EP1228294A1

EP1228294A1 - Method for controlling the cooling water temperature of a vehicle with an internal combustion engine

Info

Publication number: EP1228294A1
Application number: EP00978956A
Authority: EP
Inventors: Michael Baeuerle; Klaus Ries-Mueller
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1999-10-26
Filing date: 2000-09-27
Publication date: 2002-08-07
Also published as: WO2001031177A1; JP2003513191A; DE19951362A1

Abstract

A method for controlling the cooling water temperature of a vehicle with an internal combustion engine is disclosed, whereby at least one further sensor, for example, a knock sensor, or a vehicle control unit is used for determining the cooling water temperature. A control unit (2) determines a set value (tset) from the input values, by means of a control loop (29, 31, 32), taking account of the knocking behaviour. The regulated set temperature is used by a motor control unit to set the advance angle to early , for example.

Description

Method for regulating the cooling water temperature of a motor vehicle with an internal combustion engine

State of the art

The invention relates to a method for regulating the cooling water temperature of a motor vehicle with an internal combustion engine according to the preamble of the main claim.

It is already known to regulate the cooling water temperature of an internal combustion engine by keeping the engine temperature constant, for example by means of a thermostat, via a cooling water circuit with a heat exchanger. To dissipate the engine heat generated, the cooling water circuit to the heat exchanger (radiator) is opened as required via a valve and, if necessary, the cooling capacity of the radiator is supported by a fan. For modern internal combustion engines, for example in the case of direct injection for gasoline or for diesel, known measures such as temperature control, control of injection or ignition are no longer sufficient to optimize consumption and reduce pollutants in the exhaust gas.

Advantages of the invention The method according to the invention with the characterizing features of the main claim has the advantage over the fact that the cooling water temperature is controlled as a function of signals from at least one further sensor and / or at least one further 'vehicle control unit. As a result, the individual operating states of the internal combustion engine can be optimized in each individual phase, so that not only is there a reduction in fuel consumption, but pollutants are also reduced in the exhaust gas.

The measures listed in the dependent claims allow advantageous developments and improvements of the method specified in the main claim.

It is particularly advantageous that a knock sensor is provided as a further sensor, which detects the tendency of the internal combustion engine to knock and emits these signals to the control unit for the cooling water temperature. Since the knock tendency inter alia also depends on the temperature of the cooling water or the cylinder head temperature, the tendency of the engine to knock can also be reduced, for example, by reducing the cooling water temperature.

It is considered to be particularly advantageous that the control device determines the cooling water temperature as a function of the

Selects operating modes that are determined by the ratio of fuel to air in gasoline direct injection. The different operating modes enable different temperature levels, which the control unit can take into account advantageously when forming the setpoint. For example, double injection leads to a reduced tendency to knock. Depending on the design of the cooling system, this may increase the temperature setpoint for the cooling water during the double injection become. Accordingly, a higher temperature level is conceivable in shift operation, which may improve the flammability. In particular, the operating mode can also be influenced depending on the cooling capacity currently available or depending on the current temperature level. For example, it is foreseeable to drive at a higher engine temperature in a larger engine operating range in the most economical shift operation.

Favorable conditions also arise if the cylinder head temperature is increased during lean operation, since the fuel-air mixture can then be further emaciated.

In the case of an engine with variable valve train, it is advantageous if the target temperature for a decommissioned cylinder is reduced, since this cylinder then no longer generates combustion heat.

It is considered to be particularly advantageous that the target temperature for the cooling water is determined as a function of the efficiency of the ignition angle. A further parameter can thus be used to optimize the fuel consumption or the exhaust gas.

An assessment of the driver type takes place in modern transmission or engine management control units. Depending on the dynamics of the accelerator pedal movement and / or the brake application, the driver is classified as being more sporty or more economical. The evaluation is used, among other things, for the shift program for multi-stage automatic transmissions.

It is now advantageous to use this evaluation for the control and regulation of the target temperature. For example, a sporty driver type may have a lower target temperature due to the higher dynamics. Accordingly, the time constant of the temperature controller can be changed in the direction of faster temperature control.

Today's torque-based engine control systems continuously calculate the loss torque of the engine in normal operation. Changes in the torque loss, for example when idling, are adapted or learned and taken into account when calculating the manipulated variables of an engine control system (including: injection, air mass and ignition angle). A change in the friction losses of the motor is thus recognized in this loss torque adaptation. Here, too, it is advantageous to take these loss moments into account when determining the target temperature.

The target temperature should be set so that the torque loss is minimal. The same applies to the determination of the target temperature depending on the

Exhaust gas recirculation rate, boost pressure or from external devices such as a distance controller.

It is also advantageous that the information from a navigation system is used to set the target temperature. Using such navigation systems, the vehicle location, the vehicle destination and / or the planned or driven route can be determined. In such systems, among other things, accurate height information (height above sea level) is also available. For example, it is conceivable to lower the setpoint temperature to a minimum value on longer pass journeys, for example downhill, with longer phases in push mode. This then increases the friction losses of the engine, which leads to a higher braking effect, which is desired in this case. Continue to be thereby reducing blue smoke emissions. Before the end of the pass is reached, the setpoint temperature can then be raised again in order to achieve more favorable conditions with lower friction losses when the increased power output of the engine is to be expected.

Since no new hardware components are required for the implementation of this method, the implementation in the form of a control program appears to be particularly favorable, this control program being part of an engine control unit which is already present for controlling the engine.

drawing

An embodiment of the invention is shown in the drawing and explained in more detail in the following description.

Figure 1 shows a block diagram in a schematic representation and Figure 2 shows a flow chart.

Description of the embodiment

Figure 1 shows a block diagram of various engine components which are arranged according to the inventive method. An internal combustion engine 1 is first connected to a heat exchanger (cooler 6) via a cooling circuit with cooling water 5. A corresponding return line 5a leads from the cooler 6 back to the internal combustion engine 1. In this cooling circuit, a valve 9 is shown schematically, with which the inflow to the cooler 6 can be controlled. Furthermore, the cooler 6 is assigned a fan motor 7, which can increase the cooling capacity of the cooler 6. Both the fan motor 7 and also the valve or valves 9 are controlled via corresponding lines by a control unit 2 so that a predetermined target temperature for the cooling water 5 is reached. A temperature sensor 3 and a further sensor, for example a knock sensor 4, are connected to the inputs of the control device 2. The two sensors are located at suitable points in the cooling circuit on the internal combustion engine 1. An engine control unit or a vehicle control unit 8 is also connected to the internal combustion engine 1, which controls the fuel injection, the ignition and / or the valves or controls vehicle functions, for example. An output of the control unit 2 is connected to an input of the engine control unit 8 via a line 10. The method can be used for both gasoline and diesel engines.

In FIG. 1, only the components essential to the invention were shown in order to keep the overview. In practical implementation, however, significantly more electrical lines and hoses are required for the cooling water 5, but their representation has been omitted here.

The mode of operation of this arrangement is explained in more detail below with reference to FIG. 2.

The control diagram in FIG. 2 is based on an internal combustion engine 1 with direct gasoline injection (BDE). First of all, the control unit 2 specifies a temperature setpoint t _so _τ_ for the cooling water temperature, which is formed from a preferably stored map of the current engine load and the engine speed (position 21). In another map more parameters are stored, for example, an adaptation value Krada ^ ^{ur e>} - ^ne cylinder-specific pilot control of the Knock control. This value is a measure of the average knock tendency in a single operating area (item 22). After a conversion and normalization in position 23, a subtraction from the target value tset is carried out in position 26. ^In position 27, a signal (position 24) of knock sensor 4 is subtracted from the value in position 27 after corresponding conversion in position 25. This signal indicates whether knocking has occurred during the instantaneous loading of the internal combustion engine 1 or not. In position 28 the signal t _so obtained is called _] _ _] __Kr and specifies the new setpoint for the temperature of the cooling water 5, which takes into account the signal from the knock sensor 4. This setpoint is fed to position 30 of the control loop, which results from positions 29, 30 and 32. In this

Control loop, the delivery rate of a water pump is now operated, for example, with a proportional controller (P controller, position 29) and the actuators, pump, fan 7 or valves 9 (position 31). These measures result in a specific cooling capacity of the circulatory system with the cooling water 5, which is supplied to or removed from the internal combustion engine 1 (position 32). In terms of energy, this results in a temperature t- _j _ _st , which is compared with the upcoming temperature value ^t soll ^Kr ^ ⁿ position 30 and corrected. The result is available in position 33 and can be displayed, for example, on a display that is not shown. This control diagram is preferably executed as a control program and is part of the engine control unit 8. The engine control unit 8 is designed, for example, for engines with gasoline injection for the injection of the fuel, for the control of the ignition and / or the control of the valves. For the control of the engine functions, the engine control unit 8 can of course use the same map and the ones stored there Process data. This map is preferably designed with a RAM memory, in which data can both be written in and read out. The engine control unit 8, for example, also specifies the operating modes for the fuel-air mixture homogeneously, homogeneously lean or stratified depending on the operating load. The engine control unit 8 also controls the ignition angle for the gasoline engine and also takes the associated data from the stored map. Since the control unit 2 and the engine control unit 8 are coupled to one another via the line 10, the control unit 2 can pass the actual temperature tist ^{to the} engine control unit 8, so that this engine control unit 8 can also take the ignition angle into account, for example, taking into account the actual temperature t-j_ _s t- of the internal combustion engine 1 determined. The engine control unit 8 can, for example, pre-control depending on the cooling capacity in the case of temperature-critical operating parameters and thus specify an early ignition angle.

If it is provided in an alternative embodiment of the invention to individually cool the individual cylinders, the sequence shown in FIG. 2 can be carried out individually for each cylinder. The adaptation _values KR _acja or the _{knock signals are available individually for each} cylinder in modern engine management systems and can therefore be used directly for cylinder-specific temperature control. If, on the other hand, there is no cylinder-specific cooling water supply, then the adaptive knock value KR _acja is expediently _calculated from the mean value of the cylinder- _specific adaptation values for each cylinder. If knocking occurs, the temperature setpoint can then be reduced. This optimization method advantageously takes into account the cooling capacity, the operating operating point, the knock tendency and / or the ignition angle Optimal operation for low fuel consumption and low exhaust emissions achieved.

Claims

Expectations

1. Procedure for regulating the cooling water temperature of a

Motor vehicle with an internal combustion engine (1), a temperature sensor (3) detects the cooling water temperature and a control device (2) for the cooling water temperature actuates at least one valve (9) and / or at least one fan (7) in order to set a predetermined temperature setpoint ( T _so _ ^) des

To obtain cooling water (5), characterized in that at least one further sensor (4) or a further vehicle control device is provided, that its signals are fed to the control device (2), and that the control device (2) derives at least one setpoint from the supplied signals determined for the temperature of the cooling water (5), the setpoint being formed with a view to minimal fuel consumption and / or for optimizing the exhaust gas emissions.

2. The method according to claim 1, characterized in that the further sensor (4) is a knock sensor.

3. The method according to claim 1 or 2, characterized in that the control device (2) the cooling water temperature depending on the operating modes in the

Direct fuel injection (diesel or petrol) selects.

4. The method according to claim 3, characterized in that the control device (2) the target temperature for the cooling water (5) for the operating modes homogeneous or homogeneously lean fuel-air mixture or stratified fuel-air mixture.

5. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) depending on the type of injection, and / or the lambda value of the fuel-air mixture, in particular in the case of a double injection or a stratified injection.

6. The method according to any one of the preceding claims, characterized in that the control unit (2) increases the target temperature for the cylinder head during lean operation and delivers a signal to the engine control unit (8) for further emaciation of the fuel-air mixture.

7. The method according to any one of the preceding claims, characterized in that the control device (2) lowers the target temperature for a decommissioned cylinder.

8. The method according to any one of the preceding claims, characterized in that the control device (2) specifies the target temperature for the cooling water (5) depending on the tendency to knock.

9. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of the ignition angle or its efficiency.

10. The method according to any one of the preceding claims, characterized in that the control device (2) the target temperature for the cooling water (5) depending on the driver type, For example, specifies a sporty or economical driver.

11. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of the friction losses of the engine.

12. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of the exhaust gas recirculation rate of an exhaust gas recirculation system.

13. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of the signal of a boost pressure sensor in an engine with turbocharging, the target temperature being lowered when the boost pressure increases.

14. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of signals from a distance controller.

15. The method according to any one of the preceding claims, characterized in that the control device (2) determines the target temperature for the cooling water (5) as a function of signals from a navigation system.

16. The method according to any one of the preceding claims, characterized in that the control device (2) is designed as a control program and is preferably part of the engine control unit (8).