EP1308610A2 - Method and device for controlling a cooling system of an internal combustion engine - Google Patents

Abstract

The power of a coolant pump is regulated as a function of fuel quantity supplied to the engine. <??>An Independent claim is included for the corresponding control unit.

Description

The invention relates to a method and a device for controlling a Cooling system of an internal combustion engine hereinafter also called an engine.

Such a cooling system comprises a coolant pump which coolants through a Internal combustion engine conducts to cool them.

From the prior art it is known that a coolant pump for example connected a V-belt to the crankshaft of an internal combustion engine can be so that it is driven when the engine is running.

With regard to the state of the art, DE 195 08 104 C2 also describes Method known for regulating a cooling circuit of an internal combustion engine in the between a warm-up phase, an operating phase and a run-on is distinguished. The warm-up and operating phase is with the engine started determined by the coolant temperature at the engine outlet, which with a Coolant temperature limit for the warm-up phase is compared. In the The value is undershot on warm-up phase and when reaching or Detected exceeding the value on operating phase. In the warm-up phase, the Engine is not initially cooled until it reaches an initial coolant temperature Has. After reaching this initial temperature, however, one of the blowers generated air flow that is passed through a cooler module and that of the Coolant pump generated coolant flow depending on one Differential temperature setpoint of the coolant between the engine inlet and outlet is regulated. A differential temperature actual value necessary for the control is over the Heat flow from the internal combustion engine into the coolant is determined. The heat flow is in turn derived from the current coolant flow, the current engine load and the engine speed. The speed of the coolant pump changes with it the change in heat flow, so that short-term engine load and Changes in speed do not affect the operation of the coolant pump. Once the Temperature limit for the warm-up phase is reached, the so-called Operating phase. It controls the coolant pump and the fan in Dependence on the differential temperature setpoint and a temperature setpoint of the coolant at the engine outlet. The temperature setpoint is over a corresponding Map for a given engine temperature determined. In the follow-up phase in the the engine is turned off, the engine continues to cool when the coolant temperature exceeds a predetermined temperature limit. This procedure has the Disadvantage that the temperature or the difference of different as a control variable Temperatures in the cooling system can be used. Such temperatures in the cooling circuit are sluggish and ultimately only effects of the engine or vehicle operating point.

EP 0 952 315 A1 discloses a control system for minimizing consumption electrical energy in a cooling system of an internal combustion engine disclosed. Based on the engine temperature and vehicle speed detected by sensors and ambient temperature, one control unit controls one fan and one electric pump for cooling the internal combustion engine. By means of the sensors An operating point is determined on the basis of a characteristic map by a dissipate certain amount of thermal energy from the engine, which is an optimal Ratio of the sum of the energy supplied to the fan and the pump indicates. The control system has the disadvantage that several sensors are necessary to record certain parameters on which the engine is cooled depending. In addition to the costs associated with each individual sensor, there is also a Default risk of the same. It also applies that the measuring accuracy at temperature measuring points can be reduced by external influences and thus a regulation based on the Temperature is limited.

The object of the invention is a method and an apparatus for controlling a Provide cooling system of an internal combustion engine, being a reliable Cooling is made possible.

This object is achieved according to the invention by a method with which in claim 1 Features specified or a device with the in claim 12 specified features solved.

The invention is based on the basic idea of the cooling system and thus connected variably drivable coolant pump depending on one of the engine regulate the amount of fuel supplied. With the invention, the performance of the Coolant pump over a range between preferably zero to one maximum pumping capacity (l / h) either continuously or in a variety of stages can be set variably. In that the supplied to the internal combustion engine Amount of fuel related to engine warming can be Regulation of the coolant pump and thus the cooling of the engine with foresight take place on the basis of the fuel currently consumed. The function of the Heat input from the engine into the coolant to fuel mass flow is largely similar for all combustion concepts. This has the advantage that the cooling system or the coolant pump can be controlled according to the polluter and not just how known from the prior art, the sluggish by temperatures in the cooling circuit are and are only effects of an engine or vehicle operating point. On Another advantage is that a cooling control basically without sensors prone to failure or temperature measuring points is possible and these sensors or temperature measuring points may only be used in the following operating cases, namely warm-up, Hot idle or hot shutdown.

Advantageous refinements and developments are in the subclaims shown.

According to a preferred embodiment of the invention, the sum of the fuel quantity supplied since the ignition of the engine Σm ' _{KS is} compared with a so-called target fuel quantity m _target . If the setpoint is undershot, as is the case, for example, when the engine is cold started, the engine is not cooled by the cooling system first, unless with a volume flow requested for other needs in the cooling system, for example for a heater. This has the advantage that the warm-up phase of the engine can be shortened and the fuel consumption can be reduced, in contrast to engines in which the coolant pump is connected to the crankshaft. In these engines, the coolant pump is automatically driven when the engine is started, so that the engine is cooled before it warms up.

If the sum of the supplied fuel quantity Σm ' _KS exceeds the specified target value m _target , cooling takes place by switching on the coolant pump. The performance of the coolant pump is determined as a function of at least one of the following parameters, such as engine speed nMot, engine load, outside temperature and / or an average over a predetermined time interval (for example 30 seconds) of the fuel quantity m ' _KS . By averaging the coolant pump speed over time, pressure threshold loads can be avoided, which leads to a lower load on the cooling system and the coolant pump, such as a water pump.

The cooling system and the coolant pump are preferably additionally regulated as a function of the coolant temperature. For this purpose, in addition to the comparison of the quantity of fuel supplied, the instantaneous temperature of the coolant T _{Mot is} compared with a _desired coolant temperature T _Soll . If the target value T _{target is} exceeded, the engine is cooled by the cooling system, the output of the coolant pump being determined as described above as a function of the engine speed nMot, the engine load, the outside temperature and / or an average value of the fuel quantity m ' _KS can. This has the advantage that the operating point of the coolant pump can be variably adjusted depending on certain parameters such as the outside temperature or the load. This operation is particularly advantageous when the engine is hot idling and the engine is turned off.

Additionally or alternatively, the cooling system and the coolant pump can be regulated depending on the engine oil temperature. For this purpose, in addition to the comparison of the quantity of fuel supplied, the coolant temperature, the instantaneous engine oil temperature T _{Oil is} compared with a _target engine oil temperature T _Soll . If the value _falls below the target value T _target , there is no cooling by the coolant pump, unless with a volume flow requested for other needs in the cooling system, for example for a heater. Furthermore, the cooling starts as soon as the _target engine oil temperature T _{target is} exceeded. The performance of the coolant pump is determined as a function of the engine speed nMot, the engine load, the outside temperature and / or an average of the fuel quantity m ' _KS .

Since in addition to the coolant pump, the operation of additional equipment such as an air conditioner, a separate heater or an automatic transmission to the engine Extracts heat and / or supplies, the cooling system is preferably controlled additionally depending on the connection or the heat input of such Facility. This is preferably dependent on a degree of connection For example, the heater determines the performance of the coolant pump. An advantage is, that the pump meets the requirements of the additional facilities is operated, even if this would not be necessary for cooling the motor. This is, for example, for supplying the heating or cooling of the automatic transmission e.g. the case when idle. An additional one may not be necessary Water pump for heating. According to the degree of connection of the heating, for example, approximately 100%, the performance of the coolant pump increased accordingly so that this part of the coolant to the heat exchanger the heater can pump. If no heating is switched on, the one previously determined is determined Maintain coolant pump performance.

Furthermore, the control system compares a first coolant temperature threshold value with the current coolant temperature T _Mot . If the threshold value is exceeded, the coolant pump is operated at a predetermined power at least within a predetermined time interval, so that the engine is cooled further. This has the advantage that the engine is adequately cooled by the ambient temperature even when it is running hot or when it is additionally heated.

To ensure reliable cooling when the engine is switched off after a heavy load enable it is determined whether the engine is switched off. Exceeds that Coolant temperature a second coolant temperature threshold, so the coolant pump with a predetermined power within a predetermined Time interval operated and the engine cooled. This has the advantage that the engine continues is cooled and so temperature peaks in the engine after the engine has stopped high load can be prevented. The duration of the wake depends on the temperature is exceeded to the setpoint, but a defined duration is not may be exceeded (battery discharge). When falling below the second Coolant temperature threshold, there is no further cooling by the Cooling system.

If it is determined that the engine is in operation, the control loop is closed and again a calculation of the pump performance based on the amount of fuel supplied performed to achieve continuous cooling of the engine.

Figur 1 ein Ablaufdiagramm für ein bevorzugtes Regelverfahren gemäß der Erfindung.

An embodiment of the invention will be described with reference to the following drawing. It shows:

Figure 1 is a flowchart for a preferred control method according to the invention.

In the control method according to the invention shown in FIG. 1, it is first determined whether the engine is in operation. In this case, the sum of the fuel quantity since the ignition of the engine Σm ' _{KS is} compared with a predetermined target value m _{target of} the fuel quantity. In a further query, the current temperature of the coolant T _{Mot is} compared with a target temperature T _{Soll of} the coolant.

If one of the values falls below the corresponding setpoint, i.e. is the sum of the Fuel has not been sufficient to keep the engine on since the engine started To warm up operating temperature or the engine does not have the necessary Operating temperature reached, the coolant pump is initially not operated, it unless with a volume flow requested for other needs in the cooling system for example for a heater. This will remove heat from the engine prevented and the engine warms up quickly. In the case where If one of the setpoints is exceeded, cooling begins. This is the performance the coolant pump as a function of an average of the fuel quantity in one certain time interval (e.g. 30 seconds), the engine speed and / or the engine load certainly. Other parameters such as the operating parameters of the cooling system are here also conceivable.

As already mentioned above, the coolant pump can be operated when a Volume flow for other needs in the cooling system is requested for example for a heater. The regulation of the performance of the coolant pump depends on the activated heating has priority over the control depending on whether the Setpoint values for the fuel quantity or the coolant temperature are below or exceeded become.

In a further step, it is determined whether a heater is switched on and depending on the performance of the coolant pump regulated. With an activated Heating removes heat from the engine in which at least part of the heated Coolant is pumped to the heater and there via a heat exchanger Vehicle interior is discharged. Depending on the degree of connection of the heating the output of the coolant pump is regulated accordingly. Is the heating too close? 100% switched on, the pump output is increased accordingly to a value of for example V'Pumpe = 2200l / h. If only 40% of the heating is switched on, then the pump output of the coolant pump is correspondingly lower and is, for example V'pump = 1500 l / h. In the event that the heating is not switched on, the remains Keep the previously determined pump output of the coolant pump unchanged. This Embodiment of the invention has the particular advantage that under certain circumstances no separate pump for the heating circuit is required. In addition to heating additionally or alternatively other elements which, when switched on or be switched on, extract heat from an engine and / or supply it for control the coolant pump. This can be done in a comparable way as with heating via the degree of connection or heat input (loss).

In a further step it is determined whether the coolant has a first, upper Coolant temperature threshold (e.g. 115 ° C) exceeds, for example by Hot idle. If this is the case, the pumping power of the coolant pump is below a predetermined value sufficient for cooling that Pump power increased to this predetermined value and in a predetermined Time interval cooled further. If the threshold is undershot, the performance remains the coolant pump unchanged.

The next step is to determine whether the engine is still operating. In this If the control circuit closes, the pump power is recalculated based on the amount of fuel supplied to ensure continuous cooling of the engine guarantee.

If the engine is switched off, it is monitored whether a second, lower coolant temperature threshold value (e.g. 100 ° C) is exceeded by the coolant in order to Stopping the engine after high load (hot shutdown) ensures reliable cooling guarantee. In this case, the coolant pump cools the engine with a predetermined power in a predetermined time interval of preferably 60-300 Seconds. If the second coolant temperature threshold is undershot, this is done no further cooling.

By considering special cases such as hot stopping, a cold start with or without heating and hot idling is aimed at to meet the requirements of heating and component temperatures, and by suppressing forced convection, the heat transfer is minimal hold and thus to get faster component heating. The absolute The temperature level of the cooling system is still regulated by a thermostat. This can be used as a conventional thermostat with an expansion element (heated as Map thermostat or unheatable) or as an electrical actuator his. An electrically operated coolant pump is preferably used Coolant pump used, which has its own drive. As a coolant preferably cooling water used. All values mentioned here for the Pump output, temperatures and time intervals are only examples.

Claims (22)

Method for controlling a cooling system of an internal combustion engine, wherein the performance of a coolant pump depending on one of the The amount of fuel supplied to the internal combustion engine is adjustable. A method according to claim 1, characterized in that a target fuel quantity m _{target is} specified, which is compared with the sum of the fuel quantity since the ignition of the internal combustion engine Σm ' _KS , and no cooling by the coolant pump takes place if the value falls below the target value m _target and wherein the coolant pump is operated with an adjustable output when the setpoint is exceeded. Method according to Claim 1 or 2, characterized in that the coolant _{pump is} regulated as a function of the temperature of the coolant T _Mot , a set temperature of the coolant T _{Soll being} predefined which is compared with the temperature of the coolant T _Mot and no cooling by the coolant pump takes place when the value _falls below the target value T _Soll and the coolant pump is operated with an adjustable output when the target value is exceeded. Method according to one of claims 1 to 3, characterized in that the coolant pump is controlled as a function of the temperature of the engine oil T _Oil , a target engine oil temperature being specified which is compared with the temperature of the engine oil T _Oil and wherein no cooling by the coolant pump takes place when the setpoint is undershot and the coolant pump is operated with an adjustable output when the setpoint is exceeded. Method according to claim 2, 3 or 4, characterized in that the adjustable output of the coolant pump is determined by at least one of the parameters such as the mean value of the fuel quantity m ' _KS over a predetermined time interval, the engine speed, the engine load and / or the outside temperature. Method according to one of claims 1 to 5, characterized in that the output of the coolant pump is regulated as a function of the connection of an additional device which can extract and / or supply heat to the internal combustion engine, this regulation having priority over the output of the coolant pump. A method according to claim 6, characterized in that this device is a heating and / or air conditioning and / or an automatic transmission. Method according to Claim 7, characterized in that the output of the coolant pump can be set depending on the degree of connection of the heating, the output preferably being at least 2200 l / h at 100% degree of connection. Method according to Claim 7 or 8, characterized in that the output of the coolant pump can be set as a function of the heat input from the automatic transmission, the pump output being added to the pump output required for cooling the internal combustion engine. Method according to one of claims 1 to 9, characterized in that when the coolant temperature exceeds a first coolant temperature threshold value of, for example, 115 ° C, the coolant pump is operated at least within a predetermined time interval with a predetermined output of preferably about 2000 l / h. Method according to one of claims 1 to 10, characterized in that when the engine is switched off and the coolant temperature exceeds a second coolant temperature threshold value of, for example, 100 ° C, the coolant pump with a predetermined output of preferably about 1500 l / h within a predetermined Time interval operated. Device for controlling a cooling system of an internal combustion engine with a control device for controlling the output of a coolant pump in Dependence on a fuel quantity supplied to the internal combustion engine. Apparatus according to claim 12, characterized in that the control device controls the coolant pump so that no cooling takes place if a sum of the fuel quantity since the ignition of the internal combustion engine Σm ' _KS falls below a predetermined target fuel quantity m _target and operates the coolant pump with an adjustable output, if the setpoint is exceeded. Apparatus according to claim 12 or 13, characterized in that the control device controls the coolant pump so that no cooling takes place when the temperature of the coolant T _Mot falls below a predetermined target temperature of the coolant T _Soll and operates the coolant pump with an adjustable output when the target value is exceeded is. Device according to one of claims 12 to 14, characterized in that the control device controls the coolant pump so that no cooling takes place when the temperature of the engine oil T _Oil falls below a predetermined engine oil target temperature and operates the coolant pump with an adjustable output when the target value is exceeded is. Apparatus according to claim 13, 14 or 15, characterized in that the adjustable output of the coolant pump is dependent on at least one of the parameters such as the mean value of the fuel quantity m ' _KS over a predetermined time interval, the engine speed, the engine load and / or the outside temperature. Device according to one of claims 12 to 16, characterized in that the control device regulates the output of the coolant pump as a function of the connection of an additional device which can extract and / or supply heat to the internal combustion engine, this control of the output of the coolant pump primarily depending on the Control device is carried out. Apparatus according to claim 17, characterized in that this device is a heating and / or air conditioning and / or an automatic transmission. Apparatus according to claim 17 or 18, characterized in that the control device controls the output of the coolant pump depending on the degree of connection and / or the heat input of the device. Apparatus according to claim 17 or 18, characterized in that the control device regulates the output of the coolant pump for a specific time interval depending on the degree of connection of the device. Device according to one of claims 12 to 20, characterized in that the control device operates the coolant pump at least within a predetermined time interval with a predetermined power when the coolant temperature exceeds a first coolant temperature threshold. Device according to one of claims 12 to 20, characterized in that the control device operates the coolant pump with a predetermined power within a predetermined time interval when the engine is switched off and the coolant temperature exceeds a second coolant temperature threshold value.

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