Compressed air system for a motor vehicle

Patent metadata

Field	Value
Publication number	US-10173616-B2
Application number	US-201515521525-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Oct 30, 2014
Publication date	Jan 8, 2019
Grant date	Jan 8, 2019

Abstract

A compressed air system for a motor vehicle with an air supply system, including: an electric drive motor, which can be controlled for variable speed, an air compressor coupled to be driven by the electric drive motor, an electric power supply for supplying electric power to the electric drive motor, at least one air reservoir connected with the air compressor to receive air from the air compressor, an air utilization system connected to the at least one air reservoir to receive air from the at least one air reservoir, a controller to control the speed of the electric drive motor. The controller controls the electric drive motor to determine the speed of the electric drive motor so that during filling of the air reservoir, when the pressure level in the air reservoir passes a setpoint that is between a minimum level and a higher cut off pressure level, the controller changes the compressor speed so that specific power consumption per unit mass of air compressed is decreased.

First claim

The invention claimed is:

1. A compressed air system for a motor vehicle with an air supply system, comprising:
an electric drive motor, which is controllable for variable speed;
an air compressor coupled to be driven by the electric drive motor;
an electric power supply to supply electric power to the electric drive motor;
at least one air reservoir connected with the air compressor to receive air from the air compressor;
an air utilization system connected to the at least one air reservoir to receive air from the at least one air reservoir;
a controller to control the speed of the electric drive motor;
wherein the controller controls the electric drive motor to determine the speed of the electric drive motor depending upon at least one signal out of the following signals:
a signal representing the activation status of an accelerator pedal of the vehicle,
a signal representing the speed of the vehicle,
a signal representing the temperature of the power supply,
a signal representing the temperature of the electric drive motor,
a signal representing the wetness level of the air compressed by the air compressor,
a signal representing the load of the air compressor,
a signal representing the running time of the air compressor,
a signal representing the status of the electric power supply;

wherein during filling of the air reservoir, when the pressure level in the air reservoir passes a setpoint that is between a minimum level and a higher cut off pressure level, the controller changes the compressor speed so that specific power consumption per unit mass of air compressed is decreased.

2. The compressed air system of claim 1 , wherein in at least one interval of pressure in the air reservoir, the compressor speed is regulated by the controller so that a mass flow of air is delivered that is proportional to a ratio between (i) the difference between the cut off pressure level and the actual pressure in the air reservoir and (ii) the remaining time in the on load phase of the compressor.

3. The compressed air system of claim 1 , wherein while the pressure in the air reservoir is above a minimum level, and wherein the controller transforms an increase in vehicle speed into an increase in compressor speed and/or transforms a decrease in vehicle speed into a decrease in compressor speed, according to a predefined function.

4. The compressed air system of claim 1 , wherein the controller optimizes the compressor speed so as to avoid at least one pre-set interval of compressor speeds.

5. The compressed air system of claim 4 , wherein compressor speeds in the pre-set interval are disallowed by the controller and/or penalized in a merit function that the controller uses to rate compressor speeds.

6. The compressed air system of claim 4 , wherein when the controller changes the compressor speed from a first value on one side outside the pre-set interval to a second value on the other side outside the pre-set interval, the compressor is set to cross the pre-set interval of speeds at its maximum slew rate.

7. The compressed air system of claim 1 , wherein the electric power supply, the controller and the electric drive motor are connected by an electric power supply network, and wherein the controller controls the electric drive motor to determine the speed of the electric drive motor depending upon a signal representing the status of the electric power supply network.

8. The compressed air system of claim 7 , wherein the signal representing the status of the electric network) is the voltage and/or the conducted current.

9. The compressed air system of claim 1 , wherein the speed of the electric drive motor is determined based upon at least one function and/or upon at least one look-up table, where at least one of the signals is an input variable for the at least one function and/or the least one look-up table.

10. The compressed air system of claim 1 , wherein the speed of the electric drive motor is determined based upon the air consumption of the compressed air system of the vehicle.

11. The compressed air system of claim 1 , wherein the speed of the electric drive motor is controlled by the controller so that (i) if the pressure level in the air reservoir is lower than a minimum level and if the power stage of the electric power supply reaches or exceeds a set power stage limit, then the electric drive motor is operated with its maximum speed until the pressure level in the air reservoir reaches a cut off pressure level, or (ii) if the pressure level in the air reservoir is below a set pressure limit and if the power stage of the electric power supply is below the set power stage limit, then the electric drive motor is operated with a speed between zero speed and its maximum speed, until the pressure level in the air reservoir reaches the cut off pressure level.

12. The compressed air system of claim 1 , wherein the speed of the electric drive motor is controlled by the controller so that, if the pressure in the air system reservoir is below a set pressure limit, then the electric drive motor is controlled to operate with a speed calculated to cover the actual air consumption of the compressed air system, until the pressure level in the air reservoir reaches a set cut off pressure level.

13. The compressed air system of claim 1 , wherein the speed of the electric drive motor is controlled by the controller so that, if the pressure in the air system reservoir is below a set pressure limit, then the electric drive motor is operated with a speed calculated to cover the current air consumption of the compressed air system, until the pressure level in the air reservoir reaches a cut off pressure level, which is higher than a normal cut off pressure level to store more energy in the compressed air system.

14. The compressed air system of claim 1 , wherein the speed of the electric drive motor is controlled by the controller so that, if the power stage of the electric power supply is below a set power stage limit, or if the temperature of the electric drive motor exceeds a critical temperature limit, or if the actual speed of the electric drive motor is not equal to a demanded speed, then the electric drive motor will be stopped.

15. The compressed air system of claim 1 , wherein the electric drive motor is controlled by the controller so that, if the compressor is switched offload and the actual speed of the electric drive motor of the compressor is higher than zero, the electric drive motor is operated in a generator mode to charge the electric power supply until a set or predetermined charge level of the electric power supply is reached.

16. The compressed air system of claim 1 , wherein the electric drive motor is controlled by the controller so that, if an accelerator pedal of the drive engine of the vehicle is kicked down and the charge status of the electric power supply exceeds a set charge limit and the consumption of electric power is above a set consumption limit, than the electric drive motor of the compressor is controlled to operate with a calculated speed lower than its maximum speed until the pressure in the air system reservoir reaches a set cut off pressure level.

17. The compressed air system of claim 1 , wherein the electric drive motor is controlled by the controller so that, if the ambient temperature is below a set ambient temperature, the electric drive motor is controlled to operate with a set calculated speed until the pressure level in the air system reservoir reaches a cut off pressure level.

18. The compressed air system of claim 1 , wherein

Assignees

• Knorr Bremse Systeme Fuer Nutzfahrzeuge Gmbh

Inventors

• Adler Tamas
• Nemeth Huba

Classifications

• B60G11/26

  having fluid springs only, e.g. hydropneumatic springs ({B60G11/006,} B60G15/12 take precedence) · CPC title

• B60T13/261

  systems with both indirect application and application by springs or weights and released by compressed air · CPC title

• B60T13/683

  in pneumatic systems or parts thereof (in vacuum systems B60T13/72) · CPC title

• B60R16/08 Primary

  fluid · CPC title

• B60T13/662 Primary

  characterised by specified functions of the control system components · CPC title