Internal-combustion engines – Poppet valve operating mechanism – With means for varying timing
Reexamination Certificate
2002-04-16
2003-02-11
Denion, Thomas (Department: 3748)
Internal-combustion engines
Poppet valve operating mechanism
With means for varying timing
C123S090120, C123S090150, C123S090160, C123S090270, C123S090310, C251S012000, C251S213000, C464S001000, C464S002000, C464S160000
Reexamination Certificate
active
06516763
ABSTRACT:
FIELD OF THE INVENTION
The invention concerns a method of actuating a device for varying the valve timing of an internal combustion engine, which method can be advantageously implemented particularly in all types of camshaft adjusting devices having a hydraulically releasable start locking.
BACKGROUND OF THE INVENTION
Such a method relates particularly to camshaft adjusting devices of the generic type disclosed in DE-OS 197 26 300. These devices, generally designated in the technical field as axial piston and rotary piston adjusting devices, are arranged, irrespective of their structure, on the drive-side end of a camshaft mounted in the cylinder head of the internal combustion engine while being generally configured as hydraulic adjusting drives that comprise an element fixed in driving relationship to the crankshaft of the internal combustion engine and an element rotationally fixed to the camshaft. The element fixed to the crankshaft is in power-transmitting relationship with the element fixed to the camshaft through at least one hydraulic working chamber configured within the device, each hydraulic working chamber being divided by an adjusting element within the device into a so-called. A pressure chamber and a B pressure chamber. A pivoting or fixing of the element fixed to the camshaft relative to the element fixed to the crankshaft is effected by a selective or a simultaneous pressurizing of the A and/or B pressure chamber of each hydraulic working chamber, the pressurizing of the pressure chambers being controlled by an electromagnetically actuated valve piston of a hydraulic valve whose solenoid is actuated by a microprocessor as a function of different operation parameters of the internal combustion engine. Normally, this valve piston of the hydraulic valve permits, in a non-energized or low energized state of the solenoid, a pressurization of the B pressure chamber of each hydraulic working chamber, in a high or maximum energized state of the solenoid, a pressurization of the A pressure chamber of each hydraulic working chamber, and in a central position, a holding of the pressure medium pressure in both pressure chambers of each hydraulic working chamber of the device. When the internal combustion engine has been switched off and the volume of the A pressure chamber of each hydraulic working chamber is minimized, the element fixed to the camshaft can be mechanically coupled to the element fixed to the crankshaft in a preferred basic position for starting the internal combustion engine, coupling be achieved by an additional locking element arranged on the element fixed to the camshaft or on the element fixed to the crankshaft, which locking element can be displaced by a spring element into a coupling position within a complementary reception in the element fixed to the crankshaft or in the element fixed to the camshaft. This complementary reception of the locking element is hydraulically connected to the pressure medium supply to the volume-minimized A pressure chamber of at least one hydraulic working chamber of the device, so that, upon pressurization of the volume-minimized A pressure chamber of each hydraulic working chamber during starting of the internal combustion engine, the reception of the locking element is likewise pressurized and the locking element is displaced hydraulically, against the force of its spring element, into an uncoupling position.
This shock-like pressurization of the volume-minimized A pressure chamber generally effected by a short pulse on the solenoid at maximum energization has proved to be a drawback in practice because the sudden rise of pressure in all the volume-minimized A pressure chambers causes a bracing moment to act on the locking element which leads to a jamming of the locking element in its coupling position particularly when the mean moment of drag of the camshaft acts in the same direction as the bracing moment and/or when the time for building up the bracing moment is shorter than the time for displacing the locking element into its uncoupling position. As a consequence, a relative rotation between the element fixed to the camshaft and the element fixed to the crankshaft into a defined angle given by the microprocessor is no longer possible, so that, for example, in the case of inlet-side camshaft adjusting devices there are performance deficits of the internal combustion engine, and in the case of outlet-side camshaft adjusting devices, the internal combustion engine has higher emission values.
OBJECT OF THE INVENTION
The object of the invention is therefore to provide a method of actuating a device for varying the valve timing of an internal combustion engine, particularly a camshaft adjusting device having a hydraulically releasable start locking, which method enables a reliable prevention of a jamming of the locking element in its coupling position even when a bracing moment resulting from a pressurization and a mean moment of drag of the camshaft impede movement of the locking element in the same direction.
SUMMARY OF THE INVENTION
The invention achieves this object in a camshaft adjusting device having a hydraulically releasable start locking, said device generally comprising following features:
the device (
1
) is arranged on the drive-side end of a camshaft (
3
) mounted in the cylinder head of the internal combustion engine and generally configured as a hydraulic adjusting drive,
said device (
1
) comprising an element (
4
) fixed in driving relationship to a crankshaft of the internal combustion engine and an element (
5
) rotationally fixed to the camshaft (
3
),
the element (
4
) fixed to the crankshaft is in powder-transmitting relationship with the element (
5
) fixed to the camshaft through at least one hydraulic working chamber (
6
) formed within the device (
1
),
each hydraulic working chamber (
6
) of the device (
1
) is divided by an adjusting element (
7
) within the device (
1
) into a pressure chamber (
8
) and a pressure chamber (
9
),
a pivoting or fixing of the element (
5
) fixed to the camshaft relative to the element (
4
) fixed to the crankshaft is effected by a selective or a simultaneous pressurizing of the pressure chamber (
8
,
9
) of each hydraulic working chamber (
6
),
the pressurizing of pressure chamber (
8
,
9
) of each hydraulic working chamber (
6
) is regulated by an electromagnetically actuated valve piston of a hydraulic valve (
10
) whose solenoid (
11
) is actuated by a micro processor (
12
) as a function of different operation parameters of the internal combustion engine,
the valve piston of the hydraulic valve (
10
) permits, in a non-energized or low energized state of the solenoid (
11
), a pressurization of the pressure chamber (
9
), in a high or maximum energized state of the solenoid (
11
), a pressurization of the pressure chamber (
8
), and in a central position, a holding of the pressure medium pressure (P) in both pressure chambers (
8
,
9
) of each hydraulic working chamber (
6
) of the device (
1
),
when the internal combustion engine has been switched off and the volume of the pressure chamber (
8
) of each hydraulic working chamber (
6
) has been minimized, the element (
5
) fixed to the camshaft can be mechanically coupled to the element (
4
) fixed to the crankshaft in a preferred basic position for starting the internal combustion engine,
the mechanical coupling is achieved by a locking element (
13
) arranged on the element (
5
) fixed to the camshaft or on the element (
4
) fixed to the crankshaft, which locking element (
13
) can be displaced by a spring element (
14
) into a coupling position within a complementary reception (
15
) in the element (
4
) fixed to the crankshaft or in the element (
5
) fixed to the camshaft,
the complementary reception (
15
) of the locking element (
13
) is hydraulically connected to the pressure medium supply (
16
) to volume-minimized pressure chamber (
8
) of at least one hydraulic working chamber (
6
) of the device (
1
),
upon pressurization of the volume-minimized pressure chamber (
8
) of each hydraulic work
Bierman, Muserlian and Lucas
Chang Ching
INA Walzlager Schaeffler oHG
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