fire engine drive train and fire engine

Abstract

Fire engine drive train (1), in particular for an airfield fire engine, comprising a first drive motor (2) which can be connected to at least one drive axle (16, 17) via a drive motor, wherein the first drive motor (2) can also be connected to at least one fire pump (6) via a drive motor, wherein a second drive motor (22) in the form of an electric motor (23) is provided which is connected or can be connected to the at least one drive axle (16, 17) via a drive motor, in parallel to the first drive motor (2), wherein the first drive motor (2) can be connected to the at least one drive axle (16, 17) via an intermediate motor vehicle transmission (3), wherein different transmission ratios between a transmission input and a transmission output can be switched in the motor vehicle transmission (3),and wherein the first drive motor (2) can be connected to or is connected to the at least one fire pump (6) via an intermediate transmission (4), characterized in that the intermediate transmission (4) is integrated between the first drive motor (2) and the motor vehicle transmission (3), and that a drive-side component of the intermediate transmission (4) is rotationally fixed to an output of the first drive motor (2) or to the transmission input of the motor vehicle transmission (3).

Description

[0001] The invention relates to a firefighting vehicle drive train, in particular for an airfield firefighting vehicle, comprising a first drive motor that can be drivenly connected to at least one drive axle, wherein the first drive motor is also connectable or connected to at least one firefighting pump. Furthermore, the invention relates to a firefighting vehicle with the aforementioned firefighting vehicle drive train.

[0002] In the field of firefighting vehicles, airfield firefighting vehicles have the special feature that, after driving to the scene at top speed, they must be able to slowly drive around the object to be extinguished while operating the respective fire pump at maximum power. This operation is often referred to as pump-and-roll operation. In the drive train of the firefighting vehicle, a low drive power must be transferred to one or more drive axles while simultaneously supplying a high power to the fire pump.

[0003] DE 203 05 101 U1 discloses a fire engine drive train in which a prime mover can be connected to several drive axles of a fire engine via an intermediate motor vehicle transmission. A fire pump is also connected to the motor vehicle transmission via a power take-off. In order to simultaneously enable the fire engine to travel slowly while extinguishing and transmitting high power to the fire pump, the prime mover can be connected to the drive axles via a hydrostatic power branch in parallel with the motor vehicle transmission. If the motor vehicle transmission is in neutral, an output speed to the drive axles can be set by controlling the hydrostatic power branch.At the beginning of DE 203 05 101 U1, a system is also described in the state of the art in which two independent drive machines are used, one of which is intended to operate a fire pump and one of which is intended to drive the fire engine.

[0004] US 2018 / 0 222 484 A1 also discloses a fire engine drive train with a first and a second drive motor, wherein the first drive motor can be embodied as an internal combustion engine and the second drive motor as an electric motor. Both drive motors are connected to a drive axle via a transmission. Said transmission also has a drive connection via which a pump can be driven.

[0005] DE 101 59 210 A1 and DE 10 2017 119 256 A1 each disclose a hybrid vehicle drive with an electric motor, an internal combustion engine and a power take-off drive.

[0006] Based on the prior art described above, it is the object of the present invention to provide a fire engine drive train in which at least one drive axle and one fire pump can be supplied with different drive powers, but which at the same time is characterized by a simple structure.

[0007] This object is achieved based on the preamble of claim 1 in conjunction with its characterizing features. The dependent claims that follow each of these claims provide advantageous developments of the invention. A fire engine is also the subject of claim 6.

[0008] According to the invention, a fire engine drive train comprises a first drive motor, which can be drivenly connected to at least one drive axle. Furthermore, the first drive motor can be drivenly connected to at least one fire pump or is permanently drivenly connected to the at least one fire pump. Thus, the fire engine drive train according to the invention provides a first drive motor, which can function as the drive system for a fire engine by coupling the first drive motor to at least one drive axle of the fire engine. Furthermore, at least one fire pump of the fire engine can be operated via the first drive motor, for which purpose the first drive motor is connected to the fire pump.This connection can be a permanent connection between the first drive motor and the fire pump, but is preferably a separable connection so that no power is transferred to the fire pump when the fire pump is not in operation. A separable connection between the first drive motor and the at least one fire pump is particularly preferably implemented via an intermediate separating clutch, which, when closed, drives the fire pump and the first drive motor together. Such a separating clutch can be a dry-running or wet-running friction clutch.

[0009] The invention now encompasses the technical teaching that a second drive motor in the form of an electric motor is provided, which is or can be connected to the at least one drive axle in parallel with the first drive motor. In other words, in addition to the first drive motor, a further, second drive motor is provided, which is designed as an electric motor. This electric motor is coupled to the at least one drive axle in parallel with the first drive motor or can be coupled to the at least one drive axle.

[0010] Such a design of a fire engine drive train has the advantage that, on the one hand, both drive engines can be used to drive the associated fire engine, thus achieving high acceleration in an emergency. This is because, through a parallel drive connection of both drive engines to the at least one drive axle, the power of both drive engines can be transferred to the at least one drive axle. On the other hand, however, operation can also be realized in which the fire pump is driven by the first drive engine, while the fire engine is driven by the electric motor through a drive connection to the at least one drive axle.This allows for a so-called pump-and-roll operation, in which the fire pump is supplied with high power via the first drive motor to generate the greatest possible pumping power, while simultaneously allowing the fire engine to travel slowly by transferring a low drive power from the electric motor to at least one drive axle, so that the fire engine can slowly circle the object to be extinguished while pumping extinguishing agent. The electric motor can be designed with a lower drive power than the first drive motor.

[0011] In contrast, the fire engine drive train of DE 203 05 101 U1 only provides one drive motor, which drives both the fire pump and the fire engine. In order to be able to supply high power to the fire pump while the fire engine is traveling slowly, the drive motor is coupled to the at least one drive axle via a hydrostatic power branch. However, this results in a complex design of the fire engine drive train of DE 203 05 101 U1. The use of two drive motors, one of which is intended solely for driving the at least one drive axle and one for solely operating the fire pump, requires the use of two powerful drive motors, which also increases the manufacturing cost.

[0012] In the fire engine drive train according to the invention, the electric motor essentially functions as an additional drive unit and can be operated at least as an electric motor for this purpose. However, in addition to operating the electric motor as an electric motor, it is particularly preferred that it also be operated as a generator, in order to generate electrical energy via the electric motor in certain driving situations. Thus, the electric motor could be used for braking during the fire engine's braking maneuvers, and thus electrical energy could be generated via it through recuperation.

[0013] The fact that the electric machine is connected “parallel” to the first drive machine with the at least one drive axle or can be connected thereto means, within the meaning of the invention, that the electric machine can transmit drive power to the at least one drive axle of the fire engine independently of the first drive machine. This power flow can take place completely independently of a power flow which is guided via the first drive machine to the at least one drive axle, in that the drive power of the electric machine is guided to the at least one drive axle via different components of the fire engine drive train than occurs when drive power is guided by the first drive machine. However, in order to keep the number of components low, some of the same components are preferably used in the fire engine drive train.In this case, with a common drive via the first drive motor and the electric motor, the power flows are combined at one component in the drive train, from which a further common supply to the at least one drive axle then takes place.

[0014] According to the invention, the first drive motor can be connected to the at least one drive axle via an intermediate motor vehicle transmission. Different gear ratios can be switched between a transmission input and a transmission output in the motor vehicle transmission. In this case, a drive movement of the first drive motor to be transmitted to the at least one drive axle is transmitted via a downstream motor vehicle transmission having multiple gear ratios. This motor vehicle transmission can, in principle, be a manual transmission, an automated transmission, an automatic transmission, or even a continuously variable transmission.In addition, the motor vehicle transmission can be a single transmission or a transmission with a group design, in which several different transmission groups, such as a splitter group, a main group and / or a range group, are arranged between the transmission input and the transmission output. A starting element can also be provided between the first drive motor and the transmission input of the motor vehicle transmission, for example in the form of a dry-running or wet-running friction clutch or even a hydrodynamic torque converter. Advantageously, this allows a drive movement of the first drive motor to be translated to the at least one drive axle, establishing suitable driving ranges. In addition, the power transmission from the first drive motor to the at least one drive axle can be interrupted by switching to neutral in the motor vehicle transmission.

[0015] According to the invention, the first drive motor is drivingly connected to the at least one fire pump via an intermediate gearing or can be connected to the at least one fire pump via the intermediate gearing. By using an intermediate gearing, a suitable drive movement for operating the fire pump can be easily realized. The intermediate gearing can be formed by one or more spur gear and / or planetary gear stages.

[0016] In the inventive combination of the two aforementioned variants, the intermediate gear ratio is integrated between the first drive motor and the motor vehicle transmission. This ensures that, when the motor vehicle transmission is in neutral, the fire pump can still be driven by the first drive motor. A drive-side component of the intermediate gear ratio, such as a spur gear, is rotationally fixedly connected to an output of the first drive motor or the transmission input of the motor vehicle transmission.

[0017] According to a further embodiment of the invention, the first drive motor is designed as an internal combustion engine. This has the advantage that suitable drive power can be provided for driving the fire engine and also for operating the at least one fire pump. Alternatively, it is also conceivable within the scope of the invention to also design the first drive motor as an electric motor. In the case of the internal combustion engine design, the first drive motor is preferably connected to the downstream components in the fire engine drive train via a starting element.

[0018] In a further development of the invention, a plurality of drive axles are provided which are connected to a transfer case. In this case, the associated fire engine therefore has at least two, but possibly even three or four drive axles. If there are more than two drive axles, one or more further transfer cases are then coupled to the transfer case for distribution to the further drive axles within the scope of the invention. The transfer case preferably also has a first transmission input which serves to connect to the first drive motor, and a second transmission input which is provided for connection to the second drive motor. In this case, the power flows of the first drive motor and the electric motor are combined in the area of ​​the transfer case, via which the power is then distributed to the plurality of drive axles.For this purpose, the transfer case is equipped with two transmission inputs and two transmission outputs.

[0019] According to one embodiment of the invention, the electric machine can be connected to the at least one drive axle via an intermediate transmission. Different transmission ratios can be switched in the transmission. This also makes it possible, in the case of the electric machine, to translate a drive movement generated by the electric machine in a suitable manner using different gears of the downstream transmission. Furthermore, the electric machine could also be separated from the rest of the drive train by switching the transmission to neutral. Alternatively, the electric machine could also be coupled or coupleable to the at least one drive axle with a fixed transmission ratio. A transmission ratio of 4.6 is particularly preferred. In both cases, it would also be conceivable to provide a separating clutch between the electric machine and the transmission.

[0020] The invention also relates to a firefighting vehicle having a firefighting vehicle drive train configured according to one or more of the aforementioned variants. The firefighting vehicle is preferably an airfield firefighting vehicle, which is used in the vicinity of airports to fight fires, such as burning aircraft or helicopters. During firefighting operations, it is advantageous to be able to implement the pump-and-roll function, so that the airfield firefighting vehicle can slowly drive around the object to be extinguished.

[0021] The invention is not limited to the specified combination of features of the main claim or the dependent claims. Furthermore, possibilities arise for combining individual features, even if they emerge from the claims, the following description of a preferred embodiment of the invention, or directly from the drawing. The reference of the claims to the drawing by the use of reference symbols is not intended to limit the scope of protection of the claims.

[0022] The only figure shows a schematic view of a fire engine drive train 1 according to a preferred embodiment of the invention, wherein this fire engine drive train 1 is part of a fire engine, which is in particular an airfield fire engine.

[0023] As can be seen in the single figure, the fire engine drive train 1 comprises a first drive engine 2, which is an internal combustion engine. On the output side of the drive engine 2, a motor vehicle transmission 3 is provided, in which several different transmission ratios can be switched in order to be able to transmit the drive movement of the drive engine 2 in different ways. Between the drive engine 2 and the motor vehicle transmission 3, there is also an intermediate transmission 4 in the form of a spur gear stage (not shown in detail), via which the drive movement of the drive engine 2 is permanently transmitted with a fixed transmission ratio to a drive shaft 5 of a fire pump 6 of the fire engine. Preferably, a separating clutch is also provided between the drive shaft 5 and the fire pump 6 in order to be able to initiate a drive movement in the fire pump 6 only during its fire-fighting operation.When this separating clutch is closed, the fire pump 6 is then operated via the drive motor 2. Further preferably, a starting element is provided between the first drive motor 2 and the motor vehicle transmission 3, which can be a friction clutch or a hydrodynamic torque converter.

[0024] The motor vehicle transmission 3 is connected on the output side via an intermediate shaft 7 to a transmission input 8 of a transfer case 9, via which a drive power is distributed to two transmission outputs 10 and 11, to each of which a cardan shaft 12 or 13 is connected. The cardan shafts 12 and 13 then lead to an axle drive 14 or 15, respectively, of a drive axle 16 or 17, respectively, with further distribution to drive wheels 18 and 19, or 20 and 21, of the respective drive axle 16 or 17 being carried out via the individual axle drive 14 or 15.

[0025] In addition to the first drive motor 2, the fire engine drive train 1 also includes a further, second drive motor 22, which is in the form of an electric motor 23. This electric motor 23 is connected in parallel to the first drive motor 2 by being coupled to a second transmission input 25 of the transfer case 9 via an intermediate transmission 24. The transmission 24 is preferably designed with two stages and further preferably includes a separating clutch, via which the electric motor 23 can be decoupled from the transmission input 25.

[0026] During normal travel of the fire engine, a drive movement to represent high acceleration can be realized both via the first drive motor 2 and via the electric motor 23, wherein the transfer case 9 in this case adds together the drive power of the first drive motor 2 and the electric motor 23 and distributes it between the two drive axles 16 and 17. In addition, when the fire engine is traveling, a targeted boost can also be realized via the electric motor 23 when driven by the first drive motor 2. Furthermore, during braking operations, it is conceivable to recuperate electrical energy via the electric motor 23 by operating it as a generator in this case. The motor vehicle transmission 3 is preferably switched to neutral so that the first drive motor 2 is not dragged along.

[0027] To represent an extinguishing operation in which a high power is to be transferred to the extinguishing pump 6 while the fire engine is traveling slowly, the vehicle transmission is switched to neutral and the drive power of the first drive motor is transferred completely to the extinguishing pump 6 via the intermediate intermediate gear ratio 4. The fire engine is driven solely by the electric motor 23, which distributes its drive power to the two drive axles 16 and 17 via the intermediate gear 24 and the transfer case 9. This allows the fire engine to travel slowly around the object to be extinguished while simultaneously transferring high power to the extinguishing pump in extinguishing operation, also known as pump & roll operation.

[0028] By means of the design of a fire engine drive train according to the invention, a suitable drive of a fire pump and at least one drive axle can be realized with a simple structure within the scope of a fire-fighting operation. Reference symbol 1 fire engine drive train 2 drive machine 3 Motor vehicle transmissions 4 Intermediate translation 5 Drive shaft 6 fire pump 7 Wave 8 Gearbox input 9 transfer cases 10 Gearbox output 11 Gearbox output 12 Cardan shaft 13 Cardan shaft 14 axle drives 15 axle drives 16 drive axle 17 Drive axle 18 Drive wheel 19 Drive wheel 20 drive wheel 21 Drive wheel 22 drive machine 23 Electric machine 24 gearboxes 25 Gearbox input

Claims

[1] Firefighting vehicle drive train (1), in particular for an airfield firefighting vehicle, comprising a first drive motor (2) which can be drivenly connected to at least one drive axle (16, 17), wherein the first drive motor (2) is also driveably connectable or connected to at least one fire pump (6), wherein a second drive motor (22) in the form of an electric machine (23) is provided which is driveably connected or connectable to the at least one drive axle (16, 17) in parallel to the first drive motor (2), wherein the first drive motor (2) can be drivenly connected to the at least one drive axle (16, 17) via an intermediate motor vehicle transmission (3), wherein different transmission ratios can be switched between a transmission input and a transmission output in the motor vehicle transmission (3),and wherein the first drive machine (2) is or can be connected to the at least one fire pump (6) via an intermediate transmission (4), characterized by that the intermediate transmission (4) is integrated between the first drive machine (2) and the motor vehicle transmission (3), and that a drive-side component of the intermediate transmission (4) is connected in a rotationally fixed manner to an output of the first drive machine (2) or the transmission input of the motor vehicle transmission (3). [2] Fire engine drive train (1) according to claim 1, characterized by that the first drive machine (2) is designed as an internal combustion engine. [3] Fire engine drive train (1) according to one of the preceding claims, characterized by that several drive axles (16, 17) are provided, each of which is coupled to a transfer case (9). [4] Fire engine drive train (1) according to claim 3, characterized bythat the transfer case (9) has a first transmission input (8), which serves for a connection to the first drive machine (2), and a second transmission input (25), which is provided for a coupling to the electric machine (23). [5] Fire engine drive train (1) according to one of the preceding claims, characterized by that the electric machine (23) can be connected to the at least one drive axle (16, 17) via an intermediate transmission (24), wherein different transmission ratios can be switched in the transmission (24). [6] Firefighting vehicle, in particular an airfield firefighting vehicle, comprising a firefighting vehicle drive train (1) according to one or more of claims 1 to 5.

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