EP1605140B1 - Camshaft phaser - Google Patents

Description

The invention relates to an adjusting device for the rotational angle position of the camshaft of a reciprocating internal combustion engine relative to the crankshaft, with an actuator for adjusting the rotational angle position, which is connected in a control circuit having at least one controller.

Such adjusting device with an actuator, which has two intermeshing with helical gears engaged, is off DE 44 08 425 A1 known. One of the gears is connected to the camshaft and the other is driven by a chain from the crankshaft. The gears can be moved against each other by a hydraulic mechanism in a-axial direction, resulting in a relative rotation between the crankshaft and camshaft due to the helical teeth. The hydraulic mechanism is controlled by a control signal, which is generated by means of a control loop. The hydraulic mechanism is each controllable with one of three values, namely an early value for adjusting the camshaft in the direction of early opening of the intake valves of the internal combustion engine, a late value for adjusting the camshaft in the direction of a late opening of the intake valves and a holding value for holding the current actual angular position. The control circuit executes a control program in which the adjustment speed, as will be the case at the beginning of the following program run, is estimated during each program run. From this estimate and the known temporal behavior, which has the camshaft adjustment after switching from the holding value to the control signal (early or late value), the displacement angle is estimated, to which the angular position of the camshaft would still change when the control signal at the beginning of the would be changed to the holding value next program run. If the deviation between the estimated value for the adjustment angle and the target angular position of the camshaft lies within a tolerance band, the early or late value switches over to the holding value. The adjustment speed, which is likely to be present at the beginning of the next program run, is estimated from the current adjustment speed using a first-order transfer function and a final adjustment speed. The final adjustment speed is adapted under certain conditions. According to the disclosure, estimated values for the current position can be determined very accurately even if operating parameters of the hydraulic mechanism change, for example the viscosity of the hydraulic fluid due to heating thereof. Nevertheless, the control quality of the control loop is especially at different operating conditions still in need of improvement. For example, in certain operating situations an overshoot of the signal to be regulated may occur.

More adjusting devices are off WO 2004/007919 A and EP1375837 A known.

There is therefore the task of creating an adjusting device of the type mentioned, which in each case enables a high quality control in different operating situations.

The solution to this problem is that the controller is connected to a data memory are stored in the controller coefficients for a transfer function of the controller that the data memory has at least two memory areas in which different sets of regulator coefficients are stored that the control loop using a Mode switch means is selectively or alternately connectable to one of the data storage areas such that the respective stored in the data storage area Reglerkoeffizientensystemsatz is used in the scheme, and that with the operating mode switching means for detecting the operating state of the adjusting and / or reciprocating internal combustion engine is connected, that in the regulation respectively used Reglerkoeffektenensatz depends on the operating condition.

In an advantageous manner, this makes it possible to operate the controller with different controller coefficients for different operating situations of the adjusting device and / or the internal combustion engine in order to adapt the transfer function of the controller to the respective operating situation and thus to achieve the highest possible quality of control. With such a nonlinear controller, in comparison with a controller with fixed regulator coefficients, disturbances in a signal to be controlled, which is to be influenced by the actuator, can be compensated for more quickly while largely avoiding overshoot. The quantities (n) on the basis of which the regulator coefficients are changed may be measured variables or generated therefrom by suitable algorithms involving system parameters, such as e.g. an electrical resistance, a temperature coefficient, etc. are derived.

It is advantageous if the structure of the control loop can be switched with the aid of the operating mode switching device. The controller can then be better adapted to different operating situations of the adjusting device and / or the internal combustion engine.

Conveniently, the control circuit for controlling the rotor speed of the adjusting motor and in a second mode for controlling the angle of rotation between the camshaft and crankshaft is formed in a first mode. In this case, the first operating mode is preferably used during the starting phase of the internal combustion engine when a measurement signal for crankshaft rotational speed is not yet present or is still subject to relatively large disturbances. As soon as the rotational speed of the internal combustion engine exceeds a predetermined limit value and thus the starting phase has ended, the system switches over to the second operating mode in order to regulate the rotational angle.

In an advantageous embodiment of the invention, the control loop with the help of the operating mode switching means between a third and a fourth mode is switchable, wherein the control circuit is formed in the third mode as a multipoint controller and in the fourth mode for outputting a continuous control signal.

In a preferred embodiment of the invention, the adjusting device to an adjusting gear, which is designed as a three-shaft gear with a crankshaft fixed drive shaft, a camshaft fixed output shaft and an adjusting shaft, wherein an adjusting motor is provided as an actuator, which is in driving connection with the adjusting shaft. The adjusting motor can be an EC motor. To control the phase angle velocity θ to a desired value θ _Tgt , the rotational speed ω _{Cnk of} the crankshaft and the rotor rotational speed ω _{Em of} the adjusting _motor are preferably measured with the aid of sensors. From the measurement signals determined in this way and a known stationary gear ratio ig of the variable speed drive, a desired value ω _Em , _Tgt = (ω _Cnk -i _g θ _Tgt ) / 2 for the rotor speed ω _{Em, Tgt of} the variable displacement _{motor is} calculated with the aid of a signal processing device. The rotational speed ω _{Cnk of} the crankshaft is expediently measured with the aid of an inductive sensor which detects the passage of the teeth of a toothed ring arranged on the crankshaft, for example on a flywheel. The rotor speed ω _{Em of} the variable displacement motor is preferably measured by means of magnetic field sensors arranged on the stator of the EC motor, which detects the passage of magnetic segments which are arranged on the circumference of the permanent magnet rotor of the EC motor.

It is advantageous if the device for determining the operating state has at least one input for a temperature measurement signal of the internal combustion engine and / or the variable displacement motor, and if the device for determining the operating state is designed such that the regulator coefficient set used in the control of this measurement signal (these measurement signals) is dependent. This makes it possible in particular adapt the control loop to the temperature-dependent viscosity of a gear oil of the variable speed gear and / or to the temperature-dependent electrical resistance of the winding of the adjusting motor. The temperature of the internal combustion engine can be measured, for example, with a motor oil thermometer and / or a cooling water thermometer.

In an expedient embodiment of the invention, the device for determining the operating state at least one input for a measurement signal and / or a setpoint signal for the angle of rotation between the camshaft and crankshaft, wherein the means for determining the operating state is designed such that in the control respectively Regulator coefficient set coming to the application of this signal (these signals) and / or the temporal change of this signal (these signals) is dependent. In an adjusting device in which the adjustable phase angle range is limited by stops, then the controller coefficients can be adjusted in the area of the stops such that the control responds relatively slowly to a control deviation, so that overshooting and thus the risk of damage to a stop is reliably avoided , On the other hand, where there is sufficient distance to the stops, the regulator coefficients can be adjusted to compensate for deviations as quickly as possible.

The device for determining the operating state may also have at least one input for a rotor speed of the adjusting motor, the camshaft speed and / or the crankshaft speed representative signal, wherein the means for determining the operating state is designed such that the respectively used in the regulation in the controller set of coefficients depends on this signal (these signals). Each of two of these measurement signals, such as the rotor speed and the crankshaft speed, as well as the known stationary gear ratio of the variable transmission, the angle of rotation (phase angle) between the camshaft and crankshaft can be determined and it can be set the controller coefficients in dependence on the angle of rotation.

It is advantageous if the device for determining the operating state has a memory for temporarily storing at least one previously determined by the controller value of a manipulated variable for the variable motor, and if the means for determining the operating state is designed such that in the control respectively Regulator coefficient set used depends on this value (these values) is. This makes it possible in particular to provide a hysteresis at low adjustment speeds in order to reduce the noise at the output of the controller.

In a preferred embodiment of the invention, the control circuit has at least one limiting device, in particular for the winding current and / or the winding voltage of the adjusting motor, wherein memory locations are provided in the data memory in which limiting values for the limiting device (s) are stored, and in that the limiting device with the help of the operating mode switching device is selectively or alternately connected to one of the memory locations such that the at least one limit value stored in the respective memory location is used in the limitation. The limit values for limiting device (s) can therefore be set as a function of the operating state of the adjusting device and / or the reciprocating internal combustion engine. Thus, for example, in the area of the stops, the limit values for the winding current and / or the winding voltage and thus the power of the adjusting motor can be chosen to be lower in terms of absolute value than at locations which are further away from the stops, so that even if an input error of the input signal occurs Regulator damage to the attacks is safely avoided.

It is particularly advantageous if the control circuit has at least one input connection for a pilot signal connected to at least one pilot control device, and preferably an input connection for a pilot control signal representing the rotational speed of the drive shaft of the variable transmission, an input connection for a pilot control signal representing the average load torque of the variable displacement motor and / or an input terminal for a pilot signal is provided, which represents an induced by the rotation of the permanent magnetic rotor in a winding of the variable displacement electric motor (EMF). The adjustment then allows even faster and more stable control, the control circuit compensates only those deviations between the signal to be controlled and the setpoint, which are not compensated by the feedforward.

Expediently, the data memory has at least two memory areas in which different sets of precontrol coefficients for the pilot control device (s) are stored, wherein the pilot control device (s) with the aid of a mode switching device selectively or alternately connected to one of these data storage areas (are) that the respectively stored pre-tax coefficient set is used in the data storage area in the generation of the at least one pilot signal. Thus, the transfer function (s) of the feedforward control (s) can also be adapted to different Operating conditions of the adjusting and / or the internal combustion engine can be adjusted, which allows an even better control quality.

Fig. 1

eine Verstellvorrichtung zum Verstellen der Drehwinkellage der Nockenwelle einer Hubkolben-Verbrennungsmaschine relativ zu deren Kurbelwelle,

Fig. 2

ein Signalflussdiagramm eines Regelkreises der Verstellvorrichtung.

An exemplary embodiment of the invention is explained in more detail below with reference to the drawing. Show it:

Fig. 1

an adjusting device for adjusting the rotational angle position of the camshaft of a reciprocating internal combustion engine relative to the crankshaft thereof,

Fig. 2

a signal flow diagram of a control loop of the adjustment.

An adjusting device for the rotational angle position of the camshaft relative to the crankshaft of a reciprocating internal combustion engine, not shown in detail in the drawing has an adjusting, which is designed as a three-shaft gear with a crankshaft fixed drive shaft, a camshaft fixed output shaft and an adjusting shaft. The adjusting mechanism may be a planetary gear, preferably a planetary gear.

The drive shaft is rotatably connected to a camshaft gear 1, which is in a conventional manner via a chain or a toothed belt with a rotatably mounted on the crankshaft of the internal combustion engine crankshaft gear in drive connection. The output shaft is rotatably connected to the camshaft 2, which in Fig. 1 only partially shown. The adjusting shaft is rotatably connected to an actuator which in Fig. 1 is arranged at the back of the adjusting device. As an actuator, an adjusting motor (EC motor) is provided, which is integrated in the hub of the camshaft gear 1.

To limit the angle of rotation between the camshaft and the crankshaft, the adjusting device has stops which are formed by a stop element 3 and counter-stop elements 4 connected fixedly to the drive shaft. The counter-stop elements 4 are fixedly connected to the camshaft 2 and act in the use position with the stop element 3 together.

To regulate the angle of rotation of the adjusting motor is in an in Fig. 2 shown schematically connected control circuit 5, which has two cascaded controller, namely a speed controller 6 and an upstream of this phase controller. 7

An input terminal of the phase controller 7 is connected to an output _terminal 8 of a first device 9 for determining a control deviation from a setpoint _signal ε _Tgt and an actual value signal ε for the displacement angle of the camshaft 2 relative to the crankshaft. In Fig. 2 It can be seen that the phase controller 7 has two signal processing devices 10, 11, which are each connected with their input to the output terminal 7 of the device 9 for determining a control deviation. A first signal processing device 10 has a first transfer function with first regulator coefficients K ₁ and a second signal processing device 11 has a second transfer function with second regulator coefficients K ₂ . An output of the first signal processing device 10 is connected to a first input of a first summation device 13 and an output of the second signal processing device 11 is connected via a first integration device 12 to a second input of the first summation device 13.

An output of the first summation device 13 is connected to a first input of a second summation device 14. An input connection 15 for a crankshaft speed _signal ω _Cnk is connected via a first pilot control _device 16 to a second input of the second summation device 14. The first pilot control device 16 has a first pilot control transfer function with first pilot coefficients V ₁ .

An output of the second summation device 14 is connected via a first limiting device 17, which limits the output signal to a predetermined value range, to an output connection for a speed _{setpoint signal .omega.Tgt} for the variable displacement _motor .

The speed _{setpoint signal} ω _Tgt is applied to a first input of a second device 18 for determining a control deviation from the speed _{setpoint signal} ω _Tgt and an actual value signal ω _Em for the speed of the variable displacement motor.

The speed controller 6 has two signal processing devices 19, 20, which are each connected at their input to an output terminal 21 of the second device 18 for determining the control deviation. A third signal processing device 19 has a third transfer function with third regulator coefficients K ₃ and a fourth second signal processing device 11 has a fourth transfer function with fourth regulator coefficients K ₄ . An output of the third signal processing device 19 is connected to a first input of a third summation device 22 and an output of the fourth signal processing device 20 is connected via a second integration device 23 to a second input of the third summation device 22.

An output of the third summation device 22 is connected to a first input of a fourth summation device 24. An input connection 25 for an adjusting motor _load signal M _Load is connected via a second pilot control device 26 to a second input of the fourth summation device 24. The second pilot control device 26 has a second pilot control transfer function with second pilot coefficients V ₂ .

An output of the fourth summation device 24 is connected via a second limiting device 27, which serves to limit the to be output to the adjusting winding voltage U _A to a predetermined range of values, connected to an input terminal of a drive means not shown in the drawing for the adjusting motor.

In Fig. 2 can be seen that the speed controller 6 and the phase controller 7 is connected via an operating mode switching device 28 to a data memory 29 having a plurality of data storage areas, in each of which a set of regulator coefficients is stored, the first regulator coefficients K _1, second regulator coefficients K. ₂ , third regulator coefficients K ₃ and fourth regulator coefficients K ₄ . In the data memory 29 also a plurality of data storage areas are provided, in each of which a set of precontrol coefficients is stored, each comprising the first precontrol coefficients V ₁ and second precontrol coefficients V ₂ .

The speed controller 6 and the phase controller 7 can be selectively or alternately connected to one of the data storage areas by means of the operating mode switching device 28 such that the regulator coefficient set stored in the respective data storage area is stored in the control and / or in the respective data storage area Precontrol coefficient set is used (come) in the pre-control.

As in Fig. 2 It can also be seen that a device 30 for determining the operating state of the adjusting device and the reciprocating internal combustion engine are connected to the operating mode switching device 28 and the data memory 29 in such a way that the set of control coefficients and / or the pilot control respectively used for the control are each used for the input pilot coefficient set depends on the operating state. The operating state determining means 30 has a plurality of inputs connected to crankshaft speed measuring sensors, internal combustion engine oil temperature, adjusting motor speed, an output of the second limiting means 27, and an engine control output port for the internal combustion engine to which a signal for an operating mode (engine start / stop, normal running, emergency) of the internal combustion engine is applied. The device 30 for determining the operating state has a comparison device which compares the signals applied to the inputs with predetermined value ranges. Depending on the results of these comparisons, a respective operating state is determined, which controls the selection of the respectively to be used regulator and pilot coefficient sets.

The operating mode switching device 28 also allows a changeover of the structure of the control loop. In a first operating mode of the control loop, the regulator coefficients K _1, K ₂ and the precontrol coefficients V _{1 have} the value zero, while the regulator coefficients K ₃ , K ₄ and the precontrol coefficients V _{2 are} not equal to zero. The control circuit 5 then controls only the rotor speed of the adjusting motor. This operating mode is preferably used during the starting phase of the internal combustion engine.

In a second operating mode of the control loop, all the regulator coefficients K ₁ , K ₂ , K ₃ , K ₄ and pilot control coefficients V ₁ , V _{2 are} not equal to zero, so that the control circuit 5 then controls the angle of rotation between the camshaft 2 and the crankshaft and the rotor speed. The second operating mode is used when the speed of the internal combustion engine exceeds a predetermined minimum value.

LIST OF REFERENCE NUMBERS

1

camshaft gear

2

camshaft

3

stop element

4

Counter-stop element

5

loop

6

Speed controller

7

Phase regulator

8th

output port

9

first device for determining a control deviation

10

first signal processing device

11

second signal processing device

12

first integration device

13

first summation device

14

second summation device

15

Input connection for a crankshaft speed signal (ω _Cnk

16

first pilot control device

17

first limiting device

18

second device for determining a control deviation

19

third signal processing device

20

fourth signal processing device

21

output port

22

third summation device

23

second integration device

24

fourth summation device

25

Input connection for an adjustment motor _load signal M _Load

26

second pilot control device

27

second limiting device

28

mode switching

29

data storage

30

Device for determining the operating condition

Claims (10)

1. Adjustment device for adjusting the rotational angle position of the camshaft (2) of a reciprocating-piston internal combustion engine relative to the crankshaft, having an adjustment motor as a positioning element for the adjustment of the rotational angle position, which adjustment motor is connected into a control loop (5) which has at least one controller (6, 7), wherein the controller (6, 7) is connected to a data memory (29) in which controller coefficients for a transfer function of the controller (6, 7) are stored, in that the data memory (29) has at least two memory regions in which different sets of controller coefficients are stored, in that the control loop (5) is, with the aid of an operating mode switching device (28), connectable selectively or alternately to one of the data memory regions such that the controller coefficients set stored in each case in the respective data memory region is used in the control, and in that a device (30) for detecting the operating state of the adjustment device and/or of the reciprocating-piston internal combustion engine is connected to the operating mode switching device (28) such that the controller coefficient set respectively used in the control is dependent on the operating state, characterized in that, by way of the operating mode switching device (28), by means of the respectively used controller coefficient set, in a first operating mode which is used during the starting phase of the internal combustion engine, the control loop (5) is configured only for controlling the rotor rotational speed of the adjustment motor for the rotational angle position, and in a second operating mode, after a predefined minimum rotational speed of the crankshaft has been overshot, the control loop (5) is configured for controlling the relative rotational angle between camshaft (2) and crankshaft.
2. Adjustment device according to Claim 1, characterized in that, with the aid of the operating mode switching device (28), the control loop (5) can be switched between a third and a fourth operating mode, and in that, in the third operating mode, the control loop (5) is configured as a multipoint regulator, and in the fourth operating mode, the control loop is configured for outputting a continuous positioning signal.
3. Adjustment device according to Claim 1 or 2, characterized in that said adjustment device has an adjustment gearing which is in the form of a three-shaft gearing with a drive-input shaft fixed to the crankshaft, a drive-output shaft fixed to the camshaft, and an adjustment shaft, and in that, as a positioning element, an adjustment motor is provided which has a drive connection to the adjustment shaft.
4. Adjustment device according to one of Claims 1 to 3, characterized in that the device (30) for detecting the operating state has at least one input for a temperature measurement signal of the internal combustion engine and/or of the adjustment motor, and in that the device (30) for detecting the operating state is configured such that the controller coefficient set respectively used in the control is dependent on said measurement signal (measurement signals).
5. Adjustment device according to one of Claims 1 to 4, characterized in that the device (30) for detecting the operating state has at least one input for a measurement signal and/or a setpoint value signal for the relative angle of rotation between camshaft and crankshaft, and in that the device for detecting the operating state (30) is configured such that the controller coefficient set respectively used in the control is dependent on said signal (said signals) and/or on the change with respect to time of said signal (of said signal).
6. Adjustment device according to one of Claims 1 to 5, characterized in that the device (30) for detecting the operating state has at least one input for a signal which represents the rotor rotational speed of the adjustment motor, the camshaft rotational speed and/or the crankshaft rotational speed, and in that the device (30) for detecting the operating state is configured such that the controller coefficient set respectively used in the control is dependent on said signal (said signal).
7. Adjustment device according to one of Claims 1 to 6, characterized in that the device (30) for detecting the operating state has a memory for the temporary storage of at least one value, determined by the controller (6, 7) at an earlier point in time, of a positioning variable for the adjustment motor, and in that the device (30) for detecting the operating state is configured such that the controller coefficient set respectively used in the control is dependent on said value (said values).
8. Adjustment device according to one of Claims 1 to 7, characterized in that the control loop (5) has at least one limitation device (17, 27), in particular for the coil current and/or the coil voltage of the adjustment motor, in that, in the data memory (29), there are provided memory locations in which limit values for the limitation device(s) (17, 27) are stored, and in that the limitation device (17, 27) is selectively or alternately connectable, with the aid of the operating mode switching device (28), to one of the memory locations such that the at least one limit value stored in each case in the respective memory location is used in the limitation.
9. Adjustment device according to one of Claims 1 to 8, characterized in that the control loop (5) has at least one input terminal (15, 25), which is connected to at least one pilot-control device (16, 26), for a pilot-control signal, and in that, preferably, an input terminal (15) is provided for a pilot-control signal which represents the rotational speed of the drive-input shaft of the adjustment gearing, an input terminal (25) is provided for a pilot-control signal which represents the mean load torque of the adjustment motor, and/or an input terminal is provided for a pilot-control signal which represents an electrical voltage (EMF) that is induced in a coil of the adjustment motor by the rotation of the permanently magnetic rotor.
10. Adjustment device according to one of Claims 1 to 9, characterised in that the data memory has at least two memory regions in which different sets of pilot-control coefficients for the pilot-control device(s) are stored, and in that the pilot-control device(s) is (are) selectively or alternately connectable, with the aid of the operating mode switching device (28), to one of said data memory regions such that the pilot-control coefficient set stored in each case in the respective data memory region is used in the generation of the at least one pilot-control signal.

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