METHOD FOR STARTING AN INTERNAL COMBUSTION ENGINE

Abstract

A method for starting an internal combustion engine, having which has at least one cylinder, a controllable starter and a controllable fuel injection device, at least one cylinder, in particular every cylinder, of the internal combustion engine being assigned at least one decompression valve for reducing the compression which takes place during the operation of the internal combustion engine in the case of a compression stroke. A defined starting rotational speed is predetermined in the control unit, that, in the case of a controlled activation of the starter, the at least one decompression valve is opened in an automatically controlled manner by means of a control unit, and that the control unit detects the current rotational speed of the internal combustion engine and, when the defined starting rotational speed is reached, closes the at least one decompression valve and activates the fuel injection device.

Claims

1. A method for starting an internal combustion engine, which has at least one cylinder, a controllable starter and a controllable fuel injection device, at least one cylinder, in particular every cylinder, of the internal combustion engine being assigned at least one decompression valve for reducing the compression which takes place during the operation of the internal combustion engine in the case of a compression stroke, the method comprising predetermining in a control unit a defined starting rotational speed; automatically opening the at least one decompression valve in an controlled manner by means of the control unit, during a controlled activation of the starter; and detecting the current rotational speed of the internal combustion engine and, when the defined starting rotational speed is reached, closing the at least one decompression valve and activating the fuel injection device. in that the control unit

2. The method according to claim 1, characterized in that the internal combustion engine is a multiple-cylinder diesel internal combustion engine.

3. The method according to claim 2, wherein the multiple-cylinder diesel internal combustion engine is a drive engine of a commercial vehicle.

4. The method according to claim 1, wherein the starting rotational speed lies in a rotational speed range of from 100 rpm to 180 rpm.

5. The method according to claim 1, wherein the at least one decompression valve is configured as a solenoid valve and is controlled electrically.

6. The method according to claim 1, wherein the starter and the fuel injection device can likewise be controlled by means of the control unit.

7. The method of according to claim 6, wherein the control unit is integrated at least partially into an engine control unit.

8. The method according to claim 1, wherein the starter is configured as a starter generator.

9. The method according to claim 8, wherein the starter generator can be operated using 48 Volts.

10. The method according to claim 9, wherein, at least one electrically drivable auxiliary unit of the internal combustion engine is supplied with electric drive energy by the starter generator.

11. The method according to claim 10, wherein the at least one electrically drivable auxiliary unit is an electrically drivable water pump,

12. The method according to claim 8, wherein the starter generator is integrated into the gear train of the internal combustion engine.

13. The method according to claim 12, wherein the starter generator is integrated into a gear train with a high transmission ratio.

14. The method according to claim 13, wherein the starter generator has a gearwheel as drive element which is in tooth engagement with a gearwheel of the gear train.

15. The method according to claim 1, wherein during the operation of an internal combustion engine with a controllable cylinder switch-off means, the decompression valve of at least one switched off cylinder is opened in a controlled manner in a further function for pressure generation for a pneumatic component which is connected to the decompression valve.

16. The method according to claim 1, wherein the at least one decompression valve is assigned to a cylinder head of the internal combustion engine.

17. An apparatus for starting an internal combustion engine comprising: an internal combustion engine including at least one cylinder; a controllable starter and a controllable fuel injection device in communication with the at least one cylinder; a decompression valve assigned to the at the least one cylinder, the decompression valve reducing the compression which takes place during the operation of the internal combustion engine in the case of a compression stroke; and a control unit defines a predetermined rotational speed, wherein upon a controlled activation of the starter, the at least one decompression valve is opened in an automatically controlled manner by means of the control unit, and wherein the control unit detects the current rotational speed of the internal combustion engine and, when the defined starting rotational speed is reached, closes the at least one decompression valve and activates the fuel injection device.

18. A vehicle, comprising: an internal combustion engine including at least one cylinder; a controllable starter and a controllable fuel injection device in communication with the at least one cylinder; a decompression valve assigned to the at the least one cylinder, the decompression valve reducing the compression which takes place during the operation of the internal combustion engine in the case of a compression stroke; and a control unit defines a predetermined rotational speed, wherein upon a controlled activation of the starter, the at least one decompression valve is opened in an automatically controlled manner by means of the control unit, and wherein the control unit detects the current rotational speed of the internal combustion engine and, when the defined starting rotational speed is reached, closes the at least one decompression valve and activates the fuel injection device.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0024] FIG. 1 is a flow chart depicting the method of the present disclosure.

DETAILED DESCRIPTION

[0025] The disclosure will be described in further detail by way of example using FIG. 1.

[0026] The single FIGURE shows a flow chart 1 of the starting method according to the disclosure, as is realized, for example, for a multiple-cylinder diesel internal combustion engine in a commercial vehicle.

[0027] In accordance with status rectangle 2, a driver in the driver's cab actuates a starting operating element for engine starting, for example by way of an ignition key.

[0028] As a result, in accordance with status rectangle 3, a control unit is actuated which activates a starter generator for an engine drive. At the same time, the decompression valves of the individual cylinders are opened. In contrast, the fuel injection device is not yet activated.

[0029] In the decision diamond 4, a check is made by the control unit as to whether the rotational speed which rises by way of activation of the starter generator has reached a starting rotational speed which is predetermined in the control unit.

[0030] If this is the case, in accordance with status rectangle 5, the control unit closes the decompression valves and activates the fuel injection device, with the result that the internal combustion engine reacts and starts in accordance with status rectangle 6, after which the starter function of the starter generator is switched off and a switchover is carried out to the generator function.

LIST OF DESIGNATIONS

[0031] 1 Flow chart [0032] 2 Status rectangle [0033] 3 Status rectangle [0034] 4 Decision diamond [0035] 5 Status rectangle [0036] 6 Status rectangle