Starter-generator

Abstract

The invention relates to electrical engineering, and more particularly to starter-generator devices for internal combustion engines. The technical result is achieved by optimizing and simplifying the design of a starter-generator. The present starter-generator comprises: a universal brushless DC machine and an electronic unit. The starter-generator consists of a rotor (1) and a stator (2) and is mounted directly on the engine shaft. The starter-generator is a brushless machine that is controlled by the magnitude of the back EMF, without the use of rotor position sensors. The electronic control unit (4) consists of two functional parts. One part is a control board for controlling the speed of rotation of the rotor of the brushless machine and is intended to allow the machine to operate in an engine start-up mode. The other part is a board for converting AC voltage to DC voltage and is intended to allow the brushless machine to operate as a generator. The brushless machine is switched from starter mode to generator mode by an electronic switching unit that is part of the control unit. The technical result is high starter-generator efficiency, a compact design and excellent reliability.

Description

[0001] Starter-generator

[0002] The invention relates to starter-generator devices of internal combustion engines and can be used in engine building. The described starter-generator is effectively used in aircraft building in turbojet engines. The most effective use of the starter-generator of this type is in low-power turbojet engines with a thrust of 1000 to 5000 N.

[0003] A starter-generator is known (invention certificate RU No. 2497017 C2 F02N 11 / 00).The starter-generator comprises a reversible electric machine comprising a stator connected to the engine housing, a rotor connected to the engine shaft, a casing attached to the engine housing, the rotor is made in the form of a toroidal cup having windows on the periphery separated by partitions formed by blades located on the concave surface of the cup facing the stator, part of the partitions between the windows in the cup are formed by long blades protruding into the stator, and another such part of the partitions are formed by short blades placed between the long blades, a hoop is attached to the cup surrounding the stator, and an elastic cylindrical ring made of magnetoplast is inserted into it opposite the stator, two rows of ventilation holes are made in the casing along the axis of the electric machine, separated by a conical ridge made on the inner surface of the casing opposite the rotor and protruding toward the hoop attached to the cup.

[0004] The disadvantage of this design is its complexity, the need to form air ducts that supply air to the engine housing for cooling, low reliability of the design, and relatively high weight.

[0005] A starter-generator is known (author's certificate for utility model RU No. 117167 U1 F02N 11 / 04). The starter-generator contains a valve motor-generator, which contains a stator with a winding and a rotor with permanent magnets, which is external to the stator. The stator has the ability to move forward along the axis of rotation of the rotor until it is completely extended from the rotor magnetic system.

[0006] The disadvantage of this design is the low mechanical reliability of the stator extension unit from the rotor, operation in generator mode in a limited range of rotor speeds, and the relatively large overall dimensions of the design.

[0007] A starter-generator is known (invention certificate RU No. 2321765 Cl F02N 11 / 04).The starter-generator comprises a valve-inductor machine, the rotor of which is mechanically connected to the shaft of the internal combustion engine and a position sensor, a power switch, current sensors, a "starter-generator" mode switch, and a control unit, the inputs of which are connected to the outputs of the position sensor, current sensors and the "starter-generator" mode switch, and the outputs are connected to the control inputs of the power switch, in addition, the valve-inductor machine is made two-phase, each phase contains two windings - the main and the recuperative, the beginnings of the two main windings are connected together and through the first current sensor are connected to the positive terminal of the battery, and the ends are connected to the negative terminal of the battery, the ends of the two recuperative windings are connected together and through the second current sensor are connected to the positive terminal of the battery, and the beginnings are connected to the negative terminal of the battery.

[0008] The disadvantage of this design is the use of external rotor position sensors and phase current sensors, winding of two windings on the stator, one main, the other recuperative. Such solutions increase the complexity of the design and its weight, reduce reliability and durability.

[0009] A starter-generator is known (invention certificate RU No. 2268391 C2 F02N 11 / 04) accepted as the closest analogue in terms of its features. According to the invention, the starter-generator is made on the basis of an inverted contactless electric machine. In this case, its stator is rigidly connected to the ICE housing by means of the fastening holes of the gearbox through the first structural element, which is simultaneously a holder of the crankshaft nose seal and sensitive elements of the sensors for determining information about the current rotor position. The first structural element is seated on the outer surface of the bearing, on the inner surface of which the starter-generator rotor is seated by means of the second structural element. The second structural element on the outer surface has grooves, the number of which is equal to the number of pole pairs of the electric machine, the arc length of each of them is equal to the pole division, and the edges coincide with the middle of the rotor pole.The rotor of the starter-generator is connected to the end surface of the ICE crankshaft nose and the gearbox clutch via the third structural element, while the connection of the third structural element with the end surface of the crankshaft nose is provided by fasteners with damping spacers. The disadvantage of this solution is the need to use rotor position sensors, grooves on the housing to inform the control system about the current position of the rotor, damping pads to compensate for the installation error of the starter-generator. The solutions of the existing design increase its complexity and cost, and reduce the reliability of operation.

[0010] The objectives of the proposed invention are: increasing the service life of the starter-generator, minimizing the weight and size characteristics, and reducing the cost of production.

[0011] The stated goals are achieved by: using a brushless machine with one winding, controlling the rotor position by the reverse electromotive force (EMF) of the stator winding, an electronic unit with an electronic key switching the operating mode of the brushless machine from the starter mode to the generator mode and back.

[0012] The essence of the invention is explained by the drawing of the starter-generator Fig. 1. The starter-generator consists of an external rotor with permanent magnets 1, a stator with a magnetic circuit and a winding attached to the housing of the internal combustion engine 2, a bearing unit used to attach a brushless motor to the shaft of the internal combustion engine 3, an electronic control unit 4 combining three functions: switching electrical circuits, controlling the rotation of the rotor, converting the generator voltage from alternating to direct.

[0013] The starter-generator operates as follows. The control unit 4 supplies voltage to the stator winding. The stator winding is three-phase. The control unit monitors the rotor speed by the induced current created by the reverse electromotive force in the winding, on which there is no external voltage at this moment, additional use of rotor position sensors is not required. The alternating magnetic field of the stator interacts with the magnetic field of the permanent magnets to create a torque on the rotor 1. The rotor sets in motion the ICE shaft to which it is fixedly connected. The stator is positioned relative to the ICE shaft using the bearing unit 3 and is fixedly mounted on the ICE body through the provided mounting holes.When the ICE rotor shaft reaches idle speed, the electronic switch of the control unit 4 switches off the speed control module and connects the board for converting voltage from alternating three-phase to direct single-phase to the terminals of the brushless machine winding, the brushless machine operates in the generator mode. Thus, the proposed technical solution for a starter-generator in an ICE with a relatively simple design allows for a compact design with high specific power due to the use of a brushless machine with one winding used both in the starter mode and in the generator mode, to increase the reliability of the design by abandoning the rotor position sensors, the absence of movable contacts of the brushless machine rotor and the ICE shaft will significantly extend the service life of the starter-generator. At the same time, the simplicity of the starter-generator design will allow its wide use in technology.

Claims

5 Invention formula A starter-generator comprising a universal brushless DC machine with an electronic unit installed in the housing of an internal combustion engine, including a stator secured to the engine housing, including a housing, a magnetic circuit with a winding, a rotor installed on the drive shaft of the engine, including a housing and permanent magnets, an electronic unit installed on the engine housing, including a board for controlling the rotation speed of the brushless machine operating in the starter mode, a board for converting the voltage generated by the brushless machine in the generator mode, an electronic switching unit, characterized in that the brushless machine does not contain rotor position sensors, wherein the winding of the machine operates both in the starter mode and in the generator mode, the electronic control unit combines three functions: switching electrical circuits, controlling the rotation of the rotor, converting the generator voltage from alternating to direct.

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