DE19936885A1 - Internal combustion engine switch-off method involves controlling or regulating braking torque of electric machine so crankshaft stops in stable rest position after fuel supply cut-off - Google Patents

Abstract

The method involves braking the engine crankshaft with the braking torque of an electric machine after interrupting a fuel supply process. The braking torque is controlled or regulated so that the crankshaft stops in a stable rest position.

Description

The invention relates to a method for parking an internal combustion engine according to that in the preamble of Claim 1 defined art.

In hybrid vehicles with an internal combustion engine and the internal combustion engine can select an electric machine While driving, shutdown by a control unit and starts again from this control unit become. The driver of the corresponding vehicle has however, no direct input to these processes themselves flow. If possible, he should not or be minimally troubled.

In addition to the acoustic effect, the sounds of the Internal combustion engine, most drivers feel here the vibration effect rather than disturbing. This "shaking" the internal combustion engine and ge if necessary, a gearbox connected to it generates vibrations in the entire vehicle, which  true by the driver and the other vehicle occupants be taken.

Especially in hybrid vehicles, where this Parking the internal combustion engine while driving this is perceived as particularly unpleasant.

The same applies to automatic so-called "Start / Stop" systems in which the internal combustion engine ne of a vehicle z. B. during a stop at an engine control unit is turned off and when the vehicle is started again.

This parking process also leads to an unstable pleasant, undesirable vibration effect by shaking the engine and if necessary, the transmission.

The acoustic effects of the shutdown process are over a corresponding sound insulation comparatively easy to reduce in terms of vibration technology However, the effects are sufficient insulation or decoupling problematic.

It is therefore an object of the invention, the vibrations an internal combustion engine during its shutdown reduce or avoid almost completely and so that Shake the engine or a cure To prevent belwelle the internal combustion engine.

According to the invention, this task is characterized by the drawing part of claim 1 mentioned features solved.  

It is provided in the case of the invention of a hybrid drive to use the electric machine, which is also used for the electromechanical propulsion of the Vehicle. Alternatively, for the inventor appropriate braking of the crankshaft z. B. at one Start / stop system, however, also the electric machine are used, which are usually used to start the Internal combustion engine or as a generator is provided.

In addition to its simple equipment structure, this offers Method according to the invention for switching off a burner engine the advantage that with great accuracy speed the crankshaft is at rest can. A standard internal combustion engine is one settable, which none through the procedure to their Abandoning modifications in mechanical or the control or regulatory area of Internal combustion engine requires.

The braking process of the internal combustion engine is over one According to the invention generated by the electric machine Brake torque designed so that the standstill Crankshaft in a position in which the cure belwelle persists without shaking, that is, in a stable rest position. This stable calm position is reached when there are no external influences the crankshaft act and / or if together with be agreed external influences such. B. with Schleppmo elements of a summing gear, no shaking the crankshaft and parts connected to it.

This therefore has the advantage that in comparison to a conventional shutdown of a burner the crankshaft before it stops  between the compression strokes of the individual cylinders shakes back and forth until it comes to rest.

In a particularly favorable embodiment of the Er the system can have a sensor system, which che position and movement of the crankshaft detected and transmitted to a control or regulating device, the control device regulating the data of the Sensor technology according to the angular position and angular velocity of the Evaluates the crankshaft and that via the electric machine generated braking torque on the crankshaft controls or regulates.

The invention can now advantageously this Use signals to derive two quantities, the to realize one of the advantageous further training extensions of the invention are essential. On the one hand is this is the measure of the current angular velocity, which z. B. from the interval between two successive pulses of a sensor wheel on the Crankshaft can be determined. On the other hand, it is Relation of the position of the crankshaft to the stable one Rest position of the crankshaft, which makes it possible to determine the current angular position of the crankshaft men.

With the equations of motion, time can points and the braking torques to be realized for a fast, shake-free reaching of the rest position the crankshaft can be determined. The one for braking The electric machine used in the crankshaft can then be controlled so that they do so required braking torque is generated. You can also during the course of the inventive method  rens further control or regulatory engineering leg flows of the electric machine.

Depending on whether the invention in a hybrid vehicle or around a start / stop system on the one hand the electric machine for the drive, the other on the other hand, that for starting the internal combustion engine machine for generating the controlled according to the invention or controlled braking torque.

Further particularly advantageous embodiments of the Invention result from the dependent claims and the Darge in principle based on the drawings presented embodiment.

It shows:

Figure 1 is a schematic diagram of a Abstellvor gear for a six-cylinder 4-stroke internal combustion engine with a rest position of 60 ° after top dead center of the compression. and

FIG. 2 shows a basic diagram of a profile of an angular velocity of the crankshaft during the shutdown process according to FIG. 1.

In Fig. 1, a diagram is shown in which on the ordinate the angle ϕ _kW in degrees (°) is carried by a crankshaft of an internal combustion engine. The abscissa represents the time axis t, which has a scaling in milliseconds (ms) before the crankshaft is at rest - at 0 ms.

The version shown in its operating principle Example of the procedure for turning off the burner engine refers to a six cylinder 4- Stroke internal combustion engine. With such a fuel machine repeats a compression TDC (upper Dead center) each of a piston of the internal combustion engine every 120 ° of crankshaft rotation. So that means, that every 120 ° of rotation of the crankshaft each one of the six pistons during a maximum phase Compression (compression cycle) between each gases enclosed in the cylinder and the piston its OT location. The neutral standstill or the stable rest position of the crankshaft is included an internal combustion engine approximately in the middle between the compression top layers, d. H. in the present case offset by approx. 60 ° to the compression TDCs.

An existing on the internal combustion engine Motorelek electronics or an engine control unit generates for its own purposes, for. B. to control the ignition or injection, trigger signals from pulses generated by a transmitter wheel, which can be designed as a gear, on the flywheel of the crankshaft. From these z. B. triggered by the teeth of the sensor wheel pulses, the engine electronics he obe ren dead center OT of the piston of the first cylinder. As a result, given the known number of cylinders and strokes of the internal combustion engine, the engine electronics can also determine the respective angle ϕ _KW , which is to be assigned to the respective top dead center OT remaining cylinders.

The trigger signals now point from the engine electronics generated trigger marks based on the  Compression TDCs from one of the cylinders pull. The trigger marks can e.g. B. as rising and falling signal edges in the trigger signal be recognizable. The engine electronics usually generate tronik trigger signals with the rising signal flange ken 6 ° before the respective cylinder TDC and the sinking Signal edges 48 ° afterwards.

Now the trigger signals of the engine electronics beyond their originally intended purpose also for the method for switching off an internal combustion engine machine used. From the trigger brands, that is rising or falling signal edges, can be derive two quantities which are necessary for the realization of the ver driving essential to turn off the engine are.

On the one hand, a measure of an instantaneous angular velocity ω _KW , which is derived from the time intervals between z. B. results in two rising signal edges or two trigger marks and on the other hand a relation of the trigger marks, which correspond to the cylinder TDC's or are proportional to the rest of the course belwelle. So that the position or the angular position ϕ _{KW of} the crankshaft at the respective time be known.

In the event that there is no motor electronics, such signals can of course also be on way, especially for the procedure for Parking an internal combustion engine, are generated. A special control unit for the parking process could e.g. B. the pulses from the encoder wheel on the Evaluate the crankshaft flywheel.  

The diagram shown in Fig. 1 shows an example of a shutdown for the above-mentioned six-cylinder 4-stroke engine with a rest position of 60 ° after the compression TDCs. A curve X of the win kellage of the crankshaft initially begins as a straight line. This means that there is a constant angular velocity ω _KW (see also Fig. 2) before, here rotational irregularities of the crankshaft have been neglected for the sake of clarity.

The one with the slope of the straight section of the curve X related speed may e.g. B. the Idle speed of the internal combustion engine to be that before the shutdown of the engine control unit or Engine electronics was started, this too Shutting down the engine to idle speed can already be part of the shutdown process.

The fuel is then at a point S of the curve X. fine injection switched off and the active braking of the Internal combustion engine is powered by an electric machine headed.

It is for the procedure for turning off the Internal combustion engine in principle unimportant whether the point S in a functional angular relationship to the cure belwelle stands or whether he arbitrarily, z. B. directly from a signal from the ignition key or the engine electronics nik, is triggered, and whether the speed of idling speed corresponds to or is another.  

Points A to 6 continuously designated in the alphabet mark z. B. trigger brands, which here at the Six-cylinder 4-stroke internal combustion engine in 120 ° Successive steps of crankshaft rotation corresponding compression TDC points. At 60 ° after point G, roughly between two Compression OT's, be that in the example shown Rest position of the crankshaft reached at a point T. The braking process of the crankshaft can, for. B. as Darge who realizes by a constant torque the. In this case, the curve X describes the Points or trigger marks A to G a parabolic moderate course. Again, the turns are the same formations of the crankshaft neglected, which at large braking torques in relation to that of the Compression resulting in low torques is casual.

Fig. 2 describes in a diagram the course of the angular velocity ω _{kW of} the crankshaft. Since angular velocity ω _kW and angle ϕ _{kW are} in a different connection, the angular velocity ω _{kW is} constant up to point S and then falls in two straight lines with different gradients first to point G and then to the rest position T of the crankshaft ( Angular velocity ω _kW = 0).

The time periods that elapse between the trigger points A, B, C, D, etc. give a measure of how far the angular velocity ω _kW has approached the standstill of the crankshaft. By comparing these time periods with e.g. B. stored in a map th sizes or target time spans, who can determine when a limit time Z is reached, after which the Ruhela ge of the crankshaft is to be reached in one of the following 120 ° intervals. This means that the crankshaft as soon as the angular velocity ω _KW is low enough, from this small Winkelge speed ω _KW , precisely with respect to that of the angle ϕ _KW , is completely braked to its stable rest position (Winkelge speed ω _KW = 0).

The end point G of the limit time period Z is therefore the Trigger mark selected at which the rest of the brake course is started. It can be from the size of time span Z and from the current values in point F. Application of the equations of motion to the Winkelge speed can be closed at point G. Moreover this creates a connection for a new one Braking torque and a braking time R until it is reached of point T, i.e. the standstill of the crankshaft. This relationship can also be in a map be filed or with simple, from the movement algorithms to be derived be counted.

The limit time periods and the target time periods can Thereby as stored in one or more maps Values are specified. The values in the Maps depending on the braking torque and / or the speed at the time of the interruption the fuel supply. This enables egg a quick schedule because the tax or Control device after the interruption of the Fuel supply begins its work, then be start at a fairly well-adjusted starting value  can.

The electric machine will be the newly calculated Braking torque and the braking time R to a standstill the crankshaft in its stable rest position as a new one Preset values. The control device then ensures that these new values from the elec tromaschine can be realized on the crankshaft.

Because of the already low angular speeds the crankshaft shortly before reaching point G it is not important whether the control signals z. B. in In case of transmission via a CAN bus (computer area network) a small time delay ent hold, so only one or two time steps an event causing it. As the CAN bus system increasingly. Spread in force vehicles finds, it is therefore appropriate to this also for the transmission of data for the procedure to use to shut off an internal combustion engine.

In a further embodiment of the method for Parking the internal combustion engine, which is in the dia is not considered, it can Braking torque of the electric machine before reaching it controlled the stable rest position of the crankshaft be that the support reaction of the motor housing done without much shaking. This can e.g. B. there be achieved by that after an initial star The braking torque is downgraded is, so that in the backshaking phase of the housing Internal combustion engine still has a counter torque remains, which also avoids this shaking.

Claims (8)

1. A method for turning off an internal combustion engine, wherein a crankshaft of the internal combustion engine is mechanically connected to at least one electrical machine, characterized in that the crankshaft of the internal combustion engine is braked by a braking torque after an interruption of a fuel supply from the electrical machine, the braking torque in the Art controlled or regulated that the standstill of the crankshaft takes place in a stable rest position of the crankshaft. 2. A method for stopping an internal combustion engine according to claim 1, characterized in that a sensor system detects the position and movement of the crankshaft le and transmits it to a control or regulating device, the control or regulating device transmitting the data of the sensor system according to the angular position (ϕ _kW ) and the angular velocity (ω _kW ) of the crankshaft are evaluated and the braking torque generated by the electric machine on the crankshaft is controlled or regulated. 3. Method for switching off an internal combustion engine according to claim 1 or 2, characterized in that Trigger signals are generated from the sensor data be, the trigger signals trigger marks (A to G) contain, which the each other the following top dead centers of one cy linders of the internal combustion engine are proportional. 4. A method for stopping an internal combustion engine according to claim 3, characterized in that elapsing time periods are detected between the individual trigger marks (A to G), the time periods being compared with predetermined target time periods, when reaching a given limit time period (Z) the angular velocity (ω _kW ) of the crankshaft is calculated in advance when the following trigger mark (G) is reached, and, together with an angular distance between the crankshaft between the top dead center of a piston in a cylinder and the rest position of the cure, a braking time (R) and a value for the braking torque to be realized after reaching the subsequent trigger mark (G) is determined. 5. Method for switching off an internal combustion engine according to claim 4, characterized in that the target time periods and / or the limit time period (Z) as a function of the braking torque and / or the speed at the time (S) of the interruption  the fuel supply to the internal combustion engine in be stored in at least one map. 6. Method of stopping an internal combustion engine according to one of claims 1 to 5, characterized in that the transmission of the tax or regulation and / or Measurement data via a CAN bus system (computer area network). 7. Method for switching off an internal combustion engine according to one of claims 1 to 6, characterized in that the braking torque shortly before reaching Ruhela ge (T) of the crankshaft controlled in style or it is regulated that drag torques of a transmission or summing gear between the crankshaft and of the electric machine that of the electric machine generated braking torque counteracts. 8. Method for switching off an internal combustion engine according to claims 1 to 7, characterized in that the braking torque shortly before reaching Ruhela ge (T) of the crankshaft is reduced in the way that in a backshaking phase of the housing Internal combustion engine has a counter torque remains that generated by the electrical machine Counteracts braking torque.