DE102022130348A1 - CONTROL DEVICE AND METHOD FOR CONTROLLING A COMPRESSED AIR SYSTEM - Google Patents

Abstract

Control device (100) and method for controlling a compressed air system (10) of a vehicle (1). The compressed air system (10) comprises a compressor (12) configured to be powered by an energy storage device (5), a tank (14), and a supply system (16) configured to supply compressed air from the To deliver the tank to a plurality of air consumers (21, 22, 23, 24). The method includes, when there is an indication that a current state of charge of the energy storage device (5) is equal to or below a state of charge threshold, reducing a minimum target pressure (P_cutin) to be maintained in the tank (14) by the compressor (12). , to a first predefined target pressure threshold (P_cutin_critial), and setting a target speed of the compressor (12) to a speed defined by a predetermined efficiency curve of the compressor (12). The efficiency curve represents a specific energy consumption per unit mass of the air compressed by the compressor (12) and is dependent on the first predefined target pressure threshold value (P_cutin_critial).

Description

TECHNICAL AREA

The present disclosure generally relates to a method for controlling a compressed air system of a vehicle. The present disclosure also generally relates to a controller configured to control a compressed air system of a vehicle. The present disclosure also generally relates to a computer program, a computer-readable medium, and a vehicle.

BACKGROUND

Vehicles with electric drive systems are becoming increasingly popular as part of efforts to find more environmentally friendly solutions. However, range anxiety and range awareness are increasing as the number and types of electrified vehicles increase. The conversion of vehicles to electric propulsion also means that various other systems of the vehicle, which previously may have been powered by the combustion engine, are now being electrified and thus also using electricity from the energy storage system. An example of such a system is a compressed air system where the compressor is powered by the energy storage. Traditionally, compressed air in vehicles has often been considered essentially free energy, since its generation has traditionally been done by a compressor that uses the energy inherent in the internal combustion engine. However, when a compressor is powered by the energy storage device (which also powers a propulsion unit of the vehicle), this has a direct impact on the potential range of the vehicle before the energy storage device needs to be recharged.

US 8,718,848 B2 discloses a system and method for using an electric air charging system to maintain a hybrid utility vehicle battery in a desired charge range. The method includes, if the determined state of charge is less than or equal to a state of charge (SOC) threshold, reducing the turn-on and turn-off pressure thresholds for the air compressor and reducing the compressor speed. This controls the air compressor to build up air pressure more slowly to a lower pressure threshold. This should result in the compressor using less energy and maintaining the battery charge level. However, reducing the compressor speed and building up pressure more slowly is not the most energy efficient solution in all situations.

U.S. 10,173,616 discloses a compressed air system having an electric drive motor that can be controlled for variable speed and a compressor coupled to be driven by the electric drive motor. A controller controls the electric drive motor to determine the speed of the electric drive motor so that during filling of an air tank when the pressure in the air tank is between a minimum setpoint, _{P_cutin} , and a higher cut-off pressure, _{P_cutoff} , the controller changes the speed of the compressor in such a way that the specific power consumption per unit air mass is reduced. The document further describes that additional pressure intervals can be defined for the air tank, in which the compressor is controlled differently. If the pressure is below a minimum level, P _{_cutin_critical} , the compressor can operate at the highest possible speed so that the pressure rises above this minimum level as quickly as possible. If the pressure is between the minimum value P _{_cutin_critical} and the target value P _{_cutin} , the speed of the compressor can be determined by the control device based on various signals (e.g. state of the accelerator pedal, speed of the vehicle, temperature of the power supply or state of the electrical supply). become. The system in such a case can operate in air consumption mode, so that the consumed amount of air is replenished into the system, or in compressor operation mode, in order to achieve complete replenishment within a time frame in which the compressor can operate continuously. The system described above allows the power consumption required to drive the compressor to be lowest between the normal set point, P _{_cutin} , and a higher cut-off pressure, P _{_cutoff} , but at other pressure intervals the compressor is driven in a different way to vary to achieve different desired results depending on the pressure in the air tank.

SUMMARY

The aim of the present invention is to increase the range of a vehicle in situations in which the state of charge of an energy store in the vehicle can be considered to be low.

The aim is achieved by the subject-matter of the attached independent claim(s).

• - Reduzieren eines minimalen Solldruckes (P_{_cutin}), der in dem Tank durch den Kompressor aufrechterhalten werden soll, auf einen ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}), und
• - Einstellen einer Solldrehzahl des Kompressors auf eine Drehzahl, die gleich oder innerhalb eines definierten Intervalls um die energieeffizienteste Drehzahl des Kompressors herum ist, wie sie durch eine vorbestimmte Effizienzkennlinie des Kompressors definiert ist, wenn sie nicht bereits dieser Drehzahl entspricht, wobei die Effizienzkennlinie einen spezifischen Energieverbrauch pro Masseneinheit der durch den Kompressor komprimierten Luft darstellt und von dem ersten vordefinierten Solldruckschwellenwert (P_{_cutin-critial}) abhängig ist.

According to the present disclosure, a method for controlling a compressed air system of a vehicle is provided. The method is carried out by a control device. The Compressed air system includes an electrically powered compressor configured to be powered by an energy storage device of the vehicle, a tank configured to store compressed air generated by the compressor, and a supply system configured to supply compressed air from the To deliver tank to a plurality of air consumers of the vehicle. The method includes when there is an indication that a current state of charge of the energy storage device is equal to or below a state of charge threshold:

• - reducing a minimum target pressure (P _{_cutin} ) to be maintained in the tank by the compressor to a first predefined target pressure threshold (P _{_cutin_critial} ), and
• - setting a target compressor speed to a speed equal to or within a defined interval of the most energy efficient compressor speed as defined by a predetermined compressor efficiency curve, if not already equal to that speed, the efficiency curve having a specific represents energy consumption per unit mass of air compressed by the compressor and is dependent on the first predefined desired pressure threshold (P _{_cutin-critical} ).

The present method significantly reduces the power consumption of the energy storage device by the compressor, which in turn increases the possible driving range of the vehicle until the energy storage device is charged. More specifically, reducing the minimum target pressure (P _{_cutin} ) to be maintained by the compressor in the tank to a first predefined target pressure threshold (P _{_cutin_critial} ) results in maintaining a lower minimum pressure compared to a minimum pressure to be maintained in the tank normally aimed at, and the compressor consequently less air to compress. In addition, setting the compressor target speed to a speed that is equal to or at least close to the most energy efficient speed as defined by a predetermined compressor efficiency curve, where the efficiency curve represents the specific energy consumption per unit mass of air compressed by the compressor and from depends on the first predefined target pressure threshold (P _{_cutin_critial} ), to a more efficient operation of the compressor. This can reduce the power consumption of the energy storage device to maintain an acceptable pressure in the tank.

The method may further include reducing allowable air consumption from the tank by at least a first air consumer of the plurality of air consumers that is not a braking system configured to brake the vehicle. This can reduce the amount of compressed air that needs to be generated by the compressor. This leads to lower energy consumption by the compressor and thus to an increase in the possible driving range of the vehicle.

The first air consumer mentioned above may be selected from the group consisting of a vehicle air suspension system, an auxiliary system connected to the air pressure system, a low-entry mode system, and a cab suspension system. Reducing the permissible air consumption by such a first air consumer does not impair the operational safety of the vehicle and can therefore be an acceptable compromise in order to increase the driving range if necessary.

The compressed air system may also include an air drying cartridge configured to dry the air compressed by the compressor before it enters the tank, the air drying cartridge being configured to be regenerated using compressed air from the tank. In this case, the method may also include preventing regeneration of the air dryer cartridge. This eliminates the consumption of compressed air from the air drying cartridge, which in turn can reduce the amount of compressed air that needs to be generated by the compressor. As a result, the compressor consumes less energy from the energy storage device.

The first predefined target pressure threshold (P _{_cutin_critial} ) may represent a minimum pressure to be maintained in the tank to ensure that at least a second air consumer from the plurality of air consumers is supplied with sufficient air pressure so that the second air consumer can be fully operated, wherein the second air consumer is essential for the operational safety of the vehicle. Alternatively, the first predefined target pressure threshold (P _{_cutin_critial} ) may represent a minimum required pressure defined by government regulations and/or manufacturer recommendations.

The second air consumer mentioned above may be a braking system configured to brake the vehicle. Preferably, the second air consumer is a braking system configured to brake the vehicle using the service brakes.

The above state of charge threshold may depend on an estimated state of charge required for the vehicle to reach a geographic location where the energy storage device may be charged. In other words, the state of charge threshold may vary depending on the particular circumstances, e.g. B. the distance that the vehicle needs to reach a place where the energy storage device can be charged. The method described here is particularly suitable for situations in which it is assumed that the current state of charge of the energy storage device is insufficient or could be sufficient for the vehicle to reach a position for an impending charging process. Alternatively, the aforementioned state of charge threshold may be a fixed minimum state of charge threshold of the energy storage device.

The method may further include where the minimum target pressure ( _{P_cutin} ) is reduced, a maximum target pressure ( _{P_cutoff} ) at which the compressor should temporarily cease air compression is also reduced to a second predefined target pressure threshold ( _{P_cutoff_low} ). This can reduce the risk of inappropriate power consumption by the compressor producing more compressed air than necessary.

If it is determined that the compressor can be powered by a power supply other than the energy storage device, the method may further include powering the compressor from said power supply. As a result, the compressor does not have to be driven by the energy storage device and thus does not contribute to its discharge.

The power supply device mentioned above, other than the energy storage device, may suitably be a regenerative brake of the vehicle. In this way, the energy generated during regenerative braking of the vehicle can be used efficiently by the compressor.

The compressor may be operated at a maximum allowable speed that depends on the configuration of the compressor and/or the power available to the compressor when powered by the power supply. This allows the compressor to generate more compressed air, which is stored in the tank as a buffer. Such a buffer can further reduce the power consumption of the compressor from the energy storage device when the compressor can no longer be powered by the power supply device and therefore needs to be powered by the energy storage device.

The present disclosure further relates to a computer program having instructions that, when executed by a controller, cause the controller to perform the method described above.

The present disclosure further relates to a computer-readable medium having instructions that, when executed by a controller, cause the controller to perform the method described above.

• - Reduzieren eines minimalen Solldruckes (P_{_cutin}), der in dem Tank durch den Kompressor aufrechterhalten werden soll, auf einen ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}), und
• - Einstellen einer Solldrehzahl des Kompressors auf eine Drehzahl, die gleich oder innerhalb eines definierten Intervalls um die energieeffizienteste Drehzahl des Kompressors herum ist, wie sie durch eine vorbestimmte Effizienzkennlinie des Kompressors definiert ist, wenn sie nicht bereits dieser Drehzahl entspricht, wobei die Effizienzkennlinie einen spezifischen Energieverbrauch pro Masseneinheit der durch den Kompressor komprimierten Luft darstellt und von dem ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}) abhängig ist.

Die Steuervorrichtung bietet die gleichen Vorteile, wie sie oben im Hinblick auf das entsprechende Verfahren zum Steuern eines Druckluftsystems eines Fahrzeugs beschrieben wurden.Additionally, the present disclosure provides a controller configured to control a compressed air system of a vehicle. The compressed air system includes an electrically powered compressor configured to be powered by an energy storage device of the vehicle, a tank configured to store compressed air generated by the compressor, and a supply system configured to extract compressed air the tank to a plurality of air consumers of the vehicle. The controller is configured to, when there is an indication that a current state of charge of the energy storage device is equal to or below a state of charge threshold:

• - reducing a minimum target pressure (P _{_cutin} ) to be maintained in the tank by the compressor to a first predefined target pressure threshold (P _{_cutin_critial} ), and
• - setting a target compressor speed to a speed equal to or within a defined interval of the most energy efficient compressor speed as defined by a predetermined compressor efficiency curve, if not already equal to that speed, the efficiency curve having a specific represents energy consumption per unit mass of air compressed by the compressor and is dependent on the first predefined target pressure threshold (P _{_cutin_critial} ).

The control device offers the same advantages as described above with regard to the corresponding method for controlling a compressed air system of a vehicle.

The controller may further be configured to determine the allowable air consumption of at least a first air consumer of the plurality of air consumers that is not a first braking system configured to brake the vehicle is reduced.

The present disclosure further provides a vehicle including a compressed air system and the controller described above. The vehicle may be a land based heavy vehicle such as a truck or a bus. Additionally, the vehicle may be a partially or fully electrically powered vehicle.

character list

• 1 schematically shows a side view of an example vehicle,
• 2 shows schematically an example of a compressed air system of a vehicle,
• 3 12 is a flow chart that schematically illustrates an exemplary embodiment of the method for controlling a compressed air system according to the present disclosure.
• 4 shows schematically an example of a predetermined efficiency characteristic of a compressor of a compressed air system of a vehicle, and
• 5 FIG. 1 shows schematically a device that can form, comprise or be part of a control device for controlling a compressed air system of a vehicle.

DETAILED DESCRIPTION

The invention is described in more detail below with reference to exemplary embodiments and the accompanying drawings. However, the invention is not limited to the exemplary embodiments discussed and/or shown in the drawings, but may be varied within the scope of the appended claims. In addition, the drawings are not to be considered to scale as some features may be exaggerated in order to better illustrate the invention or its features.

The term "vehicle air suspension system" in the present disclosure means the air suspension system of the chassis of the vehicle. The term "air suspension system of the vehicle" used here is therefore not to be confused with other air suspension systems that may be present in the vehicle, such as e.g. B. a cab suspension system, a seat suspension system or the like.

Additionally, in the present disclosure, the term “auxiliary system” is intended to mean a system that is installed on the vehicle by a customer or user of the vehicle, or by a body builder. As in the automotive industry, manufacturers of heavy vehicles may produce vehicles that are intended for delivery to end customers or end users of the vehicles. However, it is also common for heavy vehicles to be only partially manufactured by the vehicle manufacturer (typically at least the chassis and powertrain and the vehicle's internal systems are produced by the vehicle manufacturer) and then completed by a third party to meet specific requirements of the end customer or user. A coachbuilder is one such third party. For example, a vehicle manufacturer may produce a powertrain for a vehicle from which a third party completes the vehicle to be used as a mobile home, fire truck, ambulance, cement mixer, crane truck, refrigerated truck, or the like. Also z. B. drive trains for buses are produced by the vehicle manufacturer with little or no structure in order to complete the vehicle with a later structure by a body manufacturer.

It is clear from the above that some vehicle air consumers may constitute ancillary systems when fitted to the vehicle by a customer, user or bodybuilder, but they may also be fitted to the vehicle by the vehicle manufacturer and in that case not as an ancillary system are valid. An example of an air consumer that may or may not be an ancillary system, depending on who installed the air consumer in the vehicle, is a pneumatic actuator used to open and close the vehicle's doors. Other examples include cab suspension systems, seat suspension systems and low-entry systems. It should be clarified here that the term "low-entry system" means a system that makes it possible to lower a vehicle temporarily, e.g. B. to facilitate boarding a passenger by the vehicle goes to its knees.

The present disclosure provides a method for controlling a compressed air system of a vehicle, executed by a controller. The compressed air system includes an electrically powered compressor configured to be powered by an energy storage device of the vehicle. More specifically, the compressor is configured to be powered by an energy storage device Energy is supplied, wherein the energy storage device is also used to operate a drive unit of the vehicle. The compressed air system further includes a tank configured to store compressed air generated by the compressor. In addition, the compressed air system includes a supply system that is configured to deliver compressed air from the tank to a plurality of air consumers of the vehicle. One of the multiple air consumers is typically a braking system configured to brake the vehicle using the vehicle's service (ie, wheel) brakes. The compressed air system's compressor is configured to maintain a desired pressure in the tank by beginning to compress air when the pressure drops to a minimum set pressure ( _{P_cutin} ). In order not to excessively increase the pressure in the tank, the compressor is configured in such a way that it is switched off temporarily when a maximum target pressure (P _{_cutoff} ) is reached in the tank.

• - Reduzieren eines minimalen Solldruckes (P_{_cutin}), der in dem Tank durch den Kompressor aufrechterhalten werden soll, auf einen ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}) (falls er nicht bereits dem ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}) entspricht), und
• - Einstellen einer Solldrehzahl des Kompressors auf eine eingestellte Solldrehzahl, die gleich oder innerhalb eines definierten Intervalls um die energieeffizienteste Drehzahl des Kompressors herum liegt, wie sie durch eine vorbestimmte Effizienzcharakteristik (Wirkungsgradkennlinie) des Kompressors definiert ist, wobei die Effizienzcharakteristik den spezifischen Leistungsverbrauch pro Masseneinheit der durch den Kompressor komprimierten Luft darstellt und von dem ersten vordefinierten Solldruckschwellenwert (P_{_cutin_critial}) abhängig ist.

The method for controlling the compressed air system according to the present disclosure, when there is an indication that a current state of charge of the energy storage device is at or below a state of charge threshold, includes the following steps:

• - reducing a minimum target pressure (P _{_cutin} ) to be maintained in the tank by the compressor to a first predefined target pressure threshold (P _{_cutin_critial} ) (if it does not already correspond to the first predefined target pressure threshold (P _{_cutin_critial} )), and
• - setting a target speed of the compressor to a set target speed equal to or within a defined interval of the most energy efficient speed of the compressor as defined by a predetermined efficiency characteristic (efficiency curve) of the compressor, the efficiency characteristic being the specific power consumption per unit mass of the represents air compressed by the compressor and is dependent on the first predefined target pressure threshold (P _{_cutin_critial} ).

It should be noted that in some situations the target compressor speed may already coincidentally correspond to such a set target speed which is equal to or within a certain interval of the most energy efficient compressor speed as defined by a predetermined efficiency curve defined by the predefined desired pressure threshold value (P _{_cutin_critial} ). In such cases, the target speed does not have to be adjusted, but can be kept at the current target speed. Alternatively, if the target speed does not correspond to the most energy efficient speed of the compressor, the target speed may be set to an adjusted target speed that is closer to the most energy efficient speed of the compressor as defined by the predetermined efficiency characteristic derived from the first predefined target pressure threshold ( _{P_cutin_critial} ) depends.

With the present method, the compressor is operated under the conditions of the predefined target pressure threshold ( _{P_cutin_critial} ) and a speed that is equal to or at least close to the most energy efficient speed of the compressor as defined by the predefined compressor efficiency curve.

Of course, the most energy-efficient result and thus the best driving range of the vehicle can be achieved if the target speed of the compressor is set to the most energy-efficient speed, which is defined by the given efficiency curve. However, some tolerance in the speed at which the compressor target speed is set may be acceptable. Therefore, as mentioned above, the target speed can be adjusted according to the method described here to a speed that is within a defined interval around the most energy-efficient speed that is defined by the predetermined efficiency characteristic. For example, the defined interval may be an interval ranging from -10% of the most energy efficient speed defined by the predetermined efficiency curve to +10% of the most energy efficient speed defined by the predetermined efficiency curve (including the end values of the range). In other words, the specified interval may be an interval of ±10% of the most energy efficient speed. Conveniently, the desired compressor speed is set to a speed which is within the interval of ±5% or ±3% (including full scale) of the most energy efficient compressor speed as defined by the given efficiency curve. Of course, other alternatives of the defined interval to which the setpoint speed of the compressor is set are also conceivable, e.g. B. from -5% of the most energy-efficient speed defined by the specified efficiency characteristic to +10% of the most energy-efficient speed defined by the specified efficiency characteristic or -10% of the most energy-efficient speed defined by the specified efficiency characteristic to +5% of the most energy-efficient speed defined by the specified efficiency characteristic . In addition, the defined interval at which the target compressor speed is set does not have to be determined by using a percentage of the most energy efficient speed as defined by the given efficiency curve is defined, but can alternatively also be defined by revolutions per minute. For example, the boundaries of the defined interval may be dictated by the most energy efficient speed defined by the predetermined features ±200 rpm, ±100 rpm, ±50 rpm, or ±20 rpm.

The predetermined efficiency curve (efficiency curve) of the compressor can typically be represented by an efficiency curve which represents the specific power consumption per unit mass of air compressed by the compressor and is dependent on the first predetermined desired pressure threshold value ( _{P_cutin_critial} ). In other words, the target speed of the compressor can be adjusted according to the present method to a speed that results in the lowest specific power per unit mass of the air compressed by the compressor for the compressor used and for the first predefined target pressure threshold value.

Reducing the minimum target pressure ( _{P_cutin} ) to be maintained by the compressor in the tank to the first predefined target pressure threshold ( _{P_cutin_critial} ) results in a lower pressure being maintained compared to a normally targeted minimum pressure to be maintained in the tank and the compressor consequently compressing less air must. In addition, the desired compressor speed is set at a speed that is at or at least close to the most energy efficient compressor speed as defined by a given compressor efficiency curve (where the efficiency characteristics/efficiency curve described above reflects the specific power consumption per unit mass of the Compressor compressed air and depend on the first predefined desired pressure threshold (P _{_cutin_critial} )), results in the compressor being operated more efficiently, which can reduce the power consumption of the energy storage device to maintain an acceptable pressure in the tank. For comparison, during normal operation of the compressed air system (ie, when the present method is not followed), the desired compressor speed is typically chosen depending on other factors, such as: B. the allowable time to reach a desired pressure in the tank and / or the noise generated by the compressor, and therefore may not be operated at the most energy efficient speed. With the present method, the energy consumption of the compressor is thus reduced through the combination of lower compressed air generation and more energy-efficient drive. As a result, less energy from the energy storage device is consumed by the compressor and can instead be used to power the vehicle, which in turn increases range.

In addition, the procedure described here compared to that in US 8,718,848 B2 The method described ensures that compressor power consumption is reduced in all possible situations when the current state of charge of the energy storage is equal to or lower than a desired state of charge, simply by reducing the speed of the compressor to build up pressure more slowly to a reduced setpoint pressure. This is accomplished by targeting the target speed to a speed that is equal to or at least close to the most energy efficient speed of the compressor for the minimum target tank pressure to be maintained by the compressor. In contrast, the previously proposed method can, in some situations, lead to an increase in the power consumption of the compressor, even though the compressor is used to build up a lower pressure in the tank than the normally desired pressure. In addition, an arbitrary reduction in compressor speed is a significantly worse solution than selecting the (proven) most energy-efficient speed for the compressor in question.

The method described herein may expediently further comprise a step in which, if it is indicated that a current state of charge of the energy storage device is equal to or below a state of charge threshold value, the permissible air consumption from the tank by at least a first air consumer of the plurality of air consumers is reduced, wherein this first consumer of air is not essential for safety when operating the vehicle. This can be achieved, for example, by controlling the supply system. An example of an air consumer that is essential to the operation of the vehicle is a braking system that is configured to brake the vehicle using service brakes of the vehicle (where the service brakes are pneumatically controlled). Therefore, the first air consumer should be a different air consumer than the braking system configured to brake the vehicle using the vehicle's service brakes. On some heavy vehicles, the service brakes may be relatively weak as other brakes (such as regenerative braking, retarders and/or exhaust brakes) take precedence. In such cases, an air consumer, e.g. B. in the form of an exhaust brake, are considered essential for the operation of the vehicle. However, in some cases it may be acceptable to display the allowable air consumption of an air consumer in the form of an Aus puff brake slightly to thereby rely more on the service brakes.

Another example of an air consumer that is important to safety in vehicle operation is a transmission system in which the shifting operations are performed through the use of pneumatic actuators. The ability to perform shifting operations is essential to the safety of vehicle operation. However, it may be possible to reduce the air consumption of the transmission system, for example by adjusting the shift limits in order to reduce the number of shifts. Therefore, such a transmission system is not considered herein to be essential to the safety of vehicle operation. However, it is advisable to reduce the permissible air consumption by such a transmission system only in very critical cases. In other words, the first air consumer for which the permissible air consumption from the tank is reduced is suitably a different air consumer than a transmission system in which the shifting operations are carried out through the use of pneumatic actuators.

In some cases, the step of reducing the allowable tank air consumption by the first air consumer may include reducing the first air consumer's tank air consumption to zero. In other words, the method can consist in preventing the consumption of air from the tank by the first air consumer of the plurality of air consumers.

The above-mentioned first air consumer of the plurality of air consumers may suitably be selected from the group consisting of a vehicle air suspension system, an auxiliary system connected to the air pressure system, a low-entry mode system, and a cab suspension system. Other examples of the first air consumer include a seat suspension system, a vehicle door opening and closing system, and a steering wheel position control system. In general, the air consumer that has the highest air consumption and is not essential to the operational safety of the vehicle is the vehicle's air suspension system. Therefore, the first air consumer can preferably be the air suspension system of the vehicle. Of course, the method may also include reducing the permissible in-tank air consumption of two or more of the plurality of air consumers, as long as these two or more air consumers are not essential to the safety of vehicle operation. These two or more air consumers can be selected in any combination from the above examples for the first air consumer. The method can include, for example, reducing the allowable air consumption of the vehicle's air suspension system and reducing the allowable air consumption of one or more auxiliary systems connected to the compressed air system.

In general, a compressed air system of the type described herein also includes an air drying cartridge configured to dry the air compressed by the compressor before it enters the tank. Such an air drying cartridge can be designed to be regenerated (i.e., removing moisture from the air drying cartridge) at appropriate times through the use of pressurized air from the tank. The purpose of regeneration is to reduce the risk of moisture in the compressed air system tank. The method according to the present disclosure may further include preventing such regeneration of the air dryer cartridge when there is an indication that a current state of charge of the energy storage device is equal to or below a threshold state of charge. This reduces the amount of air used from the tank, which means the compressor has to compress less air and thus reduces the energy consumption of the energy storage device. Although this increases the risk of moisture in the tank, this can be an acceptable compromise as this moisture can be removed later when the vehicle has reached a desired destination.

In one alternative, the first predefined target pressure threshold ( _{P_cutin_critial} ) described above represents a minimum pressure to be maintained in the tank to ensure that at least a second air consumer of the plurality of air consumers is supplied with sufficient air pressure to fully operate the second air consumer can, the second air consumer is essential for the operational safety of the vehicle. As can be seen from the disclosure above, the second air consumer may be a braking system configured to brake the vehicle. In particular, the second air consumer can be a braking system that is designed to brake the vehicle using the service brakes. According to a further alternative, the first predefined target pressure threshold value ( _{P_cutin_critial} ) represents a required minimum pressure, which is defined by legal requirements and/or manufacturer recommendations. Typically, such a required minimum pressure defined by statutory regulations and/or by manufacturer recommendations can be specified in such a way that that safe operation of the vehicle is ensured and therefore takes into account that the vehicle can be safely braked by a braking system of the vehicle.

As previously mentioned, the present method for controlling a compressed air system of a vehicle is performed when it is indicated that a current state of charge of the energy storage device is equal to or below a threshold state of charge. The state of charge threshold may depend on an estimated state of charge required for the vehicle to reach a geographic location where charging of the energy storage device can be performed. Methods for estimating the state of charge required for a vehicle to reach a geographic location where the energy storage device can be charged are already known in the art and are therefore not described in detail in the present disclosure. Typically, such methods take into account the vehicle's current geographic position and destination, map data (including typographical data), vehicle characteristics (such as vehicle configuration and weight), and so on. Examples of geographic locations where charging of the energy storage device may be performed are a charging station or charging zone where the vehicle may be charged while driving by connecting to a power line over, off, or in the street. Another example of a geographic location where charging of the energy storage device may be performed is a geographic location where regenerative braking of the vehicle may be performed to thereby charge the energy storage device.

Alternatively, the state of charge threshold may be a fixed minimum state of charge threshold of the energy storage device. Such a first minimum state of charge threshold may be preset to ensure that the energy storage device is not at risk of reaching a state of charge where there is an increased risk of degradation of the energy storage device. However, it should be noted that such a fixed minimum state of charge threshold is relevant in most cases only in situations where the energy storage device has a sufficient estimated state of charge required for the vehicle to reach a geographic location where charging of the energy storage device is performed can be. Therefore, performing the method described herein for controlling a compressed air system as a result of an indication that a current state of charge of the energy storage device is equal to or below the fixed minimum state of charge threshold will be significantly less frequent than performing the method as a result of an indication that a current state of charge of the energy storage device is equal to or below a state of charge threshold that depends on an estimated state of charge required for the vehicle to reach a geographic location where charging of the energy storage device can be performed.

The method may further include where the minimum target pressure (P _{_cutin} ) is reduced, a maximum target pressure (P _{_cutoff} ) at which the compressor should temporarily stop compressing air is also reduced to a second predefined target pressure threshold (P _{_cutoff_low} ). As a result, the compressor temporarily stops producing compressed air at a lower pressure than during normal operation where the present method is not applied. This in turn further reduces the energy consumption of the compressor and thus conserves the energy of the energy storage device.

The method may further include determining whether the compressor can be powered by a power supply device other than the energy storage device. If it is determined that the compressor may be powered by a power supply other than the energy storage device, the method may include powering the compressor from said power supply. The other power supply device can be, for example, a regenerative brake of the vehicle. In other words, if the compressor can be powered directly by energy generated by, for example, a regenerative brake of the vehicle, the compressed air system is controlled so that the compressor is powered by the other energy supply device. This can be achieved, for example, by connecting the compressor to an electrical network in the vehicle. Conveniently, when the compressor is powered by a power supply other than the energy storage device, the compressor can be operated to form a buffer in the tank of the compressed air system so that the compressor consumes less energy from the energy storage device when it is no longer being powered by the other power supply can. Therefore, when the compressor is powered by a power supply other than the energy storage device, the method may include operating the compressor at a maximum allowable speed that depends on the configuration of the compressor and/or the compressor power supply available performance. Additionally, when the compressor is powered by a power supply other than the energy storage device, the method may include increasing the maximum target pressure ( _{P_cutoff} ) at which the compressor should temporarily stop compressing air.

Performance of the method described herein for controlling a vehicle's compressed air system may be controlled by programmed instructions. These programmed instructions typically take the form of a computer program which, when executed in or by a controller, causes the controller to effect desired forms of control action. Such instructions can typically be stored on a computer readable medium.

Additionally, the present disclosure provides a controller configured to perform the method described above for controlling a compressed air system of a vehicle. The controller may be configured to perform any of the steps of the method of controlling a compressed air system described herein.

More specifically, the present disclosure provides a controller configured to control a compressed air system of a vehicle. The compressed air system includes an electrically powered compressor configured to be powered by an energy storage device of the vehicle, a tank configured to store compressed air generated by the compressor, and a supply system configured to it supplies pressurized air from the tank to a plurality of air consumers of the vehicle. The controller is configured such that when there is an indication that a current state of charge of the energy storage device is equal to or below a state of charge threshold, it sets a minimum target pressure ( _{P_cutin} ) to be maintained in the tank by the compressor to a first predefined one Target pressure threshold (P _{_cutin_critial} ) reduced if it does not already correspond to the first predefined target pressure threshold (P _{_cutin_critial} ). The controller is further configured to set a desired compressor speed to a speed that is equal to or within a defined interval of the most energy efficient compressor speed as defined by a predetermined compressor efficiency curve, if not already there Corresponds to speed, wherein the efficiency curve represents the specific energy consumption per unit mass of the air compressed by the compressor and is dependent on the first predefined desired pressure threshold value.

The control device for controlling the compressed air system can consist of one or more control units. If the control device comprises a plurality of control units, each control unit can be configured to control a specific function or a specific function can be divided between different control units. The control device can be arranged in the vehicle and thus represent part of the vehicle. The control device can be part of the compressed air system as such. Alternatively, the controller may be separate from the pneumatic system but configured to communicate with the pneumatic system to perform various control actions.

The controller may be further configured to determine whether the current state of charge of the energy storage device is equal to or below the state of charge threshold. To make such a determination, the controller may be configured to estimate the state of charge of the energy storage device required for the vehicle to reach a geographic location where charging of the energy storage device can be performed. Alternatively, the controller may be configured to request and receive information from another controller of the vehicle or a controller remote from the vehicle when an indication has been generated that a current state of charge of the energy storage device is equal to or below the threshold state of charge.

The present disclosure further provides a vehicle including a compressed air system and the controller. The vehicle may be, for example, a heavy-duty land-based vehicle such as a truck, bus, or the like. In addition, the vehicle may be an all-electric vehicle or a hybrid vehicle.

1 schematically shows a side view of an example of a vehicle 1. The vehicle 1 comprises a drive train 2. The vehicle drive train 2 comprises a drive unit in the form of an electric machine 3, which is fed by an energy storage device 5 of the vehicle. The electric machine 3 may be configured to operate as a generator during vehicle regenerative braking, thereby converting the kinetic energy of the vehicle 1 into electrical energy used to charge the energy storage device 5 . The vehicle 1 also includes a transmission 4. The transmission 4 can be connected to the drive wheels 7 of the vehicle 1 via a cardan shaft 6 . The vehicle 1 also includes wheel brakes 9. Typically, each wheel of the vehicle 1 includes a wheel brake 9, so that both the non-driven wheels 8 and the drive wheels 7 include wheel brakes 9.

The vehicle 1 can be a pure electric vehicle. Alternatively, the vehicle 1 can be a hybrid vehicle, in which case the vehicle 1 includes an internal combustion engine (not shown) in addition to the electric machine 3 .

2 shows schematically an example of a compressed air system 10 of a vehicle, such as that in 1 illustrated vehicle 1. In the figure, optional features are represented by dashed lines. Features that are not part of the actual compressed air system 10 are represented by dashed lines. The method for controlling a compressed air system described here can be carried out on the in 2 Compressed air system 10 shown can be carried out.

The compressed air system 10 includes an electrically driven compressor 12 configured to be powered by an energy storage device 5 of the vehicle 1 . The compressed air system 10 further includes a tank 14 configured to store the compressed air generated by the compressor 12 . In addition, the compressed air system 10 includes a supply system 16 that is configured to supply compressed air from the tank 14 to a plurality of air consumers of the vehicle. The multiple air consumers can include, for example, a braking system 21 for braking the vehicle using the service brakes, an air suspension system 22 of the vehicle, a transmission system 23 in which the shifting operations are carried out using pneumatic actuators, and/or an additional system 24 that is connected to the compressed air system 10 to enable the use of compressed air from this system.

The compressed air system 10 may further include an air drying cartridge 18 configured to dry the air compressed by the compressor 12 before the compressed air enters the tank 14 . The air drying cartridge 18 may be configured to be regenerated using pressurized air from the tank 14 . As shown in the figure, the compressed air can be supplied through the supply system 16 . Alternatively, the compressed air required for the regeneration of the air drying cartridge can be supplied from the tank 14 by a separate supply device, if desired.

The compressed air system 10 is controlled by a control device 100 . The controller 100 may be part of the compressed air system 10 as shown in the figure. Alternatively, the controller 100 may be separate from the compressed air system 10 but configured to communicate therewith for control of the compressed air system 10 . The control device 100 can be arranged in the vehicle. Alternatively, parts of the control device can be arranged remotely from the vehicle, for example in a remote control center or the like. The controller 100 may be configured to perform the compressed air system control method described herein.

3 FIG. 12 is a flowchart that schematically illustrates an exemplary embodiment of the method for controlling a compressed air system according to the present disclosure. Optional steps of the method are indicated by dashed lines. The compressed air system can be, for example, the in 2 Act compressed air system 10 shown.

The method may include a first step of determining (S101) whether there is an indication that the current state of charge of the energy storage device is at or below a threshold state of charge. If there is no indication that the current state of charge of the energy storage device is equal to or less than the state of charge threshold, the method returns to the start.

The method includes a step of, when there is an indication that a current state of charge of the energy storage device is at or below a state of charge threshold, setting a minimum target pressure ( _{P_cutin} ) to be maintained in the tank by the compressor to a first predefined one Target pressure threshold value ( _{P_cutin_critial} ) is reduced S102 if this does not already correspond to the first predefined target pressure threshold value ( _{P_cutin_critial} ). The method further comprises a step of setting a target compressor speed to a speed equal to or within a defined interval of the most energy efficient compressor speed defined by a predetermined compressor efficiency curve (unless by chance the target speed is already equal to the most energy efficient speed for the first predefined target pressure threshold (P _{_cutin_critial} )). This efficiency characteristic represents the specific power consumption per unit mass of the air compressed by the compressor and is dependent on the first predefined target pressure threshold value. In this way, the compressor for the first predefined target pressure threshold are operated in the most energy-efficient way.

The method can further include a step of reducing S104 a permissible air consumption from the tank by at least a first air consumer from the plurality of air consumers. The first air consumer is an air consumer other than a braking system configured to brake the vehicle.

The method may further include a step of determining S105 whether the compressor can be powered by a power supply device other than the energy storage device. If it is determined in step S105 that the compressor can be powered by the power supply device, the method may include operating S106 the compressor by the power supply device. In this case, the compressor can expediently be operated at a maximum permissible speed, which depends on the configuration of the compressor and/or the power available to the compressor from the power supply device, in order to generate a compressed air buffer in the tank.

The method can be terminated when a charging process has been initiated in which the energy storage device is being charged, e.g. B. at a charging station or charging zone, or when the energy storage device has reached a preselected state of charge value. Alternatively, the method can be terminated if it is foreseeable that the state of charge of the energy storage device is sufficient for the vehicle to reach a geographical position at which the energy storage device can be charged even if the compressed air system is operated as intended (i.e. not according to the present method).

4 shows schematically an example of a predetermined efficiency characteristic of a compressor of a compressed air system of a vehicle. The efficiency curve represents the specific power consumption per unit mass of the air compressed by the compressor as a function of the speed of the compressor and the target pressure. In 4 three different minimum target pressures P1, P2 and P3 (ie minimum pressures that the compressor must maintain in the tank) are shown, each represented by a curve in the figure. P1 represents a minimum target pressure that is lower than the minimum target pressure P2, which in turn is lower than the minimum target pressure P3. As can be seen from the figure, the most energy-efficient speed of the compressor can be achieved at different speeds v ₁ , v ₂ , v ₃ , depending on the selected minimum target pressure. With a minimum setpoint pressure of P1, the most energy efficient speed of the compressor is v ₁ . At a minimum setpoint pressure of P2, the most energy efficient compressor speed is v ₂ . Thus, assuming that P2 represents the minimum set point pressure used during normal operation of the compressed air system, reducing the minimum set point pressure to P1 according to the method described here also means that the most energy efficient speed of the compressor to maintain the set point pressure of v ₂ is changed to _v1 .

5 12 schematically shows an exemplary embodiment of a device 500. The control device 100 described above can, for example, comprise the device 500, consist of the device 500 or be contained in the device 500.

The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read-write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. B. an operating system, for controlling the function of the device 500 is stored. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a time and date input and transmission unit, an event counter and an interrupt controller (not shown). The non-volatile memory 520 also has a second storage element 540.

A computer program P is provided that includes instructions for controlling a compressed air system of a vehicle, the compressed air system including an electrically driven compressor configured to be powered by an energy storage device of the vehicle, a tank configured to that it stores compressed air generated by the compressor, and a supply system configured to supply compressed air from the tank to a plurality of air consumers of the vehicle. The computer program includes instructions to, when there is an indication that a current state of charge of the energy storage device is equal to or below a state of charge threshold, set a minimum target pressure (P _{_cutin} ) to be maintained in the tank by the compressor to a first predefined target pressure threshold ( P _{_cutin_critial} ) and set a target compressor speed to a speed equal to or within a defined interval of the most energy efficient compressor speed, such as it is defined by a predetermined efficiency characteristic (efficiency characteristic) of the compressor. The efficiency curve represents the specific energy consumption per unit mass of air compressed by the compressor and is dependent on the first predefined desired pressure threshold value ( _{P_cutin_critial} ).

The program P can be stored in an executable form or in compressed form in a memory 560 and/or in a read-write memory 550.

The data processing unit 510 can perform one or more functions, i. H. the data processing unit 510 can execute a specific part of the program P stored in the memory 560 or a specific part of the program P stored in the random access memory 550 .

The data processing unit 510 can communicate with a data port 599 via a data bus 515 . The non-volatile memory 520 is provided for communication with the data processing unit 510 via a data bus 512 . The separate memory 560 is provided for communication with the data processing unit 510 via a data bus 511 . The read/write memory 550 is intended to communicate with the data processing unit 510 via a data bus 514 . The communication between the individual components can take place via a communication link. A communication link can be a physical link such as an optoelectronic communication line or a non-physical link such as a wireless link, e.g. a radio link or a microwave link.

When data is received via the data port 599, it can be temporarily stored in the second storage element 540. When the received input data has been temporarily stored, the data processing unit 510 is ready to execute the code as described above.

Portions of the methods described herein may be performed by device 500 using data processing unit 510 executing the program stored in memory 560 or random access memory 550 . When the device 500 executes the program, the methods described herein are performed.

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• US 8718848 B2 [0003, 0035]
• US10173616 [0004]

Claims (16)

A method of controlling a compressed air system (10) of a vehicle (1) performed by a control device (100), the compressed air system (10) comprising: an electrically driven compressor (12) configured to be powered by an energy storage device (5 ) of the vehicle (1), a tank (14) configured to store compressed air generated by the compressor (12), and a supply system (16) configured to supply compressed air from the tank ( 14) to deliver to a plurality of air consumers (21, 22, 23, 24) of the vehicle (1), the method comprising when there is an indication that a current state of charge of the energy storage device (5) is equal to or below a state of charge threshold : Reducing (S102) a minimum target pressure (P _{_cutin} ) to be maintained in the tank (14) by the compressor (12) to a first predefined target pressure threshold value (P _{_cutin_critial} ), and setting a target speed of the compressor (12). a speed that is equal to or within a defined interval of the most energy efficient speed of the compressor (12) as defined by a predetermined efficiency curve of the compressor (12) if it does not already correspond to that speed, the efficiency curve having a specific energy consumption per unit mass of air compressed by the compressor (12) and is dependent on the first predefined target pressure threshold (P _{_cutin_critial} ). procedure after claim 1 , further comprising: reducing (S104) an allowable air consumption from the tank (14) by at least a first air consumer (22, 23, 24), which is not a brake system (21) configured for braking the vehicle, of the plurality of air consumers. procedure after claim 2 , wherein the first air consumer is selected from the group consisting of an air suspension system (22) of the vehicle, an auxiliary system (24) connected to the compressed air system, a low-entry mode system and a cabin suspension system. Method according to one of the preceding claims, said compressed air system (10) further comprising an air drying cartridge (18) configured to dry air compressed by said compressor (12) before entering said tank (14) and adapted to be exhausted by use of compressed air the tank (14) to be regenerated, and the method further comprising preventing regeneration of the air dryer cartridge (18). Method according to one of the preceding claims, wherein the first predefined target pressure threshold value (P _{_cutin_critial} ) represents a minimum pressure which is to be maintained in the tank (14) in order to ensure that at least a second air consumer (21) of the plurality of air consumers is supplied with sufficient air pressure, so that the second air consumer (21) can be fully operated, the second air consumer (21) being essential for the operational safety of the vehicle (1); or wherein the first predefined target pressure threshold (P _{_cutin_critial} ) represents a required minimum pressure defined by legal requirements and/or by manufacturer recommendations. procedure after claim 5 , wherein the second air consumer is a braking system (21) configured for braking the vehicle. Method according to one of the preceding claims, wherein the state of charge threshold value depends on an estimated state of charge that the vehicle (1) needs to reach a geographical position at which the charging of the energy storage device (5) can be carried out, or wherein the state of charge threshold value is a fixed one Minimum state of charge threshold of the energy storage device (5). Method according to one of the preceding claims, further comprising that when the minimum target pressure (P _{_cutin} ) is reduced, a maximum target pressure (P _{_cutoff} ) at which the compressor (12) should temporarily stop air compression is reduced to a second predefined target pressure threshold value (P _{_cutoff_low} ) is reduced. A method according to any one of the preceding claims, further comprising when it is determined that the compressor (12) can be powered by a power supply other than the energy storage device (5), powering the compressor by that power supply. procedure after claim 9 , wherein the power supply means is a regenerative brake of the vehicle (1). Procedure according to one of claims 9 or 10 , wherein the compressor (12) is operated at a maximum permissible speed of the configuration of the compressor (12) and / or the depends on the power available to the compressor (12) when powered by the power supply. Computer program (P) with instructions which, when executed by a control device (100), cause the control device (100) to carry out the method according to one of the preceding claims. Computer-readable medium with instructions which, when executed by a control device (100), cause the control device (100) to carry out the method according to one of Claims 1 until 11 to execute. A control device (100) configured to control a compressed air system (10) of a vehicle (1), the compressed air system (10) comprising: an electrically driven compressor (12) configured to be powered by an energy storage device (5) of the vehicle (1) to be powered, a tank (14) configured to store compressed air generated by the compressor (12), and a supply system (16) configured to supply compressed air from the tank to a plurality of Air consumers (21, 22, 23, 24) of the vehicle (1), wherein the control device (100) is configured to, when there is an indication that a current state of charge of the energy storage device (5) is equal to or below a state of charge threshold: Reducing (S102) a minimum target pressure (P _{_cutin} ) to be maintained in the tank (14) by the compressor (12) to a first predefined target pressure threshold (P _{_cutin_critial} ), and setting a target speed of the compressor (12) to one Speed that is equal to or within a defined interval around the most energy-efficient speed of the compressor (12) as defined by a predetermined efficiency curve of the compressor (12) if it does not already correspond to this speed, the efficiency curve having a specific energy consumption per Unit of mass of the air compressed by the compressor (12) and is dependent on the first predefined target pressure threshold (P _{_cutin_critial} ). Control device (100) after Claim 14 which is further configured to reduce an allowable air consumption by at least a first air consumer (22, 23, 24), other than a braking system (21) configured to brake the vehicle, of the plurality of air consumers. Vehicle (1) with a compressed air system (10) and the control device (100) according to one of Claims 14 or 15 .

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