US2097742A - Accessory drive mechanism - Google Patents

Description

Nov. 2, 1937. B. D. SCOTT ACCESSORY DRIVE MECHANISM Filed Jan. 8, l9C 5 2 Sheets-Sheet l Nov. 2, 1937. B. D. SCOTT ACCESSORY DRIVE MECHANISM 2 Sheets-sheaf. 2

Filed Jan. 8, 1935 Patented Nov. 2, 1937 AocEssoRY DRIVE MECHANISM Bateman David Scott, Camp, Miscrd'en, near Stroud, England Application January 8,

In Great Britain 1935, i n No. January 8, 1934 3 Claims. (Cl. 123-495) This invention relates to accessory drive mechanism more particularly of the kind adapted for use in aircraft propulsion.

The main obj ect of the invention is to provide an improved vibrationless accessory drive.

Other objects will be evident from the descrip-v tion which follows.

In all heavier-than air aeroplanes propelled by internal combustion engines the torque reaction imposed upon the structure constitutes a constantly varying disturbing factor according to the power being transmitted.

counteract this rotate the aeroplane about and thereby upset the machine in flight, means have been proposed which however are only In order to tendency of the power unit to its centre of gravity effective at a certain air speed. Suchan arrangement results ing surfaces not and also for the reason in losses of efliciency due to the liftbeing equal in angle of attack; that the tendency to upset the machinein mid-air has to be neutralized by motion imparted to the ailerons by the pilot.

' able importance 3 the torque reaction in ing surfaces.

particularly in those where Torque reaction assumes considerin machines of large size, and the power units have been built into the wings.

These and other disadvantages are avoided according to the present invention by balancing power unit. By

the engine itself of the this means, at no time does the said force become a disturbing factor even under full throttle, and be set at their most of erection and subsequent checking by. the

further, all surfaces may efficient angles at the time ground engineers reduced to a minimum. Again,

there is perfect safety in regard to torque reaction at a time when making .power dives,;and the wings momentarily are not acting as lift- In order that the invention may be clearly understood, reference will now be made to the accompanying drawings of example, an e which illustrate, by way mbodiment of a unit, like references applying to similar parts in the various figures.

In these drawings:

Figure l is a sectional elevation of an internal combustion engi arranged in pairs ne, the cylinders of which are with separate crankshafts,

Figure 2 is a front elevation of the X or spider frame cam-shaft driving mechanism,

Figure 3 is a part sectional elevation of same. A common arrangement of a propulsion unit in aeroplanes is assembled in pai central plane of one in which the cylinders are rs on opposite ,sides'of the main the unit. The engines may operate on the four-stroke cycle or they may, for

example, operate upon a five-phase four-stroke cycle as explained hereinafter.

of the cylinders preferably set at an angle The centre lines which constitute one pair are to each other in the form of aninverted V, in parallel planes at rightangles to the axes of the crankshafts.

Figure-1 shows an engine unit for of the above character comprising a rangements pair of cylinders side-by-side, at an angle to e ends connecting pression and explosion chamber d3. tons 44, 4-5 are adapted to reciprocate together 1 in the same directiomby and outstrokes in unison,

use in ar- M, e2 cast in one and arranged preferably with their centre lines ach other, the two compression so that there is a common com- The pisefiecting their instrokes the connecting rods 41 being, connected each to a separate crankshafti8, 49;- "This arrangement advantages in single acting en- H and has certain is known per se gines, In the arrangement shown, the axes of the crankshafts are set closer together than the distance between the points of intersection of the centre-lines zontal plane; containing with the horiof the cylinders the crankshafts.

means of gear wheels which are keyed on the respective chankshafts 48 and 49 and interengage, the crankshafts rotate in opposite directions,;whereby there is cancellation of the torque reaction due to the running of the engines.

j, In the common explosion chamber above the cylinders are valves 56 and W controlling the admission and exhaust gases.

valves is effected Control of the by means of twin cams 58 and 59 mounted respectively on separate overhead cam-shafts 60 and iii arranged parallel with each other.- The twin and gjboth; are in the same ing the cam-shafts. directly upon its valve, a rocker or lever, of the twin cams disposed at 180 apart plane thereby balanc- Preferablyy each cam acts but it may act through if desired. The arrangement further permits of slow runcams are ning of the cam-shafts and silence in working with a gear ratio of usual 2 to 1 ratio,

wearing surface.

springs 62 provide The cam-shat 4 to 1, instead of the more while providing double the Simple or compound helical for the closing of the valves. ts E0 and 6! are operated by means of a single X shaped spider or frame 63 (Figures 3 and 4) arranged in a timing casing 64 preferably in engine. are indicated by small pinions 48' and 49 two idler wheels The rear ends of the rear end of the the two crankshafts 48 and 49, upon which are keyed that are geared to 65 and 66. Idler wheel 65 enounted at gages with the 4 to 1 wheel 66' mounted in ballbearings on casing 64 and this wheel has a crank 61 which carries the spider frame 63. This frame transmits rotary motion to the cam-shafts 60 and 6! through crank discs 68 and 69 and pins H3 and l I, and also transmits motion to the spindles of twin oil pumps through crank discs l2, l3 and crank pins 72 and 13.

Subsidiary spider frames 14 and 15 of triangular shape provided in the timing casing 64 are driven by crank pins 16 and 11 and these frames are used to transmit rotary motion to shafts 7'8, 19, so and 8!, for the purpose of driving a dynamo, magneto, engine revolution counter and wireless apparatus or other auxiliary, as :desired.

In the case of an engine of the four-stroke cycle type it can be modified to operate on a five-phase four-stroke cycle in order to provide for supercharging when required. This may be effected by providing two or more admission valves that open and close at different periods of time, one at the usual position of the crankshaft travel, the other admission valve timed to open for a relatively shorter period of time. This valve may supply air or fuel mixture for the purpose of supercharging at will. If air only is supplied it may be obtained from the same source of air pressure as for the air cooling of the engine or from a separate source of air supply.

light oil mixture in a vaporized state, during the first part of the admission stroke the fuel must be enriched when the engine runs supercharged, so that the fuel air mixture ratio may remain approximately constant. This can be effected by providing an extra fuel jet in the carburetor or by means of an additional fuel valve. A sparking plug is indicated by 58'.

There may be two or more exhaust valves, preferably two both opening and closing together.

In the case of an engine working with heavy oil fuelthat isof the compression-ignition type, excess air may be supplied to the cylinders without adversely affecting the power performance.

The engine is preferably air-cooled, an outer casing 28 of stream line form covering the cooling fins 82. The fins are provided around the body of the cylinders and are cut away at intervals as shown, for rather more than half the depth, the gaps in every other fin being opposite in plan so that a sort of labyrinth is formed for the cooling air. When under load the exhaust gases during their passage to the atmosphere drive the turbine wheels 24 and 25, one of which has for purpose the supply of the cooling air by propelling same to the engine casing 28 and thereby through the gaps and in and around passing into the atmosphere near the bottom fin.

relation thereto, means for plurality of shafts including cam-shafts connected to the elements of said engine such as valve gear, pumps and other accessories, cranks disposed upon all of these shafts, main and auxiliary frames connecting said cranks in driving operating said frames in concordance with the rotation of the crankshafts including a reduction gearing for actuating the main frame at substantially quarter engine speed, and gearing for actuating the auxiliary frames at substantially engine speed.

2. In an engine of the multi-cylinder type more particularly for aerial propulsion, a driving mechanism comprising parallel crankshafts, a plurality of shafts including cam-shafts connected to the elements of said engine such as valve gear, pumps and other accessories, crank members disposed upon tween said parallel crankshafts and the crank members of said cam-shafts and said pump shafts respectively, and auxiliary frames each having a three-point driving connection between said parallel crankshafts and the crank members of said I engine accessories, and means for frames in concordance with parallel cranks'hafts.

3. In an engine of the multi-cylinder type more particularly foraerial propulsion, a driving mechanism comprising parallel crankshafts, a plurality of shafts including cam-shafts connected tothe elements of said engine such as valve gear, pumps and other accessories, crank members disposed upon all of these shafts, a main frame having a five-point driving connection between said parallel crankshafts and the crank members of said cam-shafts and said pump shafts respectively, a reduction speed gearing between said parallel crankshafts and said main frame for actuating the main frame at substantially quarter engine speed, and auxiliary frames each having a three-point driving connection between said parallel crankshafts and the crank members ofsaid engine accessories, and gearing between saidparallel crankshafts and said auxiliary frame for actuating the auxiliary frames at substantially engine speed.

operating said the rotation of said BATEMAN DAVID SCO'I'I'.

all of these shafts, a main frame having a five-point driving connection be-

Images