WO2018082949A1

WO2018082949A1 - Device for operating and for determining an operating state of an electromagnetic actuator, clutch device, and motor vehicle drive train

Info

Publication number: WO2018082949A1
Application number: PCT/EP2017/076942
Authority: WO
Inventors: Florian WEINL; Martin Ruider; Michael Pantke; Thomas Speh; Thomas Schwegler; Lothar Kiltz
Original assignee: Zf Friedrichshafen Ag
Priority date: 2016-11-02
Filing date: 2017-10-23
Publication date: 2018-05-11
Also published as: DE102016221477A1

Abstract

The invention relates to a device for operating and for determining an operating state of an electromagnetic actuator (1). The device has a two-position controller (12) for operating the actuator (1) and a determining means (11C). The determining means (11C) is designed to determine a course over time of the actuation signal (H1) output by the two-position controller (12) and to establish the operating state therefrom. The invention also relates to a clutch device (2) having a device of this type and to a motor vehicle drive train having a clutch device (2) of this type.

Description

Device for operating and determining an operating state of an electromagnetic actuator and coupling device and motor vehicle drive train

The invention relates to a device for operating and for determining an operating state of an electromagnetic actuator. The invention also relates to a coupling device with a coupling means for selectively mechanically connecting and disconnecting two components and an electromagnetic actuator for actuating the coupling. The invention also relates to a motor vehicle drive train with such a coupling device.

Electromagnetic actuators are used to realize actuating tasks, for example for the actuation of clutches in motor vehicle transmissions. It is often of great importance to know the current actuator position (= positioning position, which the actuator occupies) for control strategies or safety concepts. In addition, it may often be necessary to know the temperature of the actuator, for example for condition monitoring. Frequently, external sensors are used. However, the cost of external sensors is high. For example, space is required, integration is difficult, cabling must be taken into account and normally the conversion of the sensor signal to a digital signal is required. In addition, the tolerance chain of the components involved leads to inaccuracies. By using so-called inherent measuring effects within electromagnetic actuators, external sensors can be dispensed with.

Methods for the inherent state detection of electric motors are known. Less widely known are solutions for state detection in electromagnetic linear actuators or comparable magnetic actuators. In these actuators, external position measuring systems or proximity sensors are therefore usually used to detect the actuator position.

The concept of an inherent position detection proposed in DE 102005018012 A1 is based on the choke coil principle. In the in the DE 102007034768 B3 proposed concept, the so-called hysteresis gain is used.

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

This object is achieved by the features specified in the main claims. Preferred embodiments thereof are the dependent claims.

Accordingly, a device for operating an electromagnetic actuator and for determining an operating state of the actuator is proposed. The device has a two-position controller for operating the actuator and a determination means. The determining means is designed to determine a time profile of a control signal output by the two-point controller and to determine therefrom the operating state. In particular, a dynamic of the drive signal is determined.

On the basis of the activation signal, the device is designed to supply the actuator with an electric current, also referred to below as "actuator current." A characteristic time profile of the actuator current is formed in accordance with the time profile of the activation signal, in which the operating state of the actuator is inherently contained because it essentially determines the speed with which the actuator current builds up and degrades again, as well as the maximum and average height of the actuator current.

It has now been recognized that due to the characteristic control of a two-level controller, the operating state of the actuator is also found in the control signal itself. The time course of the actuator current is reflected in the drive signal again. This finding makes use of the invention and accordingly adopts the control signal of the two-position controller in order to deduce from it very simply and precisely the operating state of the actuator.

The electromagnetic actuator is in particular an electromagnetic linear actuator. The electromagnetic actuator can in particular via have at least or exactly one coil. Through this coil (s), an armature of the actuator is magnetically movable. This movement can be tapped on the actuator and used mechanically as an actuating movement of the actuator. In this case, the actuator position corresponds to a position of the armature within the actuator or a positioning position which the actuator occupies externally. By means of the device, in particular, an actuator temperature and / or an actuator position of the actuator can be determined. These form accordingly the sought operating state of the actuator.

The proposed concept offers the advantage that only a few means need be used to obtain information about the current operating state of the actuator. This information can be processed immediately, for example, to control or regulate the actuator. By using the integrated sensor effects of the actuator, the tolerance chain can be shortened compared to normally used external sensors.

The two-position controller is preferably an analog two-position controller. In particular, this may be a discrete, ie hardware, two-position controller. With correspondingly fast hardware, the analog two-point controller can also be designed as a software module, for example a control device or another microcontroller.

Preferably, the two-position controller, an upper current limit and a lower

Current limit specified with which he limits the actuator current. The two-position controller also has in particular a comparator circuit and an RS flip-flop (= reset set flip-flop). The two-position controller then toggles the actuator current between the current limits using the comparator circuit and the RS flip-flop, i. the actuator current fluctuates between the current limits. The current limits can be predetermined for example by a microcontroller the two-step controller.

Within the two-point controller, the current actuator current, which can be measured, for example, compared with the predetermined current limits. If the upper limit is exceeded, then the energization of the actuator is terminated (= power off). And if it falls below the lower limit then the Activation of the actuator started (= power on). The output from the RS flip-flop signal for the start and the end of the energization of the actuator is preferably used as the drive signal for a bridge driver of a bridge circuit, in particular a so-called H-bridge circuit. This bridge circuit then serves to provide the actuator current. The outputs of the bridge circuit are thus accordingly electrically connected to the inputs of the actuator, in particular the coil of the actuator. The bridge driver controls the bridge circuit according to the drive signal. This in turn causes a corresponding electrical energization of the actuator with the actuator current. This results in the time course of the actuator current.

The specification of the upper and lower current limit results in a current band in which the actuator is operated. The current band results in a characteristic dynamics of the current and current breakdown, in which the information about the operating state of the actuator, in particular its position and temperature, is included. The finding is that this dynamics over the frequency or the period and the duty cycle or the duty cycle (also called duty-cycle or DC), ie the ratio of the duty cycle to the switching period, the output from the two-level control signal can be extracted. The determining means can thus close the operating state of the actuator from the frequency or period and the duty cycle or the duty cycle of the drive signal.

The determination means has, for example, a so-called capture input with which it picks up the drive signal from the two-position controller. In such a capture input is an input, for example in a microprocessor, with which the switching times of binary signals can be determined with high accuracy. The activation signal is, in particular, a PWM signal (PWM = pulse width modulation / pulse width modulation).

The determining means may be designed to determine a duty cycle of the drive signal and to determine the temperature of the actuator from the duty cycle. An extra temperature sensor is therefore not required. The thus determined actuator temperature reflects a temperature of the coil of the actuator again. This changes namely their temperature and material dependent their electrical resistance. With the conductor materials commonly used in coils, such as copper, the electrical resistance increases with increasing temperature. To be able to provide a specific, required actuator current under a constant supply voltage, the duty cycle must therefore be adapted 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 in order to provide the same actuator current. So there is a clear relationship 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.

The actuator temperature determined by the determining means (11 C) can be used to change the electric power supplied to the actuator. Thus, at a relatively high actuator temperature, the electric power supplied to the actuator can be selectively reduced.

The determining means can also be designed to determine a frequency of the drive signal and the actuator current, as well as to determine a position of the actuator from the frequency and the actuator current. Thus, the actuator position can be determined easily.

Preferably, the determining means is also designed to include a current supply voltage of the actuator in the determination of the operating state. Normally the supply voltage is essentially constant. Then changes in the supply voltage need not be taken into account when determining the operating state. In some cases, however, the supply voltage may fluctuate. Then it is advantageous to consider these in the determination of the operating state.

The determination means preferably has at least one look-up table, a map or another function and is accordingly designed to determine drive state from the drive signal. In particular, the relation between the switch-on duration and the actuator temperature as well as the relation between actuator position, actuator current and frequency can each be stored in a look-up table or a characteristic field or another function. As a further factor, the dependence on the supply voltage can then be stored in the look-up table or the characteristic field or the other function. The look-up table or the characteristic field or the other function may in particular have been determined empirically beforehand or have been determined in advance on the basis of model calculations.

By using a good electrically conductive material, such as aluminum or copper, in specific areas of the actuator, the dependence of the current build-up dynamics of the actuator on the operating condition can be optimized with respect to the operating state monitoring. This is due to the fact that the proposed procedure / device basically evaluates position-dependent eddy current effects within the actuator. In particular, it has therefore proved to be advantageous to provide the armature and / or the magnetic yoke of the actuator with a highly electrically conductive eddy current ring, for example of a copper or aluminum material.

It is also proposed a coupling device with a coupling means for selectively mechanically connecting and disconnecting two components and an electromagnetic actuator for moving the coupling means. The coupling device has the proposed device for operating and for determining the operating state of the actuator. Thus, no extra sensors are needed to determine the operating state of the actuator.

The two components may be, for example, waves. One of the components may be fixed and the other be movable relative thereto, for example rotatable or displaceable. In addition, both components in the non-coupled state relative to each other can be rotatable or displaceable. The coupling means movable by the actuator may be, for example, a coupling sleeve or a clutch disc or a clutch pressure plate. The coupling device may in particular be a coupling device of a motor vehicle drive train, for example for a passenger or truck. The coupling device can be realized for example in or for a motor vehicle transmission. Such a motor vehicle drive train with such a coupling device is therefore also proposed.

The proposed device may, in addition to those already mentioned have the following modifications or advantages:

• The hardware logic (analogue two-point controller) can be implemented in software with fast sampling rate (FPGA, DSP, fast μθ).

• The specification of the upper and lower current limit can be varied, for example to bring the working frequency in targeted, advantageous areas and / or to keep constant there.

• By specifying the current limits, a robust current controller is implemented at the same time. In other words, the current flowing through the actuator coil is always within the tolerance band specified by the lower and upper limit (except in the case of very fast movements of the actuator, which usually occur at most only briefly due to the practically limited actuator stroke).

• Using the analog two-point controller also implies an overcurrent shutdown.

• The actuator can be optimized with regard to its sensitivity in order to be able to determine the operating status more precisely. For example, a targeted model-based development of the actuator via FEM simulation is possible.

• The determined operating states of the actuator can be compared with expected operating states or intervals of tolerable operating states. In this way, it is possible, for example, to monitor the actuator for malfunctions or wear (diagnosis or condition monitoring).

• The determined actuator temperature can be used to switch off the actuator before overheating occurs.

• Before overheating is reached, the electrical power supplied to the actuator can be successively reduced, thus allowing further operation with reduced power in order to prevent overheating (so-called de- rating function). In the following the invention will be explained in more detail with reference to figures, from which further preferred embodiments and features of the invention can be removed. In each case show in a schematic representation:

1 shows an electromagnetic actuator with a coupling device,

2 shows a system for operating an electromagnetic actuator,

3 shows a characteristic diagram for determining an actuator position,

Fig. 4 shows another map.

1 serves to move a coupling means 7 in a coupling device 2. The actuator 1 has, for example, a single magnetic coil 3 and a linearly movable armature 4. The actuator 1 is thus a linear actuator. The mobility of the armature 4 is illustrated by the double arrow. By electrical energization of the coil 3, a magnetic force can be exerted on the armature 4, which urges the armature 4 in the direction of the coil 3. A restoring force acting against the magnetic force can be applied, for example, by a spring means. Depending on the magnitude of the magnetic force and the restoring force, the position of the armature 4 in the actuator 1 then results.

Stationary on the armature 4 may optionally be arranged a vortex flow ring 5. This consists of an electrically conductive material, for example of a copper or aluminum material.

The coil 3 is arranged stationarily in a housing 6. The armature 4 is guided in the housing 6 at least linearly movable. The armature 4 acts on the coupling means 7, which is exemplified here as a coupling sleeve. At least the linear movement of the armature 4 is thus transmitted to the coupling means 7. The coupling means 7 is thus moved linearly with the armature 4. There may be provided a rotational decoupling between armature 4 and coupling means 7, which prevents a rotation of the coupling means 7 is transmitted to the armature 4. The coupling means 7 is designed to connect two components 8, 9 optional mechanical and separate. In a first position of the coupling means 7, the components 8, 9 are therefore mechanically coupled to each other and in a second position of the coupling means 7, the components 8, 9 are therefore mechanically separated from each other. The components 8, 9 are exemplary here waves, which are rotatable relative to each other in the separated state and are rotatable only in the coupled state together. For this purpose, they are rotatably mounted in the housing 6 by corresponding bearing means 10, for example rolling bearings. An axis of rotation of the components 8, 9 is marked with the reference symbol L.

The coupling device 2 shown in Fig. 1 is preferably used in a motor vehicle drive train, such as a motor vehicle transmission, for the optional mechanical connection and separation of two waves. The housing 6 may then be, for example, a transmission housing.

The position of the armature 4 in the actuator 1 (= actuator position) directly determines the position of the coupling means 7, so also the coupling state of the coupling device 2. In order to determine which actuator position is currently applied, extra sensors can be used. Likewise, external sensors can be used to determine the actuator temperature. As already mentioned, however, there are disadvantages here. It is therefore 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.

FIG. 2 shows a system for operating an electromagnetic actuator 1, in particular that of FIG. 1. The system has a microcontroller 1 1. In addition, an analog two-point controller 12 is provided, as well as a bridge driver 13. Furthermore, a bridge circuit 14 is provided. This serves for electrical energization of the actuator. 1 The actuator 1 is shown in Fig. 2 as electrical equivalent circuit diagram, consisting of a network of resistors and inductances, shown. The elements 1 1, 12, 13, 14 of the system have corresponding inputs and outputs, which are each shown in FIG. 2 and designated. The microcontroller 1 1 has two modules 1 1 A, 1 1 B, for example. These can be designed, for example, as software modules or hardware modules. Module 1 1 A contains in this case a superimposed control logic. Module 1 1 A thus contains, for example, control functions, such as, in particular, a functional software. Module 1 1 B contains a desired current determination, which has a current regulator, an actual current processing and a determination means 1 1 C for determining the operating state of the actuator. 1 So module 1 1 B contains, for example, basic functions, such as in particular a basic software.

The electrical current underlying the desired current determination, the current controller and the actual current conditioning forms the actuator current, that is, the electric current supplied to the actuator 1 by the bridge circuit 14. By means of the setpoint current determination with current controller, a required electric current for the actuator 1 (setpoint current, setpoint actuator current) is determined. By means of the Iststromaufbereitung a current to the actuator 1 supplied electric current (actual current, actual actuator current) is processed for processing in the microcontroller 1 1 and the target current determination with current controller and the determining means 1 1 C provided.

The setpoint current determination with current controller transmits corresponding control signals, referred to in FIG. 2 as "PWM Out 1", "PWM Out 2", 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 constructed here as a discrete hardware circuit. Alternatively, assuming a sufficiently fast sampling rate, it can also be designed as a software module, in particular of the microcontroller 1 1.

The two-step controller 12 allows the actuator current with the help of the comparator 12A and the RS flip-flop 12B between defined current limits toggle, so fluctuate. These current limits, in detail a lower and an upper current limit, are specified by the microcontroller 11. In the two-position controller 12, the current actuator current (actual actuator current) is compared with the predetermined current limits. For this purpose, the current actuator current is supplied to the two-position controller 12. If the upper limit is exceeded, the current is withdrawn from the actuator (= power off), at one If the lower limit is undershot, the actuator is energized (= current on). The signal for the supply and Entstromung of the actuator is output as control signals H1, H2 from the two-point controller 12 to the bridge driver 13. By specifying the current limits thus simultaneously a current controller and an overcurrent shutdown are realized.

The bridge driver 13 operates the bridge circuit 14. By means of this, the actuator 1 is electrically energized in accordance with the drive signals H1, H2. In this case, the actuator 1 can be energized temporarily by pulsed application of a supply voltage (= current on) and temporarily discharged (= current off). In the present case, the bridge circuit is formed by way of example as an H-bridge circuit. Accordingly, the bridge driver 13 has a driver per bridge branch. These drivers are designated as "H1 drivers" and "H2 drivers" in FIG.

In the area of the bridge circuit 14, means are also provided by which the currently applied actuator current (actual actuator current) as well as the currently applied supply voltage of the actuator 1 can be measured or otherwise determined. In Fig. 2, these means are referred to as "current measurement" and "measurement voltage". Among other things, the current actuator current is supplied to the two-position controller 12, in detail to the comparator circuit 12A, so that the actuator current, as described above, is kept between the predetermined current limits.

The specification of the upper and lower current limit results in a predetermined current band, in which the actuator current resides, in which he actuator is thus operated. With such a predetermined current band results in a characteristic dynamics of current and current reduction. In Fig. 2, such current and current degeneration is exemplified within the block of the comparator circuit 12A.

The information about the operating state of the actuator 1, in particular the actuator position and the actuator temperature, is implicitly contained in this dynamic. This dynamic is also due to the special control characteristic of the two-level controller 12 in its drive signals H1, H2 again. So you can choose from the frequency and Duty cycle of the drive signals H1, H2 are extracted. The microcontroller 1 1 is therefore supplied with at least one of the drive signals H1, H2 via a capture input. In Fig. 2, this is the drive signal H1. The capture input is designated as "PWM-In 1" in FIG. 2. The tap for the drive signal H1 is located, for example, at the respective output of the RS flip-flop 12B or the two-point controller 12 (in FIG upper output).

The drive signal H1 is fed to the detection means 1 1 C via the capture input of the microcontroller 1 1. In addition, the currently applied supply voltage is supplied to the determination means 1 1 C via a further input of the microcontroller 1 1 (referred to as "ADC-In 2" in FIG. 2) As explained above, the determination means 1 1 C also receives from the actual current conditioning of the Module 1 1 B is the current supplied to the actuator (actual actuator current).

To determine the operating state based on the incoming information / signals, the determining means 1 1 C one or more maps on. It is designed to determine the operating state of the actuator so.

Examples of such maps are shown in FIG. 3 and FIG. 4 as an example. These may have been determined empirically in advance, for example.

3 shows a characteristic diagram by means of which the determination means 1 1 C can determine the actuator position ("position, mm") on the basis of the actuator current ("current, A") and the frequency of the drive signal H 1 ("frequency, Hz") Each value pair of current and frequency can be assigned exactly one actuator position.

Different supply voltages can result in different assignments of current, frequency and actuator position. Therefore, if the supply voltage is substantially constant, it need not be further included in the determination of the operating state. However, if this varies, it may be necessary to provide a plurality of such maps for different supply voltages or supply voltage range. 4 shows several maps for different supply voltages (between 36V and 56V), by means of which the determining means 1 1 C based on the actuator current ("current, A") and the duty cycle of the drive signal H1 ("DutyCyle,%") the actuator position (" With a supply voltage of between 36V and 56V, exactly one actuator position can be uniquely assigned to each value pair of current and duty cycle The uppermost characteristic field in FIG. 2 forms that for the supply voltage in the range of 36V and the lowest characteristic field in Fig. 2, that for the supply voltage is in the range of 56V.

Corresponding maps may alternatively or additionally be provided for the actuator temperature, which results in particular from the duty cycle and the supply voltage. Such a map represents the clear relationship between the actuator temperature and the duty cycle.

In the system according to FIG. 2, optional filters 15 may be provided in addition to the explicitly described or named components. The elements 16 each represent an optional signal conditioning for the two-position controller 12.

reference numeral

1 electromagnetic actuator

Coupling device Magnetic coil

anchor

Eddy-current ring

casing

Coupling device, coupling sleeve component, shaft

Component, shaft

10 storage products

1 1 microcontroller

1 1A. 1 1 B module

1 1 C investigative agent

12 Analog two-point controller

12A comparator circuit

12B RS flip-flop

13 bridge drivers

14 bridge circuit

15 filters

16 signal conditioning

H1, H2 drive signal

L rotation axis

Claims

claims

1 . 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 of a linear actuator, characterized by a two-point controller (12) for operating the actuator (1) and a determination means (1 1 C) ), which is designed to determine a time profile of the control signal (H1) output by the two-point controller (12) and to determine therefrom the operating state.

2. Apparatus according to claim 1, wherein the two-position controller (12) is an analog two-point controller.

3. Apparatus according to claim 2, wherein the two-position controller (12) is constructed discretely in hardware.

4. Device according to one of the preceding claims, wherein the two-position controller (12) an upper current limit and a lower current limit are predetermined, by which he limits the the actuator (1) supplied electric current.

5. Device according to one of the preceding claims, wherein the determining means (1 1 C) is adapted to determine one of the duty cycle and duty cycle of the drive signal (H1) and to determine from the one of the duty cycle and duty cycle an actuator temperature.

6. Device according to one of the preceding claims, wherein the determining means (1 1 C) is adapted to determine one of frequency and period of the drive signal (H1) and to determine the actuator (1) supplied electric current and from one of the frequency and period duration and from the current to determine an actuator position (1).

7. Device according to one of the preceding claims, wherein the determining means (1 1 C) is adapted to include a supply voltage of the actuator (1) in the determination of the operating state.

8. Vornchtung according to one of the preceding claims, wherein the determining means (1 1 C) has a lookup table or a map or other mathematical function and is adapted to the operating state of the actuator (1) hereby and with the drive signal (H1) to investigate.

9. 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 for determining a Operating state of the actuator (1) according to one of the preceding claims.

10. Motor vehicle drive train, characterized by a coupling device (2) according to claim 9.