Industrial truck with an electric drive and a temperature sensor

Abstract

The invention relates to a forklift truck (1) comprising an electric drive (15) configured to drive the forklift truck (1), wherein the electric drive (15) has at least a first drive component (35) and at least a second drive component (33), wherein the at least one second drive component (33) is thermally coupled to the first drive component (35), a temperature sensor (31) configured to detect a temperature value of the first drive component (35) of the electric drive (15), and a control unit (16) configured to determine a temperature value of the second drive component (33) based on the detected temperature value of the first drive component (35) and on the basis of a temperature model (37).

Description

[0001] The invention relates to a forklift truck with an electric drive, a temperature sensor configured to detect a temperature value of a first drive component of the electric drive, and a control unit configured to determine a temperature value of a second drive component of the electric drive based on the detected temperature value of the first drive component and on the basis of a temperature model.

[0002] Furthermore, the invention relates to a method for determining a temperature value of a second drive component of an electric drive of a forklift truck.

[0003] Industrial trucks include, for example, counterbalance forklifts, reach trucks, and warehouse equipment. These types of industrial trucks are widely used on company premises and in storage areas, such as warehouses, to transport goods. They feature height-adjustable load-handling devices on a lifting mast to pick up goods, move them within storage areas, and then set them down again.

[0004] A forklift truck typically has an electric drive with an electric drive motor, which can set one or more drive wheels of the forklift truck in motion to move the forklift truck.

[0005] During operation, the electric drive motor generates heat depending on the load, causing its components to warm up. Depending on the operating time, the weight of goods being transported on the forklift, and / or whether the forklift is traveling on an incline, the components of the electric drive can heat up to such an extent that, depending on the material of the components, damage may occur. Particularly heat-sensitive components of an electric forklift drive include, for example, a shaft seal made of a plastic with limited heat resistance, which is designed to seal a gearbox or brake compartment from the electric drive motor, and the winding head of the electric drive motor, which can heat up significantly under heavy loads.

[0006] To prevent damage to heat-sensitive components of an electric drive, especially a shaft seal or a winding head, the power of the electric drive motor is often limited in conventional industrial trucks when temperatures in the electric drive are too high, which can lead to a reduced usability of the industrial truck.

[0007] However, with conventional industrial trucks, a problem arises: due to space constraints, suitable temperature sensors for measuring the temperature of the electric drive can only be installed at specific locations within the drive unit. Therefore, precise temperature measurements can only be taken at these specific locations. In particular, direct temperature measurement is usually impossible at certain heat-sensitive components of the electric drive, such as the shaft seal and winding head of the electric drive motor, due to space limitations.

[0008] Since precise temperature measurements are not carried out for all components in conventional industrial trucks, especially not for all heat-sensitive components of the electric drive, the corresponding power limitation of the electric drive in conventional industrial trucks is very conservative, which can lead to a power limitation of the electric drive even though the actual temperature of a corresponding heat-sensitive component of the electric drive is still significantly below a maximum possible operating temperature.

[0009] Thus, the lack of direct temperature measurement on heat-sensitive components of the electric drive in conventional industrial trucks, such as the shaft seal and winding head of the electric drive motor, leads to the disadvantage that there is an unnecessary reduction in the power output of the electric drive of a correspondingly conventional industrial truck.

[0010] This has the disadvantage that, in certain operating conditions of a conventional industrial truck, the maximum required power of the electric drive cannot be accessed. Furthermore, a conventional industrial truck cannot react situationally to changes in the load on the electric drive. Therefore, the full potential of the electric drive often cannot be utilized in conventional industrial trucks.

[0011] In the publication DE 10 2004 0321 167 A1, a drive device of an industrial truck with a brake rotor designed as a speed sensor and a pulse generator rotor is disclosed.

[0012] In the publication DE 10 2013 110 569 A1, a sensor arrangement for detecting the rotational speed and / or direction of rotation of a shaft rotatable about a rotary axis of an electric drive of an industrial truck is disclosed.

[0013] In the publication DE 10 2008 061 449 A1, a drive axle of an industrial truck with an electric drive motor is disclosed.

[0014] The present invention is based on the objective of providing a forklift truck with an electric drive which overcomes the aforementioned disadvantages.

[0015] This task is solved according to a first aspect by a forklift truck comprising an electric drive which is configured to drive the forklift truck, wherein the electric drive has at least a first drive component and at least a second drive component, wherein the at least one second drive component is thermally coupled to the first drive component, a temperature sensor which is configured to detect a temperature value of the first drive component of the electric drive, and a controller which is configured to determine a temperature value of the second drive component based on the detected temperature value of the first drive component and on the basis of a temperature model.

[0016] This achieves the technical advantage that if the temperature value of the first drive component, which is thermally coupled to the second drive component, is available to the controller, the controller can effectively determine a temperature value of the second drive component based on the temperature model stored in the controller.

[0017] This allows for effective indirect temperature determination of the second drive component without the need for direct temperature measurement. This is because, due to space constraints, installing a temperature sensor on the second drive component is often not feasible. This problem is effectively circumvented by the control system using appropriate temperature modeling of the second drive component's temperature value.

[0018] The first drive component can comprise a single first drive component or a plurality of first drive components.

[0019] In particular, the first drive component comprises a drive housing, for example an axle housing, of the electric drive of the industrial truck, and the temperature sensor is arranged in particular within the drive housing of the electric drive in order to detect the temperature value of the drive housing, or the temperature value within the drive housing.

[0020] The second drive component can comprise a single second drive component or a plurality of second drive components.

[0021] In particular, the second drive component includes a shaft seal ring designed to seal a gearbox compartment or a brake compartment of the electric drive against an electric drive motor of the electric drive, and / or the second drive component includes a winding head of the electric drive motor of the electric drive.

[0022] For further details on the first drive component, in particular the drive housing, and on the second drive component, in particular the shaft seal and / or winding head, reference is made to the prior art documents cited above.

[0023] By indirectly determining the temperature of the second drive component, the control system of the industrial truck has a significantly more precise data basis available in order to increase the performance of the electric drive under heavy loads up to the thermal load limit of the second drive component, so that the performance of the electric drive can be fully utilized.

[0024] At the same time, the indirect determination of the temperature value of the second drive component ensures that a critical maximum temperature of the second drive component is not exceeded, thus preventing heat-related wear or even heat-related failure of the second drive component.

[0025] A corresponding temperature model stored in the control system takes into account the temperature value of the first drive component, as measured directly by the temperature sensor, when determining the temperature value of the second drive component. Due to the thermal coupling between the first and second drive components, the temperature model can precisely estimate the temperature of the second drive component based on the measured temperature of the first.

[0026] The temperature model may have been optimized in particular on the basis of direct reference measurements of the temperature of the first drive component and the temperature of the second drive component on an equivalent electric drive at the manufacturer of the industrial truck, taking into account in particular the thermal conductivity of the first drive component and / or the second drive component.

[0027] Furthermore, the temperature model can also include a self-learning algorithm, which has been trained by the manufacturer of the industrial truck by comparing certain temperature values ​​of the second drive component with temperature values ​​of a second drive component obtained through direct measurement with a temperature sensor, in order to enable an adaptation or training of the temperature model by the manufacturer.

[0028] According to an advantageous embodiment, the control system is designed to control the electric drive depending on the specific temperature value of the second drive component.

[0029] This achieves the technical advantage of enabling precise, and especially situationally variable, power adjustment of the electric drive, thereby fully exploiting the performance of the electric drive.

[0030] According to an advantageous embodiment, the control system is configured to compare the determined temperature of the second drive component with a reference temperature of the second drive component in order to obtain a temperature comparison, and wherein the control system is configured to regulate the electric drive depending on the determined temperature comparison.

[0031] This achieves the technical advantage that by comparing the determined temperature of the second drive component with the reference temperature of the second drive component, it can be effectively determined whether a further increase in the performance of the electric drive is possible, or whether a reduction in the performance of the electric drive is necessary.

[0032] In particular, the reference temperature of the second drive component includes a maximum temperature at which the second drive component can be operated safely without sustaining damage. The reference temperature of the second drive component specifically includes a predetermined reference temperature, which was determined in advance, in particular, through reference measurements at the manufacturer of the industrial truck.

[0033] According to an advantageous embodiment, the control system is configured to increase the power of the electric drive, in particular the electrical power of an electric drive motor, when the specific temperature of the second drive component is lower than the reference temperature, and / or the control system is configured to reduce the power of the electric drive, in particular the electrical power of an electric drive motor, when the specific temperature of the second drive component is higher than the reference temperature.

[0034] This achieves the technical advantage of enabling effective, dynamic adjustment of the electric drive, particularly the electric drive motor, as required by the operating situation of the industrial truck. For example, if the reference temperature has not yet been reached, the electric drive motor can operate at its performance limit, and if, for example, the reference temperature has been reached, the power of the electric drive motor must be reduced.

[0035] In particular, the control system is configured to increase the electrical power of an electric drive motor to a maximum electrical power value when the specific temperature of the second drive component is lower than the reference temperature, and / or the control system is specifically configured to reduce the electrical power of an electric drive motor to a minimum electrical power value when the specific temperature of the second drive component is higher than the reference temperature.

[0036] This ensures that the maximum power of the electric drive motor can be fully utilized, or that in the event of an imminent overheating of the second drive component, electrical power can be immediately and significantly reduced by the electric drive motor.

[0037] According to an advantageous embodiment, the controller is configured to provide the detected temperature value of the first drive component as an input parameter to the temperature model, and the temperature model is configured to output the temperature value of the second drive component as an output parameter.

[0038] This achieves the technical advantage of ensuring effective operation of the temperature model.

[0039] According to an advantageous embodiment, the control system is configured to provide the temperature model with at least one of the following input parameters in addition to the detected temperature value of the first drive component: - a heat capacity of the electric drive, in particular a heat capacity of the first and / or second drive component, - an input power supplied to the second drive component, wherein the control system is specifically designed to determine the input power as a function of the motor speed and a coefficient of friction of the second drive component, - a motor speed of the electric drive, - a stator current and / or stator resistance applied to the electric drive, in particular to an electric drive motor of the electric drive, - a temperature of a drive axle of the electric drive as measured by another temperature sensor, and / or - the operating time of the industrial truck.

[0040] This achieves the technical advantage that by providing the additional input parameters, the temperature model can be improved, and the determination of the temperature of the second drive component can be improved.

[0041] According to an advantageous embodiment, the temperature model is configured to multiply the detected temperature value of the first drive component by a temperature-dependent factor to obtain the temperature value of the second drive component and / or the temperature model is configured to add a temperature deviation value to the detected temperature value of the first drive component to obtain the temperature value of the second drive component.

[0042] This achieves the technical advantage that by multiplying the measured temperature of the first drive component by the temperature-dependent factor, the temperature of the second drive component can be effectively determined. Depending on whether the temperature of the second drive component is higher or lower than the measured temperature of the first drive component, the temperature-dependent factor will have a value greater than 1 or a value less than 1.

[0043] Alternatively or additionally, the temperature model can add a temperature deviation value to the measured temperature of the first drive component to obtain the temperature value of the second drive component. Depending on whether the temperature of the second drive component is higher or lower than the measured temperature of the first drive component, the temperature deviation value is positive or negative.

[0044] According to an advantageous embodiment, the control system is designed to dynamically determine the temperature value of the second drive component during operation of the industrial truck, based on the detected temperature value of the first drive component and on the basis of the temperature model.

[0045] This achieves the technical advantage that the control system can react situationally, particularly in real time, to changes in the temperature of the second drive component. Specifically, the control system is designed to periodically determine the temperature of the second drive component during operation of the industrial truck, based on the measured temperature of the first drive component and the temperature model. This allows for temperature monitoring and, if necessary, adjustment of the electric drive's power output at regular intervals, which can be as short as a few seconds.

[0046] According to an advantageous embodiment, the first drive component comprises an axle housing of the electric drive, and the at least one second drive component comprises at least a winding head of an electric drive motor of the electric drive and / or a shaft seal which seals a brake chamber of a brake device and / or a gearbox chamber of a gearbox against an electric drive motor of the electric drive, wherein the temperature sensor is arranged in the axle housing and is configured to detect a temperature value of the axle housing and / or a temperature value within the axle housing.

[0047] This achieves the technical advantage that the temperature sensor effectively measures the temperature of the axle housing, or the temperature within the axle housing. Based on this measured temperature and the temperature model, the control system can then effectively determine the temperature of the winding head and / or the shaft seal. This is particularly advantageous because the material of the winding head and / or the shaft seal is heat-sensitive, and direct measurement of the temperature of the winding head and / or the shaft seal is not possible due to space constraints.

[0048] According to an advantageous embodiment, the electric drive comprises two electric traction motors which are arranged coaxially to each other, wherein each of the two electric traction motors has at least one, in particular two, winding heads, and / or each electric traction motor is assigned a gearbox and / or a brake compartment, wherein a shaft seal is arranged between the respective electric traction motor and the gearbox or brake compartment in order to seal the gearbox or brake compartment of the brake device against the respective electric traction motor.

[0049] This achieves the technical advantage of effective temperature determination for at least one winding head of the two electric drive motors and / or for the respective shaft seal.

[0050] According to an advantageous embodiment, the at least one electric traction motor has a stator and a rotor arranged in the axle housing, wherein the rotor is non-rotatably connected to a rotor shaft of the electric drive, wherein the stator has the at least one winding head, and / or wherein the shaft seal is arranged between the rotor shaft of the electric traction motor and the gearbox or brake compartment in order to seal the gearbox or brake compartment against the respective electric traction motor.

[0051] This achieves the technical advantage that effective operation of the electric drive motor is achieved by appropriately determining the temperature of the winding head and / or the shaft seal.

[0052] According to an advantageous embodiment, the industrial truck has a memory, and the control system is designed to store the determined temperature value of the second drive component in the memory.

[0053] This achieves the technical advantage that the control system can access the stored temperature value of the second drive component at any time. Specifically, the control system is designed to store the defined temperature value of the second drive component, along with information about the operating time of the industrial truck, in its memory so that the control system can access it.

[0054] According to an advantageous embodiment, the control system is configured to load a specific temperature value of the second drive component from the memory, which is stored in the memory, in particular during a previous activation of the industrial truck.

[0055] This achieves the technical advantage that the control system can use the temperature value of the second drive component loaded from the memory, for example when restarting the industrial truck.

[0056] If the temperature value of the second drive component is stored in the memory along with information about the operating time of the industrial truck, the controller is specifically designed to determine the second temperature value of the second drive component based on the recorded first temperature value of the first drive component and the information about the stored operating time. For example, the controller can compare the stored operating time with the current operating time of the industrial truck and, for example, determine the temperature of the second drive component after the industrial truck restarts.

[0057] This problem is solved according to a second aspect by a method for determining a temperature value of a second drive component of an electric drive of a forklift truck, wherein the forklift truck comprises an electric drive configured to drive the forklift truck, wherein the electric drive has at least a first drive component and at least one second drive component, wherein the at least one second drive component is thermally coupled to the first drive component, and wherein the forklift truck has a temperature sensor and a controller, wherein the method comprises the following process steps: detecting a temperature value of the first drive component of the electric drive by the temperature sensor, and determining a temperature value of the second drive component based on the detected temperature value of the first drive component and on the basis of a temperature model by the controller.

[0058] This achieves the technical advantage that an effective determination of the temperature of the second drive component of the electric drive is possible.

[0059] According to an advantageous embodiment, the method comprises the further process step: controlling the electric drive depending on the determined temperature value of the second drive component by the control unit.

[0060] This achieves the technical advantage that effective adjustment of the power of the electric drive depending on the temperature of the second drive component results in an optimization of performance and a reduction of heat-induced damage.

[0061] The embodiments mentioned for the industrial truck according to the first aspect are also embodiments for the method according to the second aspect and vice versa.

[0062] Further advantages and details of the invention are explained in more detail by way of example with reference to the embodiments shown in the schematic figures. Here, it is shown that the Fig. Figure 1 shows a forklift truck with an electric drive comprising an axle according to an exemplary embodiment, the Fig. Figure 2 shows an electric drive comprising a drive axle of the in Fig. 1. Forklift truck shown, according to an exemplary embodiment, the Fig. Figure 3 shows a schematic representation of a temperature model and a temperature control of an electric drive of a forklift truck according to an embodiment of the present invention and the Fig. Figure 4 shows a schematic representation of a method for determining a temperature value of a second drive component of an electric drive of a forklift truck according to an embodiment of the present invention.

[0063] The Fig. Figure 1 shows a forklift truck 1 with an electric drive comprising a drive axle according to an exemplary embodiment.

[0064] The one in Fig. The industrial truck 1, in particular a forklift truck, shown in Figure 1, has a vehicle body 3 with a driver's cab 5 in which a driver of the industrial truck 1 can sit. The industrial truck 1 has a height-adjustable load-handling device 9, in particular a load fork, arranged on a lifting mast 7, by means of which the industrial truck 1 can pick up and set down goods in a warehouse.

[0065] The industrial truck 1 also has drive wheels 11, by means of which the industrial truck 1 can move on a surface 13, for example the floor of a warehouse. To drive the drive wheels 11, the industrial truck 1 has a Fig. 1 an electric drive 15 arranged on the drive axle, in particular the front axle and / or rear axle, which is only shown schematically.

[0066] A control unit 16 of the industrial truck 1 is located in the Fig. 1 is shown only schematically.

[0067] The Fig. Figure 2 shows a section of an electric drive 15 comprising a drive axle of the in Fig. 1. Forklift truck shown according to an exemplary embodiment.

[0068] In the Fig. Figure 2 shows only a section of the corresponding drive axle of the electric drive 15, showing only one of the two electric drive motors 17 of the electric drive 15. The Fig. The electric traction motor 17 shown in Figure 2 has a rotor shaft 21 non-rotatably connected to a rotor 19 and a stator 25 arranged in the axle housing 23 of the drive axle. The rotor shaft 21 extends along the axis of rotation of the electric traction motor 17. Fig. Figure 2 also shows two winding heads 26 of the electric drive motor 17.

[0069] The rotor shaft 21 is rotatably mounted in the axle housing 23 by means of a bearing 27 on each side. A shaft seal 29 is provided in the area of ​​each bearing 27, which has a Fig. 2 seals the gearbox compartment of a gearbox or a brake compartment of a brake device of the axle housing 23 against the respective electric drive motor 17.

[0070] From the Fig. Figure 2 shows that a temperature sensor 31 is arranged in the axle housing 23, which is designed to detect a temperature within the axle housing 23 of the electric drive 15. According to the temperature sensor 31, only a local temperature measurement can be achieved within the axle housing 23, and it is not possible to directly measure the temperature of all components of the electric drive 15, since, for example, a temperature sensor cannot be effectively positioned on the shaft seal 29 or the winding head 26 of the electric drive motor 17.

[0071] During operation of the electric drive 15, especially during peak loads, the electric drive 15, and in particular certain components of the electric drive 15, may become very hot, which can damage the material of the electric drive 15 or its components.

[0072] In conventional industrial trucks 1, to avoid temperature spikes, drive components must be throttled depending on measured component temperatures. Alternatively, for components of the electric drive 15 whose temperature cannot be directly measured during operation, it must be ensured that they withstand all required loads and that no wear or component failure occurs due to elevated temperatures. This can lead to the maximum possible power of the electric drive 15 not being available in certain operating conditions, and there is no way to react situationally to loads on the electric drive 15.

[0073] The present invention aims to indirectly determine the temperatures of particularly critical components of the drive train, so that a higher power output of the drive train can be temporarily requested until the maximum limit temperature of corresponding critical components is reached, thereby protecting the critical components by adjusting the power output of the electric drive 15.

[0074] In order to enable the indirect temperature measurement of critical components of the electric drive 15, the control unit 16 of the industrial truck 1 determines a temperature value of a critical second drive component 33, such as the shaft seal 29 and / or the winding head 26, of the electric drive 15 on the basis of the temperature value of a first drive component 35, such as the axle housing 23, of the electric drive 15, detected by means of the temperature sensor 31 and on the basis of a temperature model 37.

[0075] The temperature model 37 ensures that, based on the direct measurement of the temperature of the first drive component 35, such as the axle housing 23, an effective indirect estimation of the temperature of the critical second drive component 33, such as the shaft seal 29 and / or the winding head 26, can be achieved without the need for a direct temperature measurement on the second drive component 33.

[0076] In this process, the recorded temperature value of the first drive component 35, in particular the axle housing 23, is provided as an input parameter to the temperature model 37, and the temperature model 37 is configured to output the temperature value of the second drive component 33, in particular the shaft seal 29 and / or the winding head 26, as an output parameter.

[0077] In addition to the recorded temperature value of the first drive component 35, the controller 16 can provide the temperature model 37 with at least one of the following input parameters: a heat capacity of the electric drive 15, in particular a heat capacity of the first and / or second drive component 35, 33, an input power supplied to the second drive component 33, wherein the controller is in particular configured to determine the input power as a function of the motor speed of the traction motor 17 and a coefficient of friction of the second drive component 33, a stator current and stator resistance of the electric drive 15 applied to the electric traction motor 17, a motor speed of the electric drive 15, a temperature of a drive axle of the electric drive 15 recorded by a further temperature sensor, an operating time of the industrial truck 1, and mixtures thereof.

[0078] In this case, the temperature model 37 is particularly configured to multiply the sensor-detected temperature value of the first drive component 35, obtained as an input parameter, by a temperature-dependent factor in order to obtain the temperature value of the second drive component 33, and / or the temperature model 37 is particularly configured to add a temperature deviation value to the detected temperature value of the first drive component 35 in order to obtain the temperature value of the second drive component 33.

[0079] In particular, the control unit 16 is designed to dynamically determine the temperature value of the second drive component 33 based on the detected temperature value of the first drive component 35 and on the basis of the temperature model 37 during the operation of the industrial truck 1, so that the control unit 16 can react differently during different power consumptions of the electric drive 15.

[0080] The industrial truck 1 has, in particular, a memory, and the control unit 16 is configured to store the specified temperature value of the second drive component 33 in the memory. The control unit 16 is further configured, in particular, to load a temperature value of the second drive component 33 from the memory, especially one stored during a previous activation of the industrial truck 1, in order to be able to estimate, for example, after the industrial truck 1 has been stationary, to what extent the temperature of the second drive component 33 has decreased as a result of the standstill.

[0081] The control unit 16 is specifically designed to control the electric drive 15 depending on the determined temperature value of the second drive component 33.

[0082] For this purpose, the controller 16 can, for example, compare the detected temperature of the second drive component 33 with a reference temperature of the second drive component 33 to obtain a temperature comparison, and the controller 16 can regulate the electric drive depending on the determined temperature comparison.

[0083] The control unit 16 is specifically configured to increase the electrical power of the electric drive 15, in particular to a maximum power value, for example a maximum vehicle speed and / or a maximum vehicle acceleration, when the specific temperature of the second drive component 33 is lower than the reference temperature, and / or the control unit 16 is configured to reduce the electrical power of the electric drive 15, in particular to a minimum power value, for example a minimum vehicle speed and / or a minimum vehicle acceleration, when the specific temperature of the second drive component 33 is higher than the reference temperature.

[0084] This results in a significant performance increase of the electric drive 15 of the industrial truck 1, as the electric drive 15 can be operated close to its performance limit and yet effective component protection can be achieved for the individual component parts.

[0085] The Fig. Figure 3 shows a schematic representation of a temperature model 37 and a temperature control of an electric drive of a forklift truck 1 according to an embodiment of the present invention.

[0086] According to the exemplary embodiment of temperature model 37, Fig. 3 as input parameter the temperature T measured by means of the temperature sensor 31 Sensor of the first drive component 35, in particular the axle housing 23, as well as the stator current I applied to the electric traction motor 17 of the electric drive 15 Stator , as well as the engine speed n Motorsupplied to the electric drive motor 17 of the electric drive 15.

[0087] As in the exemplary embodiment of the Fig. As shown in Figure 3, the temperature model 37 outputs the temperature of the second drive component 33, in particular the temperature T, as an output parameter. WDR of the shaft seal 29 and / or the temperature T WK of the winding head 26, wherein the temperature model 37 determines the corresponding temperature values ​​T WDR and T WK to improve the temperature model 37 itself can be taken into account again.

[0088] In the Fig. Figure 3 also shows a schematic temperature control 39 of the electric drive 15, which is carried out, for example, by a control 16 of the industrial truck 1.

[0089] Here, the temperature control 39 compares the correspondingly determined temperature values ​​T. WDR and T WKwith a corresponding respective reference value T WDR , max and T WK , max If, as shown, the temperature values ​​T WDR greater than the corresponding reference value T WDR , max and / or the temperature value T WK greater than the corresponding reference value T WK , max If this is the case, then the control unit 16 of the industrial truck 1 is designed to reduce the electrical power of the electric drive motor 17 of the electric drive 15 in order to prevent damage to the shaft seal 29 or the shaft end 26. For this purpose, the maximum vehicle speed v can be reduced. max and / or the maximum vehicle acceleration acc max is reduced from a maximum value to a minimum value.

[0090] Even if this is in Fig. 3 is not shown, the control unit 16 of the industrial truck 1 can of course increase the electrical power of the electric drive motor 17 of the electric drive 15 if the temperature value T WDR smaller than the corresponding reference value T WDR, max and the temperature value T WK smaller than the corresponding reference value T WK, max is so that the electric drive motor 17 can be operated close to its optimum performance and a failure of the electric drive 15 is prevented.

[0091] This allows for increased component protection and increased availability of the industrial truck 1 for the user, while at the same time eliminating the need for additional sensors in the electric drive 15 in addition to the temperature sensor 31 already present, and no additional space is required.

[0092] The Fig.Figure 4 shows a schematic representation of a method for determining a temperature value of a second drive component of an electric drive of a forklift truck 1 according to an embodiment of the present invention.

[0093] The procedure includes, as a first step, the detection of a temperature value of the first drive component 35 of the electric drive 15 by the temperature sensor 31.

[0094] The procedure includes, as a second step, determining a temperature value of the second drive component 33 based on the recorded temperature value of the first drive component 35 and on the basis of a temperature model 37 by the controller 16. Reference symbol list 1 forklift truck 3 vehicle bodies 5 Driver's cab 7 lifting mast 9 Lifting devices 11 Drive wheel 13 Subsurface 15 Electric drive 16 Control 17 Electric drive motor 19 Rotor 21 Rotor shaft 23 axle housings 25 Stator 26 winding head 27 warehouses 29 Shaft seal 31 Temperature sensor 33 Second drive component 35 First drive component 37 Temperature model 39 Temperature control 50 methods for determining a temperature value of a second drive component 51 Recording a temperature value of the first drive component 53 Determining a temperature value of the second drive component QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2004 0321 167 A1

[0011] DE 10 2013 110 569 A1

[0012] DE 10 2008 061 449 A1

[0013]

Claims

[1] Industrial truck (1), comprising: an electric drive (15) which is designed to drive the industrial truck (1), wherein the electric drive (15) has at least a first drive component (35) and at least one second drive component (33), wherein the at least one second drive component (33) is thermally coupled to the first drive component (35), a temperature sensor (31) which is designed to detect a temperature value of the first drive component (35) of the electric drive (15), and a controller (16) which is designed to determine a temperature value of the second drive component (33) on the basis of the detected temperature value of the first drive component (35) and on the basis of a temperature model (37). [2] Industrial truck (1) according to claim 1, wherein the controller (16) is designed to control the electric drive (15) as a function of the determined temperature value of the second drive component (33). [3] Industrial truck (1) according to claim 2, characterized by in that the controller (16) is designed to compare the determined temperature of the second drive component (33) with a reference temperature of the second drive component (33) in order to obtain a temperature comparison, and wherein the controller (16) is designed to regulate the electric drive (15) as a function of the determined temperature comparison. [4] Industrial truck according to claim 3, characterized byin that the controller (16) is designed to increase the power of the electric drive (15), in particular the electrical power of an electric traction motor (17) of the electric drive (15), when the specific temperature of the second drive component (33) is lower than the reference temperature, and / or in that the controller (16) is designed to reduce the power of the electric drive (15), in particular the electrical power of an electric traction motor (17) of the electric drive (15), when the specific temperature of the second drive component (33) is higher than the reference temperature. [5] Industrial truck (1) according to one of the preceding claims, wherein the controller (16) is designed to provide the detected temperature value of the first drive component (35) as an input parameter to the temperature model (37), and wherein the temperature model (37) is designed to output the temperature value of the second drive component (33) as an output parameter. [6] Industrial truck (1) according to claim 5, characterized by that the controller (16) is designed to provide the temperature model (37) with at least one of the following input parameters in addition to the detected temperature value of the first drive component (35): - a heat capacity of the electric drive (15), in particular a heat capacity of the first and / or second drive component (35, 33), - an input power supplied to the second drive component (33), wherein the controller (16) is particularly designed to determine the input power as a function of the engine speed and a coefficient of friction of the second drive component (33), - a stator current intensity and / or stator resistance applied to the electric drive (15), in particular to an electric drive motor (17) of the electric drive (15), - a motor speed of the electric drive (15), - a temperature of a drive axle of the electric drive (15) detected by a further temperature sensor, and / or - an operating time of the industrial truck (1). [7] Industrial truck (1) according to one of the preceding claims, wherein the temperature model (37) is designed to multiply the detected temperature value of the first drive component (35) by a temperature-dependent factor in order to obtain the temperature value of the second drive component (33) and / or wherein the temperature model (37) is designed to add a temperature deviation value to the detected temperature value of the first drive component (35) in order to obtain the temperature value of the second drive component (33). [8] Industrial truck (1) according to one of the preceding claims, characterized by that the controller (16) is designed to determine the temperature value of the second drive component (33) on the basis of the detected temperature value of the first drive component (35) and on the basis of the temperature model (37) dynamically during operation of the industrial truck (1). [9] Industrial truck (1) according to one of the preceding claims, characterized byin that the first drive component (35) comprises an axle housing (23) of the electric drive (15), and in that the at least one second drive component (33) comprises at least one winding head (26) of an electric traction motor (17) of the electric drive (15) and / or a shaft sealing ring (29) which seals off a gear chamber of a gear device and / or a brake chamber of a brake device with respect to an electric traction motor (17) of the electric drive (15), wherein the temperature sensor (31) is arranged in the axle housing (23) and is designed to detect a temperature value of the axle housing (23) and / or a temperature value within the axle housing (23). [10] Industrial truck (1) according to claim 9, characterized byin that the electric drive (15) comprises two electric traction motors (17) which are arranged coaxially to one another, wherein each of the two electric traction motors (17) has at least one winding head, in particular two winding heads, and / or wherein each electric traction motor (17) is assigned a gear chamber and / or a brake chamber, wherein a shaft sealing ring (29) is arranged between the respective electric traction motor (17) and the gear chamber and / or the brake chamber in order to seal the gear chamber and / or the brake chamber of the braking device with respect to the respective electric traction motor (17). [11] Industrial truck (1) according to claim 9 or 10, characterized byin that the at least one electric traction motor (17) has a stator (25) arranged in the axle housing (23) and a rotor (19), wherein the rotor (19) is connected in a rotationally fixed manner to a rotor shaft (21) of the electric drive (15), wherein the stator (25) has the at least one winding head (26), and / or wherein the shaft sealing ring (29) is arranged between the rotor shaft (21) of the electric traction motor (17) and the gear chamber and / or the brake chamber in order to seal the gear chamber and / or the brake chamber of the braking device from the respective electric traction motor (17). [12] Industrial truck (1) according to one of the preceding claims, characterized by that the industrial truck (1) has a memory, and that the controller (16) is designed to store the determined temperature value of the second drive component (33) in the memory. [13] Industrial truck (1) according to claim 12, characterized bythat the controller (16) is designed to load a specific temperature value of the second drive component (33) stored in the memory, in particular stored during a previous activation of the industrial truck (1), from the memory. [14] Method (50) for determining a temperature value of a second drive component (33) of an electric drive (15) of an industrial truck (1), wherein the industrial truck (1) comprises an electric drive (15) which is designed to drive the industrial truck (1), wherein the electric drive (15) has at least a first drive component (35) and the at least one second drive component (33), wherein the at least one second drive component (33) is thermally coupled to the first drive component (35), and wherein the industrial truck (1) has a temperature sensor (31) and a controller (16), characterized by that the method (50) comprises the following method steps: Detecting (51) a temperature value of the first drive component (35) of the electric drive (15) by the temperature sensor (31), and Determining (53) a temperature value of the second drive component (33) on the basis of the detected temperature value of the first drive component (35) and on the basis of a temperature model (37) by the controller (16). [15] Method according to claim 14, characterized by that the method (50) comprises the further method step: controlling the electric drive (15) as a function of the determined temperature value of the second drive component (33) by the controller (16).

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