Method and arrangement for removing moisture in an air compressor of a vehicle

Abstract

The present disclosure relates to technologies related to vehicles. According to a first aspect, the disclosure relates to a method for removing moisture in an air compressor of a vehicle, wherein the air compressor uses oil for lubrication and / or cooling. The method includes monitoring S1 the air compressor while it delivers compressed air to an air distribution system via an air processing system (APS), wherein starting and stopping of the air compressor is controlled based on a cut-in and cut-out pressure in a connected air distribution system.The method further comprises activating a regeneration S7 of the APS when the air compressor is stopped before an indicator for an operating temperature of the air compressor meets an evaporation criterion S5. The regeneration includes recirculating a portion of the treated air from the air distribution system and through the APS, where it is discharged, thereby reducing the system pressure level below the cut-in pressure and restarting the air compressor. The disclosure further relates to a corresponding control arrangement and a computer program, as well as a vehicle comprising the control arrangement.

Description

Technical area

[0001] The present disclosure relates to technologies related to vehicles. In particular, the disclosure relates to methods for removing moisture from air compressors arranged in vehicles. The disclosure further relates to a corresponding control arrangement and a computer program, as well as to a vehicle comprising the control arrangement. background

[0002] Air compressors are essential components of most vehicles and play a pivotal role in powering essential systems such as air brakes, air suspension, air preparation, and auxiliary power units. Many air compressors use oil for lubrication and cooling. In some of these compressors, the oil is mixed with the compressed air. This can lead to the common problem of moisture ingress into the air compressor oil, resulting from ambient humidity, condensation, or leaks in the system. One cause of moisture in the oil is condensation inside the air compressor due to a rapid drop in temperature, which causes water to form and mix with the oil in the air compressor.

[0003] The presence of moisture decreases lubrication efficiency, increases component wear, and causes acids and residues to form in the oil. Therefore, there is a need to address the problem of water accumulation in the oil of air compressor types that mix compressed air with the air compressor's lubricating oil. Brief outline

[0004] It is an object of the present disclosure to provide a simple and robust way to avoid the problem of moisture in the air compressor oil. In particular, it is an object to provide a solution that does not require additional hardware in the air compressor or the air treatment system. These and other objects are at least partially achieved by the method, control arrangement, and vehicle according to the independent claims and by the embodiments according to the dependent claims.

[0005] According to a first aspect, the disclosure relates to a method for removing moisture in an air compressor of a vehicle, wherein the air compressor uses oil for lubrication and / or cooling. The method includes monitoring the air compressor while it delivers compressed air to an air distribution system via an air processing system (APS), wherein starting and stopping of the air compressor is controlled based on a cut-in and cut-out pressure in a connected air distribution system.The method further comprises activating a regeneration of the APS when the air compressor is stopped before an indicator of an operating temperature of the air compressor meets an evaporation criterion. The regeneration involves recirculating a portion of the treated air from the air distribution system and through the APS, where it is discharged, thereby reducing the system pressure level below the cut-in pressure and restarting the air compressor. The proposed method can ensure that the temperature in the air compressor is high enough after each run so that any moisture that has built up in the air compressor is evaporated. Furthermore, the method is robust and can be used in existing vehicles without the need for additional hardware. The regeneration also has the additional effect of regenerating the APS, and in particular an air drying device of the APS.Scheduled APS regeneration may therefore be omitted or carried out at a later date.

[0006] According to some embodiments, regeneration is activated regardless of whether a regeneration criterion indicating a need for regeneration of the air drying device is met. Therefore, APS regeneration is triggered even if there is no need for APS regeneration.

[0007] According to some embodiments, the method includes checking whether the indicator meets the evaporation criterion each time the air compressor is stopped and activating regeneration accordingly. The method can therefore be executed continuously, making it robust.

[0008] According to some embodiments, monitoring includes monitoring internal and / or external operating conditions of the air compressor, wherein the evaporation criterion is based on the monitored internal and / or external operating conditions. Therefore, the evaporation criterion may consider various factors that affect moisture ingress, allowing it to be more efficient yet reliable.

[0009] According to some embodiments, the indicator comprises a duty cycle of the air compressor, wherein the evaporation criterion includes the duty cycle being above a minimum duty cycle, the duty cycle being measured over a period beginning when the evaporation criterion was last met. The method can thus be applied without requiring temperature sensors in the air compressor.

[0010] According to some embodiments, the indicator comprises a measured or estimated operating temperature, wherein the temperature criterion comprises the operating temperature being above an evaporation temperature for a predetermined period of time. According to some embodiments, the method comprises measuring the operating temperature with one or more sensors disposed in the air compressor. According to some embodiments, the method comprises estimating the operating temperature based on a usage history of the air compressor. Thus, either measurements or estimates may be used.

[0011] According to a second aspect, the disclosure relates to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the first aspect.

[0012] According to a third aspect, the disclosure relates to a computer-readable medium having instructions which, when executed by a computer, cause the computer to perform the method according to the first aspect.

[0013] According to a fourth aspect, the disclosure relates to a control arrangement configured to carry out the method according to one of the embodiments according to the first aspect.

[0014] According to a fifth aspect, the disclosure relates to a vehicle having an air compressor configured to supply compressed air, an APS arranged to condition the compressed air, an air distribution system configured to store and distribute the treated compressed air, wherein starting and stopping of the air compressor is controlled based on a cut-in and cut-out pressure in a connected air distribution system, and having the control arrangement according to the fourth aspect. Short description of the drawings Fig. 1 shows a vehicle in which the proposed method can be carried out. Fig. Figure 2 shows an air compressor and an associated air processing system (APS) of the vehicle in detail. Fig. Figure 3 shows air flows between an air compressor, an APS and an air tank. Fig. Figure 4a shows normal activation of the air compressor and APS regeneration. Fig. Figure 4b shows additional activation of the air compressor and APS regeneration to remove moisture. Fig. 5 is a flowchart of an exemplary method according to the first aspect. Fig. Figure 6 shows how the dew point varies depending on air pressure. Fig. 7a-b show how a working cycle of the air compressor is evaluated. Fig. 8 shows a control arrangement according to the fourth aspect. Detailed description

[0015] The proposed method is based on the realization that the problem of moisture in an air compressor typically occurs in scenarios with a low air compressor duty cycle (i.e., low air consumption) and poor heat storage capacity within the air compressor. The moisture problem arises when the operating temperature in the compressor is too low for water to evaporate. The problem can be solved by maintaining the temperature in the air compressor sufficiently high, which causes the resulting moisture to evaporate.

[0016] To solve the problem, it is proposed herein that a check be carried out to determine whether the temperature needs to be increased when the air compressor stops pumping because full system pressure is present. In other words, a check is carried out to determine whether the operating temperature of the air compressor has reached (or is expected to reach) a certain temperature at which the water contained in the oil evaporates into vapor that can be removed through the air treatment system. The check can be carried out by measuring the temperature inside the air compressor or, alternatively, by analyzing the usage history of the air compressor, since the temperature of the compressor rises when it is pumping, i.e. running. If a certain temperature is not expected to be reached, the system pressure of a connected air distribution system is reduced until a system pressure level is reached at which the air compressor starts pumping again.The inventors have recognized that this is possible with the help of a regeneration valve in an associated air processing system (APS). The regeneration valve is a valve typically used to regenerate an air drying device of an associated air processing system. By using the regeneration valve, the pressure can be reduced using existing hardware. This process is repeated until the specific temperature is expected to be reached. If the vehicle is used in a warm and humid environment, the risk of moisture buildup is generally high. To prevent the buildup of moisture, the process can be designed to run continuously in the background and monitor, for example, the vehicle's air consumption and / or the internal and external conditions of the air compressor.

[0017] The proposed method will now be described with reference to Fig. 1 to 8 explained. Fig. Figure 1 shows a vehicle 1, here a tractor (or a truck). Vehicle 1 may alternatively be a car, a bus, or another type of vehicle. Vehicle 1 comprises a plurality of electrical systems and subsystems. For the sake of simplicity, Fig. 1 only some parts of vehicle 1 are shown that are related to the proposed method. Fig. 1 comprises an air compressor 11, an air processing system (APS) 12 connected to the air compressor 11, an air distribution system 13, various sensors 14 (only one shown), and a control arrangement 10.

[0018] Fig. Figure 2 is a detailed schematic diagram of the air compressor 11 and the connected APS 12. The air compressor 11 is arranged to generate compressed air used by other vehicle systems such as brakes, suspension, drive system (e.g., gearshift), and vehicle body equipment such as doors in a bus, etc. The air compressor 11 may include a piston 43 (as shown) or a rotating element that compresses the incoming air in a compression chamber 41. As the piston 43 moves or the element rotates, the volume of the air decreases, resulting in an increase in pressure. The air compressor 11 is driven, for example, by an electric motor or an internal combustion engine of the vehicle 1. The operation of the air compressor 11 is controlled based on a system pressure level in the air distribution system 13, e.g., a pressure in the air receiver 31 ( Fig. 3). More specifically, the air compressor 11 is controlled based on a cut-in and cut-out pressure in an air distribution system 13. For example, a cut-out pressure is a pressure level at which the air compressor 11 is automatically forced to stop. A cut-in pressure is a pressure level at which the air compressor is automatically started or activated because compressed air is consumed. Automatic starting or stopping of the compressor herein means that there is a direct relationship between pressure and starting / stopping. For example, starting and stopping is controlled based on a sensor signal from a pressure sensor in a system that receives air from the compressor. The air compressor may further include one or more sensors 42, for example, to measure a temperature within (or near) the compression chamber 41.

[0019] The APS 12 is configured to process compressed air. More specifically, the APS 12 is configured to receive compressed air generated by the air compressor 11. APS herein refers to the system that processes the compressed air, e.g., dries or heats it. The APS 12 typically includes an air dryer 21 for drying and filtering the air of particles, such as engine oil. In the example shown, the air dryer 21 includes an air drying device 21a (e.g., a desiccant cartridge or other device that collects water when drying compressed air) and a support element 21b. According to one variant, the support element 21b is referred to as an air dryer body. The support element 21b is connected to a regeneration valve 21c configured to discharge the moisture collected by the filter of the air dryer 21.

[0020] The air dryer 21, in particular the air drying device 21a (or an equivalent absorbent component), must be regenerated when a certain amount of air has flowed through the air drying device 21a. The regeneration valve 21c is used during regeneration, when conditioned air is recirculated through the air drying device 21a of the air dryer 21 for drying, with the air being exhausted through the regeneration valve 21c. This is referred to herein as APS regeneration because the conditioned air regenerates the air dryer 21, e.g., dries and cleans it. According to some embodiments, the regeneration valve 21c is a vent valve. A vent valve can be considered a valve configured to suddenly open a pressurized area to the atmosphere and therefore expel water and particles through an exhaust vent (not shown) of the air drying device.Regeneration can also be performed without this type of explosive release. For example, regeneration can be performed with a regeneration flow that transports water from the air drying device through the exhaust air opening. Therefore, the regeneration valve 21c can also be any valve suitable for controlling such an air flow. In other words, according to some embodiments, the APS 12 includes a regeneration valve 21c arranged to exhaust air.

[0021] The APS 12 is connected to an air distribution system 13. The air distribution system 13 is sometimes considered part of the APS. However, the air distribution system is defined herein as a separate part. The compressed and conditioned air is fed into the air reservoirs 31 via the air distribution system 13. The air distribution system 13 also supplies air to various components 32 of the vehicle 1, e.g., the brakes, the air suspension system, the drivetrain, etc. ( Fig. 3).

[0022] A control arrangement 10 is arranged to control the operation of the compressor 11, the APS 12, and the air distribution system 13. For example, the control arrangement is configured to switch on the compressor 11 or to activate the APS regeneration. The control arrangement is in Fig. 8 described in more detail.

[0023] Fig. Figure 3 shows air flows between an air compressor, an APS 12, and an air receiver. When the air compressor 11 pumps, it delivers compressed air. The compressed air is treated in the APS 12, e.g., dried and filtered, before being delivered to an air distribution system 13 with air receivers 31. This air flow is represented by black arrows.

[0024] The APS 12 can also be operated in a regeneration mode, also called APS regeneration (see Fig. 3). In this mode, the air compressor is stopped, i.e., it is not pumping, and the regeneration valve 21c is open. The treated air is then recirculated through the air drying device 21a of the air dryer 21 and through the regeneration valve 21c ( Fig. 2), regenerating the APS 12. This air flow is represented by white arrows.

[0025] Fig. 4a and Fig. 4b illustrates various scenarios for activation of the air compressor 11 and APS regeneration. The upper curve represents the activation (high) and deactivation (low) of the air compressor, while the lower (dashed) curve represents the activation of regeneration, i.e., the activation (high) and deactivation (low) of the regeneration mode. Fig. Figure 4a illustrates more specifically the standard operation, where regeneration is triggered due to the need to regenerate, dry or clean the APS, while Fig. Figure 4b illustrates the proposed regeneration triggered due to too low a temperature in the air compressor.

[0026] Illustrated in detail Fig. 4a, activation of the air compressor 11 and the APS regeneration when a regeneration criterion is met, ie, when the APS needs to be regenerated. The air compressor initially operates for a time tact1 until it is stopped because the cut-out pressure is reached, ie a sufficient amount of compressed air is present in the air distribution system 13 ( Fig. 3). APS regeneration is triggered when a regeneration criterion is met (represented by the arrow), i.e., when APS regeneration is required. This trigger can occur regularly and / or based on the APS usage history. In response to the trigger, APS regeneration is activated for a short period of time (the lower curve increases). APS regeneration involves opening the regeneration valve 21c ( Fig. 2) and opening an air flow from the air distribution system 13 back to the APS 12. During APS regeneration, the system pressure in the air distribution system 13 drops as air is released from the air tanks 31, causing the air compressor 11 to run for a short period of time t act2is reactivated. The air compressor then remains off until the system pressure in the APS next falls below the cut-in pressure level, ie, when the compressed air is used up and more compressed air is required.

[0027] Fig. Figure 4b shows an activation of the air compressor and the APS regeneration, which is carried out for the purpose of removing moisture from the air compressor according to the proposed method. Thus, the regeneration does not primarily serve to regenerate the APS 12, but rather to increase the operating temperature of the air compressor 11, since the operation of the air compressor inherently leads to an increase in the operating temperature. The air compressor therefore initially operates for a time t act1until the cut-out pressure is reached. In response to the stopping of the air compressor 11, an evaporation criterion is evaluated, which indicates whether the operating temperature of the air compressor is high enough to prevent moisture in the air compressor 11. In this example, the evaluation indicates that the operating temperature is too low, which means that there is a risk of moisture forming in the oil of the air compressor. To increase the operating temperature of the air compressor 11, the APS regeneration is activated (the lower curve rises). During the APS regeneration, the system pressure drops, causing the air compressor 11 to run for a second time t act2is started. If the air compressor 11 is started, regeneration must generally be stopped even if the evaporation criterion is not met, since the air drying device 21a is required to dry the air. If the system pressure level reaches the cut-out pressure, the air compressor switches off again. The evaporation criterion is then evaluated again. If the evaporation still indicates that the operating temperature is too low, the APS regeneration is stopped for a third time t act3 triggered, and so on. APS regeneration can therefore be triggered multiple times (four times in the example shown) until the evaporation criterion indicates that the operating temperature is high enough. Note that in this example, APS regeneration is not triggered because regeneration is required (i.e., no arrow), but rather, APS regeneration is triggered based solely on the evaporation criterion. Fig. Figure 5 is a flow diagram of the proposed method for removing moisture in an air compressor 11 of a vehicle 1, wherein the air compressor 11 uses oil for lubrication and / or cooling. The method can be implemented as a computer program with instructions which, when the program is executed by a computer (e.g., a processor in the control arrangement 10 ( Fig. 8)) is executed, cause the computer to execute the method. According to some embodiments, the computer program is stored in a computer-readable medium (e.g., memory or compact disc) with instructions that, when executed by a

[0028] Computer, causing the computer to execute the method. According to some embodiments, the method is carried out in a control arrangement 10 of a vehicle 1, e.g. in the vehicle of Fig. 1. The method can be executed at any time during normal driving. The proposed method is now described with reference to the flowchart in Fig. 5 and the other figures.

[0029] During operation of the vehicle 1, the air compressor is operated to supply various systems of the vehicle 1 with compressed air, as described above. The method is therefore carried out while the air compressor is arranged to supply compressed air to an air distribution system 13 via an APS 12, which dries the air. Sometimes the air compressor is switched on automatically when an engine or other component of the vehicle is started. Alternatively, the air compressor is switched on by a separate signal or switch. In other words, the air compressor is switched on, i.e., it is supplied with power. When the compressor is switched on, it is considered to be in operation, even if it is not pumping / running. During normal operation, starting and stopping of the air compressor 11 is controlled based on a switch-on and switch-off pressure in a connected air distribution system 13. This means that the air compressor is active and running (i.e.,The air compressor 11 begins (i.e., pumping) when compressed air is needed and stops when the air tanks are full. As described above, the compressed air is conditioned by the APS 12 before being stored and / or distributed. In other words, according to some embodiments, the method includes operating S0 the air compressor 11 to deliver compressed air to an air distribution system 13 via an air processing system (APS) that dries the air.

[0030] The proposed method includes monitoring the operation of the air compressor 11 during normal air compressor operation. In other words, the method includes monitoring S1 the air compressor 11 while it delivers compressed air to an air distribution system 13 via an air processing system (APS) that dries the air. This includes monitoring the starts and stops of the air compressor. Starts and stops can be monitored using electrical signals. According to some embodiments, the sensors 42, 14 ( Fig. 1 and Fig. 2) arranged to monitor the vehicle's air consumption as well as the internal and external conditions of the air compressor. Sensors 42 may, for example, record internal conditions such as a temperature in the air compressor chamber 41. Other sensors 14 may be arranged to measure external conditions such as humidity, temperature, and air pressure. In other words, according to some embodiments, monitoring S1 comprises monitoring internal and / or external conditions of the air compressor 11. If there is a low risk of moisture, monitoring S1 may sometimes run in the background. Alternatively, the method may be disabled in scenarios where it is deemed unnecessary or resource-intensive.

[0031] The operation of the air compressor is controlled based on a system pressure in the air distribution system 13, which is used to distribute the compressed and conditioned air. The air compressor 11 is typically controlled to start when a system pressure in the air distribution system 13 falls below a cut-in pressure. For example, a start signal is sent to the air compressor 11. The start signal comes, for example, from a pressure sensor arranged in the APS 12 or in the air distribution system 13. In other words, according to some embodiments, the method comprises starting S2 the air compressor 11 when the system pressure level falls below a cut-in pressure. While the air compressor is running, the system pressure increases. When the system pressure equals or meets a cut-out pressure, the air compressor is turned off or stopped S3.This prevents the system pressure from becoming too high, which could cause damage to the APS 12 or the air distribution system 13. For example, a stop signal is sent to the air compressor 11. The stop signal comes, for example, from a pressure sensor arranged in the APS 12 or the air distribution system 13. In other words, according to some embodiments, the method comprises stopping S3 the air compressor 11 when the system pressure level reaches (or corresponds to) a cut-out pressure. The "normal" starting and stopping of the air compressor 11, which is triggered when compressed air is needed, is thus based on a cut-in and cut-out pressure in a connected air distribution system 13.The control of this normal starting and stopping, which is initiated by the on / off pressure, is usually built into or preconfigured in the APS 12 and / or the air distribution system 13 and is therefore not controlled by the control arrangement 10 but monitored by the control arrangement 10.

[0032] The proposed idea is based on the realization that problems associated with moisture in the air compressor can be avoided if the temperature of the air compressor, referred to herein as the operating temperature, is kept sufficiently high. The operating temperature can be defined, for example, as a temperature inside the compression chamber 41 or at another relevant location in or on the air compressor 11. The required operating temperature is a temperature at which evaporation corresponds to a certain rate, i.e., water should evaporate sufficiently quickly. The required operating temperature depends on the dew point. The dew point is the temperature at which a certain volume of air at a certain atmospheric pressure is saturated with water vapor, leading to condensation and dew formation. It is therefore the temperature below which the air can no longer contain water in a gaseous state.The dew point varies depending on the vehicle's environmental conditions, such as air pressure, temperature, and humidity. Fig. Figure 6 illustrates the dew point (x-axis) versus air pressure (y-axis) at a relative humidity of 95% at three different ambient temperatures (20, 30, and 40° Celsius). Therefore, the required operating temperature can be dynamically estimated based on environmental parameters such as air pressure, temperature, and humidity. Alternatively, a fixed required operating temperature can be defined.

[0033] Therefore, when stopping S3 the air compressor, the operating temperature must be evaluated to avoid stopping the air compressor at too low a temperature. In other words, according to some embodiments, the method comprises obtaining S4 an indicator of the operating temperature of the air compressor 11. Obtaining S4 may occur when the compressor stops pumping, e.g., when the system pressure corresponds to the cut-out pressure. The indicator may be a temperature obtained S4 with a sensor 42 arranged in the air compressor 11, for example, in the air compressor chamber 41. In other words, according to some embodiments, obtaining S4 comprises measuring S4a the operating temperature with one or more sensors 42 arranged in the air compressor 11.

[0034] However, if no sensor is available, other information indicating the operating temperature may be used. Therefore, some embodiments are based on the finding that the temperature in the air compressor chamber 41 depends primarily on the usage history of the air compressor, e.g., on a duty cycle of the air compressor. Therefore, according to some embodiments, the length of the last duty cycle may be used as an indicator of the temperature.

[0035] For example, the duty cycle (i.e., the proportion of time the air compressor is running compared to the total time of the cycle) can be estimated during a cycle that begins when the temperature was last high enough for moisture to evaporate. For example, the vehicle's air consumption, as well as the internal and external conditions of the air compressor, can be continuously monitored while driving. When the air compressor starts pumping due to air consumption (i.e., the cut-in pressure is reached), this information can be received from sensors 14, 42, for example, via CAN ( Fig. 8) and used to assess whether and by how much the air compressor's duty cycle needs to be increased to reach a desired temperature at which the moisture evaporates. If the air compressor 11 stops pumping because the system pressure equals the cut-out pressure, the actual duty cycle can be compared with the duty cycle required for the moisture to evaporate.

[0036] According to another embodiment, the length of the last operating cycle is used to estimate the current temperature. In other words, according to some embodiments, the method comprises estimating S4b the operating temperature based on a usage history of the air compressor. According to some embodiments, estimating S4b comprises estimating the temperature based on a operating cycle of the air compressor 11 during a period beginning when the estimated operating temperature last met the evaporation criterion. This may typically be at a time when the previous activation of the air compressor ended. The indicator of the operating temperature may therefore be a measured temperature, a operating cycle, or another quantity.According to some embodiments, the indicator is estimated based on extended estimates using additional parameters that may affect the air compressor temperature, such as outside temperature, humidity, etc.

[0037] The obtained indicator is then evaluated against an evaporation criterion. The evaporation criterion is a formula or rule that can be used to determine whether the operating temperature of the air compressor 11 is expected to be high enough to evaporate the moisture formed in the air compressor 11. The exact values ​​of the evaporation criterion depend on the implementation and can be determined based on dew point, experiments, desired safety margins, usage history, etc. If the indicator indicates that the operating temperature does not meet an evaporation criterion when the air compressor 11 is automatically switched off, the system pressure should be reduced so that the air compressor starts up again. In other words, the method includes checking whether the indicator for the operating temperature of the air compressor 11 meets an evaporation criterion S5.

[0038] If the indicator is a duty cycle, the evaporation criterion may define a required minimum duty cycle. In other words, according to some embodiments, the indicator comprises a duty cycle of the air compressor 11, wherein the evaporation criterion includes the duty cycle being above a minimum duty cycle, the duty cycle being measured over a period beginning when the evaporation criterion was last met. For example, a duty cycle of at least 20% may be required for the evaporation criterion to be met.

[0039] Fig. Figures 7a-b show how an air compressor duty cycle can be evaluated. The diagrams illustrate compressor activation, where "low" means the compressor is not running, and "high" means the compressor is running. Fig. 7a, the working cycle is performed during a time t totalestimated starting when the evaporation criterion was last met.

[0040] In Fig. 7a the compressor was switched on during the total time t total only once with an active time t act activated. The working cycle then corresponds tactttotal, which is less than 20%. The proposed process thus triggers APS regeneration. Fig. 7b, APS regeneration was activated three times, so the processor runs three more times. The duty cycle is called ∑tactttotal is calculated, which means the evaporation criterion is now met. Therefore, no further APS regeneration is triggered. The number of required activations depends on the time elapsed since the last activation of compressor 11.

[0041] If the indicator is a temperature, the evaporation criterion can define a required minimum measured temperature. In other words, according to some embodiments, the indicator comprises a measured or estimated operating temperature, wherein the temperature criterion includes the operating temperature being above an evaporation temperature for a predetermined period of time. For example, a measured temperature of at least 20°C above the dew point is required for the evaporation criterion to be met.

[0042] If the evaporation criterion is met, no additional regeneration is required to increase the temperature. However, regeneration may be necessary at certain intervals to maintain the efficiency and effectiveness of the drying system. In other words, according to some embodiments, the method comprises an APS regeneration S7 if the regeneration criterion is met S6. Thus, an APS regeneration occurs from time to time even in weather conditions with a low risk of condensation. Regeneration refers herein to a process in which air-conditioning components of the APS, e.g., the air drying device 21a, are regenerated (e.g., dried and cleaned). Regeneration is herein a process that results in the release of air from the system. Regeneration can occur by purging the air drying device 21a or by means of a controlled air flow through the air drying device 21a.

[0043] However, if reactivation of the air compressor is required to increase the operating temperature, i.e., if the evaporation criterion is not met, the regeneration valve 21c is opened to release compressed air until the system pressure reaches a system pressure level at which the air compressor starts pumping again. In other words, regeneration of the air drying device 21a serves to reduce the system pressure, causing the compressor 11 to restart. In other words, the method includes regeneration S7 of the APS 12 upon stopping S3 of the air compressor 11 if the system pressure level meets a cut-out pressure before an indicator of an operating temperature of the air compressor 11 meets or corresponds to an evaporation criterion S5.More specifically, regeneration S7 involves recirculating a portion of the treated air through the air drying device 21 and out of the APS, causing the system pressure level to drop below the cut-in pressure and the air compressor to restart S2. Regeneration S7 may involve controlling one or more valves or switches in the APS 12 and / or in the air distribution system 13, e.g., the regeneration valve 21c. Regeneration S7 typically occurs in the same way as APS regeneration when regeneration is required. Therefore, regeneration corresponds to a function already implemented in most APSs currently on the market. However, APS regeneration is activated even when there is no need for regeneration. In other words, regeneration S7 occurs regardless of whether a regeneration criterion S6 is met, indicating a need for regeneration of the air drying device 21.

[0044] Regeneration S7 is repeated as long as the duty cycle is below a target duty cycle to ensure that the air compressor reaches the operating temperature that contributes to evaporating the water contained in the oil and conveying it into the air treatment system. In other words, according to some embodiments, the method includes checking S5 whether the indicator meets the evaporation criterion and activating regeneration S7 accordingly each time the air compressor 11 stops operating.

[0045] The embodiments described so far relate to a vehicle 1 with a single air dryer. According to some embodiments, a vehicle may have multiple air dryers. With a dual air dryer, it is possible to regenerate the APS 12 and operate the air compressor 11 at the same time, so the solution could look somewhat different. The basic concept would be the same with dual air dryers, i.e., the evaporation criterion can be evaluated and a decision made to activate the compressor. In the above examples with a single air dryer, regeneration must be terminated when the cut-in pressure is reached. However, in a solution with a dual air dryer, regeneration can continue until the evaporation criterion is met. In principle, regeneration could begin as soon as it is determined that the evaporation criterion is not met. In other words, regeneration could already begin at the end of t act1 ( Fig. 4b) and continue until the evaporation criterion, i.e., a measured or estimated temperature, is high enough. An advantage of this solution with a double air dryer is that air can be discharged from the system with a continuous flow, both when the air compressor 11 is stopped and when it is pumping. More precisely, it is only necessary to control which air drying device 21a is currently being used for pumping and which drying device 21a is currently being regenerated. Consequently, the load phases in which the air compressor 11 is active will be longer. However, the number of activations and the total time are reduced.

[0046] Now to Fig. 8., in which the control arrangement 10 is shown, which in the vehicle ( Fig. 1) is arranged and set up to implement the proposed procedure ( Fig. 5) to remove moisture in an air compressor 11 of a vehicle. According to some embodiments, the control arrangement 10 is a "unit" in a functional sense. According to some embodiments, the control arrangement 10 is therefore a control arrangement with multiple physical control arrangements that cooperate with one another.

[0047] The control arrangement 10 comprises one or more electronic control units (ECUs). An ECU is essentially a digital computer that controls one or more electrical systems (or electrical subsystems) of the vehicle 1. ECU is a general term used in automotive electronics for an embedded system that controls one or more functions of the electrical system or subsystems in a transport vehicle. The vehicle 1 typically comprises a plurality of ECUs that communicate via a Controller Area Network (CAN), which could be replaced in the future, for example, by Ethernet-based solutions.

[0048] The control arrangement comprises a processor, a memory 102, and a communication interface. The processor 101 is essentially a computer. In other words, processor 101 refers herein to hardware or hardware / firmware implemented with processing circuitry, in particular a processor, a central processing unit (CPU), a controller, an arithmetic logic unit (ALU), a digital signal processor, a microcomputer, a field-programmable gate array (FPGA), a system-on-chip (SoC), a programmable logic unit, a microprocessor, an application-specific integrated circuit, or any other device capable of electronically executing operations in a defined manner. Memory 102 (or computer-readable medium) refers herein to any non-transitory, computer-readable medium, e.g.,a tangible electronic, magnetic, optical, infrared, electromagnetic and / or semiconductor system, device and / or apparatus.

[0049] The communication interface 103 is, for example, a CAN connector. The communication interface 103 is configured to enable communication with other systems and devices of the vehicle 1. In particular, the communication interface enables the control arrangement to receive sensor data from the sensors 14, 42. The communication interface 103 can also be configured to monitor S1 the operation of the compressor 11, e.g., to detect when the compressor starts and stops. The communication interface 103 is also configured to send a signal to the APS 12 and / or the air distribution system that activates APS regeneration.

[0050] The control arrangement 10 is designed to carry out the process ( Fig.5) to remove moisture in an air compressor 11 of a vehicle, wherein the operation of the air compressor 11 is controlled based on a system pressure level in an associated air processing system (APS) 12. In particular, the control arrangement 10 is configured to monitor the air compressor 11 while it supplies compressed air to an air distribution system 13 via an air processing system (APS) (which processes the air), wherein starting and stopping of the air compressor 11 is controlled based on a cut-in and cut-out pressure in an associated air distribution system 13.The control arrangement 10 is further configured to activate a regeneration of the APS 12 upon stopping the air compressor 11 before an indicator for an operating temperature of the air compressor 11 meets an evaporation criterion. The regeneration includes recirculating a portion of the dried air from the air distribution system and through the air drying device 21 and out of the APS, thereby reducing the system pressure level below the cut-in pressure and restarting the air compressor. According to further embodiments, the control arrangement 10 is configured to implement one of the aspects of the method described above.

[0051] The terminology used in the description of the embodiments illustrated in the accompanying drawings is not intended to limit the method, control arrangement, or computer program as described. Various changes, substitutions, and / or modifications may be made without departing from the disclosed embodiments defined in the appended claims.

[0052] Unless expressly stated otherwise, the term "or" as used herein should be understood as a mathematical OR, i.e., an inclusive disjunction, not a mathematical exclusive OR (XOR). Furthermore, unless expressly stated otherwise, the singular forms "a" and "the" should be understood as "at least one," so that they can also encompass a plurality of similar entities. It is further understood that the terms "comprises," "comprises," "having," and / or "comprising" indicate the presence of the recited features, measures, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, measures, integers, steps, operations, elements, components, and / or groups thereof. A single entity, e.g., a processor, may perform the functions of several items recited in the claims.

Claims

[1] A method for removing moisture in an air compressor (11) of a vehicle, the air compressor (11) using oil for lubrication and / or cooling, the method comprising: - monitoring (S1) the air compressor (11) while it supplies compressed air to an air distribution system (13) via an air processing system (APS), wherein starting and stopping of the air compressor (11) is controlled based on a cut-in and cut-out pressure in a connected air distribution system (13), and when stopping (S3) the air compressor (11) before an indicator for an operating temperature of the air compressor (11) meets an evaporation criterion (S5): - activating a regeneration (S7) of the APS (12), wherein the regeneration includes recirculating a portion of the treated air from the air distribution system (13) and back through the APS where it is discharged, whereby the system pressure level drops below the cut-in pressure and the air compressor is restarted (S2). [2] Method according to one of the preceding claims, wherein the activation of the regeneration (S7) occurs independently of whether a regeneration criterion is met (S6) which indicates a need for regeneration of the air drying device (21). [3] A method according to any one of the preceding claims, comprising: - Check (S5) each time the air compressor (11) stops whether the indicator meets the evaporation criterion and activate the regeneration accordingly (S7). [4] Method according to one of the preceding claims, wherein the monitoring (S1) comprises monitoring internal and / or external operating conditions of the air compressor (11) and wherein the evaporation criterion is based on the monitored internal and / or external operating conditions. [5] A method according to any one of the preceding claims, wherein the indicator comprises a duty cycle of the air compressor (11) and wherein the evaporation criterion comprises the duty cycle being above a minimum duty cycle, the duty cycle being measured over a period starting when the evaporation criterion was last met. [6] A method according to any one of the preceding claims, wherein the indicator comprises a measured or estimated operating temperature and wherein the temperature criterion comprises the operating temperature being above an evaporation temperature for a predetermined period of time. [7] Method according to claim 6, wherein the method comprises measuring (S4a) the operating temperature with one or more sensors arranged in the air compressor (11). [8] A computer program comprising instructions which, when the computer program is executed by a computer, control an air compressor (11) and an APS (12) to carry out the method according to any one of the preceding claims. [9] A computer-readable medium containing instructions which, when executed by a computer, control an air compressor (11) and an APS (12) to carry out the method according to any one of claims 1 to 7. [10] A control arrangement (10) adapted to remove moisture in an air compressor (11) of a vehicle, wherein the operation of the air compressor (11) is controlled based on a system pressure level in an associated air processing system (APS) (12), the control arrangement being adapted to: - monitoring the air compressor (11) while it supplies compressed air to an air distribution system (13) via an air processing system (APS) that dries the air, wherein starting and stopping of the air compressor (11) is controlled based on a cut-in and cut-out pressure in a connected air distribution system (13), and when stopping (S3) the air compressor (11) before an indicator for an operating temperature of the air compressor (11) satisfies an evaporation criterion (S5): - activating a regeneration of the APS (12), wherein the regeneration includes a return of a portion of the treated air from the air distribution system and through the air drying device (21) and from the APS, whereby the system pressure level drops below the cut-in pressure and the air compressor is restarted (S2). [11] Control arrangement (10) according to claim 10, wherein the control arrangement (10) is arranged to carry out the method according to one of claims 2-7. [12] Vehicle (1) comprising: - an air compressor (11) arranged to supply compressed air, - an APS (12) arranged to process the compressed air, - an air distribution system (13) arranged to store and distribute the treated compressed air, wherein starting and stopping of the air compressor (11) is controlled based on a cut-in and cut-out pressure in a connected air distribution system (13), - and the control arrangement (10) according to claim 10 or 11.

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