EP2274509B1 - Method and device for operating a drive device, in particular an engine cooling fan of a motor vehicle - Google Patents

Abstract

The invention relates to a method and a device for operating a drive device. According to the invention, it is provided that the lower speed limit (n₁) and the upper speed limit (n₂) of a critical speed range [n₁; n₂] of the drive device are determined when operating the drive device, that the target speed (n_soll) of the drive device is determined and that the operation of the drive device is done at one of the speed limits if the target speed is within the critical speed range. Through this procedure, it is for example avoided that the drive device is operated in a speed range in which the environment of the drive device or the device itself is excited into characteristic vibrations that are undesirable noise and/or vibrations.

Description

Technical area

The invention relates to a method and a device for operating a drive device.

State of the art

From practice, a method and an apparatus for operating a drive device in the form of an engine cooling fan for the internal combustion engine of a motor vehicle known The engine cooling fan is used to pressurize an engine radiator with an air flow and thus cool the heated by the engine and circulated between the engine and engine radiator coolant and Dissipate heat of the combustion process from the engine into the environment.

Usually, the drive of the engine cooling fan in modern vehicles by a DC motor. In order to reduce the energy consumption for this electric drive, its power is adapted to the currently dissipated by the engine combustion heat.

In the simplest case, this happens because the engine cooling fan is switched on only when the airflow generated by the driving situation for engine cooling is no longer sufficient, and then operated at a specified speed, which ensures sufficient engine cooling in all conceivable driving and environmental situations.

Energetically more favorable, however, is a control in which the power of the engine cooling fan during driving is continuously adapted to the actual required cooling capacity. The control unit of the engine cooling fan (Fan Control Module - FCM) used for this purpose is able to change the speed of the electric drive of the engine cooling fan over a wide speed range, for example from 0 to 3,000 min ^-1. The required speed n _soll required for the current driving operation is thereby defined in the vehicle control unit (ECU) by the engine management system of the internal combustion engine and transmitted as PWM (pulse wave modulation) signal to the engine cooling fan. The conversion of the speed requirement into an electrical voltage for the drive of the engine cooling fan then takes place in the control unit of the engine cooling fan.

The engine cooling fan is a source of noise and, as such, is taken into account in determining the noise requirements at the vehicle level. In critical speed ranges, the engine cooling fan may possibly produce an increased noise level due to resonance alone or in its environment. Also, the electric drive of the engine fan may cause vibrations corresponding to the natural frequency of the engine cooling fan or its environment.

From the US 2003/133242 A1 a control system for a cooling fan with a viscous coupling is known, wherein the speed of the cooling fan is limited when there is a risk of overheating of the viscous coupling.

The EP 1085 180 A2 discloses a viscous clutch control method wherein, when a control signal is provided to drive the drive motor where the viscous clutch can enter an overheating region, the control signal is modified to a value above or below the overheat range.

The JP 2004 044507 A further shows a controller for a cooling fan, which is operated alternately at a first speed, which is lower than a speed at which the vibration of a gas-powered engine by the Drive motor of the cooling fan is increased, and a second speed, which ensures sufficient air flow for heat dissipation.

From the G B 2 442 177 A finally a control device for the drive motor of a cooling fan is known, wherein the resonance frequencies of the cooling fan and the drive motor are determined based on the detected speed of the cooling fan and the detected speed of the drive motor. If it is determined that the resonance frequency of the cooling fan is in a resonance range of the drive motor, the speed of the cooling fan is increased to avoid resonance between the drive motor and the cooling fan.

The invention has for its object to further optimize the performance of the drive device in particular with regard to the development of noise and other vibrations.

Disclosure of the invention

The object is achieved in a drive device of the type mentioned above in that first a lower and upper limit speed of a critical speed range of the drive device and that subsequently a desired speed of the drive means are determined. The drive device is then operated at the lower or the upper limit speed, provided that the setpoint speed is in the critical speed range. According to the invention it is further provided that the drive means is operated at the lower limit speed, if the target speed is in the critical speed range and the specific target speed at a first time greater than or equal to the specific target speed at a subsequent time.

By this procedure is avoided, for example, that the drive device is operated over a long period of time in a speed range in which their environment or they themselves are stimulated to natural oscillations, which are undesirable as noise and / or vibration. If it is necessary to pass through the critical speed range to reach one of the limit speeds, this is done quickly, so that the case occurring impairments are as small as possible. Characterized in that the drive device is preferably operated at the lower limit speed, if the target speed is in the critical speed range and the specific target speed at a first time is greater than the predetermined Solldrehzah at the subsequent time, the power demand decreases over time, so that It is expected that the speed request will soon be below the lower limit speed anyway. The drive device is operated so far with the energetically favorable lower limit speed. If the determined setpoint speed corresponds to a subsequent point in time of the determined setpoint speed at the subsequent time point, it can further be ensured that the power demand neither increases nor decreases over time.

The determination of the critical speed range can in principle also take place during the operation of the drive device, for example by regularly driving through the entire speed range and determine the noise or vibrations occurring. In systems whose resonance behavior does not change or only insignificantly changes with time, however, the upper and / or lower limit rotational speeds are preferably determined in advance, for example by a laboratory test with a suitably equipped vehicle. The thus determined upper and / or lower limit speed can then be stored electronically in a simple manner.

The setpoint speed of the drive device is determined after a special training at intervals, in particular in periodic recurrence of, for example, 5 to 15 seconds. By comparing the target speed at a first time with the target speed at a subsequent time can be determined whether the demands on the performance of the drive device increase or decrease. This criterion can be used to determine whether to operate the drive device with the upper limit speed or the lower limit speed to avoid the critical speed.

Advantageously, it is further provided that the drive means is operated at the upper limit speed, if the target speed is in the critical speed range and the specific target speed at a first time is less than the specified target speed at the subsequent time. The increase in the required power is thus counteracted by the fact that the drive device is already operated at a positive gradient of the number of revolutions by the upper limit speed.

A suitable device for carrying out the method is characterized by a drive means, means for determining the desired speed of the drive means and means for comparing the target speed with a certain critical speed range. In a motor vehicle, these means can be generated in a simple manner by adaptation of the usual control devices of the vehicle, internal combustion engine and / or engine cooling fan.

The existing means can also be adapted to store a predetermined critical speed range, for example, by storing the critical speed range in the existing there electronic data storage.

Brief description of the drawings

• Fig. 1 die Darstellung eines erfindungsgemäß ausgestatteten Kraftfahrzeugs,
• Fig. 2 ein Diagramm mit der Darstellung der Datenübertragung vom Verbrennungsmotor zum Motorkühlgebläse,
• Fig. 3 eine graphische Darstellung des geforderten und des gemessenen Geräuschpegels über die Drehzahl des Motorkühlgebläses, und
• Fig. 4 ein Flussdiagramm zur Steuerung des Antriebs des Motorkühlgebläses.

The figures illustrate the example of an engine cooling fan of a motor vehicle schematically the implementation of the method according to the invention and the means used therein. It shows:

• Fig. 1 the representation of a motor vehicle according to the invention,
• Fig. 2 a diagram showing the data transmission from the internal combustion engine to the engine cooling fan,
• Fig. 3 a graphical representation of the required and the measured noise level on the speed of the engine cooling fan, and
• Fig. 4 a flowchart for controlling the drive of the engine cooling fan.

Description of embodiments

This in Fig. 1 Motor vehicle 1 has an internal combustion engine 2 and an engine radiator 3, which are connected to one another via coolant lines 4, 4 'and form a cooling circuit. An impeller pump, not shown, circulates the cooling liquid in the cooling circuit. In the area of the engine radiator 3, an engine cooling fan 5 with an electric drive 6 is arranged. This increases depending on its speed, the air flow through the engine radiator 3 and thus improves the heat dissipation from the engine radiator 3 in the environment.

The internal combustion engine 2 is equipped with an electronic controller 7 (ECU) which manages the data and processes required to operate the internal combustion engine 2 and other vehicle systems (eg, airbag system). This data also includes the temperature of the coolant and the resulting power demand on the engine cooling fan 5. The central controller 7 (ECU) in turn communicates with the controller 8 (FCM) of the engine cooling fan 5 via a bus system.

Fig. 2 shows the transmission and conversion of the data in detail.

The target speed n _soll determined by the controller 7 (ECU) of the internal combustion engine 2 is sent as a coded signal to the controller 8 (FCM) of the engine cooling fan 5. The controller 8 provides on the basis of this speed request, a voltage V, which _is required for operating the drive 6 of the engine cooling fan 5 with the required target speed n set.

How out Fig. 3 As can be seen, the noise emissions (in dB (A)) increase when operating the engine cooling fan 5 with increasing speed n (in min ^-1 ). Even if the overall noise level is substantially below the limit specified by the vehicle manufacturer, shown in dashed lines, critical speed ranges [n ₁ ; n ₂ ] exist, in which due to resonance an increase in the noise occurs. In the embodiment, the critical speed range [n ₁ ; n ₂ ] is defined by the lower limit speed n ₁ and the upper limit speed n ₂ and is determined experimentally.

This in Fig. 4 The corresponding flow is shown in the controller 7 of the internal combustion engine 2, in the controller 8 of the engine cooling fan 5 (as described below) or in another control module of the motor vehicle 1, which provides appropriate capacity.

The determined by the controller 7 of the engine 2 target speed n _is then checked by the controller 8 of the engine cooling fan 5, whether they are above the lower limit speed n ₁ , below the upper limit speed n ₂ and thus within the critical speed range [n ₁ ; n ₂ ] lies. If this is not the case (result: no), the speed request is forwarded unchanged. The drive 6 of the engine cooling fan 5 is thus supplied with the voltage V, which _is required to operate with the target speed n _soll .

On the other hand, the setpoint speed n _soll is between the lower limit speed n ₁ and the upper limit speed n ₂ and thus within the critical speed range [n ₁ ; n ₂ ] (result: yes), the next step determines whether the gradient of the speed request is positive (Δ n _soll = (n _soll (t _{k + 1} ) - n _soll (t _k ))> 0). In this case, the required target rotational speed n increases _to a determination of the time t _k for the temporally subsequent determination at time t _{k + 1} at. If this is the case (result: yes), the upper limit speed n _{2 is} determined as the corrected setpoint speed n _{soll korr} and the drive 6 of the engine cooling fan 5 is already supplied with a slightly too high voltage as a result of the increasing cooling power requirement.

If, on the other hand, the gradient of the speed request is equal to zero or negative (result: no), the lower limit speed n _{1 is} set as the corrected setpoint speed n _{soll corr} in anticipation of a constant or decreasing cooling power requirement. If the now set cooling performance proves to be too low, a positive gradient of the speed requirement will be set in the following determinations and the limit speed will be raised to the upper value n ₂ . A suitable algorithm prevents the corrected setpoint speed n _{soll corr} fluctuates in rapid succession between the limit speed n ₁ and n ₂ .

In a modification of this sequence of processes, it is also conceivable _to always provide the lower limit speed n ₁ as the corrected setpoint speed n _{soll cor} , provided that the required setpoint speed n _soll in the critical speed range [n ₁ ; n ₂ ], and to raise the cooling power only when the target speed n _soll exceeds the upper limit speed n ₂ . It is also conceivable to always work with an excess of cooling power, provided that the required setpoint speed n _soll in the critical speed range [n ₁ ; n ₂ ] is, in this case, as the corrected setpoint speed n _{soll corr} so set the upper limit speed n ₂ .

Claims (9)

1. Method for operating a drive device which serves as a drive (6) for an engine cooling fan (5), comprising the steps of:

   - determining a lower and an upper limit rotation speed (n₁, n₂) of a critical rotation speed range [n₁; n₂] of the drive device,

   - determining a setpoint rotation speed (n_set) of the drive device,

   - operating the drive device at the lower or the upper limit rotation speed (n₁, n₂) if the setpoint rotation speed (n_set) is in the critical rotation speed range [n₁; n₂],
   characterized by the further step of:

   - operating at the lower limit rotation speed (n₁) if the setpoint rotation speed (n_set) is in the critical rotation speed range [n₁; n₂] and the determined setpoint rotation speed (n_set) at a first time (t_k) is greater than or equal to the determined setpoint rotation speed (n_set) at a subsequent time (t_k+1).
2. Method according to Claim 1, characterized in that the engine cooling fan (5) serves to cool an internal combustion engine (2), in particular of a motor vehicle.
3. Method according to either of the preceding claims, characterized in that the lower and/or the upper limit rotation speed (n₁, n₂) are/is predefined.
4. Method according to Claim 3, characterized in that the lower and/or the upper limit rotation speed (n₁, n₂) are/is electronically stored.
5. Method according to one of the preceding claims, characterized in that the setpoint rotation speed (n_set) is determined in preferably periodically recurring time intervals (t_k, t_k+1).
6. Method according to Claim 1 or 5, characterized in that the drive device is operated at the upper limit rotation speed (n₂) if the setpoint rotation speed (n_set) is in the critical rotation speed range [n₁; n₂] and the determined setpoint rotation speed (n_set) at a first time (t_k) is lower than the determined setpoint rotation speed (n_set) at the subsequent time (t_k+1).
7. Apparatus for carrying out the method according to one of the preceding claims, characterized by a drive device, means for determining the setpoint rotation speed (n_set) of the drive device, means for comparing the setpoint rotation speed (n_set) with a determined critical rotation speed range [n₁; n₂], and also means which operate the drive device in accordance with the method according to Claim 1.
8. Apparatus according to Claim 7, characterized by means for storing a predefined critical rotation speed range [n₁; n₂].
9. Apparatus according to Claim 8, characterized in that the means for storing the critical rotation speed range [n₁; n₂] comprise an electronic data storage unit.

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