WO2012171701A1

WO2012171701A1 - Method for operating an electric fan motor

Info

Publication number: WO2012171701A1
Application number: PCT/EP2012/057660
Authority: WO
Inventors: Yannick Mougey; Stefan Krug
Original assignee: Robert Bosch Gmbh
Priority date: 2011-06-16
Filing date: 2012-04-26
Publication date: 2012-12-20
Also published as: US20140136077A1; DE102011077652A1; CN103717852A; CN103717852B; EP2721267A1

Abstract

A method for actuating an electric fan motor for an internal combustion engine of a motor vehicle, comprising the steps: - determining an operating duration during which the fan motor is operated below a rotational speed which is critical with regard to pasting; - wherein if the operating duration exceeds a duration which is critical with regard to pasting, the fan motor is operated for a defined time duration at a washing rotational speed which is higher than the rotational speed which is critical with regard to pasting.

Description

Method for operating an electric fan motor

The invention relates to a method for operating an electric fan motor for an internal combustion engine of a motor vehicle. Furthermore, the invention relates to a control device for carrying out such a method. Conventionally, engine cooling fan devices are used to perform cooling functions in an internal combustion engine of a motor vehicle. In this case, a DC fan motor of the engine cooling fan device generally has a commutator with lamellae, via which rotor coils of the fan motor are energized by means of contacting brushes. A speed of the fan motor is usually controlled by an electronic control unit (ECU, Engine

Control unit) of the motor vehicle specified to ensure that an engine temperature is within an acceptable and safety-critical range. For example, the engine cooling fan device may be used in such a way that by means of its air flow, a number of coolers arranged behind one another in the engine compartment of the motor vehicle are cooled.

In a permanent control of the fan motor with too low a current or at a permanently low speed of the fan motor can disadvantageously a so-called "paste" of the commutator of the fan motor occur, being in slots between the slats of the commutator brush particles, dirt, oil etc. This results in the formation of a greasy layer which is often conductive due to the carbon dust of the brushes and can thereby adversely effect a reduced resistance or a short circuit between the commutator bars Failure of the fan motor come.

EP 1 871 998 discloses a method for controlling a fan motor, wherein a control unit drives a fan motor at a certain point in time for a predetermined period of time independently of the desired cooling capacity with a cleaning manipulated variable which is increased in relation to a control manipulated variable. It is the object of the present invention to provide an improved method for operating an electric fan motor for an internal combustion engine of a motor vehicle, which can prevent as far as possible pasting of the fan motor.

The object is achieved with a method for operating an electric fan motor for an internal combustion engine of a motor vehicle, comprising:

- Determining an operating period during which the fan motor is operated below a critical speed with regard to pasting;

- In case that the operating time exceeds a critical with respect to fattening of the fan motor duration, the fan motor with a washing speed which is greater than the critical speed with respect to paste, a defined period of time is operated.

By means of the method according to the invention, it is advantageously possible to reproducibly implement an effective strategy for avoiding or eliminating pasting of the fan motor due to a consideration of paste critical threshold values with respect to speed and operating time of the fan motor. Due to the systematic consideration of these parameters, it is thus advantageously possible to systematically counteract pasteurization of the fan motor as early as possible, thereby advantageously prolonging the service life of the fan motor and reducing the susceptibility of the internal combustion engine of the motor vehicle. Advantageously, the commutator of the fan motor is cleaned compared to the known methods only if it is actually required due to a detected exceeding of threshold values. Preventive cleaning processes without real needs and associated wear effects and operational inconvenience are advantageously avoided in this way.

An advantageous development of the method according to the invention provides that the critical speed with respect to pasting of the fan motor is approximately 2000 rpm (revolutions / minute). In this way, a threshold of a speed of the fan motor is advantageously predetermined and monitored, in whose long-term underrun a fattening of the fan motor is highly probable.

A preferred embodiment of the method specifies that a relative lapse of critical service life of the fan motor is approximately one hundred hours. As a result, an operating time of the fan motor is set below the critical speed in a defined manner, when exceeded, the fan motor is highly liable to breakage. An advantageous development of the method provides that the defined duration of the operation of the fan motor at a speed which is greater than the critical speed with respect to paste, is approximately ten minutes. This defines a so-called washing or cleaning time for the fan motor during which the fan motor must be washed to substantially eliminate unwanted paste substances.

A preferred embodiment of the method provides that the washing speed substantially corresponds to a maximum speed of the fan motor. Thereby, a speed is specified in a reproducible manner, in which the fan motor said washing time should be operated long to substantially eliminate unwanted pasty materials between the commutator of the fan motor.

An advantageous development of the method provides that the method is designed as a software of a control device of the motor vehicle. As a result, no hardware-related modification of the fan system for the internal combustion engine of the motor vehicle is required for carrying out the method according to the invention in an advantageous manner. Thus, the inventive method can be implemented in a simple manner in an already existing control unit of the motor vehicle without much extra effort.

An advantageous development of the method provides that the software is designed as part of a control software, wherein the software is processed cyclically. By thus carrying out the method according to the invention at regular intervals is advantageously carried out a regular and systematic testing of the fan motor to paste. so Liquorization can be systematically prevented as far as possible during the development process.

An advantageous development of the method according to the invention provides that the software has a high priority within the control software. This assists that the inventive method is preferably carried out, whereby a freedom from interference of the fan motor is supported and the fan motor in this way its intended cooling functionality can run as long as possible trouble-free.

An advantageous development of the method according to the invention provides that the critical values with regard to pasteurization for the rotational speed and the operating time of the fan motor are determined from experimental and / or simulation-technical investigations of the fan motor. Advantageously, in this way, for each individual fan motor, the most suitable numerical values for the rotational speed and operating time critical with respect to pasteurization can be used. An adaptability of the method to different types of fan motors is thereby advantageously supported.

An advantageous development of the method provides that the value for the washing speed is determined from experimental investigations of the fan motor. As a result, the respectively most suitable washing speed can be determined in a simple manner for each type of fan motor with high accuracy, at which the desired cleaning effect is optimally achieved in the execution of the method according to the invention.

The invention is explained below with reference to three figures in detail. The figures above all serve to explain the essential principles of the method according to the invention and are not intended to allow any concrete parameters to be taken from them. In the figures shows:

Figure 1 is a schematic representation of a cooling fan device for an internal combustion engine of a motor vehicle, for which the inventive method can be used; Figure 2 shows part of an embodiment of the method according to the invention, wherein critical threshold values are defined, monitored and evaluated; and FIG. 3 shows a further part of an embodiment of the method according to the invention, wherein in particular the washing or cleaning process is shown.

FIG. 1 shows in a highly simplified manner a cooling fan device 100, which is usually installed in an engine compartment of the motor vehicle (not shown) and used for cooling a coolant of an internal combustion engine (not shown) of the motor vehicle. For this purpose, the cooling fan device 100 generates a flow of air that passes through a radiator (not shown) and thereby cools the coolant in the radiator.

The cooling fan device 100 is controlled by a control unit 10, which may be designed, for example, as an electronic control unit (ECU, Electronic Control Unit). The controller 10 is electrically connected to a fan controller 20 (Fan Control Module, FCM) which is used to drive a fan motor 20 connected to the electric fan motor 30 of the cooling fan device 100. For this purpose, the control unit 10 transmits to the fan control unit 20 a pulse-width-modulated electrical signal, which converts the fan control unit 20 into a corresponding electrical voltage, in order thereby to control the fan motor 30 in terms of speed. In this way, the controller 10 the fan motor 30 before a desired speed and controls it accordingly.

The paste effect described above can undesirably arise because the fan motor 30 is operated for a long period of time below a so-called "crunch threshold." It has been found experimentally that fan motors 30, which rotate relatively slowly over a long period of time, are particularly susceptible to breakage ,

According to the invention, a method is proposed for detecting the danger of sticking and for avoiding or eliminating pastage. The method defines in numerically reproducible form the above-mentioned pastes The inventive method may preferably be implemented as a software program in the control unit 10, the control unit 10 as a central control unit (for example, as an engine control unit) of the motor vehicle or as a partial control device for controlling individual functions may be formed within the motor vehicle. Advantageously, any controller which sends speed requests to the fan control unit 20 can

Execution of the method according to the invention can be used. This advantageously results in great flexibility in the implementation of the method according to the invention.

Figure 2 shows a part of an embodiment of the method according to the invention with a schematic flow chart for the determination and evaluation of Verpastungsschwellen. In a step S1, it is checked whether a rotational speed of the fan motor 30 is below a rotational speed of the fan motor 30 that is critical with respect to paste. Typically, a threshold for this critical speed is about two thousand revolutions / minute (2000 rpm). In the event that said threshold speed is exceeded (branch N of step S1), a time counter which detects a time duration of operation of the fan motor 30 below the threshold speed is not operated in a step S2.

Otherwise (branch J of step S1), the time counter for detecting the operating time of the fan motor 30 is incremented below the threshold speed in a step S3. In a subsequent step S4, a check is made as to whether the time detected by the time counter has already reached a critical threshold with regard to pasting of the fan motor 30. A typical value for this threshold is about one hundred hours. If the critical operating time has not yet been reached (branch N of step S4), the process continues without further action. In the other case, therefore, if the operating time of the fan motor 30 running below the threshold speed has a critical value with regard to pasting is sufficient or exceeded, a bit switch is set to "true" in a step S5, whereby the method is informed that now there is an acute risk of fouling for the fan motor 30 or has already used the paste that is to say, in principle, a testing of conditions under which there is a risk of entanglement for the fan motor 30. The sequence of steps S1 to S5 of the method illustrated in Figure 2 is executed cyclically within the control unit 10, which supports the fan motor 30 systematically and regularly As a result, the pasting of the fan motor 30 is advantageously prevented at the beginning.

In a subsequent washing or cleaning process shown in principle in FIG. 3, the paste is counteracted by operating the fan motor 30 at a very high rotational speed.

FIG. 3 shows a further part of an embodiment of the method according to the invention with a sequence of steps S6 to S12, which is carried out in time subsequent to the steps S1 to S5 (see FIG. 2). In a step S6 it is checked whether the bit switch, which tells the procedure the risk of stickiness of the fan motor 30, is set to "true." In case the bit switch is not set to "true" (branch N of step S6) the procedure continues without further action. Otherwise (branch J of step S6), a time counter for detecting a washing time of the fan motor 30 is incremented in a subsequent step S7. In a subsequent step S8, it is checked whether the washing time has already reached a predefined length, at which a cleaning of the commutator of the fan motor 30 is to be expected. Typically, the required washing time for the fan motor 130 is about ten minutes, and the length of the washing time may depend on a washing speed of the fan motor 30. At a higher washing speed, the washing time is shortened accordingly, wherein a minimum value of the washing time is reached at the maximum speed of the fan motor 30. Thus, the value ten minutes of washing time is to be regarded as a typical value, which varies depending on the washing speed of the fan motor 30, wherein the embodiment of the method shown in Figure 3 starting from a maximum washing speed of the fan motor 30. In the event that the washing time has not yet elapsed (branch J of step S8), the washing speed of the fan motor 30 is set in a step S9 by means of the manner explained with reference to FIG 1 to a value which is above the Verpastungsschwelle. Particularly advantageously, this speed substantially corresponds to a maximum speed of the fan motor 30, whereby a washing time can be minimized. Typically, the washing time for the fan motor 30 in this case is about ten minutes.

In the event that the washing time for the fan motor 30 has already expired (branch N of step S8), this means that the copper commutator bars of the fan motor 30 substantially completely of pasty substances due to the centrifugal forces generated by rotating the fan motor 30 at high washing speed have been cleaned. In a subsequent step S10, the time counter for the detection of the washing time is reset to zero. In a subsequent step S1 1, the bit switch, which informs the method of the risk of sticking and initiates the washing of the fan motor 30, is reset to "false." In a subsequent step S12, the time counter for detecting the operating time of the fan motor 30 is also below the time of paste After completion of the execution of the steps shown in Figure 3 so the time counter for detecting the critical operating time of the fan motor 30 must be operated again about hundred hours to initiate a next cleaning or washing procedure for the fan motor 30.

Processing of steps S6 to S12 (see FIG. 3), as well as processing of steps S1 to S5 (see FIG. 2), are carried out cyclically, as a result of which a systematic cleaning of the fan motor 30 is carried out in an uninterrupted manner if necessary.

Particularly advantageously, the inventive method with the steps shown in Figure 2 and Figure 3 is performed with a high priority within a control software, which supports that the paste is already reduced or prevented in the approach. All of the steps of FIG. 2 are performed prior to the steps of FIG. 3, since the steps S1 to S5 of FIG. 2 are required in order to prevent the danger of during an operation of the fan motor 30 Define pasty defined to determine which is subsequently eliminated by means of steps S6 to S12 substantially.

The controller 10 may be any electronic controller that sends an instruction to the fan controller 20 to rotate the fan motor 30 at a defined speed. The method according to the invention is preferably implemented in software of the control unit 10.

It goes without saying that the stated numerical values of the parameters and thresholds are only to be understood as typical values for an exemplary embodiment of the method. Depending on the type and operating conditions of the fan motor 30, the stated numerical values can be changed, wherein the respectively most suitable values can be determined, for example, by means of experimental and / or simulation-technical methods. Due to the configuration of the method according to the invention as software of a control unit 10, the changed values can be used in a simple manner for carrying out the method. Advantageously, the inventive method for a variety of different fan motors 30 is easily adaptable.

In summary, a method for operating an electric fan motor for an internal combustion engine of a motor vehicle is proposed, which systematically provides a reproducible determination and reduction of undesired fattening of the electric fan motor due to the monitoring of predefined macerating thresholds.

A person skilled in the art will expertly modify and combine the features of the invention explained above and with reference to the figures.

Claims

claims

1 . A method of operating an electric fan motor (30) for an internal combustion engine of a motor vehicle, comprising:

Determining an operating period during which the fan motor (30) is operated below a critical speed with respect to paste;

wherein, in the case that the operating time exceeds a critical with respect to pasting of the fan motor (30) duration, the fan motor (30) with a washing speed which is greater than the critical speed with respect to paste, a defined period of time is operated.

2. The method of claim 1, wherein the respect to Verpastung the fan motor (30) critical speed is about 2000 U / min.

3. The method of claim 1 or 2, wherein the critical with respect to paste operating time of the fan motor (30) is approximately 100 hours.

4. The method according to any one of claims 1 to 3, wherein the defined period of time is about 10 minutes.

5. The method according to any one of claims 1 to 4, wherein the washing speed substantially corresponds to a maximum speed of the fan motor (30).

6. The method according to any one of claims 1 to 5, wherein the method is designed as a software of a control unit (10) of the motor vehicle.

7. The method of claim 6, wherein the software is formed as part of a control software, wherein the software is processed cyclically.

8. The method of claim 6 or 7, wherein the software within the control software has a high priority.

9. The method according to claim 1, wherein the numerical values for the rotational speed and the operating time of the fan motor that are critical with respect to pasting are determined from experimental and / or simulation-technical investigations of the fan motor.

10. The method of claim 9, wherein the value for the washing speed from experimental investigations of the fan motor (30) is determined.

1 1. Control device for carrying out the method according to one of Claims 1 to 10.

12. Control device according to claim 1 1, wherein the control device (10) is designed as a central control unit or as a partial control device of a motor vehicle.