Rotary piston adjuster having a torsion spring

Abstract

A rotary piston adjuster for an internal combustion engine that includes an outer rotor which can be drive-connected to a crankshaft, an inner rotor which can be connected to a camshaft, and a torsion spring which is connected to the outer and inner rotors. The rotors can be adjusted rotationally about a common rotational axis, and a rotary angle position of the inner rotor with respect to the outer rotor can be adjusted by means of a hydraulic actuating mechanism. The torsion spring is connected by way of a hook-shaped first end section to a first connecting element which is connected in a rotationally fixed manner to the inner rotor. A pair of first supporting elements are connected to the inner rotor for supporting the torsion spring, which first supporting elements are arranged at an angular spacing in a range from 90° to 270° from the first connecting element.

Description

TECHNICAL FIELD[0001]The invention is in the technical field of internal combustion engines and generally relates to a rotary piston adjuster for an internal combustion engine.BACKGROUND OF THE INVENTION[0002]In internal combustion engines with a mechanical valve actuating mechanism, gas exchange valves are actuated by the cams of a camshaft which is driven by a crankshaft, it being possible to use the arrangement and the shape of the cams to fix the control times of the valves for a defined phase relation between the crankshaft and the camshaft. The control times of the valves can be influenced via a change in the phase relation between the crankshaft and the camshaft as a function of the instantaneous operating state of the internal combustion engine, as a result of which advantageous effects can be achieved, such as a reduction in fuel consumption and pollutant generation. The use of special apparatuses for optionally adjusting the phase relation between the crankshaft and the ca...

AI Technical Summary

Benefits of technology

[0002]In internal combustion engines with a mechanical valve actuating mechanism, gas exchange valves are actuated by the cams of a camshaft which is driven by a crankshaft, it being possible to use the arrangement and the shape of the cams to fix the control times of the valves for a defined phase relation between the crankshaft and the camshaft. The control times of the valves can be influenced via a change in the phase relation between the crankshaft and the camshaft as a function of the instantaneous operating state of the internal combustion engine, as a result of which advantageous effects can be achieved, such as a reduction in fuel consumption and pollutant generation. The use of special apparatuses for optionally adjusting the phase relation between the crankshaft and the camshaft is sufficiently well known, which special apparatuses are usually called “camshaft adjusters”.

[0003]In general, camshaft adjusters comprise a drive part which is drive-connected to the crankshaft via a drive wheel, an output part which is fixed to the camshaft, and an actuating mechanism which is connected between the drive part and the output part, which activating mechanism transmits the torque from the drive part to the output part and makes it possible to adjust and fix the phase relation between the two.

[0004]In a conventional design as a hydraulic rotary piston adjuster, the drive part is configured as an outer rotor and the output part is configured as an inner rotor, the outer and inner rotors being arranged concentrically with regard to a common rotational axis and such that they can be adjusted rotationally with respect to one another. In the radial intermediate space between the outer and inner rotors, at least one pressure space is formed by one of the two rotors, into which pressure space a vane which is connected to the respectively other rotor extends, as a result of which the pressure space is divided into a pair of pressure chambers which act counter to one another. The outer and inner rotors can be rotated relative to one another by targeted pressure loading of the pressure chambers, in order to bring about a change in the phase relation between the crankshaft and the camshaft as a result. Similarly, a phase relation can be maintained by hydraulic stressing.

[0005]Alternating torques then occur on the camshaft during the operation of the internal combustion engine, which alternating torques, in the case of insufficient pressure medium supply, as is the case, for example, during the starting phase or when idling, lead to the inner and outer rotors being moved with respect to one another in an uncontrolled manner. This can have the result that the vanes strike to and fro within the pressure spaces, as a result of which wear is increased and unpleasant noise is caused. In addition, the phase relation between the crankshaft and the camshaft varies to a pronounced extent in this case, with the result that the internal combustion engine does not start or runs uneasily.

[0006]In order to avoid this, hydraulic rotary piston adjusters are equipped with a locking device for the rotationally fixed locking of the outer and inner rotors, locking taking place in a phase relation which is denoted as a basic position and is favorable thermodynamically for starting the internal combustion engine. The selection of the basic position depends on the concrete design of the internal combustion engine and can be an early, late or intermediate position, the late position corresponding to maximum adjustment of the inner rotor in the trailing direction, the early position corresponding to maximum adjustment of the inner rotor in the leading direction and the intermediate position corresponding to a rotary angle position between said two end rotary positions, in relation to the rotational direction of the camshaft. A rotary angle position of the inner rotor relative to the outer rotor which is situated at least approximately in the middle between the early and the late position is denoted as middle position. In a corresponding way, adjustment of the inner rotor in the direction of the early position is called early adjustment, and adjustment in the opposite direction is called late adjustment.

[0007]The locking device for locking the outer and inner rotors in the basic position in a rotationally fixed manner typically comprises one or more bolts which are received in one of the two rotors, can be moved, in the basic position, into positively locking engagement with the respectively other rotor and can be unlocked hydraulically in order to release the rotational adjustability of the outer and inner rotors.

Problems solved by technology

Alternating torques then occur on the camshaft during the operation of the internal combustion engine, which alternating torques, in the case of insufficient pressure medium supply, as is the case, for example, during the starting phase or when idling, lead to the inner and outer rotors being moved with respect to one another in an uncontrolled manner.

This can have the result that the vanes strike to and fro within the pressure spaces, as a result of which wear is increased and unpleasant noise is caused.

A disadvantage of the arrangement which is shown in FIG. 3A is, in particular, the fact that, in the case of a wraparound angle of approximately 180° of the inner hook 106, the radial installation space requirement is increased on account of the doubly placed inner winding 113.

In addition, a rotational center (not denoted in greater detail) of the helical spring 105 lies outside the common rotational axis 114 of the arrangement, with the result that an unbalance occurs in an undesirable way on account of the eccentricity of the helical spring 105 caused by this.

However, the four-cornered shaft 115 increases the radial installation space requirement of the arrangement in an undesirable manner, and the manufacturing costs for the camshaft adjuster 101 increase as a result of the greater material requirement for the helical spring 105.

However, in industrial serial production, the shaping of the journal 116 requires an additional manufacturing step for turning and / or milling of the inner rotor 103 and / or for the attachment of an additional component on the inner rotor 103, as a result of which the manufacturing costs for the rotary piston adjuster 101 are increased.

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