ANGLE POSITION DETECTION DEVICE IN A HYBRID VEHICLE

Description

[0001] The invention relates to an angular position detection device in a hybrid vehicle equipped with an internal combustion engine and an electric motor.

[0002] The applicant's unpublished German patent application 10 2020 112 471 relates to a device for reducing vibration excitations of a motor-transmission system in a hybrid vehicle, comprising an internal combustion engine, an electric motor, an electric motor control unit, an internal combustion engine control unit, and a communication bus between the electric motor control unit and the internal combustion engine control unit. By appropriately programming the electric motor control unit, a torque is generated by the electric motor that reduces the vibration excitations of the motor-transmission system. In this case, an angular reference (in the form of a constant angular offset) between the electric motor and the internal combustion engine, determined when the internal combustion engine is stationary or slowly rotating, is taken into account; the precise determination of this angular reference is not discussed in detail.

[0003] JP 2001 020797 A discloses a drive device with an internal combustion engine and an electric motor connected via a clutch. The drive device has means for detecting the angular position of the output shafts of both drive motors.

[0004] DE 11 2015 006 459 T5 discloses a control device for a hybrid vehicle in which a crankshaft of an internal combustion engine is connected to a motor generator. The control device comprises a crankshaft angle sensor configured to detect an angle of a crankshaft, a rotor angle sensor configured to detect an angle of a rotor of a motor generator, and a calculation unit configured to determine whether a condition for ensuring that an error in a phase difference between the angle of the crankshaft and the angle of the rotor of the motor generator is reduced is met and to calculate the phase difference if the error in the phase difference is determined to be small.

[0005] KR 2018 0032301 A discloses a method for compensating an engine stop angle in a hybrid vehicle, in which an engine management system of the hybrid vehicle compensates for an engine stop angle without using rotor angle information from an engine control unit.

[0006] The object of the present invention is to improve the detection of the angle reference, in particular for such a device for reducing vibration excitations of an engine transmission system in a hybrid vehicle.

[0007] This object is achieved by the independent claims. Advantageous embodiments are described in particular in the dependent claims.

[0008] The invention relates to an angular position detection device in a hybrid vehicle equipped with an internal combustion engine and an electric machine, with a crankshaft sensor for detecting an absolute internal combustion engine angular position with respect to a defined position mark, with a rotor position sensor for detecting a relative electric machine angular position with respect to a reference point (preferably reference pole, which is one of several similar rotor poles), and with at least one electronic control unit.The at least one control unit, preferably an internal combustion engine control unit and an electric machine control unit, is (or are) designed (in particular programmed) in such a way that the absolute internal combustion engine angular position and the relative electric machine angular position are detected when the internal combustion engine and the electric machine are stationary, and that, based on these angular positions, a mechanical angular reference of the internal combustion engine to the electric machine is determined and stored as an angular difference between the position mark and an initial reference point in the form of an initial reference pole.

[0009] Preferably, at a first stop or before the first start of the combustion engine and the electric machine, a mechanical initial angle reference is determined in relation to the initial reference point in the sense of a learning function.

[0010] At each subsequent start after the first start of the combustion engine and the electric machine, the calculation is preferably continued with the reference point already stored in the electric machine control unit, whereby in the event of an error the geometrically nearest pole is selected as the new reference point.

[0011] In addition, the following adjustment function is carried out after a learning function: With each subsequent start and / or stop of the combustion engine and the electric machine, the current mechanical angle reference is adjusted, whereby a first adjustment component represents the pole jumps between the initial reference point and the new reference point and whereby a second adjustment component represents the mean value between the current mechanical angle reference and the newly calculated mechanical angle reference taking into account the first adjustment component.

[0012] In general, the angle reference of the internal combustion engine to the electric machine according to the invention enables any application on one of the control units with the angle / speed information of the other control unit and their calculations when an internal combustion engine control unit and an electric machine control unit communicate with each other via a bus.

[0013] When reference is made below to a stationary combustion engine or a stationary electric machine, this also includes a state of being at least almost stationary or rotating only slowly.

[0014] The invention is based on the following considerations: For example, in combustion engines (gasoline or diesel engines) with a crankshaft starter generator (CSG) integrated into the automatic transmission, the electric motor is to be actively used in the future to reduce engine roll. In the planned concept, the respective angle calculations are performed in two control units, the combustion engine control unit and the electric machine control unit, which are connected via a comparatively slow bus. The German patent application 10 2020 112 471 mentioned above, for example, deals with this.

[0015] Since (if) the electric motor does not have an absolute angle sensor to detect the electric motor's angular position, one of the several (for example, 10) similar poles of the electric motor must be selected as the reference pole via software. Under certain circumstances, this reference becomes invalid and must be detected and corrected in the combustion engine control unit for error-free operation. This is the subject of the present invention.

[0016] The rotor position sensor of the electric machine used according to the invention only detects the angular position relative to two poles of the electric machine. In particular, when using an electric machine as a damper for the internal combustion engine, the angle reference to the working cycle of the internal combustion engine must be known. An additional sensor for absolute angle detection is to be eliminated. Therefore, the invention describes a software solution (computer program product in the internal combustion engine control unit and / or electric machine control unit). The software solution according to the invention takes into account the fact that the calculation of the rotor position angle may be based on an incorrect reference point, in particular the reference pole, and may therefore be invalidated, which cannot be detected in the electric machine control unit.

[0017] Using a learning function according to the invention, the angular relationship between the electric motor and the combustion engine's working cycle is determined, preferably during a first engine shutdown and / or immediately after synchronization upon engine start, in the form of an initial mechanical angular relationship between the combustion engine and the electric motor. The exact procedure for this learning function will be discussed in more detail below.

[0018] Using an inventive calibration function, the initial mechanical angle reference between the two control units is calibrated in the electric motor control unit and / or the combustion engine control unit during each subsequent start and / or shutdown process and divided into two components: a "large component" in the so-called "pole shifts" (i.e., multiples of the geometric angle between two poles) and a "small component" that represents inaccuracies or disturbances in the angular position detection (scattering, play, tension in the engine / transmission drive train). The small component is averaged to increase accuracy and / or to dampen outliers caused by disturbances, resulting in a comparatively slow adaptation of the mechanical angle reference. The pole shifts or the number of pole shifts are immediately taken into account in the control.

[0019] Boundary conditions for the learning function: As soon as the internal combustion engine has synchronized, it detects the angular position of the combustion engine relative to the so-called firing TDC (TDC = top dead center) of a first cylinder in a known manner. This is used as the preferred reference mark. Synchronization takes place during start-up via a crankshaft sensor (e.g. an inductive increment sensor via a pole wheel with 58 teeth and a tooth gap consisting of two missing teeth) and a camshaft sensor. When the internal combustion engine and its control unit are switched off, this angular position of the combustion engine is lost. The angular resolution, for example, via the conventional pole wheel, is 6 degrees. General note: In four-stroke engines, a distinction is made between the gas exchange TDC between the exhaust and intake strokes and the firing TDC between the compression and power strokes. The top dead center of the piston of a first cylinder serves as the reference for the crankshaft position.The combustion engine's angular position thus determines the absolute crankshaft position at ignition TDC (ITDC). For the invention, this absolute combustion engine angular position when the combustion engine is stationary is relevant. In the electric machine control unit (also called the inverter control unit), there is no absolute angular reference for determining the rotor position. A rotor position sensor (RLS) provides a high-resolution angle measurement (0.1 degrees) between the (e.g., 10) poles of the rotor. The poles are equivalent; there is no absolute, fixed reference point or reference pole. The rotor position sensor continuously records the angle between the poles.

[0020] According to the invention, at each start-up, one pole is initially selected by software in the electric machine control unit as the reference point or reference pole. From this point on, the electromechanical electric machine's angular position is summed relative to this reference point or reference pole and reset to zero after 359 degrees.

[0021] If the electric machine and thus the electric machine control unit is switched off, the current electromechanical angular position to the initial reference pole is stored in the non-volatile memory (NVRAM) of the electric machine control unit when the electric machine is stopped and read out again at the next start and, if necessary, also made available to the combustion engine control unit.

[0022] On the other hand, this relative electromechanical electric machine angular position when the electric machine is stationary is relevant for the invention.

[0023] This electromechanical angle can be sent cyclically, for example in 200ms intervals, via the data bus from the electric machine control unit to the combustion engine control unit. How the learning function works:

[0024] The following is a further description of the particularly advantageous method of determining the mechanical angular relationship between the internal combustion engine and the electric motor according to the invention. This mechanical angular relationship is the geometric relationship between the internal combustion engine and the electric motor (which is constant during fault-free operation). It is preferably defined as the angular difference between, preferably, the ignition TDC (or another defined absolute crankshaft position of the internal combustion engine) as a reference mark and the initial reference point or reference pole of the electric motor. It is assumed that the electric motor control unit performs an error-free pole-related electromechanical angular position calculation.

[0025] For this purpose, this mechanical angle reference is initially calculated as part of a correspondingly programmed learning function (computer program product) in the combustion engine control unit and / or in the electric machine control unit, in particular when the engine is stopped for the first time, based on the above-described relative electric machine angular position when the electric machine is stationary and on the above-described absolute combustion engine angular position when the combustion engine is stationary, and stored in a non-volatile manner.

[0026] The learning function can also be triggered via the diagnostic interface after a workshop visit (e.g., if necessary, after the engine has been cranked or after the engine-gearbox assembly has been opened).

[0027] The calibration function has three tasks and is performed every time the motor stops (a reference pole is assumed as the reference point below): The accuracy of the mechanical angle reference between the combustion engine and the electric motor is to be improved by averaging deviations from the initial mechanical angle reference during each shutdown. Incorrect calculations of the mechanical angle reference resulting from an "incorrect" reference pole selected in the electric motor control unit are corrected by detecting so-called pole jumps or pole jump errors (rapid angle adjustment over multiples of 36 degrees with 10 poles). A "incorrect" reference pole is a selected reference pole that is not the initial reference pole. After a workshop visit without a diagnostic job to re-execute the learning function, an angle error of up to 18 degrees (or generally half the angle of adjacent poles) can occur, which is then slowly learned through averaging ("second adjustment portion" or "small portion," see above).Larger angular deviations are corrected "immediately" as pole shifts ("first adjustment portion" or "large portion", see above).

[0028] In a preferred development of the invention, the electromechanical angular position of the electric motor is read out and temporarily stored in the internal combustion engine control unit before the engine is started when the electric motor is stopped. The internal combustion engine control unit then counts the pulses from the increment encoder until the gap in the rotor or the ignition TDC is detected for the first time and memorizes this pulse count. After synchronization, the internal combustion engine control unit recalculates the crankshaft angle before the engine started based on the previously counted pulse count. As a result, the above-described internal combustion engine angular position with the internal combustion engine stopped is available retroactively immediately after the engine is started.Based on this calculated angular position of the combustion engine when the combustion engine is stopped and the temporarily stored electromechanical angular position of the electric machine when the electric machine is stopped, the mechanical angular reference between the electric machine and the combustion engine described above is calculated before the engine stops.

[0029] The invention is preferably used to enable excitation reduction by means of transmission-internal electric machine control in hybrid drives, for example with gasoline or diesel engines.

[0030] The invention will be described in more detail below using an exemplary embodiment. Fig. 1 schematically shows essential components and sizes of the entire motor-gearbox system and Fig. 2 a schematic representation of the mode of operation of the device according to the invention.

[0031] In Fig. 1 is a motor-gearbox assembly MGV in a hybrid vehicle with an internal combustion engine VM, an electric machine EM, an electric machine control unit EMS, a combustion engine control unit VMS and a communication bus B between the electric machine control unit EMS and the combustion engine control unit VMS. The motor-gearbox assembly MGV is housed in an engine-gearbox assembly housing MGV-G, which can also contain a dual-mass flywheel DMS, a torque converter clutch WK and a torque converter WD for an automatic transmission (transmission input torque M GET ). In particular, the internal combustion engine VM and the electric machine EM are connected to the motor-gearbox assembly housing MGV-G in a vibration-relevant manner. The electric machine EM can generate a total torque that consists of a basic drive torque and a torque that reduces the vibration excitations of the motor-gearbox assembly.For this purpose, knowledge of the mechanical angle reference between the combustion engine and the electric machine is required, the calculation of which is discussed below and demonstrated using . Fig. 2 is explained in more detail.

[0032] In Fig. 2 It is shown in more detail how, by appropriate design or programming of the electric machine control unit EMS and / or the combustion engine control unit, especially when the combustion engine VM and the electric machine EM are stationary, the mechanical angle reference of the combustion engine VM to the electric machine EM, i.e. the initial mechanical angle reference W_RP of the learning function or the averaged mechanical angle reference W_RP_mittel of the adjustment function, can be determined: In Fig. 1 and Fig. 2A first angular position detection function 1 for detecting an absolute combustion engine angular position KW with respect to the ignition TDC (ZOT) as a defined position marker and a second angular position detection function 2 for detecting a relative electric machine angular position RW with respect to a reference point—here preferably a reference pole, either the initial reference pole RP or a later new reference pole RP'—are schematically shown. The initial reference pole RP is a reference pole initially detected during a learning function after a first start. A reference pole is generally the first pole of several similar rotor poles selected by the electric machine control unit EMS, in this case 10 poles.

[0033] According to the invention, when the combustion engine VM and the electric machine EM are stationary, the absolute combustion engine angular position KW_stop is detected by the combustion engine control unit VMS, and the relative electric machine angular position RW_stop is detected by the electric machine control unit EMS. The EMS and VMS control units cyclically exchange data via bus B. In at least one of the VMS and EMS control units, a mechanical angular reference W_RP or W_RP_mittel of the combustion engine VM to the electric machine EM is determined and stored as the angular difference between the position mark ZOT and the initial reference pole RP based on these angular positions RW_stop and KW_stop.

[0034] Preferably, the mechanical initial angle reference W_RP is determined at a first start or stop of the combustion engine VM and the electric machine EM in the sense of a learning function relative to the initial reference pole RP.

[0035] In a further development of the invention, at each subsequent start after the first start of the internal combustion engine VM, the reference pole RP stored in a non-volatile memory (e.g., in an NVRAM) is selected in the electric motor EM. However, in the event of a fault, this reference pole may not be the actual reference pole, but rather another pole, which is then geometrically recognized as the first pole. This pole is referred to as the new reference pole RP'.

[0036] Explanation: The last reference pole is stored in the electric motor control unit when the control unit "goes to sleep." When the control unit "wakes up," the stored reference pole is read out and calculations continue from this pole, which may actually be a new reference pole RP'. As long as the crankshaft-electric motor assembly has not rotated further during the "sleep" state, no pole shift will occur. If the NVRAM value cannot be read out, or if the crankshaft or electric motor has continued to rotate, the electric motor control unit assumes the initial reference pole RP. In reality, however, it is the new reference pole RP', which is corrected by the inventive adjustment function based on detected pole shifts.

[0037] A learning function is followed by a calibration function, whereby the current mechanical angle reference W_RP or W_RP_average (old) is calibrated with each subsequent start and / or stop of the combustion engine VM and the electric motor EM. A first and a second calibration component are calculated in the combustion engine control unit VMS. A first calibration component W_PS represents the pole shifts PS, e.g., in the form of the number of pole shifts, between the initial reference pole RP and the new reference pole RP'. Furthermore, a second calibration component W_RP_average (new) represents the mean value between the current mechanical angle reference W_RP i (=W_RP or W_RP_average (old)) and the newly calculated mechanical angle reference W_RP i+1 =W_RP'-W_PS. W_RP' is the initially "incorrectly" determined angle difference between the ZOT and the new reference pole RP' if this is not the same as the initial reference pole.

[0038] The calibration function can be performed every time the combustion engine VM and the electric machine EM are stopped after a learning function.

[0039] In an advantageous embodiment of the invention, however, the calibration function in the combustion engine control unit VMS can also be performed immediately after the combustion engine VM is started. Prior to the combustion engine VM starting, the electromechanical electric machine angular position RW_stop is temporarily stored when the electric machine EM is stationary, the pulses of the crankshaft sensor are counted until the defined position mark ZOT is detected, and the combustion engine angular position KW is recalculated based on the counted number of pulses before the engine starts. Based on this recalculated combustion engine angular position KW_stop when the combustion engine VM is stationary and on the temporarily stored electromechanical electric machine angular position RW_stop when the electric machine EM is stationary, the mechanical angle reference W_RP or W_RP_mittel can be calculated even before a stop.

Claims

1. Angle position detection device in a hybrid vehicle equipped with an internal combustion engine (ICE) and an electric machine (EM), comprising a crankshaft sensor for detecting an absolute internal combustion engine angle position (KW) with respect to a defined position marker (TDC), a rotor position sensor for detecting a relative electric machine angle position (RW) with respect to a reference point in the form of a reference pole (RP; RP') from several identical rotor poles, and at least one electronic control unit (EMS, VMS) such that the absolute internal combustion engine angle position (KW_stop) and the relative electric machine angle position (RW_stop) are detected when the internal combustion engine (ICE) is stationary or at least slowly rotating and when the electric machine (EM) is stationary or at least slowly rotating, and that based on these angle positions (RW_stop, KW_stop), a mechanical angle reference (W_RP; W_RP_mean) of the internal combustion engine (ICE) to the electric machine (EM) is determined and stored as an angle difference between the position marker (TDC) and an initial reference point (RP), wherein at each subsequent start and / or stop of the internal combustion engine (ICE) and the electric machine (EM), the current mechanical angle reference (W_RP; W_RP_mean) is adjusted according to a learning function, characterized in that a first adjustment component (W_PS) represents the pole jumps (PS) between the initial reference pole (RP) and the new reference pole (RP'), and that • a second adjustment component represents the newly calculated mechanical angle reference (W_RPi+1) taking into account the first adjustment component (W_PS), or that • a second adjustment component represents the mean value between the current mechanical angle reference (W_RP_mean) and the newly calculated mechanical angle reference (W_RPi+1) taking into account the first adjustment component (W_PS).

2. Angle position detection device according to claim 1, characterized in that during a first stop of the internal combustion engine (ICE) and the electric machine (EM), a mechanical initial angle reference (W_RP) related to the initial reference point, which can be an initial reference pole (RP), is determined in the sense of a learning function.

3. Angle position detection device according to one of the preceding claims, characterized in that at each subsequent start after a first start of the internal combustion engine (ICE) and the electric machine (EM), the geometrically first recognized pole is selected as the new reference pole (RP') assuming it to be the initial reference pole (RP).

4. Angle position detection device according to one of the preceding claims, characterized in that the adjustment function is performed at each stop of the internal combustion engine (ICE) and the electric machine (EM) according to a learning function.

5. Angle position detection device according to one of the preceding claims, characterized in that the adjustment function is performed in the internal combustion engine control unit (VMS) immediately after a start of the internal combustion engine (ICE) by temporarily storing the electromechanical electric machine angle position (RW_stop) with the electric machine (EM) stationary before starting the internal combustion engine (ICE), counting the pulses of the crankshaft sensor until the defined position marker (TDC) is recognized, and based on the counted pulse number, back-calculating the internal combustion engine angle position (KW) before the engine start, to finally calculate the mechanical angle reference (W_RP; W_RP_mean) between the electric machine (EM) and the internal combustion engine (ICE) even before a stop, based on this back-calculated internal combustion engine angle position (KW_stop) with the internal combustion engine (ICE) stationary and on the temporarily stored electromechanical electric machine angle position (RW_stop) with the electric machine (EM) stationary.

6. Hybrid vehicle with a device according to one of the preceding claims 1 to 5.