EP1047874B1 - Electric motor with drive - Google Patents

Description

The present invention relates to an electrical machine used as a starter and generator for an internal combustion engine, in particular an internal combustion engine of a motor vehicle is switchable. Such machines are has been developed as it enables the two functions of tempering the internal combustion engine and the generation of electric current, which is used for the vehicle's on-board systems, such as ignition, lighting etc. will unite in a single electrical machine and so weight and save costs.

With such electrical machines, however, the problem arises that for generator operation and for starter operation of the electrical machine different gear ratios are needed so that a switchable gear must be provided that this different Translations depending on the function of the electrical machine currently required allowed to produce.

An electrical machine with the features of the preamble of the claim 1 is known from DE-A-2504867. The well-known electrical machine serves not only as a starter for the internal combustion engine and as a generator for the power supply of the motor vehicle, but serves in engine operation at the same time as a second drive unit for the motor vehicle. The machine has one connected to the ring gear of a stage of the planetary gear Output shaft on while the output shaft of the internal combustion engine is connected to the central or sun gear of the other stage. As the relatively large construction volume and that due to the additional functions are not optimal for use as a starter on the one hand and generator, on the other hand, adjusted gear ratios.

Advantages of the invention

By the present invention, as defined in claim 1, an electrical Machine for use as a starter or generator for an internal combustion engine created a simple switch between at the Operation of the electrical machine as a starter or as a generator optimally adapted Translation ratios allowed with simple means.

Desirable gear ratios are, for example, when used a claw pole machine (synchronous or asynchronous machine) as electrical Machine a gear ratio range from 1.6 to 4 for generator operation or from 4 to 60 in starter mode. The spread, i.e. the ratio of the gear ratios to one another must be at least 2.

The braking force can in particular be attacked by the braking devices exercised on a ring gear of the planetary gear in a simple manner be, as braking devices in particular shoe brakes, multi-disc brakes or friction band brakes.

By braking one of the two ring gears, a rotational force between each the sun gear of the braked stage of the two-stage gearbox and transmitted to the planet carrier while the other stage is free rotates.

The construction according to the invention also enables a particularly compact design, in which the dimensions of the two ring gears are identical are. This reduces the number of different components required of the transmission and enables more rational and cost-effective production.

To simplify the control of the planetary gear is preferred a common actuator to operate both brake devices provided the at least one working position, in the first brake device open and the second is closed, a working position in which the second brake device open and the first closed and has an idle position, in which both are open. These positions are by one that is movable with one degree of freedom Control adjustable. This degree of freedom is preferably a rotation so that the actuator for example with the help of any common Electric motors is easy to operate.

A smooth transition between the two translation states of the transmission, each one Correspond to the working position of the adjusting device, to ensure the actuator is preferred about the idle position from a working position movable into the other.

It is also appropriate that the actuator beyond a working position into a braking position is movable in the in the working position open braking device is braked. there is a state of the braking device under "braked" understood in which the braking torque of Zero different, but is so limited that overload of the transmission and the drive train is excluded. The whole Closing a braking device should be the actuator only allow if not at the same time the other braking device is also closed is.

In a first preferred embodiment of the Actuator in which the braking devices due to actuating movements parallel to an axis of the transmission are actuated, includes the actuator two ramps rotatable about this axis Converting a rotary movement into an actuating movement the braking devices. To operate the braking devices to couple, it is enough if the two Ramps are non-rotatably connected. Such an actuator is especially for use with multi-disc brakes suitable as braking devices.

In a second embodiment of the steep device, in which the braking devices through a a vertical movement of an axis of the gear can be actuated, the adjusting device has at least a cam and with the cam interactive levers for implementing a rotation the cam disc in an actuating movement of the braking devices on. Of course you can too each lever and thus each braking device own cam disc must be assigned. This configuration is particularly related to use with shoe brakes suitable as braking devices.

Further features and advantages of the invention result itself from the following description of exemplary embodiments.

characters

Figuren 1, 2, 2a und 3 Schemata von Ausgestaltungen von Planetengetrieben der erfindungsgemäßen Maschine,

Figur 4 einen Längsschnitt durch ein Getriebe gemäß der ersten Ausgestaltung; und

Figur 5 einen Schnitt entlang der Linie V-V in Figur 4.

Figur 6 einen axialen Schnitt durch ein Getriebe der erfindungsgemäßen Maschine mit zwei Lamellenbremsen und einer gemeinsamen Stellvorrichtung für die zwei Lamellenbremsen;

Figur 7 eine perspektivische Ansicht eines Stellrings der Stellvorrichtung aus Figur 6, der zwei Rampen zum Einstellen einer Lamellenbremse in unterschiedliche Betriebspositionen aufweist;

Figur 8 eine graphische Darstellung der axialen Verlagerung der Lamellenbremsen in Abhängigkeit von der Orientierung des Stellrings;

Figuren 9 und 10 jeweils Ansichten einer Stellvorrichtung zum gemeinsamen Stellen von zwei Lamellenbremsen;

Figur 11 eine perspektivische Ansicht einer Backenbremse;

Figur 12 eine schematische Darstellung des Zusammenwirkens der Backenbremse mit einem Steuerelement;

Figur 13 eine Seitenansicht eines Getriebes, das mit zwei Backenbremsen gemäß Figur 11 und einer Stellvorrichtung gemäß Figur 12 ausgestattet ist; und

Figur 14 eine schematische Darstellung der Anordnung der erfindungsgemäßen Maschine im Antriebsstrang eines Kraftfahrzeugs.

Show it:

1, 2, 2a and 3 show schemes of configurations of planetary gears of the machine according to the invention,

Figure 4 shows a longitudinal section through a transmission according to the first embodiment; and

FIG. 5 shows a section along the line VV in FIG. 4.

Figure 6 shows an axial section through a transmission of the machine according to the invention with two multi-disc brakes and a common adjusting device for the two multi-disc brakes;

FIG. 7 shows a perspective view of an adjusting ring of the adjusting device from FIG. 6, which has two ramps for setting a multi-disc brake in different operating positions;

FIG. 8 shows a graphical representation of the axial displacement of the multi-disc brakes as a function of the orientation of the adjusting ring;

FIGS. 9 and 10 each show views of an adjusting device for jointly setting two multi-disc brakes;

Figure 11 is a perspective view of a shoe brake;

FIG. 12 shows a schematic illustration of the interaction of the shoe brake with a control element;

FIG. 13 shows a side view of a transmission which is equipped with two shoe brakes according to FIG. 11 and an adjusting device according to FIG. 12; and

Figure 14 is a schematic representation of the arrangement of the machine according to the invention in the drive train of a motor vehicle.

Description of the embodiments

For an overview, the arrangement of an electrical machine according to the invention in the drive train of a motor vehicle is briefly illustrated with reference to FIG. 14. This drive train comprises an internal combustion engine 30 which can be connected via a main clutch 31 to a manual transmission 32 which drives various wheels of the motor vehicle with various adjustable transmission ratios via an output shaft 37. An internal combustion engine shaft 4 passes through the manual transmission 32 and is connected to the transmission 33 of the electrical machine according to the invention. The gear 33 has two stages, each gear stage 34 _i , 34 _ii is assigned its own braking device 35 _i , 35 _ii . With the aid of the braking devices, the transmission ratio between the shaft 4 and a shaft 6, which is connected to an electrical machine 36, can be adjusted. One of the two transmission ratios of the transmission 33 is provided for the operation of the electrical machine 36 as a starter of the internal combustion engine 30 and the other for the operation as an alternator.

Different configurations of gears 33 now treated with the aid of FIGS. 1, 2, 2 A and 3.

First, the one used here with reference to FIG highly schematic representation in general are explained. Figures 1 to 3 show highly schematic axial cuts through gears. Short horizontal lines 10 represent each the toothing of a gear. Two each such lines are indicated by a vertical line 11 connected, which symbolizes the disc of the gear. An open circle 12 in the middle of the line 11 indicates that the gear in question by one Axis through a horizontal, through the circle 12 running line is symbolized, freely rotatable is. A closed round point 13 represents one firm connection between the gear in question and its axis.

In the transmission shown in FIG. 1, the internal combustion engine is coupled via a shaft 4 to a planet carrier 5, which rotatably holds planet wheels 2 ₁ , 2 _{2 of} the two stages of the planetary gear. These planet gears each mesh with a sun gear 1 _i or 1 _ii and a ring gear 3 _i or 3 _ii . The sun gears are fixedly mounted on a shaft 6 coupled to the electrical machine (not shown). In order to set a transmission ratio, a braking device (not shown in FIG. 1) engages on an outer surface 8 _i , 8 _{ii of} one of the ring gears 3 _i , 3 _ii and prevents it from rotating while the other ring gear is freely movable. In this way, a driving force is transmitted from the shaft 4 to the shaft 6 or in the opposite direction, depending on whether the electrical machine works as a starter or as a generator, through that of the two gear stages, the ring gear of which has just been braked. The planet and ring gears of the other stage run freely. The direction of movement of the free-running ring gear differs depending on the gear ratio set, but the path speed of the ring gear is in any case relatively low compared to that of a blocked ring gear in a single-stage planetary gear. Therefore, the mass moment of inertia of the two-stage planetary gearbox is surprisingly low despite the increased number of components compared to a single-stage gearbox and allows fast and low-wear switching between different gear ratios.

FIG. 4 shows the structure of the two-stage planetary gear from FIG. 1 in a detailed axial section. The shaft 4 connected to the internal combustion engine carries a planet carrier 20 in the form of a plate-like flange, on the outer edge of which three pins 21 _i (see also FIG. 5) are let in at an angular distance of 120 °, which are the axes of rotation of the planet wheels 2 _{i of} the first gear stage define. The disks 22 _{i of} the planet gears 2 _i have only a fraction of the axial dimension of the teeth and are also broken through in order to keep the moment of inertia of the wheels as low as possible. The ring gear 3 _i is screwed to a flange 23 which has a cylindrical projection 24 as an engagement surface for a braking device.

In each case diametrically opposite to a pin 21 _i , the planet carrier 20 has an arm 27 projecting over the axial width of the first gear stage, at the end of which a further pin 21 _{ii is} anchored, each of which carries a planet gear 2 _{ii of the} second gear stage. A flange 25 fixedly connected to the ring gear 3 _ii forms a carrier for plates 26 of a plate brake.

FIG. 5 shows a simplified cross section along the line VV from FIG. 4. The gear wheels 1 _i , 2 _i , 3 _{i of} the first stage are shown in section, the sun gear 1 _ii is partially covered. The arms 27 of the planet carrier 20, which hold the planet gears 2 _{ii of} the second stage, extend through spaces which exist between the planet gears 2, the first stage. The ring gear 3 _{ii of} the second stage is identical in size to the ring gear 3 _{i of} the first. The suns are denoted by 1 _i and 1 _{ii in} FIG.

wenn das Hohlrad 3_i in den Stand abgebremst ist
(n_3i=0), und

bei stehendem Hohlrad 3_ii (n_3ii=0) , wobei U das Übersetzungsverhältnis und Z die Zahl der Zähne eines Zahnrads bezeichnet.The gear ratios of the gearbox are given by the formulas

when the ring gear 3 _i is braked to a standstill
(n _3i = 0), and

with stationary ring gear 3 _ii (n _3ii = 0), where U denotes the gear ratio and Z the number of teeth of a gear.

As can be seen from the following Table 1, with moderate tooth numbers of not more than 75 for the ring gears, gear ratios U _ii of approx. 2.5 for the second stage and U _i of over 5 for the first, as well as spreadings U = U _i / U _ii reachable from up to 3 and more. Smaller ratios can also be achieved with this design, but large diameters of the ring gear and sun gear are required for this, which runs counter to the desire for a compact design. Z _1ii Z _2ii Z _3ii Z _1i Z _2i Z _3i U _ii U _i Φ 45 11 67 11 28 67 2.48 7.09 2.70 47 11 69 11 29 69 2.46 7.27 2.94 47 11 69 13 28 69 2.46 6.80 2.55 47 11 69 15 27 69 2.46 5.60 2.26 47 11 69 17 26 69 2.46 5.05 2.04 47 13 73 11 31 73 2.55 7.63 2.99 47 13 73 13 30 73 2.55 6.61 2.59 47 13 73 15 29 73 2.55 5.86 2.29 49 11 71 11 30 71 2.44 4.45 3.04 49 11 71 13 29 71 2.44 6.46 2.63 49 11 71 15 28 71 2.44 5.78 2.34 49 13 5 13 31 75 2.53 5.76 2.67 49 13 75 15 30 75 2.53 6.00 2.37 49 13 75 17 29 75 2.53 5.41 2.13 51 11 73 11 31 73 2.43 7.68 3.14 51 11 73 13 30 73 2.43 6.64 2.72 51 11 73 15 29 73 2.43 6.86 2.41 51 11 73 17 28 73 2.43 5.29 2.17 51 11 73 19 27 73 2.43 4.84 1.99 51 13 77 13 32 77 2.50 6.92 2.75 51 13 77 15 31 77 2.50 6.18 2.44 51 13 77 17 30 77 2.50 5.52 2.20 51 13 77 19 29 77 2.50 5.05 2.01 53 11 75 11 32 75 2.41 7.81 3.23 53 11 75 13 31 75 2.41 6.76 2.80 53 11 75 15 30 75 2.41 6.00 2.48 53 11 75 17 29 75 2.44 5.41 2.24 43 10 63 11 26 63 2.46 6.72 2.72 45 10 65 11 27 65 2.44 6.90 2.82 49 10 69 11 29 69 2.40 7.27 3.02 51 10 71 11 30 71 2.39 7.46 3.11

Figure 2 shows the diagram of a second embodiment of a two-stage planetary gear for an electrical machine according to the invention. In this construction, the shafts 4 and 6 connected to the internal combustion engine and the electrical machine are each firmly connected to a sun gear 1 _i and 1 _ii . Planet gears 2 _i and 2 _{ii of} the two stages are firmly coupled to one another by a common axis 7. In this construction, basically three different transmission ratios can be set, two of them by locking a ring gear each and the third by locking the planetary movement, that is to say holding the axes 7 of the pairs of planet gears.

U 3 = Z 1i Z 2ii Z 1ii Z2i ,ns = 0 wobei die Angabe n_3ii=0 beziehungsweise n_3i=0 bedeutet, daß das Hohlrad 3_ii beziehungsweise 3_i arretiert ist und n_s=0 bedeutet, daß die Planetenbewegung arretiert ist.The gear ratios are given by the formulas

U 3 = Z 1 i Z 2 ii Z 1 ii Z 2 i . n s = 0 where the specification n _3ii = 0 or n _3i = 0 means that the ring gear 3 _ii or 3 _{i is} locked and n _s = 0 means that the planetary movement is locked.

Exemplary results for gear ratios U ₁ , U ₂ , U ₃ and spreads Φ for the various combinations of tooth numbers Z of the individual gears are listed in Table 2 below. Z _1i Z _2i Z _3i Z _1ii Z _2ii Z _3ii U ₁
n _3ii = 0 U ₂
n _3i = 0 U ₃
n _s = 0 Φ = U _{2 /} U ₁ Φ = U ₃ / U ₁ 53 11 75 29 35 99 2.78 3.82 5.81 1.37 2.09 55 10 75 36 29 94 2.27 2.97 4.43 1.31 1.95 53 9 71 33 29 91 2.45 3.39 5.17 1.38 2.11 53 10 73 33 30 93 2.40 3.21 4.81 1.33 2.00 53 11 75 33 31 95 2.37 3.06 4.52 1.29 1.90 53 9 71 35 27 89 2.27 3.02 4.54 1.33 2.00 53 12 77 31 34 99 2.52 3.27 4.84 1.29 1.91 53 12 77 33 32 97 2.33 2.94 4.28 1.26 1.83 55 11 77 33 33 99 2.50 3.33 5.00 1.33 2.00 55 10 75 35 30 95 2.35 3.14 4.71 1.33 2.00 55 9 73 35 29 93 2.39 3.31 5.06 1.38 2.11 55 10 75 36 29 94 2.27 2.97 4.43 1.31 1.95 57 10 77 37 30 97 2.31 3.08 4.62 1.33 2.00 57 11 79 37 31 99 2.27 2.94 4.34 1.29 1.90 59 10 79 39 30 99 2.26 3.02 4.53 1.33 2.00 49 10 69 35 24 83 1.97 2.38 3.36 1.20 1.70 49 10 69 33 26 85 2.14 2.67 3.86 1.24 1.80 49 10 69 31 28 87 2.32 3.00 4.42 1.28 1.90 49 10 69 29 30 89 2.53 3.37 5.06 1.33 2.00 49 10 69 30 29 88 2.42 3.18 4.73 1.31 1.95

It can be seen that in each case the smallest transmission ratios U _{1 are} achieved by holding the ring gear 3 _{ii of} the second stage because in this stage the diameter of the planet gears 2 _{ii is} larger than that of the planet gears 2 _{i of} the first stage. The greatest transmission ratio is achieved by holding the axles 7 in place. With this transmission, the ring gear of the first stage can therefore be dispensed with, unless this is necessary for the mechanical stability of the transmission.

To lock the movement of the axes 7 around the Shafts 4 and 6 can be a braking device used on the ends of the axes 7 exerts a force in the axial direction as by the arrows 9 indicated in Figure 2, and the axes like a planetary movement, but not the planet gears prevents rotation about the axes.

A modification is shown in FIG. 2a. A planet carrier 20 'extends here between the two gear stages, and the axes 7 are held in bores of the planet carrier 20'. A braking force F acts on a cylindrical outer surface 8, which surrounds the edge of the planet carrier 20 ', in the same way as on the ring gears of the configurations described with reference to FIGS. 1, 4 and 5 or 2. In this construction, braking devices of the same type can be used to brake the movement of the axles 7 as well as the rotation of the ring gear 3 _ii , which simplifies the construction.

3, the shaft 4 of the internal combustion engine is firmly connected to a large sun gear 1 _i which meshes with the planet gears 2 _i . These are rotatably mounted on a planet carrier 20 ″ and mesh with planet gears 2 _{ii of} the second stage, which are mounted on the same carrier 20 ″. The latter are in engagement with a small sun gear 1 _ii , which is coupled via a shaft 6 to an electrical machine provided as a starter or generator of the motor vehicle. The gearbox has two gear ratios. In the first, the ring gear 3 _{ii of} the second stage is fixed, in the second it is the planet carrier 20 ″. No ring gear is required in the first stage, which has a clear advantage in terms of compactness and moment of inertia, since this ring gear, if it were present, would have to be significantly larger and heavier than that of the second stage.

The planet carrier 20 ″ holds the planetary gears 2 _{ii of} the second stage with the aid of arms that are partially cranked outside the sectional plane of the figure in the direction of the planetary movement, which is indicated in the figure by a broken line.

The planet carrier 20 '' is like the planet carrier 20 'of Figure 2A by a cylindrical Lockable outer surface 8 engaging brake.

The following table shows gear ratios U ₁ , U _{2 of} the two gear ratios for different numbers of teeth Z of the different wheels. Z _1i 2 _2i Z _1ii Z _2ii Z _3ii U ₁
n _s = 0 U ₂
n _3ii = 0 Φ = U ₁ / U ₂ 27 55 11 13 37 2.45 1.11 2.20 33 47 11 11 33 3.00 1.29 2.31 37 43 13 13 39 2.84 1.39 2.03 51 19 10 11 32 5.10 2.35 2.16 49 47 11 19 49 4.45 2.12 2.10 57 47 11 23 57 5.18 2.55 2.02 61 71 11 25 61 5.54 2.37 2.33 37 43 13 14 41 2.84 1.43 1.98 56 17 12 11 34 4.66 2.23 2.08 37 53 11 13 37 3.36 1.41 2.37 49 53 11 19 49 4.45 2.02 2.20 41 43 13 14 41 3.15 1.53 2.05 37 43 13 13 39 2.85 1.40 2.04 37 39 13 13 39 2.84 1.45 1.96 37 41 11 13 37 3.36 1.58 2.12 29 43 11 11 33 2.63 1.23 2.13

Translation ratios can also be found here suitable range and spreads of 2 or clear above with moderate number of teeth and consequently with an overall compact gearbox.

FIG. 6 shows in axial section a gear 33 with two multi-disc brakes 35 _i , 35 _ii and an actuating device for actuating the two multi-disc brakes together. The structure of the transmission corresponds to that of Figure 1 and will not be described again in detail. The disk brakes 35 _i , 35 _ii each comprise a disk set connected to a ring gear 3 _i , 3 _ii and a _{disk set} connected to an axially displaceable carrier 40. The displaceable plate set is pressed by a spring (not shown) against an adjusting ring 41, which FIG. 7 shows in a perspective view. Due to the force of the spring, the adjusting ring 41 is clamped axially between the lamellae and a set of stationary rollers 42.

As can be seen in FIG. 7, the adjusting ring 41 bears two circumferentially extending ramps 43, on the surface of which a roller 42 runs when the adjusting ring 41 around the shaft 4 or 6 is rotated. Depending on the height of the ramps 43 to the Places where they contact the rollers 42 are, the disk carrier 40 are different shifted far axially, that means the brake is different strongly attracted.

The two adjusting rings 41 are connected via a bridge 44 a telescopic mechanism rotatably but axially against each other slidably connected. One of Collars 41 carries one on its outer circumference Sprocket, which meshes with a pinion 45, which by a motor 46 via a reduction gear 47 is driven. The ring gear extends over an angular segment whose size is at least that of each ramp corresponds to 43 spanned angle.

Figure 9 shows a perspective view of the Adjusting device from Figure 6 and the geared motor arrangement 46.47. The ring gear has the shape of a on a collar 41 fixed segment 48, from which the bridge 44 to the second Collet 41 goes out. The bridge 44 consists of two interlocking, axially rail-guided Elements.

The components 41 to 45 and 48 can be regarded as a single adjusting device which, by simply rotating the pinion 45, allows the braking devices 35 _i , 35 _ii to be brought into different positions when coupled.

Which positions each of the braking devices Taking together depends on the shape of the ramps 43 from.

FIG. 8 shows an example of a possible height profile of the ramps 43 of the two adjusting rings 41 from FIG. 6 along their circumference. The lower curve corresponds to the collar shown in FIG. 7. Corresponding positions of the adjusting ring 41 in FIGS. 7 and 8 are each identified by letters a to e. The circles on the curves in positions a to e each symbolize the roller 42 assigned to the ramp in different positions of its path. In a first position a, the ramp from FIG. 7 has a height h _a (see lower curve in FIG. 8), in which the assigned braking device brakes but does not block completely. In positions b and c and the area in between, the braking device is open, between d and e the braking force increases until at d the brake is closed, between e and d the height of the ramp is constant. The course of the ramp assigned to the other braking device, which is shown in the upper curve in FIG. 8, is mirror-symmetrical to this. In position c both brake devices are thus open, the transmission 33 is in an idle state. By turning in the direction of position d, one braking device is gradually closed while the other remains open. This state is a working state of the transmission with one of the two possible gear ratios. The second gear ratio is set by turning it in the opposite direction to position b. Rotations beyond the positions b, d also lead to states in which one braking device is closed and the other brakes the entire drive train of the vehicle with a limited braking force.

Figure 10 shows schematically a variant of a Setting device. Here are the collars 41 both serrated on at least part of its outer circumference and comb with pinions 45 which, on a common Shaft 49 mounted, driven by motor 46 become. The width of the pinion is respectively the teeth of the adjusting wheels 42 so dimensioned that the adjusting wheels due to the interaction the (not shown in this figure) Axially move ramps with the braking devices can, without doing with the pinions 45 except Intervention to come.

Other variants affect the number of ramps a collar that is easily larger than 2 can be. It is also easily possible that Ramps on the side facing the disk carrier the collars and so the ramps directly to interact with the slat carriers, instead of using the stationary rollers 42 the entire collar 41st to move axially.

A second embodiment of a braking device, in the form of a shoe brake is shown in Figure 11. This designated with the reference numeral 50 Shoe brake includes two arms 51 which are around in relation to the fixed transmission 33 (not shown here) Axes 52 are pivotable. Each arm 51 carries a brake shoe 53. A tension spring 49 exercises on the Arms 51 exert a force on opening the Brake works.

The arms 51 carry opposite ends at their ends, pointed triangular noses 54. An adjusting lever 55 is about a stationary axis 58 pivotable and carries one on a first arm 57 Rider 59 with a recess into which the lugs 54 intervention. The rider 59 is pivoted of the lever 55 perpendicular to the axis of the Gear can be moved in the direction of arrow A. The second arm 56 of the actuating lever 55 acts as in FIG 12, together with a cam disk 60 and thus determines the height of the rider 59 on the noses 54. To make the profile of the cam disc more recognizable to make is around their center of rotation dash-dotted circle, its radius is equal to the maximum radius of the cam disc. The further down the rider 59 in FIG. 11 is pressed, the more the brake shoes press 53 against the (not shown) between them arranged ring gear of the transmission. The cam disc 60 (like the collar of the previously described Configurations) take positions that in Figure 12 are designated by letters a to e and in the same way as those described above States open, closed or slowed down States of the shoe brake 50 correspond.

FIG. 13 shows a side view of a transmission 33 with two shoe brakes 50 _i , 50 _ii with the construction described above, which are each assigned to the two stages 34 _i , 35 _{ii of} the transmission. Two cam disks 60 _i , 60 _ii are connected to a servomotor 46 via a common shaft 49. The two cam disks are identically shaped, but are arranged in mirror image to one another, so that in the position shown in FIG. 13 a second lever 56 _{i is} lowered, the associated shoe brake 50 _{I is} thus open and the other second lever arm 56 _{II is} raised, the shoe brake 50 _ii is closed accordingly.

In this embodiment, each control lever is assigned its own cam disk 60 _I , 60 _II . Alternatively, it would also be possible to have the two actuating levers engage on a common cam disk with an offset angle.

Claims (16)

1. Electrical machine, which can be connected as a starter and a generator for an internal combustion engine, in particular a motor vehicle, and has a two-stage epicyclic gearbox for coupling to a shaft of the internal combustion engine, with each stage having a braking device for fixing a rotary movement of that stage, characterized in that the two-stage epicyclic gearbox comprises two sun wheels (1_i, 1_ii) which are firmly connected to a starter or generator shaft (6), and two sets of planet wheels (2_i, 2_ii), which engage with in each case one of the sun wheels and a hollow wheel (3_i, 3_ii), with the planet wheels (2_i, 2_ii) in the two sets being mounted such that they can rotate on a planet support (20) which is firmly coupled to the internal combustion engine shaft (4).
2. Electrical machine according to Claim 1, characterized in that the dimensions of the two hollow wheels (3_i, 3_ii) are identical.
3. Electrical machine according to Claim 1 or 2, characterized in that the step-up ratios of the two stages are between 2.4 and 7.5, and have a spread of between 2 and 3.
4. Electrical machine according to one of the preceding claims, characterized in that the rotation speed of the internal combustion engine shaft (4) is essentially equal to the rotation speed of the internal combustion engine.
5. Electrical machine according to one of the preceding claims, characterized in that the two braking devices act on the hollow wheels (3_i, 3_ii) of the epicyclic gearbox.
6. Electrical machine according to one of the preceding claims, characterized in that the braking devices are drum brakes, disc brakes or friction belt brakes.
7. Electrical machine according to one of the preceding claims, characterized in that the braking devices (35_i, 35_ii, 50_i, 50_ii) can be operated by a common actuating apparatus (41, 42, 43, 44, 45, 48; 49, 60_i, 60_ii, 56_i, 56_ii), which can assume at least an operating position (b), in which the first braking device is open and the second is closed, an operating position (d) in which the second braking device is open and the first is closed, and a freewheeling position (c) in which both are open, and can be set to the positions by means of a control element (45; 49) which can be moved with one degree of freedom.
8. Electrical machine according to Claim 7, characterized in that the actuating apparatus can be moved via the freewheeling position (c) from one operating position (b, d) to the other.
9. Electrical machine according to Claim 7 or 8, characterized in that the actuating apparatus can be moved beyond one operating position (b, d) to a braking position (a, e) in which the braking device which is open in the operating position (b, d) is braked.
10. Electrical machine according to one of Claims 7 to 9, characterized in that the actuating apparatus allows the closing of a braking device (35_i, 35_ii, 50_i, 50_ii) only when the other braking device is not closed at the same time.
11. Electrical machine according to one of Claims 7 to 10, characterized in that the braking devices (35_i, 35_ii) can be operated by means of actuating movements parallel to one axis (4, 6) of the gearbox, and in that the actuating apparatus (41, ..., 45, 48) has two ramps (43), which can rotate about the axis, in order to convert a rotary movement to an actuating movement of the two braking devices (35_i, 35_ii).
12. Electrical machine according to Claim 11, characterized in that the ramps (43) of the two braking devices (35_i, 35_ii) are connected such that they rotate together.
13. Electrical machine according to Claim 11 or 12, characterized in that the braking devices (35_i, 35_ii) are each arranged along the axis (4, 6), between the epicyclic gearbox (33) and the associated ramp (43).
14. Electrical machine according to one of Claims 11 to 13, characterized in that the braking devices (35_i, 35_ii) are disc brakes.
15. Electrical machine according to one of Claims 7 to 10, characterized in that the braking devices (50_i, 50_ii) can be operated by means of an actuating movement at right angles to one axis of the gearbox, and in that the actuating apparatus (49, 60_i, 60_ii, 50, 59) has at least one cam disc (60) and a lever (55), which interacts with the cam disc (60), in order to convert rotation of the cam disc (60) to an actuating movement of the braking devices (50_i, 50_ii).
16. Electrical machine according to Claim 15, characterized in that the braking devices (50_i, 50_ii) are drum brakes.

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