GB2139430A

GB2139430A - Electric machine coupled to I.C. engine

Info

Publication number: GB2139430A
Application number: GB08407406A
Authority: GB
Inventors: Marcello Montali
Original assignee: Fiat Veicoli Industriali SpA
Current assignee: Fiat Veicoli Industriali SpA
Priority date: 1983-05-04
Filing date: 1984-03-22
Publication date: 1984-11-07
Also published as: DE3408211A1; FR2546344A1; FR2542859A1; GB8407406D0; FR2546344B1; IT8353281V0

Abstract

An electrical machine coupleable to an internal combustion engine (1) particularly a reciprocating internal combustion engine, has the rotor of the electrical machine fixed directly to the output end of the engine crankshaft facing the motor vehicle clutch. The rotor constitutes a flywheel mass (4b) carrying a toroidal electric winding (6) disposed in a peripheral annular slot in the flywheel mass. The body of I.C. engine carries in a position facing the rotor a winding (8) which is provided with pole pieces and forms the stator of the electral machine. <IMAGE>

Description

SPECIFICATION Electric machine for coupling to an internal combustion engine The invention relates to an electric machine for coupling to an internal combustion engine.

Often with internal combustion engines, e.g.

reciprocating l.C. motor vehicle engines, it is necessary to use part of the mechanical power available at the engine output shaft to generate electrical energy for feeding various services required for proper operation of the motor vehicle.

Thus it is desirable to optimise the devices which enable such power take-off and conversion, such that they are both simple and able to feed all the various desired services.

To this end, the invention provides an electric machine for coupling to an internal combustion engine, wherein a rotor of the electric machine is coupleable directly to the output end of an output shaft of the engine, said rotor comprising a flywheel mass with a toroidal electric winding located in an annular slot provided therein, and wherein a winding with pole pieces is housable in a fixed structure associated with the engine and locatable to radially face said rotor and form a stator of the electric machine.

An electric machine embodying the invention is of small overall size as its rotor is used substantially as a flywheel mass and its stator as a flywheel housing.

Such an electric machine is particularly useful in a motor vehicle, when the rotor would be fixed directly between the end of the motor vehicle output shaft and the motor vehicle clutch.

When used with a reciprocating l.C. engine the rotor would be coupled to the crankshaft of the engine.

According to a preferred arrangement the system provides means enabling the electric machine to operate as an A.C. electrical generator, and means enabling the electric machine to operate as D.C. electrical motor.

The generated A.C. electricity may be used for various purposes, e.g. recharging the motor vehicle batteries and, in the case of industrial vehicles, for generating braking power or for feeding electrical power outlets.

If the electric machine is fed with direct current from the batteries, to operate as a D.C. electrical motor, the electric machine rotates the crankshaft or other engine output shaft, thus enabling starting of the engine. This application of the electric machine is particularly useful in the case of vehicles with a reciprocating diesel engine supercharged by means of turbocompression. The compression ratios in such cases must be such as to produce spontaneous fuel ignition. As, when starting, the engine is cold and compression losses due to seepage are high due to the relative slowness of crankshaft rotation, the engine has to be designed with a compression ratio which is relatively high, leading to a loss of deliverable power.With an electric machine as now proposed it is possible to increase the rotational speed of the crankshaft during starting and consequently reduce the compression ratio, thus increasing the power which may be delivered by the engine if other conditions r emain equal, in that the turboblower is able to increase the feed pressure.

Other advantages of the present invention will become apparent from the following description of a machine embodying the invention, made with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic part sectional view of a known engine and; Figure 2 is a similar, partial, view of an engine embodying the invention.

The two figures show a motor vehicle reciprocating internal combustion 1 which includes a fixed structure 2 in which one end of the engine crankshaft 3 isjournalled for rotation.

The output end 3a of crankshaft 3 has a flywheel mass affixed to it.

Figure 1 shows the conventional engine arrangement with a flywheel mass 4a, whilst figure 2 shows a flywheel mass 4b embodying the invention. With both arrangements that surface of the flywheel spaced from the engine 1 is provided an annular seat 4c against which the motor vehicle clutch (not shown) bears in a known way.

The flywheel 4b embodying the invention is provided with an annular, peripheral, slot 5 as shown. In slot 5 a closed, toroidal, electric winding is formed by a wire wound continuously on a toroidal support ring without inlet or outlet terminals; so as to form a Pacinotti ring. The fixed structure 2 of engine 1 is provided with a ringshaped extension 7, as shown, and a fixed winding 8, having pole pieces, is located in an annular cavity in the extension 7 in a position facing winding 6. Consequently the winding 6 forms a rotor of an electrical machine, the stator of which is constituted by the fixed winding 8.

The electrical machine may operate either as an A.C. electrical generator or as a D.C. electrical motor according to the manner in which it is arranged.

To operate the machine as an A.C. electrical generator it is necessary to provide two rings rigidly fixed to the rotor and permanently connected to the same two turns or groups of turns disposed in radially opposing positions, electrical energy being withdrawn via two contacts rigidly affixed to the fixed structure 2 (or extension 7) and sliding on said rings.

To operate the machine as a D.C. electrical motor it is necessary to provide a strip-type commutator, (each strip being connected to one rotor turn), and two fixed brushes carried by the engine fixed structure 2 and sliding on the commutator in radially opposing positions. The fixed brushes may be supported on the engine fixed structure 2 by means which enable them to assume two different positions: in a first position the brushes being in sliding contact with the commutator (the brushes would be disposed in this position when the electric machine is to be used as a D.C. motor); and in a second position the brushes being separated from the commutator (the brushes being disposed in this position when the electric machine is not in use as a D.C. motor), to enable prevention of too rapid wearing of the brushes when not in use.

As a D.C. electrical motor, the electric machine is particularly useful for diesel engines.

By way of example, it will be assumed that the engine shown in the figures is a diesel engine with a piston displacement of 9.5 litres, a compression ratio of 15.5, a maximum effective mean pressure of 11.3 bars and a maximum power of 176 kW at 2300 r.p.m., when supercharged by turbocompression. On using an electric motor embodying the invention as a D.C. electrical motor, the engine crankshaft 3 may be rotated at up to approximately 600 r.p.m. during starting. At this speed air seepage decreases, so that the final starting pressure necessary is reached at a reduced compression ratio 10.9:1 instead of 15.5:1 as found with known engines.If the pressure and the temperature at the end of combustion are kept constant, the density of the feed air may be increased, in the case under consideration, to the extent of attaining an increase in the effective mean pressure of more than 40% over the preceding case. An overall power of 250 kW can therefore be delivered.

Because of the high supercharging levels possible with this type of coupling'between an electric machine and a diesel engine supercharged by turbo-compression, the use of hot gas for a second expansion in a turbine which returns energy to the crankshaft, i.e. the TURBO COMPOUND becomes increasingly possible.

Furthermore, in the case of vehicles which provided door-to-door service with frequent braking and acceleration requirements, the braking energy stored in the batteries may be used for accelerating the vehicle during its starting, thus making use of the braking energy.

It will be appreciated that although specifically described with reference to its use with reciprocating motor vehicle engines, the electric machine of the present invention may be used with advantage coupled to the output shaft of other forms of engine, e.g. rotary engines, and may be used other than in motor vehicles.

It is apparent that the dimensions may be changed and other modifications may be made, without departing from the scope of the present invention.

Claims

1. An electric machine for coupling to an internal combustion engine, wherein z rotor of the electric machine is coupleable directly to the output end of an output shaft of the engine, said rotor comprising a flywheel mass with a toroidal electric winding located in an annular compartment provided therein, and wherein a winding with pole pieces is housable in a fixed structure associated with the engine and locatable to radially face said rotor and form a stator of the electric machine.

2. An electric machine as claimed in claim 1 for use in a motor vehicle, wherein the rotor is fixabie directly to the output shaft of the motor vehicle engine between this the end thereof and the motor vehicle clutch.

3. An electric machine as claimed in claim 1 or claim 2 for use with a reciprocating internal combustion engine, wherein the rotor is fixable directly to the output end of the engine crankshaft.

4. A machine as claimed in any one of claims 1 to 3, wherein means are provided enabling the machine to operate as a D.C. electrical motor.

5. A machine as claimed in any one of claims 1 to 4 wherein means are provided enabling the machine to operate as an A.C. electrical generator.

6. An electrical machine as claimed in claim 1 and substantially as herein described with reference to Figure 2 of the accompanying drawings.

7. An internal combustion engine, including an electric machine as claimed in any one of the preceding claims.