DE102005047578A1 - Method for determining the torque of an internal combustion engine - Google Patents

Abstract

Method for determining the torque (M_A) of an internal combustion engine (1), characterized in that movements (X, Y) of the internal combustion engine (1) are recorded and a torque (M_A) output by the internal combustion engine is determined therefrom.

Description

The The present invention relates to a method for determining torque an internal combustion engine and a device, in particular a motor vehicle, with an internal combustion engine that transmits torque to a drive train emits.

The delivered actual torque of an internal combustion engine, below short referred to as torque of the internal combustion engine, is for the controller different operating parameters of the internal combustion engine of Importance. In particular, based on a current, i. to a certain time, torque output a comparison between the target torque and the actual torque take place, which for example, in a working cycle of a single cylinder immediately Conclusions on actually injected fuel quantity of a diesel engine or a directly injecting Gasoline engine allows. The actual torque is nowadays usually in the drive train not recorded. The target torque of the internal combustion engine is both in a diesel engine as well as in a direct injection Gasoline engine, among other things on the injected fuel quantity controlled.

It is used in today's controls for Internal combustion engines operated a considerable effort to the quantity dispersion of the system, in particular an injector to compensate. To a variety of methods are used, for example a Zero-flow calibration, idle-cruise control, injector flow compensation, Mean value adaptation and the like. Such adjustments are necessary because the injected amount not ge measured and thus regulated, but only indirectly, for example via the torque output, Combustion chamber pressures or the like can be detected.

task The present invention is therefore an easy to implement Specify torque detection on the internal combustion engine. In addition, should the resolution of the Torque detection sufficient to cylinder-selective torques capture.

Advantages of invention

The above problem is solved by a method for torque determination of an internal combustion engine, wherein movements of the internal combustion engine are detected and from it determined by the internal combustion engine torque becomes. Under movements, relative movements become a fixed, especially body-fixed reference system understood, for example So vibrations of an internal combustion engine with respect to their suspension. Especially Here are under movements oscillations of an engine block Internal combustion engine opposite their body-mounted suspension understood in a motor vehicle. Internal combustion engines are in vehicles spring-mounted. Since the internal combustion engine in the frequency of Operating cycles impulsively outputs torque, resulting in a shaking motion of the engine due to inertia of the drive train. This shaking is expressed z. B. in rotational movements of the motor housing to the crankshaft.

Preferably is provided that the movements of the internal combustion engine during a power stroke at least one cylinder are detected and that by the cylinder generated torque is determined. So it will be an assignment of the each delivered torque is operated on a single cylinder. Here is the crankshaft angle and the power stroke of each Cylinder respectively known, so that an assignment of the torque output over the Crankshaft angle is given.

Preferably It is envisaged that rotational movements of the internal combustion engine relative to a body-mounted suspension be measured and taken into account the rotational inertia the internal combustion engine, the torque generated by a cylinder is determined. The body of a motor vehicle is here so as a fixed reference system for the relative movements of the internal combustion engine within the body used. Preferably, it is provided that frequency, phase position and amplitude of the movements / vibrations of the internal combustion engine be measured. The movements express themselves in vibrations with a frequency spectrum. The fundamental frequency can thereby by a bandpass for the determination of phase position and amplitude the movements / vibrations of the internal combustion engine filtered out become. Since the fundamental frequency from the speed of the internal combustion engine is known (F = N / 60 * Z / 2) the pass frequency of the bandpass filter can be calculated from the speed of the internal combustion engine be determined and carried along in case of changes. In a particularly simple embodiment, the fundamental frequency through a low pass for the determination of phase angle and amplitude filtered out in the movement / vibration of the internal combustion engine become. Instead of a bandpass you can do a simpler low pass be used.

The problem mentioned above is also solved by a device, in particular a Motor vehicle, with an internal combustion engine, which outputs a torque to a drive train, wherein the device comprises means for measuring a movement of the internal combustion engine and the output torque can be determined from the measurement of the movement of the internal combustion engine.

drawings

following is an embodiment of Present invention explained in more detail with reference to the accompanying drawings. there demonstrate:

1 a sketch of an internal combustion engine;

2 a frequency spectrum of shaking motions of an internal combustion engine;

3 an arrangement for speed detection in an internal combustion engine;

4 a flow diagram of the method according to the invention.

1 shows a sketch of an internal combustion engine 1 with an engine block 2 , several cylinders 3 in which, in a known manner, pistons connecting via connecting rods on a camshaft 4 act, are arranged and a cylinder head 5 , The internal combustion engine 1 is arranged in an engine compartment of a vehicle, not shown, wherein the internal combustion engine 1 on the one hand on the crankshaft 4 and a vehicle clutch, not shown, and also not shown gear, on the other hand, several engine block suspensions 6 is supported on a vehicle body, not shown.

When the internal combustion engine 1 a drive torque M_A over the crankshaft 4 to the other powertrain of the vehicle, not shown, requires the torque balance that a corresponding support torque M_S is introduced via the engine mount in the body of the vehicle. If the drive torque M_A is not constant, but variable over time, then the moment of inertia M_T of the internal combustion engine is additionally for the moment equilibrium 1 to take into account, where all moments add up to 0.

The engine block suspensions 6 include engine block resistant elements 7 as well as body-fixed elements 9 that have elastic connection means 8th connected to each other.

Due to the elastic suspension of the internal combustion engine performs this rotational movement or linear movement x and y. With x are here movements of the engine block fixed elements 7 opposite the body-worn elements 9 denotes, with y are exemplary movements of the cylinder head 5 referred to the body.

The Internal combustion engine gives the torque M_A in the frequency of the power strokes impulsively. This results in a shaking movement of the internal combustion engine in the form of movements x and y due to the inertia of the drive train. These shaking movements hang in terms of their frequency from the engine speed, with respect to the amplitude hang these from the power output and with respect to the phase angle from the ignition.

The self-adjusting central position or zero position of the internal combustion engine or of the engine block in the rotatably mounted suspension a direct measure of the mean delivered power. The engine block oscillates around its zero position, so If the internal combustion engine is idling, its middle position negative, so the engine is in overrun, is the middle position positive, so the engine gives a torque from. A positive deflection is contrary to a rotation from the zero position the direction of rotation of the crankshaft, a negative deflection accordingly in the direction of rotation of the crankshaft.

The movements x and y, for example, by a suitable transducer 10 This may be, for example, a laser measuring system or the like, or via piezo pickups, strain gauges or the like between the engine block-fixed elements 7 and the body-worn elements 9 respectively.

2 shows an example of a measured frequency spectrum for a V8 engine shown at different speeds. Shown are movements, such as in 1 shown, the paths X and Y, for example in millimeters above the speed N of the internal combustion engine. The main excitation can be recognized in the front area of the diagram, ie at low frequency, and marked with a line F_H. The frequency F_H of the main excitation is calculated to F_H = N / 60 · Z / 2 in which
F_H = the frequency of the main stimulus in Hertz,
Z = the number of cylinders,
N = the speed of the motor in revolutions per minute.

As the engine speed and the number of cylinders are known in the control unit, a bandpass can be tracked by software, which filters out the frequency F_H and thus phase position and amplitude fluctuations are evaluated. In the first approximation, a pure lowpass is sufficient, since the frequency components below the excitation frequency F_H are very low and frequency, phase position and amplitude fluctuations are required, above all in the lower rpm range. This correlates directly with the smoothness and, with the appropriate resolution accuracy, allows a conclusion to be drawn about the injection time and the injection quantity. The recording of the vibrations must take place via a suitable measuring system, for example a laser, a modified yaw rate sensor or a piezoelectric pickup at the support points of the internal combustion engine.

At a speed of, for example 1500 U / min according to 2 For example, a bandpass with a pass frequency in the range of 100 hertz, for example 90 to 110 hertz, could be applied to the measurement signal of the shaking motion in the form of, for example, paths x and y. From the amplitude of this shaking motion, the spring stiffness and damping of the engine mount and the mass moment of inertia of the internal combustion engine - so this is not negligible compared to the bearing forces - the torque M_A can be determined directly. The torque curve M_A over time, which is determined therefrom, permits a conclusion about the injection time and, by means of a corresponding modeling of the combustion process, a conclusion about the injection quantity.

In an alternative embodiment, the detection of the rotational movement of the engine block takes place via a modified speed sensor of the internal combustion engine. With the crankshaft of the internal combustion engine is a donor disc according to 3 connected.

3 shows a sketch with a donor disk 11 , for example, directly on the crankshaft 4 is arranged or indirectly by means of gear elements with respect to the rotation with the crankshaft 4 or one in 1 not shown camshaft is connected. The encoder disc 11 rotates about an axis 12 , On the outer circumference of the encoder disk 11 are donor wheel brands 13 arranged. The donor wheel brands 13 for example, consist of teeth 14 , each equidistant over the outer circumference of the encoder disk 11 are arranged. Between the teeth 14 are each tooth spaces 17 arranged. Another donor wheel gap 15 For example, as shown here in the form of a twice as wide tooth gap 17 a wider or twice as wide tooth 14 or the like, marks a designated zero position of the crankshaft. At the encoder wheel disk 11 is a first donor 16 arranged, which provides an electrical signal that in the form of, for example, a rectangular signal teeth 14 and tooth gaps 17 or the gear wheel gap 15 represents. By rotation of the crankshaft 4 or the camshaft and thus the encoder disc 11 each become the teeth 14 as well as the gear wheel gap 15 at the first donor 16 past. As a result, for example, an electrical signal in the first encoder 16 triggered. The first donor 16 may be an inductive sensor, a Hall sensor, a capacitive sensor or the like. Alternatively, this can also work optically, for example when this through the teeth 14 or the mark 15 can measure evoked optical changes.

The first donor 16 is stuck to the internal combustion engine 1 arranged and thus motor housing fixed. In addition, now a second encoder 18 body shop arranged. The second donor 18 makes in contrast to the first donor 16 Shaking the internal combustion engine not with. By comparing the signals of the first encoder 16 with the signal of the second encoder 18 Therefore, relative movements of the internal combustion engine relative to the body can be detected.

4 shows a flowchart of the method according to the invention. First, in step 101 Movements, for example, as previously shown using the paths X, Y of the engine relative to the body detected with corresponding transducers. The associated frequency spectrum will now be in step 102 fed to a bandpass filter BP. The bandpass filter filters out the frequency of the main stimulus, which is in step 103 on amplitude fluctuations AS and in step 104 is evaluated on the phase position PL. In step 105 is finally determined from the previously obtained data on frequency, amplitude fluctuations and phase position a torque output M_A the internal combustion engine.

Claims (8)

Method for determining the torque (M_A) of an internal combustion engine ( 1 ), characterized in that movements (X, Y) of the internal combustion engine ( 1 ) are detected and from this a torque output by the internal combustion engine (M_A) is determined. A method according to claim 1, characterized in that from the movements of the internal combustion engine ( 1 ) a torque currently delivered by individual cylinders of the internal combustion engine (M_A) is determined. A method according to claim 1, characterized in that the movements of Brennkraftma machine ( 1 ) are detected during a power stroke of at least one cylinder and the torque generated by the cylinder (M_A) is determined. Method according to one of the preceding claims, characterized in that rotational movements of the internal combustion engine ( 1 ) are measured relative to a body-mounted suspension and taking into account the rotational inertia of the internal combustion engine ( 1 ) determines the torque generated by a cylinder. Method according to one of the preceding claims, characterized in that frequency, phase position and amplitude of the movement of the internal combustion engine ( 1 ) are measured. Method according to one of the preceding claims, characterized in that a fundamental frequency (F = n / 60 * z / 2) by a bandpass for determining the phase position and amplitude of the movement of the internal combustion engine ( 1 ) is filtered out. Method according to one of the preceding claims, characterized in that a fundamental frequency (F = n / 60 * z / 2) by a low-pass filter for determining the phase position and amplitude of the movement of the internal combustion engine ( 1 ) is filtered out. Device, in particular motor vehicle, with an internal combustion engine ( 1 ), which outputs a torque (M_A) to a drive train, characterized in that the device comprises means for measuring a movement of the internal combustion engine ( 1 ) and the output torque from the measurement of the movement of the internal combustion engine ( 1 ) can be determined.