Selectively connectable engine for a vehicle having an electric drive motor

A drive device has the following components: a connecting device that can be connected to an electric power supply, the connecting device being connected to a power converter; a first drive aggregate in the form of an electrical drive motor which is connected to the power converter; a second drive aggregate in the form of an internal combustion engine; a generator connected to the internal combustion engine and through the power converter to the electric drive motor; and various auxiliary aggregates. The generator is continuously mechanically connected to the respective auxiliary aggregates while the internal combustion engine is optionally connectable to the auxiliary aggregates as well as to the generator. In a first mode of operation, upon operation of the electric drive motor through the external electric power supply, the generator is separated from the internal combustion engine and the generator, supplied by the power supply, is operated as an electric motor and drives the auxiliary aggregates. In a second mode of operation, upon operation of the electric motor through the internal combustion engine, the internal combustion engine is designed in such a way that it drives the generator and the auxiliary aggregates.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a drive device for a means of transportation, 
particularly a trolley bus or rail vehicle. 
2. Description of Related Technology 
Drive devices for means of transportation, i.e., vehicles, such as trolley 
buses or rail vehicles, may include an electrical connection device that 
can be connected to an external electrical power source. The connection 
device is also connected to a (static) power converter. Such a drive 
device may further include: a first drive aggregate in the form of an 
electrical drive motor connected to the power converter; a second drive 
aggregate in the form of an internal combustion engine; a generator 
connectable to the internal combustion engine and alternatively 
connectable via the power converter to the electrical drive motor; and at 
least one auxiliary aggregate for the vehicle. 
Such drive devices are being used in buses, especially in trolley buses or 
double-decker buses. However, they could also be used in rail vehicles. 
Such drive devices have the advantage that, in normal operation, the 
driving of the vehicle is performed via the electrical drive motor. Thus, 
especially in city traffic, i.e., in highly populated areas, the emission 
of waste gases and harmful substances is avoided. 
The purpose of the addition of an internal combustion engine is to increase 
the radius of action of the vehicle, because, for example, an overhead 
trolley system is built only in the central area of the city, and 
therefore, in the outskirts of the city or on branch lines (detours) 
another drive aggregate is required. 
On the other hand, such internal combustion engines can be used as a second 
drive aggregate in order to drive the vehicle when breakdowns occur in the 
external electrical supply network so that the operation of the vehicle 
can be maintained without disturbance. 
In conventional buses (city buses as well as country buses), a number of 
additional auxiliary aggregates are required, for example, a water pump, 
an air compressor, and a power-steering pump for power steering. The 
auxiliary aggregates are driven by the internal combustion engine through 
one or more V-belts. The internal combustion engines of such conventional 
buses are designed for this additional power output and the required space 
for these auxiliary aggregates is available in the vehicle. 
However, in trolley buses, such a direct drive of the auxiliary aggregates 
by the internal combustion engine is usually not possible. The problem 
arises that the auxiliary aggregates that are connected to the internal 
combustion engine are no longer driven when, for example in city 
operation, the drive is performed exclusively electrically, i.e., by the 
external electrical power supply via the electrical drive motor. 
In combined drive devices of the type described herein, therefore, a 
separate dc on-board system has been installed, for example, with 24 volt 
dc voltage on the board of a trolley bus, this on-board system being 
connectable to the external electrical power supply through suitable 
transformers. Then a number of separate electric motors are connected to 
this on-board system, each of which drives an auxiliary aggregate. If the 
driving of the vehicle is performed via the internal combustion engine, 
for example, if there is trouble in the external electrical power supply, 
the internal combustion engine also drives an emergency power supply which 
supplies the on-board system with electrical energy. 
It appears that such a design of a drive device with a plurality of 
parallel and separate auxiliary aggregates, each with their own electric 
motor and corresponding controls is very expensive and complicated and, 
moreover, requires significant space. Apart from the considerable cost 
that arises from the plurality of electric motors and controls, another 
disadvantage of such a design is the poor degree of cooperation of the 
drive device arrangement with these additional electrical drive devices. 
SUMMARY OF THE INVENTION 
It is an object of the invention to overcome one or more of the problems 
described above. It is also an object of the invention to provide a drive 
device of the type described herein which has a simplified construction of 
auxiliary aggregates and cooperating drives as well as to make it possible 
to place the auxiliary aggregates into a smaller space without adversely 
influencing the reliability of such components. 
According to the invention, a drive device for a vehicle includes an 
electrical connecting device connected to a power converter and 
connectable to an electrical power supply, a first drive aggregate in the 
form of an electric drive motor connected to the power converter, a second 
drive aggregate in the form of an internal combustion engine, a generator 
connectable to the internal combustion engine and connectable through the 
power converter to the electric drive motor, and at least one auxiliary 
aggregate for the vehicle. Also according to the invention, the generator 
is constantly mechanically connected to the auxiliary aggregate while the 
internal combustion engine is optionally connected to the auxiliary 
aggregate as well as to the generator. Thus, in a first mode of operation 
of the electrical drive motor through the external electrical power 
supply, the generator is separated from the internal combustion engine and 
via the external electrical power supply, the generator is operated as an 
electric motor, driving the auxiliary aggregate. In a second mode of 
operation of the electric drive motor through the internal combustion 
engine, the internal combustion engine drives both the generator and the 
auxiliary aggregate. 
Other objects and advantages of the invention will be apparent to those 
skilled in the art from the following detailed description taken in 
conjunction with the drawings and the appended claims.

DETAILED DESCRIPTION OF THE INVENTION 
According to the invention, a drive device has been designed so that a 
generator thereof is constantly mechanically connected with respective 
auxiliary aggregates, while an internal combustion engine can be connected 
to the auxiliary aggregates as well as to the generator. Thus, on the one 
hand, during operation of an electrical drive motor by an external 
electrical supply, the generator is separated (i.e. disconnected) from the 
internal combustion engine, and the generator, which is supplied by the 
external electrical power source, is driven as an electric motor and 
drives the auxiliary aggregates. On the other hand, when the electrical 
drive motor is operated via the internal combustion engine, the internal 
combustion engine drives both the generator and the auxiliary aggregates. 
In this way, an object of the invention is satisfactorily provided. 
Separate electric motors with their corresponding controls are not 
required for the particular auxiliary aggregates. As a result of this, the 
cost of the vehicle is reduced and the space requirement is also reduced. 
Since a power converter for the electrical drive motor which has 
corresponding power electronics is present anyway, this component is 
utilized for driving all of the auxiliary aggregates so that no additional 
components are necessary. 
In a further embodiment of a drive device according to the invention, a 
switchable connection between the internal combustion engine on the one 
hand and the particular auxiliary aggregate on the other hand, has a 
meshable clutch coupling. Thus, it is possible to connect the respective 
auxiliary aggregates to the internal combustion engine as a drive 
aggregate by mechanical means. 
Another feature of a drive device according to the invention is that a gear 
box is provided as a mechanical connection between the internal combustion 
engine, generator and the respective auxiliary aggregates. In this way, 
suitable mechanical connection is ensured which takes into consideration 
the requirements of the particular auxiliary aggregates. 
Preferably, several auxiliary aggregates can be connected simultaneously to 
the generator or optionally to the internal combustion engine. 
While the internal combustion engine utilized in the inventive device can 
be a diesel engine such as those utilized in many types of vehicles, both 
the generator and the electrical drive motor are preferably designed as 
transverse-flow machines. Advantageously, the high efficiency of 
transverse-flow machines can be utilized 90% to 95%. Such transverse-flow 
machines are known and described, for example, in DE 39 27 453. 
In drive devices according to the invention, the internal combustion engine 
on the one hand and the generator on the other hand are preferably 
components of an emergency power aggregate or of an alternative or 
additional power supply for the electrical drive motor. This design makes 
it possible to ensure driving of the auxiliary aggregates in all cases 
independently of a disturbance or even failure of the external electrical 
power supply. 
In a further embodiment of a drive device according to the invention, the 
generator and the electrical drive motor are connectable through a power 
converter to a trolley system or a live rail as an electrical power 
supply. 
In a preferred embodiment of a drive device according to the invention, the 
auxiliary aggregates have a steering booster pump, an air compressor, an 
on-board power generator and/or a water pump. However, additional or other 
auxiliary aggregates can be provided, for example, heating or cooling 
aggregates. 
In a further embodiment of a drive device according to the invention, the 
generator can be operated as a starter for the internal combustion engine. 
In this way, a protected, but reliable starting of the internal combustion 
engine is provided. Namely, the starting is done at high rpm, so that 
particle exhaust is reduced in the case of diesel engines. 
In addition to the advantages already described herein there are a number 
of other advantages of a device according to the invention. For example, 
the total efficiency can be increased, because the on-board system in the 
drive device according to the invention has an especially high efficiency. 
On the one hand, an on-board system transformer between the external 
electrical power supply and the on-board system, as well as the 
corresponding electric motors, can be omitted, which otherwise bring about 
relatively high electrical losses. On the other hand, the power 
requirement from such an on-board system can be reduced, which is 
manifested in a reduced space requirement and lower costs for the on-board 
system. 
Since the on-board voltage generator as an auxiliary aggregate is driven 
either by the generator or the internal combustion engine, an on-board 
power transformer can be omitted, which saves even more space. At the same 
time, the expenditure for the insulation of the on-board system is reduced 
because protective insulation (double insulation) against the external 
electrical power supply is no longer necessary, since, in case of any 
damage, no galvanic connection can occur to the external electrical power 
supply, for example, to a trolley system. 
With reference to the drawings, FIG. 1 is a schematic diagram showing a 
first mode of operation of a drive device according to the invention 
wherein a vehicle (not shown), for example, a trolley bus, is driven by an 
electric drive motor 20 through a drive pinion 26. 
In the first mode of operation shown in FIG. 1, the electrical drive motor 
20 is connected via a schematically indicated line 24 to a power converter 
21, which is preferably designed as an invertor. The power converter 21 
can be connected through an electrical connecting device 22, for example, 
a horizontal draw-out current collector on the roof of a trolley bus, to a 
trolley line as an external electrical power supply 23. 
The power converter 21 is connected to a generator 3 through another line 
25. The generator 3 is preferably a transverse-flow machine which can be 
driven optionally as a generator or as an electric motor. Preferably, the 
generator 3 is designed in such a way that it can be operated as a starter 
for an internal combustion engine 2, with a control (not shown). 
A gear box 1 is disposed between the generator 3 and the internal 
combustion engine 2, which is preferably a diesel engine. The gear box 1 
has a first shaft 4 connected to the internal combustion engine 2 and a 
second shaft 5 connected to the generator 3. At least one gear 7 is 
mounted on the shaft 5, which is engaged to another gear 9 in order to 
transfer torque to a corresponding auxiliary aggregate 10. 
FIG. 1 shows other auxiliary aggregates 11 and 12, which can be connected 
in a corresponding manner to the shaft 5, either through corresponding 
additional gears 7 on the shaft 5 with gears which are not shown, that 
correspond to the gear 9, or through corresponding gears which are engaged 
with the gear 9 or the gear 7. 
The gear box 1 has a meshable clutch coupling 6 disposed between the shafts 
4 and 5, shown in FIG. 1 in an out-of-gear position. 
The power flow is indicated schematically in FIG. 1 with the aid of arrows. 
It can be seen that energy is supplied primarily from the external 
electrical power supply 23 through the electrical connection device 22 to 
the power converter 21. From there, in a first branch (indicated by the 
arrow "a"), the electrical drive motor 20 is supplied with energy and is 
driven. In a second branch (indicated by the arrows "b"), the energy 
supply goes to the generator 3 through the line 25. In this type of 
operation, the generator operates as a drive motor and drives the various 
drive aggregates 10, 11, 12 through the shaft 5. In this type of 
operation, the internal combustion engine 2 is not connected (i.e. does 
not supply energy) to the remainder of the device. 
FIG. 2 shows a second mode of operation of the inventive drive device. It 
can be seen that the electrical connecting device 22 is separated from the 
external electrical power supply 23. In this case, the meshable clutch 
coupling 6 is put into gear in the gear box 1 so that the internal 
combustion engine 2 is connected mechanically both to the auxiliary 
aggregates 10, 11 and 12 as well as to the generator 3. 
Here, too, the power flow is indicated with arrows. In a first branch 
(indicated by the arrows "c"), the internal combustion engine 2 drives the 
auxiliary aggregates 10, 11 and 12 through the shaft 4, the in-gear clutch 
coupling 6 and the gear 7. In a second branch (indicated by the arrows 
"d"), the internal combustion engine 2 drives the generator 3 through the 
shaft 4, the in-gear clutch coupling 6 and the other shaft 5. The 
generator 3 now produces the required electrical energy (flow indicated by 
the arrows "e") to supply the electrical drive motor 20 with current 
through the line 25, the power converter 21 and the line 24, and to drive 
it in this way. 
FIG. 3 shows the details of an embodiment of a gear box 1 according to the 
invention which can be connected on a left side thereof to the internal 
combustion engine 2 and on the right side thereof to the generator 3. 
In a housing 15 having a plurality of carriers 17, the first shaft 4 and 
the second shaft 5 are rotatably supported via suitable bearings; the 
first shaft 4 is connected to the internal combustion engine 2 (not shown 
in FIG. 3), while the second shaft 5 is connected through a coupling 18 to 
the generator 3 (not shown in FIG. 3). 
The shaft 4 is provided with the meshable clutch coupling 6 on an end 
thereof disposed away from the internal combustion engine 2, this coupling 
having an outer ring 19, which can be brought to engagement with a 
coupling tappet 14 of the shaft 5 when the clutch coupling 6 is in gear. 
The first gear 7 is seated on the shaft 5 and meshes with another gear 9 on 
the shaft 8 and serves to drive the auxiliary aggregate 10. For this 
purpose, the shaft 8 of the gear 9 is supported in a corresponding bearing 
16, mounted in carriers shown schematically in FIG. 3. 
The other auxiliary aggregates 11 and 12, shown schematically in FIGS. 1 
and 2, as well as other auxiliary aggregates (not shown) are connected 
correspondingly mechanically with the shaft 5 whereby the corresponding 
gears 9 of these auxiliary aggregates mesh either with one gear 7 or with 
additional gears 7 on the shaft 5. 
The auxiliary aggregates 10, 11, and 12 may include a steering booster pump 
for the power steering of a vehicle, an air presser (air compressor), an 
on-board system generator, a water pump, a heating device and a cooling 
device (air conditioner compressor) for the particular means of 
transportation. The number of connectable auxiliary aggregates are not 
limited in any way and are chosen depending on the practical requirements 
of the vehicle. 
Drive devices according to the invention as described herein satisfy 
practical vehicle operating requirements to a full extent and, at the same 
time, are reliable and space-saving. Whether or not energy is obtained 
from external electrical power sources, reliable operation of all drive 
aggregates is ensured. 
The use of transverse-flow machines for the generator 3 and the electric 
drive motor 20 makes it possible to have a design with high efficiency 
achieved with a smaller number of components. 
When the generator 3 is equipped with an energy saver, which is not shown 
here, the generator 3 can be used as a drive motor so that even if the 
external electrical power supply is shut down, it can serve as a starter 
for the internal combustion engine 2. In this way, an additional starter 
can be omitted. 
Even when the generator 3 is still connected through the power converter 21 
and the electrical connecting device 22 to the external electrical power 
supply 23, the generator 3 can still work as a starter for the internal 
combustion engine 2. This may be expedient in situations in which the 
supply voltage in the external electrical power supply fluctuates greatly 
so that a decision is made to use the internal combustion engine 2. Also, 
in situations in which the edge region of a trolley network system is 
reached (i.e., a city boundary), the energy of the external electrical 
power supply 23 can be utilized to start the internal combustion engine 2 
through the generator 3. 
In another embodiment of a device according to the invention not shown in 
the drawings, the drive device can also be connected to an internal 
electrical power supply, for example, to a battery, allowing for operation 
in the battery mode. This is preferable, for example, when the vehicle 
passes through a passenger zone where no trolley line is present. Then, 
the internal combustion engine remains turned off and the operation of the 
electrical drive motor and the auxiliary aggregates is ensured through the 
internal electrical power supply from the battery through the power 
converter. 
The foregoing detailed description is given for clearness of understanding 
only, and no unnecessary limitations should be understood therefrom, as 
modifications within the scope of the invention will be apparent to those 
skilled in the art.