DE102008058275A1 - Pinion-differential gear unit for active control of torque distribution on wheels of motor vehicle, has actuation section cooperating with friction coupling, and helical gearings selected such that actuation of coupling is supported - Google Patents

Abstract

The gear unit (10) has a controllable friction coupling (30) comprising a primary part that is in drive-effective connection with an input element (14) i.e. crown wheel. The friction coupling has a secondary part in drive-effective connection with right and left output shafts (16, 16'). Helical gearings (42s, 44s) are gripped into each other. An axial component is axially shifted relative to the output shafts. The axial component has an actuation section (48) cooperating with the friction coupling. The helical gearings are selected such that an actuation of the coupling is supported.

Description

The The invention relates to a differential gear unit for active Control of a torque distribution.

A ordinary Differential gear unit is used to compensate for speed differences between two output shafts, the distribution of torques while of the operation can not be influenced. A differential gear unit with Lock function allows it, one of the output shafts with the input member of the differential gear unit or to directly couple with the other of the output shafts, for example in predetermined driving conditions a motor vehicle to the otherwise desired speed compensation prevent.

A Differential gear unit with active control of a torque distribution allows on the contrary a targeted influence on the distribution of the torque, for example, to wheels a motor vehicle is delivered. Such differential gear units can both as axle differential, d. H. between the wheels of an axle, as well as Zwischenachsdifferential, d. H. between two driven Axes, to be used. In an application as an axle differential can for example, in a curve the faster rotating outside wheel of the motor vehicle an additional Drive torque supplied become. Through the active control of the torque distribution is thus deliberately intervened in the driving dynamics of the vehicle and this improves.

Differential gear units of the aforementioned type usually comprise a differential gear, comprising one input link and two output shafts, each one Output shaft is associated with a controllable friction clutch. By a selective actuation of the friction clutches can be the amount of the torque transmitted to the respective output shaft varies become. When the friction clutches are actuated, axial forces of up to 15 kN applied to clutch torques of up to 12,500 Nm to produce. This means that the actuators of the friction clutches must be designed accordingly to generate the said forces to be able to. conventional Actuator systems require a relatively large amount of space in the tightly dimensioned Space of the axle regions and load - depending on the design of the Actuator - that hydraulic and / or electrical wiring system of the vehicle in not irrelevant way.

It is therefore an object of the invention, a differential gear unit to create that is more compact and efficient than designed conventional Differential gear unit of the type mentioned, and the but at the same time a reliable and fast torque distribution allows.

The Task is a differential gear unit with the features of claim 1.

The Differential gear unit according to the invention for actively controlling a torque distribution, in particular in a motor vehicle, has a differential gear, a Input element and two output shafts includes. Every output shaft is assigned a controllable friction clutch, the one with the Input member drivingly connected primary and one with the associated Output shaft drive has effectively connected secondary part. At least one the drive-effective connections comprises a first clutch side Gearing and a second gearing that mesh. The first coupling side toothing and the second toothing are Helical gears. A respective first clutch side toothing having Component is re the corresponding output shaft axially displaceable, wherein the component an operating section has, which cooperates with the respective friction clutch. The helical gears are chosen that an actuation the respective friction clutch is supported.

at a helical toothing are the teeth of one Gear not arranged parallel to the axis of rotation, but run diagonally to. For two intermeshing gears with helical teeth arises during operation, an axial component of force that is often considered parasitic and must be axially supported by suitable elements.

at the differential gear unit according to the invention is due to the helical gears - the in one of said drive-effective connections are provided - resulting axial forces However, to assist in the operation of the Friction clutches used. A first clutch-side gearing exhibiting component is axially displaceable with respect to the corresponding output shaft arranged. The component has a Operating section on, which cooperates with the respective friction clutch to actuate this Support friction clutch. When operating the differential gear unit, the component due the axial force generated by the interaction of the helical gears shifted in the axial direction, said shift over the Actuation section on the Transfer friction clutch becomes. Said named component thus supports the actuation of the Friction clutch. Depending on the design of the helical gears is the effect the clutch reinforced or toned down.

advantageous embodiments The invention are in the subclaims, the description and indicated in the drawings.

According to one Further development of the differential gear unit has each of the friction clutches one Aktuierungskolben and a disk set, wherein the respective operating section of the component arranged on the same side of the respective disk pack is like the actuator piston. This construction is very compact and manufacturing technology easy to implement. In particular the operating section disposed between the Aktuierungskolben and the disk set of the friction clutch.

The respective disc pack can be connected to the axial piston and the actuating portion axially facing away from the opposite side be. In this embodiment For example, the actuation piston and the actuation section act in the same direction and press the disk set against an axially fixed element together, for example, with a housing the differential gear unit is in communication to a torque transfer from the primary part to the secondary part - or vice versa - to accomplish.

Farther a component having the second toothing can be mounted axially fixed be. The axial force generated by the interaction of the helical gears will be complete in this case in an axial displacement environment of the operating portion having Component implemented with the clutch-side first gearing.

According to one another embodiment the differential gear unit according to the invention are the helical gears formed such that upon active actuation of the respective friction clutch an axial movement of the first toothing component is effected, so that the actuation in the sense of impression the friction clutch is supported becomes. In other words, for example, a right-increasing and a left-rising helical gearing one of the drive-effective connections arranged such that an indenting the friction clutch is assisted in its operation, d. H. an actuation force of an actuator of the friction clutch is amplified by the axial force component. The self-reinforcing design the Reibungskupplaktaktuatorik allows smaller dimensions the same.

The Differential gear unit according to the invention has thus over a self-reinforcing design the friction clutch operation, so that the corresponding friction clutch actuators less powerful and so that it can be made smaller. In addition, you can at the same power consumption of the actuators greater axial forces the friction clutches exercised become. Another advantage arises from the fact that at a Reversal of the sense of rotation, d. H. for example, in a reverse drive of the vehicle, the system is less stressed. In a reverse drive is in the big one Majority of cases an active torque distribution is not desired, so that an automatic opening of the Couplings advantageous effect.

at an advantageous embodiment of the differential gear unit according to the invention each output shaft is a mowing shaft parallel to this associated, arranged at the corresponding friction clutch is. The respective friction clutch surrounds the countershaft and is disposed adjacent to the associated output shaft. At least one of the drive-effective connections is by a spur / spur gear pairing educated. In this variant of the differential gear unit is the coupling-side first toothing arranged on a first spur gear, the non-rotatable with the secondary part the respective friction clutch is connected. The second gearing is formed on a second spur gear, the rotationally fixed and axially fixed to the output shaft is connected.

alternative the respective friction clutch can be the associated output shaft surround. The axis of rotation of the friction clutch is then with respect to Rotary axis of the output shaft offset, wherein at least one the drive-effective connections formed by a ring gear / spur gear pairing is.

According to one Further development of this variant of the differential gear unit according to the invention has a surrounding the associated output shaft part of the friction clutch an oblique toothed ring gear, which toothed with a corresponding outside Spur gear meshes, which is rotatably connected to the associated output shaft. Especially forms the component having the coupling side first toothing the oblique toothed ring gear.

The Invention will be hereinafter purely by way of example with reference to advantageous Embodiments and described with reference to the drawings. Show it:

1 a first embodiment of the differential gear unit according to the invention, and

2 a second embodiment of the differential gear unit according to the invention.

1 shows a differential gear unit 10 that a differential gear 12 with an input member 14 and a right output shaft 16 and a left output shaft 16 ' includes. The differential gear unit 10 is used to actively control the distribution of torque through the input member 14 , For example, a ring gear, is supplied. The input member 14 is with a differential carrier 18 rotatably connected. In other words, the torque provided by an internal combustion engine (not shown) should be distributed as needed to individual wheels of the vehicle (not shown) connected to the output shafts 16 . 16 ' keep in touch.

Since the differential gear unit 10 is constructed substantially symmetrical, the structure and operation will hereinafter only with reference to the right output shaft 16 associated elements described.

The right output shaft 16 is with an associated output element of the differential gear 12 coupled, wherein it is the differential gear 12 for example, can be a conventional bevel gear differential. Furthermore, the differential gear unit 10 a right superposition shaft 20 on (a left superposition wave 20 ' is only slightly to the left of the differential gear 12 shown), which is designed as a hollow shaft and which its associated output shaft 16 Coaxially surrounds. The superposition wave 20 is rotatable with the differential carrier 18 connected and can also be integrally formed with this. Also short shaft extensions on the differential carrier 18 basically the function of the superposition wave 20 fulfill.

The output shaft 16 and the superposition wave 20 are with a right superposition gearbox 22 connected. In other words, the right wheel of the axle of the vehicle is its own superposition gear 22 assigned. The left superposition gearing essentially corresponds to the right superposition gearing 22 and is therefore in 2 not shown.

As already stated, the differential carrier goes 18 in the formed as a hollow shaft overlay shaft 20 above. The superposition wave 20 indicates at her the differential gear 12 opposite end a spur gear 24 on which with a gear 26 - Which is also designed as a spur gear - meshes. The gear 26 is non-rotatable with a clutch basket 28 a friction clutch 30 connected. The friction clutch 30 points with the clutch basket 28 non-rotatably and axially displaceably connected outer plates 32 as well as inner fins 34 on, the rotationally fixed and axially displaceable with a clutch hub 38 are coupled. The slats 32 . 34 together form a disc pack.

The clutch hub 38 includes a hollow shaft portion which is a countershaft 40 Coaxially surrounds. The clutch hub 38 may be in the axial direction opposite the countershaft 40 move and is not rotatably coupled with this. Furthermore, the clutch hub 38 rotatably with a gear designed as a spur gear 42 connected, which with a rotationally fixed and axially fixed to the output shaft 16 coupled spur gear 44 combs.

The countershaft 40 serves in the illustrated embodiment, the differential gear unit 10 thus primarily the storage of the clutch basket 28 and the clutch hub 38 the friction clutch 30 and their respective associated gears 26 respectively. 42 , The countershaft 40 For example, in a housing of the differential gear unit 10 be stored in what 1 not shown in detail.

The gear 42 and the spur gear 44 each have a helical toothing 42s respectively. 44s on that in 1 are shown purely schematically by oblique lines.

Upon actuation of the friction clutch 30 become the slats 32 . 34 brought into frictional engagement with each other, leaving one of the superposition shaft 20 over the spur gear 24 and the gear 26 on the clutch basket 28 transmitted torque to the clutch hub 38 is transmitted. This torque will turn over the rigid with the clutch hub 38 connected gear 42 and the spur gear 44 on the output shaft 16 transfer. By a selective actuation of the friction clutch 30 For example, the amount of transmitted torque may be controlled as required. The superposition gearbox 22 is formed such that the rotational movement of the gear 44 with respect to the rotational movement of the superposition shaft 20 translated into fast.

The operation of the friction clutch 30 done by an actuator piston 46 wherein the actuation may be hydraulically and / or electrically controlled, for example. The actuation piston 46 presses on actuation of the outer and inner plates 32 respectively. 34 existing disc pack together, since this axially displaceable on the clutch basket 28 or the clutch hub 38 the friction clutch 30 are arranged. Between the actuator piston 46 and the disk pack is an operating portion 48 arranged, at least axially fixed to the clutch hub 38 connected is. The operating section 48 serves to transmit an axial movement of the clutch hub 38 on the slats 32 . 34 the friction clutch 30 , The axial movement of the clutch hub 38 is again to the result of the axial force F, by the interaction of the helical gears 42s . 44s of the gear 42 or the spur gear 44 be generated. A possible needle bearing - for example, between the Aktuierungskolben 46 and the operation section 48 - is in 1 not shown in detail.

Begins with an actuation of the friction clutch 30 a frictional engagement between the slats 32 and 34 occurs, so is by the onset of torque transfer from the clutch basket 28 on the clutch hub 38 the gear 42 driven, with the spur gear 44 combs. Due to the helical gears 42s . 44s of the gear 42 or the spur gear 44 , The already mentioned axial force F arises. The helical toothing is designed such that upon a forward movement of the vehicle, an actuation of the clutch to an axial displacement of the gear 42 leads to the right. In other words, the axial force F is directed to the right in this case. Due to the axially fixed coupling of the clutch hub 38 with the gear 42 also becomes the operating section 48 pressed to the right and contributes to the compression of the disk pack.

Thus, the through the Aktuierungskolben 46 applied Aktuierungskraft by means of the helical gears 42s . 44s generated axial force F supports, ie there is a self-reinforcing system. The larger the of the Aktuierungskolben 46 applied force is, the greater is the torque transfer over the drive Ver binding of the gear 42 and the spur gear 44 , which in turn increases the clutch operation assisting axial force F.

The compression of the disk pack is in the axial direction by a plate 50 and a warehouse 52 axially supported, with an axially fixed component 53 , such as the housing of the differential gear unit 10 , connected is. The axial support of the axial force F is effected by the rigid connection of the spur gear 44 with the output shaft 16 ,

It should be noted that the described effects of the rotation of the elements involved and the formation of helical gears 42s . 44s depend. The above explanations describe an example of a forward drive of the vehicle. When reversing, the interaction of the helical gears generates 42s . 44s an axial force F weakening the clutch actuation force (movement of the clutch hub 38 to the left), which is advantageous in many cases. In certain applications, the helical gears can 42s . 44s Also be designed such that in a "normal operation" - corresponding to a forward drive of the vehicle - a weakening axial force F is generated.

Special situations arise in tight cornering of a vehicle in which a curve outside wheel rotates much faster than a curve inside, namely faster than the gear ratio of the explained superposition gear 22 equivalent. Then, the above-mentioned attenuating effect may occur in the form of a moment reversal, which promotes self-opening of the system. This has the advantage that not the wheels on the wrong side of the vehicle additional torque is supplied when the maximum possible speed difference of the superposition gear 22 (For example, about 10%) is exhausted.

The helical gears 42s . 44s In particular, they may be designed such that their interaction provides up to two-thirds of the force actually acting on the disk pack. Ie. through the actuator piston 46 about one-third of the actuation force is provided, while two-thirds of the actuation force is provided by the actuation section 48 be applied.

The self-energizing effect makes it possible for the actuator piston 46 assigned actuator can be made smaller, which on the one hand leads to space savings, on the other hand, a lower energy consumption for actuation of the friction clutch 30 entails. In addition, such a self-reinforcing system is characterized by a greater dynamic range.

An alternative embodiment of the differential gear unit according to the invention 10 with a self-reinforcing function is in 2 shown. Also in 2 is only the right part of the differential gear unit 10 shown, wherein the differential gear 12 of the 2 essentially that of 1 corresponds (bevel gear differential gear). For the functionally same elements are in 2 the corresponding reference numerals of 1 used.

At the in 2 illustrated embodiment of the differential gear unit 10 goes the superposition wave 20 at her the differential gear 12 opposite end in an extended area over, which is a ring gear 54 having. The ring gear 54 stands with a spur gear 56 in driving connection, the axis of rotation 58 of the spur gear 56 parallel offset to the axis of rotation 60 the superposition wave 20 and the output shaft 16 is arranged.

The spur gear 56 is in axial and rotationally fixed connection with the clutch basket 28 the Rei advertising clutch 30 , Also the friction clutch 30 the in 2 illustrated embodiment has outer plates 32 and inner plates 34 on that with the clutch basket 28 or the clutch hub 38 rotatably but axially slidably coupled.

A difference from the embodiment of 1 is that in the present variant no countershaft 40 is provided. Rather, the friction clutch surrounds 30 the output shaft 16 in a desaxed arrangement.

The transmission of a torque of the clutch hub 38 - So if the friction clutch 30 is actuated and the clutch hub 38 from the clutch basket 28 is driven - on the output shaft 16 via a ring gear 62 , which rotatably and axially fixed to the clutch hub 38 connected is. The ring gear 62 combs with a spur gear 64 which is rigid with the output shaft 16 connected is.

In other words, this embodiment has two ring gear / spur gear pairings ( 54 . 56 and 62 . 64 ) to from the input member 14 over the superposition gearbox 22 a torque on the output shaft 16 to be able to transfer. The embodiment of the 1 uses two spur / spur gear pairings ( 24 . 26 and 42 . 44 ).

To that already by means of 1 To achieve the effect of self-boosting the friction clutch operation described have the ring gear 62 and the spur gear 64 helical gears 62s respectively. 64s on. During a forward travel of the vehicle and an actuation of the friction clutch 30 gets through by the helical gears 62s . 64s generated axial force F a movement of the clutch hub 38 generated in the axial direction, which is the operation of the friction clutch 30 through the actuator piston 46 supported. In other words, that is through stock 52 mounted and slidable in the axial direction clutch hub 38 upon actuation of the friction clutch 30 through one of the helical gears 62s . 64s generated axial force F shifted to the left, whereby the actuating portion 48 also moves to the left and together with the Aktuierungskraft the Aktuierungskolbens 46 the disk pack of the disks 32 . 34 compresses. The transmission of torque is thus a function of the Aktuierungskraft by the Aktuierungskolben 46 is exercised, this force by the action of helical gears 62s . 64s of the ring gear 62 or the spur gear 64 is reinforced.

The addition of the axial force F and the Aktuierungskraft of Aktuierungskolbens 46 can be realized in a simple manner by the at least axially fixed to the clutch hub 38 connected operating section 48 between the disk pack and the Aktuierungskolben 46 is arranged. The axial bearing of the friction clutch 30 takes place in 2 by the storage of the clutch basket 28 on the axially fixed component 53 about another camp 52 ,

The two described embodiments thus have a self-boosting of an applied by a clutch actuator Aktuierungskraft. By the helical gears 42s . 44s respectively. 62s . 64s This self-amplifying characteristic can be realized in a simple manner, ie the basic idea of the invention can be integrated in known differential gear units in an advantageous manner. The vorlie lowing invention enables the reduction of power consumption of the differential gear unit according to the invention, saves space and at the same time increases the dynamic range of the overall system.

10

Differential gear unit

12

differential gear

14

input member

16 16 '

output shaft

18

differential carrier

20 20 '

Superposition wave

22

Superposition gear

24

spur gear

26

gear

28

clutch basket

30

friction clutch

32

outer plate

34

inner plate

38

clutch

40

Countershaft

42

gear

42s, 44s, 62s, 66s

helical teeth

44

spur gear

46

Aktuierungskolben

48

actuating section

50

plate

52

camp

53

axialfestes component

54

ring gear

56

spur gear

58 60

axis of rotation

62

ring gear

64

spur gear

F

axial force

Claims (10)

Differential gear unit for actively controlling a torque distribution, in particular in a motor vehicle, with a differential gear ( 12 ), which is an input member ( 14 ) and two output shafts ( 16 . 16 ' ), each output shaft ( 16 . 16 ' ) a controllable friction clutch ( 30 ) associated with the input member ( 14 ) drivingly connected primary part and one with the associated output shaft ( 16 . 16 ' ), wherein at least one of the drive-effective connections comprises a first clutch-side toothing and a second toothing, which mesh with each other, characterized in that the first clutch-side toothing and the second toothing comprise helical toothings (FIGS. 42s . 44s . 62s . 64s ), and in that a respective component having the first coupling-side toothing with respect to the corresponding output shaft (11) 16 . 16 ' ) is axially displaceable, wherein the component has an actuating portion ( 48 ), which with the respective friction clutch ( 30 ) and wherein the helical gears ( 42s . 44s . 62s . 64s ) are selected so that an actuation of the respective friction clutch ( 30 ) is supported. Differential gear unit according to claim 1, characterized in that each of the friction clutches ( 30 ) an actuation piston ( 46 ) and a disk pack ( 32 . 34 ), wherein the respective actuating section ( 48 ) of the component on the same side of the respective disk pack ( 32 . 34 ) is arranged like the Aktuierungskolben ( 46 ). Differential gear unit according to claim 2, characterized in that the respective disc pack ( 32 . 34 ) at the actuator piston ( 46 ) and the operating section ( 48 ) facing away from the side axially supported. Differential gear unit after at least one the preceding claims, characterized in that a second toothing exhibiting Component is mounted axially fixed. Differential gear unit according to at least one of the preceding claims, characterized in that the helical toothings ( 42s . 44s . 62s . 64s ) are formed such that upon active actuation of the respective friction clutch ( 30 ) causes an axial movement of the first toothing component, so that the operation in the direction of engagement of the friction clutch ( 30 ) is supported. Differential gear unit according to at least one of the preceding claims, characterized in that each output shaft ( 16 . 16 ' ) a parallel offset countershaft ( 40 ) is associated, at which the corresponding friction clutch ( 30 ) is arranged, wherein the respective friction clutch ( 30 ) the countershaft ( 40 ) and adjacent to the associated output shaft (FIG. 16 . 16 ' ), and wherein at least one of the drive-effective connections is formed by a Stirnrad- / Stirnrad pairing. Differential gear unit according to claim 6, characterized in that the first clutch-side toothing on a first spur gear ( 42 ) is formed, the non-rotatably with the secondary part ( 38 ) of the respective friction clutch ( 30 ), wherein the second toothing on a second spur gear ( 44 ) is formed, the rotationally fixed and axially fixed to the output shaft ( 16 . 16 ' ) connected is. Differential gear unit according to at least one of claims 1 to 5, characterized in that the respective friction clutch ( 30 ) the associated output shaft ( 16 . 16 ' ) and its axis of rotation ( 58 ) with respect to the axis of rotation ( 60 ) of the output shaft ( 16 . 16 ' ), wherein at least one of the drive-effective connections is formed by a ring gear / spur gear pairing. Differential gear unit according to claim 8, characterized in that an associated output shaft ( 16 . 16 ' ) surrounding part of the friction clutch ( 30 ) a helical ring gear ( 62 ), which with a corresponding externally toothed spur gear ( 64 ) meshes with the associated output shaft ( 16 . 16 ' ) is rotatably connected. Differential gear unit according to claim 9, characterized in that the coupling-side first toothed component having the helical gear ( 62 ).