Process for controlling sliperiness by spraying a liquid organic deicer onto a traffic surface of an airfield

Abstract

The present invention relates to a method for combating ice by spraying a liquid organic de-icer onto a runway surface using a self-propelled spraying vehicle, the spraying vehicle comprising a control unit and a spraying device, comprising the following steps: - spraying the de-icer onto a first section of the runway surface and defining a first primary spraying time (1PT) assigned to the first section, and - spraying the de-icer onto a second section of the runway surface and defining a second primary spraying time (2PT) assigned to the second section, - providing a first de-icing time value (PT) assigned to the first section and a second de-icing time value (PT) assigned to the second section.- Re-entry into the first section at a first secondary entry time (1SEZ) and re-entry into the second section at a second secondary entry time (2SEZ) with the spray vehicle, - Detection of the re-entry into the respective section, and - Activation of a re-spraying of the de-icer onto the respective section of the movement area if, at the respective secondary entry time (1SEZ, 2SEZ), the respective primary spraying time (1PAZ, 2PAZ) has elapsed by more than the respective de-icing time value (EZ).

Description

[0001] The present invention relates to a method for combating ice by (re-)spraying a liquid organic de-icer onto a movement area of an airfield, as well as an associated control device, computer program product and gritting vehicle.

[0002] The movement areas of an airport, which include in particular runways, taxiways and the apron, must be free of snow and ice even in winter weather in order to ensure trouble-free and, above all, safe flight operations.

[0003] The tightly scheduled flight operations, the high safety-critical requirements and the sensitivity of the aircraft present airport-specific challenges that make de-icing on an airport's movement areas significantly more complex and demanding than would be the case on roads and paths outside the airport area.

[0004] With regard to the sensitive aircraft, for reasons of corrosion protection, conventional road salts are typically not used to de-icer the movement areas of an airport, but organic (movement area) de-icers in the form of (liquid) solutions or granules based on organic substances such as glycol, urea, acetate (salts of acetic acid) or formate (salts of formic acid).

[0005] Since the beginning of the 1990s, the use of de-icers based on acetates (salts of acetic acid) and formates (salts of formic acid) has been increasingly recommended, as these are more environmentally friendly and biodegradable than glycol- or urea-based de-icers.

[0006] In particular, liquid organic (moving area) de-icers can tend to evaporate after being applied over a large area to a greater extent than conventional road salts.

[0007] Timely re-spraying (application) of the liquid organic de-icer is therefore indicated more frequently and must also be more precisely timed. However, this is typically complicated by the fact that the time for re-application of the de-icer (unlike in conventional road environments) cannot be freely chosen, but must be aligned with the tightly scheduled flight operations. In other words, the spray vehicle applying the de-icer is typically dispatched to the runway with little advance notice (at short notice) when a "gap" in flight operations allows for the re-application of organic de-icer. It is not uncommon for there to be insufficient time for the spray vehicle to cover the entire runway in one go, resulting in de-icer being re-applied to only one section of the runway.

[0008] This section-by-section reapplication of de-icer often results in some sections of the movement area being reapplied more frequently than necessary, while others are reapplied too infrequently, thus increasing the risk of ice formation. As a result, this can lead to different friction coefficients in different sections of the movement area, which is detrimental to flight safety. Furthermore, more de-icer is applied in some sections than necessary, which is detrimental in terms of resource efficiency, environmental impact, and costs.

[0009] RU 2 770 218 C1 shows a method for combating ice using organic de-icer, while US 10 410 517 B2 shows a control device for controlling the distribution of liquid organic de-icer.

[0010] Based on the prior art, the present invention is based on the object of providing an improved method for combating ice by (re-)spraying a liquid organic de-icer onto a movement area of an airport, in particular with regard to resource efficiency and the safety of flight operations.

[0011] This object is achieved by the method according to the invention according to claim 1, the control device according to the invention according to claim 7, the computer program product according to the invention according to claim 8 and the spray vehicle according to the invention according to claim 9.

[0012] The method according to the invention for combating ice by (re-)spraying a liquid organic (movement area) de-icer (which is particularly designed as a solution based on glycol, urea, formate and / or acetate) onto a movement area of an airport (particularly onto a runway, taxiway or apron) by means of a self-propelled spray vehicle, wherein the spray vehicle comprises a control unit and a spray device, and the control unit is configured to activate and deactivate the spraying of the de-icer by the spray device, comprises the following steps: Driving into a first section and a second section of the movement area with the spray vehicle, wherein the first section is driven over in a first primary driving period and the second section in a second primary driving period, and spraying the de-icer onto the first section during the first primary driving period and defining a first primary spraying time assigned to the first section and lying within the first primary driving period, and spraying the de-icer onto the second section during the second primary driving period and defining a second primary spraying time assigned to the second section and lying within the second primary driving period, providing the first primary spraying time assigned to the first section and the second primary spraying time assigned to the second section in the control unit,Providing a first de-icer removal time value assigned to the first section and a second de-icer removal time value assigned to the second section in the control unit, re-entering the first section at a first secondary entry time and re-entering the second section at a second secondary entry time with the spray vehicle, detecting the re-entry into the respective section by the control unit and providing the first secondary entry time assigned to the first section and the second secondary entry time assigned to the second section in the control unit, and activating a re-spray of the de-icer onto the respective section of the movement area if the respective primary spray time has elapsed by more than the respective de-icer removal time value at the respective secondary entry time.

[0013] In this way, a unique combination of advantages can be achieved through a synergistic interaction of the features according to the invention, so that, as a result, a new application of de-icer to the respective section only takes place when the "local" de-icer degradation time value of the respective section has already elapsed since the previous de-icer application and thus the local de-icer concentration on the respective section has fallen below a defined limit.

[0014] The invention makes this possible by, on the one hand, allowing a de-icer removal time value to be specified (or provided) specifically for each section and, on the other hand, preventing the de-icer from being applied too frequently by considering individually for each section how long ago the de-icer was last sprayed there.

[0015] For this purpose, the movement area of the airfield is divided into different sections, it being immediately clear to the person skilled in the art that the method according to the invention is described and claimed for two sections for reasons of clarity, but can easily and analogously be transferred and applied to a significantly higher number of different sections (e.g. several hundred or several thousand different sections).

[0016] Typically, the longitudinal direction of the section is determined by the direction of travel of the sprayer, while the transverse direction of the section is determined by the spray width of the sprayer transverse to the direction of travel.

[0017] The respective extension of the individual sections in the longitudinal direction can be specified individually and depends on the desired granularity or accuracy of the section detection. Section sizes in the order of magnitude of a few square meters to several tens or several hundred square meters have proven to be particularly advantageous. It can be useful and simplify the implementation of the method according to the invention if the sections either (all) have the same extension in their longitudinal direction or if the extension of the sections in the longitudinal direction is predetermined by the distance that the spray vehicle covers in a predetermined time interval (e.g. within one second or one minute). The movement area to be sprayed with the de-icer is thus divided into various sections with defined positions or locations.

[0018] The spray vehicle drives over each section during a driving period. The first driving over of a section takes place during the so-called primary driving period. During this first driving over of a section, i.e. during the respective primary driving period, de-icer is sprayed onto the respective section. A point in time within each primary driving period is defined as the respective primary spraying time and assigned to the corresponding section. Different definitions can be used here: For example, it is conceivable that the beginning, the end, or an average value of the respective primary driving period is defined as the respective primary spraying time.

[0019] Furthermore, each section is assigned a section-specific de-icer removal time value, which indicates (or estimates) how long it is expected to take until the concentration of the applied de-icer on the surface of the respective section of the movement area is reduced to such an extent that a new application (spraying) of de-icer is indicated.

[0020] The de-icer removal time value of a section can depend on the current weather conditions (in particular the intensity of solar radiation, wind speed, temperature and precipitation), the location which determines the microclimate of the section (with shading effects and lower wind speeds due to buildings such as terminals and hangars in the immediate vicinity of the respective section playing a role), legal or airport-internal requirements and different safety-related requirements for different types of movement areas (e.g. the safety-related requirements for a runway differ from those for the apron).

[0021] The possibility of providing section-specific de-icer removal time values allows these various influencing factors to be taken into account on a section-specific basis.

[0022] By combining these features of the invention described above, it is possible to determine section-specifically and automatically when and where de-icer should be sprayed again in order to ensure that de-icer is applied as evenly and as precisely as possible.

[0023] In the following, some aspects of the method according to the invention will be discussed in more detail: The terms "primary overrun period," "primary spray time," "deicer de-icer time value," and "secondary entry time" are each assigned to one of the sections, either the first section or the second section. To more concisely express the respective assignment of the terms to the first or second section, the words "first" or "second" are prefixed to the terms to indicate the respective assignment. In this way, for example, the phrase "the first primary overrun period" indicates that it is the primary overrun period assigned to the first section, while the phrase "the second secondary entry time" indicates that it is the secondary entry time assigned to the second section.

[0024] A self-propelled spray vehicle is a spray vehicle with a drive unit that can be controlled by a human driver, remotely or autonomously along a route across an airport's movement area in one direction.

[0025] The spraying device of the spray vehicle typically comprises a de-icer tank in which the liquid moving area de-icer is stored, several spray nozzles by means of which the moving area de-icer can be sprayed onto the moving area over a spray width extending transversely to the direction of travel, and a de-icer pump by means of which the moving area de-icer can be conveyed from the de-icer tank to the spray nozzles.

[0026] If the spray device is activated, the spraying of moving area de-icer onto the moving area is started via the spray nozzles (in particular, by starting the de-icer pump) and continues as long as the spray device is activated. Deactivating the spray device stops the spraying of moving area de-icer onto the moving area (in particular, by stopping the de-icer pump).

[0027] In the method according to the invention, in order to determine whether a second spraying of de-icer on a section is (already) indicated, the respective first spraying time and the time at which the spray vehicle enters the respective section for the second time are considered.

[0028] At this point, it should be explicitly pointed out that the procedure is of course also suitable in an analogous manner for determining whether a third, fourth, fifth or nth spraying of de-icer is indicated.

[0029] In this case, for each section, it is not the first spraying time that is to be considered, but rather the last (i.e. the least recent) spraying time and the time at which the spraying vehicle subsequently re-enters the respective section.

[0030] This can be achieved in particular by carrying out the following steps after the re-spraying of the de-icer on the respective section has been activated and thus the de-icer is sprayed during a secondary crossing period: Defining a secondary spraying time assigned to the respective section and lying within the respective secondary crossing period, overwriting the previous primary spraying time (of the respective section) with the secondary spraying time (of the respective section), recording a future, renewed entry into the respective section as the secondary entry time.

[0031] According to a preferred embodiment of the method according to the invention, the first and second de-icer removal time values are identical or different.

[0032] Assigning identical de-icer removal time values to each section can reduce the complexity of implementing the procedure. However, assigning different de-icer removal time values to each section allows for section-specific influences to be mapped, thus further improving the procedure, particularly with regard to resource efficiency and flight safety.

[0033] Furthermore, according to another preferred embodiment, it can be provided that the de-icer removal time values are provided in that the de-icer removal time values can be freely specified by an operator.

[0034] The operator could, in particular, be a driver who controls or remotely controls the spray vehicle. It is also conceivable that the operator could be a fleet manager responsible for de-icing operations at the airport. This allows the operator's individual experience regarding de-icer removal times to be taken into account.

[0035] According to another preferred embodiment of the invention, it can be provided that the de-icer removal time values are provided by the de-icer removal time values being determined as a function of current weather conditions (in particular depending on a current temperature, a current wind speed, a current amount of precipitation and / or a current solar radiation intensity), forecast weather conditions (in particular depending on a forecast temperature, a forecast wind speed, a forecast amount of precipitation and / or a forecast solar radiation intensity) and / or a forecast movement area use intensity.

[0036] Section-specific current and / or forecast weather conditions can serve as input parameters to determine the respective de-icer de-icing time values for the individual sections based on a mathematical relationship. This allows, for example, to consider that higher wind speeds, higher temperatures, and higher solar radiation intensity each contribute to faster evaporation of the moving area de-icer, or that greater precipitation contributes to faster dilution of the moving area de-icer, thus leading to a shorter de-icer de-icing time value.

[0037] Similarly, it can be considered that increased movement area usage intensity can contribute to faster evaporation or removal of the movement area de-icer. The movement area usage intensity of a section describes how frequently and in what way the respective section of the movement area is used within a defined time interval—for example, how often aircraft take off and land on a particular section of a runway.

[0038] It can advantageously be provided that the de-icer removal time values are provided by the de-icer removal time values being input into an input unit of the spray vehicle that is operatively connected to the control unit.

[0039] This makes it particularly easy to enter the de-icer removal time values by an operator in the spray vehicle.

[0040] Alternatively or additionally, it can be provided that the de-icer removal time values are provided in that the de-icer removal time values can be received by a communication interface of the spray vehicle that is operatively connected to the control unit.

[0041] This means that the de-icer removal time values can be specified particularly easily, especially by a central fleet management office, and transmitted to the spray vehicle.

[0042] The invention is further manifested in the control device according to the invention according to claim 7, the computer program product according to the invention according to claim 8 and the spray vehicle according to the invention according to claim 9.

[0043] The control device according to the invention is designed to activate and deactivate the spraying of a moving area de-icer by a spraying device of a spray vehicle and to carry out the following steps of the method according to the invention: Providing the first primary spray time assigned to the first section and the second primary spray time assigned to the second section in the control unit, providing a first de-icer removal time value assigned to the first section and a second de-icer removal time value assigned to the second section in the control unit, detecting the re-entry into the respective section by the control unit and providing the first secondary entry time assigned to the first section and the secondary entry time assigned to the second section in the control unit, and activating a re-spray of the de-icer onto the respective section of the movement area if, at the respective secondary entry time, the respective primary spray time has elapsed by more than the respective de-icer removal time value.

[0044] The computer program product according to the invention comprises instructions which, when executed by a control device according to the invention, cause the control device to carry out the method steps according to claim 7.

[0045] The spray vehicle according to the invention comprises a spray device and a control unit according to the invention.

[0046] The invention is explained in more detail below using an exemplary embodiment. Fig. 1 is a schematic plan view of a spray vehicle according to the invention, Fig. 2A - The spray vehicle according to the invention when driving over a movement area with two sections at different times, and Fig. 3A - Three representations of the time sequence of driving over the sections by the spray vehicle according to the Figures 2A to 2D .

[0047] Figure 1is a schematic plan view of a self-propelled spray vehicle 1 according to the invention with a spray device 2, a control unit 3 and wheels 4. The spray device 2 comprises a de-icer tank 5 in which liquid organic de-icer is stored, a spray boom 6 in which spray nozzles 7 are arranged, and a de-icer pump 8 by means of which the moving surface de-icer can be conveyed from the de-icer tank to the spray nozzles 7.

[0048] The control unit 3 is configured to activate the spraying of the de-icer by the spray device 2 by activating the de-icer pump 8.

[0049] The spray vehicle can be moved in a direction of travel 9. The spray boom 6 with the spray nozzles 7 extends transversely to the direction of travel 9.

[0050] If the spray device 2 is activated by the control unit 3, the de-icer pump 8 conveys the de-icer to the spray nozzles 7, via which the de-icer is then sprayed onto a movement area 11 over a spray width 10 extending transversely to the direction of travel 9.

[0051] The spray vehicle 1 further comprises a position detection device 12 operatively connected to the control unit 3. The position detection device 12 is suitable for detecting the current position of the spray vehicle 1 and transmitting it to the control unit 3.

[0052] Based on the Figures 2A to 2D and 3A and 3B, the method according to the invention will be explained in detail by way of example.

[0053] Shown in the Figures 2A to 2D the spray vehicle 1 according to Figure 1and a first section 13 and a second section 14 of a movement area 11 of an airport. Both sections 13, 14 are part of a runway of the airport and each have an identical section length 15 and an identical section width 16, which corresponds to the spray width 10 of the spray vehicle 1. In the present example, the section length 15 is selected such that the spray vehicle 1, moving at a target speed, requires exactly one minute to cover the section length 15 and thus to pass through a section 13, 14.

[0054] The position and extent of the two sections 13, 14 are stored in the control unit 3 (in particular in the memory unit). The control unit 3 is further capable of detecting, using the current position of the spray vehicle 1 transmitted by the position detection device 12, which section 13, 14 of the movement area the spray vehicle 1 is currently entering or which section 13, 14 the spray vehicle 1 is currently driving over.

[0055] The Figures 3A and 3B illustrate the time sequence of crossing the first section (see Figure 3A ) or the second section (see Figure 3B ) by the spray vehicle 1 in accordance with the Figures 2A to 2D The x-axis represents the elapsed time t in minutes.

[0056] As in Figure 2A, the spray vehicle 1 has already entered the first section 13 of the runway and is crossing it. The spray vehicle 1 crosses the first section 13 during a first primary crossing period 1PÜZ, which here lasts from t = 0 to t = 1 min, and sprays de-icer onto the first section 13 during this period. The first primary crossing period 1PÜZ is recorded in the control unit and a first primary spraying time 1PAZ is defined. A definition is used according to which the start of the respective primary crossing period determines the respective primary spraying time. The first primary spraying time 1PAZ is therefore t = 0 min. See also Figure 3A .

[0057] The second section 14 is, as in Figure 2Brepresents, is not driven over for the first time by spray vehicle 1 and sprayed with de-icer immediately after the first section 13, but only in the second primary overrun period 2PÜZ between t = 7 min and t = 8 min. This can be due, for example, to the fact that the spray vehicle had to leave the runway after driving over the first section 13 due to an approaching aircraft and thus had to abort the spraying process. The second primary spraying time 2PAZ is therefore t = 7 min (cf. Figure 3B ).

[0058] The first primary spray timing 1PAZ (assigned to the first section) and the second primary spray timing 2PAZ (assigned to the second section) are each provided in the control unit 3.

[0059] An operator assigns the de-icer removal time value EZ = 10 min to each of the two sections 13 and 14. Both sections thus have identical de-icer removal time values EZ. The first and second de-icer removal time values EZ = 10 min assigned to the first section 13 and the second section 14, respectively, are provided in control unit 3.

[0060] Then the spray vehicle 1 drives, as shown in the Figures 2C and 2D As outlined, it enters the two sections 13, 14 of the runway a second time. In the present example, the entry time is defined by the spray boom 6 of the spray device 3 entering (entering) the respective section 13, 14.

[0061] The spray vehicle 1 drives according to Figure 2Cinto the second section 14 for the second (repeated) time at time t = 12 min. The second secondary entry time 2SEZ (assigned to the second section) is therefore t = 12 min. This second entry into the second section 14 is detected by the control unit 3, and the second secondary entry time 2SEZ is provided in the control unit 3. The control unit now checks whether, in the second secondary entry time 2SEZ t = 12 min, more than the respective de-icer removal time value EZ = 10 min has elapsed since the second primary spraying time 2PAZ t = 7 min. This is not the case here, because only 5 min have elapsed since the second primary spraying time 2PAZ t = 7 min in the second secondary entry time 2SEZ t = 12 min. A renewed spraying of the de-icer onto the second section is therefore not activated by the control unit (see Figure 3B ).

[0062] However, if the spray vehicle 1, as in Figure 2Dshown, enters the first section 13 of the runway for the second time at time t = 13 min, a new spraying of de-icer is activated because in the first section since the first primary spraying time 1PAZ t = 0 min, 13 min have already elapsed and thus more than the de-icer removal time value EZ = 10 min.

[0063] The individual steps leading to the activation of the re-spray are outlined in detail below: The first secondary entry time 1SEZ (assigned to the first section) is t = 13 min. This second entry into the first section 13 is detected by control unit 3 and the first secondary entry time 1SEZ is provided in control unit 3. Control unit 3 now checks whether, in the first secondary entry time 1SEZ t = 13 min, the first primary spray time 1PAZ t = 0 min has elapsed by more than the de-icer removal time value EZ = 10 min. This is the case, because 13 minutes have already passed since the first primary spray time 1PAZ t = 0 min in the first secondary entry time 1SEZ t = 13 min. The re-spraying of the de-icer onto the first section 13 is thus activated by control unit 3. List of reference symbols

[0064] Spray vehicle 1 Spray device 2 control unit 3 Wheels 4 De-icer tank 5 Spray boom 6 Spray nozzles 7 De-icer pump 8 Direction of travel 9 Spray width 10 Movement area 11 Position detection device 12 first section 13 second section 14 Section length 15 Section width 16 first primary crossing period 1PÜZ first primary spray time 1PAZ second primary crossing period 2PÜZ second primary spray time 2PAZ De-icer degradation time value EZ first secondary entry time 1SEZ second secondary entry point 2SEZ

Claims

1. Method for de-icing by spraying a liquid organic de-icer, which is in particular a solution based on glycol, urea, formate and / or acetate, onto a movement area (11) of an airfield, in particular onto a runway, a taxiway or an apron, by means of a self-propelled spraying vehicle, wherein the spraying vehicle (1) comprises a control unit (3) and a spraying device (2), and the control unit (3) is set up to activate and deactivate the spraying of the de-icer by the spraying device (2), with the following steps: - driving into a first section (13) and a second section (14) of the movement area (11) with the spraying vehicle (1), the first section (13) being driven over in a first primary drive-over period (1PÜZ) and the second section (14) being driven over in a second primary drive-over period (2PÜZ), and - spraying the de-icer onto the first section (13) during the first primary drive-over period (1PÜZ) and defining a first primary spraying time (1PAZ) assigned to the first section and lying within the first primary drive-over period, and - spraying the de-icer onto the second section (14) during the second primary drive-over period (2PÜZ) and defining a second primary spraying time (2PAZ) assigned to the second section and lying within the second primary drive-over period, - providing the first primary spraying time (1PAZ) assigned to the first section (13) and the second primary spraying time (2PAZ) assigned to the second section (14) in the control unit (3), - providing a first de-icer degradation time value (EZ) assigned to the first section (13) and a second de-icer degradation time value (EZ) assigned to the second section (14) in the control unit (3), - re-entering into the first section (13) at a first secondary re-entering time (1SEZ) and re-entering into the second section (14) at a second secondary re-entering time (2SEZ) with the spraying vehicle (1) - detecting of the re-entering into the respective section (13) by the control unit (3) and providing of the first secondary re-entering time (1SEZ) assigned to the first section (13) and the second secondary re-entering time (2SEZ) assigned to the second section (14) in the control unit (3), and - activating a renewed spraying of the de-icer onto the respective section (13, 14) of the movement area (11) if the respective primary spraying time (1PAZ, 2PAZ) has elapsed by more than the respective de-icer degradation time value (EZ) at the respective secondary spraying time (1SEZ, 2SEZ).

2. The method according to claim 1, wherein the first and second de-icer degradation time values (EZ) are identical or different.

3. Method according to one of the preceding claims, wherein the de-icer degradation time values (EZ) are provided by allowing the de-icer degradation time values (EZ) to be freely preset by an operator.

4. Method according to one of the preceding claims, wherein the de-icer degradation time values (EZ) are provided by setting the de-icer degradation time values (EZ) as a function of - current weather conditions, in particular as a function of a current temperature, a current wind speed, a current amount of precipitation and / or a current intensity of solar radiation, - predicted weather conditions, in particular as a function of a predicted temperature, a predicted wind speed, a predicted amount of precipitation and / or a predicted intensity of solar radiation, and / or - of a predicted movement area utilisation intensity.

5. Method according to one of the preceding claims, wherein the de-icer degradation time values (EZ) are provided by entering the de-icer degradation time values (EZ) into an input unit of the spraying vehicle (1) which is operatively connected to the control unit (3).

6. Method according to one of the preceding claims, wherein the de-icer degradation time values (EZ) are provided by receiving the de-icer degradation time values (EZ) by a communication interface of the spraying vehicle (1) which is operatively connected to the control unit (3).

7. A control unit (3) configured to activate and deactivate the spraying of a de-icer by a spraying device (2) of a spraying vehicle (1) and to perform the following steps of the method according to claim 1: - Providing the first primary spraying time (1PAZ) assigned to the first section (13) and the second primary spraying time (2PAZ) assigned to the second section (14) in the control unit (3), - providing a first de-icer degradation time value (EZ) assigned to the first section (13) and a second de-icer degradation time value (EZ) assigned to the second section (14) in the control unit (3), - detecting of the re-entering into the respective section (13) by the control unit (3) and providing of the first secondary re-entering time (1SEZ) assigned to the first section (13) and the second secondary re-entering time (2SEZ) assigned to the second section (14) in the control unit (3), and - activating a renewed spraying of the de-icer onto the respective section (13, 14) of the movement area (11) if the respective primary spraying time (1PAZ, 2PAZ) has elapsed by more than the respective de-icer degradation time value (EZ) at the respective secondary spraying time (1SEZ, 2SEZ).

8. A computer program product comprising instructions which, when executed by a control unit (3) according to claim 7, cause the control unit (3) to perform the method steps according to claim 7.

9. Spraying vehicle (1) comprising a spraying device (2) and a control unit (3) according to claim 7.

Images