Note: Descriptions are shown in the official language in which they were submitted.
CA 02463359 2004-04-07
DRIVE ARRANGEMENT FOR THE DRIVE OF ATTACHED IMPLEMENTS FOR A
VEHICLE
Field of the Invention
The invention concerns a drive arrangement for the drive of attached
implements for a vehicle, in particular an agricultural or industrial utility
vehicle, with
a combination gearbox, an electrical machine and a power take-off shaft, where
a
gearbox interface of the combination gearbox can be driven by an internal
combustion engine and where the electrical machine is connected to a second
gearbox interface of the combination gearbox. Furthermore the present
invention
concerns a vehicle with such a drive arrangement.
Back4round of the Invention
From DE 197 49 074 A1 an agricultural utility vehicle with a mechanical-
electrical torque division gearbox is known. Here an internal combustion
engine is
connected with a first gearbox interface of a combination gearbox and an
electrical
machine is connected with a further gearbox interface of the combination
gearbox.
The combination gearbox is used for the forward propulsion drive of the
utility vehicle.
A generator driven by the engine drive shaft is provided, that supplies the
electrical
machine with electrical power. Thereby a mechanical-electrical torque division
can be
achieved, that makes possible an infinitely variable forward propulsion drive
of the
utility vehicle, where a higher efficiency can be attained in contrast to a
conventional
torque division gearbox configured as a hydrostatic drive. On the other hand
the
power take-off shaft is connected to the internal combustion engine over a
purely
mechanical gearbox, so that the power take-off shaft rotational speed is in a
fixed
relationship to the rotational speed of the internal combustion engine.
Operating implements can be adapted to an agricultural utility vehicle, for
example, to a tractor, that must be driven mechanically over a power take-off
shaft of
the utility vehicle. Such an operating implement is, for example, a non-self
propelled
rotobaler. In the sense of the present invention the drive interface is
understood to
mean an attached implement driven by the vehicle, that makes a mechanical
torque
available.
CA 02463359 2004-04-07
When operating implements that must be operated at a constant input
rotational speed, are adapted to a vehicle with a power take-off shaft
according to DE
197 49 074 A1, the internal combustion engine must be operated at a constant
rotational speed for trouble-free operation of the operating implement, since
the power
take-off shaft is in a fixed rotational speed relationship to the rotational
speed of the
internal combustion engine. Thereby an infinitely variable gearbox must be
provided
in the drive-line of the main propulsion drive, in case that a change in the
propulsion
speed of the vehicle is to be performed. This is expensive and costly since
this
requires an infinitely variable power shift gearbox.
In case that operating implements are to be attached to a vehicle which must
be operated at a power take-off shaft speed proportional to the forward
propulsion
velocity of the vehicle, a trouble free operation is only possible if the
rotational speed
of the internal combustion engine is actually proportional to the forward
propulsion
velocity. If the wheels of the vehicle spin, for example, on a tractor in the
field, the
forward propulsion velocity of the vehicle is reduced. In case the power take-
off shaft
speed remains unchanged, the proportionality of the power take-off shaft speed
to the
forward propulsion velocity is changed and the rotational speed of the
operating
implement will increase relative to the forward propulsion velocity. In sowing
machines
this can have the effect that the plants are planted at irregular intervals.
The task underlying the invention is seen in the need to define a drive
arrangement for attached implements for a vehicle of the aforementioned type
through
which the above problems are overcome. In particular a constant power take-off
shaft
rotational speed should be made available despite a varying rotational speed
of the
internal combustion engine. Furthermore with a generally constant internal
combustion engine rotational speed a variable power take-off shaft rotational
speed
should be generated.
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CA 02463359 2004-04-07
Summary of the Invention
According to the invention a drive arrangement of the type noted initially is
characterized by the power take-off shaft that is connected with a third
gearbox
interface of the combination gearbox. Thereby an attached implement requiring
a
constant input rotational speed can be operated at an essentially constant
power take-
off shaft rotational speed by a variation of the internal combustion engine
rotational
speed. The power take-off shaft rotational speed is held constant by the
electrical
machine that is operated or controlled in such a way that it equalizes a
variation in the
rotational speed of the internal combustion engine through the combination
gearbox.
The electrical machine could, for example, be supplied by a battery or a
dynamo.
Thereby the vehicle speed or the rotational speed of the internal combustion
engine
can also be varied to great advantage without an infinitely variable gearbox
in the
vehicle driveline, where the power take-off shaft rotational speed can be held
constant
with the aid of the electrical machine.
But a power take-off shaft rotational speed proportional to the vehicle speed
can be realized despite spinning vehicle wheels by means of the invention, in
that the
electrical machine is operated or controlled in such a way that the power take-
off shaft
rotational speed is proportional to the actual vehicle speed. For this purpose
a vehicle
speed sensor could be provided that detects the actual vehicle speed.
Therefore to
great advantage fundamentally no mechanical power take-off shaft gearbox is
required, because a variation of the rotational speed of the power take-off
shaft can be
attained with the drive arrangement according to the invention.
An overload capacity of the power take-off shaft or the power take-off shaft
driveline is provided to great advantage by the drive arrangement according to
the
invention, since any possible torque peaks transmitted from the attached
implement to
the power take-off shaft driveline can be absorbed by the electrical machine
and
thereby compensated. For this purpose the electrical machine must be
controlled, if
necessary, by a corresponding control an-angement. In this connection the
power
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CA 02463359 2004-04-07
take-off shaft driveline is understood to include particularly the components
arranged
between the power take-off shaft and the internal combustion engine.
According to a preferred embodiment of the invention the combination
gearbox is provided with a circulating gearbox, in particular a planetary
gearbox.
Preferably the planetary gearbox is designed in such a way that the internal
combustion engine as well as the electrical machine operate in a region of
favorable
efficiency, in which high torques can also be transmitted to the power take-
off shaft.
Here a gearbox interface of the planetary gearbox operating as input is
connected to
the internal combustion engine. A gearbox interface of the planetary gearbox
operating as input as well as output is connected with the electrical machine.
Finally a
gearbox interface of the planetary gearbox operating as output is connected to
the
power take-off shaft.
In a very particularly preferred embodiment a brake is provided with which
the power take-off shaft can be stopped. In case that the combination gearbox
is
driven by the internal combustion engine over the gearbox interface and the
power
take-off shaft is stopped by the brake, the entire mechanical energy supplied
to the
combination gearbox is supplied to the electrical machine. Thereby electrical
energy
can be generated to great advantage with the electrical machine, that can be
conducted, for example, to electrical devices or to a battery. In so far that
this is not
an electrical machine driven by an internal combustion engine in long-term
operation, for example, in the form of a conventional dynamo of a vehicle, but
an
electrical machine that can be activated if required by the stopping of the
brake of
the power take-off shaft interacting with the combination gearbox. Since a
power
take-off shaft is usually designed for the transmission of high torques, the
electrical
machine can also generate correspondingly high electrical power to great
advantage
with corresponding dimensioning. In case that the power take-off shaft is
stopped
with the brake and thereby the gearbox interface of the power take-off shaft
is
stopped, the gearbox interface connected with the electrical machine operates
as
output.
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CA 02463359 2004-04-07
In a particularly preferred embodiment a further electrical machine is
provided, that can be driven directly or indirectly by the internal combustion
engine.
The further electrical machine could be connected over a positive locking
connection
with the drive shaft of the internal combustion engine. A direct arrangement
of the
electrical machine on the drive shaft could also be provided as described, for
example, by DE 197 49 074 A1. In so far as the further electrical machine as
is the
electrical machine can be driven to great advantage with a high torque on the
basis
of the direct or indirect mechanical drive by the internal combustion engine,
so that,
for example, electrical devices with high power output can be operated.
Particularly for the operation of electrical devices that require a large
amount
of electrical power, the electrical machine and the further electrical machine
can be
operated as generator. For this purpose finally the electrical machine or the
further
electrical machine must be switched correspondingly, so that, for example, the
rotary
current generated by both electrical machines can be conducted directly to
electrical
devices that are, for example, in the form of rotary current motors. If a
particularly
high level of electrical power is required the power take-off shaft can be
stopped by
the brake, whereby the electrical machine is driven with maximum rotational
speed.
The further electrical machine is driven directly or indirectly by the
internal
combustion engine, and both electrical machines can be operated as generator.
The electrical machine or the further electrical machine could also be
operated as electric motor. Preferably the electrical machine is operated as
an electric
motor. In this case the electrical machine as well as the internal combustion
engine
supplies power to the combination gearbox which delivers the combined power
output
to the power take-off shaft. Here the electrical machine can be operated in
two
directions of torque, whereby the rotational speed of the power take-off shaft
can be
varied to great advantage over a wide rotational speed range. In this way an
infinitely
variable controlled power take-off shaft operation is possible with the
mechanical-
electrical torque division gearbox. However, the further electrical machine
can also be
,_
CA 02463359 2004-04-07
operated as an electric motor, in order to permit, for example, mechanical
feedback of
the energy generated by it.
Preferably a rectifier is associated with the electrical machine and/or the
further electrical machine, with which each of the electrical machines can be
switched
in both directions of rotation and/or both directions of torque (four quadrant
operation).
The rectifier preferably converts the alternating cun-ent generated by the
electrical
machine operating as generator into direct cun-ent, and feeds it into a direct
current
network or into an electrical storage unit. In case that an electrical machine
is to be
operated as electric motor, the rectifier converts the direct current taken
out of the
direct current network or out of the electrical storage unit into alternating
current or
rotary (three phase) current, whereby the electrical machine can be operated
as an
alternating or rotary current machine.
The drnre arrangement can be applied in a multiplicity of ways and can be
variable if a control arrangement is provided that controls the internal
combustion
engine or a control of the internal combustion engine, the electrical machine,
the
further electrical machine, at least one rectifier and/or the brake. This
control
arrangement can configure, for example, the control arrangement by releasing
the
brake and by a configuration of the rectifiers of the electrical machine to an
electric
motor and the further electric machine to a generator in such a way that a
torque .
division mechanical-electrical gearbox is realized. Here a part of the torque
generated
by the internal combustion engine and another part of the torque generated by
the
electrical machine is transmitted to the power take-off shaft over the
combination
gearbox. Thereby a generally constant power take-off shaft rotational speed
can be
made available with a varying rotational speed of the internal combustion
engine in a
very particularly advantageous manner. Moreover a variable power take-off
shaft
rotational speed can be generated at a generally constant internal combustion
engine
rotational speed.
6 _
CA 02463359 2004-04-07
Thereby two fundamentally different types of attached implements that can be
adapted to a tractor and can be operated with the drive arrangement according
to the
invention to very particular advantage: On the one hand these are operating
implements that require a constant input rotational speed, for example, mower
heads
or non-self propelled rotobalers. On the other hand these are operating
implements
that require an input rotational speed that varies as a function of the
tractor velocity or
the path covered. Examples of the latter are sowing machines.
In order to provide an efficient control of the drive arrangement according to
the invention the data of the condition of the internal combustion engine, the
power
take-off shaft, of the electrical machine and/or the further electrical
machine can be
detected by the ~ntrol arrangement. The data of the condition are preferably
detected by sensors. The data of the condition of the internal combustion
engine are
usually known to a control arrangement of the internal combustion engine and
accordingly need only be transmitted to the control arrangement of the drive
arrangement. The data of the condition of the power take-off shaft can be
detected by
means of a rotational speed sensor an-anged on the power take-off shaft, and
transmitted to the control arrangement. The data of the condition of the
electrical
machines can be detected by means of a current or voltage measurement and
transmitted to the control arrangement. Thereby a control circuit can be
attained for
the adjustment of the power take-off shaft rotational speed together with the
sensors
and the control arrangements.
Very generally when the brake is released the electrical machine, the further
electrical machine and the combination gearbox can be combined into an
infinitely
variable torque division gearbox for the power take-off shaft. As already
indicated
thereby the further electrical machine can be operated as generator and the
electrical
machine as electric motor. Alternatively the electrical machine can also be
operated
as generator and the further electrical machine operated as electric motor,
where in
this case a mechanical feedback over the electric line occurs.
7 _.
CA 02463359 2004-04-07
Now on the basis of the invention on the one hand a required constant
rotational speed of the power take-off shaft can be made available on the
basis of the
drive arrangement according to the invention even with an internal combustion
engine
operated with variable rotational speed. On the other hand with the drive
arrangement according to the invention even with a constant rotational speed
of the
internal combustion engine a variable speed of the power take-off shaft can be
made
available. Therefore it is conceivable that the control arrangement controls
the
electrical machine and the further electrical machine in such a way that an
optimization
goal deposited in memory can be attained. Such an optimization goal could be,
for
example, the lowest possible fuel consumption of the internal combustion
engine or
the lowest possible noise emission.
Now an operating implement connected to the power take-off shaft can briefly
develop torque peaks and produce torsional vibrations that are transmitted by
the
power take-off shaft to the internal combustion engine over the combination
gearbox.
This results in jerk-like or periodic loads on the internal combustion engine,
that impair
the operating comfort. To avoid the transmission of torsional vibrations over
the
combination gearbox to the power take-off shaft, in a particularly preferred
embodiment, the control arrangement, the electrical machine and/or, if
necessary, the
further electrical machine are controlled in such a way that torsional
vibrations in a
power take-off shaft driveline can be damped. In this connection the power
take-off
shaft driveline is understood to include the components arranged between the
power
take-off shaft and the internal combustion engine, such as, for example, the
combination gearbox, the electrical machine and the further electrical
machine. On
the basis of this control arrangement the electrical machine and/or the
further electrical
machine absorbs torsional vibrations or damps these, so that a transmission of
torsional vibrations to the internal combustion engine is largely avoided.
In actual fact the transmission of the combination gearbox could be designed
in such a way that the rotational speeds required in the principal operating
region of
the power take-off shaft lie in regions of optimum efficiency of the internal
combustion
8
CA 02463359 2004-04-07
engine. Preferably the transmission of the combination gearbox could also be
designed in such a way that a minimum power proportion of the electrical
and/or the
further electrical machine must be made available. Thereby electrical losses
can be
minimized to great advantage and the entire system can be operated at optimum
efficiency.
With the drive arrangement according to the invention a determination of the
torque of the power take-off shaft is possible to particular advantage without
the cost
of further configurations by the use of the torque generated by the electrical
machine
for this determination. Since the characteristics of the combination gearbox -
in
particular its gear ratio - are known and the torque transmitted to the
electrical
machine can easily be determined - for example, by a current rrieasurement -
the
torque transmitted to the power take-off shaft can be determined directly. The
determination of the torque of the power take-off shaft is possible,
independently of the
question whether the electrical machine operates as generator or as motor.
In a preferred embodiment the electrical machine and the further electrical
machine are arranged close by each other in space. Thereby a compact and space-
saving arrangement can be achieved and the electrical cables can be held as
short as
possible. Preferably both electrical machines can be cooled by a common
cooling
arrangement. Thereby only a correspondingly configured cooler body is
required, that
coots the two electrical machines arranged close to each other. Thereby
because of a
compact arrangement a separate cooler body for the second machine can be
omitted.
Hence the coolant lines need be conducted only to this single cooler body,
which
further simplifies the entire cooling system and reduces its cost.
Now the electrical machine andlor the further electrical machine can each
operate as generator and supply an electrical device. In this way, for
example, an
electric resistance heater could be operated, that heats a coolant circuit of
the internal
combustion engine whereby, for example, the cooling circuit of the internal
combustion
engine could, for example, be brought to its operating temperature more
rapidly shortly
9
CA 02463359 2004-04-07
after starting. Moreover an electrical device that can be connected to an
electrical
interface could be supplied. The electrical interface could include, for
example, a
receptacle that makes 220 volt alternating current available.
The drive arrangement according to the invention could be implemented in a
particularly preferred embodiment in a vehicle, particularly in an
agricultural or an
industrial utility vehicle.
In such a vehicle a control of the rotational speed of a power take-off shaft
could be provided that is a function of the vehicle speed. Such a "path power
take-off
shaft" is provided particularly for tractors for the adaptation of operating
implements
that require an input rotational speed that is a function of the vehicle
speed, for
example, a sowing machine.
In a preferred embodiment the electrical machine and/or the further electrical
machine can be configured for the braking of the vehicle, particularly for
long duration
braking. In that way, for example, the electrical power generated by both
electrical
machines could be conducted to an electrical resistance heater. In particular
during
extended downhill operation a long duration braking arrangement without wear
for the
vehicle could be made available that finally improves the safety and
reliability of the
vehicle.
In a very particularly preferred embodiment the vehicle is provided with at
least one vehicle wheel driven by an electric motor, and the electrical energy
generated by an electrical machine operating in generator operation feeds the
electric
motor of the vehicle wheel. For example, the vehicle wheels of the front axle
could be
driven electrically, while the internal combustion engine - if necessary
drives the
wheels of the rear axle over an intervening gearbox. Here, to a very
particular
advantage, the rotational speed of the electrically driven wheels of the front
axle of the
vehicle can be infinitely variable, provided that a sufficient amount of
electrical energy
is available.
..--
CA 02463359 2004-04-07
Fundamentally during the pure vehicle operation the power take-off shaft
could be stopped with the brake. This is the case particularly when no
attached
implement is adapted to the vehicle that is configured, for example, as a
tractor and a
power take-off shaft operation is not needed. When the brake is stopped the
mechanical energy supplied by the internal combustion engine into the
combination
gearbox is converted almost without any losses by means of the electrical
machine
that can be operated as generator.
In general, the present invention concerns a drive arrangement for the drive
of attached implements for a vehicle, particularly an agricultural or
industrial utility
vehicle, with a combination gearbox, an electrical machine and a power take-
off shaft,
where a gearbox interface of the combination gearbox can be driven by an
internal
combustion engine and where the electrical machine is connected with a second
gearbox interface of the combination gearbox. In order to make available a
variable
power take-off shaft rotational speed that is independent of the rotational
speed of the
internal combustion engine, the drive arrangement according to the invention
is
characterized by the fact that the power take-off shaft is connected with a
third
gearbox interface of the combination gearbox. Furthermore the present
invention
concerns a vehicle with such a drive arrangement.
To acquaint persons skilled in the art most closely related to the present
invention, one preferred embodiment of the invention that illustrates the best
mode
now contemplated for putting the invention into practice is described herein
by and
with reference to, the annexed drawings that form a part of the spec~cation.
The
exemplary embodiment is described in detail without attempting to show all of
the
various forms and modifications in which the invention might be embodied. As
such,
the embodiment shown and described herein is illustrative, and as will become
apparent to those skilled in the art, can be modified in numerous ways within
the
spirit and scope of the invention--the invention being measured by the
appended
claims and not by the details of the specification.
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Brief Description of the Drawin4s
For a complete understanding of the objects, techniques, and structure of
the invention reference should be made to the following detailed description
and
accompanying drawings, wherein:
Fig. 1 is a schematic representation of the first embodiment of the present
invention.
Fig. 2 is a schematic representation of a second embodiment of the present
invention;
Fig. 3 is a schematic representation of an embodiment of a combination
gearbox according to the present invention; and,
Fig. 4 is a schematic representation of a further development of the first
embodiment of the present invention.
Descrio~ion of the Preferred Embodiment
Figure 1 shows a drive arrangement for the drive of attached implements for a
vehicle. Such a vehicle may, for example, be an agricultural or industrial
utility vehicle,
preferably this could be a tractor. An internal combustion engine 18 is
connected with
a combination gearbox 10 over a drive shaft 38. The combination gearbox 10 is
connected to a power take-off shaft 14 with which attached implements for the
vehicle
can be driven. An electrical machine 12 is also connected to the combination
gearbox
10. Thereby the drive arrangement includes a combination gearbox 10, an
electrical
machine 12 and a power take-off shaft 14.
The internal combustion engine 18 drives a Diesel engine a gearbox interface
16 of the combination gearbox 10 in particular. The electrical machine 12 is
connected with a second gearbox interface 20 of the combination gearbox 10.
The
power take-off shaft 14 is connected with a third gearbox interface 22 of the
combination gearbox 10. Due to this arrangement the rotational speed of the
power
12 i
CA 02463359 2004-04-07
take-off shaft can be controlled independently of the rotational speed of the
internal
combustion engine 18, in that the electrical machine 12 is driven, for
example, as an
electric motor and transmits the torque generated by it to the combination
gearbox 10.
A brake 24 is provided with which the ewer take-off shaft 14 can be stopped.
When the power take-off shaft 14 is stopped the torque delivered to the
gearbox
interface 16 by the internal combustion engine 18 is transmitted over the
combination
gearbox 10 to the electrical machine 12, which, for its part, is then operated
as
generator and generates electrical current. In so far by corresponding
switching of the
electrical machine 12 and by a simple measure, that is, the stopping of the
brake,
electrical current can be generated that can be made available to electrical
devices.
A further electrical machine 36 is provided that is driven by the internal
combustion engine 18 directly over the shaft 38. The further electrical
machine 36
preferably has a rated power output of approximately 20 kW. The rated power
output
of the electrical machine 12 amounts to approximately 30 kW, that of the
internal
combustion engine 18 preferably approximately 100 kW.
Both the electrical machine 12 as well as the further electrical machine 36
can
be operated as generator. Furthermore the electrical machine 12 or the further
electrical machine 36 can be operated as electric motor.
Each of the electrical machine 12 and the electrical machine 36 is associated
with a rectifier 40, with which each of the electrical machines 12, 36 can be
switched in
both directions of rotation and/or directions of torque, so that a four-
quadrant operation
of the electrical machines 12, 36 is possible.
A control arrangement 42 is provided that controls the internal combustion
engine 18, the electrical machine 12, the further electrical machine 36, the
rectifiers 40
and the brake 24. The control arrangement 42 can be connected with the
individual
components over a bus system of the vehicle, which is indicated by the
elongated
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CA 02463359 2004-04-07
shape of the control an-angement 42 in figure 1.
The data of the condition of the internal combustion engine 18, the power
take-off shaft 14, the electrical machine 12 and the further electrical
machine 36 can
be detected by the control arrangement 42. For this purpose, for example, a
rotational
speed sensor 46 is provided on the power take-off shaft 14, which generates a
rotational speed signal and conducts it to the control arrangement 42 over the
connecting line 48. The data of the condition of the internal combustion
engine 18 are
known to the control arrangement 50 of the internal combustion engine 18 and
are
conducted to the control arrangement 42 over the connecting line 52.
Furthermore a
rotational speed sensor 49 is provided that detects the rotational speed of
the engine
output shaft 38, generates a rotational speed signal and conducts it to the
control
arrangement 42 over the connecting line 51. The data of the condition of the
two
electrical machines 12, 36 are known to the control arrangement 42 on the
basis of the
electrical data of the magnitude of the condition generated by the rectifiers
40 that are
connected to the control arrangement 42 over the connecting line 54. In
addition a
rotational speed sensor 44 is provided that detects the rotational speed and
direction
of rotation of the second gearbox interface 20 and thereby the rotational
speed and
direction of rotation of the ehectrical machine 12 and reports it to the
control
arrangement 42. The rotational speed sensor 44 is connected with the control
arrangement 42 over the connecting line 45.
During power take-off shaft operation, that is with the brake 24 released, the
electrical machine 12, the further electrical machine 36 and the combination
gearbox
can be combined to an infinitely variable torque division gearbox for the
power
take-off shaft 14. Here the further electrical machine 36 is preferably
operated as
generator and the electrical machine 12 operated as an electric motor.
The brake 24 is operated by an electric control element 56. The current
supply for this is provided to the electrical control element 56 from a direct
current
network 58 into which the electrical machine 12, 36 also supply the electrical
energy
14
CA 02463359 2004-04-07
they generate or from which the electrical machines 12, 36 are also supplied
with
electrical energy, depending on the question whether they are operated as
generator
or as electric motor. The electrical control element 56 is controlled by the
control
arrangement 42 over the connecting line 60.
The electrical machine 12 can operate as generator and thereby supply an
electric device, for example, an electric device, not shown, that can be
connected to
an electric interface 63. The electrical interface 63 could be configured, for
example,
in the form of a receptacle. The interface 63 is supplied with electrical
energy by a
control arrangement 65 over the connecting line 67. This interface makes
alternating
current available to the supply which is generated by the direct current
derived from
the direct current network 58 by a rectifier, not shown separately, associated
with the
control arrangement 65. By the same token an electrical device can be
connected to
the electrical interface 73 configured in the form of a receptacle, that makes
available
direct current to the electrical device directly from the direct current
network 58.
Alternatively the electrical energy generated by the electric machine 12 can
be
conducted to a resistance brake 69 which converts it into heat. For this
purpose a
switch 71 is switched by the control arrangement 42 in order to connect the
resistance
brake 69 with the direct current network 58.
The embodiment shown in figure 2 shows a drive arrangement according to
the invention, that is installed in an agricultural utility vehicle. In
figures 1 and 2 the
same components are identified by the same part number call-outs.
The vehicle is provided with two vehicle wheels 66 each of which is driven by
an electric motor 64. The vehicle wheels 66 are vehicle wheels of a front axle
of the
vehicle. The electrical energy required by both motors 64 is generated either
by the
electrical machine 12 or by the further electrical machine 36 and is made
available to
the electric motors 64 over the direct current network 58 over the rectifiers
40. The
rectifier 40 associated with the electric motors 64 are connected to the
control
arrangement 42 over the connecting lines 72. In place of the two electric
motors 64 a
CA 02463359 2004-04-07
single electric motor could also be provided, that drives both vehicle wheels
of the
front axle. Moreover vehicle wheels 68 of a rear axle of the vehicle are
provided, that
are connected with the internal combustion engine over a gearbox 70.
Besides the rotational speed sensor 46 for the power take-off shaft 14, four
further rotational speed sensors 74 are provided each of which detects the
rotational
speed of the vehicle wheels 66 or 68. A rotational speed sensor 76 detects the
rotational speed of the engine output shaft 38 and thereby the rotational
speed of the
internal combustion engine 18. The connecting lines 78 or 80 connect the
rotational
speed sensors 74 or 76 with the control arrangement 42.
In figure 2 the electrical machine 12 and the further electrical machine 36
are
arranged side by side close to each other. Thereby both electrical machines
12, 36
can be cooled by a single cooling arrangement 62 - indicated only
schematically.
Figure 3 shows an embodiment of a combination gearbox 10 of the present
invention. The combination gearbox 10 is configured as a planetary gearbox.
The
planetary gearbox includes an internal gear 26, that is driven by an internal
combustion engine - not shown in frgure 3 - over the gearbox interface 16. The
sun
gear 28 of the planetary gearbox is connected with the electrical machine -
also not
shown in figure 3. The power take-off shaft - not shown in figure 3 -is
connected to
the planet carrier 30, where preferably three sets of planet gears 32, 34 are
arranged
on the planet carrier 30, each of which is provided with two planet gears with
different
diameters. The planet gears 32 with the smaller diameter mesh with the sun
gear 28
and the planet gears 34 with the larger diameter mesh with the internal gear
26.
If the gear pitch diameters of the internal gear 26 to the gears 32 of smaller
diameter to the gear 34 of larger diameter and to the sun gear 28 are in a
proportion to
each other of 27 to 6 to 9 to 12 with respect to the internal gear 26, then at
a rotational
speed of the internal combustion engine of +2000 revolutions per minute and
with the
brake 24 applied, that is, with the power take-off shaft stopped, the
electrical machine
16
CA 02463359 2004-04-07
is driven at a rotational speed of -3000 revolutions per minute. Therefore the
electrical
machine 12 is provided with a step up speed ratio relative to the internal
combustion
engine 18 which results in a favorable power delivery of the electrical
machine 12,
when it is operating as a generator.
On the other hand during power take-off shaft operation, that is, when the
brake 24 is released, a power take-off shaft speed of 1000 revolutions per
minute
could be demanded. With a rotational speed of the internal combustion engine
18 of
+2000 revolutions per minute a resulting rotational speed of the electrical
machine 12
of -500 revolutions per minute is required.
Therefore the transmission of the combination gearbox 10 is designed in such
a way that the rotational speeds required in the principal operating region of
the power
take-off shaft 14 lie in the region of optimum efficiency of the internal
combustion
engine 18 and that a comparably smaller proportion of power of the electrical
machine
12 must be made available.
Figure 4 shows a further development of the first embodiment according to
figure 1, that is provided with a spur gear stage 82 which can be shifted. A
shaft 84 is
provided between the spur gear stage 82 and the third gearbox interface 22,
which
transmits the torque made available by the third gearbox interface 22 to the
spur gear
stage 82 that can be shifted. The spur gear stage 82 that can be shifted
includes two
spur gears 86 connected to the shaft 84, where the spur gear 86 shown at left
is
provided with a larger diameter compared to the spur gear 86 shown at right.
Each of
the spur gears 86 mesh with a shifted spur gear 88, where the spur gear 88
shown at
left is provided with a smaller diameter than the spur gear 88 shown at right.
The shifted spur gears 88 can be shifted in corresponding manner by a
control arrangement 90, so that the torque transmitted by the shaft 84 is
transmitted to
the power take-off shaft 14 either over the two spur gears 86, 88 shown at
left or the
two spur gears 86, 88 shown at right. The control arrangement 90 is controlled
by the
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CA 02463359 2004-04-07
control arrangement 94 by means of the control arrangement 42 over the
connecting
line 92. The shifted spur gear stage 82 of figure 4 can also be connected with
the
power take-off shaft 14 of the second embodiment according to figure 2.
Thus it can be seen that the objects of the invention have been satisfied by
the structure presented above. While in accordance with the patent statutes,
only
the best mode and preferred embodiment of the invention has been presented and
described in detail, it is not intended to be exhaustive or to limit the
invention to the
precise form disclosed. Obvious modifications or variations are possible in
light of
the above teachings. The embodiment was chosen and described to provide the
best illustration of the principles of the invention and its practical
application to
thereby enable one of ordinary skill in the art to utilize the invention in
various
embodiments and with various modifications as are suited to the particular use
contemplated. All such modifications and variations are within the scope of
the
invention as determined by the appended claims when interpreted in accordance
with the breadth to which they are fairly and legally entitled.
18
