EP1521899B1 - Electrically driven camshaft adjuster - Google Patents

Abstract

The invention relates to an electrical device for adjusting the position of the angle of rotation of a camshaft (3) relative to the crankshaft of an internal combustion engine. Said device comprises an adjusting gear unit (1) that is embodied as a triple-shaft gear system, an input part (4) that is fixed to the crankshaft, an output part (5) that is fixed to the camshaft, and an adjusting shaft (6) that is connected in a torsion-proof manner to an electric adjusting motor (2) which is provided with a permanent magnet rotor (8) and a stator that is fixed to a housing. A stationary gear ratio (i0), the value of which defines the type of the adjusting gear unit (1) as a positive or negative gear unit and determines whether the direction of adjustment of the camshaft (3) is into a basic advanced or retarded position, is disposed between the input part (4) and the output part (5) when the adjusting shaft (6) is at rest. Due to an adequate constructional design of the adjusting gear unit (1), stationary gear ratios (i0) can be achieved, by means of which a basic advanced or retarded position of the camshaft (3) can be obtained exclusively by braking the adjusting shaft (6) when the adjusting gear unit (1) rotates, the adjusting shaft (6) preferably being braked by short-circuit braking the adjusting motor (2).

Description

Field of the invention

The invention relates to an adjusting device for the rotational angular position of the camshaft to the crankshaft of an internal combustion engine, in particular according to the preamble of patent claim 1.

Background of the invention

To ensure safe engine start-up in an internal combustion engine with hydraulic or electric camshaft adjuster, the camshaft must be in a specific base position relative to the crankshaft when starting the engine. This is usually "late" for the intake camshaft and "early" for the exhaust camshaft.

During normal operation of the vehicle, the camshaft is driven regulated when stopping the engine in the respective base position and fixed there or locked. Serves in the electric camshaft adjustment, an electric adjusting motor and the hydraulic camshaft adjustment, a hydraulic Rotationskolbenversteller, which has a locking unit as a wing cell, swivel or wing aircraft. This fixes the hydraulic adjuster in its base position until, after the restart of the internal combustion engine, a sufficiently high oil pressure has built up for adjusting the camshaft.

When stalling the engine, however, a regulated adjustment of the hydraulic camshaft adjuster is impossible, so that the camshaft can be in an undefined position outside the base position.

For hydraulic camshaft adjusters with the base position in "late", the camshaft is automatically adjusted to the late base position at the next start of the engine and the lack of oil pressure due to the Nockenwellenreibmoments acting counter to the camshaft rotation. If the base position is "early", the camshaft must be adjusted to the early base position against the camshaft friction torque if there is no oil pressure. This is usually done with the help of a compensating spring, which generates a torque the Nokkenwellenreibmoment same but opposite.

These customary in hydraulic camshaft adjusters methods for reaching the base position after the stalling of the engine are not required for electrically driven camshaft adjusters, since the variable displacement motor can adjust the camshaft even when the engine is stationary or when starting in the respective base position. In electric camshaft phasers, however, the variable displacement motor and / or its control may fail, thereby preventing the attainment of the base or runflat position required for at least limited operation and restart.

vorliegt, deren Größe die Getriebegattung (Plus- oder Minusgetriebe) und die Verstellrichtung der Nockenwelle (früh- oder spätliegende Basisposition) bestimmt. Bei dieser Verstellvorrichtung wird eine leichtgängige und genaue Einstellung der Nockenwellenlage angestrebt. Damit bei Ausfall des Verstellmotor-Systems die Funktion des Verbrennungsmotors zumindest notdürftig aufrechterhalten werden kann, ist eine Begrenzung des Verstellwinkels vorgesehen. Ein Hinweis auf das Erreichen der Basis- bzw. einer Notlaufposition in einem solchen Fall fehlt jedoch.In the DE 41 10 195 A1 an electric adjusting device for the rotational angle position of the camshaft to the crankshaft of an internal combustion engine is described, with an adjusting, which is designed as a three-shaft gear and a crankshaft fixed drive member, a camshaft fixed output member and an adjusting shaft. The adjusting shaft is rotatably connected to an electric variable motor, which has a permanent magnet rotor and a stator fixed to the housing, wherein between the input and output part at a stationary adjusting a stationary gear ratio $${\mathrm{i}}_{\mathrm{0}}=\frac{{\mathit{Output\; teeth\; Z}}_{\mathit{northwest}}}{{\mathit{Output\; teeth\; Z}}_{\mathit{KW}}}$$

whose size determines the gear type (plus or minus) and the direction of adjustment of the camshaft (early or late base position). In this adjustment, a smooth and accurate adjustment of the camshaft position is desired. So that in case of failure of the adjusting motor system, the function of the internal combustion engine can be maintained at least makeshift, a limitation of the adjustment is provided. However, an indication of reaching the base or an emergency position in such a case is missing.

Object of the invention

The invention has for its object to provide an electric camshaft adjuster, which adjusts the camshaft in case of failure of the adjusting motor or its control or power supply in a simple manner and de-energized in their Notlauf- or base position.

Summary of the invention

Due to the structural design of the variable speed, the size of the stationary gear ratio i ₀ and thus determine the adjustment of the camshaft. The adjustment of the camshaft in the direction of the early or late base or emergency position takes place in case of failure of the adjusting motor or its power supply by merely braking the adjusting shaft with a rotating adjusting. This can be done during engine operation and during coasting or starting of the internal combustion engine. For the engine start and for low engine speeds, the base position of the camshaft is optimally suited and still possible for higher speeds, so that at least one workshop can be achieved in this way.
The deceleration of the adjusting can be done by a mechanical or an eddy current brake. However, these brakes require electrical power for their actuation. In contrast, the short-circuit brake according to the invention operates with short-circuit current, which is generated in the towed adjusting motor and so makes the short-circuit brake electrically self-sufficient. Since there is no mechanical friction, the short-circuit brake works wear-free.

In the selection of the adjusting negative or positive gear come into question. Minus transmission having a fixed transmission ratio i ₀ <0, plus gear a stationary gear ratio i _0> 0. If positive fixed transmission ratio i _0, the input and output shafts rotate in the same direction, with a negative stationary gear ratio i ₀ opposite directions of rotation relative to a stationary adjusting shaft and associated with this components.

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

If the adjusting shaft is held in a positive gear with a stationary gear ratio i ₀ > 1 and the drive shaft is rotated clockwise, the output shaft rotates slower than the drive shaft, that is, counterclockwise and thus also towards the base position "late".

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, ie in the clockwise direction and thus towards the base position "early". These conditions are applicable to all eligible three-shaft transmission.

It is advantageous that a double eccentric gear or a wobble gear and another double eccentric gear are provided as adjusting gear. Double eccentric gearboxes are characterized by low friction, simple construction and vibration-free operation.
An advantageous embodiment of the invention is that the double eccentric gear has a camshaft fixed lid, which is firmly connected with axial pins which engage in bores of two identically constructed spur gears with line contact and that the spur gears of the adjusting motor can be driven via a double eccentric shaft, mesh with a ring gear fixed ring gear.

The use of a standard standard clamping screw with a screw sleeve as the bearing surface for the rolling bearing of the double eccentric shaft offers cost advantages, but requires greater axial space. The plain bearing of identical design spur gears offers over a rolling bearing cost and space advantages with increased friction loss.

Another advantage is that the number of teeth Z _NW each of the two identical design spur gears (equal output teeth) smaller than the number of teeth Z _KW of crankshaft fixed ring gear (equal drive tooth number), resulting in a stationary gear ratio 0 <i ₀ <1. This stationary gear ratio causes in the present Pfusgetriebe and braking the adjusting a camshaft adjustment in the direction of "early", as is customary in Auslassnokkenwellen.

An advantageous development of the invention is that another Doppelexzentergetriebe has a crankshaft fixed drive wheel which is fixedly connected to axial pins which engage in holes of two identically constructed spur gears with line contact and that the identical design spur gears driven by the adjusting motor via a Doppelexzenterwelle are combing with a camshaft fixed ring gear.

With the storage of the double eccentric shaft on the cylindrical screw head of a central special clamping screw axial space is gained. Both solutions for the storage of the double eccentric shaft and the spur gears are suitable for both double eccentric gear.

It is also advantageous that the number of teeth Z _{NW of} the camshaft-fixed ring gear (equal output number) is greater than the number of teeth Z _KW of each of the identical design spur gears (equal drive teeth number), resulting in a stationary gear ratio i ₀ > 1.

The three phases of the adjustment cause a low-fluctuation torque curve of the adjusting motor at the same time low construction costs. The possibility of short-circuiting one, two or all three phases enables fine regulation of the short-circuit braking torque.

Since short-circuiting switches are provided which are closed when the adjusting motor is de-energized and open when the adjusting motor is energized, if the adjusting motor and / or its power supply fails, the fail-safe function of returning the camshaft to its basic or emergency running position occurs immediately. This also applies to the case of a stalled internal combustion engine whose camshaft position is corrected during the subsequent starting process.

To limit the temperature development of the adjusting motor, a clocked short-circuiting is also suitable. In this case, the short-circuiting switches are opened when a certain short-circuit current is reached and then automatically closed. This process is preferably controlled and operated by the short-circuit current itself, so that the clocking works even in case of failure of the adjusting motor or the power supply of the controller. The braking current can also be taken from active components, for example from an accumulator. The automatic closing is done, for example, by spring force.

To limit the high short-circuit currents, it is advantageous that a line resistance is arranged in the short-circuit lines.

It is also advantageous that an electronic current regulator operated with short-circuit current is provided in the short-circuit lines. This solution also works independently of the power supply of the adjustment motor.

Brief description of the drawings

Figur 1

eine Nockenwellenverstellvorrichtung, mit einem als Dreiwellengetriebe ausgebildeten Verstellgetriebe und einem elektrischen Verstellmotor, der einen gehäusefesten Stator aufweist;

Figur 2

ein Schaltschema eines dreiphasigen Gleichstromverstellmotors mit Kurzschlussleitungen und Kurzschlussschaltern;

Figur 3

ein Doppelexzentergetriebe mit einem kurbelwellenfesten Hohlrad;

Figur 4

ein Doppelexzentergetriebe mit einem nockenwellenfesten Hohlrad.

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

FIG. 1

a camshaft adjusting device, with a trained as a three-shaft gear adjusting mechanism and an electric adjusting motor having a housing fixed stator;

FIG. 2

a circuit diagram of a three-phase DC variable speed motor with short-circuit cables and short-circuiting switches;

FIG. 3

a double eccentric gear with a crankshaft fixed ring gear;

FIG. 4

a double eccentric gear with a camshaft-fixed ring gear.

Detailed description of the drawings

In FIG. 1 is a camshaft adjusting device with an adjusting gear 1 and an adjusting motor 2 shown schematically, which serves for adjusting the rotational angle position between a crankshaft, not shown, and a camshaft 3 of an internal combustion engine, not shown.

The adjusting gear 1 is designed as a three-shaft gear with a crankshaft fixed drive part 4 that has a drive wheel 7, a camshaft-fixed output part 5 and an adjusting shaft 6, which is rotatably connected to a permanent magnet rotor 8 of the adjusting motor 2. The adjusting motor 2 has a stator 9, which is fixedly arranged in a housing 10.

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

The adjusting gear 1 and its stationary gear ratio i ₀ are designed so that by simply braking the adjusting shaft 6, the camshaft 3 when starting the engine reaches its base position and the internal combustion engine is thereby startable.

When the adjusting shaft 6 is stationary and the driving part 4 is rotating clockwise, the following applies to the design of i ₀ :

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

In FIG. 2 a circuit diagram of the stator 9 of the adjusting motor 2 is shown. The adjusting motor 2 is designed as a brushless DC motor with three star-connected phases 11, the stator windings 12 and are supplied in phase by a controller 13 via control lines 15 with power.

The three phases 11 are connected by short-circuit lines 14 in the triangle. In the short-circuit lines 14 shorting switch 16 are provided, which are closed when de-energized adjusting motor 2 and open when energized variable motor 2. By closing the short-circuit switch 16 flows a short-circuit current, which is used for short-circuit braking of the adjustment motor 2 operated as a generator. The closing of the short circuit switch 16 can be done individually or as a whole, whereby the braking force is regulated.

Since too high a short-circuit current endangers the adjustment motor 2, a current limitation is required. This can be done by current-dependent opening of the short-circuit switch 16, which automatically when falling below a limit - for example, by spring force - close.

The short-circuit current can also be limited by power resistors 17 in the short-circuit lines 14. An electric current regulator 18, which is arranged in the short-circuit lines 14 and is fed by the short-circuit current, serves the same purpose.

In the Figures 3 and 4 are shown adjusting, which are designed as a three-shaft gear, with similar, but differently arranged components.

FIG. 3 shows a Doppelexzentergetriebe 19 with a crankshaft fixed sprocket 21, a camshaft fixed cover 25 and an adjusting shaft, which is designed as a double eccentric shaft 29. This is connected via a releasable keyway coupling 37 with an adjusting motor, not shown. Wedge, polygon, toothed, two-edged, square, and hexagonal shaft couplings are also conceivable as releasable couplings.

The camshaft-fixed cover 25 is clamped by means of a central standard clamping screw 31 via a clamping sleeve 30 with a camshaft pin 38 of a camshaft 65. An opening 66 of the keyway coupling 37 allows the access of a screwing tool to a screw head 36 of the central standard clamping screw 31.

The rotational angle position between the camshaft 65 and the camshaft fixed cover 25 is fixed by a fixing pin 39 which is arranged with an interference fit in aligned bores of the cover 25 and the camshaft pin 38.

The clamping sleeve 30 serves at the same time as a bearing surface for a needle sleeve 32 of the double eccentric shaft 29. This has two equal, but offset by 180 ° and thus fully balanced eccentric 67, which drive via friction bearing 33 two identically constructed spur gears 28. The spur gears 28 mesh with an internal toothing 22 of a crankshaft fixed ring gear 20, which is formed integrally with the sprocket 21.

The camshaft-fixed cover 25 has axial bores 63, in which pins 26 are pressed. These pass through axial bores 27 of the identical design spur gears 28 and project through axial bores 68 of a cover cover 34. The axial bores 63, 68 are arranged in alignment and are evenly spaced on a circle about the axis of rotation 64 of the camshaft adjuster. The axial bores 27 have a diameter greater by twice the eccentricity of the eccentric 67 than the pins 26, which have a line contact on the inner circumference of the axial bores 27.

The end cover 34 serves to complete the Doppelexzentergetriebes 19 and the axial fixation of the Doppelexzenterwelle 29, the spur gears 28 and the ring gear 20. It is axially fixed by retaining rings 35. These sit in grooves 78 which are arranged on the protruding from the axial bores 68 of the end cover 34 ends of the pins 26. The position of the grooves 78 determines the distance between the inner surfaces 79, 80 of the lid 25 and the end cover 34. In this case, the axial play required for the relative movement to the corresponding contact surfaces of the Doppelexzenterwelle 29, the spur gears 28 and the ring gear 20 is taken into account.

The ring gear 20 is mounted on the cover 25 in a sliding bearing 43 which, inter alia, receives the forces of the sprocket 21. This is formed integrally with the ring gear 20 and is connected via a chain with the crankshaft of the internal combustion engine in a rotationally fixed connection, from which it is driven at half the crankshaft speed. The drive torque of the sprocket 21 is transmitted via the spur gears 28 and the pins 26 on the cover 25 and the camshaft 65. The number of pins 26 depends on the height of the drive torque.

Ist im vorliegenden Fall die Drehzahl der Doppelexzenterwelle 29 zum Beispiel durch Kurzschlussbremsen des Verstellmotors kleiner als die des Kettenrads 21, so ist dessen Drehzahl niedriger als die der Nockenwelle 65, wodurch diese in Richtung "früh" verstellt.The lubrication of the Doppelexzentergetriebes 19 carried by engine lubricating oil. This passes from an inlet line 40 of the camshaft pin 38 in the needle sleeve 32 and from there by centrifugal force via radial lubricating oil holes 41 in plain bearings 33, in the axial bores 27, the internal teeth 22, the sliding bearing 43 and over completion holes 23, 24 in the engine compartment. The double eccentric shaft 29 is de-oiled by radial outflow holes 42. The double eccentric gear 19 is a plus gear, that is, the rotation direction of the sprocket 21 and the cam shaft 64 are the same. Since each of the spur gears 28 has a smaller number of teeth Z _NW than the number of teeth Z _{KW of} the crankshaft-fixed ring gear 20, a stationary gear ratio results: $${\mathrm{i}}_{\mathrm{0}}=\frac{{\mathit{Z}}_{\mathit{northwest}}}{{\mathit{Z}}_{\mathit{KW}}}0<i_0<1.$$

If, in the present case, the rotational speed of the double eccentric shaft 29 is smaller than that of the sprocket 21, for example due to short-circuit braking of the adjusting motor, its rotational speed is lower than that of the camshaft 65, as a result of which it adjusts in the "early" direction.

FIG. 4 shows another Doppelexzentergetriebe 44, with a crankshaft fixed sprocket 46, a camshaft fixed ring gear 51 and designed as a double eccentric shaft 50 adjusting shaft. This is connected via a detachable spline coupling 62 with the adjusting motor, not shown. The double eccentric gear 44 is braced by a central special clamping screw 54 with a camshaft pin 55 of a camshaft 69. Again, the angular position between the camshaft 69 and the Doppelexzentergetriebe 44 is determined by a fixing pin 60, which sits with an interference fit in aligned holes of the ring gear 51 and the camshaft pin 55. The central special clamping screw 54 can be tightened through the splined coupling 62.

A cylindrical screw head 53 of the special clamping screw 54 also serves as a bearing surface for the needle sleeve 57 of the double eccentric shaft 50, which thereby builds extremely short. In turn, it has two identical, offset by 180 ° eccentric 70, which drive via two roller bearings 56 two identical spur gears 49. The bearings 56 can also be replaced by plain bearings that save costs and space, but have higher friction. The spur gears 49 mesh with internal teeth 52 of the camshaft-fixed ring gear 51. At its periphery is a crankshaft fixed drive wheel 45th arranged, with a peripheral part 75 which is integrally formed with the sprocket 46 and a side part 76. The latter serves, inter alia, as a side termination of the double eccentric gear 44. The peripheral part 75 is mounted on the circumference of the ring gear 51 in a sliding bearing 58. The side part 76 has axial bores 77, in which axial pins 47 are pressed, which, as in FIG. 3 engage in bores 48 of the spur gears 49 and transmit the drive torque of the drive wheel 45 via the spur gears 49 on the ring gear 51 and the camshaft 69. The crankshaft fixed drive wheel 45 and with it the spur gears 49 and the double eccentric shaft 50 are axially fixed by a snap ring 59. This sits in a radial groove 71 of the crankshaft fixed drive wheel 45 and is located with a flank on a camshaft near end face 72 of the ring gear 51 at. The camshaft remote end face 73 of the ring gear 45 abuts with play on the axial inner side 74 of the drive wheel 45. This game allows the relative movement of ring gear 51, drive wheel 45, spur gears 49 and double eccentric shaft 50th

The lubrication of the Doppelexzentergetriebes 44 takes place as in the Doppelexzentergetriebe 19 through an inflow bore 61 to the needle sleeve 57 and from there by centrifugal force to the other components.

Ist in diesem Fall die Drehzahl der Doppelexzenterwelle, zum Beispiel durch Kurzschlussbremsen des Verstellmotors kleiner als die des Kettenrads 46, so dreht sich die Nockenwelle 69 langsamer als dieses und verstellt so nach "spät".The double eccentric gear 44 is also a plus gear. Since the number of teeth Z _{NW of} the camshaft-fixed ring gear 52 is greater than the number of teeth Z _KW each of the identical design spur gears 49, there is a stationary gear ratio: $${\mathrm{i}}_{\mathrm{0}}=\frac{{\mathit{Z}}_{\mathit{northwest}}}{{\mathit{Z}}_{\mathit{KW}}}>1.$$

In this case, the speed of the double eccentric shaft, for example by short-circuit brakes of the adjusting motor smaller than that of the sprocket 46, the cam shaft 69 rotates slower than this and adjusted so "late".

The double eccentric gear 19 serves as an adjusting mechanism of a Auslassnokkenwelle with base position "early", the other Doppelexzentergetriebe 44 as adjusting an intake camshaft with base position "late".

LIST OF REFERENCE NUMBERS

1

variator

2

adjusting

3

camshaft

4

driving part

5

stripping section

6

adjusting

7

drive wheel

8th

Permanent magnet rotor

9

stator

10

casing

11

phase

12

stator

13

control unit

14

Short-circuit line

15

control line

16

Short-circuit switch

17

power resistor

18

electronic current regulator

19

double eccentric

20

crankshaft fixed ring gear

21

Sprocket

22

internal gearing

23

drain hole

24

drain hole

25

Camshaft-resistant cover

26

pen

27

axial bore

28

spur gear

29

double eccentric

30

clamping sleeve

31

Standard clamping screw

32

needle sleeve

33

bearings

34

End cover

35

circlip

36

Standard screw head

37

Feather shaft coupling

38

camshaft journal

39

locating pin

40

inflow line

41

Oil drilling

42

outflow bore

43

bearings

44

another double eccentric transmission

45

crankshaft-proof drive wheel

46

Sprocket

47

axial pin

48

drilling

49

spur gear

50

double eccentric

51

Camshaft-fixed ring gear

52

internal gearing

53

cylindrical screw head

54

Special clamping screw

55

camshaft journal

56

roller bearing

57

needle sleeve

58

bearings

59

circlip

60

locating pin

61

supply bore

62

Spline coupling

63

axial bore

64

axis of rotation

65

camshaft

66

opening

67

eccentric

68

axial bore

69

camshaft

70

eccentric

71

radial groove

72

camshaft close end

73

Camshaft far front side

74

axial inside

75

peripheral part

76

side panel

77

axial bore

78

groove

79

inside

80

inside

Claims (15)

1. Electrical apparatus for adjusting the rotary angle position of the camshaft (3, 65, 69) in relation to the crankshaft of an internal combustion engine, having an adjusting gear mechanism (1) which is in the form of a triple shaft gear mechanism and has a drive part (4) which is fixed to the crankshaft, an output drive part (5) which is fixed to the camshaft, and an adjusting shaft (6) which is connected in a rotationally fixed manner to an electric adjusting motor (2) which has a permanent-magnet rotor (8) and a stator (9) which is fixed to the housing, with a stationary gear mechanism transmission ratio $i_o=\frac{{\mathit{number\; of\; output\; drive\; teeth\; Z}}_{\mathit{NW}}}{{\mathit{number\; of\; drive\; teeth\; Z}}_{\mathit{KW}}},$

   

   , the value of which determines the class of the adjusting gear mechanism (1) as a positive or negative gear mechanism and the adjusting direction of the camshaft (3, 65, 69) in an early or late basic position, existing between the drive part (4) and the output drive part (5) when the adjusting shaft (6) is stationary, characterized in that, by virtue of suitable structural design of the adjusting gear mechanism (1), stationary gear mechanism transmission ratios i₀ can be realized, by means of which an early or a late basic position of the camshaft (3, 65, 69) can be reached solely by braking the adjusting shaft (6) when the adjusting gear mechanism (1) is rotating, and in that the adjusting shaft (6) is preferably braked by short-circuit braking of the adjusting motor (2).
2. Adjusting apparatus according to Claim 1, characterized in that a stationary gear mechanism transmission ratio 0 < i₀ < 1 can be used to realize a positive gear mechanism for camshaft adjustment in the direction "early" and a stationary gear mechanism transmission ratio i₀ > 1 can be used to realize a positive gear mechanism for camshaft adjustment in the direction "late".
3. Adjusting apparatus according to Claim 2, characterized in that the adjusting gear mechanism (1) provided is a double eccentric gear mechanism (19) or a wobble gear mechanism and another double eccentric gear mechanism (44).
4. Adjusting apparatus according to Claim 3, characterized in that the double eccentric gear mechanism (19) has a cover (25) which is fixed to the camshaft and is firmly connected to axial pins (26) which engage in holes (27) in two spur gears (28) of identical design with linear contact, and in that the spur gears (28), which can be driven by the adjusting motor (2) via a double eccentric shaft (29), mesh with a ring gear (20) which is fixed to the crankshaft.
5. Adjusting apparatus according to Claim 4, characterized in that the double eccentric shaft (29) is roll-mounted on a screw sleeve (30) of a central standard clamping screw (31) with a needle sleeve (32), and the spur gears (28) of structurally identical design are mounted on the double eccentric shaft (29) in sliding bearings (33).
6. Adjusting apparatus according to Claim 5, characterized in that the number of teeth Z_NW of each of the two spur gears (28) of structurally identical design (equal to the number of output drive teeth) is lower than the number of teeth Z_KW of the ring gear (20) which is fixed to the crankshaft (equal to the number of drive teeth), and this leads to a stationary gear mechanism transmission ratio of 0 < i₀ < 1.
7. Adjusting apparatus according to Claim 3, characterized in that another double eccentric gear mechanism (44) has a drive gear (45) which is fixed to the crankshaft and is firmly connected to axial pins (47) which engage in holes (48) in two spur gears (49) of structurally identical design with linear contact, and in that the spur gears (49) of structurally identical design, which can be driven by the adjusting motor (2) via a double eccentric shaft (50), mesh with a ring gear (51) which is fixed to the camshaft.
8. Adjusting apparatus according to Claim 7, characterized in that the double eccentric shaft (50) is mounted on a cylindrical screw head (53) of a central special clamping screw (54) and the spur gears (49) of structurally identical design are mounted on the double eccentric shaft (50), preferably in rolling bearings (56).
9. Adjusting apparatus according to Claim 8, characterized in that the number of output drive teeth Z_NW of the ring gear (51) which is fixed to the camshaft is greater than the number of drive teeth Z_KW of each of the spur gears (49) of structurally identical design, and this leads to a stationary gear mechanism transmission ratio of i₀ > 1.
10. Adjusting apparatus according to Claim 1, characterized in that the stator (9) of the adjusting motor (2) preferably has three phases (10) which can be short-circuited individually and as a whole for the purpose of short-circuit braking of the adjusting motor (2).
11. Adjusting apparatus according to Claim 10, characterized in that short-circuit switches (15) are provided which are closed when no power is supplied to the adjusting motor (2) and are open when power is supplied to the adjusting motor (2).
12. Adjusting apparatus according to Claim 11, characterized in that measures are provided for limiting the short-circuit current.
13. Adjusting apparatus according to Claim 12, characterized in that the short-circuit switches (15) open, preferably with the aid of the short-circuit current, when a limit value of the short-circuit current is exceeded, and automatically close when said limit value is undershot.
14. Adjusting apparatus according to Claim 12, characterized in that a line resistor (16) is arranged in the short-circuit lines (13).
15. Adjusting apparatus according to Claim 12, characterized in that an electronic current controller (17) which is operated by short-circuit current is provided in the short-circuit lines (13).

Images