DE102017208666A1 - Powertrain for a four-wheel drive vehicle and motor vehicle with such a drive train - Google Patents

Abstract

A powertrain for an all-wheel drive vehicle having an engine (1) for providing propulsion power for propulsion of the four-wheel drive vehicle, first and second drivable vehicle axles (16, 6), said drivable vehicle axles (6, 16) adapted to transfer propulsion power to a road surface and wherein each of these vehicle axles (6, 16) has a differential gear (7, 10) for compensating differential speeds between drive wheels (8), wherein on each of the vehicle axles (6, 16) two of these drive wheels (8) are arranged and with a Speed change gear (2) for transmitting the drive power from the prime mover (1) to the drive wheels (8) and with a shift shaft (3) arranged to transfer the drive power from the speed change gear (2) to the second vehicle axle (6) and with a connection coupling (4), which in the torque transmission direction between the Gesc speed change gearbox (2) and the second vehicle axle (6) is arranged and with which the torque transmission from the speed change gearbox (2) to the second vehicle axle (6) is interruptible, wherein the drive train as an all-wheel freewheel (5) formed freewheel, characterized in that this four-wheel freewheel (5) is arranged in the torque transmission direction from the speed change gearbox (2) to the second vehicle axle (6) in front of the differential gear (7) of this vehicle axle (6), so that the selector shaft (3), based on the torque transmission between the connecting clutch (4 ) and the four-wheel freewheel (5) is arranged.

Description

The invention relates to a drive train for a four-wheel drive vehicle. A drive train according to the preamble of the first claim is known from DE 10 2014 208 604 A1 known.

The invention will be described below with reference to a passenger car, which is not to be understood as a limitation of the invention exclusively to this application. A general objective in the development of motor vehicles is to achieve high efficiency in the drive, i. To reduce losses. Next increases the available drive power, so that for the drive of such vehicles often called a four-wheel drive in which permanently (permanently) or at least temporarily (switchable) all wheels are driven, is used. In an all-wheel drive, the gearbox and drive shafts required for this, compared with a standard or front-wheel drive, the efficiency deteriorates.

From the prior art, in particular from the DE 10 2014 208 604 A1 , An all-wheel drive is known in which one of the drivable axles by means of a clutch and / or by means of at least one freewheel on demand or can be coupled off.

The object of the present invention is to provide an all-wheel drive with improved efficiency against this background. This object is achieved by a drive train according to the first claim or by a motor vehicle with such a drive train according to claim 6.

For the purposes of the invention, a drive train for an all-wheel drive vehicle is to be understood as a drive device which is set up to transfer drive power from a drive machine to a plurality of drivable drive wheels of the motor vehicle, preferably at least temporarily or preferably permanently to all wheels. Such a drive train is preferably set up for driving at least two drive wheels on two drivable vehicle axles.

For the purposes of the invention, a drivable vehicle axle is to be understood as an axle of the four-wheel vehicle which is set up to transmit drive power of the drive machine or the drive machines to at least two of these drive wheels and to guide these drive wheels. Preferably, a drivable vehicle axle has a so-called axle drive, preferably with or preferably consisting of a so-called differential, and axle shafts. The axle shafts are especially adapted for transmitting drive power from this axle drive to the drivable drive wheels of this vehicle axle. Preferably, the axle drive is designed as a bevel gear or preferably as a spur gear differential, or has such a differential.

For the purposes of the invention, one of these drive wheels is to be understood as meaning a rim with a tire, this drive wheel being set up to transmit drive power to the road surface.

For the purposes of the invention, a speed change gear means a gear device with which different gear ratios for the transmission of the drive power of the drive machine to the drive wheels is made possible. A speed change gear can be designed as a manually switchable or automatically switching transmission device. Speed change gears are known from the prior art in different designs.

For the purposes of the invention, a first vehicle axle is to be understood as meaning a preferably permanently drivable axle of the motor vehicle in which this drive train is received.

For the purposes of the invention, a second vehicle axle is to be understood as meaning a selectively drivable axle of the motor vehicle in which this drive train is received. The terms "first", "second" vehicle axle are preferably independent of the arrangement of the vehicle axle (front axle, rear axle) and in particular only designate whether the vehicle axle is permanently drivable (first vehicle axle) or selectively (second vehicle axle).

In the sense of the invention, a shaft is to be understood as meaning a shaft which is arranged relative to the torque transmission from the speed change gearbox to at least one of the drive wheels, or to the second vehicle axle, to the speed change gearbox and to the at least second transmission of torque from this speed change gearbox to the second Vehicle axle is set up. In particular, such a switching shaft is to be understood as a so-called articulated or cardan shaft.

For the purposes of the invention, a connection clutch is to be understood as meaning a selectively shiftable clutch which has a first operating state in which a torque can be transmitted with the connection clutch (engagement clutch closed), and a second operating state in which no torque can be transmitted with the connection clutch (connection clutch open). Further preferably, the Zuschaltkupplung is adapted to selectively interrupt the torque transmission to the second vehicle axle (switching off the four-wheel function) or produce (switching the four-wheel function). Preferably, the Zuschaltkupplung is designed as a frictionally engaged, preferably a form-fitting and particularly preferably as a reibformschlüssige coupling.

Further preferably, the Zuschaltkupplung is designed as a so-called "normal open" clutch, which is acted upon by a switching force to transfer them from the open to the closed state and to hold in this. With a "normaly open" clutch, the efficiency can be improved, since only in selected operating states the four-wheel drive is activated by pressing the connection clutch. Further preferably, the Zuschaltkupplung is designed as a so-called "normaly closed" coupling, which is acted upon by a switching force to convert them from the closed to the open state and to hold in this. In particular, by means of a "normaly closed" clutch high operational reliability can be achieved because the all-wheel drive is permanently available.

From the prior art a variety of different types of such couplings is known. The Zuschaltkupplung is thus particularly adapted to selectively interrupt the torque transmission from the speed change gear to the shift shaft or produce. If, in particular, the connection clutch is in its second operating state (opened), no torque transmission from the speed change gearbox to the second vehicle axle is made possible and thus the four-wheel drive is switched off.

For the purposes of the invention is to be understood by a four-wheel freewheel freewheel device. A freewheel or a freewheel device as such is known from the prior art, this is also often referred to as a super-hollow coupling. In particular, the four-wheel freewheel, based on the torque transmission from the speed change gearbox to the second vehicle axle, is arranged between the speed change gearbox and this vehicle axle. In particular, the four-wheel freewheel is thus arranged in front of the axle drive, or in front of the differential gear, this vehicle axle. Further preferably, the torque transmission from the shift shaft to the second vehicle axle can be interrupted with the four-wheel freewheel. Preferably, the Zuschaltkupplung and the four-wheel freewheel, based on the torque transmission from the speed change gear to the second vehicle axle connected in series or in series, so that no torque to the second vehicle axle is transferable, as soon as either the connection clutch or the four-wheel freewheel or both are open.

Further preferably, the four-wheel freewheel is arranged such that the shift shaft, based on the torque transmission, is disposed between the four-wheel freewheel and the connection clutch. In particular, by such an arrangement, it is possible that the switching shaft, during the drive of the vehicle exclusively on the first vehicle axle, is completely silent. In particular, this structure reduces the losses caused by the drive train and the efficiency of the drive train is thus improved.

In a preferred embodiment of the invention, the Zuschaltkupplung, based on the torque transmission from the speed change gearbox to the second vehicle axle, arranged in front of the four-wheel freewheel. Preferably, the four-wheel freewheel thus fahrzeugachsennah (based on the second vehicle axle) and the Zuschaltkupplung is arranged speed change gearbox. In particular, with such an embodiment of the invention results in a particularly good controllability of the drive train. In an operating mode with particularly high efficiency and in a driving situation in which no four-wheel drive is necessary, the Zuschaltkupplung is open so that no torque from the engine to the shift shaft is transferable and in particular, the shift shaft is stationary, since the four-wheel freewheel is open.

Preferably, the four-wheel freewheel is arranged such that on the open all-wheel freewheel no speed or torque from the second vehicle axle to the shift shaft transferable. The four-wheel freewheel is thus preferably arranged between the shift shaft and the second vehicle axle, that in the case of a push operation, in particular so when the four-wheel drive vehicle without being driven by or from the drive machines, the four-wheel freewheel is open. Further preferably, the four-wheel freewheel is arranged between the shift shaft and the second vehicle axle, that in the case of a motor drive of the second vehicle axle, in particular when the four-wheel vehicle is driven by providing drive power from the speed change gear on the second vehicle axle of the drive machine, the Four-wheel freewheel is closed.

In a preferred embodiment, the first vehicle axle is drivable via a first axle drive, preferably permanently driven. By "permanent" is to be understood in this sense in particular, that a permanent connection between the speed change gear and the first vehicle axle, via which a torque is transferable. In particular, such a drive train is particularly efficient since a permanent drive over the first vehicle axle, the second vehicle axle is hinzusteuerbar as needed and in the case that there is no need to drive the second vehicle axle, a large part of the drive train, in particular the shift shaft by means of the Zuschaltkupplung and the four-wheel freewheel, is shut down.

In a preferred embodiment of the invention, the first vehicle axle is designed as the front axle of a four-wheel drive vehicle. Further preferably, the second vehicle axle is designed as a rear axle of this four-wheel drive vehicle. Preferably, the drive train has a front angular gear and more preferably, drive power can be supplied from the drive machine via this angular gear of the switching shaft. Further preferably, the Zuschaltkupplung, based on the torque transmission from the drive machine to the second vehicle axle disposed behind the front angle gear and preferably the Zuschaltkupplung is arranged in front of the front angle gear. In particular, by the arrangement of the connection clutch in front of the front angle gearbox, it is possible to stop this gear when the second vehicle axle is switched off and so the efficiency of the drive train can be improved. In the event that the Zuschaltkupplung is located behind the front angle gear, a particularly simple construction of the drive train is possible.

Further preferably, the front angular gear on a hollow shaft, preferably this is adapted to supply drive power from the speed change gear. Preferably, the first vehicle axis extends at least partially in this hollow shaft. In particular, by a drive train with such a hollow shaft a particularly compact design is possible.

In a preferred embodiment of the invention, the four-wheel freewheel is designed as a switchable or lockable freewheel. Preferably, such a freewheel is by an external control command or due to its design blocking and preferably unlocked. In particular, when a vehicle is equipped with a drive train of the type described and when driving backwards with this vehicle, the need for a four-wheel drive, such a switchable or lockable freewheel can be locked in this reverse direction, or locks this automatically, and a drive of the second Vehicle axle is thus also possible in the reverse direction. Further preferably, the four-wheel drive, so the drive of the second vehicle axle, be selectively canceled by a switchable freewheel.

Further, a motor vehicle is provided, in particular a passenger car, which has a drive train of the type described above. In a preferred embodiment of the invention, the prime mover is designed as an internal combustion engine with internal combustion and preferably the internal combustion engine is designed in reciprocating design, which is preferably operable according to the diesel or preferably the Otto principle. Further preferably, the drive machine is incorporated in front transverse installation in this motor vehicle. Further preferably, the motor vehicle has at least one further drive machine and is designed in particular as a hybrid vehicle, preferably with the internal combustion engine as the first drive machine and an electric motor / generator as another drive machine.

• 1: eine schematisierte Darstellung eines aus dem Stand der Technik bekannten Allradantriebsstrangs,
• 2: eine schematisierte Darstellung einer ersten Ausführungsform der Erfindung,
• 3: eine schematisierte Darstellung einer zweiten Ausführungsform der Erfindung,
• 4: eine schematisierte Darstellung einer dritten Ausführungsform der Erfindung.

Hereinafter, preferred embodiments and individual features of the invention are explained in more detail with reference to the figures, in which:

• 1 FIG. 2: a schematized representation of a four-wheel drive train known from the prior art, FIG.
• 2 FIG. 2 is a schematic representation of a first embodiment of the invention, FIG.
• 3 FIG. 2: a schematic representation of a second embodiment of the invention, FIG.
• 4 : a schematic representation of a third embodiment of the invention.

In 1 is a schematic representation of a known from the prior art four-wheel system shown. This drive system has an internal combustion engine 1 with a speed change gearbox 2 on. About the transfer case 11 can by means of the front propeller shaft 15 and the rear propeller shaft 14 Drive power to the drivable rear axle 22 or to the drivable front axle 21 be transmitted. The main driving direction 20 of the four-wheel drive vehicle shows the directional arrow for all figures ( 1 to 4 ). Further, it is all illustrated drive systems ( 1 to 4 ) in common that the internal combustion engine 1 is designed as a front engine, the drive system according to the invention but is not limited to such a drive configuration, it can also be applied to rear-engine or mid-engine drive systems.

The drivable rear axle 22 has an axle drive 7a on. At the axle drive 7a is an actuator 12 provided, via which the torque transmission from the rear propeller shaft 14 on the drivable rear axle 6 is selectively interruptible. The transfer case 11 can be an actuator 13 over which the torque transmission to the drivable front axle 16 selectively interruptible. Four-wheel system known from the prior art either has the actuator 12 or 13 or no actuator on.

Next points the drive system 4 drivable wheels 8th on. The drivable rear axle 22 points next to the axle drive 7a also axle shafts 17 on, with which drive power from the axle drive 7a on the drivable wheels 8th is transferable. The drivable front axle 21 points next to the front axle drive 10 also axle shafts 17 on, with these is drive power from the front axle drive 10 on the drivable wheels 8th transferable to this axis.

Is in such a four-wheel drive system one of the drivable axles 21 . 22 switched off, ie the torque transmission from the speed change gearbox 2 to one of these axes 21 . 22 is interrupted, then rotates while driving the vehicle nevertheless the entire drive train unchanged and causes at least no-load losses.

In 2 a preferred first embodiment of the drive train according to the invention is shown, it is below essentially to the differences from the in 1 received drive system received. The in 2 shown drive train has a selectively driven vehicle axle, so-called second (drivable) vehicle axle 6 , And a permanently driven vehicle axle, so-called first (drivable) vehicle axle 16 , on. Next, this drive train has a front transverse internal combustion engine 1 as a prime mover. From the internal combustion engine 1 is drive power via the speed change gearbox 2 on the first vehicle axle 16 transferable.

For transmitting drive power to the second drivable vehicle axle 6 this drive train has the connection clutch 4 , the front angle gearbox 11 , the shift shaft 3 as well as the four-wheel freewheel 5 on. In an operating case, in which of the internal combustion engine 1 Drive power also on the second drivable vehicle axle 6 is to be transferred, the Zuschlopkupplung 4 closed, this transmits drive power to the front angle gearbox 11 , which is the selector shaft 3 set in rotation. Due to a sufficiently fast rotation of the shift shaft 3 closes the four-wheel freewheel 5 and from this is drive power to the axle drive 7 the second vehicle axle 6 and from this about the axle shafts 17 on the drivable wheels 8th the second vehicle axle 6 transferable.

In the described operating state, the torque transmission from the internal combustion engine 1 about the speed change gearbox 2 and the shift shaft 3 as well as the four-wheel freewheel 5 on the second drivable vehicle axle 6 allows.

In an operating case in which the second vehicle axle 6 not by the internal combustion engine 1 is to be driven, the Zuschaltkupplung 4 open, ie there is no torque transfer to the shift shaft 3 from the internal combustion engine 1 out instead. As a result of the shutdown of the switching shaft 3 via the connection coupling 4 and thereby adjusting speed ratios on the four-wheel freewheel 5 , opens this and the stem 3 as well as the front angular gear 11 stand still, although the four-wheel drive vehicle over the first vehicle axle 16 is driven further.

It follows that, in such a case, a large part of the powertrain will stall in propulsion of the 4x4 vehicle and cause no drag losses, and thus the powertrain efficiency will be superior to that of a prior art powertrain (see 1 ) improved.

In 3 a further preferred embodiment of the drive train according to the invention is shown. Here is the internal combustion engine 1 as a unit with the speed change gearbox 2 represented and arranged in front longitudinal installation.

The following is essentially based on the differences to those in 2 received powertrain received. At the in 3 shown powertrain is the first vehicle axle 16 , So the permanently drivable vehicle axle, arranged in the rear of the vehicle, based on the main direction of travel 20 , By means of the rear propeller shaft 14 is driving power from the speed change gearbox 2 on the axle drive 10 the first vehicle axle 16 transfer. By means of the front propeller shaft 15 is drive power to the front selectively driven vehicle axle, so-called second vehicle axle 6 , transferable.

In an operating case in which the second vehicle axle 6 is to be driven with, the Zuschaltkupplung 4 closed, this displaces the stem 3 in rotation and by the rotation of the switching shaft 3 closes the four-wheel freewheel 5 , From the closed all-wheel freewheel 5 is torque on the axle drive 7 the second vehicle axle 6 transferable. From this axle drive 7 is the drive power by means of the axle shafts 17 on the drivable wheels 8th the second vehicle axle 6 issued.

In 4 a further embodiment of the drive system according to the invention is shown. The front vehicle axle is permanently driven as a vehicle axle and thus as the first vehicle axle 16 educated. The rear axle of the vehicle is driven as needed vehicle axle and thus as a second vehicle axle 6 educated. The following is essentially based on the differences to those in the 2 and 3 received drive systems received.

Will the connection clutch 4 open, so is from the internal combustion engine 1 no torque on the stem 3 and thus on the second vehicle axle 6 transferable. With open connection coupling 4 opens the drive of the four-wheel drive the four-wheel drive 5 and the shift shaft 3 stand still. With closed connection coupling 4 , the shift shaft 3 set in rotation and when driving the four-wheel drive vehicle also closes the four-wheel freewheel 5 and it's about the clutch 4 , the shift shaft 3 , the four-wheel freewheel 5 as well as the axle drive 7 the second vehicle axle 6 Drive power via the axle shafts 17 on the drivable wheels 8th the second vehicle axle transferable.

In other words, with the invention, the emergence of Schleppmomenten, in particular by means of the four-wheel freewheel 5 , reduce. The four-wheel freewheel 5 is preferably directly in front of the differential or the axle drive 7 the second vehicle axle 6 , called secondary axis, attached. Thus, it is particularly achievable that only a part of the secondary drive (part of the drive train for driving the second vehicle axle 6 ) Is "dragged along".

In a mainly front-drive vehicle (see 2 . 4 ) with switchable four-wheel drive is preferably the adhesion between the speed change gear 2 and the shift shaft 3 if necessary with the connection coupling 4 generated, so the shift shaft 3 in pure front-wheel drive (second vehicle axle 6 is not actively driven) stops and thus causes neither losses nor a rotating inertia.

When connecting the four-wheel drive in such a drive train while driving the rear drive train, ie in particular the second vehicle axle 6 , with the help of the connection coupling 4 adapted to the speed traveled. Are the speed of the first vehicle axle 16 coupled portion of the drive train and the speed of the second vehicle axle coupled to the part of the drive train the same size, the drive wheels 8th the second vehicle axle 6 driven, as the four-wheel freewheel 5 , which is arranged in the torque transmission direction between these two parts of the drive train, now in the reverse direction (four-wheel freewheel 5 closed) is operated.

In particular, to enable reverse driving with four-wheel drive, is the four-wheel drive 5 preferably designed as a freewheel, which is lockable backwards, preferably by an external control command or preferably due to the design of this freewheel. This locking functionality can be done automatically (automatic freewheeling), or mechanically (by clamp), such freewheels are known in the art.

A particularly preferred embodiment of the invention is in 2 shown. There controls the internal combustion engine 1 about the speed change gearbox 2 both the axle drive 10 which is in the speed change gearbox 2 is included, the first vehicle axle 16 , as well as a hollow shaft. This hollow shaft is for torque transmission from the speed change gearbox 2 with the connection coupler 4 connected is. The first vehicle axle 16 , So the drive axle of the front wheels, sections running in the interior of the hollow shaft. The hollow shaft connects the second vehicle axle 6 if necessary, or when connecting the four-wheel drive, with the help of the connection coupling 4 torque-conducting with the speed change gearbox 2 , So can torque over the front angle gear 11 , the shift shaft 3 , the four-wheel freewheel 5 and the axle drive 7 the second vehicle axle 6 to the drive wheels 8th this vehicle axle 6 be transmitted. With open connection coupling 4 By contrast, fuel savings are achieved by avoiding drag torque and friction losses in the drive train.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

Speed change gear

3

shift shaft

4

in clutch

5

All-wheel freewheel

6

Second vehicle axle

7

Achsgetriebe the second vehicle axle

8th

drive wheel

9

Achsgetriebe the vehicle axle 22nd

10

Achsgetriebe the first vehicle axle

11

distribution gear

12

Electric actuator of 9, alternative to 13 available

13

Electric actuator of 11, alternative to 12 available

14

Rear PTO shaft

15

Front propeller shaft

16

First vehicle axle

17

axle shaft

20

Main direction

21

Drivable front axle

22

Drivable rear axle

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014208604 A1 [0001, 0003]

Claims (7)

A powertrain for an all-wheel drive vehicle having an engine (1) for providing propulsion power for propulsion of the four-wheel drive vehicle, first and second drivable vehicle axles (16, 6), said drivable vehicle axles (6, 16) adapted to transfer propulsion power to a road surface and wherein each of these vehicle axles (6, 16) has a differential gear (7, 10) for compensating differential speeds between drive wheels (8), wherein on each of the vehicle axles (6, 16) two of these drive wheels (8) are arranged and with a Speed change gear (2) for transmitting the drive power from the prime mover (1) to the drive wheels (8) and with a shift shaft (3) arranged to transfer the drive power from the speed change gear (2) to the second vehicle axle (6) and with a connection coupling (4), which in the torque transmission direction between the Gesc speed change gearbox (2) and the second vehicle axle (6) is arranged and with which the torque transmission from the speed change gearbox (2) to the second vehicle axle (6) is interruptible, wherein the drive train as an all-wheel freewheel (5) formed freewheel, characterized in that this four-wheel freewheel (5) is arranged in the torque transmission direction from the speed change gearbox (2) to the second vehicle axle (6) in front of the differential gear (7) of this vehicle axle (6), so that the selector shaft (3), based on the torque transmission between the connecting clutch (4 ) and the four-wheel freewheel (5) is arranged. Drive train for a four-wheel drive after Claim 1 , characterized in that the Zuschaltkupplung (4), based on the torque transmission from the speed change gearbox (2) to the second vehicle axle (6), in front of the four-wheel freewheel (5) is arranged. Drive train for an all-wheel drive vehicle according to one of the preceding claims, characterized in that the first vehicle axle (16) of the drive machine (1) via a first axle drive (10) is permanently driven. Drive train after Claim 3 , characterized in that the first vehicle axle (16) as a front axle and the second vehicle axle (6) is designed as a rear axle, that the switching shaft (3) via a front angular gear (11) drive power from the drive machine (1) can be supplied, that the Clutch (4), based on the torque transmission from the prime mover (1) to the shift shaft (3), in front of the front angular gear (11) is arranged. Drive system according to one of the preceding claims, characterized in that the four-wheel freewheel (5) is designed as a switchable or lockable freewheel. Motor vehicle with a drive system according to one of the preceding claims. Motor vehicle after Claim 6 , characterized in that the drive machine (1) is designed as an internal combustion engine in reciprocating design, which is operable according to the diesel or Otto principle and the drive machine (1) is installed in front transverse installation in the motor vehicle.

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