CN107091186B

CN107091186B - Method for preparing a motor start and electric motor for carrying out said method

Info

Publication number: CN107091186B
Application number: CN201710087181.XA
Authority: CN
Inventors: D.黑尔德; M.舒马歇尔; O.格伦特; S.韦尔茨
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2016-02-18
Filing date: 2017-02-17
Publication date: 2022-02-15
Anticipated expiration: 2037-02-17
Also published as: CN107091186A; DE102016202534A1

Abstract

The invention relates to a method for preparing a motor start. Wherein the crankshaft (2) of the combustion motor (1) which is switched off is fixed during the adjustment of at least one camshaft (3, 4) of the combustion motor (1). The invention further relates to an electric motor, which can be coupled to a combustion motor (1). The electric motor is designed to: the crankshaft (2) of the combustion motor (1) is held in a predetermined position.

Description

Method for preparing a motor start and electric motor for carrying out said method

Technical Field

The invention relates to a method for preparing a motor start. Furthermore, the invention relates to a computer program which is set up for: each step of the method is carried out and the invention relates to a machine-readable storage medium on which the computer program is stored. The invention further relates to an electronic control unit, which is set up to: the motor start is prepared by means of the method. Finally, the invention relates to an electric motor which can be used in the method.

Background

The direct-injection otto motor can be started without a starter by means of what is known as a direct start. The direct start option is used in particular in motors with a start/stop system. In order to increase the reliability of the direct start, the camshaft of the motor can be adjusted relative to the crankshaft of the motor by means of a hydraulic or electromechanical camshaft phase adjuster before the direct start in the following manner: so that the compression degree of the next cylinder to be compressed does not become too high. This makes it possible to: the ignition top dead center (ZOT) can be reliably exceeded.

Disclosure of Invention

In a method for preparing a motor start, in particular a direct start, a crankshaft of a combustion motor, in particular an Otto motor, which is shut down is fixed when at least one camshaft of the combustion motor is adjusted, so that said crankshaft can no longer rotate. In the case of combustion motors optimized with regard to friction, the relatively high torque caused by the valve spring can result in: in preparation for starting the motor, not only is at least one camshaft adjusted, i.e., twisted, but the crankshaft is twisted together at this time. This can be prevented by fixing the crankshaft during the adjustment of at least one camshaft.

In one embodiment of the method, a starter is engaged in a starter ring gear of the combustion motor for fixing the crankshaft. In this case, the starter motor of the starter is not set in rotation. This can be achieved by energizing only the starter's relay. This measure increases the torque that prevents the crank mechanism of the crankshaft from twisting. Thus, when the camshaft adjuster is actuated, only the camshaft is twisted without twisting the crankshaft.

In a further embodiment of the method, an electric motor coupled to the combustion motor is actuated in order to fix the crankshaft in the following manner: so that the electric motor holds the crankshaft in a predetermined position. The electric motor can be a starter in particular. The coupling between the electric motor and the combustion motor can then be effected in the manner described above by engaging the starter in the starter ring gear. In this case, however, not only is the torque passively increased, but the starter motor actively holds the crankshaft in its original position. To this end, the starter motor is energized in such a way that it counteracts the torsional movement of the crankshaft caused by the camshaft adjuster.

However, the crankshaft can also be fastened in the same way using other electric motors coupled to the combustion motor. If, in a hybrid vehicle, the combustion motor is mechanically coupled to an electric motor provided for propelling the vehicle, a fastening of the crankshaft of the combustion motor can likewise be achieved by suitable actuation of the electric motor.

In a further embodiment of the method, an oil circuit of the combustion motor is interrupted downstream of an oil pump of the combustion motor for fixing the crankshaft. The oil pump of the combustion motor is driven by the crankshaft of the combustion motor in the following way: the crankshaft gear is connected with the oil pump gear through a control chain. By interrupting the oil circuit, a rotational movement of the oil pump and thus also of the oil pump gear is prevented. The oil pump gear prevents a torsional movement of the crankshaft by its mechanical coupling to the crankshaft and thus fixes the crankshaft.

The computer program is set up for: each step of the method is carried out, in particular when the computer program is run on a computing instrument or an electronic controller. To this end, the computer program is stored on the machine-readable storage medium.

By loading the computer program onto a conventional electronic control unit, an electronic control unit is created which is designed to: preparing for starting the motor in the following manner: the crankshaft of the combustion motor which is switched off is fixed during the adjustment of at least one camshaft of the combustion motor.

The electric motor can be coupled with a combustion motor, in particular a starter. The electric motor is designed to: the crankshaft of the combustion motor is held in a predetermined position. For this purpose, the electric motor can be operated in particular in the following manner: so that the electric motor resists torsional movement applied thereto.

Drawings

An embodiment of the invention is shown in the drawings and is further described in the following description. In the drawings:

fig. 1 schematically shows an assembly of a combustion motor, the motor start of which can be prepared by means of an embodiment of the method according to the invention;

fig. 2 shows a cross-sectional view of the combustion motor according to fig. 1; and is

Fig. 3 shows an electric motor configured as a starter according to an embodiment of the invention.

Detailed Description

Fig. 1 shows a combustion motor 1 in the form of a direct injection otto motor. The combustion motor has a crankshaft 2 and two camshafts 3, 4. An oil pump 5 is arranged in an oil circuit 6 of the combustion motor 1. A shut-off valve 61 effects a shut-off of the oil circuit 6 downstream of the oil pump 5. The electronic control unit 7 is designed to: controls the components of the combustion motor 1.

Shown in fig. 2: how a crankshaft gear 21 arranged at the crankshaft 2 drives the control chain 8 of the combustion motor 1. Two

camshaft gears

31, 41 engage into the control chain 8 and thereby transmit the rotational movement of the crankshaft 2 to the two camshafts 3, 4. Further, an oil pump gear 51 is fitted into the control chain 8, so that the oil pump 5 can be driven by the rotational motion of the crankshaft 2.

The combustion motor 1 has a starter 9. The starter is shown in fig. 3. The starter 9 is an electric motor having a starter gear 91. The starter 9 can be engaged into the starter ring gear 11 of the combustion motor by energizing a starter relay in the following manner: so that the starter gear 91 is fitted into the starter ring gear 11. This enables a conventional start-up of the combustion motor 1.

In order to carry out a direct start of combustion motor 1, the fuel/air mixture contained in the cylinders of combustion motor 1 is ignited without having previously engaged starter 9 in starter ring gear 11 and with crankshaft 2 in rotation by means of starter ring gear 91. However, for this purpose, it is necessary to bring the valve drive of the combustion motor 1 into a phase in which the cylinders of the combustion motor do not achieve full compression. Otherwise, the torque of the first firing may be insufficient to deliver the second cylinder of the combustion motor 1 past the ignition top dead center.

In one embodiment of the method according to the invention, the direct start is prepared for this purpose in the following manner: the two camshafts 3, 4 are adjusted relative to the crankshaft 2 by means of the camshaft phase adjuster in such a way that an optimum degree of compression is achieved for the direct start. Since the two

camshaft gears

31, 41 are coupled to the crankshaft gear 21 via the control chain 8, the following risks exist in this case: the crankshafts 2 are twisted together. To prevent this, the crankshaft 2 is fixed in its current position in preparation for the direct start. This is achieved by engaging the starter 9 into the starter ring gear 11. The starter 9 is configured in the following manner: so that the starter can be actuated by the control unit 7 in order to hold the crankshaft 2 in its current position. That is to say, the torque acting on crankshaft gear 21 via control chain 8 must on the one hand overcome the torque generated by engaging starter gear 91 in starter ring gear 11 and, on the other hand, must also overcome the reverse movement of starter 9. Thereby preventing the crankshaft 2 from twisting.

In the present exemplary embodiment of the method according to the invention, the shut-off valve 61 is additionally closed when the camshafts 3, 4 are adjusted, so that no more oil can circulate in the oil circuit 6. This prevents a rotational movement of the oil pump 5, so that the oil pump gear 51 can no longer move. Since the oil pump gear is coupled to the crankshaft gear 21 via the control chain 8, this makes it possible to additionally fix the crankshaft 2 in its current position.

Once the adjustment of the two camshafts 3, 4 is completed, the fixing of the crankshaft 2 is cancelled by: so that the starter 9 is disengaged from the starter ring gear 11 again and the shut-off valve 61 is opened. This ensures that the free rotatability of the crankshaft 2 is again ensured when the motor is started.

Claims

1. Method for preparing the starting of a combustion motor (1), wherein a crankshaft (2) of a shut-down combustion motor (1) is fixed during the adjustment of at least one camshaft (3, 4) of the combustion motor (1).

2. Method according to claim 1, characterized in that a starter (9) is engaged in a starter ring gear (11) of the combustion motor (1) for fixing the crankshaft (2).

3. Method according to claim 1 or 2, characterized in that for fixing the crankshaft (2) an electric motor coupled to the combustion motor (1) is operated in the following manner: so that the electric motor holds the crankshaft (2) in a predetermined position.

4. A method according to claim 3, characterized in that said electric motor is a starter (9).

5. Method according to claim 1 or 2, characterized in that the oil circuit of the combustion motor (1) is interrupted downstream of the oil pump (5) of the combustion motor in order to fix the crankshaft.

6. A machine-readable storage medium, on which a computer program is stored, which computer program is set up for: carrying out each step of the method according to any one of claims 1 to 5.

7. An electronic control unit (8) which is set up for: the start-up of the combustion motor (1) is prepared by means of the method according to any one of claims 1 to 5.

8. Electric motor which can be coupled with a combustion motor (1), characterized in that the electric motor is set up for: when the combustion motor (1) is switched off and at least one camshaft (3, 4) of the combustion motor (1) is adjusted, a crankshaft (2) of the combustion motor (1) is held in a predetermined position.

9. The electric motor according to claim 8, characterized in that the electric motor is a starter (9).