Device for operating and determining the operating state of an electromagnetic actuator, as well as coupling device and motor vehicle drivetrain

Abstract

Device for operating and determining an operating state, in particular an actuator temperature and / or an actuator position, of an electromagnetic actuator (1), in particular a linear actuator, wherein a two-point controller (12) for operating the actuator (1) and a detection means (11C) configured to determine a time course of the control signal (H1) output by the two-point controller (12) and to determine the operating state from this, is provided, characterized in that the two-point controller is configured to reduce power for operating the actuator when an actuator temperature exceeds a limit value, so that continued operation of the device with reduced input power is possible.

Description

[0001] The invention relates to a device for operating and determining the operating state of an electromagnetic actuator. The invention also relates to a coupling device comprising a coupling means for selectively mechanically connecting and disconnecting two components, and an electromagnetic actuator for actuating the coupling. The invention further relates to a motor vehicle powertrain with such a coupling device.

[0002] Electromagnetic actuators are used to perform positioning tasks, for example, to actuate clutches in automotive transmissions. Knowing the current actuator position (the position the actuator occupies) is often crucial for control strategies and safety concepts. Furthermore, knowing the actuator's temperature is frequently necessary, for example, for condition monitoring. External sensors are often used for this purpose. However, the complexity of external sensors is high. They require installation space, integration is difficult, wiring must be considered, and the sensor signal typically needs to be converted into a digital signal. Moreover, the tolerances of the components involved introduce inaccuracies. By utilizing so-called inherent measurement effects within electromagnetic actuators, external sensors can be eliminated.

[0003] Methods for the inherent state detection of electric motors are well-known. Solutions for state detection in electromagnetic linear actuators or similar magnetic actuators are less widely known. For these actuators, external displacement measuring systems or proximity sensors are therefore usually used to detect the actuator position.

[0004] The concept of inherent position detection proposed in DE 102005018012 A1 is based on the choke coil principle. The concept proposed in DE 102007034768 B3 uses so-called hysteresis amplification.

[0005] DE 101 39 243 A1 discloses a method for monitoring an electromagnetically operated actuator with a first control unit controlled coil for actuating the actuator.

[0006] US 5914 849 A discloses a control circuit of a DC actuator.

[0007] DE 10 2007 034 768 B3 shows an electric lifting magnet, wherein, in the case of a pulsed current supply to the lifting magnet, the pulse frequency correlates with the lifting position of the lifting magnet.

[0008] The object of the present invention is to improve the state of the art.

[0009] This problem is solved by the features specified in the main claims. Preferred embodiments thereof are described in the dependent claims.

[0010] Accordingly, a device for operating an electromagnetic actuator and determining its operating state is proposed. The device comprises a two-position controller for operating the actuator and a determination mechanism. This mechanism is designed to determine the temporal profile of a control signal output by the two-position controller and to derive the operating state from this profile. In particular, the dynamics of the control signal are determined for this purpose.

[0011] The device is designed to supply an electric current, hereinafter also referred to as "actuator current," to the actuator based on the control signal. Corresponding to the temporal profile of the control signal, a characteristic temporal profile of the actuator current develops. This profile inherently contains the operating state of the actuator, as it essentially determines the rate at which the actuator current builds up and falls away, as well as its maximum and average magnitude.

[0012] It has now been recognized that, due to the characteristic control behavior of a two-point controller, the operating state of the actuator is also reflected in the control signal itself. The temporal profile of the actuator current is, in fact, reflected in the control signal. The invention utilizes this finding and accordingly uses the control signal of the two-point controller to deduce the operating state of the actuator very simply and accurately.

[0013] The electromagnetic actuator is, in particular, an electromagnetic linear actuator. The electromagnetic actuator can, in particular, have at least one or exactly one coil. This coil(s) allows the actuator's armature to be magnetically moved. This movement can be detected at the actuator and used mechanically as a positioning movement of the actuator. The actuator position corresponds to the position of the armature within the actuator or to a position that the actuator assumes externally. The device allows, in particular, the actuator temperature and / or the actuator position to be determined. These then constitute the desired operating state of the actuator.

[0014] The proposed concept offers the advantage that only minimal resources are needed to obtain information about the actuator's current operating state. This information can be immediately processed, for example, to control or regulate the actuator. By utilizing the actuator's integrated sensor capabilities, the tolerance chain can be shortened compared to the external sensors typically used.

[0015] Preferably, the two-point controller is an analog two-point controller. This can be, in particular, a discrete, i.e., hardware-implemented, two-point controller. With sufficiently fast hardware, the analog two-point controller can also be implemented as a software module, for example, within a control unit or other microcontroller.

[0016] Preferably, the two-point controller is predefined with an upper and a lower current limit, which it uses to limit the actuator current. The two-point controller also includes, in particular, a comparator circuit and an RS flip-flop (reset-set flip-flop). The two-point controller then uses the comparator circuit and the RS flip-flop to toggle the actuator current between the current limits, i.e., the actuator current fluctuates between the current limits. The current limits can, for example, be predefined to the two-point controller by a microcontroller.

[0017] Within the two-position controller, the current actuator, which can be measured, for example, is compared to the predefined current limits. If the upper limit is exceeded, the actuator is switched off. If the lower limit is undershot, the actuator is switched on. The signal output by the RS flip-flop for starting and stopping the actuator's current is preferably used as the control signal for a bridge driver in a bridge circuit, particularly an H-bridge. This bridge circuit then provides the actuator current. The outputs of the bridge circuit are therefore electrically connected to the inputs of the actuator, specifically the actuator's coil. The bridge driver controls the bridge circuit according to the control signal.This in turn causes the actuator to be supplied with a corresponding electrical current. This results in the temporal profile of the actuator current.

[0018] By specifying the upper and lower current limits, a current band is defined within which the actuator operates. This current band results in a characteristic dynamic of current rise and fall, which contains information about the actuator's operating state, particularly its position and temperature. The key finding is that this dynamic can be extracted from the frequency (or period) and the duty cycle (also called duty factor or DC), i.e., the ratio of the on-time to the switching period, of the control signal output by the two-position controller. Therefore, the diagnostic tool can deduce the actuator's operating state from the frequency (or period) and the duty cycle (or DC) of the control signal.

[0019] The detection device, for example, has a so-called capture input, which it uses to tap the control signal from the two-point controller. Such a capture input is an input, for example on a microprocessor, that can determine the switching times of binary signals with high accuracy. The control signal is, in particular, a PWM signal (PWM = pulse-width modulated).

[0020] The measuring device can be configured to determine the duty cycle of the control signal and, from this duty cycle, to calculate the actuator temperature. An additional temperature sensor is therefore not required. The actuator temperature determined in this way reflects the temperature of the actuator coil. This is because the coil's electrical resistance changes depending on the temperature and the material. With conductor materials commonly used in coils, such as copper, the electrical resistance increases with rising temperature. To provide a specific, required actuator current at a constant supply voltage, the duty cycle must therefore be adjusted to the actuator temperature. Thus, a high actuator temperature requires a comparatively long duty cycle, while a low actuator temperature requires a comparatively short duty cycle to provide the same actuator current.Therefore, there is a clear correlation between the duty cycle and the actuator temperature. Thus, the actuator temperature can be determined based on the duty cycle or, equivalently, the duty cycle.

[0021] The actuator temperature determined by the measuring device (11C) is used to change the electrical power supplied to the actuator. Thus, at a relatively high actuator temperature, the electrical power supplied to the actuator is specifically reduced.

[0022] The detection tool can also be designed to determine the frequency of the control signal and the actuator current, as well as to determine the actuator's position from the frequency and the actuator current. Thus, the actuator position can be easily determined.

[0023] Preferably, the detection method is also designed to include the current supply voltage of the actuator when determining the operating state. Normally, the supply voltage is essentially constant. In this case, changes in the supply voltage do not need to be specifically considered when determining the operating state. However, in some cases, the supply voltage can fluctuate. Then it is advantageous to take this into account when determining the operating state.

[0024] The determination tool preferably includes at least one lookup table, a characteristic map, or another function and is designed to determine the operating state from the control signal. In particular, the relationship between duty cycle and actuator temperature, as well as the relationship between actuator position, actuator current, and frequency, can each be stored in a lookup table, a characteristic map, or another function. The dependence on the supply voltage can then be stored as a further factor in the lookup table, characteristic map, or other function. The lookup table, characteristic map, or other function can, in particular, have been determined empirically beforehand or pre-defined using model calculations.

[0025] By using a highly electrically conductive material, such as aluminum or copper, in specific areas of the actuator, the dependence of the actuator's current build-up dynamics on the operating state can be optimized for monitoring purposes. This is due to the fact that the proposed method / device essentially evaluates position-dependent eddy current effects within the actuator. In particular, it has therefore proven advantageous to equip the actuator's armature and / or magnetic yoke with a highly electrically conductive eddy current ring, for example, made of a copper or aluminum alloy.

[0026] Furthermore, a coupling device is proposed, comprising a coupling element for the selective mechanical connection and disconnection of two components, and an electromagnetic actuator for moving the coupling element. The coupling device incorporates the proposed mechanism for operating and determining the operating state of the actuator. Therefore, no additional sensors are required to determine the actuator's operating state.

[0027] The two components could be, for example, shafts. One component can be fixed and the other movable relative to it, for example, rotatable or displaceable. Furthermore, both components can also be rotatable or displaceable relative to each other when uncoupled. The coupling element movable by the actuator could be, for example, a coupling sleeve, a coupling disc, or a coupling pressure plate.

[0028] The coupling device can be, in particular, a coupling device of a motor vehicle powertrain, for example, for a passenger car or truck. The coupling device can, for example, be implemented in or for a motor vehicle transmission. Such a motor vehicle powertrain with such a coupling device is therefore also proposed.

[0029] In addition to those already mentioned, the proposed device may have the following variations or advantages: • The hardware logic (analog two-point controller) can be implemented in software at a fast sampling rate (FPGA, DSP, fast µC). • The upper and lower current limits can be varied, for example to bring the operating frequency into targeted, advantageous ranges and / or to keep it constant there. • By specifying the current limits, a robust current regulator is simultaneously implemented. This means that the current flowing through the actuator coil (except in the case of very fast movements of the actuator, which usually only occur briefly due to the practically limited actuator stroke) always remains within the tolerance band defined by the lower and upper limits. • The use of the analog two-point controller also implies an overcurrent shutdown. • The actuator's sensitivity can be optimized to determine its operating state more accurately. For example, targeted model-based development of the actuator using FEM simulation is possible. • The determined operating states of the actuator can be compared with expected operating states or intervals of tolerable operating states. This allows, for example, monitoring of the actuator for malfunctions or wear (diagnostics or condition monitoring). • The determined actuator temperature can be used to switch off the actuator before overheating occurs. • According to the invention, before overheating is reached, the electrical power supplied to the actuator is successively reduced, thus enabling continued operation at reduced power. This prevents overheating (so-called derating function).

[0030] The invention is explained in more detail below with reference to figures, from which further preferred embodiments and features of the invention can be derived. These figures are shown schematically: Fig. 1 an electromagnetic actuator with a coupling device, Fig. 2 a system for operating an electromagnetic actuator, Fig. 3 a characteristic curve for determining an actuator position, Fig. 4 another characteristic map.

[0031] The electromagnetic actuator 1 according to Fig. Actuator 1 serves to move a coupling element 7 in a coupling device 2. Actuator 1, for example, has a single magnetic coil 3 and a linearly movable armature 4. Actuator 1 is therefore a linear actuator. The mobility of the armature 4 is illustrated by the double arrow. By energizing the coil 3, a magnetic force can be exerted on the armature 4, which pushes the armature 4 towards the coil 3. A restoring force acting against the magnetic force can be applied, for example, by a spring. The position of the armature 4 in actuator 1 then depends on the magnitude of the magnetic force and the restoring force.

[0032] An eddy current ring 5 can optionally be fixed to the anchor 4. This ring is made of an electrically conductive material, for example a copper or aluminum alloy.

[0033] The coil 3 is fixedly mounted in a housing 6. The armature 4 is guided within the housing 6 so that it can move at least linearly. The armature 4 acts on the coupling element 7, which in this example is designed as a coupling sleeve. At least the linear movement of the armature 4 is thus transmitted to the coupling element 7. The coupling element 7 therefore moves linearly with the armature 4. A rotational decoupling mechanism can be provided between the armature 4 and the coupling element 7, which prevents any rotation of the coupling element 7 from being transmitted to the armature 4.

[0034] The coupling means 7 is designed to selectively connect and disconnect two components 8 and 9 mechanically. In a first position of the coupling means 7, the components 8 and 9 are therefore mechanically coupled to each other, and in a second position of the coupling means 7, the components 8 and 9 are therefore mechanically separated from each other. The components 8 and 9 are, for example, shafts that are rotatable relative to each other in the separated state and can only be rotated together in the coupled state. For this purpose, they are rotatably mounted in the housing 6 by suitable bearing means 10, for example, rolling bearings. One axis of rotation of the components 8 and 9 is designated by the reference numeral L.

[0035] The in Fig. The coupling device 2 shown in Figure 1 is preferably used in a motor vehicle drivetrain, such as a motor vehicle transmission, for the selective mechanical connection and separation of two shafts. The housing 6 can then, for example, be a transmission housing.

[0036] The position of the armature 4 in the actuator 1 (= actuator position) directly determines the position of the coupling element 7, and thus also the coupling state of the coupling device 2. To determine the current actuator position, additional sensors can be used. External sensors can also be used to determine the actuator temperature. However, as mentioned earlier, this approach has disadvantages. Therefore, it is desirable to be able to determine the operating state of the actuator 1, in particular its actuator position and its actuator temperature, using existing means.

[0037] Fig. Figure 2 shows a system for operating an electromagnetic actuator 1, such as the one from Fig. 1. The system has a microcontroller 11.

[0038] Furthermore, an analog two-point controller 12 and a bridge driver 13 are provided. A bridge circuit 14 is also provided. This serves to supply electrical power to the actuator 1. The actuator 1 is in Fig. Figure 2 is represented as an equivalent circuit diagram in electrical engineering, consisting of a network of ohmic resistors and inductors. Elements 11, 12, 13, and 14 of the system have corresponding inputs and outputs, each of which is connected in Fig. 2 are shown and labelled.

[0039] The microcontroller 11 has, for example, two modules 11A and 11B. These can be implemented as software or hardware modules. Module 11A contains, in this case, a higher-level control logic. Module 11A therefore contains, for example, control functions, such as, in particular, functional software. Module 11B contains a target current determination unit with a current regulator, an actual current conditioning unit, and a detection device 11C for determining the operating state of actuator 1. Module 11B therefore contains, for example, basic functions, such as, in particular, basic software.

[0040] The electrical current underlying the setpoint current determination, the current controller, and the actual current conditioning is the actuator current, i.e., the electrical current supplied to actuator 1 via the bridge circuit 14. The setpoint current determination with current controller determines a required electrical current for actuator 1 (setpoint current; setpoint-actuator current). The actual current conditioning prepares the electrical current currently supplied to actuator 1 (actual current; actual-actuator current) for processing in the microcontroller 11 and makes it available for the setpoint current determination with current controller and the measurement device 11C.

[0041] The target current determination with current controller transmits corresponding control signals, in Fig. The outputs 2, designated as "PWM-Out 1" and "PWM-Out 2", are connected to the analog two-position controller 12. The two-position controller consists of a comparator circuit 12A and an RS flip-flop 12B. The two-position controller 12 is implemented here as a discrete hardware circuit. Alternatively, provided a sufficiently fast sampling rate is available, it can also be implemented as a software module, in particular of the microcontroller 11.

[0042] The two-position controller 12 toggles, or fluctuates, the actuator current between defined current limits using the comparator circuit 12A and the RS flip-flop 12B. These current limits, specifically a lower and an upper current limit, are specified by the microcontroller 11. The two-position controller 12 compares the current actuator current (actual actuator current) with the specified current limits. For this purpose, the current actuator current is supplied to the two-position controller 12. If the upper limit is exceeded, the actuator is de-energized (current off); if the lower limit is undershot, the actuator is energized (current on). The signals for energizing and de-energizing the actuator are output as control signals H1 and H2 from the two-position controller 12 to the bridge driver 13. By specifying the current limits, both a current controller and an overcurrent protection device are implemented simultaneously.

[0043] The bridge driver 13 controls the bridge circuit 14. This circuit supplies electrical current to the actuator 1 according to the control signals H1 and H2. The actuator 1 can be temporarily energized (current on) and de-energized (current off) by intermittently applying a supply voltage. In this example, the bridge circuit is configured as an H-bridge circuit. Accordingly, the bridge driver 13 has one driver for each bridge branch. These drivers are in Fig. 2 referred to as the “H1 driver” and “H2 driver”.

[0044] In the area of ​​bridge circuit 14, means are also provided by which the currently applied actuator current (actual actuator current) and the currently applied supply voltage of actuator 1 can be measured or otherwise determined. Fig. These means are referred to as "current measurement" and "voltage measurement". The current actuator current is fed, among other things, to the two-point controller 12, specifically to the comparator circuit 12A, so that the actuator current is kept within the specified current limits, as described above.

[0045] By specifying the upper and lower current limits, a predetermined current band is established within which the actuator current remains, i.e., within which the actuator operates. Within such a predetermined current band, a characteristic dynamic of current build-up and decay results. Fig. Figure 2 shows an example of such current build-up and current decay within the block of the comparator circuit 12A.

[0046] Information about the operating state of actuator 1, in particular its position and temperature, is implicitly contained in this dynamic. Due to the specific control characteristics of the two-point controller 12, this dynamic is also reflected in its control signals H1 and H2. It can therefore be extracted from the frequency and duty cycle of the control signals H1 and H2. At least one of the control signals H1 or H2 is thus supplied to the microcontroller 11 via a capture input. Fig. 2. This is the control signal H1. The capture input is in Fig. 2 is designated as “PWM-In 1”. The tap for the control signal H1 is located, for example, at the respective output of the RS flip-flop 12B or the two-position controller 12 (in Fig. 2 at its upper exit).

[0047] The control signal H1 is fed to the investigative device 11C via the capture input of the microcontroller 11. Additionally, the investigative device 11C receives a signal via another input of the microcontroller 11 (in Fig. The currently applied supply voltage is supplied to module 2 (referred to as "ADC-In 2"). As explained above, the detection device 11C also receives the current currently supplied to the actuator (actual actuator current) from the actual current conditioning of module 11B.

[0048] To determine the operating state based on the incoming information / signals, the detection device 11C has one or more characteristic curves. It is designed to determine the operating state of the actuator using these curves.

[0049] Examples of such characteristic maps are Fig. 3 and Fig. Four examples can be found. These may, for instance, have been determined empirically beforehand.

[0050] Fig. Figure 3 shows a characteristic curve by which the measuring device 11C can determine the actuator position ("position, mm") based on the actuator current ("current, A") and the frequency of the control signal H1 ("frequency, Hz"). This allows exactly one unique actuator position to be assigned to each pair of current and frequency values.

[0051] Different supply voltages can result in different assignments of current, frequency, and actuator position. Therefore, if the supply voltage remains essentially constant, it does not need to be considered further in determining the operating state. However, if it fluctuates, it may be necessary to provide several such characteristic curves for different supply voltages or supply voltage ranges.

[0052] Fig. Figure 4 shows several characteristic curves for different supply voltages (between 36V and 56V), which the detection device 11C uses to determine the actuator position ("Position, mm") based on the actuator current ("Current, A") and the duty cycle of the control signal H1 ("DutyCycle, %"). This allows each pair of current and duty cycle values ​​to be uniquely assigned to exactly one actuator position for a supply voltage between 36V and 56V. The uppermost characteristic curve in Fig. 2 forms the one for the supply voltage in the range of 36V and the lowest characteristic curve in Fig. 2 represents the supply voltage in the range of 56V.

[0053] Corresponding characteristic curves can be provided for the actuator temperature, either alternatively or additionally, which is determined in particular by the duty cycle and the supply voltage. Such a characteristic curve illustrates the unambiguous relationship between the actuator temperature and the duty cycle.

[0054] According to the system Fig. In addition to the explicitly described or named components, optional filters 15 may be provided. The elements 16 each represent an optional signal conditioning for the two-point controller 12. Reference sign 1 Electromagnetic actuator 2 coupling device 3 magnetic coil 4 anchors 5 Eddy current ring 6 cases 7 Coupling device, coupling sleeve 8 Component, shaft 9 Component, shaft 10 Storage equipment 11 microcontrollers Modules 11A and 11B 11C Investigative tools 12 Analog two-point controller 12A comparator circuit 12B RS flip-flop 13 bridge drivers 14 Bridge circuit 15 filters 16 Signal processing H1, H2 control signal L axis of rotation

Claims

Device for operating and determining an operating state, in particular an actuator temperature and / or an actuator position, of an electromagnetic actuator (1), in particular a linear actuator, wherein a two-point controller (12) for operating the actuator (1) and a detection means (11C) configured to determine a time course of the control signal (H1) output by the two-point controller (12) and to determine the operating state from this, is provided, characterized in that the two-point controller is configured to reduce power for operating the actuator when an actuator temperature exceeds a limit value, so that continued operation of the device with reduced input power is possible. Device according to claim 1, wherein the two-point controller (12) is an analog two-point controller. Device according to claim 2, wherein the two-point controller (12) is implemented discretely in hardware. Device according to one of the preceding claims, wherein the two-point controller (12) is provided with an upper current limit and a lower current limit by which it limits the electric current supplied to the actuator (1). Device according to one of the preceding claims, wherein the determining means (11C) is configured to determine a value of the duty cycle and duty cycle of the control signal (H1) and to determine an actuator temperature from the one value of duty cycle and duty cycle. Device according to one of the preceding claims, wherein the determining means (11C) is configured to determine a value of frequency and period of the control signal (H1) as well as to determine the electric current supplied to the actuator (1) and to determine an actuator position (1) from a value of the frequency and period as well as from the current. Device according to one of the preceding claims, wherein the determining means (11C) is configured to include a supply voltage of the actuator (1) in the determination of the operating state. Device according to one of the preceding claims, wherein the detection means (11C) comprises a lookup table or a characteristic map or another mathematical function and is configured to determine the operating state of the actuator (1) herewith and with the control signal (H1). Coupling device (2) with a coupling means (7) for selectively mechanically connecting and disconnecting two components (8, 9) and an electromagnetic actuator (1) for moving the coupling means (7), characterized by a device for operating and determining an operating state of the actuator (1) according to one of the preceding claims. Motor vehicle powertrain characterized by a coupling device (2) according to claim 9 .

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