Data processing: vehicles – navigation – and relative location – Vehicle control – guidance – operation – or indication – With indicator or control of power plant
Reexamination Certificate
2001-12-06
2004-08-17
Wolfe, Willis R. (Department: 3747)
Data processing: vehicles, navigation, and relative location
Vehicle control, guidance, operation, or indication
With indicator or control of power plant
C073S118040, C123S179200, C123S406180, C123S406580
Reexamination Certificate
active
06778899
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a process for determining the crankshaft angle in an engine having a crankshaft which is nonrototably connected to the rotor of an electric machine, to a control unit for determining the crankshaft angle of the engine, to a memory unit, to a computer program product, and to a drive train.
2. Description of the Related Art
Many different types of engines are known. For example, engines are used in vehicles, where they are usually designed as internal combustion engines. An electric machine, for example, can be connected to the engine. This electric machine can be a rotating machine, which, with the help of a magnetic field, converts electrical energy into mechanical energy when operating according to the motor principle or mechanical energy into electrical energy when operating according to the generator principle. An electric machine of this type can therefore function as a so-called starter-generator. A starter-generator is, for example, a permanent-magnet, synchronous machine, which can be installed between the crankshaft of the engine and the following components of the drive train. The starter-generator makes it possible to start the engine. In addition, it can also function as a generator during the operation of the vehicle and can therefore replace both the starter and the generator in the vehicle. Depending on the operating state of the electric machine, it is therefore possible for motor torque and/or generator torque to be produced.
Rotating fields occur in the electric machine. If the rotor rotates at the same speed as the rotating field of the stator, we call the machine a synchronous machine. If the rotor rotates more slowly or faster than the rotating field of the stator, we call the machine an asynchronous machine.
These types of electric machines usually have a device for determining the angular position of the rotor with respect to the stator. So that electric machines can be operated under optimum conditions, it is necessary for the angular position of the rotor to be known. One of the reasons for this is that electric machines usually require a static converter, so that they can obtain a three-phase feed from an intermediate circuit voltage. To generate the optimum torque it for the electric machine, the three-phase current must be impressed in such a way that the maximum torque can develop. For this purpose, the static converter must know the exact position of the rotor at all times. The ability to detect the position of the rotor with high precision is therefore the prerequisite for the operation of an electric machine at high efficiency.
When the engine is designed as an internal combustion engine for use in a motor vehicle, for example, the engine control unit must know the crankshaft angle and the camshaft angle when it starts the internal combustion engine. These values are important, because they are used, for example, to determine the ignition sequence, the ignition timing, and similar values. In the past, when an internal combustion engine is started, first the top dead centers (TDC) of the crankshaft and of the camshaft are detected as the crankshaft is rotated around an angle of 720°. This is also called the “learning phase”. Only after the learning phase has been completed is it possible for the ignition of the internal combustion engine to start. So that the learning process can be accomplished in optimum fashion, the crankshaft must therefore first perform two complete revolutions, and from these two first crankshaft revolutions, the crankshaft position and the camshaft position, that is, the corresponding top dead centers, are then determined.
Solutions are also known for generating corresponding crankshaft signals and camshaft signals in discrete form. The scanning process according to the tooth/gap method could be mentioned here by way of example, which is carried out with so-called 60-2 toothed rings. This is a commonly used, well-known process.
The solutions known so far, however, suffer from a number of disadvantages. For example, long starting times are required, because two complete revolutions of the crankshaft must be completed first. This also means, however, that it is impossible for the engine to operate in any reasonable manner on a start-stop basis. Under conditions of start-stop operation, the internal combustion engine is turned off briefly when the vehicle comes to a stop, such as when stopping for a red light, and then is started again automatically when the vehicle is ready to start moving again.
In addition, very slow rotational speeds cannot be detected by the known solutions. This is especially true when the known tooth/gap scanning methods are used. In addition, the known solutions can be used reasonably only down to a certain lower rpm limit. Operation at very low rpm's of the internal combustion engine, such as in the range of an idling engine or in the situation that the engine has actually come to a complete stop, has not been possible so far.
SUMMARY OF THE INVENTION
The disadvantages described above in conjunction with the state of the art can be avoided. In addition, an improved control unit, an improved memory unit, an improved computer program product, and an improved drive train are also to be provided.
Features and details which are described in conjunction with the process according to the invention also apply to the control unit according to the invention and to the drive train according to the invention, and vice versa in each case. The same is also true for the memory unit according to the invention and the computer program product according to the invention.
According to the first aspect of the invention, the crankshaft angle of an engine is determined, where the engine is connected to an electric machine, functioning especially as a starter-generator, wherein the rotor of the electric machine is connected nonrotatably to the crankshaft, where the electric machine has a control unit for controlling the electric machine, and the electric machine has a device for determining the angular position of the rotor with respect to the stator. The process according to the invention includes the following steps:
(a) the current angular position of the rotor is detected by the device for determining the angular position, and this information is transmitted to the control unit;
(b) the detected angle values are used in the control unit to determine the corresponding, current crankshaft angle;
(c) the crankshaft angle determined in this way is transmitted from the control unit to the control unit of the engine; and
(d) the detected angle values of the rotor and/or the crankshaft angles determined from those values are stored at least temporarily in a memory unit.
As a result of the process according to the invention, the disadvantages associated with the state of the art described above can be avoided. In particular, the process according to the invention can be used to start the engine quickly.
A basic idea of the present invention is that the electric machine connected to the engine is already equipped in most cases with a high-resolution rotational angle detector. These position signals are evaluated by the control unit of the electric machine. Because the rotor of the electric machine is connected nonrotatably to the crankshaft of the engine, it is possible to use these rotor angle values to determine the current crankshaft angle also. A top dead center signal, for example, can be generated by a single signal formed over a crankshaft angle of 360°, so that the previously required, tedious learning process extending over two complete revolutions of the crankshaft can be eliminated. In addition, there is the possibility of omitting the previously conventional and necessary crankshaft angle signal sensors.
As a result, the number of parts required for the engine can be reduced, which leads to cost savings. The angle values of the rotor, furthermore, can be detected very precisely, so that the process also functions reliably ev
Kramer Markus
Weimer Jürgen
Cohen & Pontani, Lieberman & Pavane
Hoang Johnny H.
Mannesmann Sachs AG
Wolfe Willis R.
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