US 2585029 A
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Feb. 12, 1952 NETTEL SELF-POWERED TURBOSUPERCHARGER STARTER SYSTEM FOR INTERNAL-COMBUSTION ENGINES 2 SHEETS-SI-1EET 1 Filed Oct. 25, 1947 Feb. 12, 1952 NETTEL 2,585,029
SELF-POWERED TURBOSUPERCHARGER STARTER SYSTEM FOR INTERNAL-COMBUSTION ENGINES Filed Oct. 23, 1947 2 SHEETSSHEET 2 fnlanlor:
R 3 i3 my Ia fijwgza Patented Feb. 12, 1952 UNITED STATES PATENT OFFICE SELF-POWERED TURBOSUPERCHARGER STARTER SYSTEM FOR INTERNAL- COMBUSTION ENGINES Frederick Nettel, Manhasset, N. Y.
Application October 23, 1947, Serial No. 781,726
Claims. (cm-11 This invention relates to self-powered starter systems for internal combustion engines.
One of the greatest disadvantages of reciprocating internal combustion engines lies in the necessity of employing an external auxiliary power source of considerable capacity for cranking the engines for starting.
It is common practice to use compressed air from air bottles or electric starter motors energized by storage batteries for this purpose. In smaller engines inertia starters have been employed whose flywheel was brought to high speed either by hand or by the use of a comparatively small electric motor.
It also has been proposed to employ a gas turbine for cranking the engines, said gas turbine being supplied with compressed air from an external source of supply. The compressed air, prior to admission to the turbine, was heated by burning fuel in it so as to increase its power. This gas turbine during normal operation of the engine was used to drive a supercharger blower, but was disconnected from said blower during cranking. Such arrangement did not avoid the necessity of employing an external power source of considerable capacity (in this case compressed air), in fact it was not successiul due to the large quantity of air required for cranking.
It is an object of the present invention to avoid a large and weighty source of external power for cranking.
It is a more specific object of my invention to provide for engines of the character described a self-powered starter which can be rendered operable by a small and light external source of power and is thereafter self-sustaining.
It is an additional object of my invention to provide a starter of this type which has a normal function during running of the engine whereby the same will not constitute deadweight when the engine is operating as a generator of power.
Other objects and advantages of the invention will be hereinafter pointed out or be apparent from the following description, the appended claims and the accompanying drawings which by way of non-limiting examples show various embodimentsof my invention.
Fig. 1 shows an arrangement according to my invention for a self-starting engine;
Figs. la, 1b and 1c are detail views of certain mechanisms shown schematically in Fig. 1;
Fig. 2 illustrates a modification of the invention with an auxiliary mass whose kinetic energy is utilized for crankin Figs. 2a and 2b are end and plan detail views of a reversing arrangement; and
Fig. 3 illustrates an embodiment of my invention with an electric motor energized from a, generator driven by the turbo-charger set.
My invention is particularly suited for engines working with charging sets constituting scavenging or supercharging blowers driven by gas turbine means, said charging sets being mechanically independent of the engine shaft, and under normal operating conditions being provideci with a comparatively light and small means for starting as self-powered gas turbine plants with the engine at standstill.
This is accomplished, in general, by providing a bypass conduit from the engine air delivery side of the blower to the turbine inlet. in which conduit an auxiliary combustion chamber is interposed. Rotating this set and buming fuel in said chamber will operate the supercharger set independently of the engine at high speeds, adjustable at will within a wide range by regulating the rate of combustion in said auxiliary combustion chamber.
Modern supercharger sets operate at speeds ranging from about 15,000 to 35,000 R. P. M. Though the mass of their rotors (blower and turbine wheels) is normally kept small, a very substantial kinetic energy is stored therein at the speeds mentioned. It is a further object of my invention to utilize such kinetic energy alone, and/or that of additional rotating masses actuated by the sets, for cranking the engine for starting.
It is et another object of my invention to use energy produced by self-powered turbocharger sets to crank engines at will in any direction of rotation.
It is still another object of my invention to use the kinetic energy of the self-powered supercharger sets and/or masses energized thereby, not only for cranking engines disposed to drive vehicles, but also to accelerate the vehicles from standstill.
Essentially these objects of my invention are accomplished by employing the energy of the set to turn over the engine shaft through a coupling. Such coupling, due to the fact that the engine is at standstill before cranking, must have slip characteristics either built in or inherent in its operation. Typical of such couplings are friction clutches, hydraulic clutches and electric transmissions. It is understood, of
course, that the couplings only slip during acceleration of the engine shaft and do not slip when said shaft has been brought up to a predetermined cranking speed.
Internal combustion engines of the reciprocating type require for starting certain cranking speeds by which, for the purposes of this specification. I mean speeds at which an engine starts reliably when fuel is fed to the cylinders. Minimum cranking speeds vary with the type and design of the particular engine and are generally higher for compression-ignition engines than for spark-ignition engines. These speeds are influenced by ambient air temperatures and generally have to be chosen higher if low temperature starting is contemplated.
Generally, cranking speeds within the range of from 30 to 200 R. P. M. are required. The torque during starting may be very high during the first revolution, especially at low ambient temperatures, when the bearings and piston tend to be very stiff, but falls quickly after breaking loose to values indicated by the mechanical emciency of the particular engine.
If, according to my invention, the turbocharger set is to be utilized for cranking of the engine, speed reducing means of any known type may be provided, with reduction ratios in the range of say 1:300 to 1:200, and sometimes less. It is, of course, also possible only to use the slip coupling.
A turbocharger set, when operating as an independent self-powered gas turbine power plant, requires for power equilibrium, for example at design speed, a certain gas temperature at the turbine inlet. By increasing this temperature, as for instance by burning more fuel in the auxiliary combustion chamber, the set can be made to produce excess power, which either can be used directly for cranking the engine, or which can be used to speed up the set beyond its designed speed, thereby storing excess energy as additional kinetic energy of the rotating parts of the set (blower and turbine wheels principally), which energy is used for cranking the engine.
It is within the scope of this invention to use excess energy produced by the set and the kinetic energy of rotating masses simultaneously for cranking the engine. Calculations show that such excess power, as can be furnished by turbocharger sets by increases in gas temperatures which are acceptable for modern gas turbine blades, is sufficient for cranking purposes even under very unfavorable conditions (very low ambient air temperatures).
As already mentioned, by coupling additional masses with the turbocharger set, very substantial amounts of kinetic energy may be stored in them which can be used not only to crank the engine itself, but to accelerate for example, a locomotive including a heavy train from standstill, until the engine starts operation and takes over traction. It is evident that this invention eliminates the necessity of substantial auxiliary power sources for starting, by substituting energy which is available after the turbocharger set has been started. The energy for cranking the latter, prior to starting combustion in the auxiliary combustion chamber, is very small. In many cases hand cranking might be sumcient.
Referring now in detail to the drawings, and, more particularly to Fig. 1, I have shown therein an embodiment of my invention in connection with a four-cylinder engine III, which may be 'of the compression-ignition or spark-ignition yp two or four-stroke cycle. The engine includes a usual air intake manifold M, an exhaust manifold l2, and a flywheel II! with a spur gear rim. I also provide an exhaust gas turbine driven supercharger set I! consisting of a blower I! with air intake at l6, and a turbine H with gas inlet at H and gas discharge at ll. Coupled to the turbocharger set at its upper end. as by an overrunning clutch I9, is a starting mechanism of any kind, for example an electric motor 20. The lower end of the turbocharger shaft carries a disconnectable slip coupling 2| which may be of any known type, mechanical, electrical or hydraulic, preferably with torque limiting performance. The output side of said coupling is connected to the high speed shaft of a speed reduction gear train 22. Attached to the low speed shaft of said gear train is a device 23 which when actuated will perform two operations in sequence, to wit, (1) shift a pinion 24 downwards into mesh with the gear rim of the flywheel, and (2) couple (clutch in) said pinion with the gear train 22. Alternatively the device 23 may be designed just to shift pinion 24 downwards into mesh with the gear rim of the flywheel, i. e. the clutching feature (2) being omitted and its function being taken over by the clutch 2|.
A hand lever 22' serves to operate the device 23, and electric supply cables 2| function to 0perate the clutch 2|. Obviously other known means may be used for operating these devices.
Fig. 1a shows in detail the construction of the coupling 2|, schematically indicated in Fig. 1. Said coupling comprises two mating conical type friction coupling halves 60, 8| which are fixed and slidable, respectively, on their shafts. Encircling said halves is a stationary exciter coil 02 fixed to a steel ring 63 and supported by a bracket 64. When the coil 62 is energized from the cables 2|, the axially-slidable keyed coupling half II is pulled against the fixed coupling half II to engage the conical surfaces of the halves and thus couple gear train 22 with the shaft of the turbocharger set. Normally the coupling half 8| is urged away from the half 60 by a spring 05 fixed at one end to the half SI and at the other end to a flange 66 integral with the shaft carrying the input pinion of the gear train 22.
Fig. 1b is an exe'mplitive showing in detail of the construction of the device 2!, schematically indicated in Fig. l. The input shaft of said device has secured to it one half III of a conical type friction coupling. The pinion 24 is fixed to a bushing H slidable on and keyed to the output shaft of the device 23. Said output shaft also has axially slidable thereon the second half II of the friction coupling which is arranged to be engageable with the half Ill. The bushing II and coupling half 12 are shifted along the output shaft by two levers 13, I4 pivoted in the casing of the device 23 at points I5, 16, respectively and guided at their upper ends in grooves 11, II in the casing. The levers ll, 14 are urged together by a spring 19. Between these levers is a cam ll rotatably operable by a vertical shaft II and hand lever 23'. Said cam, when the hand lever 23 first is rotated in a counterclockwise direction, serves to move lever 13 to the right, as viewed in Fig. 1b, and thereby mesh the pinion 24 with the flywheel I3. Further movement of hand lever 23' in a counterclockwise direction causes the cam to move lever I4 to the left and thus engage the two halves 10, 12, thus coupling the gear train 22 with the pinion 24.
In g- 1 t e is shown from the top,
the arrow indicating the direction of cam rotation away from idle position.
An air discharge pipe 25 runs from the blower outlet to the intake manifold I i, being connected to the same by a flap valve 26 when the latter is in its upper dotted position, and to a conduit 21 when said flap valve is in its lower dotted position. In intermediate positions, the air from the blower will flow partly to the intake manifold and partly to the conduit 21 and thence to an auxiliary external combustion chamber 28 whose discharge end is connected by a bend 29 to the engine exhaust manifold l2. Chamber 28 is provided with a fuel supply pipe 30 leading to a nozzle 30, controlled by a fuel valve 3|.
Starting of the engine may be effected as follows:
Valve 26 is moved into its lower dotted position. Clutch 2| is uncoupled. Starting motor 20 is then operated, thus starting rotation of the turbocharger set I4. An air stream thereby is created flowing from the blower air inlet I through the air blower l5 and discharge pipe 2! to conduit 21, and thence through the combustion chamber 28, bend 29, exhaust manifold l2 and gas inlet H to gas turbine l1, finally exiting to the atmosphere through outlet l8. Now fuel is fed into chamber 28 through supply pipe 30 and valve 3|. and is ignited. The hot gases formed in chamber 28 gradually begin to drive the tur-.
bine, which quickly accelerates beyond the speed of motor 20, the latter thereupon being uncoupled by clutch If! so that it can be switched off. The turbocharger set now is operating as a selfpowered gas turbine plant and can be brought up to any desired speed. To maintain this speed a certain rate of combustion in chamber 28, giving acertain gas temperature in inlet I1, is required. The pressure supplied by the blower will in this case also be at the rated value.
Now slip coupling 2| is rendered effective while at the same time the heating in chamber 28 is slightly intensified, so that the gear train 22 is driven by the set M. Then lever 23' is moved counterclockwise, thereby bringing the pinion 24 into mesh with the flywheel l3, and, thereafter, by moving lever 23' further counterclockwise, said pinion is driven by the rotating gear train 22. Simultaneously, .the heating in chamber 28 may be substantially increased, thus enabling the turbocharger set to crank the engine by driving the pinion 24 via gear train 22. If the power developed by the turbocharger is not quite adequate to overcome the breaking loose" of the engine from standstill, the kinetic energy of the set inherently is drawn upon to overcome the resistance and the speed of the set will temporaribly drop. The force available for breaking loose of the engine is determined by the slip-torque setting of clutch 2|. If, as mentioned before, the device 23 is alternatively without a clutching feature, the lever 23 first is moved counterclockwise and clutch 2| closed subsequently.
When the engine has reached a sufficient cranking speed. flap valve 25 is moved downwards somewhat, permitting air to enter the manifold M and thence be supplied to the cylinders. Fuel now is fed to the cylinders and the engine will start. Fuel to chamber 28 thereupon can be reduced, and lever 23' moved clockwise to its original position shown in Fig. 1c, thereby uncoupling pinion 24 and gear train 22 from the engine flywheel. Thereafter clutch 2| is uncoupled, bringing the gear train to rest. With increasing load on the engine the exhaust gases from the cylinders will take over the driving of the turbochargerset, so that the fuel valve ll may be closed and the chamber 28 thus put out of operation unless it is used for normal engine operation in any manner now known.
It is also possible to manage without excess heating in the chamber 28, in which case the whole power necessary for cranking will be covered by the kinetic energy stored in the rotor of the turbochar er set, resulting in a temporary speed drop of sa'i set during cranking.
It is within the scope of my invention to use a gas turbine driven blower set with unsupercharged engines for the purpose of cranking the engine for starting only. In this case the set can be put out of operation after starting the engine, or it may continue to operate without combustion chamber. In the latter case the set can help scavenge the cylinders, thereby improving engine performance.
It long has been desired to start internal combustion engines under load from standstill. This is of special importance in self-propelled vehicles and locomotives. Basically such starting is possible with the arrangement as shown in Fig. '1. However, it is often not desirable to increase the mass of rotor of the turbocharger beyond that needed for design reasons, and under heavy starting load it may not even be feasible. For such cases a modification of this invention is shown in Fig. 2 illustrating a turbocharger set and accessories suitable to replace the one shown in Fig. l.
Identical elements in these and the following figures are denoted by the same numerals. In this case the turbocharger set M drives the gear train. 22 through the slip coupling 2|. The output shaft of the gear train 22 turns a flywheel 4|! mounted to turn with a shaft 4|. This shaft is connected by hydraulic (or other slip-type) coupling 42 to a shaft 43 and meshing gears 44, 45. The gear 45 transmits power to a shaft 48, to which the pinion 24 is slidably keyed. A hand lever 41 is provided to move said pinion in or out of mesh with the engine flywheel l3.
The turbocharger is started in the same manner as described for Fig. 1 and then the flywheel 40 brought up to speed by engaging the clutch 2 I. For cranking, first the pinion 24 is meshed with the standing engine and then the coupling 42 rendered operative to transmit power, for example, by filling it with oil. It is, however, also possible after starting the turbocharger, to connect the set to the flywheel by putting coupling 2| into operation until the flywheel has reached a high speed, then to uncouple the set from the flywheel by disengaging the coupling 2|, next to mesh the pinion 24 and flywheel l3 and finally to engage the coupling 42 thereby using the kinetic energy of flywheel 40 exclusively for cranking the engine. The arrangement shown in Fig. 2 is particularly advantageous where large masses may have to be accelerated simultaneously with cranking the engine. This is the case, for example, in starting locomotives pulling heavy trains. Calculations show that comparatively small high speed flywheels suflice for this purpose.
It is sometimes desired selectively to start engines in either direction of rotation. To make this possible, according to this invention, the gears 44, 45 of Fig. 2 are replaced by a reverse gear arrangement, such as shown in Figs. 2a and 2b. For normal cranking, gears 44, 45 are in mesh, while for cranking in reverse, gears 44, 48
7 and 45' are used, gear 44 being slidably keyed to the shaft 43.
Instead of transmitting power to the flywheel by mechanical means, it is within the scope of this invention to use other type means for the same purpose, for example, (a) compressed air produced by the blower H, (b) all or part of the gases issuing from the combustion chamber 28, or (c) electrical energy produced by the turbocharger set I4.
Fig. 3 indicates another modification of this invention, as shown basically in Fig. l, but using an electrical rather than a mechanical coupling for connecting the turboblower set to the engine shaft. In said form of the invention an electric generator 54 is driven by the turbocharger set. The generator energizes an electric motor 55 for starting the engine ill by turning the driving pinion in mesh with the engine flywheel It.
It is immaterial for the purposes of this invention what type of combustion engine is to be started, i. e. whether it works on the compression-ignition or spark-ignition system, fourstroke cycle or two-stroke cycle, or what type of fuel is used (liquid or gaseous).
It is further immaterial whether or not the same or different fuels are used in the engine and auxiliary combustion chamber, respectively.
While the forms of apparatus herein described constitute preferred embodiments of the invention, it is to be understood that the invention is not limited to those forms, and that changes may be made therein without departing from the scope of the invention as defined in the appended claims.
What I claim is:
1. In combination, a reciprocating internal combustion engine, a turbocharger set consisting of gas turbine means and blower means driven by said gas turbine means, said set normally being mechanically independent of the engine shaft, conduit means connecting the delivery side of the blower means to the air intake of the engine so as to supply air to the engine, conduit means for connecting the exhaust gas outlet of the engine to the inlet of the turbine means, valve controlled conduit means for bypassing air from the delivery side of the blower means to the inlet of the turbine means, an auxiliary combustion chamber in said second named conduit means, starter means for initiating rotation of said set, means to burn fuel in said combustion chamber after initiating rotation of said set so as to operate said set, with the engine at standstill, as a self-powered gas turbine unit, and coupling means for disengageably connecting the thus operating set to the engine shaft so as to turn over the engine shaft at cranking speed for starting with energy produced by said set.
2. A combination as set forth in claim 1 wherein the coupling means includes a gear train connecting the shaft of the set to the engine shaft.
3. A combination as set forth in claim 1 wherein the coupling means includes a gear train connecting the shaft of the set to the engine shaft and wherein clutches are provided on the input and output sides of the gear train.
4. A combination as set forth in claim 1 wherein the coupling means connects the shaft of the set to the engine shaft through a rotatabiy mounted mass.
5. A combination as set forth in claim 1 wherein the coupling means connects the shaft of the set to the engine shaft through a rotatably mounted mass and wherein clutches are provided to disengageably connect said mass to the shaft of the set and to the engine shaft.
e 6. A combination as set forth in claim 1 wherein the coupling means connects the shaft of the set to the engine shaft through a rotatably mounted mass and a gear train.
7. A combination as set forth in claim 1 wherein the coupling means connects the shaft of the set to the engine shaft through a rotatably mounted mass and wherein clutches are provided to disengageably connect said gear train to the shaft of the set and the mass to the engine shaft.
8. A combination as set forth in claim 1 wherein the coupling means includes a selectively operable reversing means.
9. A combination as set forth in claim 1 wherein the coupling means connects the shaft of the set to the engine shaft through a rotatably mounted mass and wherein a selectively operable reversing means is interposed betyeen said engine and said set.
10. A combination as set forth in claim 1 wherein the coupling means comprises an electric generator driven by the set and an electric motor energized by the generator, said motor being disengageably connected to the engine FREDERICK NE'I'IEL.
REFERENCES CITED The following references are of record in the file of this patent:
UNITED STATES PATENTS .shaft.
Number Name Date 2,216,494 Kurtz et al. Oct. 1, 1940 2,435,836 Johnson Feb. 10, 1948 2,443,717 Birmann June 22, 1948 FOREIGN PATENTS Number Country Date 537,483 Great Britain June 24, 1941