US3390670A - Combined engines - Google Patents

Description

W. A. BRICE COMBINED ENGINES July 2, 1968 3 Sheets-Sheet 1 Filed June 26, 1967 Fi|:|.- Z

INVENTOR. WILL/AM A. BRICE ATTORNZ') July 2, 1968 Filed June 26. 1967 5 Sheets-Sheet 2 uoo I58 453 f/ I 8 I56 I57 I! {55 I50 INVENTOR.

WILLIAM A. BRICE ATTORNEY July 2, 1968 w. A. BRICE 3,390,670

COMBINED ENGINES Filed June 26, 1967 I5 Sheets-Sheet 3 fi Jo INVENTOR. 5' WILLIAM A. BRICE BY my; I0 \41 '08I49 no M ATTORNEY United States Patent 3,390,670 COMBINED ENGINES William A. Brice, Beliilower, Califl, assignor to Ametek, Inc., New York, N.Y., a corporation of Delaware Continuation-impart of application Ser. No. 495,980, Oct. 14, 1965. This application June 26, 1967, Ser. No..648,579

9 Claims. (Cl. 123-497) ABSTRACT OF THE DISCLGSURE The invention comprises a combination of two or more two cycle internal combustion engines in a single multicylinder engine. The crankcase compression of the air-fuel mixture for injection into the individual engines is achieved by use of valve means between the carburator and crankcase to permit the power stroke of the engines to compress the air-fuel mixture for injection into the motor cylinders. Preferably, separate valve means are provided for each engine. The separate engines are mounted onto a block having a single output shaft geared to the crankshafts of the individual engines. A fuel supply manifold of balanced construction, i.e., of equal flow resistance is provided to the intakes of each engine. The engines are geared to the output shaft to provide a timed relationship between their respective cycles and thus assure a smooth and continuous delivery of power during operation.

Description of the invention This application is a continuation-in-part of copending application Ser. No. 495,980 filed Oct. 14, 1965, now Patent No. 3,370,429.

The invention relates to multicylinder engines that are particularly useful in model craft or for any application requiring a high power to weight ratio, and particularly of value for fractional horsepower engines.

In these applications, two cycle engines are almost universally used and these engines have means to confine the air-fuel mixture beneath the piston, so that the power stroke compresses the air-fuel mixture for injection into the cylinder when the piston reaches the bottom of the power stroke. Some multicylinder engines use separate fuel compression pistons, but this design is hindered by the greater complexity and weight of the engines. Because of the need for a simple air-fuel mixture injection there have not been any successful efforts to the development of a multicylinder two cycle engine, but instead, the larger size engines have simply been scaled up versions of the smaller single cylinder engine. Scaled up versions, however, often distort the bulk of the engine and prevent faithful scaling of model aircraft, cars or boats since the large, single cylinder usually protrudes past the outside surface of the model. The scaled up versions of small cylinder engines also fail to provide a smooth delivery of power during the cycle of the engine and require the use of relatively large flywheels to compress the air-fuel mixture during the compression stroke of the engine.

My invention comprises a means for interconnecting several small two cycle engines into a very compact and light weight assembly having a single output power shaft journalled in the interconnecting means and connected to the crankshaft of each of the engines in a timing-firing relationship to provide a balanced firing relationship of the individual engines. The interconnecting means is entirely compatible with the individual engines which can be quickly mounted and demounted on the assembly to permit the rapid replacement of any malfunctioning engine. The power plant also includes a single carburator including connections of equal length and of equal cross 3,39%,670 Patented July 2, 1968 sectional area to the intake of each engine. Valve means are interposed between the carburator and the engine crankcases to confine the air-fuel mixture beneath the pistons to thereby permit crankcase compression of the airfuel mixture Preferably, separate valves for each engine are provided to secure maximum compression of the mixture and to permit simultaneous firing. The resulting engine is very compact and can be concealed in the airfoil of most craft or can be exposed to simulate the multicylinder radial engines of full scale craft. Surprisingly, I have found that the combined engines develop an average of about 26 percent more power than does a single cylinder engine of the same design having the same displacement as the sum of the displacements of the multiple engines.

My invention will now be described by reference to the figures of which:

FIGURE 1 is a front view of a three cylinder assemy;

FIGURE 2 is a view along lines 2-2 of FIGURE 1 with only one of the engines in cross section;

FIGURE 3 is a front view of a two cylinder assembly;

FIGURE 4 is a sectional view of the block and cap mount used in the two cylinder assembly;

FIGURE 5 is a view along line 5-5 of FIGURE 4;

FIGURE 6 is a view of a four cylinder assembly;

FIGURE 7 is a view of the block used in the four cylinder assembly;

FiGURE 8 is a view along line 8-8 of FIGURE 7;

FIGURE 9 illustrates an engine with an alternative fuel supply system; and

FIGURE 10 is an illustration of a tandem construction of two assemblies such as those of FIGURES 3-5.

Referring now to FIGURE 1 there is shown a three cylinder assembly having engines 10, 12 and 14 symmetrically disposed about a central power shaft. The engines are preferably of equal displacement and design. The engines are air-cooled with radial fins, not shown surrounding the upper end of the cylinder. These engines are standard and readily available two cycle engines that use glow plugs 20 for ignition of the fuel although of course spark ignition could also be used. The engines are mounted on a block described in greater detail in FIGURE 2 which has flanges 22 at the rear of the assembly for mounting the assembly to the craft. The carburators of the engines have been removed and a new carburator with a needle valve adjustment 28 is provided. The carburator has air intake 24 and a boss 26 for connection of the fuel supply line. The flow passageway for the air-fuel mixture is shown in the hidden object lines of FIGURE 1 as a bore 30 which intersects a radial groove 32 in the mounting block. The groove 32 intersects radially disposed bores 34 in the block through which the crankshaft sleeve and intake of the individual engines extend.

FIGURE 2 is a view of the assembly in greater detail. This view shows the assembly in cross section with the engine on the right side also in cross section. The individual engines 12 and 14 are mounted in a block and cap assembly comprising block 40 having a peripheral lip 42 into which is fitted shoulder 37 of cap 36. Screws 38 engage threaded taps in block 40 to secure cap 36 to the block. The power shaft 16 entends between bearing 44 mounted in a central bore in block 40 and bearing 46 mounted in a bore in boss 48 of cap 36. The rear of shaft 16 supports gear 50 and washer 52 is provided to retain bearing 48 in its recess.

Motor 14 is shown mounted in bore 34 of block 40 with its crankshaft sleeve 54 extending past shoulder 56 formed between bore 34 and counterbore 58. This shoulder provides the means for retention of the motor in the assembly since spanner nut 60 which is an element of the model engines as purchased is turned onto the threaded end of sleeve 54 and bears against washer 62. Shoulder 64 on the face of the crankcase of motor 14 fits into bore 34 and also aids in securing the motor to block 40. In this manner, bore 34 is sealed to the atmosphere and comprises a fuel-air chamber for sup ly to the engines.

Gear 66 that meshes with gear 50 is secured to the crankshaft of motor 14 by Washer 68 and cap screw 70. The driving gears such as 66 are connected to the driven gear 50 on the power shaft in a timed relationship so that the engines sequentially fire in rotational order, e.g., followed by 12, followed by 14. This order of firing insures smoothness of operation at high and low speeds as normally provided on internal combustion engines of the same number of cylinders. In the three cylinder engine, each cycle has an angular relationship of 120 degrees behind the engine with the immediately preceding cycle. l

Eigine 12 is shown in cross section in FIGURE 2 as comprising a block 72 bored to provide a crankcase and closed with threaded cap 76. The motor cylinder 78 is threaded into the block 72 and has cap 74. Crankcase sleeve 80 extends from the front of block 72. Piston 82 is connnected with rod 84 to pin 86 on the flywheel.

The valve means between the carburator and crankcase is shown as the preferred construction with separate valves for each engine. These valves are formed by the crankshaft and sleeve as is common for engines of this type which have the flywheel and the crankshaft as a single unit with a bore 90 that extends through the shaft to form the fuel pasageway into the crankcase. The airfuel mixture from the carburator enters bore 90 in the shaft through port 92 when that port is aligned with the slotted opening 94 in sleeve 80. This occurs when the piston is from 32.5 degrees from bottom dead center and the port remains open until the piston is 47.5 degrees past top dead center. The reduced pressure in the crankcase draws the fuel mixture into the crankcase from chamber 34. In the position shown, port 92 is sealed against the wall of sleeve 80 and the air-fuel mixture is compressed and injected into the cylinder 78 through port 96 which is a groove in the lower half of the cylinder wall and which is uncovered when the piston reaches the bottom of its stroke.

The air-fuel mixture is supplied to slots 94 of the individual engines through the radial groove 32 that intersects bores 34 and that communicates with bore from the carburator 18. This groove 32 is formed by boring block 40 at 98 and then cutting an offset groove 32. A cap 99 is used to close bore 98.

Referring now to FIGURE 3, a twin engine is shown with engines 100 and 102 mounted on a block having a cap 104 secured with screws 106 and having rear flanges 108 for mounting of the assembly. A unit of this construction using two engines of 0.15 cubic inch displacement has consistently developed 0.62 brake horsepower. The power shaft 110 from the unit extends through cap 104. The carburator 112 has needle valve adjustment 114, air inlet 116 and fuel inlet 118. The carburator seats in a bored recess 120 in boss 122 of the block. A bore 124 extends into the block and intersects transverse bore 126 which together form the flow passageway for the air fuel mixture to bores 128 in the block.

FIGURE 4 shows the assembly in cross section at line 44' with the engines removed for illustration. This block has rear legs 127 that extend past the engines 102 and 100 and support flanges 108. The front face of block 101 has a peripheral lip 140 which engages a shoulder 138 of cap 104. This cap has a central boss 129 which is bored at 130 to receive bearing race 131. Block 101 has a similar bore centrally located to receive bearing race 132. Extending between these bearings is the power shaft 110 with washers 133 and 134 to retain the bearings in place. Gear 136 is mounted on shaft and engages the driving gears of the individual motors.

FIGURE 5 shows motors 100 and 102 with their crankshaft sleeves 158 extending into bores 128 of block 140. Bores 128 are counterbored at to provide shoulder 156 that provides a seat for washer 157 and spanner nut 155 which is threaded on the end of sleeve 158. The gears 150 are secured to their crankshafts by cap screws 154 and washers 153.

Although separate valves for the crankcase sealing are used for each engine and these are of the type illustrated in engine 12, FIGURE 2, the twin assembly can use simultaneous firing. A single valve such as a conventional reed valve could be located in bore 124 of the fuel-air mixture manifold and both crankcases could be vented into this manifold by providing a port through the crankcase faces flanged against the face of bores 128. In this construction, bores 134 and 126 should be sized at their minimum value to maintain sufficient compression, e.g., their volume should not exceed about 1015 percent of the total crankcase volumes of the two engines.

FIGURE 6 shows a four engine assembly of my invention having engines, three of which are shown as 162, 164 and 166 mounted on block 168 having legs 170 extending between the engines with dependent flanges 172 for attachment of the assembly to a model. A unit of this construction using four engines of 0.15 cubic inch displacement has consistently developed 1.2 brake horsepower. The carburator 174 has air intake 176 and boss for connection to a fuel line. Cap 178 is attached to block 168 with screws 180 which engage threaded taps in the block 170 and which are provided with lock washers 182. The engines are retained in block 170 using spanner nuts as described in the previous assemblies. The power shaft and the individual gear drives from the engines are similar 01: those previously discussed. In the assembly, the engines are placed in a timed relationship in the engagement of their drive gears with the power shaft gear to provide a clockwise or counterclockwise rotational sequence of firing of the engines, thereby producing a smooth and continuous delivery of power to shaft 184.

FIGURE 7 shows the front of block 168. The threaded taps 181 are provided for screws 180', previously mentioned. The central bores 194 and 1% provide a circular seat for the rear bearing race of the power shaft similar to that described for the two and three cylinder assemblies. These bores and the bores for the mounting of the engines can also be seen in FIGURE 8 'which is a view along line 88'. The engines are mounted in the four bored seats symmetrically disposed about the face of the block 168. The engine seats are formed by bore and counter bores 191 and 192 which provide a circular seat or flange for engagement by the spanner nut attached to the threaded end of the crankshaft sleeves of the engines in the manner previously discussed. The fuel supply manifold which provides equal flow resistance to each of the four engines and thereby assures equal performance by these engines comprises bore 198 that extends from the seat 199' for the carburator at the periphery of block 168 and intersects bore 201 shown in FIGURE 8 to be centrally cut into the rear face of block 168. A radial groove 197 is cut into the block as shown and this groove intersects the four bores 192 in block 168 to provide a passageway for fuel and air from the carburator through bore 198, bore 201 and groove 197 to the intakes of the engines which are in their crankcase sleeves that are mounted in bores 192. Bore 201 is closed with cap 202. The fuel distribution system thus described is symmetrical, i.e., of equal length and equal cross sectional area to each engine and provides a uniform supply of fuel to each of the engines.

The power plant illustrated by FIGURE 9 has a generally indicated chamber 210 defined by a back wall 211 to which the cylindrical flange 212 of the front wall 213 is secured. The back wall 211 has a bore 211A in axial alignment with a bore 213A in the front wall. Bearing units 214 are located in the bores 211A and 213A in support of the shaft 215. A gear 216 is splined to the shaft 215 within the chamber 210. A propeller 217 is shown as clamped against a support 218 fast on the shaft by a head 219 anchored by a screw 220 threaded axially into the shaft 215. 1

Internal combustion engines are indicated at 221. These are of the single cylinder, two stroke, two cycle type previously discussed except for the fuel supply means. The base 221B of each engine 221 is shown as approximately cube-shaped and is secured to the rear face of the rear chamber wall 211. There are four engines 221 and these are arranged in oppositely disposed pairs with the cylinders of each pair abutting in a side-by-side relationship and all with their axes in a common plane transverse with respect to the axis of shaft 215. Each such engines also has a crankshaft 221C extending forwardly through its individual crankcase and through the chamber wall 211 into chamber 210 where each has a gear 222 anchored thereto in mesh with the gear 216. Each gear 222 is set in mesh with the gear 216 so that the angular relationship of the crankshafts is that normal for an internal combustion engine of the same type but having four cylinders, i.e., the individual engines have their own cycle of firing which precedes the next engines cycle by a predetermined angle, e.g., 90 degrees.

The power plant has a carburator 123 connected to the air-fuel intake of each engine located in the crankcase wall with an adjustable valve 224 for regulating the mixture of air and fuel, the former entering through the air intake 225 and the latter through the fuel inlet 226 when connected to a fuel tank, not shown. The airfuel mixture enters the crankcase of the engine through a reed valve not shown which has a thin, resilient flapper or reed in the flow passageway and which deflects inwardly so as to admit the mixture when the piston is on its compression stroke and which seals the crankcase when the piston is on the power stroke and is compressing the mixture confined in the crankcase.

FIGURE shows two twin engine assemblies connected in tandem to provide a four cylinder engine. The twin units are essentially the same as described in regard to FIGURES 3-5 except power shafts 110 and 110A extend through bores 145 and 145A and are interlocked by the keyed sleeve 147 having set screws 149. The two units are bolted together, back to back, through feet 108 and 108A. The cap of the right hand unit is replaced with a base 149 having mounting flange 151. The two pairs of engines used are counter-rotating, i.e., the two engines on block 140 are counter-rotating to the two engines on block 140A. This is simply achieved by using crankshafts in the engines on block 140 with fuel inlet ports such as 92 shown in FIGURE 2 but which are retarded 90 degrees from the ports in the engine crankshafts used on block 140A.'

The invention as thus described comprises a mounting block and cap assembly for the geared interconnection of two or more two cycle engines to a single power output shaft. The crankcase compression of the fuel supply to the engines is preserved by the means for mounting the engines with their individual crankcase. The fuel supply provides a common manifold to the engines with equally sized flow paths to each of the engines. The engines are assembled on the mounting block with their crankshafts geared to the power shaft in a timed relationship to provide 'a balanced and even delivery of power.

The separate engines with their own individual crankcases have a particular advantage for the fractional horsepower engines used in model craft since multicylinder crankshafts require a split bearing block attachment between the connecting rods and the crankshaft. This construction requires extremely precise machining and the assembly of the engines is complex so that reliable performance is not readily achieved in the small scale engines.

The use of engines with individual crankcases is essential for assemblies having sequential firing order since the crankcases serve as the fuel compression chamber and are, therefore, integral parts of each engines fuel supply system. A single valve for two or more engines firing simultaneously can be used as mentioned provided that the fuel manifold chamber is sized sufficiently small with respect to the total crankcase volume so that adequate compression for injection of the fuel-air mixture can be achieved. Even with assemblies having the engines timed for simultaneous'firing, it is preferred to use individual crankcases with their separate fuel crankcase valves because each crankcase is sized to the optimum volume necessary to achieve the proper compression of the air-fuel mixture for injection into the cylinder. Permitting the chambers to vent into a common manifold will tend to increase this volume and reduce the compression of the fuel mixture.

While the invention has been described by reference to specific embodiments, these have been supplied to illustrate the preferred form of the invention. It is not intended that the illustrated embodiments be unduly limiting of the invention, but rather, that the invention be defined by the means and their obvious equivalents set forth in the following claims.

I claim:

1. A mount for the detachable assembly of a plurality of two-cycle, single cylinder internal combustion engines having air-fuel intake means in their crankcase sleeves which comprises: a block carrying power shaft bearing means, engine mounting means comprising bores peripherally disposed about said bearing means to receive the crankcase sleeves of said engines, carburetor mounting means carried on said block, flow passageways through said block between said carburetor and said engine mounting means to provide equal flow resistance from said carburetor mounting means to a point adjacent the air-fuel intake means of said engines when mounted in said bores.

2. The mount of claim 1 in combination with a cap removably attached to said block, a power shaft journalled in said cap and extending to said shaft bearing means.

3. The mount of claim 1 in combination with a carburetor mounted to discharge an air-fuel mixture into said How passageways.

4. The mount of claim 1 wherein said flow passageways comprise a bored recess centrally positioned on one face of said block which intersects said peripherally disposed engine mounting means.

5. The mount of claim 1 wherein said passageways comprise a longitudinal bore through said block which intersects said engine mounting means.

6. A power plant comprising an assembly of: a mounting block carrying power shaft bearing means, a cap removably secured to said block, a power shaft journalled in said cap and extending to said shaft bearing means on said block, a plurality of internal combustion engines of the two cycle type having air-fuel mixture intake ports in their crankshaft sleeves mounted on said block with their crankshaft sleeves in bores traversing said block and radially positioned about said shaft bearing means, means to retain said engines on said block, means interconnecting the separate crankshafts of said engines to said power shaft in a timing-driving relationship, carburetor means carried on said block and air-fuel mixture flow passageways of equal flow resistance extending from said carburetor through said block to the intake ports of each of said engines.

7. The power plant of claim 6 wherein said engines have threaded crankshaft sleeves and are retained on said block by means cooperative with said threaded sleeves.

8. The power plant of claim 6 comprising two engines in opposed assembly and timed to fire simultaneously.

9. The power plant of claim 6 comprising at least three 7 8 engines radially spaced on said interconnecting means and 868,497 10/ 1907 Smith. timed to fire in a sequential order at equal angular incre- 2,229,836 1/ 1941 Bracke \et al.

mental degrees of rotation of said power output shaft.

FOREIGN PATENTS References 5 689,675 4/1953 Great Britain. UNITED STATES PATENTS 1,282,262 12/1961 France.

846,004 3/1907 Brooks.

1,466,394 8/1923 Fornaca. WENDELL E. BURNS, Primary Examiner.

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