Patent GB-685289-A (GB)
Title: A reciprocating piston and slide engine and pump and the like
IPC: F02B75/28
Filed: 1948-08-04
Abstract: 685,289. Steam engines, driving gear; engine valve gear. SMITH, D. D. FENTON-, and SMITH, P. M. FENTON-. Sept 5, 1949 [Aug. 4, 1948], No. 20551/48. Classes 122(i), 122(ii), and 122(iii) [Also in Groups XXVII, XXVIII, and XXIX] An internal-combustion engine, a gas generator for a turbine, a steam engine, a hydraulic pump or motor, an air compressor or an air pump comprises a cylinder closed at each end, a pair of slides spaced apart and joined at their ends by plates reciprocating in the cylinder, and a piston reciprocating in the space between the slides. Fig. 1 and 4 show an air-cooled and a water-cooled internal-combustion engine respectively and Fig. 7 to 9 (not shown) an air compressor. As shown, slides 2 joined by end plates 4 reciprocate in a cylinder 1, and a piston 3 works in the space between the slides, the parts being square or rec tangular in cross-section. Four working spaces are thus provided, i.e.: one at each end of the cylinder between a cylinder cover and a slide end plate, and two bounded by the slides, two sides of the cylinder, the slide end plates and the piston. The outer working spaces may form charging or scavenging chambers for a two stroke engine the inner spaces forming combustion chambers, or the outer may form first stage and the inner second stage chambers for an air compressor. One end may be an engine, and the other an air compressor driven thereby, also, an internal-combustion engine may be combined with a steam engine. The piston and slide strokes may be equal or unequal. As shown, the swept volumes of the outer and inner chambers are equal, the end plates 4 being flush with the slides 2. The end plates 4 may be wider than the slides as shown in Fig. 4, thus increasing the swept volumes of the outer chambers and providing four additional chambers. Working spaces of different volumes may also be provided by using a stepped cylinder. Clearance volumes. The clearance volumes in the outer charging and scavenging chamber may be reduced by providing recesses 92 inside the cylinder covers 5 and projections 93 on the end plates 4. Similarly, clearance-volume recesses are formed in the piston. Valves and ports. Admission of air to the outer chambers, Fig. 1, is controlled by rotary valves formed by a part-circular web 122 on the crankshaft, transfer to the combustion chambers being controlled by ports 104, 105 in the slides and cylinder walls respectively. In Fig. 4, spring-pressed discs 95 with scalloped peripheries mounted between the parts of two-part cylinder covers act as automatic air-inlet valves, transfer ports 115 and exhaust ports 108 being formed in the cylinder. In the air compressor of Fig. 7 (not shown) poppet valves control delivery. Spring-pressed sealing rings 106 of circular, wedge-shaped or rectangular cross-section retained in grooves surround the ports. Piston. The piston consists of two crowns 61 having rounded edges and joined by a bar 62 of rectangular or I section, or integral therewith. The spaces between the plates and the bar accommodate the webs of a main crankshaft. Sealing strips 72, 79, Fig. 2, of rectangular, wedge-shaped or L-shaped section are mounted in grooves in the piston and the bar respectively, adjacent oil grooves: coil or corrugated springs in the grooves act on the strips. The piston 3, sealing strips and bar 62 are made of cast iron, steel or alloys thereof The strips may act as oil scrapers, or scrapers may be provided. Slides and end plates. The end plates may be integral with the slides or connected thereto by screws. The slides may carry spring-pressed bearing plates 81, Fig. 1, mounted in grooves and contacting the cylinder walls. Sealing strips under spring pressure may be mounted in grooves in the slides and end plates. The strips and bearing plates may be made of cast iron or steel or their alloys, and the slides and end plates of magnesium or aluminium alloys. The slides and end plates may have rounded edges corresponding with those on the cylinder and the piston heads. Cooling. Fins 82, Fig. 1, on the cylinder provide for air cooling, the cylinder being enclosed in a duct 83 each end of which is welded to a ring 84 spigoted on a cylinder cover 5, rings 85, 86 being welded to the duct and spigoted on a main-bearing carrier 44 and cap 57 respectively. Cooling air enters by intakes 87 and leaves by apertures on the opposite side of the cylinder. For liquid cooling, a water jacket 88, Fig. 4, is similarly fixed to the cylinder. Driving the main shaft. The slides 2 and piston 3 have slots to receive slidable blocks 13, 14, Fig. 1, which have bearings for crank pins on a crankshaft. Outer crank pins 7 are connected to the slides and an inner crank pin 8 to the piston. Crank-webs 11, 119 are situated two (11) between the piston and slides and two (11, 119) outside the slides. Plain bushed, ball, roller or needle roller bearings may be provided for the crank pins and crankshaft. As shown, inner and outer races are mounted in a housing 51 spigoted into a casing 48 fixed in the cylinder wall, oil seals 50, 52 being provided. In place of a crankshaft, a shaft carrying eccentric sheaves engaging slider blocks in the piston 3 and slides 2 may be used. Balancing. The pistons 3 and slides 2 reciprocate in opposite directions, the sum of the masses of the slides being equal to the mass of the pistons. Where the strokes of the pistons and slides are unequal, the combined mass of slides and end plates multiplied by the linear accelerations at any given time must equal the product of the mass of the pistons and linear acceleration at that time. The centre of the combined mass of the slides and their end plates and the centre of mass of the piston lie on the cylinder axis. The crank-webs outside the slides may be extended to form balance weights 12, Fig. 4. Main shaft mounting. The crankshaft, Fig. 1, is supported in three main bearings:- (1) a ball bearing 25, the inner race 28 of which is fixed on the shaft and the outer race 35 in the carrier 44 which is bolted to the cylinder wall; (2) a roller bearing 24 the inner race 27 of which is mounted on a sleeve 30 fixed on the shaft and the outer race 34 mounted in a cap 51 bolted to the casing 48 which is bolted to the cylinder wall and encloses accessories &c., distance collars 54, 56 being provided between the bearings 27, 28 and between the bearing 27 and a nut 55 respectively; (3) a roller bearing 26 comprising an inner race 29 on the shaft and an outer race 36 mounted in a sleeve 37 let into the cylinder wall, the aperture in which for the shaft is covered by the cap 57: a collar 59 bolted to the shaft holds the race 29 in position. Oil seals 50, 52, and 58 are provided. In Fig. 4, inner race tracks are formed on the shaft itself, and the cap 57 and casing 48 retain the outer races in position, and in Fig. 7 (not shown) a main shaft carrying eccentric sheaves is mounted in two needleroller bearings, one outer race being housed in the cylinder wall and the other in a bearing carrier.