

When the unit is adapted for aircraft use, and therefore, subject to substantial variations in intake pressure, the unit can best be adapted to these variations by successive closing of the rows of ports. A feature of this invention is an arrangement by which the rows of ports may be individually and successively controlled.

Another feature of this invention is a control for the ports which is compact and will not seriously increase the space requirement for the unit. Another feature is the control of the ports by an axially movable band extending around the compressor cylinder.

Other objects and advantageswill'be apparent 25 from the specification and claims, and from the accompanying drawings, which illustrate an embodiment of the invention.

Fig. 1 is a sectional view through a free-piston unit.

Fig. 2 is a fragmentary view of the activating mechanism for the inner bands.

The unit shown includes an engine cylinder having reciprocating pistons l2 and I4 to which compressor pistons 16 and I8 in

cylinders

20 and 22 are integrally connected. Sleeves 24 and-26.

attached to the compressor pistons complete the reciprocating piston assemblies. The sleeves in combination with stationary pistons 28 and to form air spring cylinders.

The piston assemblies are moved apart by the burning of fuel injected into engine cylinder It through one or more nozzles 32. Air compressed in the air spring cylinders on the power stroke returns the piston assemblies. The assemblies are always maintained at equal distances from the center of the engine cylinder by a linkage, not shown.

Intake manifold 62, which extends around the compressor and engine cylinders conducts air to intake valves 66 in the heads of the compressor cylinders, through which air alternately enters opposite ends of the cylinders. The compressed air leaves the cylinder through discharge valves 48, also at opposite ends of the compressor cyl- 8 Claims. (Cl. 230-56) inders and passes into a central scavenge chamber 48 and

end chambers

50 and 62. These These chambers may be interconnected by a scavenge manifold, not shown.

Compressed gas from the scavenge chambers enters engine ports 54 and 56 which are uncovered by pistons l2 and M at the end of the power stroke, thereby permitting air to be blown through the engine cylinder. Gas and air in the engine cylinders are discharged through exhaust ports 58 into exhaust manifold 60.

Each compressor cylinder has a number of axially spaced rows of spill ports 62 which permit discharge of air from the cylinders without compression. The rows of ports are controlled by 2g and an inner band 65-50 that the inner and outer end rows may be closed before the other rows, and, by selective movement of the bands, the rows or ports may be closed or opened in sequence from opposite ends of the cylinder;

If the unit is used in aircraft, and is designed for altitude operation, the bands are moved so that all the rows of ports are open at sea l v l,

and only a small volume of gas is compressed. As

thedensity of the air decreases (at altitude) one so or more of the rows of ports may be successively closed, beginning with the end rows to increase the efiective volume of the compressor. The several rows of ports permit adaptation of the compressor to substantially any altitude or to any air density.

The bands may be moved manually or they may be moved mechanically. For example, as shown, the outer bands 54 may have inwardly projecting rods 58 carrying, on their inner ends, pistons i0 in a .cylinder 12. For closing the spill ports, fluid under pressure enters the outer ends of the cylinder through a pipe l4 and fluid exhausts through a central pipe 16. If desired, a control mechanism may be used for admitting fluid selectively through pipe 14 or it.

A similar control device may be used for moving the inner bands, the device operating independas the pistons are urged apart to close the inner rows of ports successively from the inner ends of the compressor cylinders.

It is to be understood that the invention is not limited to the specific embodiment herein illustrated and described, but may be used in other ways without departure from its spirit as defined by the following claims.

I claim:

1. A free-piston unit including a compressor cylinder and a piston therein, said cylinder having a cylindrical wall with atleast one row of! circumferentially arranged ports extending therethrough, and a band surrounding. engageable with. and movable on the outer surface'of said 5 inders having a cylindrical wall having a number cylindrical wall to close or operrsaid ports.

2. A free-piston unit including a compressor cylinder and a piston therein, said cylinder having a cylindrical wall with at least one row of circumferentially arranged ports extending therethrough, and a band surrounding. enga in with, and movable axially on the outer surface of said cylindrical wall for opening or closing the 3. A free-piston u'nit including a compressor cylinder and a piston therein, said cylinder having a cylindrical wall with a number of axially spaced rows of ports extending through the wall and arranged circumferentially therein, and at least' one band engageabie with and movable axially on the outer surface of said cylindrical wall for opening or closing the rows of ports-in a predetermined sequence. y

' 4. A free-piston unit including a' compressor cylinder and a piston therein, said cylinder hav ing a cylindrical wall with a number of axially spaced rows of ports extending through the wall 85 and arranged circumferentially therein, at' least one band engageable with and movable axially on the outer surface or said cylindrical wall for opening or closing the rows'of ports-in a prede t'e'rmined sequence, and means for moving said 40 hand axially along the outer surface of the cy linder wall.

s. A free-piston unitincluding an engine cylinder, opposed pistons in the cylinder, compressor pistons moving with the engine-pistons, and opposed compressor cylinders for said compressor pistons located at opposite ends of' the engine cylinder, said compressor cylinders each having a number of axially spaced rows of ports extending through the cylinder, each row extending circumferentiallyaround the cylinder, a' closure means on the outer surface oi each cylinder mov-Q able to close the rows of] ports. and means for moving-the closure means on the opposed com pressor cylinders simultaneously.

- 8. A free-piston unit including cyl- 4 inder, opposed pistons in the cylinder, com pistons moving with the engine pistons, and compressor cylinders for said compressor pistons located at opposite ends of the en ine cylinder, each of said compressor cylinders having a cylindrical wall having a number 0t axially spaced rows of ports. each row extending circumferentially around the compressor cylinder, and a band extending around each compressor cylinder and movable to open or close the ports.

7. A free-piston unit including an engine cylinder, opposed pistons in the cylinder, compressor pistons moving with the engine pistons, and compressor cylinders, each of saidcompressor cylof axially spaced rows of ports extending therethrough, each row extending circumferentially around the compressor cylinder, and a band extending around each compressor .cylinder and movable axially on the compressor cylinder for opening or closing the ports.

8. A free-piston unit including an engine cylinder, opposed pistons in the cylinder, compressor pistons moving with the engine pistons, and compressor cylinders, said compressor cylinders each o axially on the compressor cylinder for opening or closing rows 01 portssuccesslvely. DAVID M. room.

.REFERENCES crrsn The following references, are of record in the dle of this patent:

UNITED STATES PATENTS Number Name Date 877,492 Doelling Jan; 28, 1908 1,481,358 Dwyer Jan. 22, 1924 1,579,782 Riesner Apr. 8, 1926 1,889,787 Trumble Aug. 2, 1932 2,018,613 Pescara Oct. 8. 1935 2,064,976 Janicke Dec. 22, 1936 2,076,258 'Witkrewicz Apr. 6, 1937 2,108,890 Janicke- Feb. 22, 1938 2,134,920 Kadenacy Nov. 1, 1938 2,189,497 Pescara Feb. 6, 1940 2,282,582 Cole May 12, 1942 2,319,588 Sundermanet al. May'18, 1943 FOREIGN PATENTS Number Country Date 68 168,337 Germany 1903 237,170 Germany 1910