Method for starting an internal combustion engine

• US 20080216787A1
• Filed: 08/29/2007
• Published: 09/11/2008
• Est. Priority Date: 08/29/2006
• Status: Abandoned Application

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Wolber, Jens, Kroepke, Karsten, Streib, Martin, Weiss, Ruediger, Crepin, Pierre-Yves, Djon, Jean-Marc Tonye, Dietrich, Manfred, Lederle, Karl-Bernhard, Walz, Matthias, Mariappan, Niraimathi Appavu
• Application Number:
  US11/897,601
• Publication Number:
  US 20080216787A1
• Time in Patent Office: Days
• US Class Current: 123/179.3
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60L 2240/445 Temperature
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 2510/0676 Engine temperature
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2710/0622 Air-fuel ratio
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: F02D 41/047 Taking into account fuel evaporation or wall wetting; special correction after fuel cut-off F02D41/126
• CPC Class Codes: F02D 41/062 for starting F02D41/061 takes precedence
• CPC Class Codes: F02N 2300/102 Control of the starter motor speed; Control of the engine speed during cranking
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

To achieve a reliable and exhaust-optimized combustion starting already from the beginning of a combustion phase in the startup of an internal combustion engine, the internal combustion engine is brought to a target speed by an electric motor in a drag phase, the target speed being higher than the previously known starting speed. The target speed corresponds approximately to an idling speed assigned to the internal combustion engine, for example. After exceeding the starting speed, first a mixture enrichment is determined, taking into account a prevailing state of a wall film here in particular. Only after reaching the target speed is the fuel metered and does the combustion take place in the combustion phase. The fuel is metered here in particular on the basis of the mixture enrichment determined after exceeding the starting speed.

Claims

1. A method for starting an internal combustion engine, the method comprising:

activating an electric motor after a shut-down phase, and the internal combustion engine is brought to a starting speed by the electric motor;

bringing the internal combustion engine to a target speed by the electric motor in a drag phase, the target speed being higher than the starting speed and at least approximately corresponding at least to an idling speed;

determining a mixture enrichment after exceeding the starting speed; and

performing fuel metering, taking into account the determined mixture enrichment after reaching the target speed in a combustion phase.

2. The method of claim 1, wherein the mixture enrichment is determined as a function of one of a measured duration of the shut-down phase, a measured duration of the drag phase, the target speed, and a measured temperature.

3. The method of claim 1, wherein the mixture enrichment is determined as a maximum possible value.

4. The method of claim 1, wherein the mixture enrichment is determined as a function of a prevailing torque demand.

5. The method of claim 1, wherein the mixture enrichment is reduced in the combustion phase one of continuously and in increments.

6. The method of claim 5, wherein the mixture enrichment is reduced, taking into account one of the prevailing value of the mixture enrichment, the target speed, a measured prevailing speed, a measured duration of the combustion phase, a measured prevailing torque demand, and a measured temperature of the internal combustion engine.

7. The method of claim 1, wherein the target speed is determined as a function of one of a prevailing vehicle electrical system voltage, a prevailing torque demand, a measured temperature of the internal combustion engine, and a measured duration of the shut-down phase.

8. The method of claim 1, wherein the target speed is higher than an idling speed.

9. The method of claim 1, wherein the internal combustion engine is operable in a coasting phase and enrichment of the mixture is performed in a reinstatement phase after the coasting phase, and wherein the mixture enrichment is determined in the same manner as the enrichment of the mixture during the reinstatement phase.

10. A control unit for controlling or regulating an internal combustion engine, the internal combustion engine being associated with an electric motor which is activatable after a shut-down phase and which brings the internal combustion engine to a starting speed, the control unit comprising:

an arrangement to start the internal combustion engine by performing the following;

activating the electric motor after a shut-down phase, and the internal combustion engine is brought to a starting speed by the electric motor;

bringing the internal combustion engine to a target speed by the electric motor in a drag phase, the target speed being higher than the starting speed and at least approximately corresponding at least to an idling speed;

determining a mixture enrichment after exceeding the starting speed; and

performing fuel metering, taking into account the determined mixture enrichment after reaching the target speed in a combustion phase.

11. An internal combustion engine system which is associated with an electric motor which is activatable after a shut-down phase, and which brings the internal combustion engine to a starting speed, comprising:

a control arrangement to start the internal combustion engine by performing the following;

activating the electric motor after a shut-down phase, and the internal combustion engine is brought to a starting speed by the electric motor;

bringing the internal combustion engine to a target speed by the electric motor in a drag phase, the target speed being higher than the starting speed and at least approximately corresponding at least to an idling speed;

determining a mixture enrichment after exceeding the starting speed; and

performing fuel metering, taking into account the determined mixture enrichment after reaching the target speed in a combustion phase.

12. The internal combustion engine of claim 11, wherein a hybrid drive is provided by cooperation of the internal combustion engine and the electric motor.

13. A computer readable medium having a program that is executable by a processor arrangement in a control unit, comprising:

program code for controlling or regulating an internal combustion engine, the internal combustion engine being associated with an electric motor which is activatable after a shut-down phase and which brings the internal combustion engine to a starting speed, by performing the following;

activating the electric motor after a shut-down phase, and the internal combustion engine is brought to a starting speed by the electric motor;

bringing the internal combustion engine to a target speed by the electric motor in a drag phase, the target speed being higher than the starting speed and at least approximately corresponding at least to an idling speed;

determining a mixture enrichment after exceeding the starting speed; and

performing fuel metering, taking into account the determined mixture enrichment after reaching the target speed in a combustion phase.

14. The computer readable medium of claim 13, wherein the computer program is stored in a memory element assigned to the processor arrangement, the memory element including one of a random-access memory (RAM), a read-only memory (ROM), a flash memory, an optical memory medium and a magnetic memory medium.