Process for regulating the braking power of a supercharged internal combustion engine

• US 6,020,652 A
• Filed: 09/28/1998
• Issued: 02/01/2000
• Est. Priority Date: 09/26/1997
• Status: Expired due to Fees

• Current Assignee: DaimlerChrysler AG (Mercedes-Benz Group AG)
• Original Assignee: DaimlerChrysler AG (Mercedes-Benz Group AG)
• Inventors: Renninger, Peter, Sumser, Siegfried, Daudel, Helmut
• Primary Examiner(s): Ponomarenko, N.
• Application Number:
  US09/161,473
• Time in Patent Office: 491 Days
• Field of Search: 290/9, 290/17, 290/40 R, 290/40 A, 290/40 C, 290/45, 322/14, 180/170, 180/65.2, 180/338
• US Class Current: 290/45
• CPC Class Codes: F02B 37/24 by using pumps or turbines with adjustable guide vanes
• CPC Class Codes: F02B 41/10 in exhaust turbines use of exhaust turbines for charging F02B37/00
• CPC Class Codes: F02D 9/06 Exhaust brakes
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

In the engine braking operation of supercharged internal combustion engines, the braking power is generated by backing-up the exhaust gas before it enters an exhaust gas turbine of an exhaust gas turbocharger from an actuator in the exhaust gas duct. In order to make it possible to control the braking power within the operating limits of the exhaust gas turbocharger, the actual value and a maximum value of the turbine inlet pressure within the operating limits of the exhaust gas turbo supercharger are inferred from a performance graph of the internal combustion engine, which performance graph includes an electronically stored compressor performance graph of the supercharged air compressor which represents the relationship between mass throughput and total pressure ratio of the compressor and in which a plurality of engine operating lines for certain actuator positions and certain engine speeds as well as for a constant turbine inlet pressure are recorded. The maximum value arises as a function of the engine speed from a characteristic rotational speed line stored in the performance graph. Corresponding to the desired braking power, a nominal value which, together with the actual value of the turbine inlet pressure, serves in the control circuit as an inlet parameter for an engine controller for a comparison of nominal and actual values, is determined proportionally from the maximum value.

Claims

1. A process for regulating braking power in a braking operation of a supercharged internal combustion engine, an exhaust gas of which is backed-up by an actuator in an exhaust gas duct before entering an exhaust gas turbine of an exhaust gas turbine supercharger, the process comprising the acts of:

electronically storing a compressor performance graph of an air compressor of the turbine supercharger representing a relationship between a mass throughput and total pressure ratio for different exhaust gas turbo supercharger rotational speeds, said performance graph having nominal parameters for a large number of operating points and being used by an engine controller as input parameters for a comparison of nominal and actual values, wherein a plurality of operating lines for certain actuator positions and certain engine speeds, as well as for a constant turbine inlet pressure, are contained in the performance graph;

determining and setting a preferred actuator position from the performance graph by taking as a controlling parameter a corresponding turbine inlet pressure for different exhaust gas turbo supercharger rotational speeds, compressor mass flows, and compressor pressure ratios as a nominal value from the performance graph;

proportionally determining an actual value corresponding to the desired braking power from a maximum value of the turbine inlet pressure within operating limits of the exhaust gas turbocharger, said maximum value being inferred as a function of the engine speed from a characteristic rotational speed line stored in the performance graph.

2. The process according to claim 1, wherein the characteristic rotational speed line extends near a pump limit of the compressor in the performance graph.

3. The process according to claim 1, further comprising the act of recording engine operating lines for engine braking operation and fired-up operation in the performance graph.

4. The process according to claim 2, further comprising the act of recording engine operating lines for engine braking operation and fired-up operation in the performance graph.

5. The process according to claim 3, further comprising the act of supplying a braking signal of a braking signal transmitter to the engine controller to indicate a braking operation state of the internal combustion engine.

6. The process according to claim 4, further comprising the act of supplying a braking signal of a braking signal transmitter to the engine controller to indicate a braking operation state of the internal combustion engine.

7. The process according to claim 1, further comprising the act of triggering an additional engine braking device via the engine controller in the engine braking state.

8. The process according to claim 7, wherein the additional engine braking device comprises braking valves in a cylinder of the internal combustion engine.

9. The process according to claim 5, further comprising the act of generating a normalized braking signal via a braking signal transmitter as a function of an operating position of the braking signal transmitter;

and

using the normalized braking signal by the engine controller for an infinitely variable determination of the actual value of the turbine inlet pressure as a corresponding portion of the maximum value.

10. The process according to claim 6, further comprising the act of generating a normalized braking signal via a braking signal transmitter as a function of an operating position of the braking signal transmitter;

and

using the normalized braking signal by the engine controller for an infinitely variable determination of the actual value of the turbine inlet pressure as a corresponding portion of the maximum value.

11. The process according to claim 7, further comprising the act of generating a normalized braking signal via a braking signal transmitter as a function of an operating position of the braking signal transmitter;

and

using the normalized braking signal by the engine controller for an infinitely variable determination of the actual value of the turbine inlet pressure as a corresponding portion of the maximum value.

12. The process according to claim 8, further comprising the act of generating a normalized braking signal via a braking signal transmitter as a function of an operating position of the braking signal transmitter;

and

using the normalized braking signal by the engine controller for an infinitely variable determination of the actual value of the turbine inlet pressure as a corresponding portion of the maximum value.

13. The process according to claim 1, further comprising the act controlling the engine braking power via a guide baffle position of a variable turbine geometry of the exhaust gas turbine.

14. A software product for regulating braking power in a braking operation of a supercharged internal combustion engine, an exhaust gas of which is backed-up by an actuator in an exhaust gas duct before entering an exhaust gas turbine of a supercharger, comprising:

a computer readable medium having stored thereon program code segments that;

determine and set a preferred actuator position from a compressor performance graph electronically stored in a memory by taking as a controlling parameter a corresponding turbine inlet pressure value for different exhaust gas turbo supercharger rotational speeds, compressor mass flows, and compressor pressure ratios as a nominal value from the performance graph, said performance graph representing a relationship between a mass throughput and total pressure ratio for different rotational speeds, wherein a plurality of operating lines for certain actuator positions and certain engine speeds, as well as for a constant turbine inlet pressure, are contained in the performance graph;

proportionally determine an actual value corresponding to the desired braking power from a maximum value of the turbine inlet pressure within operating limits of the exhaust gas turbocharger, said maximum value being inferred as a function of the engine speed from a characteristic rotational speed line stored in the performance graph.