DE102022106496A1 - Compressed air generating device of a vehicle and method for operating it - Google Patents

Abstract

The invention relates to a compressed air generating device (2) of a vehicle, which has a suction inlet (38), a pressure outlet (40) and a venting outlet (42), and with at least two compressor units (18, 20) that can be driven by an electric motor (14), wherein the inlet of the first compressor unit (18) is connected to the suction inlet (38), the outlet of the first compressor unit being connected to the inlet of an intercooler (26), the outlet of the intercooler being connected to an inlet of a 5/3-way Switching valve designed switching valve (52) is connected, an output of the switching valve being connected to the input of the second compressor stage, the output of the second compressor stage being connected to the pressure outlet (40) via an aftercooler (28) or via a vent valve (54). a vent outlet (42) can be connected, and wherein the two compressor units can be operated alternately in parallel or in series by switching the changeover valve. In order for the compressed air generating device and the components and actuators supplied with compressed air to function trouble-free even at low temperatures, it is provided that the inlet and the outlet of the intercooler (26) are connected to one another via a bypass line (76), and that in the bypass -Line a bypass valve (56) designed as a 2/2-way switching valve is arranged, by means of which the bypass line is shut off in a rest position of the bypass valve (56) and opened in its switching position.

Description

The invention relates to a compressed air generating device of a vehicle, which has a suction inlet, a pressure outlet and a venting outlet, and with at least two compressor units that can be driven by an electric motor, the inlet of the first compressor unit being connected to the suction inlet, the outlet of the first compressor unit being connected to the inlet an intercooler is connected, the output of the intercooler being connected to an input of a switching valve designed as a 5/3-way switching valve, an output of the switching valve being connected to the input of the second compressor stage, the output of the second compressor stage via an aftercooler is connected to the pressure outlet or can be connected to a venting outlet via a venting valve, and wherein the two compressor units can be operated alternately in parallel or in series by switching the changeover valve. The invention also relates to a method for operating this compressed air generating device.

Vehicles, especially commercial vehicles, can be equipped with several compressed air consumer circuits, such as a compressed air brake system and an air suspension system. To generate the compressed air required for the operation of the compressed air consumer circuits, a compressed air generating device with at least one compressor is required, which can be driven by the drive motor of the vehicle or by a separate electric motor.

In order to be able to meet different requirements that arise when the vehicle is driving, such as a high delivery volume flow or a high delivery pressure, at least two compressors or one compressor with two compressor units are provided, which can be operated in parallel or in series if necessary.

When operating in parallel, both compressors or compressor units suck in air from the environment and compress it to a medium delivery pressure, which results in a high delivery volume flow. A high delivery volume flow is advantageous when starting up the vehicle to fill the storage containers of the compressed air consumer circuits, which are largely empty after a long period of standstill, or during driving after several successive braking processes to fill the largely empty storage containers of the service brake circuits. Likewise, a high delivery volume flow is advantageous when a major leak occurs in one of the compressed air consumer circuits or the compressed air generating device in order to maintain the functionality of the most important compressed air consumer circuits, in particular the service brake circuits, and thus to enable onward travel to a repair workshop, at least in emergency operation.

In series-connected operation, one of the two compressors or one of the two compressor units of a compressor sucks in air from the environment and compresses it to a medium delivery pressure. The air pre-compressed in this way is then fed to the further compressor unit and compressed by it to a high delivery pressure. The high delivery pressure is necessary in order to achieve a maximum storage pressure when the storage containers of the compressed air consumer circuits are largely filled, which is required, for example, in order to be able to brake the vehicle with maximum braking deceleration in the event of an emergency braking. In order to increase the efficiency of the compressed air generating device and to protect downstream valves and other components from overheating, the compressor units are each provided with a cooler of a cooling circuit through which a coolant flows, by means of which the compressed air heated due to its compression is cooled and the delivery volume flow is increased.

From the DE 10 2008 023 594 A1 a compressor device with at least two compressors is known, which can be connected in parallel in a first operating mode and operated in series in a second operating mode. Switching between the two operating modes is done by switching a 2/2-way valve and a 3/2-way valve in an assigned valve arrangement. In a first embodiment of this compressor device, the valve arrangement has pressure-controlled valves, the control inputs of which are connected via a control line to a storage container connected to the compressor device on the output side and can therefore be controlled depending on the filling pressure present in the storage container. According to a second embodiment of the compressor device, the valves of the valve arrangement are designed as solenoid switching valves, the switching magnets of which are connected to an electronic control device via electrical control lines. The electronic control device is also connected to a pressure sensor connected to the storage container via an electrical sensor line, so that the valves of the valve arrangement can also be controlled in this embodiment depending on the filling pressure in the storage container. In the second operating mode, the compressed air pre-compressed by the first compressor is passed through an intercooler before entering the second compressor.

In the DE 10 2010 047 821 A1 an air compression device of a vehicle is shown and described with an air compressor comprising at least two compressors, which can be switched between a series-connected operating mode of the compressors and a parallel-connected operating mode of the compressors. Switching between the two operating modes takes place via a solenoid valve of a valve device, which is designed as a 5/2-way switching valve. A cooler is connected downstream to each of the two compressors. In the operating mode of the two compressors connected in parallel, the compressed air compressed in the first compressor and cooled in the first cooler also flows through the cooler behind the second compressor. In a preferred application, the air compression device is supplied on the input side with a portion of the charge air of an internal combustion engine used as the drive motor of the vehicle, which has been pre-compressed in a turbocharger and cooled in an intercooler.

In addition, it is from the unpublished one DE 10 2021 121 424.6 a multi-stage, electrically driven compressor for generating compressed air for a compressed air supply system of a commercial vehicle is known. The compressor has a cooling system that can be operated using a fluid coolant and can be connected to a cooling system of the commercial vehicle. The compressor is designed as a rotary compression unit and has an electric motor and an inverter, the inverter being used to supply energy and to control and regulate the electric motor. In addition, the compressor has a first compression stage and at least one second compression stage, which are pneumatically connected to one another via an intercooler. The second compression stage is pneumatically connected to a compressed air outlet via an aftercooler and a check valve. The components integrated in the cooling system and to be cooled, namely the electric motor, inverter, first compression stage, intercooler, second compression stage and aftercooler, are arranged in series or parallel to one another in the flow of a coolant.

Against this background, the present invention is based on the object of presenting a compressed air generating device of the type mentioned, which has an expanded range of functions and improved operating properties compared to the known compressor and air compression devices. In addition, a method will be described with which this compressed air generating device can be operated advantageously.

The device-related task is solved by means of a compressed air generating device which has the features of claim 1. The features of further developments of the compressed air generating device are mentioned in dependent claims. Independent method claims define methods for operating this compressed air generating device.

Accordingly, the invention relates to a compressed air generating device of a vehicle, which has a suction inlet, a pressure outlet and a venting outlet. There are also at least two compressor units that can be driven by an electric motor. The inlet of the first compressor unit is connected to the suction inlet, and the outlet of the first compressor unit is connected to the inlet of an intercooler. Furthermore, the output of the intercooler is connected to an input of a switching valve designed as a 5/3-way switching valve, with an output of this switching valve being connected to the input of the second compressor stage. It is also provided that the output of the second compressor stage is connected to the pressure outlet via an aftercooler or can be connected to a venting outlet via a vent valve. In addition, the two compressor units can be operated alternately in parallel or in series by switching the changeover valve.

To solve the device-related task, this compressed air generating device provides that the inlet and the outlet of the intercooler are connected to one another via a bypass line, and that a bypass valve designed as a 2/2-way switching valve is arranged in the bypass line is by means of which the bypass line is shut off in a rest position of the bypass valve and opened in a switching position of the bypass valve.

The compressed air generating device thereby has an expanded range of functions and improved operating properties compared to the known compressed air generating devices. In order to avoid icing up of valves and other components of the compressed air generating device as well as compressed air consumer circuits that can be supplied with compressed air at a low ambient temperature, in particular at a temperature below 5 ° Celsius, it is therefore provided that the inlet and the outlet of the first intercooler are connected via a bypass -Line are connected to each other. A bypass valve designed as a 2/2-way switching valve is arranged in this bypass line, by means of which the bypass line is shut off in a rest position of the bypass valve and opened in a switching position of the bypass valve. In the locked resting position of the Through the bypass valve, compressed air flows through the intercooler and thus cools the compressed air that is compressed and thereby heated by the first compressor unit. In the open switching position of the bypass valve, compressed air practically does not flow through the intercooler due to its greater flow resistance, but is bypassed via the bypass line, so that the compressed air compressed and thereby heated by the first compressor unit is not cooled here, which is the case at low ambient temperatures described is advantageous.

According to a first development of this compressed air generating device, it is provided that the switching valve designed as a 5/3-way switching valve has two input connections and three output connections, of which the first input connection has the suction inlet, the second input connection has the output of the intercooler, and the first output connection has the pressure output, the second output port is connected to the inlet of the second compressor unit, and the third output port is connected to the vent outlet. This changeover valve is also designed in such a way that in a rest position of the changeover valve, the second input port is connected to the second output port and the remaining ports are shut off, so that in a first switching position of the changeover valve, the first input port is connected to the second output port and the second input port to the first Output port is connected and the third output port is blocked, and that in a second switching position of the changeover valve, the second input port is connected to the third output port and the remaining ports are blocked.

Due to this design of the changeover valve and its connection to pneumatic lines of the compressed air generating device, three functions can be switched with the changeover valve. In the rest position of the changeover valve, in which the second input port is connected to the second output port, the two compressor units are connected in series, which results in a high delivery pressure in conjunction with a medium delivery volume flow during operation.

In the first switching position of the changeover valve, in which the first input port is connected to the second output port and the second input port is connected to the first output port, the two compressor units are connected in parallel, whereby compressed air with a high delivery volume flow can be generated in conjunction with a medium delivery pressure.

In the second switching position of the changeover valve, in which the second input port is connected to the third output port, the compressed air line connected to the output of the first compressor unit is vented, whereby the electric motor accelerates to its target speed more quickly when it is switched on due to the lack of back pressure in the first compressor unit which is required for the desired delivery pressure or the desired delivery volume flow.

In order to further relieve the load on the electric motor when it is switched on, it is provided that a pressure line is arranged between the output of the second compressor unit and the inlet of the aftercooler, that a vent line is connected to this pressure line and routed to the vent outlet, and that in the vent line the 2 /2-way switching valve designed vent valve is arranged, by means of which the vent line is shut off in a rest position of the vent valve and opened in a switching position of the vent valve. By switching the vent valve to its switching position, the compressed air line connected to the output of the second compressor unit is also vented and the electric motor is thus relieved of the load when switched on due to the lack of back pressure from the second compressor unit.

In order to avoid a backflow of compressed air from the pressure output into the two compressor units and from these into the environment via the suction inlet when the electric motor is switched off, the output of the first compressor unit and the output of the aftercooler as well as the second output connection of the changeover valve are each provided with a check valve that blocks the return flow direction subordinate.

To achieve a simple and compact structure, the two compressor units can preferably be driven by the electric motor via a common drive shaft. In order to be able to drive at least one of the two compressor units in the case of a weak electrical system, it is advantageously provided that at least the second compressor unit is connected to the drive shaft of the electric motor via a disengageable and engageable separating clutch and can therefore be decoupled from the electric motor.

Since the electric motor heats up considerably during operation and can be damaged by overheating, the electric motor is preferably connected to the cooling circuit which also supplies the intercooler and the aftercooler with a liquid coolant.

The two coolers and the electric motor are arranged in a coolant line of the cooling circuit in the flow direction of the coolant, preferably in the order of electric motor, intercooler and aftercooler between a coolant inlet and a coolant outlet. This corresponds to the ascending order of the operating temperatures of these components and ensures the best possible cooling.

The ventilation outlet usually leads to the environment via a silencer. According to an advantageous development of the compressed air generating device, however, a blow-out line is connected to the ventilation outlet. The blow-out line leads to the environment via an air filter and/or a particle separator, which is also arranged in the suction line, as well as a check valve that blocks the return flow direction and a silencer. Thus, in this embodiment of the compressed air generating device, the compressed air flowing out when the compressed air lines are vented is used to blow out or clean the air filter and/or particle separator arranged in the suction line.

The changeover valve, the vent valve and the bypass valve are preferably designed as solenoid switching valves. It is also provided that the separating clutch on the second compressor unit can be disengaged and engaged by means of an electromagnetic clutch actuator. The solenoid switching valves and the clutch actuator can therefore be controlled by the electronic control unit via electrical control lines, which, compared to pressure control of the switching valves and the clutch actuator, which is also possible, enables faster switching of the switching valves and faster disengagement and engagement of the separating clutch.

To achieve compact dimensions and easy installation in the vehicle, the electric motor, the two compressor units, the intercooler, the aftercooler and the cooling circuit with the coolant inlet, the at least one coolant line and the coolant outlet are preferably combined in a compressor block and arranged in a common compressor housing.

With the same objective, the changeover valve, the vent valve, the bypass valve and the two check valves as well as the suction inlet, the pressure outlet and the vent outlet are advantageously combined in a distribution block and arranged in a common valve housing. The electronic control unit can be integrated into the distribution block or attached externally to the valve housing. The tasks of the electronic control unit can also be performed by another control unit in the vehicle.

The line sections of the suction lines, pressure lines, connecting lines and vent lines running between the compressor housing and the valve housing can be connected to one another via sealed plug connections or flange screw connections.

Further Finally, it can be provided that a temperature sensor is present for measuring the ambient temperature, which is connected to the electronic control unit via a sensor line. The electronic control unit can also receive information about the current ambient temperature via a CAN bus line, because such a temperature sensor is usually present in all modern vehicles, and its temperature measurements are offered to all connected devices for use via the CAN bus. The compressed air generating device with the features of the invention uses the measured values about the ambient temperature to control the actuation of the bypass valve mentioned.

Finally, it is preferably provided that a pressure sensor for measuring the pressure of the compressed air generated is present behind the pressure outlet of the compressed air generating device. This pressure sensor is connected to the electronic control unit via a sensor line. The pressure sensor can measure the pressure of the compressed air, for example in a compressed air storage container or in a compressed air consumer circuit.

The invention also relates to a method for operating the compressed air generating device described, in which it is provided that the ambient temperature is measured by means of the temperature sensor mentioned and that the bypass valve designed as a 2/2-way solenoid switching valve is switched from a closed rest position to an open switching position when the ambient temperature has fallen below a predetermined minimum temperature, and that the bypass valve is switched back to the rest position mentioned when the ambient temperature has reached or exceeded the minimum temperature. The minimum temperature can, for example, be a value between 5° and 0° Celsius, including the range limits mentioned.

As mentioned, in the shut-off rest position of the bypass valve, the compressed air flows through the intercooler and thus cools the compressed air that is compressed and thereby heated by the first compressor unit. In the open switching position of the bypass valve, the intercooler is practically not flowed through by compressed air due to its greater flow resistance, but is bypassed via the bypass line, so that the compressed air compressed and thereby heated by the first compressor unit is no longer cooled, which is advantageous at low ambient temperatures as described.

Furthermore, it can be provided according to the method that the supply pressure present in at least one storage container of safety-relevant compressed air consumer circuits is measured by means of a pressure sensor, that the changeover valve designed as a 5/3-way switching valve moves from its rest position, in which the two compressor units are connected in series, to one first switching position is switched, in which the two compressor units are connected in parallel when the supply pressure has fallen below a predetermined minimum pressure, and that the changeover valve is switched back to its rest position when the supply pressure has reached or exceeded the minimum pressure.

This procedure is particularly advantageous because if the pressure falls below the minimum pressure mentioned, a high delivery volume flow has priority over a high delivery pressure in order to at least functionally maintain the functions of the safety-relevant compressed air consumer circuits, such as the service brake circuits.

According to another mode of operation of the compressed air generating device having the features of the invention, it can be provided that before the electric motor is switched on, the switching valve designed as a 5/3-way switching valve is switched to a second switching position for a set period of time, in which one is connected to the first compressor unit connected pressure line is connected to a ventilation outlet.

Alternatively or additionally, it can be provided that before the electric motor is switched on, the vent valve designed as a 2/2-way switching valve is switched from a closed rest position to an open switching position for a set period of time, in which a pressure line connected to the second compressor unit is switched over a vent line is connected to the vent outlet.

The last two procedures mentioned create the advantage that by eliminating the outlet counterpressure on the compressor units, the electric motor reaches the operating speed required for the desired delivery pressure or for the desired delivery volume flow more quickly than without these measures.

Finally, a compressed air generating device having the features of the invention can be operated in such a way that the charge state of a battery of an electrical vehicle electrical system, from which the electric machine is supplied with electrical energy, is measured, and that the separating clutch, via which the second compressor unit is connected to the drive shaft of the electric motor is connected, is disengaged when the charge level of the battery has fallen below a specified minimum charge level, and is engaged again when the charge level of the battery has reached or exceeded the minimum charge level.

By decoupling the second compressor unit from the drive shaft of the electric machine by means of the separating clutch, at least the first compressor unit can still be driven by the electric machine and thus compressed air can be generated when the battery is low.

• 1 eine Basisausführung einer erfindungsgemäßen Drucklufterzeugungseinrichtung in einer schematischen Darstellung, und
• 2 eine Weiterbildung einer erfindungsgemäßen Drucklufterzeugungseinrichtung gemäß 1, ebenfalls in einer schematischen Darstellung.

Compressed air generating devices with the features of the invention are explained in more detail using two exemplary embodiments shown in the accompanying drawing. Shown in the drawing

• 1 a basic version of a compressed air generating device according to the invention in a schematic representation, and
• 2 a further development of a compressed air generating device according to the invention 1 , also in a schematic representation.

The ones in the 1 Schematically illustrated basic version of a compressed air generating device 2 according to the invention of a vehicle, in particular a commercial vehicle, has a compressor block 4 with a compressor housing 6, a distributor block 8 with a valve housing 10 and an electronic control unit 12.

A coolable electric motor 14 with a drive shaft 16, a first compressor unit 18 and a second compressor unit 20 are arranged in the compressor block 4. The first compressor unit 18 can be driven directly by means of the drive shaft 16 of the electric motor 14. The second compressor unit 20 is connected to the drive shaft 16 of the electric motor 14 via a disengageable and engageable separating clutch 22. The separating clutch 22 can be disengaged and engaged by means of an electromagnetic clutch actuator 24. In addition, the compressor block 4 has an intercooler 26, which follows the first compressor unit 18 on the output side in the flow direction of the compressed air that can be generated is ordered. There is also an aftercooler 28, which is arranged downstream of the second compressor unit 20 on the output side.

A coolant line 34 of a cooling circuit 30 through which a liquid coolant flows during operation of the compressed air generating device 2 runs between a coolant inlet 32 and a coolant outlet 36 in the order of electric motor 14, intercooler 26 and aftercooler 28. This corresponds to the ascending order of the operating temperatures of these components and brings about the best possible result Cooling. The electric motor 14, the two compressor units 18, 20, the intercooler 26, the aftercooler 28 and the cooling circuit 30 with the coolant inlet 32, the coolant line 34 and the coolant outlet 36 are arranged in or on the compressor housing 6 of the compressor block 4.

The distributor block 8 has a suction inlet 38, a pressure outlet 40 and a vent outlet 42, which are arranged on the valve housing 10. An external suction line 44 with an air filter 46 is connected to the suction inlet 38. A compressed air line 41 is connected to the pressure outlet 40, which leads, for example, via a pressure regulator (not shown) and a multi-circuit protection valve 43 to at least one storage container 92 for compressed air and several compressed air consumer circuits 94. An external ventilation line 48 is connected to the ventilation outlet 42, the other end of which is connected to a first silencer 50. Compressed air can be released into the environment via this first silencer 50. Within the valve housing 10, the distributor block 8 has a changeover valve 52, a vent valve 54, a bypass valve 56 and two check valves 58, 60.

The changeover valve 52 is designed as a 5/3-way solenoid switching valve with two input ports and three output ports. The first input port of the switching valve 52 is connected to the suction inlet 38 via a first suction line branch 62a. The second input port of the changeover valve 52 is connected to the output of the first compressor unit 18 via a second pressure line 64b, the intercooler 26, the first check valve 58 and a first pressure line 64a. The first output connection of the switching valve 52 is connected to the pressure output 40 via a third pressure line 66 and the second check valve 60. The second output port of the changeover valve 52 is connected to the inlet of the second compressor unit 20 via a connecting line 68, and the third output port is connected to the vent outlet 42 via a vent line 70.

In a rest position of the switching valve 52, the second input port is connected to the second output port and the remaining ports are shut off. In a first switching position of the switching valve 52, the first input port is connected to the second output port and the second input port is connected to the first output port and the third output port is shut off. In a second switching position of the switching valve 52, the second input port is connected to the third output port and the remaining ports are shut off.

A fourth pressure line 72 extends with a first pressure line section 72a from the outlet of the second compressor unit 20 to the inlet of the aftercooler 28. From there, a second pressure line section 72b of the fourth pressure line 72 extends via the second check valve 60 to the pressure outlet 40. At that First pressure line section 72a is connected to a vent line 74, which is led to the vent outlet 42 via the aforementioned vent valve 54. The vent valve 54 is designed as a 2/2-way solenoid switching valve, by means of which the vent line 74 is shut off in a rest position of the vent valve 54 and is opened in a switching position of the vent valve 54.

The first pressure line 64a and the second pressure line 64b are connected to one another via a bypass line 76, in which the already mentioned bypass valve 56 is arranged. The bypass valve 56 is designed as a 2/2-way solenoid switching valve, by means of which the bypass line 76 is shut off in a rest position of the bypass valve 56 and is opened in a switching position of the bypass valve 56. Accordingly, the compressed air pre-compressed by the first compressor unit 18 will largely be directed past the intercooler 26 when the bypass valve 56 is open, as a result of which the compressed air in the compressed air generating device 2 is hardly cooled here.

The electric motor 14, the clutch actuator 24, the switching valve 52, the vent valve 54 and the bypass valve 56 are by means of in the 1 Electrical control lines (not designated) are connected to the electronic control unit 12 and can therefore be controlled by it. The line sections of the suction, pressure, connection and vent lines 62b, 64a, 64b, 68, 72b, 74 running between the compressor block 4 and the distribution block 8 are connected to one another in a manner not shown in detail via sealed plug connections or flange screw connections.

The two are in the respective rest position of the changeover valve 52 and the bypass valve 56 Compressor units 18, 20 connected in series. When the electric motor 14 is running, the first compressor unit 18 sucks in air from the environment via the second suction line branch 62b connected to its input and the external suction line 44 and compresses it. The compressed air pre-compressed in this way reaches the second compressor unit 20 via the first pressure line 64a, the first check valve 58, the intercooler 26, the second pressure line 64b, the changeover valve 52 and the connecting line 68, in which the compressed air is further compressed with the separating clutch 22 engaged.

The compressed air, which is highly compressed as a result, reaches the pressure outlet 40 via the first pressure line section 72a and the second pressure line section 72b of the fourth pressure line 72, the aftercooler 28 and the second check valve 60. From the pressure outlet 40, the compressed air is led via the compressed air line 41 to a multi-circuit protection valve 43, from which the compressed air is directed as required to at least one storage container 92 and to connected compressed air consumer circuits 94.

Operation of the two compressor units 18, 20 connected in series corresponds to the normal operation of the compressed air generating device 2 while driving with the storage container 92 largely full and the compressed air consumer circuits 94 well supplied.

The high delivery pressure achieved in conjunction with a relatively low delivery volume flow is required in order to achieve a maximum supply pressure, which is required, for example, in order to be able to brake the vehicle with maximum braking deceleration during emergency braking.

In the first switching position of the changeover valve 52, the two compressor units 18, 20 are connected in parallel and are operated in this way. With the electric motor 14 running and the separating clutch 22 engaged, both compressor units 18, 20 suck in air from the environment via the external suction line 44, namely the first compressor unit 18 via the second suction line branch 62b and the second compressor unit 20 via the first suction line branch 62a and the one mentioned Connecting line 68. The compressed air compressed by the first compressor unit 18 reaches the pressure outlet 40 via the first pressure line 64a, the first check valve 58, the intercooler 26, the second pressure line 64b, the changeover valve 52, the third pressure line 66 and the second check valve 60.

Deviating from this, the compressed air compressed by the second compressor unit 20 reaches the pressure outlet 40 via the first pressure line section 72a, the aftercooler 28, the second pressure line section 72b and the second check valve 60. A high delivery volume flow generated in this way is used when the vehicle is put into operation to fill up the after a relatively empty storage container 92 of the compressed air consumer circuits 94 or during driving after several consecutive braking operations to fill the largely empty storage containers 92 of the service brake circuits is advantageous.

In the second switching position of the changeover valve 52, the first and second pressure lines 64a, 64b connected to the first compressor unit 18 are connected to the ventilation outlet 42 via the changeover valve 52 and the vent line 70. Due to the lack of counterpressure in the first and second pressure lines 64a, 64b and in the first compressor unit 18, the electric motor 14 can be accelerated more quickly to its target speed when switched on, which is required for the desired delivery pressure or delivery volume flow. In order to relieve the second compressor unit 20 from the counterpressure present in the two pressure line sections 72a, 72b of the fourth pressure line 72 when the separating clutch 22 is engaged, in this case the vent valve 54 is also switched to its open switching position and the pressure line 72 is vented as a whole. Alternatively, to relieve the load on the electric motor 14, the separating clutch 22 can also be disengaged by means of the clutch actuator 24 and the second compressor unit 20 can thus be decoupled from the electric motor 14.

If there is a low ambient temperature when the vehicle is started up, in particular at temperatures below 0 ° Celsius, it is, as already mentioned, advantageous to switch the bypass valve 56 to its open switching position, whereby the compressed air compressed by the first compressor unit 18 bypasses the intercooler 26 and therefore is not cooled in this. The resulting relatively warm compressed air effectively protects subsequent valves and components from icing up.

The ambient temperature is measured by means of a temperature sensor 57, which is connected to the control unit 12 via a sensor line 59 or a CAN bus line. In addition, the compressed air generating device 2 has a pressure sensor 96, which is arranged here only as an example in the compressed air supply container 92 shown. This pressure sensor 96 is also connected to the control unit 12 via a sensor line 59* or a CAN bus line. By means of this pressure sensor 96, and if necessary a plurality of such pressure sensors, the currently prevailing pressure of the compressed air in the storage container 92 or in the compressed air consumer circuits 94 and used by the control device 12 to control and regulate the compressed air generating device 2.

The control unit 12 of the compressed air generating device 2 is integrated into an electrical vehicle electrical system, which also includes an electric battery 98. The control device 12 has or is assigned measuring means with which the state of charge of the electric battery 98 can be determined. If, based on a measurement, it turns out that the state of charge of the battery 98 has fallen below a specified minimum state of charge, the separating clutch 22 between the drive motor 14 and the second compressor unit 20 is disengaged. If it is determined that the state of charge of the battery 98 has reached or exceeded the minimum state of charge, the separating clutch 22 is re-engaged so that the second compressor unit 20 can participate in the production of compressed air. By decoupling the second compressor unit 20, at least the first compressor unit can still be driven by the electric machine when the battery charge level is low and compressed air can thus be generated.

One in 2 The second embodiment of a compressed air generating device 2′ shown schematically differs from the basic version of the compressed air generating device 2 according to 1 only in that a third check valve 78 that blocks the return flow direction, an air filter 80 provided with a cleaning outlet for cleaned intake air and a particle separator 82 with an electromagnetic vibrator 84 are arranged in the external suction line 44. In addition, a blow-out line 86 is connected to the ventilation outlet 42, which leads into the environment via the particle separator 82 and the air filter 80 as well as a fourth check valve 88 that blocks the return flow direction and a silencer 90.

The vibrator 84 is connected to the electronic control unit 12 via a control line and can therefore be controlled by it. In this second embodiment of the compressed air generating device 2 ', dirt particles deposited in the particle separator 82 can be advantageously removed by activating the vibrator 84 before the vehicle is put into operation, or when the storage container 92 of the compressed air consumer circuits 94 is largely full, even while driving. Afterwards or at the same time, with the changeover valve 52 switched to its second switching position and the vent valve 54 switched to its open position, these dirt particles are removed from the particle separator 82 and via the air filter 80 by means of the compressed air flowing out through the second vent line 70, the third vent line 74 and the blow-out line 86. the check valve 88 and the silencer 90 are blown out into the environment. This cleaning measure increases the effectiveness and service life of the air filter 80 and the particle separator 82 and avoids or at least reduces special cleaning and maintenance work on these two components 80, 82.

List of reference symbols (part of the description)

2

Compressed air generating device (first embodiment)

2'

Compressed air generating device (second embodiment)

4

compressor block

6

Compressor housing

8th

distribution block

10

Valve housing

12

Electronic control unit

14

Electric motor

16

drive shaft

18

First compressor unit

20

Second compressor unit

22

Separating clutch

24

Clutch actuator

26

Intercooler

28

Aftercooler

30

Cooling circuit

32

Coolant inlet

34

Coolant line

36

Coolant outlet

38

Suction inlet

40

Pressure output

41

Compressed air line

42

Vent outlet

43

Multi-circuit protection valve

44

suction line

46

Air filter (first embodiment)

48

First vent line

50

Silencer (first embodiment)

52

Switching valve, 5/3-way solenoid switching valve

54

Vent valve, 2/2-way solenoid switching valve

56

Bypass valve, 2/2-way solenoid switching valve

57

Temperature sensor

58

First check valve

59

First sensor line, CAN bus line

59*

Second sensor line, CAN bus line

60

Second check valve

62a

First suction line branch

62b

Second suction line branch

64a

First pressure line

64b

Second pressure line

66

Third pressure line

68

connecting line

70

Second vent line

72

Fourth pressure line

72a

First pressure line section of the fourth pressure line

72b

Second pressure line section of the fourth pressure line

74

Third vent line

76

Bypass line

78

Third check valve

80

Air filter (second embodiment)

82

particle separator

84

Shaker

86

exhaust line

88

Fourth check valve

90

Silencer (second embodiment)

92

Storage container for compressed air

94

Compressed air consumer circuits

96

Pressure sensor

98

Battery of the electrical system

QUOTES INCLUDED IN THE DESCRIPTION

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

Cited patent literature

• DE 102008023594 A1 [0006]
• DE 102010047821 A1 [0007]
• DE 1020211214246 [0008]

Claims (19)

Compressed air generating device (2, 2') of a vehicle, which has a suction inlet (38), a pressure outlet (40) and a venting outlet (42), and with at least two compressor units (18, 20) that can be driven by an electric motor (14), wherein the The input of the first compressor unit (18) is connected to the suction inlet (38), the output of the first compressor unit (18) being connected to the input of an intercooler (26), the output of the intermediate cooler (26) being connected to an input as 5 / 3-way switching valve (52) is connected, an output of the switching valve (52) being connected to the input of the second compressor stage (20), the output of the second compressor stage (20) being connected via an aftercooler (28). the pressure outlet (40) or can be connected to a vent outlet (42) via a vent valve (54), and wherein the two compressor units (18, 20) can be operated alternately in parallel or in series by switching the changeover valve (52), thereby characterized in that the inlet and the outlet of the intercooler (26) are connected to one another via a bypass line (76), and that in the bypass line (76) there is a bypass valve designed as a 2/2-way switching valve ( 56) is arranged, by means of which the bypass line (76) is shut off in a rest position of the bypass valve (56) and opened in a switching position of the bypass valve (56). Compressed air generating device (2, 2 '). Claim 1 , characterized in that the switching valve (52) designed as a 5/3-way switching valve has two input ports and three output ports, of which the first input port is connected to the suction inlet (38), the second input port is connected to the outlet of the intercooler (26), the first output port is connected to the pressure output (40), the second output port is connected to the inlet of the second compressor unit (20) and the third output port is connected to the vent outlet (42), wherein in a rest position of the changeover valve (52), the second input port is connected to the second Output port is connected and the remaining ports are shut off, wherein in a first switching position of the switching valve (52) the first input port is connected to the second output port and the second input port is connected to the first output port and the third output port is shut off, and wherein in a second switching position of the changeover valve (52), the second input port is connected to the third output port and the remaining ports are shut off. Compressed air generating device (2, 2 '). Claim 1 or 2 , characterized in that a pressure line (72) is arranged between the outlet of the second compressor unit (20) and the inlet of the aftercooler (28), a vent line (74) is connected to this pressure line (72) and to the vent outlet (42) is guided, and that in the vent line (74) the vent valve (54) designed as a 2/2-way switching valve is arranged, by means of which the vent line (74) is shut off in a rest position of the vent valve (54) and in a switching position of the vent valve (54) is open. Compressed air generating device (2, 2 ') according to one of Claims 1 until 3 , characterized in that the output of the first compressor unit (18) and the output of the aftercooler (28) are each followed by a check valve (58, 60) that blocks the return flow direction. Compressed air generating device (2, 2 ') according to one of Claims 1 until 4 , characterized in that the two compressor units (18, 20) can be driven by the electric motor (14) via a common drive shaft (16), and that at least the second compressor unit (20) is connected to the drive shaft via a disengageable and engageable separating clutch (22). (16) of the electric motor (20) is connected. Compressed air generating device (2, 2 ') according to one of Claims 1 until 5 , characterized in that only the electric motor (14), the intercooler (26) and the aftercooler (28) are connected to the cooling circuit (30) of the compressed air generating device (2, 2 '). Compressed air generating device (2, 2 '). Claim 6 , characterized in that the electric motor (14), the intercooler (26) and the aftercooler (28) are arranged in this order in the flow direction of the coolant between a coolant inlet (32) and a coolant outlet (36). Compressed air generating device (2') according to one of the Claims 1 until 7 , characterized in that a blow-out line (86) is connected to the ventilation outlet (42), and that the blow-out line (86) has an air filter (80) and/or a particle separator (82), which is also arranged in the suction line (44). is, and leads via a check valve (88) that blocks the return flow direction to a silencer (90), through which excess compressed air can be blown off into the environment. Compressed air generating device (2, 2 ') according to one of Claims 1 until 8th , characterized in that the changeover valve (52), the vent valve (54) and the bypass valve (56) are designed as magnetic switching valves, that the separating clutch (22) of the second compressor unit (20) can be disengaged via an electromagnetic clutch actuator (24) and can be engaged, and that the solenoid switching valves (52, 54, 56) and the clutch actuator (24) are connected to an electronic control unit (12) via electrical control lines. Compressed air generating device (2, 2 ') according to one of Claims 1 until 9 , characterized in that the electric motor (14), the two compressor units (18, 20), the intercooler (26), the aftercooler (28), the coolant inlet (32), at least one coolant line (34) and the coolant outlet (36) are combined in a compressor block (4) and arranged in a common compressor housing (6). Compressed air generating device (2, 2 ') according to one of Claims 1 until 10 , characterized in that the changeover valve (52), the vent valve (54), the bypass valve (56), the two check valves (58, 60), the suction inlet (38), the pressure outlet (40) and the vent outlet (42 ) are combined in a distributor block (8) and arranged in a common valve housing (10). Compressed air generating device (2, 2 '). Claim 10 and 11 , characterized in that the line sections of the suction, pressure, connection and vent lines (62b, 64a, 64b, 68, 72b, 74) running between the compressor housing (6) and the valve housing (10) are connected to one another via sealed plug connections or flange screw connections are connected. Compressed air generating device (2, 2 ') according to one of Claims 1 until 10 , characterized in that there is a temperature sensor (57) for measuring the ambient temperature, which is connected to the electronic control unit (12) via a sensor line (59). Compressed air generating device (2, 2 ') according to one of Claims 1 until 10 , characterized in that a pressure sensor (96) for measuring the pressure of the compressed air generated is present behind the pressure outlet (40) of the compressed air generating device (2. 2 '), which is connected to the electronic control unit (12) via a sensor line (59*). is. Method for operating the compressed air generating device (2, 2') according to at least one of the device claims, characterized in that the ambient temperature is measured by means of the temperature sensor (57), and that the bypass valve (56) designed as a 2/2-way solenoid switching valve is switched from a closed rest position to an open switching position when the ambient temperature has fallen below a predetermined minimum temperature, and that the bypass valve (56) is switched back to the rest position when the ambient temperature has reached or exceeded the minimum temperature. Method for operating the compressed air generating device (2, 2') according to at least one of the device claims, characterized in that the supply pressure present in at least one storage container (92) of safety-relevant compressed air consumer circuits (94) is measured by means of a pressure sensor (96), that is as 5/ 3-way switching valve (52) is switched from its rest position, in which the two compressor units (18, 20) are connected in series, to a first switching position in which the two compressor units (18, 20) are connected in parallel, when the supply pressure has fallen below a predetermined minimum pressure, and that the changeover valve (52) is switched back to its rest position when the supply pressure has reached or exceeded the minimum pressure. Method for operating the compressed air generating device (2, 2') according to at least one of the device claims, characterized in that before the electric motor (14) is switched on, the switching valve (52) designed as a 5/3-way switching valve is switched into a second Switching position is switched, in which a pressure line (64a, 64b) connected to the first compressor unit (18) is connected to a ventilation outlet (42). Method for operating the compressed air generating device (2, 2') according to at least one of the device claims, characterized in that before switching on the electric motor (14) for a set period of time, the vent valve (54) designed as a 2/2-way switching valve is switched off from a closed Rest position is switched to an open switching position, in which a pressure line (72; 72a, 72b) connected to the second compressor unit (20) is connected to the vent outlet (42) via a vent line (74). Method for operating the compressed air generating device (2, 2') according to at least one of the device claims, characterized in that the charge state of a battery (98) is one electrical vehicle electrical system, from which the electric machine (14) is supplied with electrical energy, is measured, and that the separating clutch (22), via which the second compressor unit (20) is connected to the drive shaft (16) of the electric motor (14), is disengaged is engaged when the charge level of the battery (98) has fallen below a specified minimum charge level, and is engaged again when the charge level of the battery (98) has reached or exceeded the minimum charge level.

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