WORKING MACHINE AND METHOD FOR DETERMINING THE LOAD SPECIFICATION OF A FUEL CELL

Description

[0001] The present invention relates to a work machine, preferably a mobile work machine and in particular wheel loaders and telescopic loaders, excavators with wheel and crawler chassis, articulated dump trucks, as well as bulldozers and crawler loaders, with a fuel cell drive, comprising a fuel cell and determining means for determining the load specification of the fuel cell, wherein the work machine has a plurality of electrical consumers which are connected to the fuel cell directly or indirectly for the purpose of obtaining electrical energy.

[0002] It is known from the prior art to equip cars with fuel cell propulsion. Hydrogen is fed into a fuel cell, which reacts with oxygen in a chemical process. The energy stored in the hydrogen is released as electrical energy, which is used to drive an electric motor and / or charge a battery. In cars, which typically have only one main drive, the fuel cell's load is usually based on the driver's desired output, i.e., the accelerator pedal position.

[0003] The load specification is the power value at which the fuel cell is to be operated.

[0004] To extend the service life of the fuel cell, it may be advisable to limit the power dynamics and shutdown processes on the fuel cell, thereby shifting the load power to the battery. However, if the system is to achieve maximum efficiency, the power loss on the fuel cell and battery must be minimized and the operating strategy adjusted.

[0005] For work machines, such as wheel loaders and other earthmoving and material handling machines, this procedure plays a minor role if they have several main drives, such as electric motors on the individual axles or individual wheels, since the main drives have independent power requirements.

[0006] US 2021 / 296666 A1 discloses a work machine with a control device for controlling a power supply device. Furthermore, a load detection unit is provided, by means of which a load quantity of the work machine is detected or output. Based on the load quantity, the power rate of a fuel cell is determined by means of a determination unit.

[0007] The present invention is based on the object of developing a working machine of the type mentioned at the outset in such a way that the load specification of the fuel cell can be determined as precisely as possible.

[0008] This object is achieved by a work machine having the features of claim 1.

[0009] According to this, the means for determining the fuel cell's load specification are designed such that the power requirements of at least two of the electrical consumers are taken into account when determining the fuel cell's load specification. The electrical consumers are preferably the main drives of the work machine, i.e., those drives that serve to propel the work machine, move the work equipment, and steer the machine.

[0010] Preferably, the plurality of main drives each have an independent power requirement, so that a corresponding regulation or control of the fuel cell load specification is advantageous.

[0011] In one embodiment of the invention, first detection means are provided which are designed to detect one or more machine data which influence the fuel cell and / or a battery which is electrically connected to the fuel cell, wherein the determination means are designed to incorporate the machine data into the load specification of the fuel cell.

[0012] The machine data can be data that influences the service life, aging, efficiency or the efficiency of the fuel cell and / or the battery.

[0013] At this point, it should be noted that the term "fuel cell" in the context of the present invention can refer to both the fuel cell as such and a combination of the fuel cell with a battery that is powered by the fuel cell.

[0014] In the context of the present invention, the term "fuel cell" may alternatively or in addition to the battery and / or the fuel cell also include one or more, preferably all, components and assemblies required for the operation of a fuel cell stack and system, such as process air production and humidification and other system components as well as a voltage boost converter (DC-DC converter) which increases the power-dependent, variable output voltage of the stack to the level of the battery voltage.

[0015] In work machines according to the present invention, the hydraulic drives can also take on the function of main drives.

[0016] The process for determining the load specification can be operated on a vehicle control unit and thus outsourced and carried out independently of independent component control units of the fuel cell system and the voltage boost converter (DC-DC converter), which receive the load specification signal from the vehicle control unit.

[0017] The work machine is designed in one embodiment with such a vehicle control unit.

[0018] According to the invention, filter means are provided that are designed to temporally filter the power requirements of the at least two electrical consumers. This means that the power requirements of the consumers are determined and a check is carried out to determine whether they can be operated simultaneously or at different times, which influences the load requirements of the fuel cell.

[0019] Furthermore, second detection means are provided which are designed to detect past data of the working machine, wherein the determination means are designed to incorporate the past data into the load specification of the fuel cell.

[0020] These past data, i.e. data from the past in time, include the past power requirements of the working machine or of one or more consumers of the working machine.

[0021] It is conceivable that the second detection means are designed to create forecast data from the past data, i.e. a forecast for the power requirement, and the determination means are designed to incorporate the forecast data into the determination of the load specification of the fuel cell.

[0022] Furthermore, it can be provided that the determination means are designed to process the data supplied to them in a cascade manner.

[0023] Preferably, at least two of the consumers are main drives of the working machine.

[0024] Alternatively or additionally, the load(s) may be individual loads that are not the main drives of the machine. Examples of individual loads include smaller hydraulic drives, heating and / or cooling devices, fans, etc.

[0025] The work machine can have a vehicle control unit that has one or more of the aforementioned components (determination means, filter means, detection means) and that is thus outsourced and independent of independent component control units of the fuel cell system and the voltage boost converter (DC-DC converter).

[0026] The present invention further relates to a method for determining the load specification of a fuel cell of a work machine, wherein the work machine has a plurality of electrical consumers that are directly or indirectly connected to the fuel cell for the purpose of drawing electrical energy. The power requirements of at least two of the electrical consumers are taken into account when determining the load specification of the fuel cell. These are preferably two or more than two main drives of the preferably mobile work machine.

[0027] It is preferably provided that data from one or more of claims 2 to 10 are included in the determination of the load specification. The subject matter of the work machine is thus also an optional subject matter of the method according to the invention.

[0028] In one embodiment of the invention, it is provided that the load specification is determined by cascade-like processing of data influencing the load specification.

[0029] The method according to the invention for determining the load specification can be operated on a vehicle control unit and thus outsourced and independent of independent component control units of the fuel cell system and / or voltage boost converters (DC-DC converters).

[0030] In a preferred embodiment, the invention relates to the load specification for fuel cell drives in working machines with several main drives, wherein in addition to the power requirement of preferably all individual main drives, various machine parameters are used to determine the load specification and processed in a cascade control.

[0031] The essential features of a preferred embodiment are: Determination of the power requirement for vehicles with at least two independent main drives Determination of the power requirement of all other individual consumers Determination of essential machine parameters Consideration of previous measured values for influencing the control system Processing of the relevant values in a cascade control system

[0032] When operating the work machine, it may be useful to pursue different operating strategies.

[0033] It should be noted here that the terms "a" and "an" do not necessarily refer to exactly one of the elements, although this is a possible interpretation, but can also refer to a plurality of the elements. Likewise, the use of the plural also includes the presence of the element in question in the singular, and conversely, the singular also encompasses several of the elements in question.

[0034] Furthermore, it should be noted that each feature of the present invention may be combined with any other feature or several other features of the present invention. Thus, any combination of features is also subject to the present disclosure.

[0035] Further details and advantages of the invention are explained in more detail with reference to an embodiment shown in the drawing.

[0036] The single figure shows a schematic view of the control system for determining the load specification of a fuel cell of a working machine, not shown in the figure.

[0037] The work machine can be, for example, a wheel loader or telehandler, excavator with wheel and crawler chassis, articulated dump trucks, as well as bulldozers and crawler loaders or other earthmoving or construction machinery.

[0038] The work machine is preferably a mobile work machine.

[0039] The load specification L of the fuel cell is determined in the determination unit B.

[0040] In the first part of the control system, the power demand of all load consumers (component 1: K1, component 2: K2, component n: K) is determined, and a total power requirement 10 for the fuel cell is calculated based on the operating strategy. The dynamics of the load demand are influenced using temporal filtering 20.

[0041] As further shown in the figure, key machine parameters such as the battery's charge level and its changes are recorded in parallel. Reference numeral 30 denotes the battery's state variables.

[0042] In order to operate the battery within the permissible limits, a controller 40 determines an additional power requirement for compensation, which is applied when calculating the power or load requirement L of the fuel cell, as shown in the figure.

[0043] The value compensated in this way is denoted by W in the figure. The value W is fed to the determining means B.

[0044] The second part of the control system influences the operating strategy. For this purpose, various machine and component data 50 are read or measured using the first acquisition device, which provides information about the aging processes of the fuel cell and battery.

[0045] The reference number 60 indicates the efficiency of the overall fuel cell and battery system.

[0046] The service life or aging of the entire fuel cell and battery system is indicated by 70. As can be seen from the figure, these values are combined to form a first part W1 of the correction 100 of the value W supplied to the determination means B, which is calculated based on blocks 20, 40.

[0047] Depending on the selected operating strategy, a target power value is then determined, which is then adjusted to the fuel cell's total load requirement L. The correction value is designated W1 in the figure.

[0048] The third part considers the vehicle application and its operating conditions. Based on historical machine data, such as the previous power requirement of the working machine 80, which is recorded over a defined period of time using the second recording means, it is possible to identify recurring work patterns. By appropriately predicting work patterns (see reference numeral 90: predictive power requirement of the working machine), the operating strategy can be influenced, and the fuel cell power can be adapted to the required power requirement at an early stage.

[0049] Once operating patterns are recognized and predicted, the fuel cell's load requirement can be adjusted in the third part of the control system through a further correction. The correction value is designated W2.

[0050] Both correction values W1 and W2 are combined in the correction unit 100 and based on this a final correction value W3 is determined, which is fed to the determination means B.

[0051] In the determination means B, the value W is thus corrected using the correction value W3. Based on these two values (W and W3), the determination means B then ultimately determines the load requirement L at which the fuel cell is actually operated.

[0052] The aforementioned chronological list of the individual control blocks is not mandatory. Any other sequence of the aforementioned steps is also encompassed by the invention.

[0053] Advantages of a preferred embodiment are set out below: The invention preferably relates to a method for determining the power requirement for operating a fuel cell drive in a vehicle, wherein the vehicle has several electric main drives, the individual power requirements of which are determined and used in a vehicle control system to determine a total vehicle power requirement.

[0054] Preferably, it is a vehicle with several electric main drives, whereby the vehicle is a mobile work machine.

[0055] According to the invention, the total vehicle power requirement is determined from the data of the individual drives with appropriate temporal filtering.

[0056] Battery state variables such as state of charge and its change are used to correct the power requirement.

[0057] The efficiency chain of the components of the fuel cell electric drive, preferably the battery, the fuel cell and the DC / DC converter, is taken into account to correct the power requirement.

[0058] Furthermore, the aging of the components of the fuel cell electric drive, preferably the battery and the fuel cell, is taken into account to correct the power requirement.

[0059] The fuel cell power requirement is optimized and refined by utilizing a load prediction method that evaluates the vehicle's operating history with the aim of reducing energy consumption and aging.

Claims

1. A work machine having a fuel cell drive comprising a fuel cell and determination means for determining the load demand of the fuel cell, wherein the work machine has a plurality of electrical consumers that are directly or indirectly connected to the fuel cell for the purpose of obtaining electrical energy, wherein the determination means are configured such that the power requirements of at least two of the electrical consumers enter into the determination of the load demand of the fuel cell, characterized in that that filter means are present that are configured to filter the power requirements of the at least two electrical consumers over time; and in that in that second detection means are provided that are configured to detect historical data of the work machine with the determination means being configured to allow the historical data to enter into the load demand of the fuel cell, and with historical data comprising the past power requirement of the work machine or the past power requirement of one or more consumers of the work machine.

2. A work machine in accordance with claim 1, characterized in that first detection means are present that are configured to detect one or more pieces of machine data that have an influence on the fuel cell and / or on a battery electrically connected to the fuel cell; and in that the determination means are configured to allow the machine data to enter into the load demand of the fuel cell.

3. A work machine in accordance with claim 2, characterized in that the machine data are those data that have an influence on the service life, aging, degree of efficiency, and / or on the efficiency of the fuel cell and / or of the battery.

4. A work machine in accordance with one of the preceding claims, characterized in that the second detection means are configured to prepare forecast data from the historical data; and in that the determination means are configured to allow the forecast data to enter into the determination of the load demand of the fuel cell.

5. A work machine in accordance with one of the preceding claims, characterized in that the determination means are configured to process these supplied data in a cascade-like manner.

6. A work machine in accordance with one of the preceding claims, characterized in that that at least two of the consumers are main drives of the work machine; and / or in that the consumer or consumers are individual consumers that are not main drives of the work machine.

7. A work machine in accordance with one of the preceding claims, characterized in that a vehicle control unit is present that has one or more of the aforesaid components and that is outsourced and is independent of standalone component control units of the fuel cell and / or of the battery and / or of the fuel cell system and / or of the voltage boost converter (DC-DC converter).

8. A method of determining the load demand of a fuel cell of a work machine, wherein the work machine has a plurality of electrical consumers that are directly or indirectly connected to the fuel cell for the purpose of obtaining electrical energy, wherein the power requirements of at least two of the electrical consumers enter into the determination of the load demand of the fuel cell, characterized in that r the power requirements of the at least two electrical consumers are filtered over time; and in that historical data of the work machine are detected and the historical data enter into the load demand of the fuel cell, with the historical data comprising the past power requirement of the work machine or the past power requirement of one or more consumers of the work machine.

9. A method in accordance with claim 8, characterized in that data of one or more of claims 2 to 6 enter into the determination of the load demand.

10. A method in accordance with claim 8 or claim 9, characterized in that the determination of the load demand takes place by a cascade-like processing of data having an influence on the load demand.