EP1504172B1 - Camshaft adjuster with an electrical drive - Google Patents

Description

The invention relates to a device for releasably connecting and adjusting the camshaft and the crankshaft of an internal combustion engine, in particular according to the preamble of claim 1.

Background of the invention

To an internal combustion engine with hydraulic or electric Nokkenwellenverstell system to ensure a safe engine start must the camshaft are in the so-called basic or emergency position. In the case of intake camshafts, this is usually "late", with outlet camshafts in "early". During normal operation of the vehicle, the camshaft when the engine is switched off, it is moved to the respective base position and fixed or locked there.

Conventional, hydraulically actuated rotary piston adjusters, such as Flügelzeller, Swing or segmented wings have a locking unit. These fixes the hydraulic adjuster in its base position until it is sufficient Has built oil pressure for adjusting the camshaft. Does it come to stalling? of the engine, the camshaft may be in an undefined position outside the base position.

For hydraulic camshaft adjusting systems with the basic position in "late", the camshaft will be at the next start of the engine and the lack of oil pressure due to the Nockenwellenreibmoments, the against the direction of the camshaft, automatically moves to the late base position adjusted. If the base position is in "early", the camshaft must Lack of oil pressure against the Nockenwellenreibmoment in the early base position be adjusted. This is usually done with the help of a balance spring, the one equal to the Nockenwellenreibmoment but opposite Moment generated.

These usual in hydraulically actuated camshaft adjusters methods to reach the base positions after stalling the internal combustion engine are not applicable to electrically driven camshaft adjusters. They are not required as long as the variable motor system is intact and the camshaft even when the internal combustion engine or can revert to the respective base position when restarting. For electrical However, variable displacement motor systems can be the variable motor and / or its Control fail and thereby prevent the achievement of the base position.

In DE 41 10 195 A1 discloses a device for releasably connecting and adjusting describes the camshafts and the crankshaft of an internal combustion engine, with a trained as a three-shaft gear adjustment, the one crankshaft-connected drive shaft, a camshaft-connected Output shaft and connected to an electric variable motor Has adjusting shaft, wherein between the input and output shaft at a standstill Adjusting a stationary gear ratio io is present, the height of the Transmission type (negative or positive gear) and the adjustment direction of the camshafts determined who have a basic or emergency position.

This adjustment is a smooth and accurate adjustment the camshaft position sought. So in case of failure of the variable displacement engine system the function of the internal combustion engine maintained at least makeshift can be, a limitation of the adjustment is provided. A note upon reaching the base or emergency position in such a case is missing however.

Object of the invention

The invention is therefore based on the object, an electric camshaft adjuster to create, in which the camshaft even in case of failure of Adjusting motor and / or the same control in its base position adjustable is.

Summary of the invention

According to the invention, the object is solved by the features of patent claim 1. After deceleration or setting of the adjusting be adjusted by turning the drive shaft in the low idle of the engine or - if it was strangled - when restarting the same, even with failed Verstellmotor system, the camshaft in its basic or emergency position. In this position, the vehicle can be started and operated with certain restrictions, so that a workshop can be achieved. Prerequisite is a suitable stationary gear ratio i ₀ , by the desired transmission type (plus or minus) and the adjustment (late or early) is determined.

In the selection of the adjusting negative or positive gear come into question. With positive stationary gear ratio i ₀ , the input and output shafts have the same direction of rotation, with negative stationary gear ratio io opposite directions of rotation, based on a stationary adjusting and related components.

If the adjusting shaft is held in a negative gear and rotates the Drive shaft clockwise, so the output shaft rotates and thus the Camshaft counterclockwise, which corresponds to a retardation.

Is in a plus gear with a stationary gear ratio io> 1, the adjusting shaft held and rotated the drive shaft clockwise, so the output shaft rotates slower than the drive shaft, that is, contrary clockwise and thus in the direction of retardation.

If the adjusting shaft is held in a positive gear with a stationary gear ratio 0 <i ₀ <1 and the drive shaft rotates clockwise, the output shaft rotates faster than the drive shaft, that is, in the clockwise direction and thus in the direction of advance.

These conditions are applicable to all eligible adjustment. In summary, if the adjustment motor has failed to reach a late base position, the setting of the adjusting shaft of a negative gear with i ₀ <0 or a plus gear with i ₀ > 1 and to reach an early base position fixes the adjusting shaft of a plus gear with 0 <i ₀ <1 required are.

It is advantageous that the adjusting motor with a permanent magnet rotor has a passive self-holding moment, which from a middle position in both directions of rotation rise to a maximum and then fall again. The increased by the converted friction torque of the variable transmission Self-holding torque of the adjusting motor must be only 60% - 100% of the converted maximum dynamic camshaft torque retroactively acting on the adjusting shaft because the energy content of the tips of the camshaft torque is low and the necessary holding torque more through the mean camshaft torque is determined. The use of a permanent magnet rotor has the advantage over a permanent magnet stator that the current only has to be conducted into the cylinder-head-fixed stator.

With insufficient self-holding torque of a Permanentmagnetverstellmotors and in externally excited DC motors without latching torque serves an additional braking torque for fixing the adjusting shaft. This is powered by a cylinder head, preferably mechanical or eddy current brake generated. The brakes are in low idle of the engine automatically activated and automatically released when the adjusting motor is in operation. In this way, the camshafts before stopping the engine always adjusted to their base position. Should this be by stalling If the engine is not possible, it will be rescheduled at the next start.

It has proven to be advantageous that the adjustment speed of the camshaft is preferably between 30 ° and 60 ° cam angle per second due to the selected stationary gear ratio i ₀ with stationary adjusting and low idle speed of the engine. It is irrelevant whether the adjusting motor adjusted when returning the camshaft in its base position in one or two directions of rotation.

It is necessary that in the control position of the camshafts the drive, output and and adjusting shafts of the adjusting rotate at the same speed. In this way, there is no relative movement between the crankshaft and the camshafts.

As adjustment, for example, come known eccentric or wave gear (Positive gear) or wobble or double planetary gear (minus or plus gearbox) in question and the adjusting motors are as usual brushless Permanent magnet rotor motors or as brush-mounted external excitation DC motors trained.

Brief description of the drawings

Figur 1

ein Verstellgetriebe mit einem Verstellmotor, dessen Stator zylinderkopffest ist;

Figur 2:

ein anders Verstellgetriebe mit einem anderen Verstellmotor, dessen anderer Stator mit umläuft.

Further features of the invention will become apparent from the following description and the drawing in which an embodiment of the invention is shown schematically. Show it:

FIG. 1

an adjusting with an adjusting motor whose stator is cylinder head fixed;

FIG. 2:

another variable with another variable displacement motor whose other stator rotates with.

Detailed description of the drawings

In Figures 1 and 2 are adjusting 1, 1 'with electric adjusting motors 2, 2 'shown, for adjusting the rotational angle position between the not shown crankshaft and the camshaft 3, 3 'of an internal combustion engine serve.

The adjusting 1, 1 'is designed as a three-shaft gear, with a drive shaft 4, 4 ', an output shaft 5, 5' and an adjusting shaft 6, 6 '.

The drive shaft 4, 4 'is connected to a drive wheel 7, 7' and via this means a gear, not shown, or toothed belt or a toothed chain firmly connected to the crankshaft.

The output shaft 5, 5 'is connected to the camshaft 3, 3' and the adjusting shaft 6, 6 'with the rotor 8, 8' of the adjusting motor 2, 2 'in a fixed connection.

The stator 9 of the adjusting motor 2 is fixedly connected to the cylinder head 10 and stands still, the stator 9 'of the adjusting motor 2' is connected to the drive wheel 7 ' firmly connected and rotated as the adjusting 1 with half crankshaft speed.

The camshaft 3, 3 'has a base or emergency running position, the for a safe start and limited operation must be achieved. This succeeds intact adjustment motor 2, 2 'even after a stalling of the engine without difficulty, since the adjusting motor 2, 2 'the camshaft 3, 3 'with the internal combustion engine or during the restart adjusted to the base position. But it also has to be with failed adjustment motor 2, 2 'a restart may be possible to at least one workshop to reach.

The adjusting gears 1, 1 'and their stationary gear ratio io are designed to that merely by setting the adjusting shafts 6, 6 ', the camshafts 3, 3 'get into their base position when starting and the internal combustion engine so that it remains bootable.

With stationary adjusting shaft 6, 6 'and right-handed drive shaft 4, 4' applies to the interpretation of io:

At i ₀ <0 there is a minus transmission with retardation; at 0 <i ₀ <1 a plus gear with advance adjustment and at io> 1 a plus gear with late adjustment.

The setting of the adjusting 6 can by a de-energized variable motor 2 with permanent magnet rotor 8 or permanent magnet stator 9 done. The adjusting motor 2 has a self-holding torque that of a central position off in both directions up to a maximum and after falls again. The self-holding torque is the maximum torque, with which one can statically load a non-energized variable motor, without one to cause nonuniform but continuous rotation.

The self-holding torque is due to the converted friction torque of the variable speed 1 reinforced to the cogging torque, which is between 60% and 100% of the converted maximum, dynamic camshaft torque at low Idle speed of the engine should be.

Is sufficient the cogging torque of the de-energized adjusting motor 2 for setting the adjusting shaft is not characterized by a cylinder head, mechanically or electrically acting brake 11 additionally applied an external braking torque. This acts equal to the cogging torque in both directions of rotation of the adjusting 6th

After a stalling of the internal combustion engine or after failure of the adjustment motor 2, the camshaft 3 may be in an undefined position. By setting or hard braking the adjusting 6, the camshaft 3 on the subsequent start by that caused by the starter Rotary movement of the drive shaft 4 adjusted in its base position, so that a start is possible.

Since the stator 9 'of the adjusting motor 2' (see Figure 2) with its rotor 8 ' mitrotiert is a setting of the adjusting shaft 6 'by a between stator 9' and rotor 8 'effective self-holding torque not possible. In this case can the adjusting shaft 6 'only by a cylinder head fixed, mechanical or electrical Brake 11 'be braked. With the same is after a stall the internal combustion engine or in the event of failure of the adjusting motor 2 'at the latest at the next engine start an adjustment of the camshaft 3 'in its base position and thus also allows an engine start.

When the adjusting motors 2, 2 'have high temperatures, the mechanical serves or electrical stalling of the adjusting shafts 6, 6 'also for thermal relief of the adjusting motors 2, 2 '.

LIST OF REFERENCE NUMBERS

1

variator

1'

variator

2

electric adjusting motor

2 '

electric adjusting motor

3

camshaft

3 '

camshaft

4

drive shaft

4 '

drive shaft

5

output shaft

5 '

output shaft

6

adjusting

6 '

adjusting

7

drive wheel

7 '

drive wheel

8th

rotor

8th'

rotor

9

stator

9 '

stator

10

cylinder head

10 '

cylinder head

11

Cylinder-head-resistant brake

11 '

Cylinder-head-resistant brake

Claims (9)

1. Device for the releasable connection and adjustment of the camshaft (3, 3') and the crankshaft of an internal combustion engine, having an adjusting mechanism (1, 1') in the form of a triple gearing, which has a drive shaft (4, 4') connected to the crankshaft, an output shaft (5, 5') connected to the camshaft and an adjusting shaft (6, 6') connected to an electric servomotor (2, 2'), the drive shaft (4, 4') the output shaft (5,5') and the adjusting shaft (6, 6') of the adjusting mechanism (1, 1') rotating at the same speed in the regular position of the camshaft (3, 3'), and a gearing transmission ratio i₀, the level of which determines the type of gearing (negative or positive gearing) and the adjustment direction of the camshaft (3, 3'), which has an emergency running position, being situated between the drive shaft (4, 4') and the output shaft (5, 5') when the adjusting shaft (6, 6') is stationary, characterized in that the emergency running position of the camshaft (3, 3') can be attained by braking of the adjusting shaft (6, 6') and by rotation of the drive shaft (4, 4'), together with a suitable gearing transmission ratio i₀, should the servomotor (2, 2') and/or its control fail.
2. Device according to Claim 1, characterized in that a negative gearing of i₀<0 or a positive gearing of i₀>1 are suitable for retarding the camshaft (3, 3') and a positive gearing of 0<i₀<1 for advancing the camshaft (3, 3').
3. Device according to Claim 2, characterized in that the self-locking torque of a servomotor (2), which has a rotor (8) and a stator fixed to the cylinder head, the rotor (8) preferably being equipped with permanent magnets, is suitable for non-energized arresting of the adjusting shaft (6).
4. Device according to Claim 3, characterized in that 60% to 100% of the converted, maximum dynamic torque of the camshaft fed back to the adjusting shaft (6) can be achieved, at least in starting and at low idling speed of the internal combustion engine, through a corresponding design of the servomotor (2) and by increasing its self-locking torque by the converted moment of friction of the adjusting mechanism (1).
5. Device according to Claim 4, characterized in that provision is made for the aforementioned braking by an external braking moment of a mechanical or electrical brake (11, 11') fixed to the cylinder head in the absence of sufficient self-locking torque from the servomotor (2, 2').
6. Device according to Claim 5, characterized in that the brakes (11, 11') are automatically actuated at low idling speed of the internal combustion engine and are automatically released when the servomotors (2, 2') are operating.
7. Device according to Claim 6, characterized in that the rate of adjustment of the camshaft (3, 3') on the basis of the selected gearing transmission ratios i₀ with the adjusting shaft (6, 6') stationary and the internal combustion engine running at idling speed is preferably between 30° and 60° camshaft angle per second.
8. Device according to Claim 7, characterized in that the camshaft (3, 3') is returned to its emergency running position irrespective of the direction of rotation of the servomotor (2, 2').
9. Device according to Claim 8, characterized in that the adjusting mechanism (1, 1') takes the form, for example, of an eccentric mechanism or shaft mechanism (positive gearing) or a swashplate mechanism or double planetary gear mechanism (negative or positive gearing), and the servomotor (2, 2') takes the form of a brushless or brush direct current motor.

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