DE102011014703A1 - Drive unit for drive train of motor vehicle, particularly hybrid vehicle, has internal combustion engine, electric machine with rotor, and planetary gear having hollow wheel, sun wheel and planetary carrier - Google Patents

Abstract

The drive unit (10) has an internal combustion engine, an electric machine (26) with a rotor (30), and a planetary gear (16) having a hollow wheel (18), a sun wheel (22) and a planetary carrier (20). The electric machine also comprises a stator (28) corresponding to the rotor, which is rotatably held relative to the internal combustion engine. The stator partially surrounds the outer circumference of the rotor. A braking unit (46) is provided by which the hollow wheel is braked.

Description

The invention relates to a drive device for a motor vehicle according to the preamble of patent claim 1.

The DE 10 2005 008 148 A1 discloses a drive with an internal combustion engine and an electric machine, which are coupled to each other via a planetary gear, wherein the electric machine is designed so that both an inner rotor and an outer rotor are rotatably mounted, and wherein the electric machine in a motor or Generator operation operated and electrical energy can be exchanged with an electrical storage. An output line of the internal combustion engine is forwarded via a gear to a ring gear of the planetary gear, wherein the inner rotor of the electric machine is connected to a sun of the planetary gear and can be braked with an internal brake. The outer rotor is connected to a planet carrier of the planetary gear and can be delayed with an external brake. The planet carrier also represents the output of the system. It is envisaged that by means of the electric machine in all speed or power ranges, an additional torque or an additional speed can be added. This drive has a high complexity.

It is therefore an object of the present invention to provide a drive device for a motor vehicle, which has a low complexity and enables improved operation.

This object is achieved by a drive device for a motor vehicle having the features of patent claim 1. Advantageous embodiments with expedient and non-trivial developments of the invention are specified in the dependent claims.

Such a drive device for a motor vehicle, in particular for a hybrid vehicle, comprises an internal combustion engine, an electric machine comprising a rotor, as well as a ring gear, a sun gear and a planetary gear carrier having planetary gear. About the ring gear torque of the internal combustion engine in the planetary gear can be introduced. A torque of the electric machine in the planetary gear can be introduced via the sun gear and the rotor, and a torque can be diverted from the planetary gear via the planet carrier. In other words, the planet carrier provides an output of the planetary gear.

According to the invention it is provided that the electric machine comprises a stator corresponding to the rotor, which is held in a rotationally fixed relative to the internal combustion engine. Under a stator which is held against rotation relative to the internal combustion engine, should be understood in the context of the invention, a stator which is fixedly connected to the car and does not perform any rotational movement. Under the electric machine is advantageously designed as a so-called internal rotor machine, wherein the stator surrounds the rotor at least partially outer peripheral side.

The drive device according to the invention thus has a very low complexity, which keeps costs low. In particular, in the drive device according to the invention a control or regulation of the electric machine and thus an introduction of torque through the rotor in the planetary gear and / or a so-called torque superposition (torque addition and torque subtraction) are kept low in their effort because the stator is held against rotation ,

In addition, the drive device according to the invention allows a very effective speed and / or torque superposition, which is accompanied by a very effective and efficient operation of the drive device according to the invention.

The drive device according to the invention may have a first operating state in which a pure internal combustion engine operation is performed with a mechanical drive from the internal combustion engine via the planetary gear to the output. In this case, the sun gear is braked by means of a braking device and thus held against rotation while the ring gear driven by the internal combustion engine can rotate. In this case, any brake device provided is open for hard braking of the ring gear, so that the ring gear is not braked and held against rotation. In this operating state, the drive device advantageously has a total ratio of at least substantially i = 2 to i = 4. When i = 3 is a particularly advantageous translation, as it has, for example, a conventional manual transmission in a higher gear in conjunction with an axle ratio. This allows an advantageous and low-energy combustion engine driving the motor vehicle in particular longer cross-country trips. As a result, in particular the fuel consumption and thus the CO ₂ emissions of the internal combustion engine can be kept low. In this operating state, for example, the maximum speed of the motor vehicle with braked (rotationally held) electric machine is possible.

In addition, the drive device according to the invention can have a further operating state in which a purely electrical operation is performed. In this case, the ring gear is braked by means of the associated braking device and held against rotation, so thus is the internal combustion engine or is uncoupled, while the sun can rotate. The braking device of the sun gear is thus open and does not slow down the sun gear. If in the pure internal combustion engine operation, only a torque of the internal combustion engine in the transmission - and forwarded to the output and thereby driven the cars, so in the purely electrical operation, only one torque of the electric machine in the planetary gear on and forwarded to the output and driven by the car. In this purely electrical operation, the drive device advantageously has a total ratio of at least substantially i = 8 to i = 10, which also enables a particularly advantageous driving operation of the motor vehicle.

The drive device according to the invention represents a particularly advantageous drive device for hybrid vehicles, in particular for hybrid vehicles with the internal combustion engine in a function as range extender for a range of a motor vehicle, in which the motor vehicle can be operated without direct CO ₂ emissions by means of the electric machine wherein the electric machine is operated in a motor operation and supplied with electrical energy from an energy storage device, such as a battery, the drive unit. The internal combustion engine serves to further drive the motor vehicle when the electrical energy is exhausted and / or to recharge the electrical storage device, in which case the electric machine is operated in a generator mode and serves to recharge the energy storage device with electrical energy.

Equally possible is the representation of a so-called recuperation, in which kinetic energy of the moving motor vehicle degraded for braking desselbigen and is at least partially used by the electric machine in the generator mode to convert the kinetic energy at least partially into electrical energy and to charge the energy storage device. This is energetically particularly favorable in the case of the drive device according to the invention, in particular when the internal combustion engine is deactivated, and in particular in purely electrical operation, that is to say when the ring gear is held in a rotationally fixed manner. The drive device according to the invention offers the advantage that only an electrical machine including power electronics sufficient, a narrow-building gear disc can be used and the internal combustion engine can be fully utilized. In this case, the internal combustion engine can be used in particular for starting, for example, for driving onto a curb, since the planetary gear can be operated in combination with the electric machine as a continuously variable transmission.

The electric machine, however, offers the advantage, in particular over a friction clutch, of conducting superfluous energy during starting, which results from differential speeds, as electrical energy to the energy storage device and charging it instead of converting the energy between friction linings of the friction clutch into heat energy and thus energy loss. In a state of charge of the energy storage device below a threshold for starting the car against a resistance, so for example when starting on the mountain or against a curb, the internal combustion engine can be operated with slightly higher internal combustion engine speed and drive the electric machine as a generator. A control of the electric machine causes an increased due to a generated electric power counter-torque, so that a moment of the internal combustion engine increases accordingly until the planetary gear, which is connected to the output shaft and the initiated moments of the internal combustion engine and the electric machine keeps the balance , Resulting reaction torque on the output shaft is greater than the sum of the driving resistance of the motor vehicle and thus the car is set in motion. In the case of a curb drive, the scheme must, of course, as well as when manually starting in a conventional internal combustion engine driven vehicles the drive power provided back very quickly back, as soon as the resistance is overcome. When starting on the mountain a likewise controlled braking device is necessary, which releases the driven axle of the motor vehicle only when the drive torque exceeds the driving resistance and thus startup is possible to prevent rolling back of the motor vehicle on the mountain.

Furthermore, the drive device according to the invention as a further operating state may have a mixed operation: both the ring gear and the sun can rotate, so are not braked by means of the corresponding braking device and rotatably held, so that a torque from the internal combustion engine in the planetary gear introduced and the electric Machine can be operated in the generator mode or in the motor operation. In this operating state, the drive device allows a so-called load point shift. By appropriate control or regulation of the electrical Engine, the operating point of the internal combustion engine in the engine map can be moved so that it is located in a particularly fuel-efficient area.

To realize a comfortable ride without a so-called sawing operation of the internal combustion engine, the electric machine is fine to regulate a power to be dissipated in its counter-torque in the generator mode. In the drive device according to the invention, it is also possible to start the internal combustion engine without separate additional starting device in all operating conditions and start it. Is the car, so this is possible in a simple manner so that the drive is held against rotation, for example by braking connected to the output wheels. Then, the internal combustion engine can be started by the electric machine in a simple manner.

It is also possible to start the internal combustion engine at a transition from the purely electrical operation in the mixed operation, while the motor vehicle is driven electrically:
Although the drive device according to the invention makes it possible in principle to dispense with corresponding coupling devices in a torque flow between the internal combustion engine and the ring gear and / or in a torque flow between the electric machine or the rotor and the sun gear, so that the number of parts and thus the complexity, the Weight and the cost, depending on the comfort requirements for the car, can be kept very low.

However, it can be provided that in a torque flux between the internal combustion engine and the ring gear, a clutch device is arranged, by means of which the internal combustion engine with the ring gear for transmitting torque in a closed position of the clutch device coupled and in an open position of the clutch device, this coupling can be canceled. This allows a particularly favorable activation of the internal combustion engine to represent the transition from the purely electrical operation to the mixed operation or to the purely internal combustion engine operation and a particularly efficient and effective recuperation.

As a result, the internal combustion engine can be decoupled from the ring gear in the open position of the clutch device, for example in the case of purely electrical operation, and can be started and activated by means of a starting device assigned to the internal combustion engine. If the internal combustion engine is activated, the internal combustion engine can be coupled by moving the clutch device from the open position into the closed position with the ring gear, after or during the brake device, by means of which the ring gear is held in a rotationally fixed manner, and has released or releases the ring gear. This represents a particularly comfortable operation of the drive device and in particular a particularly comfortable transition between the individual operating states. Depending on whether a coupling similar to a clutch, such as a dog clutch or a friction clutch with a continuous, path-dependent coupling is used, the electric machine synchronizing effect or not.

If the coupling device between the internal combustion engine and the ring gear is not provided, then such a transition from the purely electrical operation to the hybrid operation or purely motor operation is possible such that the braking device is released for stalling the ring gear and by a particular small counter-pulse at the electric machine firmly coupled with the ring gear - initially still stationary - Internal combustion engine is taken as a result of the motor vehicle inertia and thereby started, but this means loss of comfort due to a hardly unavoidable jerking. Or it can only be at a standstill of the motor vehicle, d. H. when the drive axle is braked and consequently braked planet carrier, the internal combustion engine can be started by the electric machine.

The particularly efficient and effective recuperation can be represented by means of the coupling device between the internal combustion engine and the ring gear such that decelerates the motor vehicle, the internal combustion engine decoupled from the ring gear and the ring gear is braked by the corresponding braking device and rotatably held, thereby solely the electric machine with high transmission via the output with a torque or a rotational speed (of rotating wheels of the motor vehicle) is acted upon and slows down the vehicle over its controllable generator power in generator mode.

A possible coupling device in a torque flow between the electric machine and the sun wheel has the advantage that a safety element is thereby represented, for example, for full braking during pure electrical operation. By opening this coupling device, so that no torque transmission between the electric machine and the sun gear is more possible, it can be ensured that the moment of inertia of the electric machine does not destroy the abruptly stationary planetary gear.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respective combinations indicated, but also in other combinations or alone, without the scope of To leave invention.

The drawing shows

1 a schematic representation of a drive device for a hybrid vehicle with a planetary gear, which has a ring gear, a sun gear and a planet carrier, wherein with the ring gear an internal combustion engine, with the sun gear, a rotor of an electric machine is coupled and the planet carrier represents an output of the planetary gear which is coupled to a further gear stage, via which the drive axle of the motor vehicle can be driven.

2 a schematic representation of an alternative embodiment of the drive device according to 1 ;

3 a schematic representation of an alternative embodiment of the drive device according to the 1 and 2 ; and

4 a schematic representation of an alternative embodiment of the drive device according to the 1 to 3 ;

The 1 shows a drive device 10 in a drive train 12 a hybrid vehicle. The drive device 10 includes an internal combustion engine, which as a reciprocating engine 13 with a crankshaft 14 is trained. Furthermore, the drive device comprises 10 a planetary gear 16 which is a ring gear 18 , a planet carrier 20 as well as a sun wheel 22 having. At the planet carrier 20 are planet gears 25 rotatably held, which with the ring gear 18 and with the sun wheel 22 comb. The sun wheel 22 is non-rotatable with a sun shaft 24 connected.

Again 1 it can be seen, is the crankshaft 14 with the ring gear 18 coupled and non-rotatably connected, so that a torque of the reciprocating engine 13 over the ring gear 18 in the planetary gear 16 can be initiated.

Furthermore, the drive device comprises 10 an electric machine 26 with a stator 28 and one with the stator 28 interacting rotor 30 , The rotor 30 is rotatable with the sun shaft 24 connected, so that a torque of the electric machine 26 over the rotor 30 , the sun wave 24 and the sun wheel 22 in the planetary gear 16 can be initiated.

The electric machine 26 is designed as an internal rotor machine. This means that the stator 28 the rotor 30 Outside circumference surrounds and relative to the reciprocating engine 13 rotatably held and thus arranged vehicle-mounted.

The planet carrier 20 of the planetary gear 16 provides an output of the planetary gear 16 is and is with an output shaft 32 rotatably connected, in turn, with a gear 34 a gear stage 36 the drive device 10 rotatably connected.

The gear stage 36 includes an intermediate gear 38 , as well as another gear 40 which with wheels 42 the hybrid vehicle is coupled so that the wheels 42 from the drive device 10 can be driven.

Like in the 1 is shown schematically, the wheels 42 about an axis to be driven 44 interconnected with the gear 40 , For example, via a differential case of a differential with the driven axle of the motor vehicle 44 connected is. It is understood that in the 1 shown drive device 10 as well as in the 1 shown powertrain 12 readily transferable to other drive trains, for example, with an independent suspension, the wheels 42 be driven via respective, in particular homokinetic propeller shafts and optionally via a differential to compensate for differential speeds.

The drive device 10 has a low complexity and allows a particularly efficient and effective torque and speed superposition of torques and speeds, which of the reciprocating engine 13 and the electric machine 26 in the planetary gear 16 be initiated. In this case, the electric machine 26 be operated as a motor in a motorized operation. In the process, the electric machine becomes 26 with the electrical energy from one in the 1 not shown battery powered. Equally possible is the electric machine 26 operate in a generator mode, the electric machine 26 or the sun wheel 22 and the sun wave 24 represent another downforce. In generator mode, the electric machine 26 used in the planetary gear 16 from the reciprocating engine 13 and / or from the wheels 42 introduced torques and thus convert mechanical energy into electrical energy to Thus, the battery with electrical energy to feed and charge it.

The planetary gear 16 can have a level translation i ₁₂ or i _HS , which is at least substantially minus three (-3). This stand translation results from the following formula i ₁₂ = i _HS = H / S where H is the number of teeth of the ring gear 18 and S is the number of teeth of the sun gear 22 designated. Because the ring gear 18 has an internal toothing, the number of teeth of the ring gear is a negative value and accordingly to use in the above formula. The number of teeth H is thus for example -60, while the number of teeth S, for example 20 is. The number of teeth P of the planet gears 25 is for example 20 ,

wobei n₁ bzw. n_EM die Drehzahl des Sonnenrads und damit des Rotors 30 der elektrischen Maschine 26, n₂ bzw. n_VM die Drehzahl des Hohlrads 18 und damit der Hubkolbenmaschine 13 und n_S bzw. n_AB die Drehzahl des Planententrägers 20 bezeichnen, ergeben sich die folgenden aufgeführten Drehzahlverhältnisse.From the so-called Willis equation:

where n ₁ or n _EM the speed of the sun gear and thus the rotor 30 the electric machine 26 , n ₂ or n _VM the speed of the ring gear 18 and thus the reciprocating engine 13 and n _S or n _AB the speed of the tarpaulin carrier 20 denote, the following listed speed ratios result.

Is the output shaft 32 and thus the planet carrier 20 for example, by means of a service brake braked wheels 42 held against rotation, it being the wheels 42 For example, is front wheels of the hybrid vehicle, it follows:

Will the drive device 10 For example, operated in a purely electric mode, so are the hybrid vehicle and thus the wheels 42 exclusively with the electric machine 26 driven. This is the ring gear 18 and thus the reciprocating engine 13 by means of a braking device 46 braked and held against rotation. According to the Willis equation, the following speed ratio results:

In contrast, the drive device 10 be operated in a purely internal combustion engine operation, the hybrid vehicle and thus the wheels 42 exclusively with the reciprocating engine 13 are driven. Here are the sun gear 22 and thus the rotor 30 via a braking device 48 braked and held against rotation. Then the following speed ratio results:

From the Willis equation also follows the following, general speed ratio: n _AB = 3 / 4n _VM + 1 / 4n _EM

wobei n_End die Drehzahl des Zahnrads 40 bezeichnet, ergibt sich in Kombination mit den vorgenannten Drehzahlverhältnissen im rein verbrennungsmotorischen Betrieb (Sonnenrad 22 drehfest gehalten):

und daraus eine Gesamtübersetzung i_gesVM der Antriebseinrichtung 10 im rein verbrennungsmotorischen Betrieb: 8,8 / 3 = i_gesVM = 2,9 The gear stage 36 has, for example, a translation i _ÜB of 2.2. With

where n _{end is} the speed of the gear 40 referred to, results in combination with the aforementioned speed ratios in pure internal combustion engine operation (sun 22 held against rotation):

and from this a total ratio i _gesVM the drive _device 10 in purely internal combustion engine operation: 8.8 / 3 = i _gesVM = 2.9

und daraus eine Gesamtübersetzung i_gesVM der Antriebseinrichtung 10 im rein elektrischen Betrieb 8,8 = i_gesEM In purely electrical operation (with non-rotatably held ring gear 18 ) surrendered:

and from this a total ratio i _gesVM the drive _device 10 in pure electrical operation 8.8 = i _total

A balance of forces at Planetenradumfang provides the following moment balance: M _VM = -3M _EM this moment balance means: becomes the planet carrier 20 rotatably by means of, for example, a parking brake of the driven axis 44 held the motor vehicle and is a torque M _{EM of} the electric machine 16 over the rotor 30 in the planetary gear 16 initiated, so this torque M _EM in a threefold amount as the torque M _VM via the ring gear 18 on the crankshaft 14 transferred and into the reciprocating engine 13 , for example, to start, initiated. The negative sign here means that the direction of rotation of the torque M _{VM is} opposite to the direction of rotation of the torque M _EM .

Furthermore, the following current account results: M _AB * n _AB = M _VM * n _VM + M _EM * n _EM where M _{AB is} a torque of the output shaft 32 , n _{AB is} a speed of the output shaft 32 , n _VM a torque of the reciprocating engine 13 , n _{VM is} a speed of the reciprocating engine 13 , M _EM a torque of the electric machine 26 n _{EM is} a speed of the electric machine 26 or its stator 30 and with it the sun wheel 22 describe.

Like in the 1 through an area 50 is indicated, can in a torque and / or force flow between the internal combustion engine 13 and the ring gear 18 a coupling device such as a dog clutch may be arranged.

The 2 shows an alternative embodiment of the drive device 10 according to 1 , Again 2 it can be seen, the output via the planet carrier 20 , the output shaft 32 and the gear stage 36 , in particular in the axial direction of the sun shaft 24 , between the sun wheel 22 and the electric machine 26 arranged. In comparison with the drive device 10 according to 1 is thus the electric machine 26 not between the gear stage 36 and the planetary gear 16 but arranged outside. This avoids the electric machine 26 a transmission oil space for the planetary gear 16 and the gear stage 36 divided into two rooms. As a result, only a single common transmission oil space for the planetary gear 16 and the gear stage 36 represented, in which lubricant, in particular lubricating oil, for lubricating and cooling the overall transmission of planetary gear 16 and gear stage 36 can be included. This means that the electric machine 26 can run dry so to speak and different embodiments of electrical machines are technically easily externally flanged to a transmission housing of the overall transmission.

The 3 shows an alternative embodiment of the drive device 10 , While the 1 and 2 the drive device 10 show in a so-called transverse installation in a motor vehicle, the shows 3 the drive device 10 in a longitudinal installation. Again 3 it can be seen, is the output shaft 32 with a propeller shaft 54 rotatably coupled. The PTO shaft 54 includes propeller shaft parts 56 , which have a joint 58 articulated with each other and over a joint 60 with the output shaft 32 are hingedly connected. The gear 34 is formed, for example, as a bevel gear and meshes with the gear formed as a crown gear 40 the gear stage 36 , It may be advantageous as well as drive devices for a transverse installation in a motor vehicle, the crown wheel 40 Part of a transfer case, not shown, a so-called differential, the axis to be driven in each case 44 of the motor vehicle, as is conventional in conventional drive devices for motor vehicles with pure internal combustion engine drive.

The 4 shows the drive device 10 in a further embodiment in a longitudinal installation. As with the drive device 10 according to 2 is the output between the sun gear 22 and the electric machine 26 arranged. In other words, the electric machine 26 arranged outside the output.

The output includes an optional switching group 52 which has two gears, between which can be switched. A first of the gears of the switching group 52 is associated with a first gear pair, which one with the output shaft 32 non-rotatably connected gear 62 as well as a switch muffle 64 with the propeller shaft 54 rotatably coupled gear 66 includes.

The second of the gears is associated with a second pair of gears, which one with the output shaft 32 non-rotatably connected gear 68 as well as by means of the sliding sleeve 64 with the propeller shaft 54 rotatably coupled gear 70 includes. The sliding sleeve 64 can of course also on the output shaft 32 are located, bringing the loose wheels then also on the output shaft 32 located and the fixed wheels on the propeller shaft 54 , The optional switching group 52 Thanks to its two-speed switchable gearbox, it can display and cover speed ranges up to more than 250 km / h or when starting with the internal combustion engine 13 against high resistors while a buffered by the battery generator power of the electric machine 26 lower or with a low-torque internal combustion engine 13 Comfortable starting at low battery voltage.

LIST OF REFERENCE NUMBERS

10

driving means

12

powertrain

13

Internal combustion engine

14

crankshaft

16

planetary gear

18

ring gear

20

planet carrier

22

sun

24

sun wave

25

planet

26

electric machine

28

stator

30

rotor

32

output shaft

34

gear

36

gear stage

38

gear

40

Gear (eg on the differential housing of the driven axle of the motor vehicle)

42

wheel

44

To be driven axle of the motor vehicle

46

braking means

48

braking means

50

Area

52

switching group

54

propeller shaft

56

PTO shaft part

58

joint

60

joint

62

gear

64

shift sleeve

66

gear

68

gear

70

gear

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 102005008148 A1 [0002]

Claims (8)

Drive device ( 10 ) for a motor vehicle, in particular a hybrid vehicle, with an internal combustion engine ( 13 ), with a rotor ( 30 ) comprehensive electric machine ( 26 ) and with a ring gear ( 18 ), a sun wheel ( 22 ) and a planet carrier ( 20 ) having planetary gear ( 16 ), via its ring gear ( 18 ) a torque of the internal combustion engine ( 13 ) in the planetary gear ( 16 ), via the sun wheel ( 22 ) and the rotor ( 30 ) a torque of the electric machine ( 26 ) in the planetary gear ( 16 ), and via its planet carrier ( 20 ) a torque from the planetary gear ( 16 ), characterized in that the electric machine ( 26 ) one to the rotor ( 30 ) corresponding stator ( 28 ), which relative to the internal combustion engine ( 13 ) is held against rotation. Drive device ( 10 ) according to claim 1, characterized in that the stator ( 28 ) the rotor ( 30 ) at least partially surrounds the outer peripheral side. Drive device ( 10 ) according to one of claims 1 or 2, characterized in that a braking device ( 46 ) is provided, by means of which the ring gear ( 18 ) is braked. Drive device ( 10 ) according to one of the preceding claims, characterized in that a braking device ( 48 ) is provided, by means of which the sun gear ( 22 ) is braked. Drive device ( 10 ) according to one of the preceding claims, characterized in that the internal combustion engine ( 13 ) via a coupling device with the ring gear ( 18 ) can be coupled. Drive device ( 10 ) according to one of the preceding claims, characterized in that the electric machine ( 26 ) via a coupling device with the sun gear ( 22 ) can be coupled. Drive device ( 10 ) according to one of the preceding claims, characterized in that the planet carrier ( 20 ) with a transmission device ( 36 ), in particular a gear stage ( 36 ), coupled or coupled, via which a torque from the drive device ( 10 ) is derivable. Drive device ( 10 ) according to one of the preceding claims, characterized in that the amount of stand ratio (i ₁₂ , i _HS ) of the planetary gear ( 16 ) is at least substantially three.

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