WO2005012768A1

WO2005012768A1 - Differential gear with variable torque distribution between the input shafts

Info

Publication number: WO2005012768A1
Application number: PCT/EP2004/007823
Authority: WO
Inventors: Theoder Gassmann
Original assignee: Gkn Driveline International Gmbh
Priority date: 2003-07-24
Filing date: 2004-07-15
Publication date: 2005-02-10
Also published as: DE10333641A1; DE10333641B4

Abstract

The invention relates to a differential gear (11) with variable torque distribution between two input shafts (13, 14), comprising a rotatably mounted, rotationally driven differential body (22), differential bevel wheels (23, 24) rotating peripherally with the differential body (22) and output shaft wheels (25, 26) rotationally mounted in the differential body and engaged with the differential bevel wheels (23, 24) for driving the output shafts (13, 14), in addition to a hydraulic system comprising two hydraulic machines (31, 32) arranged coaxially in relation to the output shafts (13, 14), said hydraulic machines respectively having a housing (33, 34), a rotor, an inlet side and an outlet side for hydraulic medium. The housing (33, 34) is rotationally fixed while the rotor can be driven rotationally in relation to the housing, wherein the inlet sides of the hydraulic machines (31, 32) are connected crosswise to the outlet sides of the hydraulic machines. At leas one hydraulic machine (31, 32) has an infinitely adjustable delivery volume flow. The rotationally driven part of one hydraulic machine (31) connected to one output shaft wheel (25) while the rotationally driven part of the other hydraulic machine (32) is connected to the other output shaft wheel (26).

Description

Differential gear with variable torque distribution between the output shafts

description

The invention relates to a differential gear with variable torque distribution between two output shafts. Differential gears of this type, which are referred to as differential gears with active yaw (active yaw differentials), are known and are used for variable torque distribution between the two drive wheels of a drive axle, such a torque increase and torque reduction, which is controlled independently of the speed to one or the other drive side, for improvement the driving dynamics when cornering and to increase driving safety in the event of vehicle instability.

Differential gears of this type are known from US ^' 296 (Honda), in which a part of the input torque is tapped from the input shaft for driving a countershaft before being introduced into the differential cage and the countershaft optionally distributes the torque to the output shafts via two controllable multi-plate clutches , These differential gears are complex and expensive.

From US 6,328,667 B1 differential gears of this type are known which comprise a hydraulic circuit with an external pump and a radial piston machine inserted into the differential gear, the housing of the radial piston machine with one of the output shafts or the differential cage of the differential gear and the cylinder block rotor of the radial piston machine with the other respectively. one of the output shafts is connected. The hydraulic control of radial piston machines and thus their integration into a differential gear is extremely complicated.

Proceeding from this, the present invention has for its object to provide a differential gear of the type mentioned in a simple design, wherein the torque distribution to the output shaft gears should be infinitely variable. The solution to this lies in a comprehensive differential gear with variable torque distribution between the output shafts

- a rotatably mounted, rotatable differential cage,

- differential gears rotating with the differential cage,

- And in the differential carrier rotatably mounted with the differential gears in engagement output shaft gears for driving the output shafts, as well as comprising a hydraulic system

two hydraulic machines arranged coaxially to the output shafts, each having a housing, a rotor, an inlet side and an outlet side for hydraulic medium,

the housing is fixed with respect to rotation and the rotor, in contrast, can be driven to rotate,

- The inlet sides of the hydraulic machines are connected crosswise to the outlet sides of the other hydraulic machines, and

- At least one of the hydraulic machines has an infinitely adjustable delivery volume flow, whereby according to a first solution variant the rotatably drivable part of the one hydraulic machine is connected to the one output shaft wheel and the rotatably drivable part of the other hydraulic machine is connected to the other driven shaft wheel, and wherein after a second Solution variant, the rotatably drivable part of a hydraulic machine with the differential carrier and the rotatably drivable part of the other hydraulic machine is connected to one of the output shaft gears.

Since the delivery volume of at least one machine is infinitely variable, the two machines can be continuously changed alternately as pumps or as hy Draulic motors function so that an active change in torque between the output shaft gears to generate an active yaw moment is possible with simple means regardless of the speed.

The housings of the two hydraulic machines are preferably held in a rotationally fixed manner and the rotors, which are connected to the output shaft gears of the differential gear or one of the output shaft gears and the differential cage, are rotatably arranged. The housing of the hydraulic machines can be firmly connected to a differential housing in which the differential carrier is rotatably mounted. This allows a coaxial arrangement of the hydraulic machines and the differential cage or the output shaft gears with little effort.

The hydraulic system comprises a reservoir for hydraulic medium, the non-return valves each sucking the inlet side of the hydraulic machine with the larger flow rate (pump) out of the reservoir in order to compensate for leakage. In this case, a control valve, a throttle and at least one pressure sensor are preferably provided in the hydraulic circuit.

The hydraulic medium of the hydraulic circuit is preferably formed by the lubricant contained in the differential gear housing, the differential gear housing forming the reservoir of the hydraulic circuit as a whole or with a specially designed sump.

In a neutral position, both hydraulic machines are set so that they have the same displacement volume and thus produce the same volume flow when the speed is the same, so that both run in the short circuit without pressure generation and no torque distribution effect occurs.

If the displacement volume and the resulting delivery volume flow of the first volume-changing machine exceeds that of the second with fixed delivery / oil, pressure will build up in the first hydraulic machine and the first machine acting as a pump will become the second one acting as a motor Drive hydraulic machine, whereby torque is shifted from the first to the second output shaft.

If the displacement volume of the first machine is set smaller than the fixed delivery volume of the second machine, the reverse situation arises, with the second hydraulic machine acting as a pump and the first hydraulic machine as a motor. Torque is redistributed from the second output shaft to the first output shaft.

The hydraulic pressure and the delivery volume of the machines determine the proportion of torque and the direction of the torque shift. A pressure sensor in the hydraulic circuit serves as an input variable for the control of the system, the pressure being representative of the torque ratio.

In the solution form in which the output shafts are connected to the two hydraulic machines, the torque difference (bias effect) between the left and right output shaft gears is the sum of the engine torque and the pump torque. In the solution in which the hydraulic machines are connected to one of the output shafts and the differential cage, the torque difference between the left and right output shaft gears is equal to the moment of the hydraulic machine that is drivingly connected to the corresponding output shaft and the output shaft gear.

A drain valve can be provided that opens in the event of a fault and overrides the torque variation function.

Preferred embodiments of the invention are shown in the drawings and are described below.

FIG. 1 shows a drive axle with a differential gear according to the invention with controllable torque distribution between two output shafts with two hydraulic machines in a symmetrical arrangement in a controllable hydraulic machine; FIG. 2 shows a drive axle of a differential transmission according to the invention with controllable torque distribution between the differential carrier and an output shaft with two hydraulic machines in a one-sided arrangement in a controllable hydraulic machine;

Figure 3 shows a drive axle with a differential gear according to the invention with controllable torque distribution between two output shafts with two hydraulic machines in a one-sided arrangement in a controllable hydraulic machine;

FIG. 4 shows a drive axle with a differential gear according to the invention with controllable torque distribution between two output shafts with two controllable hydraulic machines in a symmetrical arrangement;

Figure 5 shows a controllable hydraulic machine as a detail a) in longitudinal section b) in cross section;

FIG. 6 shows a differential gear of a drive axle according to FIG. 2;

FIG. 7 shows a differential gear of a drive axle according to FIG. 4.

In Figure 1, a drive axle of a motor vehicle is shown in a symbolic representation. Here, a differential gear 11 with an input shaft 12 and two output shafts 13, 14, two side shafts 15, 16 and two drive wheels 17, 18 are shown. The differential gear 11 comprises a gear housing 19 in which the input shaft 12 is mounted. The input shaft 12 drives a ring gear 21 via a pinion 20, which is firmly connected to a differential cage 22. The differential carrier 22 is rotatably mounted in the gear housing 19. With the differential cage 22, differential gears 23, 24 run around, which mesh with output shaft gears 25, 26. Via the differential gears 23, 24, the output shafts 13, 14 connected to the output shaft gears 25, 26 are connected to the input shaft 12 with differential action. the. With the gear housing 19, the housing 33, 34 of two hydraulic machines 31, 32 are fixedly connected, the drivable rotors of which are not shown in detail, are firmly connected to the output shafts 13, 14. A reversal of this configuration, ie a connection of the housings 33, 34 to the output shafts 13, 14 and a fixing of the rotors with respect to the gear housing 19 is also conceivable if a coaxial arrangement, as shown here, is dispensed with. The arrangement of the two hydraulic machines 31, 32 is on both sides of the differential gear 11 and essentially symmetrical. The hydraulic machines 31, 32 are connected to one another via lines 35, 36 in such a way that their input sides and output sides cooperate crosswise. From each of the lines 35, 36, an intake line 37, 38 goes to a reservoir 44 and a diverter line 39, 40 via a 2/2-way valve 41 also to the reservoir 44 43. The hydraulic machine 31 is designed with a variable volume flow, while the hydraulic machine 32 has a fixed volume flow over the speed. Both hydraulic machines are reversible machines, which means that they can be used as a pump as well as a motor. In the situation shown, the hydraulic machine 31 is operating e.g. B. as a pump and the hydraulic machine 32 as a motor. An input torque (Md ₁₂ ) on the input shaft 12 is evenly distributed by the differential gear 11 as wheel torques (Mdι ₇ and Mdι ₈ ) on the drive wheels 17, 18. Characterized in that the volume flow of the machine 31 is set larger than the volume flow of the machine 32 is a partial torque (Md3-ι) tapped from the wheel torque (Mdι ₇ ) on the wheel 17 for driving the pump and a substantially equal size via the motor power of the motor Motor torque (Md ₃₂ ) added to the wheel torque (Mdis) on .rad 18. Here, the pressure sides of the pump and motor are connected via one of the lines 35, 36, while pressure-free sides are connected via the other of the lines 35, 36. If the volume flow of the hydraulic machine 31 is set lower than the volume flow of the hydraulic machine 32, the function of the pump and motor reverses, so that the wheel torque (Md ₁₈ ) on the wheel 18 is reduced and the wheel torque (Mdι ₇ ) on Wheel 17 is increased. If the volume flow of both machines is set to the same, there is no effect, since the hydraulic machines pump hydraulic fluid in the short circuit.

In the position shown of the 2/2-way valve 41 (fail-safe), however, pressure medium is diverted via one of the lines 39, 40, while at the same time, in order to prevent dry running, pressureless medium is drawn in via one of the lines 37, 38.

A drive axle of a motor vehicle is shown in a symbolic representation in FIG. Here, a differential gear 11 with an input shaft 12 and two output shafts 13, 14, two side shafts 15, 16 and two drive wheels 17, 18 are shown. The differential gear 11 comprises a gear housing 19 in which the input shaft 12 is mounted. The input shaft 12 drives a ring gear 21 via a pinion 20, which is firmly connected to a differential cage 22. The differential carrier 22 is rotatably mounted in the gear housing 19. With the differential cage 22, differential gears 23, 24 run around, which mesh with output shaft gears 25, 26. Via the differential gears 22, 23, the output shafts 13, 14 connected to the output shaft gears 25, 26 are connected to the input shaft 12 with differential action. With the gear housing 19, the housing 33, 34 of two hydraulic machines 31, 32 are firmly connected, the driven rotors, not shown in detail, of which are firmly connected on the one hand to the output shaft 13 and on the other hand to the differential cage 22. The arrangement of the two hydraulic machines 31, 32 is on one side of the differential gear 11 with a through drive through one of the two machines. The hydraulic machines 31, 32 are connected to one another via lines 35, 36 in such a way that input and output sides interact in a crosswise manner. From each of the lines 35, 36, an intake line 37, 38 goes to a reservoir 44 and a diverter line 39, 40 via a 2/2-way valve 41 also to the reservoir 44 43. The hydraulic machine 31 is designed with a variable volume flow, while the hydraulic machine 32 has a fixed volume flow over the speed. Both hydraulic machines are reversible machines, which means that they can be used as pumps as well as motors. NEN. In the situation shown, the hydraulic machine 31 works as a pump and the hydraulic machine 32 as a motor. An input torque (Mdι ₂ ) on the input shaft 12 is evenly distributed by the differential gear as wheel torques (Mdir and Mdι ₈ ) on the drive wheels 17, 18. Characterized in that the volume flow of the engine is set to be greater 31 than the volume flow of the engine 32 ₍₇ Mdι) a part of torque (Md ₃₁₎ is tapped to drive the pump and the motor power of the motor as a motor torque (Md ₃₂₎ to the driving torque of the wheel torque ( Mdι ₂ ) of the differential cage 22 added. Here, the pressure sides of the pump and motor are connected via one of the lines 35, 36, while the pressure sides are connected via the other of the lines 35, 36. If the volume flow of the hydraulic machine 31 is set lower than the volume flow of the hydraulic machine 32, the function of the pump and motor reverses, so that the drive torque (Mdι ₂ ) on the differential carrier 22 is reduced and the torque Md- | ₇ on the wheel 17 is increased.

If the volume flow of both machines is set to the same, there is no effect, since the hydraulic machines pump hydraulic fluid in the short circuit.

A drive axle of a motor vehicle is shown in a symbolic representation in FIG. 3, which largely corresponds to the arrangements according to FIGS. 1 and 2. Here, the connection of the two hydraulic machines 31, 32 to the two output shafts 13, 14, as well as the hydraulic circuit of the hydraulic machines, are completely identical to the illustration in FIG. 1. To this extent reference is made to the description. The same details are given the same reference numbers. In contrast to FIG. 1, the geometric arrangement of the two hydraulic machines 31, 32 is on one side of the differential gear 11 with a through drive through one of the two machines 32 and is structurally similar in this respect to the arrangement according to FIG. 2.

FIG. 4 shows a drive axle of a motor vehicle in a symbolic representation, which largely corresponds to the arrangement according to FIG. 1. In particular, the arrangement of the two hydraulic machines 31, 32 on both sides for the dif- differential gear 1 and essentially symmetrical. The connection of the rotors of the two hydraulic machines with the two output shafts 13, 14 also corresponds to that in FIG. 1. In this respect, reference is made to the description there. The same details are given the same reference numerals. In a departure from FIG. 1, both hydraulic machines 31, 32 are continuously adjustable here. This allows a continuous change from the pump to the motor function of the two hydraulic machines by changing the displacement volume and thus the delivery volume flow of one and / or the other hydraulic machine. The mode of operation corresponds to that described in FIG. 1.

FIG. 5 shows a hydraulic machine in the form of a vane machine 51 which can be used as a hydraulic machine according to one of the preceding illustrations. The machine includes a housing 52 which can be flanged to a differential gear housing. The housing 52 is penetrated by an output shaft 53, which is sealed off from the housing 52 by means of sealing means 54. The output shaft 53 is to be connected to one of the side shaft gears or the differential carrier. The pump housing 55 sits in the housing 52 and is mounted eccentrically in the axis E with respect to the output shaft axis A. The pump housing 55 can be displaced about the axis E by means of a spindle drive 56 with a standing spindle 57 and a rising spindle nut 58. An electric motor 59 drives the spindle arrangement 57. The rotor 61, which is coaxial on the output shaft 53 with the axis A, runs in the pump housing 55 and, together with the former, forms individual pump chambers 60 through sealing rotor blades 62. Inlet and outlet channels in the end faces of the pump housing are not shown. In the concentric arrangement of rotor 61 and pump housing 55 shown, the delivery rate is 0. With increasing eccentric displacement of the pump housing 55 relative to the rotor 61, the pumping volume increases, since the size of the individual pump chambers 60 thereby changes over the circumference.

FIG. 6 shows a differential gear 111 designed as a planetary gear differential with a gear housing 119, in which a drive shaft 112 with a pinion 120 is mounted. The pinion 120 drives a ring gear 121, which is connected to a differential basket 122 is screwed on. The differential carrier 122 is designed as a ring gear of a planetary gear differential. The web 123 of the planet gear differential, in which planet gears 123, 124 are held, is connected to a first output shaft 113. The sun gear 126 of the planetary gear differential is connected to the second output shaft 114. A housing 151 is flanged to the gear housing 119, in which two hydraulic machines 131, 132 of the type described in FIG. 5 are held. The rotor of the first hydraulic machine 131 is rotatably connected to the web 123. The rotor of the second hydraulic machine 132 is rotatably connected to the sun gear 126 via the second output shaft 114. Both hydraulic machines 131, 132 are infinitely adjustable by design. A control disk 133, which is connected in a rotationally fixed manner to the housing 151, connects the pressure and suction sides of the hydraulic machines crosswise.

FIG. 7 shows a differential gear 211 with a gear housing 219 in which a drive shaft 212 with a pinion 220 is mounted. The pinion 220 drives a ring gear 221 which is screwed onto a differential cage 222. The differential gear is designed as a spherical gear differential. Differential gears 224, 225, which mesh with sideshaft gears 223, 226, are held in the differential cage 222. A first side shaft gear 223 of the differential gear is connected to a first output shaft 213; a second output shaft 214 of the differential gear is connected to a second output shaft 214. Housings 251, 252 are flanged to the gear housing 219 on both sides, in each of which hydraulic machines 231, 232 of the type described in FIG. 5 are held. The rotor of the first hydraulic machine 231 is non-rotatably connected to the first output shaft 213. The rotor of the second hydraulic machine 232 is non-rotatably connected to the second output shaft 214. Both hydraulic machines 131, 132 are infinitely adjustable by design. Differential gear with variable torque distribution between the output shafts

LIST OF REFERENCE NUMBERS

11 Differential gear 12 Input shaft 13 Output shaft 14 Output shaft 15 Half shaft 16 Half shaft 17 Wheel 18 Wheel 19 Gear housing 20 Drive pinion 21 Ring gear 22 Differential cage 23 Balance wheel 24 Balance wheel 25 Output shaft wheel 26 Output shaft wheel

31 hydraulic machine 32 hydraulic machine 33 housing 34 housing connecting line

connecting line

suction

diversion line

2/2 way valve

pressure sensor

throttle

reservoir

hydraulic machine

casing

output shaft

sealant

pump housing

spindle drive

spindle

Spindle nut E-motor Pump chamber Rotor Rotor wing

Differential gear input shaft output shaft output shaft 119 gearbox

120 sprockets

121 ring gear

122 differential cage

123 footbridge

124 planet gear

125 planet gear

126 sun gear

131 hydraulic machine

132 hydraulic machine

133 control disc

151 housing

211 differential gear

212 drive shaft

213 output shaft

214 output shaft

219 gear housing

220 sprockets

221 crown wheel

222 differential cage

223 sideshaft gear

224 differential wheel

225 differential wheel

226 sideshaft gear 231 hydraulic machine

232 hydraulic machine

251 housing

252 housing

Claims

Differential gear with variable torque distribution between the output shafts

1. Differential gear (11) with variable torque distribution between two output shafts (13, 14), comprising - a rotatably mounted, rotatably drivable differential cage (22), - with the differential cage (22) rotating differential gears (23, 24), - and in the differential cage (22) rotatably mounted with the differential gears (23, 24) in engagement with output shaft gears (25, 26) for driving the output shafts (13, 14), as well as with a hydraulic system comprising - two hydraulic coaxial to the output shafts (13, 14) Machines (31, 32), each having a housing (33, 34), a rotor, an inlet side and an outlet side for hydraulic medium, - wherein the housing (33, 34) is fixed with respect to rotation and the rotor, in contrast, can be driven to rotate , - The inlet sides of the hydraulic machines (31, 32) are connected crosswise to the outlet sides of the hydraulic machines, and - at least one of the hydraulic machine n (31, 32) has a continuously adjustable delivery volume flow, - the rotatably drivable part of the one hydraulic machine (31) is equipped with the one output shaft gear (25) and the rotatably drivable part of the other hydraulic machine (32) with the other driven shaft gear (26 ) connected.

Differential gear (11) with variable torque distribution between two output shafts (13, 14), comprising

- a rotatably mounted, rotatably drivable differential cage (22),

- with the differential cage (22) rotating differential gears (23, 24),

- And in the differential cage (22) rotatably mounted with the differential gears (23, 24) in engagement output shaft gears (25, 26) for driving the output shafts (13, 14), and comprising a hydraulic system

two hydraulic machines (31, 32) arranged coaxially to the output shafts (13, 14), each having a housing (33, 34), a rotor, an inlet side and an outlet side for hydraulic medium,

- The housing (33, 34) is fixed with respect to rotation and the rotor, in contrast, can be driven to rotate,

- The inlet sides of the hydraulic machines (31, 32) are connected crosswise to the outlet sides of the hydraulic machines, and

- at least one of the hydraulic machines (31, 32) has an adjustable flow rate,

- The rotatably drivable part of a hydraulic machine (31) is connected to one of the output shaft gears (25) and the rotatably drivable part of the other hydraulic machine (32) is connected to the differential cage (22).

Differential gear according to one of claims 1 or 2,

characterized,

that the housings (33, 34) of the hydraulic machines are firmly connected to a differential housing (19) in which the differential carrier (22) is rotatably mounted.

Differential gear according to one of claims 1 to 3, characterized in that that the hydraulic medium of the hydraulic circuit is formed by the lubricant contained in the differential gear housing (19), the differential gear housing (19) forming a reservoir (44) for the hydraulic circuit.

5. Differential gear according to one of claims 1 to 4, characterized in that a controlled valve (41) is provided in the hydraulic circuit for reducing the pressure.

6. Differential gear according to one of claims 1 to 5, characterized in that at least one pressure sensor (42) is provided in the hydraulic circuit.

7. Differential gear according to one of claims 1 to 6, characterized in that the hydraulic machines are internal gear pumps (gerotor machines).

8. Differential gear according to one of claims 1 to 6, characterized in that the hydraulic machines are axial piston machines. Differential gear according to one of claims 1 to 6,

characterized,

that the hydraulic machines are vane machines.