DE102022112936A1 - Compressed air generating device and method for operating the same - Google Patents

Abstract

The invention relates to a compressed air generating device (2) with a control and regulating device (28), with an electric motor (24) that can be controlled and regulated by the control and regulating device (28), with at least one air compressor (16) that can be driven by the electric motor (24). ; 18), with an air inlet (8), via which ambient air (L) can be sucked into the at least one air compressor, with at least one air cooler (20; 22), which is connected to the outlet of the at least one air compressor, with at least one air dryer (40), which is connected to the outlet of the at least one air cooler, with a coolant inlet opening (12), via which a liquid coolant can be supplied to the at least one air cooler and other components of the compressed air generating device, with a coolant outlet opening (14), via which heated coolant can be removed from the compressed air generating device (2), and with at least one temperature sensor (73, 73', 73"), which is connected to the control and regulating device (28) via a data or sensor line (59). In order to determine the regeneration compressed air volume which must be passed through a drying agent (41) of the air dryer (40) for regeneration, it is provided that the temperature sensor for measuring the coolant temperature is arranged in front of the coolant inlet or behind the coolant outlet of the air cooler (22) which is in Flow direction of the compressed air is arranged as the last air cooler in front of the air dryer. The invention also relates to a method for operating such a compressed air generating device.

Description

The invention relates to a compressed air generating device, with a control and regulating device, with an electric motor that can be controlled and regulated by the control and regulating device, with at least one air compressor that can be driven by the electric motor, with an air inlet via which ambient air can be sucked into the at least one air compressor, with at least one air cooler, which is connected to the output of the at least one air compressor, with at least one air dryer, which is connected to the output of the at least one air cooler, with a coolant inlet opening through which the at least one air cooler and other components of the compressed air generating device receive a liquid coolant can be supplied, with a coolant outlet opening, via which heated coolant can be removed from the compressed air generating device, and with at least one temperature sensor, which is connected to the control and regulating device via a data or sensor line. The invention also relates to a method for operating such a compressed air generating device.

Electrically driven compressors for generating compressed air in vehicles are already known in various embodiments and, for example, in DE 10 2018 139 058 A1 , DE 10 2013 003 513 A1 and EP 3 516 218 B1 described. From the EP 3 331 738 B1 a compressed air generating device for a vehicle with a piston compressor and two compression stages is known. The cylinder spaces of the two compression stages are connected to one another by a connecting line through which the compressed air generated in the first compression stage can be fed to the second compression stage. When the piston compressor is in operation, the ambient air pressure in the first compression stage is increased with the help of a counterpressure that builds up in the subsequent connecting line. An intercooler is arranged in the connecting line between the two compression stages and serves to cool the air heated during compression in the first compression stage. The pressure of the compressed air in the connecting line drops.

The intercooler can therefore increase the efficiency of the second compression stage. Furthermore, further devices for processing the air used can be arranged before or after the first compression stage, such as further cooling devices or air drying devices. One disadvantage is that the compressor described is designed as a reciprocating piston compressor, which disadvantageously requires a lubricant. In addition, the design of the cooling system is not described further.

In addition, from the DE 10 2004 051 435 B3 a system for generating dry compressed air is known, which has a cooled compressor for sucking in and compressing ambient air. The compressor is followed by a cooler in the direction of flow of the compressed air, which serves to cool the compressed air generated. The cooling effect of the cooler is achieved by means of a fan and water droplets directed onto the surface of the cooler, which evaporate there and thereby remove heat from the cooler and indirectly from the compressed air. The cooler is followed by an air dryer which contains a desiccant that removes moisture from the compressed air and thereby lowers the dew point of this compressed air. The compressed air dried in this way has an air humidity of less than 35% at the outlet of the air dryer, which should be sufficient to protect devices subsequently supplied with this compressed air from corrosion or freezing due to the formation of water ice.

Next is from the DE 44 45 972 C2 a compressor system for generating dry compressed air is known, in which an air-cooled radiator is used to cool the compressed air generated by a compressor. There is a water separator downstream of the radiator, by means of which water droplets can be removed from the compressed air, which are formed by condensation when the compressed air cools down. Since the compressed air is not yet sufficiently dry to be able to avoid freezing at low temperatures when used in pressure medium consumers, the water separator is followed by an air dryer in which the compressed air is further dried.

In addition, it is from the unpublished one DE 10 2021 121 424.6 The applicant is aware of a compressed air generating device which has an electric motor which can drive two air compressors arranged in series. During operation of the compressed air generating device, ambient air is sucked in and compressed using the first air compressor. From there, the pre-compressed compressed air is fed to the second air compressor via a check valve, an intercooler and a switching valve. In the second air compressor, the pre-compressed compressed air is further compressed and then passed on to compressed air consumers via an aftercooler or another switching valve. The intercooler and the aftercooler are cooled using a liquid coolant and are used to cool the compressed air generated by the air compressors. The liquid coolant comes, for example, from a vehicle cooling circuit In the compressed air generating device, first supplies a cooling device of the electric motor, then the intercooler and then a cooling device of the first air compressor. From there, the coolant goes to the aftercooler and then to a cooling device of the second air compressor before the coolant is returned to the vehicle's cooling circuit. An air dryer is neither shown nor described in this compressed air generating device.

In addition, from the US 2010/0 303 658 A1 a water-cooled and oil two-stage air compressor is known, which has a water-cooled intercooler which is arranged between a first air compressor and a second air compressor with regard to the air flow. The air compressed by the first air compressor is cooled by the intercooler, and the air compressed by the second air compressor is cooled by an aftercooler whose cooling water inlet is hydraulically connected to the cooling water outlet of the intercooler.

Finally it's out of the DE 11 2015 006 955 T5 a compressed air supply system for locomotives and a method for operating the same are known, in which the air sucked in and compressed by a compressor is cooled in an air cooler and then fed to a first compressed air storage. From this first compressed air reservoir, the compressed air travels via a check valve that closes in the return flow direction to a prefilter which has a drainage valve. After separating liquid and aerosolized water from the compressed air in the pre-filter, the compressed air goes to an air dryer. A temperature sensor arranged at the air flow inlet of the air dryer or in its immediate vicinity is connected to a control unit via a sensor line. The temperature sensor can measure the actual temperature of the compressed air flowing into the air dryer and make this measured value available to the control unit. The controller can calculate an appropriate purge cycle time for the drain valve based on the saturation partial pressure of water vapor at the measured actual temperature of the compressed air and control its operation to remove the water accumulated in the pre-filter.

The desiccant of the air dryer of such generic compressed air generating devices must also be repeatedly freed from the moisture that has accumulated there, because if the moisture absorption capacity of its desiccant is saturated, it is no longer able to work in accordance with the task. In order to remove this moisture from the air dryer, it is known to pass dry compressed air generated by the compressed air generating device and stored in a pressure medium storage back through the air dryer in a so-called regeneration process. Here, the dry compressed air absorbs moisture from the desiccant of the air dryer and transports it outside into the environment of the compressed air generating device. Since these regeneration processes consume dried compressed air, which is actually required in a motor vehicle, for example, for the actuation of, for example, brake actuators and/or air bellows, additional operating times of the compressor are necessary in order to also stock up on sufficient compressed air for the regeneration processes. However, this is associated with additional energy consumption, which increases the operating costs of a motor vehicle, for example, and ultimately also releases environmentally harmful CO ₂ into the atmosphere through the generation of electrical energy for the electric motor.

Against this background, the object of the invention is to present a compressed air generating device with a compressor, a liquid cooling system and an air dryer, the consumption of dried compressed air for the regeneration of a desiccant of the air dryer is reduced in comparison to conventional generic compressed air generating devices. In addition, it should be possible to determine the regeneration compressed air volume that is expected to be required for the respective regeneration of the drying agent. In addition, a method for operating such a compressed air generating device will be presented.

This problem is solved with a compressed air generating device which has the features of claim 1. An independent method claim defines a method for operating such a compressed air generating device. Advantageous refinements and further developments are mentioned in the respectively assigned dependent claims.

Accordingly, the invention initially relates to a compressed air generating device with a control and regulating device, with an electric motor that can be controlled and regulated by the control and regulating device, with at least one air compressor that can be driven by the electric motor, with an air inlet via which ambient air can be sucked into the at least one air compressor , with at least one air cooler, which is connected to the output of the at least one air compressor, with at least one air dryer, which is connected to the output of the at least one air cooler, with a coolant inlet opening, via which the at least one air cooler and other components A liquid coolant can be supplied to the compressed air generating device, with a coolant outlet opening through which heated coolant can be removed from the compressed air generating device, and with at least one temperature sensor, which is connected to the control and regulating device via a data or sensor line.

In order to solve the task relating to the device, this compressed air generating device also provides that the temperature sensor for measuring the coolant temperature is arranged in front of the coolant inlet or behind the coolant outlet of the air cooler, which is arranged as the last air cooler in front of the air dryer in the direction of flow of the compressed air.

The invention is based on the first finding that the compressed air transports a certain amount of water as air humidity after leaving the last air cooler and before reaching the air dryer, depending on its temperature. So if the temperature of the compressed air after leaving the last air cooler before reaching the air dryer is known, it can be calculated how much water the compressed air carries with it as humidity. If the volume flow of compressed air in the previous compressed air generation operation and the absorption capacity of the desiccant in the air dryer are known, it can be calculated how large a regeneration compressed air volume must be in order to dry the desiccant with dry regeneration compressed air during a break in compressed air generation in a regeneration operation.

For indirectly measuring the temperature of the compressed air, it is provided according to the invention that the temperature sensor for measuring the coolant temperature is arranged in front of the coolant inlet opening of the compressed air generating device. This allows the measured values of a temperature sensor to be used, which is located outside the installation space of the compressed air generating device. If the liquid cooling system of such a compressed air generating device also uses a vehicle cooling system with a temperature sensor that is already present on the vehicle, no further temperature sensor has to be arranged for the compressed air generating device in order to save space and costs.

However, if the temperature sensor mentioned is integrated in the installation space of the compressed air generating device, it can be provided that it is arranged directly in front of the coolant inlet of the air cooler, which is arranged as the last air cooler in front of the air dryer in the flow direction of the compressed air.

Alternatively or additionally, it can be provided that the temperature sensor for measuring the coolant temperature is arranged behind the coolant outlet of the air cooler as the next component, which is arranged as the last air cooler in front of the air dryer in the flow direction of the compressed air. By comparing the coolant temperatures before and after this last air cooler, it can be determined how much heat is removed from the compressed air flow at this air cooler. This knowledge can be used to regulate a coolant pump with regard to its pumping performance.

A second finding is that if the compressed air is particularly cold when it enters the air dryer, it carries comparatively little water with it in the form of air humidity. If it is possible to cool the compressed air as much as possible before it reaches the air dryer, then relatively little water will be introduced into the drying agent of the air dryer. As a direct result of this, during a break in the compressed air generation operation during a regeneration operation, comparatively little regeneration compressed air volume is required to dry the desiccant of the air dryer.

To use this knowledge, the invention also provides that the air cooler, which is arranged as the last air cooler in front of the air dryer in the flow direction of the compressed air, is arranged in such a way that it can be flowed through first by the coolant when viewed in the flow direction of the coolant.

The knowledge about the temperature of the compressed air after it leaves the air cooler that is arranged last in the compressed air flow before the air dryer is of great importance. The indirect determination of the temperature of the compressed air at the point mentioned is, as explained above, simpler and more cost-effective than measuring the compressed air temperature in the compressed air flow between the air cooler mentioned and the air dryer.

According to a further specialization of the compressed air generating device, it can have the following: an electric motor, two air compressors that can be driven by the electric motor and act one after the other, an air inlet through which ambient air can be sucked in by means of the first air compressor, two air coolers for cooling the compressed air, which act as an intermediate cooler or as Aftercoolers are designed and arranged, the inlet of the intercooler being pneumatically connected to the outlet of the first air compressor, the outlet of the intercooler being connected to the inlet of the second air compressor is pneumatically connected, the output of the second air compressor being pneumatically connected to the inlet of the aftercooler, and the outlet of the aftercooler being pneumatically connected to the inlet of an air dryer, as well as a coolant inlet opening through which a liquid coolant can be supplied to the intercooler and the aftercooler is, and a coolant outlet opening through which heated coolant can be removed.

In such a compressed air generating device, it is provided according to the invention that the aftercooler is arranged in such a way that, viewed in the flow direction of the coolant, the coolant can flow through it first, and that at least one temperature sensor is present, which is used to measure the temperature of the coolant in the flow direction or is arranged behind the aftercooler.

In this compressed air generating device, the two findings mentioned have been taken into account as design instructions, namely firstly the arrangement of a temperature sensor for measuring the coolant temperature in front of or behind the air cooler, here the aftercooler, which is arranged last in the compressed air flow in front of the air dryer. In addition, in this compressed air generating device it is provided that the liquid coolant first reaches the aftercooler mentioned and, as far as the cooling system permits, cools the compressed air there as much as possible before it reaches the air dryer.

Accordingly, in a departure from the previously known designs, an aftercooler is first flowed through by the still comparatively cold liquid coolant, which is arranged directly in front of the air dryer when viewed in the flow direction of the compressed air. This cools the compressed air as much as possible, so that some of the humidity contained in this compressed air precipitates in the form of small drops of water before it reaches the air dryer. This water is then removed from the compressed air, for example by a water separator in the aftercooler, before it reaches the air dryer. A small amount of condensed water droplets can be carried along by the comparatively strongly cooled compressed air via a short compressed air line to the air dryer, in whose inlet collection area these water droplets collect and are removed during the next regeneration process with the regeneration compressed air flowing out of the air dryer. If there is no water separator, all the water droplets that condense in front of the air dryer are carried along to the collection area on the inlet side of the air dryer. Because this means that a comparatively large amount of moisture has been removed from the compressed air before the air dryer reaches the drying agent, the air dryer is then required less to dry the compressed air. As a result, a regeneration process that consumes dried compressed air needs to be carried out on the air dryer less frequently or a smaller amount of compressed air is required per regeneration process, which protects the supply of stored dry compressed air.

According to a further development of the compressed air generating device described, it is provided that the electric motor, an inverter influencing the operation of the electric motor, the two air compressors, the intercooler, the aftercooler, the air dryer, a multi-circuit protection valve, which connects the output of the air dryer with at least one external compressed air storage and external compressed air consumers pneumatically connects, and a silencer interacts but is arranged separately in relation to each other.

Alternatively, it can be provided that the electric motor, an inverter influencing the operation of the electric motor, the two air compressors, the intercooler, the aftercooler, the air dryer, a multi-circuit protection valve which pneumatically connects the output of the air dryer to at least one external compressed air storage and external compressed air consumers, and a silencer are arranged in or on a common housing.

In the two construction variants described, the device components mentioned are connected to one another in a suitable manner via the electrical, pneumatic and hydraulic connecting lines mentioned and possibly arranged in the housing. As a result, the compressed air generating device is extremely compact, easy to assemble during production and easy to attach to a motor vehicle, for example a commercial vehicle.

In this context, it can further be provided that a control and regulating device is additionally arranged separately in or on the housing of the compressed air generating device, that the control and regulating device is connected to the inverter for controlling the electric motor via a first control line, that the control and control device is connected via a second control line to a 3/2-way solenoid switching valve, which is used to open or close a regeneration line that at least indirectly pneumatically connects the compressed air storage and the air dryer, and that the control and regulating device is connected to the multi-circuit protection valve via a sensor line is.

Due to the additional integration of the control and regulating device, the 3/2-way solenoid switching valve as well as the associated control lines and the regeneration line into the housing of the compressed air generating device, this contains further components assigned to the compressed air generating device, which makes the entire system even easier to handle and easier to connect to the motor vehicle . Therefore, if one of its components malfunctions, such a compressed air generating device can easily be removed as a whole from a commercial vehicle and sent to a repair shop, while a new compressed air generating device is quickly and easily installed on the motor vehicle. Since a compressed air generating device is an operationally necessary device, especially in commercial vehicles, the procedure described avoids lengthy repairs and the commercial vehicle can be put back into use quickly.

In order to further improve the repairability of the compressed air generating device and to enable quick repairs, according to another development of the compressed air generating device it can be provided that it is constructed from four modules, which, together with the associated pneumatic, hydraulic and electrical lines, are arranged in or on the common housing are. The electric motor, the inverter, the two air compressors and the control and regulation device are arranged in a compressor module. A compressed air cooling module has the intercooler and the aftercooler, and the air dryer and the multi-circuit protection valve are arranged in a dryer module. Furthermore, a silencer module contains a silencer, this silencer containing a sound-absorbing material. The sound-absorbing material is designed in such a way that it can also absorb water droplets separated by the air dryer and, like splash water introduced into the silencer, can direct it to a water outlet of the silencer module. In addition, at least one regeneration air outlet opening is designed in the silencer module for discharging regeneration compressed air into the environment. In certain applications, the integration of this silencer module can be dispensed with.

The compressed air generating device with the features of the invention can be constructed in detail in such a way that an outlet of the air dryer is connected via a first check valve closing in the direction of the air dryer by means of a fifth compressed air line, that this fifth compressed air line via the mentioned multi-circuit protection valve to the at least one compressed air reservoir and to compressed air consumers means that a regeneration compressed air inlet of the air dryer has a second check valve opening towards the regeneration compressed air inlet, an orifice and a first line branch with the output of a 3/2-way solenoid
switching valve is connected, that the input of this 3/2-way solenoid switching valve is connected to the fifth compressed air line via a regeneration compressed air line, that when the 3/2-way solenoid switching valve is actuated, the air dryer is connected to the first line branch via this 3/2-way solenoid switching valve , the aperture and the first check valve dry compressed air can be supplied as regeneration compressed air, and that regeneration compressed air can also be supplied to the pneumatic control input of a 2/2-way switching valve when the 3/2-way solenoid switching valve is actuated, which is assigned to a regeneration air outlet of the air dryer.

A regeneration process on the air dryer is therefore initiated by the control and regulation device and is largely controlled using the 3/2-way solenoid switching valve. By means of the 3/2-way solenoid switching valve, dry regeneration compressed air is directed to the air dryer, and at the same time a control pressure is fed to a control pressure input of the pneumatic 2/2-way switching valve to open a regeneration air outlet of the air dryer. This control pressure is generated by a small portion of the regeneration compressed air, which comes from the compressed air storage and is also directed into the air dryer for drying the desiccant there.

Another development provides that the pressure-controlled 2/2-way switching valve is also assigned to the collecting area of the air dryer, the pneumatic control input of which is connected to the output of the 3/2-way solenoid switching valve via a second line branch. The 2/2-way switching valve is designed in such a way that it is closed in the unactuated state. The 2/2-way switching valve can also be switched from its closed position to its open position by means of regeneration compressed air supplied to the air dryer and via the second line branch. When the 2/2-way switching valve is open, dry regeneration compressed air can be passed through the desiccant of the air dryer in a regeneration compressed air stream. After flowing through the drying agent, the regeneration compressed air can be directed into the collecting area of the air dryer and can entrain any condensed water that has accumulated there and remove it from it via at least one regeneration air outlet on the air dryer.

It can also be provided that instead of the 3/2-way solenoid switching valve, two of the Control and regulating device controllable 2/2-way solenoid switching valves are present, the first 2/2-way solenoid switching valve being arranged in the flow direction of regeneration compressed air in front of the orifice in the first line branch, with the second 2/2-way solenoid switching valve in front the pressure-controlled 2/2-way switching valve is arranged in the second line branch, and wherein the fifth compressed air line is connected directly to the first line branch and directly to the second line branch in the flow direction of regeneration compressed air in front of the two 2/2-way solenoid switching valves.

In addition, according to another advantageous development, the compressed air generating device has an ambient temperature sensor with which the ambient temperature can be measured. This ambient temperature sensor is also connected to the control and regulation device via a data or sensor line. Determining and taking into account the ambient air temperature is advantageous because the moisture content of the ambient air that can be sucked in by the compressed air generating device depends on the air temperature. At a low air temperature, its water content can be lower than at a higher temperature. It should also be taken into account that the ambient air temperature influences the temperature of the compressed air reservoir and the compressed air stored therein from which a regeneration compressed air volume is taken during regeneration operation. As a result, the ambient temperature also influences the moisture absorption capacity of the regeneration compressed air as it flows through the desiccant of the air dryer.

The data or sensor lines mentioned here can be CAN bus lines.

The invention also relates to a method for operating a compressed air generating device with the features of at least one of the device claims and the above device description. According to the method, compressed air is cooled in at least one air cooler by means of the at least one air compressor. The cooled compressed air is then fed to an air dryer and dried there in order to then be directed to compressed air consumers and/or at least one compressed air storage. During a regeneration operation of the compressed air generating device, in order to regenerate a desiccant arranged in the air dryer, dry compressed air to the extent of the necessary regeneration compressed air volume is passed through the desiccant and then discharged into the environment.

It is provided here that the regeneration compressed air volume required for the regeneration of the desiccant is calculated at least as a function of the temperature that the coolant has before and/or after it flows through the air cooler that is arranged as the last air cooler in front of the air dryer, and that this is then done in such a way A certain regeneration compressed air volume of dry compressed air is passed through the air dryer.

Since the amount of water that the compressed air carries as air humidity after passing through the last air cooler to the air dryer depends on the compressed air temperature there, it may initially seem disadvantageous not to base the regeneration compressed air volume necessary for regeneration operation of the compressed air generating device on the basis of a direct measurement Determine the temperature of the compressed air stream in front of the air dryer.

However, the procedure presented here has the advantage that no additional temperature sensor is necessary to obtain information about what temperature the compressed air has before it reaches the air dryer and what water content in the form of air humidity this compressed air carries with it. As already explained above, today in every motor vehicle with a liquid cooling system the coolant temperature is measured after leaving the radiator by means of a temperature sensor and its measured values are made available in the motor vehicle for a variety of purposes, for example via a CAN data bus. Knowing the temperature of the coolant directly after leaving the vehicle radiator or immediately before the air cooler mentioned, the temperature of the compressed air after leaving this air cooler can be inferred indirectly without requiring a separate temperature sensor.

The operation of the compressed air generating device and in particular the supply of the coolant are then regulated so that the cooling effect of the last air cooler before the air dryer is maximum. As a result, the compressed air in front of the air dryer is cooled to the maximum, so that the compressed air only contains comparatively little moisture that puts a strain on the air dryer. As a result, the desiccant of the air dryer must be regenerated less frequently or with less regeneration compressed air volume.

In a further embodiment of the method it is provided that the coolant temperature is measured in front of the coolant inlet opening of the compressed air generating device by means of a first temperature sensor, and that this is for drying of the desiccant in the air dryer, the required regeneration compressed air volume is controlled and / or regulated through the air dryer depending on the measured coolant temperature.

Alternatively, it can be provided that the coolant temperature is measured directly in front of the coolant inlet of the air cooler, which is arranged as the last air cooler in front of the air dryer in the flow direction of the compressed air, by means of a second temperature sensor, and that the volume of regeneration compressed air required for drying the desiccant in the air dryer in each case Depending on the measured coolant temperature, it is controlled and / or regulated through the air dryer.

Furthermore, it can also be provided that the coolant temperature behind the coolant outlet of the air cooler is measured by means of a third temperature sensor, which is arranged as the last air cooler in front of the air dryer in the direction of flow of the compressed air, and that the regeneration compressed air volume required for drying the desiccant in the air dryer depends on controlled and/or regulated by the measured coolant temperature through the air dryer.

Another possibility for determining an optimally sufficient volume of regeneration compressed air for drying the desiccant of the air dryer provides that the temperature of an inverter used to control and regulate the electric motor is measured and that the measured temperature of the inverter is used to calculate the coolant temperature in the air cooler which is arranged as the last air cooler in front of the air dryer in the direction of flow of the compressed air, and that the regeneration compressed air volume required for drying the desiccant in the air dryer is passed through the air dryer in a controlled and / or regulated manner depending on the coolant temperature determined in this way.

The temperature of its electronics can be used as the temperature of the inverter. With this method variant, the arrangement of a temperature sensor in the area of the coolant lines and/or the air cooler mentioned can be dispensed with in a cost-saving manner.

1. a) Ansaugen von Umgebungsluft mittels des ersten Luftverdichters,
2. b) Vorverdichten der angesaugten Umgebungsluft in dem ersten Luftverdichter auf einen ersten Luftdruckwert,
3. c) Kühlen eines Zwischenkühlers mit einem flüssigen Kühlmittel,
4. d) Abkühlen der vorverdichteten Druckluft in dem Zwischenkühler,
5. e) weiteres Verdichten der Druckluft auf einen zweiten, höheren Druckwert mittels eines zweiten Luftverdichters,
6. f) Kühlen eines Nachkühlers mit dem flüssigen Kühlmittel, wobei der Nachkühler in Strömungsrichtung des Kühlmittels gesehen als erster Luftkühler von dem Kühlmittel hydraulisch erreicht wird,
7. g) Abkühlen der in dem zweiten Luftverdichter weiter komprimierten Druckluft in dem Nachkühler,
8. h) Trocknen der gekühlten Druckluft in einem Lufttrockner,
9. i) Weiterleiten der gekühlten und getrockneten Druckluft an Druckluftverbraucher und/oder an zumindest einen Druckluftspeicher.

According to a further specialization of the process, the following process steps can be provided:

1. a) sucking in ambient air using the first air compressor,
2. b) pre-compressing the sucked-in ambient air in the first air compressor to a first air pressure value,
3. c) cooling an intercooler with a liquid coolant,
4. d) cooling the pre-compressed compressed air in the intercooler,
5. e) further compressing the compressed air to a second, higher pressure value using a second air compressor,
6. f) cooling an aftercooler with the liquid coolant, the aftercooler being the first air cooler to be reached hydraulically by the coolant, viewed in the flow direction of the coolant,
7. g) cooling the compressed air further compressed in the second air compressor in the aftercooler,
8. h) drying the cooled compressed air in an air dryer,
9. i) forwarding the cooled and dried compressed air to compressed air consumers and/or to at least one compressed air storage.

These process steps make it clear that the compressed air that has left the second air compressor is cooled as it flows through the aftercooler to the extent that the freshly supplied liquid coolant allows. For this purpose, it is provided that the liquid coolant is not used as in the compressed air generating device according to DE 10 2039 139 424.6 is first directed to a cooling device of the electric motor or to the intercooler in order to cool it during operation. In the compressed air generating device presented here, the coolant is first directed to the aftercooler in order to cool it and, as a result, the compressed air as much as possible. This makes it possible according to the method to cool the compressed air generated so much before it reaches the air dryer that as much moisture as possible is separated and drained away from the compressed air.

1. j) Weiterleiten des flüssigen Kühlmittels von dem Nachkühler zu dem Zwischenkühler,
2. k) Weiterleiten des flüssigen Kühlmittels von dem Zwischenkühler zu einer Kühlvorrichtung des Elektromotors,
3. l) Weiterleiten des flüssigen Kühlmittels von der Kühlvorrichtung des Elektromotors zu einer Kühlvorrichtung des zweiten Luftverdichters,
4. m) Weiterleiten des flüssigen Kühlmittels von der Kühlvorrichtung des zweiten Luftverdichters zu einer Kühlvorrichtung des Wechselrichters,
5. n) Weiterleiten des flüssigen Kühlmittels von der Kühlvorrichtung des Wechselrichters zu einer Kühlvorrichtung des ersten Luftverdichters,
6. o) Weiterleiten des flüssigen Kühlmittels von der Kühlvorrichtung des ersten Luftverdichters zu einer externen Kühlvorrichtung.

In order to also cool other components of the compressed air generating device with the liquid coolant, the following further process steps are provided in addition to the method mentioned:

1. j) forwarding the liquid coolant from the aftercooler to the intercooler,
2. k) forwarding the liquid coolant from the intercooler to a cooling device of the electric motor,
3. l) forwarding the liquid coolant from the cooling device of the electric motor to a cooling device of the second air compressor,
4. m) forwarding the liquid coolant from the cooling device of the second air compressor to a cooling device of the inverter,
5. n) forwarding the liquid coolant from the cooling device of the inverter to a cooling device of the first air compressor,
6. o) forwarding the liquid coolant from the cooling device of the first air compressor to an external cooling device.

In addition to guiding the coolant, especially first to the aftercooler, and guiding the compressed air in the compressed air generating device, the regeneration of the drying agent of the air dryer is particularly important. During this regeneration, the drying agent, which has removed atmospheric moisture from the supplied compressed air in previous drying processes and has now greatly reduced its drying ability, is flowed through in the opposite direction by temporarily stored dry compressed air. The compressed air takes water from the desiccant and flows loaded with it out of the air dryer into the environment. The frequency with which such regeneration processes must be carried out and the volume of compressed air required for these regeneration processes influence the need for compressed air to be generated by the compressed air generating device when a vehicle is operating. Since during the cooling of the compressed air described above, water is already separated from the compressed air in the aftercooler, this reaches the entrance area as a film of water or as small droplets with the compressed air directed to the air dryer, from which it is discharged into the environment.

However, it can just as easily be provided that the time interval between two regeneration processes for drying the desiccant of the air dryer is controlled and/or regulated depending on the temperature of the coolant which the coolant has at the outlet of the external cooling device or at the inlet of the aftercooler.

Since the temperature of the coolant is decisive for how much water has already condensed out of the compressed air supplied to the aftercooler, a comparatively low coolant temperature causes a comparatively large separation of water from the compressed air already at the aftercooler, which is drained from there. As a result, the desiccant of the air dryer is less heavily loaded, so that the regeneration compressed air volume can be lower or, for example, the time interval between two regeneration processes can be greater than at a comparatively high coolant temperature.

The ambient temperature of a vehicle must also be taken into account when carrying out regeneration processes of the type described, because the compressed air stored in a compressed air reservoir takes on the ambient temperature over the wall of the compressed air reservoir after some time. Since the compressed air stored in this compressed air storage is also used for the regeneration of the desiccant in the air dryer and the compressed air temperature determines the water storage capacity of the regeneration compressed air, knowledge of the ambient temperature is important for determining the necessary regeneration compressed air volume.

Therefore, in the method in which previously dried and temporarily stored compressed air is passed through the air dryer as regeneration compressed air in the opposite direction to regenerate a desiccant arranged in the air dryer, it can be provided that the volume of regeneration compressed air required for drying the desiccant depends on the average Ambient temperature is controlled and/or regulated.

It can also be provided in this method that the time interval between two regeneration processes for drying the desiccant of the air dryer is controlled and/or regulated as a function of the average ambient temperature. The average value of the ambient temperature can be determined over a predetermined period of time.

For example, if both the ambient temperature and the coolant temperature change quickly due to the current driving situation and/or rapidly changing environmental conditions, it can be provided that the regeneration compressed air volume required for drying the desiccant or the duration and/or frequency of the regeneration processes in Depending on the difference between the ambient temperature and the coolant temperature is controlled and regulated.

In the case of an unregulated control of the regeneration of the desiccant of the air dryer, according to another development of the method for operating the compressed air generating device presented, it is provided that a maximum temperature value of the coolant to be expected during operation of the compressed air generating device is determined, that this value of the coolant temperature is used as the basis for determining a maximum regeneration compressed air volume is used, and that a relevant regeneration process for the desiccant is carried out with this maximum regeneration compressed air volume.

For a better understanding of the invention, the description is accompanied by a drawing, the only figure of which shows a compressed air generating device with the features of an invention. In this schematic drawing, pneumatic lines that carry air or compressed air are shown with a solid line. Hydraulic lines that transport a liquid coolant are shown with a dashed line and electrical lines with a dotted line.

In the exemplary embodiment shown here, the compressed air generating device 2 has a closed but also openable housing 6, in which the components of the compressed air generating device 2 are combined into modules which are arranged one behind the other. The compressor 4, comprising an electric motor 24 including two drive shafts 30, 32, an inverter 26, a first air compressor 16, a second air compressor 18 and a control and regulating device 28, is arranged in a compressor module 90. Behind it, a compressed air cooling module 92 is arranged in the housing 6, which has an intercooler 20 and an aftercooler 22. These two air coolers 20, 22 serve to cool the compressed air generated by the compressor 4. For this purpose, the two air coolers 20, 22 use a liquid coolant which is supplied by an external cooling device 82. In the example chosen, this external cooling device 82 is a cooling device of a commercial vehicle with a suitable heat exchanger, not shown here. The amount of liquid coolant passed every second through the coolable components of the compressed air generating device 2 can be adjusted by means of a controllable coolant pump, which is controllably connected to the control and regulating device 28.

Below is a dryer module 94 in the housing 6, in which an air dryer 40 and, in the example shown, advantageously a multi-circuit protection valve 50 are arranged. The air dryer 40 contains a drying agent 41 with which atmospheric moisture can be removed from the compressed air fed to the air dryer 40. The drying agent 41 can release this moisture back into dry air, namely when dry compressed air is passed through the air dryer 40 in the opposite direction during a regeneration process. The multi-circuit protection
Valve 50 does not have to be part of the dryer module 94, but its arrangement in the common housing 6 is advantageous. By means of the multi-circuit protection valve 50, it is possible to selectively deliver compressed air released by the air dryer 40 to different compressed air consumers 51, 52 and/or to a compressed air storage 45. In addition, it should be mentioned that the sixth compressed air line DL6 and seventh compressed air line DL7 leading to the compressed air consumers 51, 52 can also be connected to other compressed air storage units on the way there. Likewise, at least one further compressed air consumer, not shown, can be connected to the compressed air storage 45 shown.

Finally, the compressed air generating device 2 has a silencer module 96, which is designed as a silencer 43 which contains a sound-absorbing material 44. This sound-absorbing material 44 is able to dampen sound emissions that arise during a regeneration process when moisture-laden compressed air is released from the air dryer 40. For this purpose, the silencer module 96 has a plurality of regeneration air outlet openings, of which only one regeneration air outlet opening 34 is shown, through which exhaust air AL can be released into the environment. In addition, the silencer module 96 or the silencer 43 has at least one water outlet opening 36 at its deepest point, through which water droplets separated from the compressed air in the air dryer 40 during normal operation and / or through the regeneration air outlet opening.
Spray water that has penetrated into voltage 34 can be removed via a water separation path 80 that forms. The silencer module 96 or at least its silencer 43 can be easily replaced in or on the housing 6.

The components of the four modules 90, 92, 94, 96 described are connected to the extent necessary via pneumatic, hydraulic and electrical lines, which will be discussed separately in the description of the method for operating the compressed air generating device 2.

• Der Betrieb des Kompressors 4 wird mittels des schon erwähnten Steuer- und Regelgerätes 28 gesteuert und geregelt. Das Steuer- und Regelgerät 28 ist über eine Niederspannungsleitung 57 mit einer nicht weiter dargestellten Niederspannungsquelle, mit einer Daten- oder Sensorleitung 59 eines fahrzeugeigenen Datenkommunikationssystems, wie beispielsweise einem CAN-Bus, und mit wenigstens einer Sensorleitung 54 verbunden. Die Sensorleitung 54 führt zu einem am Wechselrichter 26 angeordneten Sensor, beispielsweise ein nicht dargestellter Temperatursensor. Dieser Sensor wird ebenfalls über die Niederspannungsleitung 57 mit einer elektrischen Spannung versorgt. Der den Betrieb der Elektromaschine 24 beeinflussende Wechselrichter 26 steht über eine Hochspannungsleitung 58 mit der nicht gesondert dargestellten elektrischen Spannungsquelle in Verbindung.

The functionality and interaction of the components of the compressed air generating device 2 are as follows:

• The operation of the compressor 4 is controlled and regulated by means of the control and regulating device 28 already mentioned. The control and regulating device 28 is connected via a low-voltage line 57 to a low-voltage source (not shown), to a data or sensor line 59 of a vehicle-specific data communication system, such as a CAN bus, and to at least one sensor line 54. The sensor line 54 leads to one arranged on the inverter 26 Sensor, for example a temperature sensor, not shown. This sensor is also supplied with an electrical voltage via the low-voltage line 57. The inverter 26, which influences the operation of the electric machine 24, is connected via a high-voltage line 58 to the electrical voltage source, not shown separately.

To start and operate the electric motor 24 of the compressor 4, it is controlled in the desired manner by means of the control and regulating device 28 and the inverter 26. This causes the two drive shafts 30, 32 of the electric motor 24 to rotate. The first drive shaft 30 is connected to the first air compressor 16 and the second drive shaft 32 to the second air compressor 18 in a driving manner. The two air compressors 16, 18 are known spiral compressors. The first air compressor 16 is connected to the ambient air L on the input side via an air inlet opening 8 in the housing 6. When the first air compressor 16 is operating, it sucks in ambient air L and compresses it into compressed air with a first air pressure value.

The first air compressor 16 is pneumatically connected on the output side via a first compressed air line DL1, the intercooler 20 and then via a second compressed air line DL2 to the inlet of the second air compressor 18. The intercooler 20 cools the precompressed compressed air, whereby water is condensed out and removed if necessary. In the second air compressor 18, the cooled compressed air is then further compressed to a desired second, higher air pressure value and then fed to the already mentioned aftercooler 22 via a third compressed air line DL3. The compressed air is further cooled in the aftercooler 22. Water condenses from the compressed air.

From the outlet of the aftercooler 22, the cooled and still residually moist compressed air reaches an inlet-side collecting area 49 of the air dryer 40 via a fourth compressed air line DL4. The already condensed water also reaches this collecting area 49 of the air dryer 40 in the form of entrained small droplets or as a film of water. From there, the water is excreted from the air dryer 40 via the regeneration air outlet 42 during a later regeneration process. As a result, the condensed water did not get into the drying agent 41 of the air dryer 40, as is also schematically illustrated in the only drawing figure with small droplets. The compressed air, which has been partially dewatered in this way and is still still moist, arrives from the short fourth compressed air line DL4 into the drying agent 41 of the air dryer 40, flows through this drying agent 41 in a drying air stream 23 and is dried there. The desiccant 41 is able to remove atmospheric moisture from the supplied compressed air and release it back into dry air during a later regeneration process.

The dried compressed air then leaves the air dryer 40 via a spring-loaded first check valve 29, which shuts off in the direction of the air dryer 40, and then enters a fifth compressed air line DL5. This fifth compressed air line DL5 leads to the multi-circuit protection valve 50, which is controlled at least indirectly by the control and regulating device 28. For this purpose, the multi-circuit protection valve 50 is connected to the control and regulating device 28 via a sensor line 56. Via the multi-circuit protection valve 50, the dried compressed air can be directed, for example, through the already mentioned sixth compressed air line DL6 and a compressed air outlet opening 10 in the housing 6 to the first compressed air consumer 51 and via the mentioned seventh compressed air line DL7 to the second compressed air consumer 52. The multi-circuit protection valve 50 can direct dried compressed air to the at least one compressed air reservoir 45 via an eighth compressed air line DL8. Other compressed air consumers and/or compressed air reservoirs (not shown) can also be supplied with compressed air if necessary via the compressed air storage 45. If necessary, the compressed air stored in the compressed air storage 45 can also be supplied to other compressed air consumers via the multi-circuit protection valve 50 or returned to the fifth compressed air line DL5 for regeneration of the drying agent 41 of the air dryer 40.

If a predetermined air pressure is set in the compressed air consumers 51, 52 and in the at least one compressed air storage 45 and the electric motor 24 of the compressor module 90 is switched off, the drying agent 41 arranged in the air dryer 40 and saturated with moisture can be regenerated, i.e. from that stored there water to be freed. For this purpose, the compressed air generating device 2 has a regeneration line DL5a. This regeneration line DL5a is connected via the fifth compressed air line DL5 at least to the eighth compressed air line DL8 leading to the compressed air storage 45 and to the air dryer 40. A 3/2-way solenoid switching valve 72 is arranged in the regeneration line DL5a, which can be controlled by the control and regulation device 28 and is connected to it via a control line 55.

When the 3/2-way solenoid switching valve 72 is not actuated, the regeneration line DL5a is closed, so that no compressed air is passed through it multi-circuit protection valve
til 50 can get from the compressed air storage 45 to the air dryer 40. To carry out a regeneration operation of the air dryer 40, the 3/2-way magnetic
Switching valve 72 is actuated, as a result of which the regeneration line DL5a is opened. As a result, part of the dried compressed air from the compressed air reservoir 45 passes through a first line branch DL5b of the regeneration line DL5a to an aperture 75. There the dried compressed air is expanded, whereby it takes up a larger volume. The compressed air then passes through a second spring-loaded check valve 76 and then reaches the air dryer 40 via a regeneration compressed air inlet 70. The relaxed compressed air then flows through the air dryer 40 and the drying agent 41 arranged there in a regeneration compressed air stream 77, provided that a pressure-controlled pressure-controlled 2/ 2-way switching valve 39 on the collecting area 49 of the air dryer 40 is open.

To operate this pressure-controlled 2/2-way switching valve 39, another part of the dried compressed air behind the outlet of the 3/2-way solenoid switching valve 72 is passed through a second line branch DL5c to this pressure-controlled 2/2-way switching valve 39. The pressure-controlled 2/2-way switching valve 39 is constructed in such a way that in its unactuated switching position it closes a connection from the collecting area 49 of the air dryer 40 to a regeneration air outlet 42 of the air dryer 40 and opens it in the actuated switching state. Accordingly, the pressure-controlled 2/2-way switching valve 39 is opened when the 3/2-way solenoid switching valve 72 has also been switched to its open position.

According to an alternative embodiment, it is provided that instead of the 3/2-way solenoid switching valve 72, there are two 2/2-way solenoid switching valves that can be controlled by the control and regulating device 28. These two 2/2-way solenoid switching valves are not shown in the drawing, but their arrangement can be easily understood by a person skilled in the art based on the following description. The first 2/2-way solenoid switching valve is arranged in the flow direction of the regeneration compressed air in front of the aperture 75 in the first line branch DL5b and the second 2/2-way solenoid switching valve is in front of the pressure-controlled 2/2-way switching valve 39 in the second line branch DL5c arranged. In addition, the fifth compressed air line DL5 is connected directly to the first line branch DL5b and directly to the second line branch DL5c in the direction of flow of regeneration compressed air in front of the two 2/2-way solenoid switching valves.

As soon as these two 2/2-way solenoid switching valves are switched to their open position, the pressure-controlled 2/2-way switching valve can also be opened.
valve 39 dry regeneration compressed air is passed through the air dryer 40 into the silencer 43 in order to dry the desiccant 41.

By means of this structure, when the first 2/2-way solenoid switching valve is closed, the second 2/2-way solenoid switching valve is open and the pressure-controlled 2/2-way switching valve 39 is therefore open, the collecting area 49 of the air dryer 40 can be supplied with compressed air supplied via the aftercooler 22 can be advantageously freed from water W that has accumulated there.

When the 2/2-way switching valve 39 is open under pressure control, the relaxed compressed air flows through the drying agent 41 in the mentioned regeneration compressed air stream 77 in the direction of the silencer 43. Moisture is removed from the drying agent 41. The compressed air enriched with moisture in this way as well as the water that has already condensed and accumulated in the collecting area 49 of the air dryer 40 then leaves the air dryer 40 via its regeneration air outlet 42 and thus reaches the silencer 43.

The moist exhaust air AL then flows through the sound-absorbing material 44 arranged in the silencer 43 via an exhaust air path 78 to the at least one regeneration air outlet opening 34 of the silencer 43 of the compressed air generating device 2. Water droplets that may have formed in the regeneration compressed air flow or in the sound-absorbing material 44 of the silencer 43 when the regeneration compressed air flow flows through there, as well as the condensed water from the collecting area 49 of the air dryer 40, flow in the silencer 43 via the already mentioned water separation path 80 to the at least one water outlet opening 36 of the silencer 43. The water outlet opening 36 of the silencer 43 but also serves to remove any splash water that may have penetrated into the silencer 43 via the at least one regeneration air outlet opening 34.

The regeneration process is ended when a predetermined, sufficiently large volume of regeneration compressed air has flowed through the drying agent 41 of the air dryer 40 in order to be able to use it for a further air drying phase.

Of great importance for the inventive structure of the compressed air generating device 2 is the flow path of the external cooling device 82 supplied liquid coolant. This coolant is cooled to a predetermined temperature in the external cooling device 82 and supplied to the compressed air generating device 2 via a coolant supply line Kin. The cooling activity of the external cooling device 82 is controlled and regulated with a control and regulating device 28. In a preferred control of the temperature of the coolant, the current actual temperature of the coolant is measured with a first temperature sensor 73 at the output of the cooling device 82, and the coolant temperature is then regulated to a predetermined setpoint of the coolant temperature. For this purpose, the first temperature sensor 73 is connected to the control and regulating device 28 via the data and/or sensor line 59 of the CAN bus.

The coolant passes from the external cooling device 82 through a coolant inlet opening 12 into the compressed air generating device 2 and into the compressed air cooling system.
dul 92. The coolant then flows through a first coolant line KL1 into the aftercooler 22 in order to cool the compressed air generated by the compressor 4 as much as possible. Since the coolant is first passed into the aftercooler 22, the lowest temperature of the coolant that it has within the compressed air generating device 2 can be used. As a result, the compressed air is cooled comparatively strongly before it enters the air dryer 40, as a result of which some of the air moisture carried condenses out and is at least partially separated in the aftercooler 22. The condensed water is also passed into the collecting area 49 of the air dryer 40 and from there discharged into the environment directly or via the silencer 43. This process removes a lot of moisture from the compressed air before it reaches the air dryer 40. This is all the more the lower the temperature of the coolant.

As a result, the desiccant 41 of the air dryer 40 needs to be dried less frequently in regeneration operations compared to conventional compressed air generating devices, or such regeneration operations may be performed with a smaller volume of regeneration compressed air than usual. As a result, more of the dry compressed air stored in the compressed air storage 45 is available for the compressed air consumers 51, 52, so that the electric motor 24 of the compressor 4 of the compressed air generating device 2 has to be in operation less frequently. As a result, for example when arranging and operating such a compressed air generating device 2 in a vehicle, the consumption of electrical energy is reduced, which reduces the vehicle's exhaust emissions and thus its CO ₂ emissions.

The frequency of the regeneration processes or the respectively required regeneration compressed air volume can therefore be smaller, the lower the temperature of the coolant at the inlet of the aftercooler 22. It is therefore advantageous if the regulation of the frequency of actuation and/or the regulation of the duration of actuation of the 3/2-way solenoid switching valve 72 by means of the control and regulating device 28 also takes place as a function of the temperature of the coolant. For this purpose, as already briefly mentioned, according to the exemplary embodiment shown in the single figure, a first temperature sensor 73 is arranged in the area of the outlet of the external cooling device 82 or in the area of the coolant inlet opening 12, by means of which the temperature of the liquid coolant can be measured. Typically, such a temperature sensor 73 is already a component of the cooling device 82. The temperature measurements obtained in this way can be routed to the control and regulating device 28 via the data and/or sensor line 59 mentioned. The control and regulating device 28 then controls and regulates the regeneration of the desiccant 41 of the air dryer 40, taking into account the current coolant temperature, directly via the frequency of actuation and/or the duration of actuation of the 3/2-way solenoid switching valve 72 and indirectly by means of the pressure-controlled 2/2 -way switching valve 39.

As the only figure shows as an alternative solution, the temperature of the coolant can also be measured at the coolant inlet of the aftercooler 22 by means of a second temperature sensor 73 'and / or at the coolant outlet of the aftercooler 22 by means of a third temperature sensor 73", which is also via the data and/or sensor line 59 are connected to the control and regulating device 28. The data and/or sensor line 59, which is connected to the respective temperature sensor 73 ', 73", can also be completely within the other than shown in the single figure Compressed air generating device 2 may be arranged.

With such a control, it should also be noted that the temperature of the coolant can fluctuate during operation of the compressed air generating device 2. This can be caused by different load conditions of the vehicle and its systems and/or by rapidly changing ambient temperatures. Since the current temperature of the coolant is measured with the first temperature sensor 73 in most vehicles in order to regulate the external cooling device 82 mentioned, its current value is available to the control and regulating device 28 via the already mentioned data and/or sensor line 59 of the CAN bus available. Based on the current value of the temperature of the coolant, the control and regulating device 28 can therefore at any time The duration of operation of the 3/2-way solenoid switching valve 72 and thus the frequency and duration of a regeneration process on the dryer 40 can be quickly controlled and regulated depending on the temperature.

Since in most vehicles on the road today the ambient temperature of the vehicle is also measured by means of an ambient temperature sensor 74 and displayed with a display element, the ambient temperature also represents the control and regulation of the operating time of the 3/2-way magnetic switching
valve 72 and thus for controlling and regulating the frequency and duration of a regeneration process on the air dryer 40 is available to the control and regulating device 28 via the data and / or sensor line 59 of the CAN bus.

The ambient temperature of the vehicle is also of particular importance for the control and regulation of the regeneration processes, since the compressed air, after it has been dried in the dryer 40, cools further down to the temperature of the compressed air container 45 or the compressed air consumers 51, 52, which generally corresponds to the ambient temperature exhibit. During this further cooling process, the relative humidity in the compressed air increases again. To ensure that excessive air humidity does not lead to corrosion processes in the compressed air storage tanks and compressed air consumers when ambient temperatures are low in relation to the coolant temperature, or even water condenses out and freezes into ice, the degree of drying of the compressed air must ideally also take the current ambient temperature into account.

This degree of drying can be adjusted via the regeneration compressed air volume used in a regeneration process and/or via the frequency of the regeneration processes in a period under consideration. If, for example, a volume of regeneration compressed air that is actually too large is used during a regeneration process, the drying agent 41 becomes drier than is required according to previously known practice. During a subsequent conveying process, the compressed air passed through the air dryer 40 will lose more moisture than previously necessary, as a result of which the compressed air has a higher degree of drying when it leaves the air dryer 40. When the compressed air then cools down further in a compressed air container or in a compressed air consumer, the degree of drying of the compressed air is then advantageously uncritically high, so that condensation and possibly ice formation do not occur there.

The regeneration compressed air volume and/or the frequency of the regeneration processes is controlled and regulated by means of the control and regulating device 28 at a constant ambient temperature depending on the temperature of the coolant, and at a constant temperature of the coolant depending on the ambient temperature. If both the ambient temperature and the coolant temperature change, the duration and/or frequency of the regeneration processes is controlled and regulated depending on the difference between the two temperatures mentioned.

If such a regulation is omitted, the volume of regeneration compressed air required for a regeneration process must also cover the most unfavorable case, i.e. the highest coolant temperature to be expected during operation of the compressed air generating device 2. As a result, such a regeneration process for the drying agent 41 would always take place with a previously determined maximum regeneration compressed air volume.

After the liquid coolant has flowed through the aftercooler 22, it reaches the intercooler 20 mentioned via a second coolant line KL2. There it cools the compressed air precompressed by the first air compressor 16. After cooling the pre-compressed compressed air in the intercooler 20, the liquid coolant is conducted via a third coolant line KL3 to a cooling device 25 of the electric motor 24. There the coolant cools, for example, the stator of the electric motor 24.

The coolant then flows through a fourth coolant line KL4 to a cooling device 48 of the second air compressor 18 of the compressor 4, which is thereby cooled during its compression activity. The coolant then flows through a fifth coolant line KL5 to a cooling device 27 of the inverter 26 in order to cool it. The coolant is then passed through a sixth coolant line KL6 to a cooling device 46 of the first air compressor 16 of the compressor 4 in order to cool this too. Finally, the heated coolant is passed through a coolant outlet opening 14 from the compressor module 90 and from the housing 6 of the compressed air generating device 2 via a coolant discharge line Kout to the external cooling device 82.

• In diesem Fall ist eine erfindungsgemäß ausgebildete Drucklufterzeugungsvorrichtung 2 in einem Lastkraftwagen eingebaut und sie nutzt zur Kühlung des genannten flüssigen Kühlmittels das Kühlsystem, welches auch den Verbrennungsmotor des Lastkraftwagens kühlt. Bei einem Kaltstart des Verbrennungsmotors, also einem Starten desselben bei sehr niedriger Umgebungstemperatur, ist es hinsichtlich der Betriebseigenschaften einer Fahrzugbatterie, hinsichtlich geringer Abgasemissionen des Lastkraftwagens sowie hinsichtlich der Bereitstellung von Warmluft mittels einer Innenraumheizung des Lastkraftwagens vorteilhaft, wenn die Temperatur des Kühlsystems des Verbrennungsmotors schnell über die Umgebungstemperatur erhöht wird. Dadurch, dass bei dem Kaltstart des Verbrennungsmotors auch sogleich die elektrisch betriebene Drucklufterzeugungsvorrichtung 2 zur betriebsnotwendigen Erzeugung von Druckluft in Betrieb genommen wird, wird diese von dem flüssigen Kühlmittel soweit möglich gekühlt. Die dadurch der Drucklufterzeugungsvorrichtung 2 entzogene Abwärme, insbesondere die Wärme, welche durch den Betrieb des Elektromotors 24, des Wechselrichters 26 und der beiden Luftverdichter 16, 18 erzeugt wird, dient dann vorteilhaft über die Erwärmung des flüssigen Kühlmittels indirekt auch für eine Entlastung der Fahrzeugbatterie. Für den Zeitraum des Kaltstarts sowie einer kurzen Warmlaufphase des Lastkraftwagens können dabei an dem Nachkühler 22 und am Eingang des Lufttrockners 40 auch Temperaturen akzeptiert werden, bei welchen sich Wassereis bilden kann. Da die Warmlaufphase vergleichsweise kurz ist, wird in der dann folgenden normalen Betriebsphase sich gegebenenfalls am Nachkühler 22 und am Eingang des Lufttrockners 40 gebildetes Wassereis verdunsten und in der Druckluft als Luftfeuchtigkeit aufgenommen werden.

Investigations have shown that the described comparatively strong cooling of the compressed air in the aftercooler 22 has no negative effects on the operation of the compressed air generating device 2. There are even other benefits that can be seen. This will be explained using the following example:

• In this case, a compressed air generating device 2 designed according to the invention is in installed in a truck and it uses the cooling system to cool the said liquid coolant, which also cools the truck's internal combustion engine. When starting the internal combustion engine cold, i.e. starting it at a very low ambient temperature, it is advantageous in terms of the operating properties of a vehicle battery, in terms of low exhaust emissions from the truck and in terms of the provision of warm air by means of an interior heater in the truck if the temperature of the cooling system of the internal combustion engine rises quickly the ambient temperature is increased. Because the electrically operated compressed air generating device 2 is immediately put into operation for the operational production of compressed air when the internal combustion engine is cold started, it is cooled as far as possible by the liquid coolant. The waste heat thereby removed from the compressed air generating device 2, in particular the heat which is generated by the operation of the electric motor 24, the inverter 26 and the two air compressors 16, 18, then advantageously also serves indirectly to relieve the load on the vehicle battery via the heating of the liquid coolant. For the period of the cold start and a short warm-up phase of the truck, temperatures at which water ice can form can also be accepted at the aftercooler 22 and at the inlet of the air dryer 40. Since the warm-up phase is comparatively short, in the normal operating phase that follows, any water ice formed on the aftercooler 22 and at the inlet of the air dryer 40 will evaporate and be absorbed into the compressed air as atmospheric moisture.

List of reference symbols (part of the description)

2

Compressed air generating device

4

compressor

6

Housing of the compressed air generating device

8th

Air intake opening

10

Compressed air outlet opening

12

Coolant inlet opening

14

Coolant outlet opening

16

First air compressor

18

Second air compressor

20

Intercooler, air cooler

22

Aftercooler, air cooler

23

Drying air flow in the air dryer

24

Electric motor

25

Electric motor cooling device

26

Inverter

27

Inverter cooling device

28

Control and regulating device

29

First check valve

30

First drive shaft

32

Second drive shaft

34

Regeneration air outlet opening

36

Silencer water outlet opening

39

2/2-way switching valve, drain valve on the air dryer

40

Air dryer

41

Desiccant in the air dryer

42

Regeneration air outlet of the air dryer

43

silencer

44

Sound absorbing material

45

Compressed air storage

46

Cooling device of the first air compressor

48

Cooling device of the second air compressor

49

Collection area of the air dryer for water droplets

50

Multi-circuit protection valve

51

First compressed air consumer

52

Second compressed air consumer

54

Sensor line

55

Control line from the control and regulating device to the 3/2-way solenoid switching valve

56

Sensor line from the control and regulating device to the multi-circuit protection valve

57

Low voltage line

58

High voltage line

59

Data or sensor cable, CAN bus

70

Regeneration compressed air inlet of the air dryer

72

3/2-way solenoid switching valve

73

First temperature sensor (coolant measurement)

74

Ambient temperature sensor

75

cover

76

Second check valve

77

Regeneration compressed air flow in the air dryer

78

Exhaust air path in the silencer

80

Water separation path in the silencer

82

External cooling device

90

Compressor module

92

Compressed air cooling module

94

Dryer module

96

Silencer module

L

Ambient air

AL

Exhaust air

Kin

Coolant supply line

Kout

Coolant drain line

W

Water

DL1

First compressed air line

DL2

Second compressed air line

DL3

Third compressed air line

DL4

Fourth compressed air line

DL5

Fifth compressed air line

DL5a

Regeneration compressed air line

DL5b

First line branch

DL5c

Second line branch

DL6

Sixth compressed air line

DL7

Seventh compressed air line

DL8

Eighth compressed air line

KL1

First coolant line

KL2

Second coolant line

KL3

Third coolant line

KL4

Fourth coolant line

KL5

Fifth coolant line

KL6

Sixth coolant line

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed 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.

Cited patent literature

• DE 102018139058 A1 [0002]
• DE 102013003513 A1 [0002]
• EP 3516218 B1 [0002]
• EP 3331738 B1 [0002]
• DE 102004051435 B3 [0004]
• DE 4445972 C2 [0005]
• DE 1020211214246 [0006]
• US 20100303658 A1 [0007]
• DE 112015006955 T5 [0008]
• DE 1020391394246 [0048]

Claims (27)

Compressed air generating device (2), with a control and regulating device (28), with an electric motor (24) that can be controlled and regulated by the control and regulating device (28), with at least one air compressor (16; 18) that can be driven by the electric motor (24) , with an air inlet (8), via which ambient air (L) can be sucked into the at least one air compressor (16; 18), with at least one air cooler (20; 22), which is connected to the outlet of the at least one air compressor (16; 18) is connected, with at least one air dryer (40), which is connected to the output of the at least one air cooler (20; 22), with a coolant inlet opening (12), via which the at least one air cooler (20; 22) and other components of the compressed air generating device (2) a liquid coolant can be supplied, with a coolant outlet opening (14), via which heated coolant can be removed from the compressed air generating device (2), and with at least one temperature sensor (73, 73 ', 73''), which is connected to the control and control device (28) is connected via a data or sensor line (59), characterized in that the temperature sensor (73, 73 ', 73'') for measuring the coolant temperature is arranged in front of the coolant inlet or behind the coolant outlet of that air cooler (22). is, which is arranged as the last air cooler in front of the air dryer (40) in the direction of flow of the compressed air. Compressed air generating device Claim 1 , characterized in that the temperature sensor (73) for measuring the coolant temperature is arranged in front of the coolant inlet opening (12) of the compressed air generating device (2). Compressed air generating device Claim 1 , characterized in that the temperature sensor (73 ') for measuring the coolant temperature is arranged directly in front of the coolant inlet of the air cooler (22), which is arranged as the last air cooler in front of the air dryer (40) in the direction of flow of the compressed air. Compressed air generating device Claim 1 , characterized in that the temperature sensor (73") for measuring the coolant temperature is arranged as the next component behind the coolant outlet of the air cooler (22), which is arranged as the last air cooler in front of the air dryer (40) in the direction of flow of the compressed air. Compressed air generating device (2) according to one Claims 1 until 4 , characterized in that the air cooler (22), which is arranged as the last air cooler in front of the air dryer (40) in the flow direction of the compressed air, is arranged in such a way that the coolant can flow through it first, viewed in the flow direction of the coolant. Compressed air generating device (2) according to one Claims 1 until 5 , which has the following: an electric motor (24), two air compressors (16, 18) which can be driven by the electric motor (24) and act one after the other, an air inlet (8) through which ambient air (L) can be sucked in by means of the first air compressor (16). , two air coolers for cooling the compressed air, which are designed and arranged as an intercooler (20) or as an aftercooler (22), the inlet of the intercooler (20) being pneumatically connected to the outlet of the first air compressor (16), the outlet of the intercooler (20) is pneumatically connected to the inlet of the second air compressor (18), the outlet of the second air compressor (18) being pneumatically connected to the inlet of the aftercooler (22), and wherein the outlet of the aftercooler (22) is connected to the Inlet of an air dryer (40) is pneumatically connected, as well as a coolant inlet opening (12), via which a liquid coolant can be supplied to the intercooler (20) and the aftercooler (22), and a coolant outlet opening (14), via which heated coolant can be removed, characterized in that the aftercooler (22) is arranged in such a way that, viewed in the flow direction of the coolant, the coolant can flow through it first, and that at least one temperature sensor (73, 73 ', 73") is present, which is used to measure the temperature of the coolant is arranged in front of or behind the aftercooler (22) in the direction of flow. Compressed air generating device Claim 6 , characterized in that the electric motor (24), an inverter (26) influencing the operation of the electric motor (24), the two air compressors (16, 18), the intercooler (20), the aftercooler (22), the air dryer (40 ), a multi-circuit protection valve (50), which pneumatically connects the outlet of the air dryer (40) with at least one external compressed air storage (45) and external compressed air consumers (51, 52), and a silencer (43) which interacts but are arranged separately in relation to each other . Compressed air generating device Claim 6 , characterized in that the electric motor (24), an inverter (26) influencing the operation of the electric motor (24), the two air compressors (16, 18), the intercooler (20), the aftercooler (22), the air dryer (40 ), a multi-circuit protection valve (50), which connects the outlet of the air dryer (40) with at least one external compressed air reservoir (45) and external compressed air consumers (51, 52) pneumatically connects, and a silencer (43) is arranged in or on a common housing (6). Compressed air generating device according to one of the Claims 7 or 8th , characterized in that the control and regulating device (28) is arranged separately or in or on the housing (6), that the control and regulating device (28) is connected to the inverter (26) via a first control line (54) for control of the electric motor (24), that the control and regulating device (28) is connected via a second control line (55) to a 3/2-way solenoid switching valve (72), which is used to open or close the compressed air reservoir (45). and the regeneration line (DL5a) which pneumatically at least indirectly connects the air dryer (40), and that the control and regulating device (28) is connected to the multi-circuit protection valve (50) via a sensor line (56). Compressed air generating device according to one of the Claims 6 until 9 , characterized in that in or on the housing (6) there is a compressor module (90), a compressed air cooling module (92), a dryer module (94) and a silencer module (96) together with associated pneumatic, hydraulic and electrical lines are arranged one behind the other, the compressor module (90) having the electric motor (24), the inverter (26), the two air compressors (16, 18) and the control and regulating device (28), the compressed air cooling module (92 ) has the intercooler (20) and the aftercooler (22), the dryer module (94) having the air dryer (40) and the multi-circuit protection valve (50), the silencer module (96) having the silencer (43) with a contains sound-absorbing material (44), and in which the silencer module (96) has at least one regeneration air outlet opening (34) for discharging regeneration compressed air into the environment. Compressed air generating device according to one of the Claims 6 until 10 , characterized in that the outlet of the air dryer (40) is connected via a first check valve (29) closing in the direction of the air dryer (40) by means of a fifth compressed air line (DL5), that the fifth compressed air line (DL5) via the multi-circuit protection valve (50) to the at least one compressed air reservoir (45) and to compressed air consumers (51, 52), a regeneration compressed air inlet (70) of the air dryer (40) via a second check valve (76) opening in the direction of the regeneration compressed air inlet (70), a diaphragm (75) and a first line branch (DL5b) is connected to the output of the 3/2-way solenoid switching valve (72), so that the input of this 3/2-way solenoid switching valve (72) is connected to the fifth compressed air line via a regeneration compressed air line (DL5a). (DL5) is connected so that when the 3/2-way solenoid switching valve (72) is actuated, the air dryer (40) is connected via this 3/2-way solenoid switching valve (72), the first line branch (DL5b), the orifice (75) and the first check valve (76) can be supplied with dry compressed air as regeneration compressed air, that when the 3/2-way solenoid switching valve (72) is actuated, regeneration compressed air can be supplied to the pneumatic control input of a 2/2-way switching valve (39), and that the 2/2 -Way switching valve (39) is assigned a regeneration air outlet (42) of the air dryer (40). Compressed air generating device Claim 11 , characterized in that the air dryer (40) has a collecting area (49), that the inlet of this collecting area (49) is pneumatically connected to the outlet of the aftercooler (22) via the fourth compressed air line (DL4), and that the collecting area (49 ) is designed in such a way that water that has condensed out of the compressed air and is carried along can collect and be removed from there. Compressed air generating device Claim 12 , characterized in that the pressure-controlled 2/2-way switching valve (39) is assigned to the collecting area (49) of the air dryer (40), that the control input of the pressure-controlled 2/2-way switching valve (39) via a second line branch ( DL5c) is connected to the output of the 3/2-way solenoid switching valve (72), that the 2/2-way switching valve (39) is closed in the unactuated state, that the 2/2-way switching valve (39) is closed by means of to the air dryer (40) and the regeneration compressed air supplied via the second line branch (DL5c) can be switched from its closed position to its open position, so that when the 2/2-way switching valve (39) is open by the drying agent (41) of the air dryer (40) in one Regeneration compressed air flow (77) regeneration compressed air can be directed, that the regeneration compressed air can be conducted into the collecting area (49) of the air dryer (40) after flowing through the desiccant (41) and can entrain condensed water that has accumulated there, and that the regeneration compressed air the air dryer (40) can leave via a regeneration air outlet (42). Compressed air generating device according to one of the Claims 9 until 13 , characterized in that instead of the 3/2-way solenoid switching valve (72) there are two 2/2-way solenoid switching valves that can be controlled by the control and regulating device (28), the first 2/2-way solenoid switching valve being in the direction of flow of regeneration compressed air is arranged in front of the aperture (75) in the first line branch (DL5b), whereby the second 2/2-way solenoid switching valve is arranged in front of the pressure-controlled 2/2-way switching valve (39) in the second line branch (DL5c), and the fifth compressed air line (DL5) in the flow direction of regeneration compressed air in front of the two 2/2-way Directional solenoid switching valves are connected directly to the first line branch (DL5b) and directly to the second line branch (DL5c). Compressed air generating device according to one of the Claims 1 until 14 , characterized in that the compressed air generating device (2) has an ambient temperature sensor (74) by means of which the ambient temperature can be measured, and that this ambient temperature sensor (74) is connected to the control and regulating device (28) via a data or sensor line (59). is. Method for operating a compressed air generating device (2) with the features of at least one of the device claims, wherein compressed air is cooled in at least one air cooler (20, 22) by means of the at least one air compressor (16, 18), this cooled compressed air being supplied to an air dryer (40 ) is supplied and dried there, the dried compressed air being supplied to compressed air consumers (51, 52) and / or at least one compressed air storage (45), and in which dry compressed air is used in the circumference for the regeneration of a drying agent (41) arranged in the air dryer (40). a regeneration compressed air volume is passed through it and then discharged into the environment, characterized in that the regeneration compressed air volume necessary for the regeneration of the drying agent (41) is calculated at least as a function of the temperature at which the coolant reaches before and/or after flowing through that air cooler (22 ), which is arranged as the last air cooler (22) in front of the air dryer (40), and that the regeneration compressed air volume of dry compressed air determined in this way is then passed through the air dryer (40). Procedure according to Claim 16 , characterized in that the coolant temperature is measured in front of the coolant inlet opening (12) of the compressed air generating device (2) by means of a first temperature sensor (73), and that the volume of regeneration compressed air required for drying the desiccant (41) in the air dryer (40) depends on the measured coolant temperature is controlled and / or regulated through the air dryer (40). Procedure according to Claim 16 , characterized in that by means of a second temperature sensor (73 '), the coolant temperature is measured immediately in front of the coolant inlet of the air cooler (22), which is arranged as the last air cooler in front of the air dryer (40) in the direction of flow of the compressed air, and that this is for drying of the desiccant (41) in the air dryer (40), the required regeneration compressed air volume is controlled and / or regulated through the air dryer (40) depending on the measured coolant temperature. Procedure according to Claim 16 , characterized in that the coolant temperature is measured behind the coolant outlet of the air cooler (22) by means of a third temperature sensor (73"), which is arranged as the last air cooler in front of the air dryer (40) in the direction of flow of the compressed air, and that this is for drying the Desiccant (41) in the air dryer (40) required regeneration compressed air volume is controlled and / or regulated through the air dryer (40) depending on the measured coolant temperature. Procedure according to Claim 16 , characterized in that the temperature of an inverter (26) present for controlling and regulating the electric motor (24) is measured, that the measured temperature of the inverter (26) is used to calculate the coolant temperature in the air cooler (22) which is in the direction of flow the compressed air is arranged as the last air cooler (22) in front of the air dryer (40), and that the regeneration compressed air volume required for drying the desiccant (41) in the air dryer (40) is controlled and / or regulated by the regeneration compressed air volume depending on the coolant temperature determined in this way Air dryer (40) is passed. Method for operating the compressed air generating device (2) with the features of at least one of the device claims and with the features of at least one of the methods claims 16 until 20 , characterized by the following method steps: a) sucking in ambient air by means of the first air compressor (16), b) pre-compressing the sucked-in ambient air in the first air compressor (16) to a first air pressure value, c) cooling an intercooler (20) with a liquid coolant , d) cooling the pre-compressed compressed air in the intercooler (20), e) further compressing the compressed air to a second, higher pressure value by means of a second air compressor (18), f) cooling an aftercooler (22) with the liquid coolant, the aftercooler (22) in flow direction of the coolant seen as the first air cooler is reached hydraulically by the coolant, g) cooling the compressed air further compressed in the second air compressor (18) in the aftercooler (22), h) drying the cooled compressed air in an air dryer (40), i) Forwarding the cooled and dried compressed air to compressed air consumers (51, 52) and/or to at least one compressed air storage (45). Procedure according to Claim 21 , characterized by the following further method steps: j) forwarding the liquid coolant from the aftercooler (22) to the intercooler (20), k) forwarding the liquid coolant from the intercooler (20) to a cooling device (25) of the electric motor (24) , I) forwarding the liquid coolant from the cooling device (25) of the electric motor (24) to a cooling device (48) of the second air compressor (18), m) forwarding the liquid coolant from the cooling device (48) of the second air compressor (18). a cooling device (27) of the inverter (26), n) forwarding the liquid coolant from the cooling device (27) of the inverter (26) to a cooling device (46) of the first air compressor (18), o) forwarding the liquid coolant from the cooling device (46) of the first air compressor (18) to an external cooling device (82). Procedure according to one of the Claims 16 until 22 , characterized in that the time interval between two regeneration processes for drying the desiccant (41) of the air dryer (40) is controlled and / or regulated depending on the temperature of the coolant which is the coolant at the outlet of the external cooling device (82) or at Inlet of the aftercooler (22). Procedure according to one of the Claims 16 until 23 , characterized in that the time interval between two regeneration processes for drying the desiccant (41) of the air dryer (40) is controlled and / or regulated depending on the ambient temperature. Procedure according to one of the Claims 16 until 24 , characterized in that the regeneration compressed air volume required for drying the drying agent (41) is controlled and/or regulated depending on the ambient temperature. Procedure according to one of the Claims 16 until 25 , characterized in that the regeneration compressed air volume required for drying the drying agent (41) or the duration and/or frequency of the regeneration processes is controlled and/or regulated depending on the difference between the ambient temperature and the coolant temperature. Procedure according to one of the Claims 16 until 26 , characterized in that in the case of an unregulated control of the regeneration of the drying agent (41) of the air dryer (40), a maximum expected temperature value of the coolant during operation of the compressed air generating device (2) is determined, that this value of the coolant temperature serves as the basis for determining a maximum Regeneration compressed air volume is used, and that a related regeneration process for the drying agent (41) is carried out with this maximum regeneration compressed air volume.

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