On-board diagnostics of a turbocharger system

Abstract

A turbocharger system (1) of a combustion engine (4) comprises a turbocharger turbine (5) operable by exhaust gases, a valve (7) configured to control gas flow of pressurized gas from a pressurized gas reservoir (6) to the turbocharger turbine (5), and a sensor (8). Turbocharger system operation comprises injecting a test pulse of pressurized gas from the pressurized gas reservoir (6) to drive the turbocharger turbine (5) by means of controlling the valve (7), detecting an impact of injected pressurized gas on the turbocharger turbine (5) by means of the sensor (8), collecting data from the sensor (8), and diagnosing the turbocharger system (1) by evaluating an operational response of the turbocharger turbine (5) as a result of the injected test pulse of pressurized gas, based on the collected data.

Claims

1. A method for on-board diagnostics of a turbocharger system for a vehicle, the turbocharger system being fluidly connected to an exhaust manifold of a combustion engine, wherein the turbocharger system comprises: a turbocharger turbine operable by exhaust gases from the exhaust manifold, a pressurized gas reservoir being fluidly connectable to the turbocharger turbine, a valve configured to control flow of pressurized gas from the pressurized gas reservoir to the turbocharger turbine, and a sensor, wherein the method comprises the steps of injecting a test pulse of pressurized gas from the pressurized gas reservoir to drive the turbocharger turbine by means of controlling the valve, measuring movement of the turbocharger turbine caused by the injected pressurized gas directly with the sensor, collecting data from the sensor, and evaluating an operational response of the turbocharger turbine as a result of the injected test pulse of pressurized gas, based on the collected data, wherein evaluating the operational response of the turbocharger turbine comprises the further step of determining that the evaluated operational response of the turbocharger turbine indicates no, by the sensor, measurable response of the turbocharger turbine as the result of the injected test pulse, injecting a further pulse of pressurized gas from the pressurized gas reservoir to drive the turbocharger turbine, wherein the further pulse is longer than the previous pulse, measuring movement of the turbocharger turbine caused by the injected pressurized gas directly with the sensor, and collecting data from the sensor, evaluating the operational response of the turbocharger turbine as a result of the injected further pulse of pressurized gas based on the collected data, wherein the further steps of the method are repeated until the evaluated operational response of the turbocharger turbine indicates, by the sensor measurable, response of the turbocharger turbine as the result of the injected further pulse.

2. A method according to claim 1, wherein the step of evaluating the operational response of the turbocharger turbine comprises the further step of comparing the data collected after the test pulse has been injected to data collected before the test pulse is injected.

3. A method according to claim 1, wherein the further step of determining a current delay time, wherein delay time is defined as the maximum time from activating the step of injecting the test pulse or further pulse to de-activating the step of injecting the test pulse or further pulse without measurable response.

4. A method according to claim 3, wherein the further steps of when a current delay time has been determined, injecting a control pulse of pressurized gas from the pressurized gas reservoir to drive the turbocharger turbine, wherein the control pulse is longer than the current delay time, measuring movement of the turbocharger turbine caused by the injected pressurized gas with the sensor, collecting data from the sensor, and evaluating if the operational response as a result of the injected control pulse indicates that the turbocharger system operates as expected.

5. A method according to claim 3, wherein the further step of storing current delay time as a stored system delay time, whereby stored system delay time is used to optimize operation of the turbocharger system.

6. A method according to claim 5, wherein the further step of correlating and storing the stored system delay time together with additional operating and/or environmental parameters.

7. A method according to claim 1, wherein each further pulse is between 0.05 and 0.15 seconds longer than the previous pulse.

8. A method according to claim 1, wherein the further step of collecting data regarding ambient temperature by means of an ambient temperature sensor, wherein if the ambient temperature is equal to or below 0 degrees Celsius, the method comprises the further step of determining that there is risk of freezing.

9. A method according to claim 8, wherein if it has been determined that there is risk of freezing the method comprises the further steps of injecting a test pulse being equal to or longer than a predicted turbocharger start-up pulse, and evaluating the operational response of the turbocharger turbine as a result of the injected test pulse, wherein if the there is no operational response the method comprises the further step of, determining that the turbocharger system is frozen.

10. A method according to claim 1, wherein the method for on-board diagnostics is performed when the combustion engine is in operation.

11. A method according to claim 1, wherein the method for on-board diagnostics is performed when the combustion engine is not in operation.

12. A method according to claim 1, wherein the test pulse is 0.01 to 0.3 seconds long.

13. A method according to claim 1, wherein the method steps are performed by a control unit.

14. A computer readable medium carrying a computer program comprising program code for performing the steps of claim 1 when said program code is run on a computer.

15. A control unit for controlling a method for on-board diagnostics, the control unit being configured to perform the steps of the method according to claim 1.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) With reference to the appended drawings, below follows a more detailed description of embodiments of the invention cited as examples.

(2) In the drawings:

(3) FIG. 1 shows a schematic side view of a vehicle comprising a combustion engine and an exemplary embodiment of a turbocharger system according to the invention,

(4) FIG. 2 shows a schematic view of a combustion engine comprising an exemplary embodiment of a turbocharger system according to the invention,

(5) FIG. 3 shows a flow chart disclosing the steps performed when executing an exemplary embodiment of a method for on-board diagnostics of a turbocharger system according to the invention,

(6) FIG. 4 shows a flow chart disclosing the steps performed when executing another exemplary embodiment of a method for on-board diagnostics of a turbocharger system according to the invention, and

(7) FIG. 5 shows a flow chart disclosing the steps performed when executing yet an exemplary embodiment of a method for on-board diagnostics of a turbocharger system according to the invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE INVENTION

(8) The following description of exemplary embodiments of the invention is presented only for purposes of illustration and should not be seen as limiting. The description is not intended to be exhaustive and modifications and variations are possible in the light of the above teachings, or may be acquired from practice of various alternative embodiments of the invention. The exemplary embodiments discussed herein were chosen and described in order to explain the principles and the nature of various embodiments and its practical application to enable one skilled in the art to utilize the exemplary embodiments in various manners, and with various modifications, as are suited to the particular use contemplated. It should be appreciated that the aspects presented herein separately may be practiced in any combination with each other unless otherwise explicitly is stated.

(9) Reoccurring reference signs refer to corresponding elements throughout the detailed description. When herein using reference signs indexed with a letter what is referred to is an exemplary embodiment of a feature that may be realized in different ways.

(10) FIG. 1 shows a schematic side view of a vehicle 2 comprising a combustion engine 4 and an exemplary embodiment of a turbocharger system 1 according to the invention. The combustion engine 4 comprises the turbocharger system 1, which in turn comprises a turbocharger 12, a pressurized gas reservoir 6, a valve 7 and a control unit 10. In FIG. 1 the control unit 10 comprises an on-board diagnostics unit 10a, i.e. the on-board diagnostics unit 10a is an integrated part or functionality of the control unit 10. The turbocharger 12 comprises a turbocharger turbine 5. The combustion engine 4 is fluidly connected to the turbocharger system 1 and to the turbocharger 12. The control unit 10 is configured to at least control the valve 7 which in turn controls the flow of pressurized gas from the pressurized gas reservoir 6 to the combustion engine 4.

(11) In addition to the components explicitly mentioned in relation to FIG. 1 the vehicle 2, the combustion engine 4 and the turbocharger system 1 obviously comprise a large number of additional components, of which the most important components for understanding the invention will be disclosed in relation to FIG. 2.

(12) FIG. 2 shows a schematic view of at least parts of a combustion engine 4 comprising an exemplary embodiment of a turbocharger system 1 according to the invention. The turbocharger system 1 is configured to be used together with the combustion engine 4. The turbocharger system 1 comprises a turbocharger turbine 5 and a turbocharger compressor 13. The turbocharger compressor 13 is fluidly connected to an inlet manifold 11 by means of an inlet manifold conduit 16 and to an air inlet 17 configured to receive outside air. The turbocharger turbine 5 is connected to the turbocharger compressor 13 by means of a turbine shaft 14. The turbocharger turbine 5 is configured to drive the turbocharger compressor 13 via the turbine shaft 14. The combustion engine has an exhaust manifold 3 and the turbocharger turbine 5 is fluidly connected to the exhaust manifold 3 by means of an exhaust manifold conduit 15. The turbocharger turbine 5 is operable by exhaust gases from the exhaust manifold 3. During operation of the combustion engine 4 the turbocharger 5 is driven by exhaust gases generated by fuel combustion. The turbocharger turbine 5 in turn drives the turbocharger compressor 13 via the turbine shaft 14, whereby the turbocharger compressor 13 may supply additional outside air from the air inlet 17 to the intake manifold 11 via the intake manifold conduit 16. By increasing the amount of air supplied to the combustion engine 4 even more fuel can be combusted whereby the combustion engine 4 can deliver more output power.

(13) The turbocharger system 1 further comprises a pressurized gas reservoir 6, being fluidly connectable to the turbocharger turbine 4, a valve 7, configured to control flow of pressurized gas from the pressurized gas reservoir 6 to the turbocharger turbine 5, at least one sensor 8 detecting impact of injected pressurized gas on the turbocharger turbine 5, and a control unit 10 arranged to control the valve 7. For the embodiment of the invention disclosed in FIG. 2 the control unit 10 comprises an on-board diagnostics unit 10a, i.e. the on-board diagnostics unit 10a is an integrated part or functionality of the control unit 10. In FIG. 2 the pressurized gas reservoir 6 is connected to the exhaust manifold 3 by means of a pressurized gas conduit 18. The pressurized gas reservoir 6 is also connected to a compressor 19 configured to supply pressurized gas to the pressurized gas reservoir 6. The compressor may be a compressor only used by the turbocharger system 1 or any other compressor or device of the vehicle 2 capable of providing pressurized gas.

(14) As shown in the exemplary embodiment of FIG. 2, the on-board diagnostics unit may be, but is not limited to be, a separate unit, but may very well be a separate functionality of the control unit. The control unit 10 may also control other components and functionalities of the combustion engine 4 and/or turbocharger system 1, such as e.g. the compressor 19, in addition to what explicitly is disclosed herein.

(15) According to the invention the pressurized gas reservoir 6 is connected to the exhaust manifold 3 or to the intake manifold 11. The intake manifold 11 is fluidly connected to the exhaust manifold 3 of the combustion engine 4. Pressurized gas from the pressurized gas reservoir 6 is injectable to the exhaust manifold 3 or to the intake manifold 11 of the combustion engine 4 during injection of a pulse. According to the exemplary embodiment of FIG. 2 the pressurized gas reservoir 6 is connected to the exhaust manifold 3. The sensor 8 is a sensor capable of detecting impact of injecting pressurized gas and may for example be a turbo speed sensor 8a and/or a boost pressure sensor 8c and/or an exhaust manifold pressure sensor 8b and/or a mass flow sensor 8d and/or an oxygen sensor 8e. When herein referring to sensor 8 also a combination of more than one sensor is considered to be an option. The sensor 8 may e.g. comprise a boost pressure sensor 8d and an oxygen sensor 8e. The exemplary positioning of the sensors 8 of FIG. 2 are not to be seen as limiting. As is apparent for a person skilled in the art, the respective sensor 8 may also be positioned differently.

(16) The control unit 10 is configured to control and perform the steps of any embodiment of the method according to the invention. Thereby the control unit 10 is configured to at least perform the steps of;

(17) inject a test pulse of pressurized gas from the pressurized gas reservoir 6 to drive the turbocharger turbine 5 by means of control of the valve 7,

(18) detect impact of injected pressurized gas on the turbocharger turbine 5 by means of the sensor 8,

(19) collect data from the sensor 8, and

(20) evaluate an operational response of the turbocharger turbine 5 as a result of the injected test pulse of pressurized gas, based on the collected data. Exemplary embodiments of methods according to the invention will be disclosed in relation to FIG. 3 to 5.

(21) In addition to the components explicitly mentioned in relation to FIG. 2 the combustion engine 4 and the turbocharger system 1 may obviously comprise a large number of additional components.

(22) The reference numerals of FIG. 1 and FIG. 3 will hereinafter also be used when discussing the exemplary embodiments of methods according to the invention disclosed in the flow charts of FIG. 3 to 5.

(23) FIG. 3 shows a flow chart disclosing the steps performed when executing an exemplary embodiment of a method for on-board diagnostics according to the invention. The different steps of the method are visualized by boxes in the flow chart. The method comprises the steps of:

(24) 100 injecting a test pulse of pressurized gas from the pressurized gas reservoir 6 to drive the turbocharger turbine 5 by means of controlling the valve 7,

(25) 110 detecting impact of injected pressurized gas on the turbocharger turbine 5 by means of the sensor 8,

(26) 120 collecting data from the sensor 8, and

(27) 130 evaluating an operational response of the turbocharger turbine 5 as a result of the injected test pulse of pressurized gas, based on the collected data.

(28) The method step of 100 injecting a test pulse is performed by means of 140 input of characteristics of a test pulse. According to exemplary embodiments of the invention the test pulse is 0.01 to 0.3 seconds long, preferably is 0.05 to 0.2 seconds long and more preferably is 0.1 second long. This is short pulses in relation to the pulses used during normal operation of the turbocharger system, i.e. when the system is used to improve turbocharger 12 response by means of pressurized gas. The method may be performed when the combustion engine 4 is in operation or when the combustion engine 4 is not in operation. The method steps are performed by means of a control unit 10.

(29) According to embodiments of the invention the step of 130 evaluating the operational response of the turbocharger turbine 5 may further comprise comparing the data collected after the test pulse has been injected to data collected before the test pulse is injected.

(30) By injecting a test pulse which is relatively short in comparison to the pulses used during normal operation of the turbocharger system 1, and collecting and evaluating data provided by such injection, it is possible to gain important information of the functionality of the system without wasting an excessive amount of compressed gas and without disturbing the driver more than necessary.

(31) FIG. 4 shows a flow chart disclosing the steps performed when executing another exemplary embodiment of a method for on-board diagnostics according to the invention. The different steps of the method are visualized by boxes in the flow chart. In addition to the method steps disclosed in relation to FIG. 3 the exemplary embodiment of FIG. 4 comprises the further step of:

(32) 150 assessing if the evaluated operational response of the turbocharger turbine 5 indicates no response of the turbocharger turbine 5 as the result of the injected test pulse.

(33) If the operational response of the turbocharger turbine 5 shows no response this may be an indication of that the injected test pulse was too short in order to provide a measurable response of the turbocharger turbine 5. Thereby it can be determined that in order for the turbocharger turbine 5 to respond the pulse needs to be longer or that the turbocharger system is not working properly. Thus, according to the exemplary embodiment if there is no response the method comprises the further steps of:

(34) 101 injecting a further pulse of pressurized gas from the pressurized gas reservoir 6 to drive the turbocharger turbine 5,

(35) 110 detecting impact of injected pressurized gas on the turbocharger turbine 5 by means of the sensor 8,

(36) 120 collecting data from the sensor 8, and

(37) 131 evaluating the operational response of the turbocharger turbine 5 as a result of the injected further pulse of pressurized gas based on the collected data,

(38) wherein the further steps of the method 101, 110, 120, 131, 150 are repeated until the method step of 131 evaluating the operational response indicates response of the turbocharger turbine 5 as the result of the injected further pulse. The method step of 101 injecting the further pulse is performed by means of 160 input of characteristics of a further pulse.

(39) By means of the method the shortest pulse possible providing turbocharger turbine 5 response can be used when testing the turbocharger system 1. As short pulse as possible is desirable since less pressurized gas is wasted. A long pulse is also more disturbing for the driver and requires the turbocharger 12 to speed down fully before next test pulse can be injected.

(40) According to further embodiments of the invention each further pulse is between 0.05 and 0.15 seconds longer than the previous pulse, preferably between 0.05 and 0.1 seconds longer and more preferably 0.05 seconds longer than the previous pulse. According to other embodiments of the invention the further pulses are successively longer than the previous pulse.

(41) According to embodiments of the invention, when the step of 131 evaluating an operational response of the turbocharger turbine 5 indicates response of the turbocharger turbine 5 the method may further comprise the step of:

(42) 151 determining a current delay time.

(43) Delay time is herein defined as the maximum time from activating the step of injecting the test pulse or further pulse to de-activating the step of injecting the test pulse or further pulse without measurable response, i.e. delay time is defined as the maximum pulse time without measurable response.

(44) Determining the delay time is advantageous since knowing the turbocharger system 1 delay time enables improved useability of the combustion engine 4 and the turbocharger system 1. By knowing the delay time the control unit 10 is capable of better assessing when and how pressurized gas should be injected, for example in order to fulfil engine output demands of the driver during acceleration. Thereby improved driveability of the vehicle 2 can be achieved. Thus, delay time is an important input parameter for the control unit 10.

(45) FIG. 5 shows a flow chart disclosing the steps performed when executing yet an exemplary embodiment of a method for on-board diagnostics according to the invention. The different steps of the method are visualized by boxes in the flow chart. The embodiment of a method according to FIG. 5 comprises the steps of:

(46) 100 injecting a test pulse of pressurized gas from the pressurized gas reservoir 6 to drive the turbocharger turbine 5 by means of controlling the valve 7,

(47) 110 detecting impact of injected pressurized gas on the turbocharger turbine 5 by means of the sensor 8,

(48) 120 collecting data from the sensor 8, and

(49) 130 evaluating an operational response of the turbocharger turbine 5 as a result of the injected test pulse of pressurized gas, based on the collected data.

(50) The method step of injecting a test pulse 100 is performed by means of 140 input of characteristics of the test pulse. The method further comprises the step of:

(51) 170 collecting data regarding ambient temperature by means of 180 input of ambient temperature, measured by means of an ambient temperature sensor.

(52) If the ambient temperature is equal to or below 0 degrees Celsius, the method further comprises the method step of:

(53) 190 determining that there is risk of freezing.

(54) In FIG. 5 the method step of collecting data regarding ambient temperature 170 is depicted as being performed in connection to the method step of 120 collecting data from the sensor 8 and the method step of 190 determining that there is risk of freezing is depicted as being performed in connection to the method step of 130 evaluating an operational response of the turbocharger turbine 5. This is however not to be seen as limiting for the invention. Both the method step of collecting data regarding ambient temperature 170 and the step of 190 determining that there is risk of freezing may be performed continuously, simultaneously as any other step of the method or at a different interval than the other steps of the method. The more often either of the method steps are performed the better is probably the prediction of that the system may be frozen.

(55) According to yet an embodiment of the present invention, if it has been determined that there is risk of freezing the method comprises the steps of:

(56) 102 injecting a test pulse being equal to or longer than a predicted turbocharger start-up pulse,

(57) 110 detecting impact of injected pressurized gas on the turbocharger turbine 5 by means of the sensor 8,

(58) 120 collecting data from the sensor 8, and

(59) 132 evaluating the operational response of the turbocharger turbine 5 as a result of the injected test pulse,

(60) wherein if the there is no operational response the method comprises the further comprises the step of;

(61) 210 determining that the turbocharger system 1 is frozen.

(62) The method step of 102 injecting a test pulse being equal to or longer than a predicted turbocharger start-up pulse is performed by means of 200 input of characteristics of a predicted turbocharger start-up pulse.

(63) By injecting a test pulse which with certainty is known to give turbocharger turbine 5 response it can be determined that if still no response is obtained something is wrong with the turbocharger system 1. If knowledge thereof coincides with knowledge of that there is risk of freezing of the turbocharger system 1 it can be determined that the system is frozen. Knowing that the system is frozen is important information in order for the control unit 10 to optimize usage of the turbocharger system 1. Activating the turbocharger system 1 when the system is frozen may damage components of the combustion engine 4 or turbocharger system 1 or may result in that a completely different transient response is obtained than what is expected which may affect as well driveability as safety.

(64) Although FIGS. 3 to 5 show a specific order of the method steps, the order of the steps may differ from what is depicted and various method steps may be performed simultaneously or partially simultaneously.

(65) When herein referring to a control unit what is considered is a device capable of performing calculations, executing methods and performing operations. The control unit may for example be a general-purpose processor, an application specific processor, a circuit containing processing components, a group of distributed processing components or a group of distributed computers devices. The control unit may be a part of a larger unit capable of controlling also other devices and functionalities. The control unit may be configured to control the devices and the functionalities explicitly stated herein, but is not limited to only controlling those devices and/or functionalities. In addition to the components and/or devices the control unit explicitly is connected to the control unit may also be connected to other components and/or devices.

(66) It is to be understood that the present invention is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims. Thus, variations to the disclosed embodiments can be understood and effected by the skilled addressee in practicing the claimed disclosure, from a study of the drawings, the disclosure, and the appended claims.