Compressed air generating plant and method for operating same

Abstract

The invention relates to a compressed air generating device (2), comprising: a control and regulator (28); an electric motor (24) that can be controlled and regulated by a control and regulator (28); at least one air compressor (16; 18) that can be driven by the electric motor (24); an air inlet (8) via which ambient air (L) can be drawn into the at least one air compressor; at least one air cooler (20; 22) connected to the output of the at least one air compressor; at least one air dryer (40) connected to the output of the at least one air cooler; a cooling medium inlet opening (12) via which a liquid cooling medium can be fed to the at least one air cooler and further components of the compressed air generating system; a cooling medium outlet opening (14) via which the heated cooling medium can be discharged from the compressed air generating device (2); and at least one temperature sensor (73, 73 ', 73' '), which is connected to the control and regulator (28) via a data or sensor line (59). In order to determine the regenerated compressed air volume of the drying medium (41), which must be conducted through the air dryer (40) for regeneration, it is provided that the cooling medium temperature is measured, the temperature sensor is arranged in front of the cooling medium inlet or behind the cooling medium outlet of the air cooler (22) of the last air cooler arranged in front of the air dryer in the compressed air flow direction. The invention also relates to a method for operating such a compressed air generating system.

Description

Technical Field

[0001] The invention relates to a compressed air generating device, which has: a control and regulator; an electric motor that can be controlled and regulated by the control and regulator; at least one air compressor that can be driven by the electric motor; an air inlet end, via which ambient air can be sucked into the at least one air compressor; at least one air cooler, which is connected to the output end of the at least one air compressor; at least one air dryer, which is connected to the output end of the at least one air cooler; a cooling medium inlet opening, via which a liquid cooling medium can be supplied to at least one air cooler and other components of the compressed air generating device; a cooling medium outlet opening, via which the heated cooling medium can be discharged from the compressed air generating device; and at least one temperature sensor, which is connected to the control and regulator via a data line or a sensor line. The invention also relates to a method for operating such a compressed air generating device. Background Art

[0002] Electrically driven compressors for generating compressed air in vehicles are already known in various embodiments and are described, for example, in DE 10 2018 139 058 A1, DE 10 2013 003 513 A1 and EP 3 516 218 B1. EP 3 331 738 B1 discloses a compressed air generating device for vehicles, which has a piston compressor and two compression stages. The cylinder chambers of the two compression stages are connected to each other via a connecting line, through which the compressed air generated in the first compression stage can be supplied to the second compression stage. During operation of the piston compressor, the ambient air pressure is increased in the first compression stage by means of the back pressure built up in the connected connecting line. An intercooler is arranged in the connecting line between the two compression stages, which is used to cool the air heated during compression in the first compression stage. Here, the pressure of the compressed air in the connecting line is reduced. Therefore, the efficiency of the second compression stage can be increased by the intercooler. Furthermore, further devices for conditioning the air used, such as further cooling devices or air drying devices, can be arranged before or after the first compression stage. It is particularly disadvantageous that the compressor is designed as a reciprocating compressor, which disadvantageously requires lubricants. Furthermore, the design of the cooling system is not described in detail.

[0003] Furthermore, DE 10 2004 051 435 B3 discloses a device for producing dry compressed air, which device has a cooling compressor for sucking in and compressing ambient air. A cooler is arranged downstream of the compressor in the direction of flow of the compressed air, which cooler is used to cool the compressed air produced. The cooling effect of the cooler is achieved by means of a fan and water droplets directed onto the surface of the cooler, where the water droplets evaporate and then draw heat from the cooler and indirectly also from the compressed air. An air dryer is arranged downstream of the cooler, which contains a drying medium, which draws air humidity from the compressed air and thereby reduces the dew point of the compressed air. The compressed air dried in this way has an air humidity of less than 35% at the output of the air dryer, which is sufficient to protect the equipment subsequently supplied with this compressed air from corrosion or freezing due to the formation of water ice.

[0004] Furthermore, DE 44 45 972 C2 discloses a compressor system for producing dry compressed air, in which an air-cooled radiator is used to cool the compressed air produced by the compressor. A water separator is arranged downstream of the radiator, by means of which water droplets formed in the compressed air by condensation when the compressed air is cooled can be removed from the compressed air. Since the compressed air is not dry enough to avoid freezing at low temperatures when it is used in a pressurized medium consumer, an air dryer is arranged downstream of the water separator in which the compressed air is further dried.

[0005] In addition, a compressed air generating device is known from DE 10 2021 121 424.6, which has not yet been published by the applicant, which has an electric motor that can drive two air compressors arranged in series. During the operation of the compressed air generating device, ambient air is sucked and compressed by means of a first air compressor. The pre-compressed compressed air is directed from there 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 transferred to the compressed air consumer via an aftercooler or another switching valve. The intercooler and the aftercooler are cooled by means of a liquid cooling medium and are used to cool the compressed air generated by the air compressor. For example, the liquid cooling medium comes from the cooling circuit of the vehicle and is first supplied to the cooling device of the electric motor in the compressed air generating device, then to the intercooler, and then finally to the cooling device of the first air compressor. From there, the cooling medium enters the aftercooler and then enters the cooling device of the second air compressor, and then the cooling medium returns to the cooling circuit of the vehicle. In this compressed air generating device, an air dryer is neither shown nor described.

[0006] Furthermore, US 2010 / 0303658 A1 discloses a water-cooled and oil-cooled two-stage air compressor, which has a water-cooled intercooler, which is arranged between a first air compressor and a second air compressor in terms of air conduction. The air compressed by the first air compressor is cooled by the intercooler, while the air compressed by the second air compressor is cooled by an aftercooler, and the cooling water inlet of the aftercooler is hydraulically connected to the cooling water outlet of the intercooler.

[0007] Finally, DE 11 2015 006 955 T5 discloses a compressed air supply system for a locomotive and a method for operating the same, wherein the air sucked in and compressed by the compressor is cooled in an air cooler and then delivered to a first compressed air reservoir. From the first compressed air reservoir, the compressed air enters a pre-filter via a check valve closed in the return direction, the pre-filter having a dehydration valve. After liquid and aerosolized water are separated from the compressed air in the pre-filter, the compressed air enters an air dryer. A temperature sensor arranged at or directly next to the air flow inlet end of the air dryer is connected to a controller via a sensor line. The temperature sensor can measure the actual temperature of the compressed air flowing into the air dryer and provide the measured value to the controller. The controller can calculate a suitable flushing cycle time for the dehydration valve based on the saturated partial pressure of water vapor at the measured actual temperature of the compressed air, and control the manipulation of the dehydration valve to remove the water accumulated in the pre-filter.

[0008] The drying medium of the air dryers of these compressed air generating devices must also be constantly cleaned of the moisture accumulated there, since the drying medium can no longer function properly when its moisture absorption capacity reaches saturation. In order to clean the air dryer of this moisture, it is known that during a so-called regeneration process, the dry compressed air generated by the compressed air generating device and stored in the compressed air reservoir is guided back through the air dryer. In this process, the dry compressed air absorbs moisture from the drying medium in the air dryer and transports this moisture outward to the surroundings of the compressed air generating device. Since these regeneration processes consume dry compressed air, which is actually required in motor vehicles, for example, for actuating brake actuators and / or air spring bellows, additional operating time of the compressor is required in order to also store enough compressed air for the regeneration process. However, this is associated with additional energy consumption, which, for example, increases the operating costs of the motor vehicle and, since electrical energy is generated for the electric motor, environmentally harmful CO2 is ultimately released into the atmosphere. Summary of the invention

[0009] Against this background, the object of the present invention is to provide a compressed air generating device having a compressor, a liquid cooling system and an air dryer, which reduces the consumption of dry compressed air for regenerating the drying medium of the air dryer compared to conventional compressed air generating devices of the same type. Furthermore, it is intended to be possible to determine the approximate volume of regeneration compressed air required for each regeneration of the drying medium. Furthermore, a method for operating such a compressed air generating device is intended to be provided.

[0010] The object is achieved with a compressed air generating device having the features of claim 1. The independent method claim defines a method for operating such a compressed air generating device. Advantageous embodiments and improvements are mentioned in the respectively associated dependent claims.

[0011] Therefore, the present invention first relates to a compressed air generating device, which comprises: a control and regulator; an electric motor that can be controlled and regulated by the control and regulator; at least one air compressor that can be driven by the electric motor; an air inlet end, via which ambient air can be sucked into the at least one air compressor; at least one air cooler, which is connected to the output end of the at least one air compressor; at least one air dryer, which is connected to the output end of the at least one air cooler; a cooling medium inlet opening, via which liquid cooling medium can be delivered to at least one air cooler and other components of the compressed air generating device; a cooling medium discharge opening, via which the heated cooling medium can be discharged from the compressed air generating device; and at least one temperature sensor, which is connected to the control and regulator via a data line or a sensor line.

[0012] In order to achieve the task associated with the device, it is also provided in the compressed air generating device that, in order to measure the cooling medium temperature, a temperature sensor is arranged before the cooling medium inlet or after the cooling medium outlet of the air cooler which is the last air cooler arranged before the air dryer in the compressed air flow direction.

[0013] The first recognition of the present invention is that after leaving the last air cooler and before reaching the air dryer, the compressed air carries with it a certain amount of water as air humidity, depending on its temperature. Therefore, if the temperature of the compressed air after leaving the last air cooler and before reaching the air dryer is known, it is possible to calculate how much water the compressed air carries with it as air humidity. If the volume flow of the compressed air in the previous compressed air generation operation and the absorption capacity of the drying medium in the air dryer are also known, it is possible to calculate how large the regeneration compressed air volume must be in order to dry the drying medium with dry regeneration compressed air in the regeneration operation during the operational pauses of the compressed air generation.

[0014] In order to indirectly measure the temperature of the compressed air, it is provided according to the invention that a temperature sensor is arranged upstream of the coolant inlet opening of the compressed air generating device for measuring the temperature of the coolant. This allows the measured value of the temperature sensor located outside the installation space of the compressed air generating device to be used. If the liquid cooling system of such a compressed air generating device uses a temperature sensor of the vehicle cooling system which is already present in the vehicle anyway, it is not necessary to arrange an additional temperature sensor for the compressed air generating device in a space-saving and cost-effective manner.

[0015] However, if the temperature sensor is integrated in the installation space of the compressed air generating system, it can be provided that it is arranged immediately before the coolant inlet of the air cooler which is arranged as the last air cooler before the air dryer in the compressed air flow direction.

[0016] Alternatively or additionally, it can be provided that, in order to measure the cooling medium temperature, the temperature sensor is arranged as the next following component after the cooling medium output of the air cooler which is arranged as the last air cooler before the air dryer in the compressed air flow direction. By comparing the cooling medium temperatures before and after the last air cooler, it can be determined how much heat is extracted from the compressed air flow at the air cooler. This knowledge can be used to adjust the cooling medium pump in terms of its pumping power.

[0017] The second finding is that if the compressed air is particularly cold when it enters the air dryer, it carries less water in the form of air humidity. Therefore, if the compressed air is cooled as much as possible before entering the air dryer, relatively less water will be introduced into the drying medium of the air dryer. As a direct result, the volume of regeneration compressed air required to dry the drying medium of the air dryer during the regeneration operation in the pause of the compressed air production operation will be relatively small.

[0018] In order to utilize this knowledge, the present invention further provides that the air cooler arranged as the last air cooler before the air dryer in the flow direction of the compressed air is arranged so that the coolant can flow through it first as viewed in the flow direction of the coolant.

[0019] It is very important to know the temperature of the compressed air after leaving the air cooler, which is arranged as the last air cooler before the air dryer in the compressed air flow. As already mentioned above, the indirect determination of the compressed air temperature at the mentioned location proposed here is simpler and more cost-effective than measuring the compressed air temperature in the compressed air flow between the above-mentioned air cooler and the air dryer.

[0020] According to another special scheme of the compressed air generating device, the compressed air generating device can have the following items: an electric motor; two air compressors that can be driven by the electric motor and act in sequence; an air inlet end, through which ambient air can be sucked in by means of the first air compressor; two air coolers for cooling the compressed air, which are constructed and arranged as intercoolers or aftercoolers, wherein the input end of the intercooler is pneumatically connected to the output end of the first air compressor, wherein the output end of the intercooler is pneumatically connected to the input end of the second air compressor, wherein the output end of the second air compressor is pneumatically connected to the input end of the aftercooler, and wherein the output end of the aftercooler is pneumatically connected to the input end of the air dryer; and a cooling medium inlet opening, through which liquid cooling medium can be delivered to the intercooler and the aftercooler; and a cooling medium discharge opening, through which the heated cooling medium can be discharged.

[0021] According to the invention, in this compressed air generating device, the aftercooler is arranged so that the cooling medium can flow through it first when viewed from the flow direction of the cooling medium, and there is at least one temperature sensor, which is arranged before or after the aftercooler along the flow direction to measure the temperature of the cooling medium.

[0022] In this compressed air generating device, the above two findings have been taken into consideration as design guidelines, that is, firstly, to measure the temperature of the cooling medium, the temperature sensor is arranged before or after the air cooler (here, the aftercooler) that is arranged as the last air cooler before the air dryer along the compressed air flow. In addition, in this compressed air generating device, it is also provided that the liquid cooling medium first reaches the aftercooler mentioned above, and there, the compressed air is cooled as much as possible before it reaches the air dryer to the extent allowed by the cooling system.

[0023] Therefore, in contrast to the previously known structural forms, the still relatively cold liquid cooling medium is first allowed to flow through an aftercooler, which is arranged immediately before the air dryer in terms of the compressed air flow direction. This allows the compressed air to be cooled to the greatest extent possible, so that the air humidity contained in the compressed air is partially precipitated in the form of small water droplets before reaching the air dryer. These water droplets are then removed from the compressed air before reaching the air dryer, for example, by a water separator in the aftercooler. A small amount of condensed water droplets are brought to the air dryer by the relatively greatly cooled compressed air via a shorter compressed air line, where they are accumulated in a collection area on the input side of the air dryer and removed together with the regenerated compressed air flowing out of the air dryer during the next regeneration process. If there is no water separator, all water droplets condensed before the air dryer are brought to the collection area on the input side of the air dryer. Since relatively more moisture has been removed from the compressed air before reaching the drying medium of the air dryer, the air dryer subsequently needs to dry less compressed air. As a result, regeneration processes which consume dry compressed air do not need to be carried out as frequently on the air dryer, or a smaller amount of compressed air is required per regeneration process, which conserves the reserve amount of stored dry compressed air.

[0024] According to an improved scheme of the compressed air generating device, an electric motor, an inverter that influences the operation of the electric motor, two air compressors, an intercooler, an aftercooler, an air dryer, a multi-circuit protection valve that pneumatically connects the output end of the air dryer to at least one external compressed air reservoir and an external compressed air consumer, and a silencer are arranged to work in a coordinated manner but are separated from each other.

[0025] Alternatively, it can be provided that the electric motor, an inverter that influences the operation of the electric motor, two air compressors, an intercooler, an aftercooler, an air dryer, a multi-circuit protection valve that pneumatically connects the output of the air dryer to at least one external compressed air reservoir and an external compressed air consumer, and a silencer are arranged in or on a common housing.

[0026] In both of the described constructional variants, the mentioned device components are connected to one another in a suitable manner via the described electrical, pneumatic and hydraulic connecting lines which are arranged in the housing, if necessary. This allows the compressed air generating device to be constructed extremely compactly, to be easy to assemble during its manufacture and to be easily fastened to a motor vehicle, for example a commercial vehicle.

[0027] In this regard, it can also be provided that a control and regulator is additionally arranged separately in or on the housing of the compressed air generating device, the control and regulator is connected to the inverter via a first control line for controlling the electric motor, the control and regulator is connected to a two-position three-way solenoid switching valve via a second control line, the two-position three-way solenoid switching valve is used to open or close a regeneration line that pneumatically connects the compressed air reservoir and the air dryer at least indirectly, and the control and regulator is connected to the multi-circuit protection valve via a sensor line.

[0028] By additionally integrating the control and regulator, the two-position three-way solenoid switching valve, and the associated control lines and regeneration lines into the housing of the compressed air generating device, the housing contains other components associated with the compressed air generating device, and these other components make the entire system easier to operate and easier to connect to the motor vehicle. Therefore, when one of these components fails, the compressed air generating device can be easily removed from the commercial vehicle as a whole and sent to a repair shop, and a new compressed air generating device can be quickly and conveniently assembled on the motor vehicle. Since the compressed air generating device is an indispensable device for the operation of commercial vehicles, the method described above avoids long-term maintenance and allows the commercial vehicle to be quickly put into use.

[0029] In order to further improve the maintainability of the compressed air generating device and to enable rapid maintenance, according to another improvement scheme of the compressed air generating device, it can be provided that the compressed air generating device is constructed of four modules, which are arranged in a common housing or on a housing together with the subordinate pneumatic, hydraulic and electrical circuits. Here, the electric motor, inverter, two air compressors and control and regulator are arranged in the compressor module. The compressed air cooling module has an intercooler and an aftercooler, and the air dryer and the multi-circuit protection valve are arranged in the dryer module. In addition, the silencer module includes a silencer, wherein the silencer includes a silencer material. The silencer material is configured so that it also absorbs the water droplets separated from the air dryer and can be guided to the water delivery end of the silencer module like the splashing water injected into the silencer. In addition, at least one regeneration air delivery opening is also configured in the silencer module, which is used to guide the regeneration compressed air to the surrounding environment. In certain application cases, the integration of the silencer module can be cancelled.

[0030] The compressed air generating device having the features of the present invention can be constructed in detail in the following manner in terms of design structure, that is, the output end of the air dryer is connected via a first check valve closed in the direction of the air dryer with the help of a fifth compressed air line; the fifth compressed air line leads to at least one compressed air reservoir and to a compressed air consumer via the multi-circuit protection valve; the regeneration compressed air input end of the air dryer is connected to the output end of the two-position three-way solenoid switching valve via a second check valve opened in the direction of the regeneration compressed air input end, a throttle and a first line branch; the input end of the two-position three-way solenoid switching valve is connected to the fifth compressed air line via the regeneration compressed air line; when the two-position three-way solenoid switching valve is operated, dry compressed air can be supplied to the air dryer as regeneration compressed air via the two-position three-way solenoid switching valve, the first line branch, the throttle and the first check valve; and also when the two-position three-way solenoid switching valve is operated, the regeneration compressed air can be supplied to the pneumatic control input end of the two-position two-way switching valve, which is assigned to the regeneration air output end of the air dryer.

[0031] The regeneration process at the air dryer is therefore initiated by the control and regulator and is controlled critically by means of a 2 / 3-way solenoid switching valve. With the 2 / 3-way solenoid switching valve, not only is the dry regeneration compressed air directed to the air dryer, but also the control pressure is simultaneously directed to the control pressure input of the pneumatic 2 / 2-way switching valve for opening the regeneration air output of the air dryer. The control pressure is generated from a small portion of the regeneration compressed air from the compressed air reservoir that is also directed to the air dryer for drying the drying medium there.

[0032] Another improvement is that a pressure-controlled two-way switching valve is also assigned to the collection area of ​​the air dryer, and the pneumatic control input of the pressure-controlled two-way switching valve is connected to the output of the two-way three-way electromagnetic switching valve via a second line branch. The two-way switching valve is configured so that it is closed when not operated. In addition, the two-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 supplied via the second line branch. When the two-way switching valve is open, the dry regeneration compressed air can be guided through the drying medium of the air dryer in the regeneration compressed air flow. After flowing through the drying medium, the regeneration compressed air can be guided to the collection area of ​​the air dryer, where it can entrain the accumulated condensate, and can be removed from the air dryer via at least one regeneration air outlet on the air dryer.

[0033] Furthermore, it can be provided that, instead of the two-position three-way solenoid switching valve, there are two two-position two-way solenoid switching valves which can be controlled by a control and regulator, wherein a first two-position two-way solenoid switching valve is arranged in a first line branch before the throttle element in the flow direction of the regenerating compressed air, wherein a second two-position two-way solenoid switching valve is arranged in a second line branch before the pressure-controlled two-position two-way switching valve, and wherein the fifth compressed air line is directly connected to the first line branch and directly connected to the second line branch before the two two-position two-way solenoid switching valves in the flow direction of the regenerating compressed air.

[0034] Furthermore, according to another advantageous development, the compressed air generating device has an ambient temperature sensor, with which the ambient temperature can be measured. The ambient temperature sensor is also connected to the control and regulator via a data or sensor line. It is advantageous to know and take into account the ambient air temperature, because the water content of the ambient air that can be sucked in by the compressed air generating device is dependent on the air temperature. At low air temperatures, its water content may be less than at high temperatures. Furthermore, it must be taken into account that the ambient air temperature influences the temperature of the compressed air reservoir from which the regeneration compressed air volume is extracted during the regeneration operation and the temperature of the compressed air stored therein. As a result, the ambient temperature also influences the moisture absorption capacity of the regeneration compressed air when it flows through the drying medium of the air dryer.

[0035] The data or sensor lines mentioned here may be lines of a CAN bus.

[0036] The invention also relates to a method for operating a compressed air generating device having at least one of the features of the device claim and the above device description. According to the method, air compressed by means of at least one air compressor is cooled in at least one air cooler. The cooled compressed air is subsequently fed to an air dryer and dried there in order to then be conducted to a compressed air consumer and / or to at least one compressed air reservoir. During the regeneration operation of the compressed air generating device, in order to regenerate the drying medium arranged in the air dryer, a certain amount of dry compressed air of the regeneration compressed air volume required for this purpose is conducted through the drying medium and subsequently discharged to the surrounding environment.

[0037] It is provided here that the volume of regeneration compressed air required for regenerating the drying medium is calculated at least as a function of the temperature of the cooling medium before and / or after the air cooler through which it flows, that is, the last air cooler arranged before the air dryer, and that the dry compressed air of the regeneration compressed air volume determined in this way is subsequently guided through the air dryer.

[0038] Since the amount of water that the compressed air carries with it as air humidity on its way to the air dryer after passing through the last air cooler is related to the compressed air temperature there, it would seem disadvantageous not to initially determine the volume of regeneration compressed air required for the regeneration operation of the compressed air generating device based on a direct measurement of the temperature of the compressed air flow before the air dryer.

[0039] However, the approach presented here has the advantage that no additional temperature sensors are required to obtain conclusions about the temperature of the compressed air before it reaches the air dryer and how much water it carries in the form of air humidity. As stated above, today, in every motor vehicle with a liquid cooling system, the temperature of the cooling medium is measured by means of a temperature sensor after leaving the cooler of the liquid cooling system, and the measured value of the cooling medium temperature is used for various purposes in the motor vehicle, for example via a CAN data bus. Knowing the temperature of the cooling medium immediately after leaving the vehicle cooler or the temperature immediately before the air cooler in question, it is possible to indirectly infer the temperature of the compressed air after leaving the air cooler, without requiring a special temperature sensor for this purpose.

[0040] The operation of the compressed air generating system and in particular the supply of the cooling medium can then be regulated in such a way that the cooling effect of the last air cooler before the air dryer is maximized. As a result, the compressed air is also cooled to the maximum before the air dryer, so that the compressed air has only a relatively small amount of moisture that is taken on by the air dryer. As a result, the drying medium of the air dryer does not need to be regenerated as frequently and with a smaller volume of regeneration compressed air.

[0041] In a further embodiment of the method, it is provided that the cooling medium temperature before the cooling medium inlet opening of the compressed air generating device is measured by means of a first temperature sensor, and that the regeneration compressed air volume required for drying the drying medium in the air dryer is guided through the air dryer in a controlled and / or regulated manner depending on the measured cooling medium temperature.

[0042] Alternatively to this, it can be provided that the cooling medium temperature upstream of the cooling medium inlet of an air cooler immediately upstream of the last air cooler arranged in the compressed air flow direction before the air dryer is measured with the aid of a second temperature sensor, and that the regeneration compressed air volume required for drying the drying medium in the air dryer is directed through the air dryer in a controlled and / or regulated manner depending on the measured cooling medium temperature.

[0043] Furthermore, it can also be provided that the cooling medium temperature after the cooling medium output of the air cooler which is the last air cooler arranged before the air dryer in the compressed air flow direction is measured by means of a third temperature sensor, and that the regeneration compressed air volume required for drying the drying medium in the air dryer is directed through the air dryer in a controlled and / or regulated manner depending on the measured cooling medium temperature.

[0044] Another possible solution for determining the optimum regeneration compressed air volume sufficient for drying the drying medium in the air dryer is to measure the temperature of an inverter which is present for controlling and regulating the electric motor, to use the measured inverter temperature to calculate the cooling medium temperature in the air cooler which is arranged as the last air cooler before the air dryer in the compressed air flow direction, and to direct the regeneration compressed air volume required for drying the drying medium in the air dryer through the air dryer in a controlled and / or regulated manner depending on the cooling medium temperature determined in this way.

[0045] The temperature of the electronics of the inverter can be used as the temperature of the inverter. In this method variant, the arrangement of temperature sensors in the region of the coolant lines and / or the mentioned air cooler can be omitted in a cost-saving manner.

[0046] According to a further specialization of the method, the following method steps can be provided: a) sucking in ambient air by means of a first air compressor, b) pre-compressing the sucked ambient air to a first air pressure value in a first air compressor, c) Cooling the intercooler with liquid cooling medium, d) cooling the pre-compressed compressed air in an intercooler, e) further compressing the compressed air to a second higher pressure value by means of a second air compressor, f) cooling the aftercooler with a liquid cooling medium, wherein the aftercooler, viewed in the flow direction of the cooling medium, is the first air cooler to be hydraulically reached by the cooling medium, g) cooling the compressed air further compressed in the second air compressor in an aftercooler, h) Drying the cooled compressed air in an air dryer, i) forwarding the cooled and dried compressed air to a compressed air consumer and / or to at least one compressed air reservoir.

[0047] These method steps clearly show that the compressed air leaving the second air compressor is cooled to the extent that a freshly supplied liquid cooling medium can achieve when flowing through the aftercooler. For this purpose, it is provided that the liquid cooling medium is not first guided to a cooling device or an intercooler of the electric motor, as in the compressed air generation device according to DE 10 2039 139 424.6, in order to cool these cooling devices during operation. On the contrary, in the compressed air generation device presented here, the cooling medium is first guided to the aftercooler in order to cool the cooling medium and thus also cool the compressed air as much as possible. It is thus possible according to the method to cool the generated compressed air to a great extent before it reaches the air dryer, so that as much moisture as possible is separated from the compressed air and guided out.

[0048] In order to also cool further components of the compressed air generating system with a liquid cooling medium, the following further method steps are provided in addition to the method mentioned: j) Transfer the liquid cooling medium from the aftercooler to the intercooler, k) Transferring the liquid cooling medium from the intercooler to the cooling device of the electric motor, l) transferring the liquid cooling medium from the cooling device of the electric motor to the cooling device of the second air compressor, m) transferring the liquid cooling medium from the cooling device of the second air compressor to the cooling device of the inverter, n) transferring the liquid cooling medium from the cooling device of the inverter to the cooling device of the first air compressor, o) Transferring the liquid cooling medium from the cooling device of the first air compressor to the external cooling device.

[0049] In addition to the way in which the cooling medium is conducted (especially initially to the aftercooler) and the way in which the compressed air is conducted in the compressed air generation system, the way in which the drying medium of the air dryer is regenerated is also particularly important. In this regeneration, the temporarily stored dry compressed air is caused to flow in the opposite direction through the drying medium, which has removed moisture from the compressed air supplied during the previous drying process and whose dryness has now been greatly reduced. In this process, the compressed air will take up moisture from the drying medium and flow out of the air dryer with it into the surroundings. The frequency with which such regeneration processes need to be carried out and the compressed air volume required for these regeneration processes influence the demand for compressed air to be generated by the compressed air generation system during vehicle operation. Since water has already been separated from the compressed air in the aftercooler when the compressed air is cooled as described above, this water enters the inlet region of the air dryer in the form of a water film or water droplets together with the compressed air conducted to the air dryer, from which this water is discharged into the surroundings.

[0050] However, it can also be conveniently provided that the time interval between two regeneration operations for drying the drying medium of the air dryer is controlled and / or regulated as a function of the temperature of the cooling medium at the outlet of the external cooling device or at the inlet of the aftercooler.

[0051] Since the temperature of the cooling medium plays a decisive role in how much water has condensed at the aftercooler from the compressed air supplied to the aftercooler, a relatively low cooling medium temperature will result in relatively more water being separated from the compressed air at the aftercooler and discharged therefrom. As a result, the drying medium of the air dryer is less stressed than in the case of a relatively high cooling medium temperature, so that the regeneration compressed air volume can be smaller or, for example, the time interval between two regeneration processes can be longer.

[0052] When performing a regeneration process of the type described, the vehicle's ambient temperature must also be taken into account, since the compressed air stored in the compressed air reservoir will, after a period of time, take on the ambient temperature via the walls of the compressed air reservoir. Since the compressed air stored in this compressed air reservoir is also used to regenerate the drying medium in the air dryer, and the compressed air temperature also determines the water storage capacity of the regeneration compressed air, knowing the ambient temperature is important for determining the necessary regeneration compressed air volume.

[0053] Therefore, when conducting previously dried and temporarily stored compressed air as regeneration compressed air in the opposite direction through the air dryer for regenerating the drying medium in the air dryer, it can be provided that the regeneration compressed air volume required for drying the drying medium is controlled and / or regulated in dependence on the average ambient temperature.

[0054] In the method, it can also be provided that the time interval between two regeneration processes for drying the drying medium 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 within a predetermined period of time.

[0055] For example, if the ambient temperature and the coolant temperature change rapidly 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 drying medium or the duration and / or frequency of the regeneration process respectively is controlled and regulated depending on the difference between the ambient temperature and the coolant temperature.

[0056] In the case of unregulated control of the regeneration of the drying medium of the air dryer, according to a further improvement of the described method for operating a compressed air generating device, it is provided that a maximum temperature value of the cooling medium to be expected during operation of the compressed air generating device is determined, this value of the cooling medium temperature is used as the basis for determining the maximum regeneration compressed air volume, and the associated regeneration process for the drying medium is carried out using this maximum regeneration compressed air volume. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] For a better understanding of the invention, this specification is accompanied by a drawing which shows a compressed air generating device having the features of the invention as a single figure. In this schematic diagram, the pneumatic lines for guiding air or compressed air are represented by solid lines. The hydraulic lines for transporting liquid cooling medium are represented by short dashed lines, while the electrical lines are represented by dotted lines. DETAILED DESCRIPTION

[0058] In the embodiment shown here, the compressed air generating device 2 has a closed but also openable housing 6, in which the individual components of the compressed air generating device 2 are modularly combined, and these modules are arranged one after another. Therefore, the compressor 4 is arranged in a compressor module 90, which has an electric motor 24 with two drive shafts 30, 32, an inverter 26, a first air compressor 16, a second air compressor 18 and a control and regulator 28. Arranged in the housing 6 after the compressor module is a compressed air cooling module 92, which has an intercooler 20 and an aftercooler 22. The two air coolers 20, 22 are used to cool the compressed air generated by the compressor 4. For this purpose, the two air coolers 20, 22 use a liquid cooling medium delivered by an external cooling device 82. In the selected example, the external cooling device 82 is a cooling device of a commercial vehicle with a suitable (not shown here) heat exchanger. The amount of liquid coolant which is conducted per second through coolable components of the compressed air generating device 2 can be adjusted by means of a controllable coolant pump which is connected to the control and regulator 28 in a controllable manner.

[0059] Next, there is a dryer module 94 in the housing 6, in which the air dryer 40 and the advantageous multi-circuit protection valve 50 are arranged in the example shown. The air dryer 40 contains a drying medium 41, with which the air humidity can be extracted from the compressed air guided to the air dryer 40. When the dried compressed air is guided through the air dryer 40 in the opposite direction during the regeneration process, the drying medium 41 can release this moisture to the dried air again. The multi-circuit protection valve 50 does not have to be a component of the dryer module 94, but it is advantageous to arrange it in the common housing 6. What can be achieved by means of the multi-circuit protection valve 50 is that the compressed air released from the air dryer 40 can be selectively released to different compressed air consumers 51, 52 and / or compressed air storage 45. In addition, it should be mentioned that the sixth compressed air line DL6 and the seventh compressed air line DL7 leading to the compressed air consumers 51, 52 can also be connected to other compressed air storages halfway. Likewise, at least one further compressed air consumer (not shown) is connected to the compressed air reservoir 45 shown.

[0060] Finally, the compressed air generating device 2 has a silencer module 96, which is constructed as a silencer 43 containing a silencer material 44. The silencer material 44 can suppress the noise emission generated when the compressed air loaded with moisture is discharged from the air dryer 40 during the regeneration process. For this purpose, the silencer module 96 has a plurality of regeneration air outlet openings, only one of which is shown, through which the exhaust gas AL can be released into the surrounding environment. In addition, the silencer module 96 or the silencer 43 has at least one water outlet opening 36 at its lowest part, and the water droplets separated from the compressed air in the air dryer 40 during normal operation and / or the splashing water that penetrates through the regeneration air outlet opening 34 can be removed through the water outlet opening via the water separation path 80 formed by itself. The silencer module 96 or at least its silencer 43 can be fastened in or on the housing 6 in a way that can be easily replaced.

[0061] The components of the four modules 90 , 92 , 94 , 96 are connected as required via pneumatic, hydraulic and electrical lines, which will be discussed in detail when describing the method for operating the compressed air generating system 2 .

[0062] The function and interaction of the components of the compressed air generating device 2 are as follows:

[0063] The operation of the compressor 4 is controlled and regulated by means of the control and regulator 28 already described. The control and regulator 28 is connected via a low-voltage line 57 to a low-voltage source (not shown in detail), 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 a sensor arranged on the inverter 26, such as a temperature sensor (not shown). The sensor is also supplied with 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 a voltage source (not shown in detail).

[0064] In order to start and operate the electric motor 24 of the compressor 4, the electric motor is driven in a desired manner by means of a controller and regulator 28 and an inverter 26. As a result, the two drive shafts 30, 32 of the electric motor 24 are caused to rotate. The first drive shaft 30 is connected to the first air compressor 16 in a driving manner, and the second drive shaft 32 is connected to the second air compressor 18 in a driving manner. The two air compressors 16, 18 are scroll compressors known per se. The first air compressor 16 is connected to the ambient air L on the input side via the air inlet opening 8 in the housing 6. When the first air compressor 16 is in operation, the first air compressor sucks in the ambient air L and compresses the ambient air into compressed air with a first air pressure value.

[0065] The first air compressor 16 is pneumatically connected to the input of the second air compressor 18 on the output side via the first compressed air line DL1, the intercooler 20 and then via the second compressed air line DL2. The intercooler 20 cools the pre-pressed compressed air, wherein water is condensed and discharged if necessary. In the second air compressor 18, the cooled compressed air is then further compressed to the desired higher second air pressure value and then supplied to the already mentioned aftercooler 22 via the third compressed air line DL3. The compressed air is further cooled in the aftercooler 22. Here, water condenses from the compressed air.

[0066] The compressed air after cooling and still with residual moisture enters the collection area 49 on the input side of the air dryer 40 from the output of the aftercooler 22 via the fourth compressed air line DL4. The condensed water also enters the collection area 49 of the air dryer 40 in the form of entrained droplets or as a water film. In the subsequent regeneration process, the water is separated from the air dryer 40 via the regeneration air output 42 of the air dryer 40. As a result, the condensed water does not enter the drying medium 41 of the air dryer 40, which is also schematically illustrated by the single drawing with droplets. The compressed air from the short fourth compressed air line DL4, which is partially dehydrated in this way and still with residual moisture, enters the drying medium 41 of the air dryer 40, flows through the drying medium 41 in the drying air flow 23 and is dried there. The drying medium 41 can absorb the air humidity in the compressed air provided and release it again to the dry air in the subsequent regeneration process.

[0067] The dried compressed air then leaves the air dryer 40 via a first spring-loaded nonreturn valve 29 which is closed in the direction of the air dryer 40 and then enters the fifth compressed air line DL5. The fifth compressed air line DL5 leads to a multi-circuit protection valve 50 which is at least indirectly controlled by the control and regulator 28. For this purpose, the multi-circuit protection valve 50 is connected to the control and regulator 28 via a sensor line 56. Via the multi-circuit protection valve 50, the dried compressed air can be guided, for example, via the already described sixth compressed air line DL6 and the compressed air outlet opening 10 in the housing 6 to the first compressed air consumer 51 and via the described seventh compressed air line DL7 to the second compressed air consumer 52. The multi-circuit protection valve 50 can guide the dried compressed air via the eighth compressed air line DL8 to at least one compressed air reservoir 45. As required, compressed air can also be supplied to other compressed air consumers and / or compressed air reservoirs (not shown) via the compressed air reservoir 45. As required, the compressed air stored in the compressed air storage 45 may also be delivered to other compressed air consumers via the multi-circuit protection valve 50 , or returned to the fifth compressed air line DL5 for regenerating the drying medium 41 of the air dryer 40 .

[0068] If a predetermined air pressure is set in the compressed air consumers 51, 52 and in at least one compressed air reservoir 45 and the electric motor 24 of the compressor module 90 is turned off, the drying medium 41 arranged in the air dryer 40 and saturated with water can be regenerated, that is, the water stored there can be removed. For this purpose, the compressed air generating device 2 has a regeneration line DL5a. The regeneration line DL5a is connected to at least the eighth compressed air line DL8 leading to the compressed air reservoir 45 via the fifth compressed air line DL5, and is connected to the air dryer 40. A two-position three-way electromagnetic switching valve 72 is arranged in the regeneration line DL5a, which can be driven by the control and regulator 28 and is connected to the control and regulator via the control line 55.

[0069] When the two-position three-way solenoid switching valve 72 is not operated, the regeneration line DL5a is closed, so that no compressed air can enter the air dryer 40 from the compressed air reservoir via the multi-circuit protection valve 50. In order to perform the regeneration operation of the air dryer 40, the two-position three-way solenoid switching valve 72 is operated. As a result, the regeneration line DL5a is in an open state. As a result, part of the compressed air in the dried compressed air enters the throttle 75 from the compressed air reservoir 45 through the first branch DL5b of the regeneration line DL5a. There, the dried compressed air expands, thereby increasing the volume of the compressed air. Subsequently, the compressed air passes through the second spring-loaded check valve 76 and then enters the air dryer 40 via the regeneration compressed air inlet 70. Then, as long as the pressure-controlled two-position two-way switching valve 39 at the collection area 49 of the air dryer 40, which acts as an exit valve, is in an open state, the expanded compressed air flows through the air dryer 40 and the drying medium 41 arranged there in the regeneration compressed air flow 77.

[0070] In order to operate the pressure-controlled 2 / 2-way switching valve 39, another part of the dried compressed air is guided to the pressure-controlled 2 / 2-way switching valve 39 through the second line branch DL5c after the output end of the 2 / 2-way electromagnetic switching valve 72. The pressure-controlled 2 / 2-way switching valve 39 is designed so that it closes the connection from the collection area 49 of the air dryer 40 to the regeneration air output end 42 of the air dryer 40 in the non-actuated switching position, and opens the connection in the actuated switching state. Therefore, when the 2 / 2-way electromagnetic switching valve 72 is switched to its open position, the pressure-controlled 2 / 2-way switching valve 39 will also be in the open state.

[0071] According to an alternative embodiment, there are two two-position two-way solenoid switching valves that can be driven by the control and regulator 28 to replace the two-position three-way solenoid switching valve 72. These two two-position two-way solenoid switching valves are not shown in the figure, but their arrangement can be easily understood by those skilled in the art based on the following description. The first two-position two-way solenoid switching valve is arranged in the first line branch DL5b before the throttle 75 along the flow direction of the regeneration compressed air, and the second two-position two-way solenoid switching valve is arranged in the second line branch DL5c before the pressure-controlled two-position two-way solenoid switching valve 39. In addition, here, the fifth compressed air line DL5 is directly connected to the first line branch DL5b and directly connected to the second line branch DL5c before the two two-position two-way solenoid switching valves along the flow direction of the regeneration compressed air.

[0072] As soon as the two 2 / 2-way solenoid switching valves are switched to their open position, the dry regeneration compressed air can be guided through the air dryer 40 into the silencer 43 in order to dry the drying medium 41 while the pressure-controlled 2 / 2-way switching valve 39 is also opened.

[0073] In addition, with the help of this structure, when the first two-position two-way solenoid switching valve is closed, the second two-position two-way solenoid switching valve is opened, and thus the pressure-controlled two-position two-way switching valve 39 is opened, the compressed air supplied to the collection area 49 of the air dryer 40 via the aftercooler 22 can advantageously remove the water W accumulated there.

[0074] When the 2 / 2-way switching valve 39 is opened under pressure control, the expanded compressed air in the regeneration compressed air flow 77 will flow through the drying medium 41 in the direction of the silencer 43. At this time, moisture is extracted from the drying medium 41. Subsequently, the compressed air enriched with moisture in this way and the moisture that has condensed and accumulated in the collecting area 49 of the air dryer 40 will leave the air dryer 40 via the regeneration air outlet 42 of the air dryer and thus enter the silencer 43.

[0075] Then, the moist exhaust gas AL flows through the silencer material 44 arranged in the silencer 43, and flows to the at least one regeneration air outlet opening 34 of the silencer 43 of the compressed air generating device 2 via the exhaust gas path 78. Water droplets that may be formed in the regeneration compressed air flow or in the silencer material 44 of the silencer 43 when the regeneration compressed air flow passes through the silencer 43, as well as condensed water from the collection area 49 of the air dryer 40, flow in the silencer 43 via the water separation path 80 described above toward the at least one water outlet opening 36 of the silencer 43. However, the water outlet opening 36 of the silencer 43 is also used to remove splash water that may penetrate into the silencer 43 via the at least one regeneration air outlet opening 34 again.

[0076] The regeneration process ends when a predetermined, sufficiently large volume of regeneration compressed air has flowed through the drying medium 41 of the air dryer 40 so that it can be used for a further air drying phase.

[0077] The flow path of the liquid cooling medium delivered from the external cooling device 82 is very important for the construction of the compressed air generating device 2 according to the present invention. The cooling medium is cooled to a predetermined temperature in the external cooling device 82 and delivered to the compressed air generating device 2 via the cooling medium delivery line Kin. The cooling activity of the external cooling device 82 is controlled and regulated by the control and regulator 28. In the case where the cooling medium temperature is preferably regulated, the current actual temperature of the cooling medium is measured by the first temperature sensor 73 at the output end of the cooling device 82, and then the cooling medium temperature is regulated to a predetermined target value of the cooling medium temperature. For this purpose, the first temperature sensor 73 is connected to the control and regulator 28 via the data and / or sensor line 59 of the CAN bus.

[0078] The cooling medium enters the compressed air generating device 2 from the external cooling device 82 through the cooling medium inlet opening 12 and enters the compressed air cooling module 92. Subsequently, the cooling medium flows into the aftercooler 22 via the first cooling medium line KL1 in order to cool the compressed air generated by the compressor 4 there as much as possible. Since the cooling medium is first guided into the aftercooler 22, the lowest temperature of the cooling medium within the compressed air generating device 2 can be utilized. As a result, the compressed air is already cooled to a relatively large extent before it is introduced into the air dryer 40, as a result of which part of the entrained air humidity is condensed and at least partially separated in the aftercooler 22. The condensed water is also guided into the collecting area 49 of the air dryer 40 and discharged from there directly or via the silencer 43 to the surrounding environment. Through this process, a large amount of water can be extracted from the compressed air before it reaches the air dryer 40. The lower the temperature of the cooling medium, the more water is extracted.

[0079] Therefore, compared with conventional compressed air generating devices, the drying medium 41 of the air dryer 40 will be dried less frequently during the regeneration process, or such a regeneration process can be performed with a smaller volume of regeneration compressed air than is usually the case. As a result, more of the dried compressed air stored in the compressed air reservoir 45 is provided to the compressed air consumers 51, 52, so that the electric motor 24 of the compressor 4 of the compressed air generating device 2 does not need to be put into operation so frequently. As a result, for example, when such a compressed air generating device 2 is arranged in a vehicle and operated, the consumption of electrical energy is reduced, thereby reducing the exhaust gas release of the vehicle and thus the output of CO2 of the vehicle.

[0080] Therefore, the lower the temperature of the cooling medium at the outlet of the aftercooler 22, the lower the frequency of the regeneration process or the required compressed air volume for regeneration can be. It is therefore advantageous that the adjustment of the actuation frequency and / or the actuation duration of the two-position three-way electromagnetic switching valve 72 by means of the control and regulator 28 is also carried out in dependence on the temperature of the cooling medium. For this purpose, as briefly mentioned above, according to the embodiment shown in the only 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 cooling medium inlet opening 12, by means of which the temperature of the liquid cooling medium can be measured. Usually, such a temperature sensor 73 is already a component of the cooling device 82. The temperature measurement value obtained in this way can be guided to the control and regulator 28 via the mentioned data and / or sensor line 59. Then, the control and regulator 28 controls and regulates the regeneration of the drying medium 41 of the air dryer 40 directly via the actuation frequency and / or actuation duration of the two-position three-way electromagnetic switching valve 72 and indirectly by means of the pressure-controlled two-position two-way switching valve 39, taking into account the current cooling medium temperature.

[0081] As an alternative solution to this, as shown in the single figure, the temperature of the cooling medium can also be measured at the cooling medium input of the aftercooler 22 by means of a second temperature sensor 73' and / or at the cooling medium output of the aftercooler 22 by means of a third temperature sensor 73", which are likewise connected to the control and regulator 28 via a data and / or sensor line 59. The data and / or sensor line 59 connected to the respective temperature sensor 73', 73" can also be arranged completely within the compressed air generating device 2 in a manner different from that shown in the single figure.

[0082] In such regulation, it should also be noted that the temperature of the cooling medium may fluctuate during the operation of the compressed air generating device 2. This may be caused by different load states of the vehicle and its systems and / or by rapidly changing ambient temperatures. In most vehicles, since the current temperature of the cooling medium is measured by means of the first temperature sensor 73 for regulating the mentioned external cooling device 82, the respective current value of the temperature of the cooling medium is provided to the control and regulator 28 via the already mentioned data and / or sensor line 59 of the CAN bus. Based on the current value of the cooling medium temperature, the control and regulator 28 can control and regulate the actuation duration of the two-position three-way electromagnetic switching valve 72 and thus the frequency and duration of the regeneration process of the dryer 40 at any time in a temperature-dependent manner.

[0083] Since most vehicles in traffic today also use an ambient temperature sensor 74 to measure the vehicle's ambient temperature and display it using a display element, the ambient temperature is also provided to the control and regulator 28 via the data and / or sensor line 59 of the CAN bus for controlling and adjusting the actuation duration of the two-position three-way solenoid switching valve 72, and further for controlling and adjusting the frequency and duration of the regeneration process on the air dryer 40.

[0084] The ambient temperature of the vehicle is also very important for the control and regulation of the regeneration process, since the compressed air continues to cool down after it has been dried in the dryer 40 until it reaches the temperature of the compressed air tank 45 or the compressed air consumers 51, 52, which usually have the temperature of the ambient environment. During this further cooling process, the relative humidity in the compressed air rises again. In order not to cause corrosion processes or even condensation of water and ice formation when the ambient temperature in the compressed air reservoir and in the compressed air consumers is lower than the temperature of the coolant, the dryness of the compressed air must ideally also take into account the current ambient temperature.

[0085] This dryness can be adjusted via the volume of regeneration compressed air used during the regeneration process and / or the frequency of regeneration within the time period of interest. For example, if a substantially excessive volume of regeneration compressed air is used during the regeneration process, the drying medium 41 becomes drier than required by the previously known practice. As a result, during the subsequent transport process, the compressed air guided through the air dryer 40 will lose more moisture than previously required, so that the compressed air has a higher dryness when it leaves the air dryer 40. When the compressed air is further cooled in the compressed air container or the compressed air consumer, the dryness of the compressed air is advantageously very high, so that no condensation and possible ice formation occurs there.

[0086] Thus, the regeneration compressed air volume and / or the frequency of the regeneration process are controlled and regulated by means of the control and regulation device 28 when the ambient temperature remains constant as a function of the temperature of the cooling medium, and when the cooling medium temperature remains constant as a function of the ambient temperature. If both the ambient temperature and the cooling medium temperature change, the duration and / or the frequency of the regeneration process will be controlled and regulated as a function of the difference between the two mentioned temperatures.

[0087] If this regulation is omitted, the volume of regeneration compressed air required for each regeneration process must also cover the most unfavorable case, i.e. the maximum temperature of the cooling medium to be expected during operation of the compressed air generating device 2. As a result, such a regeneration process for the drying medium 41 is always carried out using the maximum regeneration compressed air volume known in advance.

[0088] After flowing through the aftercooler 22, the liquid coolant enters the intercooler 20 via the second coolant line KL2, where it cools the compressed air pre-pressed by the first air compressor 16. After cooling the pre-compressed compressed air in the intercooler 20, the liquid coolant is guided to the cooling device 25 of the electric motor 24 via the third coolant line KL3. There, the coolant cools the stator of the electric motor 24, for example.

[0089] Subsequently, the cooling medium flows via the fourth cooling medium line KL4 to the cooling device 48 of the second air compressor 18 of the compressor 4, thereby cooling the second air compressor during its compression activity. Then, the cooling medium flows via the fifth cooling medium line KL5 to the cooling device 27 of the inverter 26 in order to cool the inverter. After that, the cooling medium flows via the sixth cooling medium line KL6 to the cooling device 46 of the first air compressor 16 of the compressor 4 in order to also cool the first air compressor. Finally, the heated cooling medium is guided from the compressor module 90 and the housing 6 of the compressed air generating device 2 via the cooling medium discharge line Kout through the cooling medium delivery opening 14 to the external cooling device 82.

[0090] Studies have shown that a relatively large degree of cooling of the compressed air in the aftercooler 22 has no negative effect on the operation of the compressed air generation device 2. Even further advantages can be seen. This will be explained in conjunction with the following example:

[0091] In this case, the compressed air generating device 2 designed according to the invention is installed in a truck and uses a cooling system for cooling the aforementioned liquid cooling medium, which also cools the internal combustion engine of the truck. When the internal combustion engine is cold started, i.e. when the internal combustion engine is started at very low ambient temperatures, if the temperature of the cooling system of the internal combustion engine quickly rises above the ambient temperature, this is advantageous in terms of the operating characteristics of the vehicle battery, in terms of reducing the exhaust gas emissions of the truck, and in terms of providing warm air by means of interior heating of the truck. Since the electrically operated compressed air generating device 2 is also put into operation at the same time when the internal combustion engine is cold started, in order to generate the compressed air required for operation, the compressed air is cooled as much as possible by the liquid cooling medium. As a result, the waste heat drawn from the compressed air generating device 2, in particular the heat generated by the operation of the electric motor 24, the inverter 26 and the two air compressors 16, 18, is advantageously indirectly used to relieve the load on the vehicle battery via the heated liquid cooling medium. In this case, during the cold start of the truck and during the short warm-up phase, temperatures at which ice can form at the inlet of the aftercooler 22 and the air dryer 40 can also be tolerated. Since the warm-up phase is relatively short, any ice that may form at the inlet of the aftercooler 22 and the air dryer 40 will evaporate during the subsequent normal operating phase and be absorbed as air humidity in the compressed air.

[0092] List of reference numerals (part of the description)

[0093] 2 Compressed air generating equipment

[0094] 4 Compressor

[0095] 6 Housing of compressed air generating equipment

[0096] 8 Air inlet opening

[0097] 10 Compressed air outlet opening

[0098] 12 Cooling medium inlet opening

[0099] 14 Cooling medium outlet opening

[0100] 16 First Air Compressor

[0101] 18 Second air compressor

[0102] 20 Intercooler, air cooler

[0103] 22 Aftercooler, air cooler

[0104] 23 Dry air flow in air dryer

[0105] 24 Electric Motor

[0106] 25 Cooling equipment for electric motors

[0107] 26 Inverter

[0108] 27 Cooling equipment for inverter

[0109] 28 Control and Regulator

[0110] 29 First check valve

[0111] 30 First drive shaft

[0112] 32 Second drive shaft

[0113] 34 Regeneration air outlet opening

[0114] 36 Water outlet opening of the silencer

[0115] 39 2 / 2-way switching valve, outlet valve on air dryer

[0116] 40 Air Dryer

[0117] 41 Drying media in air dryers

[0118] 42 Regeneration air outlet of air dryer

[0119] 43 Silencer

[0120] 44 Sound-absorbing materials

[0121] 45 Compressed air storage tank

[0122] 46 Cooling equipment for the first air compressor

[0123] 48 Cooling equipment for the second air compressor

[0124] 49 Collection area of ​​air dryer for water droplets

[0125] 50 Multi-circuit protection valve

[0126] 51 First compressed air consumer

[0127] 52 Second compressed air consumer

[0128] 54 Sensor lines

[0129] 55 Control line from control and regulator to two-position three-way solenoid switching valve

[0130] 56 Sensor lines from control and regulator to multi-circuit protection valve

[0131] 57 Low voltage line

[0132] 58 High voltage line

[0133] 59 CAN bus data or sensor line

[0134] 70 Regeneration compressed air input for air dryer

[0135] 72 Two-position three-way solenoid switching valve

[0136] 73 First temperature sensor (measuring cooling medium)

[0137] 74 Ambient temperature sensor

[0138] 75 Throttle

[0139] 76 Second check valve

[0140] 77 Regeneration Compressed Air Flow in Air Dryer

[0141] 78 Exhaust gas path in the silencer

[0142] 80 Water separation path in silencer

[0143] 82 External cooling equipment

[0144] 90 Compressor Module

[0145] 92 Compressed air cooling module

[0146] 94 Dryer Module

[0147] 96 Silencer Module

[0148] L Ambient air

[0149] AL Exhaust

[0150] Kin cooling medium delivery line

[0151] Kout Cooling medium discharge line

[0152] W Water

[0153] DL1 First compressed air line

[0154] DL2 Second compressed air line

[0155] DL3 Third compressed air line

[0156] DL4 Fourth compressed air line

[0157] DL5 Fifth compressed air line

[0158] DL5a Regeneration Compressed Air Line

[0159] DL5b First line branch

[0160] DL5c Second line branch

[0161] DL6 Sixth compressed air line

[0162] DL7 Seventh compressed air line

[0163] DL8 Eighth compressed air line

[0164] KL1 First cooling medium line

[0165] KL2 Second cooling medium line

[0166] KL3 Third cooling medium line

[0167] KL4 Fourth cooling medium line

[0168] KL5 Fifth cooling medium line

[0169] KL6 Sixth cooling medium line

Claims

1. A compressed air generating device (2), comprising: a control and regulator (28); an electric motor (24) controllable and regulated by the control and regulator (28); at least one air compressor (16; 18) drivable by the electric motor (24); an air inlet (8), via which ambient air (L) can be sucked into the at least one air compressor (16; 18); at least one air cooler (20; 22), which is connected to the output of the at least one air compressor (16; 18); at least one air dryer (40), which is connected to the output of the at least one air cooler (20; 22); a cooling medium inlet opening (12), via which a liquid cooling medium can be supplied to the at least one air cooler (20; 22) and to other components of the compressed air generating device (2); a cooling medium delivery opening (14), through which the heated cooling medium can be discharged from the compressed air generating device (2); and at least one temperature sensor (73, 73', 73"), which is connected to the control and regulator (28) via a data or sensor line (59), characterized in that, in order to measure the cooling medium temperature, the temperature sensor (73, 73', 73") is arranged before the cooling medium inlet or after the cooling medium outlet of the air cooler (22) which is arranged as the last air cooler before the air dryer (40) in the compressed air flow direction.

2. The compressed air generating device according to claim 1, characterized in that: In order to measure the coolant temperature, the temperature sensor (73) is arranged upstream of a coolant inlet opening (12) of the compressed air generating device (2).

3. The compressed air generating device according to claim 1, characterized in that: To measure the coolant temperature, the temperature sensor (73') is arranged immediately upstream of the coolant inlet of the air cooler (22) which is arranged as the last air cooler upstream of the air dryer (40) in the compressed air flow direction.

4. The compressed air generating device according to claim 1, characterized in that: To measure the coolant temperature, the temperature sensor (73") is arranged as the next component after the coolant outlet of the air cooler (22) which is arranged as the last air cooler before the air dryer (40) in the compressed air flow direction.

5. The compressed air generating device (2) according to any one of claims 1 to 4, characterized in that: The air cooler (22) which is arranged as the last air cooler before the air dryer (40) in the flow direction of the compressed air is arranged so that the coolant can flow through it first when viewed in the flow direction of the coolant.

6. A compressed air generating device (2) according to any one of claims 1 to 5, comprising: an electric motor (24); two air compressors (16, 18) which can be driven by the electric motor (24) and act in sequence; an air inlet (8) through which ambient air (L) can be sucked in by means of a first air compressor (16); two air coolers for cooling the compressed air, the air coolers being constructed and arranged as intercoolers (20) or aftercoolers (22), wherein: The input end of the intercooler (20) is pneumatically connected to the output end of the first air compressor (16), wherein the output end of the intercooler (20) is pneumatically connected to the input end of the second air compressor (18), wherein the output end of the second air compressor (18) is pneumatically connected to the input end of the aftercooler (22), and wherein the output end of the aftercooler (22) is pneumatically connected to the input end of the air dryer (40); and a cooling medium inlet opening (12) through which cooling medium can be introduced to The intercooler (20) and the aftercooler (22) convey liquid cooling medium; and a cooling medium delivery opening (14) through which the heated cooling medium can be discharged, characterized in that the aftercooler (22) is arranged so that the cooling medium can flow through the aftercooler first when viewed from the flow direction of the cooling medium, and there is at least one temperature sensor (73, 73', 73''), and in order to measure the temperature of the cooling medium, the temperature sensor is arranged before or after the aftercooler (22) along the flow direction.

7. The compressed air generating device according to claim 6, characterized in that: The electric motor (24), the 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) pneumatically connecting the output of the air dryer (40) to at least one external compressed air reservoir (45) and external compressed air consumers (51, 52), and the silencer (43) are arranged to cooperate with each other but are separated from each other.

8. The compressed air generating device according to claim 6, characterized in that: The electric motor (24), an inverter (26) for influencing the operation of the electric motor (24), the two air compressors (16, 18), the intercooler (20), the aftercooler, the air dryer (40), a multi-circuit protection valve (50) for pneumatically connecting the output of the air dryer (40) to at least one external compressed air reservoir (45) and external compressed air consumers (51, 52), and a silencer (43) are arranged in or on a common housing (6).

9. The compressed air generating device according to any one of claims 7 or 8, characterized in that: The control and regulator (28) is arranged separately or in or on the housing (6); the control and regulator (28) is connected to the inverter (26) via a first control line (54) for controlling the electric motor (24); the control and regulator (28) is connected to a two-position three-way solenoid switching valve (72) via a second control line (55); the two-position three-way solenoid switching valve is used to open or close a regeneration line (DL5a) that pneumatically connects the compressed air reservoir (45) and the air dryer (40) at least indirectly; and the control and regulator (28) is connected to the multi-circuit protection valve (50) via a sensor line (56).

10. The compressed air generating device according to any one of claims 6 to 9, characterized in that: A compressor module (90), a compressed air cooling module (92), a dryer module (94) and a silencer module (96) with associated pneumatic, hydraulic and electrical lines are arranged in sequence in or on the housing (6), wherein the compressor module (90) comprises the electric motor (24), the inverter (26), the two air compressors (16, 18) and the control and regulator (28), wherein the compressed air cooling module (92) comprises the intercooler (20) and the aftercooler (22), wherein the dryer module (94) comprises the air dryer (40) and the multi-circuit protection valve (50), wherein the silencer module (96) comprises a silencer (43) with a silencer material (44), and wherein the silencer module (96) comprises at least one regeneration air outlet opening (34) for discharging regeneration compressed air into the surrounding environment.

11. The compressed air generating device according to any one of claims 6 to 10, characterized in that: The output end of the air dryer (40) is connected via a first check valve (29) closed in the direction of the air dryer (40) with the aid of a fifth compressed air line (DL5); the fifth compressed air line (DL5) leads to at least one compressed air reservoir (45) and to compressed air consumers (51, 52) via the multi-circuit protection valve (50); the regeneration compressed air input end (70) of the air dryer (40) is connected to the output end of the two-position three-way solenoid switching valve (72) via a second check valve (76) opened in the direction of the regeneration compressed air input end (70), a throttle element (75) and a first line branch (DL5b); the two-position three-way solenoid switching valve (72) is connected to the output end of the two-position three-way solenoid switching valve (72); The input end is connected to the fifth compressed air line (DL5) via a regeneration compressed air line (DL5a); when the two-position three-way solenoid switching valve (72) is operated, dry compressed air can be delivered to the air dryer (40) as regeneration compressed air via the two-position three-way solenoid switching valve (72), the first line branch (DL5b), the throttle element (75) and the first check valve (76); and when the two-position three-way solenoid switching valve (72) is operated, the regeneration compressed air can be supplied to the pneumatic control input end of the two-position two-way switching valve (39), and the two-position two-way switching valve (39) is assigned to the regeneration air output end (42) of the air dryer (40).

12. The compressed air generating device according to claim 11, characterized in that: The air dryer (40) has a collecting area (49), the input of which is pneumatically connected to the output of the aftercooler (22) via a fourth compressed air line (DL4), and the collecting area (49) is designed such that water condensed from the compressed air and entrained can accumulate in the collecting area and can be removed therefrom.

13. The compressed air generating device according to claim 12, characterized in that: A pressure-controlled, two-position, two-way switching valve (39) is assigned to the collection area (49) of the air dryer (40); a control input end of the pressure-controlled, two-position, two-way switching valve (39) is connected to an output end of the two-position, three-way solenoid switching valve (72) via a second line branch (DL5c); the two-position, two-way switching valve (39) is closed when not operated; the two-position, two-way switching valve (39) is regenerated by means of compressed air supplied to the air dryer (40) and supplied via the second line branch (DL5c). The regeneration compressed air can be switched from its closed position to its open position. When the two-position two-way switching valve (39) is open, the regeneration compressed air can be guided through the drying medium (41) of the air dryer (40) in the regeneration compressed air flow (77). After flowing through the drying medium (41), the regeneration compressed air can be guided to the collecting area (49) of the air dryer (40) and can entrain the accumulated condensate there. The regeneration compressed air can also leave the air dryer (40) via the regeneration air outlet (42).

14. The compressed air generating device according to any one of claims 9 to 13, characterized in that: Instead of the two-position three-way solenoid switching valve (72), there are two two-position two-way solenoid switching valves that can be driven by the control and regulator (28), wherein the first two-position two-way solenoid switching valve is arranged in the first line branch (DL5b) before the throttle element (75) in the flow direction of the regeneration compressed air, wherein the second two-position two-way solenoid switching valve is arranged in the second line branch (DL5c) before the pressure-controlled two-position two-way switching valve (39), and wherein the fifth compressed air line (DL5) is directly connected to the first line branch (DL5b) and directly connected to the second line branch (DL5c) before the two two-position two-way solenoid switching valves in the flow direction of the regeneration compressed air.

15. The compressed air generating device according to any one of claims 1 to 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 which is connected to the control and regulator (28) via a data or sensor line (59).

16. Method for operating a compressed air generating system (2) having the features of at least one of the system claims, wherein: Air compressed by means of at least one air compressor (16, 18) is cooled in at least one air cooler (20, 22), wherein the cooled compressed air is supplied to an air dryer (40) and dried there, wherein the dried compressed air is supplied to a compressed air consumer (51, 52) and / or to at least one compressed air reservoir (45), and wherein, in order to regenerate a drying medium (41) arranged in the air dryer (40), a certain regeneration compressed air volume of dry compressed air is passed through the drying medium and subsequently discharged to the surrounding environment, characterized in that the regeneration compressed air volume required for regenerating the drying medium (41) is calculated at least in dependence on the temperature of the cooling medium before and / or after flowing through the air cooler (22) which is the last air cooler (22) arranged before the air dryer (40), and the regeneration compressed air volume of dry compressed air determined in this way is subsequently passed through the air dryer (40).

17. The method according to claim 16, characterized in that The coolant temperature upstream of the coolant inlet opening (12) of the compressed air generating device (2) is measured by means of a first temperature sensor (73), and the regeneration compressed air volume respectively required for drying the drying medium (41) in the air dryer (40) is directed through the air dryer (40) in a controlled and / or regulated manner as a function of the measured coolant temperature.

18. The method according to claim 16, characterized in that The second temperature sensor (73') measures the cooling medium temperature upstream of the cooling medium inlet of the air cooler (22) which is immediately adjacent to the last air cooler arranged upstream of the air dryer (40) in the compressed air flow direction, and guides the regeneration compressed air volume required for drying the drying medium (41) in the air dryer (40) through the air dryer (40) in a controlled and / or regulated manner depending on the measured cooling medium temperature.

19. The method according to claim 16, characterized in that The cooling medium temperature after the cooling medium outlet of the air cooler (22) which is arranged as the last air cooler before the air dryer (40) in the compressed air flow direction is measured by means of a third temperature sensor (73"), and the regeneration compressed air volume respectively required for drying the drying medium (41) in the air dryer (40) is guided through the air dryer (40) in a controlled and / or regulated manner depending on the measured cooling medium temperature.

20. The method according to claim 16, characterized in that The temperature of an inverter (26) provided for controlling and regulating the electric motor (24) is measured, the measured temperature of the inverter (26) is used to calculate the coolant temperature in the air cooler (22) which is the last air cooler (22) arranged before the air dryer (40) in the compressed air flow direction, and the regeneration compressed air volume required for drying the drying medium (41) in the air dryer (40) is guided through the air dryer (40) in a controlled and / or regulated manner depending on the coolant temperature thus determined.

21. Method for operating a compressed air generating plant (2), the method having the features of at least one of the plant claims and having the features of at least one of the method claims 16 to 22, characterized in that The method has the following steps: a) sucking in ambient air by means of a first air compressor (16), b) pre-compressing the sucked ambient air to a first air pressure value in the first air compressor (16), c) cooling the intercooler (20) with a liquid cooling medium, 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 the aftercooler (22) with a liquid cooling medium, wherein the aftercooler, viewed in the flow direction of the cooling medium, is hydraulically reached by the cooling medium as the first air cooler, 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) The cooled and dried compressed air is forwarded to compressed air consumers (51, 52) and / or to at least one compressed air reservoir (45).

22. The method according to claim 21, characterized in that The method further comprises the following method steps: j) transferring the liquid cooling medium from the aftercooler (22) to the intercooler (20), k) transferring the liquid cooling medium from the intercooler (20) to a cooling device (25) of the electric motor (24), 1) transferring liquid cooling medium from the cooling device (25) of the electric motor (24) to the cooling device (48) of the second air compressor (18), m) transferring liquid cooling medium from the cooling device (48) of the second air compressor (18) to the cooling device (27) of the inverter (26), n) transferring liquid cooling medium from the cooling device (27) of the inverter (26) to the cooling device (46) of the first air compressor (18), o) transferring liquid cooling medium from the cooling device (46) of the first air compressor (18) to an external cooling device (82).

23. The method according to any one of claims 16 to 22, characterized in that The time interval between two regeneration processes for drying a drying medium (41) of the air dryer (40) is controlled and / or regulated as a function of the temperature of the cooling medium at an output of the external cooling device (82) or at an input of the aftercooler (22).

24. The method according to any one of claims 16 to 23, characterized in that The time interval between two regeneration processes for drying a drying medium (41) of the air dryer (40) is controlled and / or regulated as a function of the ambient temperature.

25. The method according to any one of claims 16 to 24, characterized in that The respectively required regeneration compressed air volume for drying the drying medium (41) is controlled and / or regulated as a function of the ambient temperature.

26. The method according to any one of claims 16 to 25, characterized in that The volume of regeneration compressed air respectively required for drying the drying medium (41) or the duration and / or frequency of the regeneration process are controlled and / or regulated as a function of the difference between the ambient temperature and the temperature of the cooling medium.

27. The method according to any one of claims 16 to 26, characterized in that In the case of unregulated control of the regeneration of the drying medium (41) of the air dryer (40), a maximum temperature value of the cooling medium to be expected during operation of the compressed air production device (2) is determined, this value of the cooling medium temperature is used as a basis for determining a maximum regeneration compressed air volume, and a regeneration process for the drying medium (41) associated therewith is carried out using the maximum regeneration compressed air volume.

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