GB2597809A

GB2597809A - Method for operating a cooling fan module of a motor vehicle

Info

Publication number: GB2597809A
Application number: GB2015024.9A
Authority: GB
Inventors: Bhagwat Hemant
Original assignee: Brose Fahrzeugteile SE and Co KG
Current assignee: Brose Fahrzeugteile SE and Co KG
Priority date: 2020-07-29
Filing date: 2020-09-23
Publication date: 2022-02-09
Also published as: GB202015024D0

Abstract

A cooling fan module 2 of a vehicle has a fan motor 12 and fan wheel 14 and communicates with further components 4 (e.g. engine control unit, ECU) of the vehicle, ideally via a pulse width modulation (PWM) interface 6. When a communication fault occurs a first temperature ‘TC’ of the cooling fan module is determined, e.g. by a temperature sensor on a controller 8 of the module. A second temperature ‘TM’ of an engine compartment is estimated based upon the first temperature, ideally using a predetermined offset temperature (e.g. 15 degrees Celsius). The rotational speed of the fan motor is controlled using the second temperature via open loop or closed loop control. The control may compare the second temperature with a stored characteristic curve or table stored in non-volatile data memory and base control of the fan speed on the curve/table. By controlling fan speed based upon a predicted engine compartment temperature the cooling fan module saves energy over prior systems that run a fan at full speed during communications failure.

Description

S

Description

Method for operating a cooling fan module of a motor vehicle The invention relates to a method for operating a cooling fan module of a motor vehicle, in particular in the event of a communication fault with other vehicle components. The invention furthermore relates to software on a data storage medium and to a cooling fan module for carrying out the method.

Electrically or electromotively driven or drivable motor vehicles, such as for example electric or hybrid vehicles, conventionally comprise an electric motor as the electrical drive system with which one or both vehicle axles are drivable. For the purposes of being supplied with electrical energy, the electric motor is typically coupled with an onboard (high-voltage) battery as an electrical energy storage device. A battery should here and hereinafter in particular be taken to mean a rechargeable, electrochemical secondary battery, for example a storage battery.

As electrical prime movers, such electric motors generate comparatively little waste heat during operation, as a result of which, in comparison with combustion engines, the cooling apparatus requires only a small cooling capacity. Electrically driven or drivable motor vehicles are, however, subject to the additional problem that the battery begins to degenerate at a high battery temperature, for example of higher than 45°C. This means that at such high temperatures electrochemical reactions occur within the battery which damage or completely destroy the battery.

In order to improve electromobility, there is frequently a desire for "quick charge modes" in which the onboard battery is charged within the shortest possible period of time. Comparatively high current intensities arise in the course of such quick charging which consequently bring about an increase in battery temperature during the charging process.

Battery charging generally proceeds when the vehicle is at a standstill, which means that no airstream is available for cooling. In order to improve cooling capacity in the battery (quick) charge mode, it is for example possible to generate a cooling stream of air through a heat exchanger through which a coolant flows by means of a cooling fan module (CFM).

The cooling fan module is typically arranged, in the direction of travel, behind a radiator core or cooling package of a radiator (heat exchanger) of the motor vehicle. With the assistance of a fan wheel of the fan, air is drawn through the radiator core and directed into the engine compartment in which the electromotive drive and the vehicle battery are arranged. Additionally or alternatively, the cooling fan module is for example integrated into a wheel arch cooling system of the motor vehicle with which a cooling air stream can be generated transversely of the direction of travel.

Once installed, the cooling fan module is connected for signalling and communication purposes to further vehicle components, in particular further control devices, such as for example an engine control unit (ECU) of the drive system. During operation, the cooling capacity of the cooling fan module is open-and/or closed-loop controlled on the basis of the temperature of the engine compartment, wherein the further vehicle components transmit the data required for this purpose to the cooling module. Cooling capacity is here open-and/or closed-loop controlled by modifying the (motor) rotational speed of the electromotive fan motor and thus by modifying the rotational speed of the fan wheel.

In normal mode, a controller, i.e. a control device, of the cooling fan module is provided via an interface for example with a rotational speed signal, in particular in the form of a pulse-width modulation (PWM), as a function of engine compartment temperature. This means that for example the engine control unit of the drive system generates the PWM signal as a function of an engine compartment temperature and of a coolant temperature and sends it via the interface to the cooling fan module. Via the interface, the cooling fan module controller identifies the pulse-duty factor with the assistance of software and, on that basis, determines the desired rotational speed value for actuation and/or closed-loop control of the fan motor. For example, the fan wheel is intended to rotate at a nominal speed of 1500 rpm (revolutions per minute) when the pulse-duty factor is between 15% and 85%.

In the event of a breakdown in communication between the cooling fan module controller and the further vehicle components, no data or signals from the other devices, on the basis of which the cooling capacity would be controllable/adjustable, are available to the cooling module controller. In the event of such a fault or breakdown, the fan motor is generally operated by the controller at a fixed, stored rotational speed. This means that the cooling fan module delivers a fixed cooling capacity which is independent of the engine compartment temperature and the coolant temperature and the battery temperature and thus of the required cooling capacity. In order to ensure sufficient cooling capacity, the rotational speed in such an emergency mode (emergency operating mode) is set comparatively high which means that emergency mode is comparatively energy-intensive.

The object of the present invention is to provide a particularly suitable method for operating a cooling fan module. In particular, the intention is to obtain a reliable and energy-saving emergency mode in the event of a breakdown in communication. It is furthermore an object of the invention to provide particularly suitable software and a particularly suitable cooling fan module for carrying out the method.

According to the invention, the object is achieved with regard to the method with the features of claim 1, with regard to the software with the features of claim 6 and with regard to the cooling fan module with the features of claim 7. Advantageous configurations and further developments are the subject matter of the subclaims.

To the extent that method steps are described below, advantageous configurations for the software and/or the cooling fan module are in particular obtained by the software/cooling fan module being configured to carry out one or more of these method steps. The advantages and configurations stated with regard to the method are also applicable mutatis mutandis to the software and/or the cooling fan module and vice versa.

The conjunction "and/or" should here and hereinafter be taken to mean that the features linked by means of this conjunction may be configured not only together but also as alternatives to one another.

The method according to the invention is provided, suitable and designed for operating a cooling fan module of a motor vehicle. The motor vehicle is for example an electrically driven or drivable motor vehicle, in particular a hybrid or electric vehicle. The cooling fan module has a fan motor and fan wheel driven thereby, wherein the cooling fan module is connected for signalling purposes to further components of the motor vehicle (vehicle components). "Further components of the motor vehicle" is here in particular taken to mean an engine control unit or ECU of an electromotive drive system of the motor vehicle. The engine control unit is for example coupled for signalling purposes via an interface, in particular via a PWM interface, with the cooling fan module or the electronics thereof.

In the event of a fault in which communication of the cooling fan module with the components breaks down, i.e. in the event of a breakdown in communication or a communication fault, a first internal temperature value of the cooling fan module is determined according to the method. In other words, a temperature value is determined which is acquired internally, i.e. within the cooling fan module. The first temperature value is thus a measure of the temperature of the cooling fan module or a measure of the temperature of a component of the cooling fan module.

On the basis of the first temperature value, a second temperature value is estimated or projected, wherein the second temperature value is a measure of the temperature of an engine compartment. The second temperature value may represent the temperature inside the engine compartment, or a temperature value dependent on it, such as a vehicle battery temperature or a coolant temperature.

"Engine compartment" should here in particular be taken to mean a compartment of the motor vehicle in which the further components, in particular the electromotive drive system and/or a vehicle battery, are arranged. According to the method, a rotational speed of the fan motor, thus the cooling capacity of the cooling fan module, is open-and/or closed-loop controlled on the basis of the estimated or projected second temperature value. A particularly suitable method for operating the cooling fan module obtained in this manner.

According to the invention, in the event of a breakdown in communication, the cooling fan module is thus switched from normal mode into an emergency mode in which the rotational speed of the fan motor or fan wheel, i.e. the provided cooling capacity, is varied on the basis of an estimated or projected (second) temperature value. In contrast with the prior art, the cooling fan module is thus not operated at a fixed rotational speed. It is consequently possible reliably to provide a required cooling capacity even in the event of a breakdown in communication, wherein it is additionally likewise possible to reduce the cooling capacity as necessary. A particularly energy-efficient or energy-saving emergency mode is thus obtained.

The second temperature value is estimated or projected on the basis of the first temperature value. "Estimation" or "estimate" should here and hereinafter be taken to mean an approximated determination of the engine compartment temperature or of the second temperature value by evaluating the first temperature value, for example by appearance, precharacterized measurements, stored tables or characteristic curves, or by means of statistical/mathematical methods.

"Projection" or "projected" should here and hereinafter in particular be taken to mean a predictive assessment, i.e. a prediction, in which, on the basis of the first temperature value, optionally with reference to mathematical or physical models, the second temperature value for the engine compartment which occurs with an adequate probability is calculated or predicted. What level of probability is deemed to be adequate here and how high the probability actually is, is initially unimportant. It may, for example, be established from past measurement data or from appropriate testing or trials. Different projected second temperature values are obtained for different motor vehicles, operating and ambient conditions or application scenarios.

The fault or a breakdown in communication is, for example, a PWM line failure or a bus communication fault, for example in a LIN (Local Interconnect Network) or CAN (Controller Area Network) bus.

In the case of a PWM line failure, thus for example a PWM interface fault, it is for example possible to establish by software means whether the line is short-circuited or open.

A LIN communication fault may, for example, be identified by means of a LIN bus timeout. If a line bus timeout is identified, the slave normally passes into an idle state. If a LIN slave is wakeable and is woken by an internal resource, it normally sends a wakeup frame to the master and awaits a response from the master. In the absence of the cooling fan module receiving a response, a communication problem or breakdown in communication is identified.

In the event of a CAN communication fault, an assigned CAN controller has a hardwire register, i.e. a hard-wired register, by means of which a bus off state can be acquired for example by a fault counter or by means of an overflow flag.

In one suitable embodiment, the temperature of a controller, i.e. of a control device, of the cooling fan module is acquired as the first internal temperature value. During operation, the controller acquires and monitors its operating temperature, which means that no additional temperature sensors or the like are necessary for determining the first temperature value. A structurally particularly simple method involving a reduced number of components is thus made possible.

In one suitable further development, the second temperature value is estimated on the basis of a precharacterized offset. In other words, the second temperature value is determined or calculated from the first temperature value and the offset. The engine compartment temperature is consequently estimated in a particularly simple and time-saving manner.

Since, in the preferred application, the cooling fan module is arranged close to or in the region of the engine compartment, there is a relationship between the first temperature value and the second temperature value, i.e. between a controller temperature of the cooling fan module and an engine compartment temperature. This relationship or dependency is precharacterized, i.e. established from past measurement data or from appropriate testing or trials. A measurement of the correlation between the engine compartment temperature and the cooling fan module temperature is, for example, carried out as the precharacterization. The controller temperature of the cooling fan module and the engine compartment temperature here in particular have a linear relationship, for example the temperatures, and thus the temperature values, differ by a constant temperature difference or temperature offset, for example by 15°C (degrees Celsius) or 15 K (kelvin). This temperature difference is stored as an offset, so enabling a particularly simple determination or estimation of the second temperature value on the basis of the first temperature value.

In one conceivable configuration, the second temperature value is compared with a stored characteristic curve or table, wherein the rotational speed of the fan motor is open-and/or closed-loop controlled on the basis of the result of the comparison, i.e. on the basis of the characteristic curve or table. In other words, a stored table or characteristic curve is provided which assigns a respective fan rotational speed to the estimated or projected second temperature value. Simple and reliable open-and/or closed-loop control of rotational speed in emergency mode is consequently obtained.

In one convenient configuration, the first and/or second characteristic curve or table(s) are stored in a nonvolatile data memory, in particular an NVRAM (Non-Volatile Random-Access Memory).

One additional or further aspect of the invention provides software on a medium or data storage medium for carrying out or executing the above-described method. This means that the software is stored on a data storage medium and is provided, suitable and designed for executing the above-described method. Particularly suitable software for operating a cooling fan module is consequently obtained, with which the functionality for carrying out the method according to the invention is implemented in software. The software is thus in particular operating software (firmware), wherein the data storage medium is for example a data memory of the controller.

The cooling fan module according to the invention is provided, suitable and configured for a motor vehicle. The motor vehicle is for example an electrically driven or drivable motor vehicle, in particular an electric or hybrid vehicle. The cooling fan module is for example arranged behind a radiator core or cooling package of a radiator (heat exchanger) of the motor vehicle or in a wheel arch cooling system. The cooling fan module has a fan motor and a fan wheel driven thereby. The fan wheel is for example arranged in a fan wheel opening of a fan shroud. The fan motor in particular takes the form of an electric motor. The fan motor is here coupled with a cooling fan module controller as control device or control unit. The controller is here generally configured with regard to software and/or circuitry for carrying out the above-described method according to the invention.

The controller is thus specifically configured to identify a fault or breakdown in communication and, in the event of a fault, to determine a first temperature value as a measure of an internal cooling fan module temperature. The controller is furthermore provided and configured to estimate, on the basis of the first temperature value, the second temperature value as a measure of the engine compartment temperature and to set and/or closed-loop control a rotational speed of the fan motor on the basis of the second temperature value.

In a preferred configuration, the controller is at least essentially formed by a microcontroller with a processor and a data memory in which the functionality for carrying out the method according to the invention in the form of operating software (firmware) is implemented in software, such that the method, optionally in interaction with an apparatus user, is automatically carried out on execution of the operating software in the microcontroller. For the purposes of the invention, the controller may however alternatively also be formed by a non-programmable electronic component, such as for example an application-specific integrated circuit (ASIC) in which the functionality for carrying out the method according to the invention is implemented with circuitry means.

An exemplary embodiment of the invention is explained in greater detail below with reference to drawings, in which: Fig. 1 shows a simplified, schematic representation of a cooling fan module and an engine control unit, and Fig. 2 shows a temperature diagram for an engine compartment temperature and a controller temperature.

Mutually corresponding parts and quantities are always provided with the same reference signs in the all figures.

Fig. 1 shows a highly simplified, schematic representation of a cooling fan module 2 of a motor vehicle and an engine control unit 4 coupled therewith as a further vehicle component. The cooling fan module 2 and the engine control unit (ECU) 4 are connected to one another for signalling purposes via a PWM interface 6.

The cooling fan module 2 has a controller 8 as control device which open-and/or closed-loop controls a supply unit 10 of a fan motor 12. The fan motor 12 for example takes the form of a DC motor with brushgear, with a brushless electric motor for example also alternatively being conceivable. The fan motor 12 is connected for drive to a fan wheel 14.

The engine control unit 4 is assigned to a drive motor of the motor vehicle, wherein the cooling fan module 2 is arranged in the region of an engine compartment of the drive motor. In normal mode, the engine control unit 4 generates a PWM signal as a function of the engine compartment temperature and sends this signal via the PWM interface 6 to the cooling fan module 2. Via the PWM interface 6, the controller 8 of the cooling fan module 2 acquires the pulse-duty factor with the assistance of software, and determines therefrom a rotational speed value for actuation and/or closed-loop control of the fan motor 12 or supply unit 10. For example, the fan wheel 14 is intended to rotate at a nominal speed of 1500 rpm when the pulse-duty factor is between 15% and 85%.

The schematic temperature diagram of Fig. 2 in each case plots horizontally, i.e. along the abscissa (x-axis), an engine compartment temperature TM of the engine compartment, and along the vertical ordinate (y axis) a controller temperature TC of the controller 8, for example in degrees Celsius (°C).

Fig. 2 shows a linear course 16 for the engine compartment temperature TM as a function of the controller temperature TC. As is comparatively clear from Fig. 2, the engine compartment temperature TM and the controller temperature TC have a substantially constant temperature difference or a constant (temperature) offset AT of for example approx. 15K.

In the event of a fault in the PWM interface 6 or a breakdown in communication, the controller 8 switches from a normal mode to an emergency mode. In emergency mode, no PWM signal indicating the rotation speed of the cooling fan module 2 from the engine control unit 4 is available to the controller 8. In emergency mode, the controller 8 determines or acquires a controller temperature TC as a first temperature value. The course 16 or its incline respectively is stored as a precharacterization in the controller 8, such that the controller 8 estimates a temperature value for the engine compartment temperature TM on the basis of the controller temperature TC and the known offset AT. The controller 8 furthermore has a stored table or characteristic curve which assigns a rotational speed value to the estimated engine compartment temperature TM. The table or characteristic curve is in particular stored in a nonvolatile memory of the controller 8. The controller 8 open-and/or closed-loop controls the fan motor 12 or the supply unit on the basis of this rotational speed value.

The invention is not limited to the above-described exemplary embodiments. Rather, other variants of the invention may also be deduced therefrom by a person skilled in the art without departing from the subject matter of the invention.

Furthermore, in particular all the individual features described in connection with the exemplary embodiments may also be combined together in different ways, without departing from the subject matter of the invention.

List of reference signs 2 Cooling fan module 4 Engine control unit 6 PWM interface 8 Controller Supply unit 12 Fan motor 14 Fan wheel 16 Course TM Engine compartment temperature value TC Controller temperature value AT Offset

Claims

Claims Method for operating a cooling fan module (2) of a motor vehicle, wherein the cooling fan module (2) has a fan motor (12) and a fan wheel (14) driven S thereby, and wherein the cooling fan module (2) is connected for signalling purposes to further components (4) of the motor vehicle, - wherein, in the event of a fault in which communication of the cooling fan module (2) with the components (4) breaks down, a first internal temperature value (TC) of the cooling fan module (2) is determined, -wherein, on the basis of the first temperature value (TO), a second temperature value (TM) for the temperature of an engine compartment is estimated, and - wherein a rotational speed of the fan motor (12) is open-and/or closed-loop controlled on the basis of the second temperature value (TM).
2. Method according to Claim 1, characterized in that the temperature of a controller (8) of the cooling fan module (2) is determined as the first temperature value (TO).
3. Method according to Claim 1 or 2, characterized in that the second temperature value (TM) is estimated on the basis of a precharacterized offset (AT).
4. Method according to one of Claims 1 to 3, characterized in that the second temperature value (TM) is compared with a stored characteristic curve or table, wherein the rotational speed is open-and/or closed-loop controlled on the basis of the characteristic curve or table.
5. Method according to Claim 4, characterized in that the characteristic curve or the table is stored in a nonvolatile data memory.
Software on a data storage medium for carrying out a method according to one of Claims 1 to 5.
7. Cooling fan module (2) of a motor vehicle, comprising a fan motor (12) and a fan wheel (14) driven thereby together with a controller (8) for carrying out a method according to one of Claims 1 to 6.