Method and auxiliary control unit for cold start optimization of an internal combustion engine

Abstract

The present invention relates to a method (100) for cold start optimization of an internal combustion engine (10) comprising: determining (110) a start of an engine preheating device (12); transmitting (115) a selected coolant temperature T.sub.cool_trans to an engine control unit (14); and adapting (140) the selected coolant temperature T.sub.cool_trans transmitted to the engine control unit (14) to a current coolant temperature T.sub.coll_current during a time interval Δt following the start of the internal combustion engine (10). The present invention further relates to an auxiliary control unit (22) which is configured to execute the method (100).

Claims

1. Method for cold start optimization of an internal combustion engine comprising: determining, by an auxiliary control unit, a start of an engine preheating device; transmitting, by the auxiliary control unit, a selected coolant temperature T.sub.cool_trans to an engine control unit, wherein the selected coolant temperature T.sub.cool_trans differs from a current coolant temperature T.sub.cool_current during a time interval Δt following the start of the internal combustion engine; and adapting, by the auxiliary control unit, the selected coolant temperature .sub.cool_trans transmitted to the engine control unit to the current coolant temperature T.sub.cool_current during the time interval Δt following the start of the internal combustion engine.

2. Method according to claim 1, wherein detecting a temperature T takes place when the engine preheating device starts.

3. Method according to claim 2, wherein setting of the selected coolant temperature T.sub.cool_trans transmitted to the engine control unit occurs when the internal combustion engine starts in dependence of the detected temperature T.

4. Method according to claim 3, wherein setting of the selected coolant temperature T.sub.cool_trans transmitted to the engine control unit to the temperature T detected when the engine preheating device starts takes place when the internal combustion engine starts.

5. Method according to claim 1, wherein setting of the selected coolant temperature T.sub.cool_trans transmitted to the engine control unit to a fixed value T.sub.fix takes place when the internal combustion engine starts.

6. Method according to claim 1, wherein the engine preheating device heats coolant of a cooling circuit of the internal combustion engine after its start and heats a vehicle interior with the aid of the heated coolant.

7. Method according to claim 1, wherein the time interval Δt begins with the start of the internal combustion engine.

8. Method according to claim 1, wherein the time interval Δt lasts a maximum of one minute, preferably between 10 seconds and 30 seconds.

9. Method according to claim 1, wherein adapting of the coolant temperature T.sub.cool_trans transmitted to the engine control unit to the current coolant temperature T.sub.cool_current takes place uniformly and linearly during the time interval Δt.

10. Method according to claim 1, wherein adapting of the coolant temperature T.sub.cool_trans transmitted to the engine control unit to the current coolant temperature T.sub.cool_current takes place immediately when the current coolant temperature T.sub.cool_current exceeds an admissible maximum value T.sub.max.

Description

(1) The drawings show:

(2) FIG. 1 a flow chart of an inventive method; and

(3) FIG. 2 a schematic representation of vehicle components involved in the method according to the disclosure.

(4) FIG. 1 shows a flow chart of an inventive method. The method 100 according to the disclosure starts with the determining 110 of a start of an engine preheating device. The engine preheating device may, for example, be designed to preheat only an internal combustion engine of a vehicle, in particular a car or a truck, by means of the used coolant. The engine preheating device can additionally or primary have the function of an auxiliary heater, which also heats a vehicle interior with the aid of the heated coolant of the internal combustion engine.

(5) Subsequent to detecting the start of the engine preheating device, detecting 120 of the temperature T can be optionally performed when the engine preheating device starts. For example, the detected temperature T may be an ambient temperature or a current coolant temperature when the engine preheating device starts. The ambient temperature and the current coolant temperature are usually almost the same when the internal combustion engine is cold started. Deviations between the ambient temperature and the current coolant temperature when the engine preheating device starts can optionally be used for errdiagnosis of the used temperature sensors by a device carrying out the method. Subsequent to the detecting 120 of the temperature T when the engine preheating device starts, a setting 130 of a selected coolant temperature T.sub.cool_trans transmitted to the engine control unit to the temperature T previously detected when the engine preheating device starts can be performed. It is also possible to determine a fixed temperature T.sub.fix as the selected coolant temperature T.sub.cool_trans. It is also possible to determine the selected coolant temperature T.sub.cool_trans to be transmitted as function of the temperature T previously recorded.

(6) The engine control unit controls and regulates the operation of the internal combustion engine. Thus, the current coolant temperature is not transmitted to the engine control unit, but, for example, the temperature T recorded when the engine preheating device is started, which over time is significantly below a current coolant temperature T.sub.cool_trans due to the operation of the engine preheating device. When the combustion engine is started, adapting 140 of the selected coolant temperature T.sub.cool_trans transmitted to the engine control unit to a current coolant temperature T.sub.cool_current takes place during a time interval Δt following the start of the internal combustion engine. In this way, it is possible to prevent an error memory entry caused by an implausibly high coolant temperature and a possible emergency operation of the internal combustion engine due to a supposedly defective temperature sensor. When the adapting 140 of the temperature transmitted to the engine control unit has been completed, the method 100 ends and the engine control unit can control and regulate the operation of the internal combustion engine independently in the proven manner without further influence.

(7) FIG. 2 shows a schematic representation of vehicle components involved in the method according to the present disclosure. Indicated is an internal combustion engine 10, an engine preheating device 12, a vehicle interior 18, a cooling device 24, and a sensor 26. A cooling circuit 16 with coolant 20 connects the above mentioned components to one another in a conventional manner, the coolant 20 being heated during operation of the internal combustion engine 10 and heat being discharged into the vehicle's environment at the cooling device 24, which represents the heat exchanger. A circulation of the coolant 20 in the cooling circuit 16 is indicated by the arrows. The coolant 20 can also dissipate a part of the heat absorbed by the combustion engine 10 to the vehicle interior 18 via a heat exchanger which is not explicitly shown. Further, the engine preheating device 12 can heat the coolant 20 independently of the internal combustion engine. The engine preheating device 12 can therefore be used to preheat both the combustion engine 10 and the vehicle interior 18. The sensor 26 is also in contact with the cooling circuit 16 and, as indicated, can transmit a recorded current coolant temperature to an auxiliary control unit 22. In addition or alternatively, the auxiliary control unit 22 can also receive an ambient temperature from a further sensor 28, which is detected by the further sensor 28. The auxiliary control unit 22 can modify the recorded temperature value(s) and forward them to an engine control unit 14 of the internal combustion engine 10. For example, the auxiliary control unit 22 can set a recorded temperature value T when the engine preheating device 12 starts and, independent from a current cooling temperature value T.sub.cool_current of the coolant 20 during operation of the engine preheating device 12, transmit this temperature value T to the engine control unit 14 until the combustion engine 10 is started. The set value may be, for example, a fixed value T.sub.fix or a temperature value determined as a function of a temperature value T detected when the engine preheating device 12 starts.

(8) By starting the internal combustion engine 10, a time interval Δt can be started during which the auxiliary control unit 22 adapts the temperature value T.sub.cool_trans transmitted to the engine control unit 14 to the current temperature value T.sub.cool_current of the coolant. The adaption can, for example, be carried out continuously and linearly, the adaption can also be carried out rapidly, for example if the currently recorded temperature value T.sub.cool_current of the coolant exceeds a fixed threshold value T.sub.max. The initial setting and the adapting of the temperature value T.sub.cool_trans transmitted to the engine control unit later on can be done, for example, by an adjustable ohmic resistor which modifies the voltage representing the temperature value. A variable resistor integrated in the auxiliary control unit 22 may, for example, be connected between the engine control unit 14 and the sensor 26 in case of auxiliary heating. Depending on the input parameters, the resistance value of the variable resistor can be adjusted such that the total resistance value of the sensor 26 and of the variable resistor corresponds to the resistance of the sensor 26 without heating by the engine preheating device. During the adjustment in the time interval Δt, the resistance value of the variable resistor can be reduced to 0 ohm so that the engine control unit detects the current temperature. When retrofitting the vehicle with the engine preheating device 12, the auxiliary control unit 22 can be easily inserted into the line connection between the engine control unit 14 and the sensor 26, 28, for example. Further modifications to the vehicle's electronic may not be necessary. When the engine preheating device 12 is inactive, the variable resistor will not affect the temperature sensing either. It is also possible to avoid an extensive modification of the cooling circuit 16, for example, a separation of the internal combustion engine 10 from the cooling circuit 16 via a shut-off valve during operation of the engine preheating device 12 as an auxiliary heater (isolated operation).

(9) The features which are disclosed in the above description, in the drawings, and in the claims can be used for realizing the disclosed devices and methods both individually and in any combination.

REFERENCE NUMERALS

(10) 10 internal combustion engine 12 engine preheating device 14 engine control unit 16 cooling circuit 18 vehicle interior 20 coolant 22 auxiliary control unit 24 cooling device 26 sensor 28 further sensor 100 method 110 determining 115 transmitting 120 detecting 130 setting 140 adapting