Method for controlling an inlet regulating mechanism of a turbocharger compressor

Abstract

The present invention relates to a method for controlling an inlet regulating mechanism of a turbocharger compressor. A method for controlling an inlet regulating mechanism in an air inlet of a compressor so as to switch the mechanism between an open position and a closed position for regulating the flow area of ​​the inlet. The method comprises an algorithm for determining when the inlet regulating mechanism is in a fault mode. According to the method, when an operating point on a compressor map is on the high flow side of a threshold line at which the inlet regulating mechanism switches from one position to another, a measured speed or pressure ratio is compared with a theoretical value of the speed or pressure ratio based on the compressor map for the open position of the mechanism. If the measured value differs from the theoretical value by more than a predetermined tolerance, a fault mode is indicated.

Description

Technical Field

[0001] The present disclosure relates to compressors, such as those used in turbochargers, and more particularly to compressors whose effective inlet area or diameter can be adjusted for different operating points. Background Art

[0002] An exhaust-driven turbocharger is a device used in conjunction with an internal combustion engine for increasing the power output of the engine by compressing air delivered to the intake of the engine to be mixed with fuel and burned in the engine. A turbocharger includes a compressor wheel mounted on one end of a shaft in a compressor housing and a turbine wheel mounted on the other end of the shaft in a turbine housing. Typically, the turbine housing is formed separately from the compressor housing, and there is another center housing connected between the turbine housing and the compressor housing to accommodate the bearings of the shaft. The turbine housing defines a generally annular chamber that surrounds the turbine wheel and receives exhaust gas from the engine. The turbine assembly includes a nozzle leading from the chamber to the turbine wheel. Exhaust gas flows from the chamber through the nozzle to the turbine wheel, and the turbine wheel is driven by the exhaust gas. Thus, the turbine extracts power from the exhaust gas and drives the compressor. The compressor receives ambient air through the inlet of the compressor housing, and the air is compressed by the compressor wheel and then discharged from the housing to the engine intake.

[0003] Turbochargers typically employ a centrifugal (also called "radial") type compressor impeller because centrifugal compressors can achieve relatively high pressure ratios in a compact arrangement. Intake air for the compressor is received in a generally axial direction at the inducer portion of the centrifugal compressor impeller and is discharged in a generally radial direction at the outlet inducer portion of the impeller. The compressed air from the impeller is delivered to the volute, and the air is supplied from the volute to the intake of the internal combustion engine.

[0004] The operating range of the compressor is an important aspect of the overall performance of the turbocharger. The operating range is usually defined by the surge line and the choke line on the compressor's operating diagram. The compressor diagram is usually expressed as the pressure ratio PR (discharge pressure P) on the vertical axis. out Divide by the inlet pressure P in ) versus the corrected mass flow on the horizontal axis. The choke line on the compressor diagram is located at high flows and represents the locus of points of maximum mass flow over the range of pressure ratios; that is, for a given point on the choke line, it is not possible to increase the flow while maintaining the same pressure ratio because a choking condition occurs in the compressor.

[0005] The surge line is located at low flows and represents the locus of the minimum mass flow points over the range of pressure ratios at which there is no surge; that is, for a given point on the surge line, decreasing the flow without changing the pressure ratio or increasing the pressure ratio without changing the flow will cause surge to occur. Surge is a flow instability that typically occurs when the compressor blade incidence angle becomes so large that significant flow separation occurs over the compressor blades. Pressure fluctuations and flow reversals may occur during surge.

[0006] In turbochargers for internal combustion engines, compressor surge can occur when the engine is running at high load or torque and low engine speed, or when the engine is running at low speed and there is a high level of exhaust gas recirculation (EGR). Surge can also occur when the engine is suddenly decelerated from a high speed. Extending the compressor's surge-free operating range for lower flows is a frequently sought goal in compressor design.

[0007] One solution for moving the surge line of a centrifugal compressor to the left (i.e., delaying surge to lower flows at a given pressure ratio) and moving the choke line to the right (i.e., increasing choke to higher flows at a given pressure ratio) is to employ an inlet adjustment mechanism in the compressor inlet. The applicant is the owner of co-pending applications that disclose various inlet adjustment mechanisms of this type, see, for example, Application Nos. 14 / 537,339; 14 / 532,278; 14 / 642,825; 14 / 573,603; and 14 / 551,218; the entire disclosures of which are incorporated herein by reference.

[0008] The present disclosure relates to a method for controlling such an inlet regulating mechanism. Summary of the invention

[0009] The present disclosure describes a method for use with an inlet adjustment mechanism in an air inlet of a compressor. The method includes a failure mode detection algorithm for determining when the inlet adjustment mechanism may not function properly. According to one embodiment, the method includes the following steps:

[0010] identifying a threshold line for a given relationship between a compressor pressure ratio PR, a flow rate W, and a turbocharger speed N on a compressor map, the threshold line being a line at which the inlet regulating mechanism switches between an open position and a closed position when an operating point of the compressor on the compressor map reaches the threshold line;

[0011] Determine the measured compressor flow W for the current operating point of the turbocharger and the engine m , measured compressor pressure ratio PR m , and the measured turbocharger speed N m and the measured engine speed Ne m one of the;

[0012] Determine characteristic compressor performance parameters for the current operating point The theoretical value of is one of the pressure ratio PR and the turbocharger speed N, and where The theoretical value of is the first compressor map MAP of the relationship between a given flow rate W, a pressure ratio PR, and one of a turbocharger speed N and an engine speed Ne when the inlet regulating mechanism is opened. O Export;

[0013] determining whether the current operating point is on the high flow side of the threshold line or on the low flow side of the threshold line; and

[0014] When it is determined that the current operating point is on the high flow side of the threshold line, where the desired state of the inlet regulating mechanism is open, if The measured value of If the difference between the theoretical value of and the inlet regulating mechanism exceeds a predetermined tolerance, it is determined that the inlet regulating mechanism is in a failure mode.

[0015] When it is determined that the current operating point is on the low flow side of the threshold line, where the desired state of the inlet regulating mechanism is closed, the method includes the step of checking for flow instability at the compressor inlet. The instability check may be performed using a flow meter and checking for instability in the measured flow, or alternatively using a pressure sensor and checking for instability in the measured pressure at the compressor inlet; another alternative is using a temperature sensor and checking for instability in the measured temperature at the compressor inlet. If flow instability is detected, the compressor map MAP is closed from the open O , the measured compressor pressure ratio PR m The flow rate W during surge is derived from S-O , and if W m With W S-O A difference less than a predetermined tolerance indicates that surge may be imminent.

[0016] In some embodiments, the method includes the step of taking action to prevent an overspeed condition of the turbocharger when operating conditions on the high flow side of the threshold line indicate a fault mode.

[0017] In some embodiments, the method includes the step of taking action to prevent surge of the compressor when the operating point is too close to a surge line for an open position of the inlet regulating mechanism.

[0018] In some embodiments, the compressor performance parameter is the turbocharger speed N. In this case, the turbocharger speed N will be measured m and the theoretical turbocharger speed N derived from the diagram of the opening position of the inlet regulating mechanismO If the measured speed differs from the theoretical value by more than a predetermined tolerance, a failure mode (or malfunction) of the mechanism is indicated.

[0019] In other embodiments, the performance parameter is the compressor pressure ratio PR. In this case, the measured pressure ratio PR m Compared with the theoretical value PR derived from the diagram in the open position O If the measured value differs from the theoretical value by more than a predetermined tolerance, a failure mode is indicated. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Having generally described the invention, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and in which:

[0021] Figure 1 is a schematic diagram of a compressor having an inlet regulating mechanism, wherein the inlet regulating mechanism is in a closed position;

[0022] Figure 2 Similar to Figure 1 , but showing the inlet adjustment mechanism in an open position;

[0023] Figure 3 A compressor diagram is schematically depicted, wherein the inlet regulating mechanism is in a position corresponding to Figure 1 The closed position of

[0024] Figure 4 A compressor diagram is schematically depicted, wherein the inlet regulating mechanism is in a position corresponding to Figure 2 The open position;

[0025] Figure 5 depicts a compressor map according to one embodiment of the present invention, on which a threshold line for switching an inlet regulating mechanism between its open and closed positions is identified, and an operating point on the high flow side of the threshold line at which the inlet regulating mechanism should normally be open is shown;

[0026] Figure 6 For Figure 5 The same compressor diagram, but showing the operating point on the low flow side of the threshold line where the inlet regulating mechanism should normally close;

[0027] Figure 7 is a schematic diagram of an engine control unit (ECU) in communication with an actuator that actuates an inlet regulating mechanism to move between an open position and a closed position;

[0028] Figure 8 A flowchart illustrating a method according to an embodiment of the present invention; and

[0029] Fig. 9 For similar Figure 8 A flow chart showing a method according to another embodiment of the present invention. DETAILED DESCRIPTION

[0030] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, these inventions may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. Like reference numerals refer to like elements throughout.

[0031] exist Figure 1 and Figure 2 , a compressor 10 to which a method according to an embodiment of the present invention may be applied is shown in cross-sectional view. The compressor 10 includes a compressor housing 12, which defines an air inlet 14 extending in the axial direction of the compressor. A compressor impeller 15 is disposed in the compressor housing and fixed to one end of a shaft 18, the compressor impeller 15 including a hub 16, a plurality of blades 20 extending generally radially outward from the hub 16, and the shaft 18 is rotatably driven in a suitable manner (e.g., by an exhaust-driven turbine, not shown) for rotatably driving the compressor impeller 15. The compressor housing defines a diffuser 22 for receiving and diffusing air, which is compressed as it passes through the compressor impeller. The diffuser delivers the diffused compressed air to a volute 24 defined by the compressor housing.

[0032] The compressor of the turbocharger comprises an inlet regulating mechanism 30 which is arranged in the air inlet 14 of the compressor housing and which can be in a closed position ( Figure 1 ) and the open position ( Figure 2 ). Movement of the mechanism 30 may entail axial sliding, pivoting, or helical (screw-type) movement of the mechanism, to name a few non-limiting examples. The details of the structure and operation of the inlet adjustment mechanism 30 are not relevant to the present disclosure, and any mechanism that operates to effectively change the flow area of ​​the air inlet 14 to the compressor impeller 15 may be employed in the practice of the present invention.

[0033] The inlet adjustment mechanism 30 is capable of adjusting the effective size or diameter of the inlet into the compressor impeller 15. Figure 2 As shown in FIG, when the inlet adjustment mechanism is in the open position, Figure 1 Compared with the effective diameter in the closed position of the compressor, the effective diameter of the inlet into the compressor impeller is relatively increased. In order to achieve this effect, the axial spacing distance from the mechanism 30 to the compressor impeller must be as small as possible.

[0034] At medium and high flow rates, the inlet adjustment mechanism 30 can be as follows Figure 2This can have the effect of increasing the effective inlet diameter and therefore reducing the flow velocity entering the compressor impeller. Figure 4 The diagram shows the Figure 2 The diagram shows the compressor pressure ratio PR (discharge pressure divided by inlet pressure) versus the corrected flow rate W. C (e.g., mass flow rate corrected to standard temperature and pressure inlet conditions). The diagram consists of a series of isokinetic lines N1 open 、N2 open 、N3 open 、N4 open and N5 open , on each constant velocity line, the compressor speed is held constant while the corrected flow and pressure ratio change. The plot includes a surge line in the open position, which is the locus of the point at which the compressor is about to surge; that is, if the flow is reduced at the same pressure ratio, or the pressure ratio is increased at the same flow, the compressor will experience surge.

[0035] At low flow rates, the inlet adjustment mechanism 30 can be placed Figure 1 This can have the effect of reducing the effective inlet diameter and therefore increasing the flow velocity entering the compressor impeller. The result is a reduction in the compressor blade incidence angle, effectively stabilizing the flow (i.e., making blade stall and compressor surge less likely). In other words, the compressor surge line will shift to lower flows (to the left on a plot of compressor pressure ratio versus flow). This Figure 3 The closed position diagram has the same speed line values. That is, N1 closed The value is equal to N1 open The same is true for other speeds.

[0036] Figure 3 and 4 The compressor map may be based on test data of a compressor operating with the inlet regulating mechanism in the closed position and the open position, respectively. Alternatively, the compressor map may be based on model predicted data of a compressor with the inlet regulating mechanism in the closed position and the open position, respectively.

[0037] Figure 5 For superposition Figure 1 The velocity line of the closed position and Figure 2 It can be seen that for a given compressor speed, the corresponding closed position and open position speed lines are Figure 5This means that at the pressure ratio and corrected flow conditions where the velocity lines intersect, the inlet regulating mechanism can be switched from one of its two positions to the other without any significant effect on the flow and pressure ratio of the compressor.

[0038] This characteristic velocity line crossing feature can be used to advantage when designing a control scheme for controlling the operation of the inlet regulating mechanism. Figure 5 By establishing a "best fit" "threshold" line TL representing the intersection of the speed lines on the superimposed graph in FIG. 1 , the operation of the inlet regulating mechanism can be regulated with reference to where on the compressor map the compressor is operating, and in particular where the operating point is located relative to the threshold line. Figure 5 When operating in the region to the left of the threshold line TL (referred to as the low flow side of the threshold line), the inlet adjustment mechanism may be placed Figure 1 When the compressor is operating to the right of the threshold line, in the region indicated as the high flow side of the threshold line, the inlet regulating mechanism may be placed in the closed position. Figure 2 When the operating point moves so as to cross the threshold line, by switching between the closed position and the open position, the transition from one position to the other does not cause any sudden change in the compressor flow and pressure ratio.

[0039] Implementation of the control scheme described above may be accomplished in various ways. Figure 7 The figure shows the general structure of a system for controlling an inlet adjustment mechanism 30. An actuator 26 of a suitable type is coupled to the inlet adjustment mechanism. The actuator may operate on any of a variety of principles; for example, the actuator may employ an electric motor, a pneumatic device, a hydraulic device, etc., for imparting motion to the inlet adjustment mechanism to move it between its closed position and its open position. The actuator 26 communicates with a control unit 40. The control unit includes a processor 50 (such as a microprocessor), a memory 60 (such as a non-volatile ROM, PROM, EPROM or EEPROM memory), and an interface 70 for communicating with other devices in the system. The memory may be programmed with control instructions (e.g., in hardware and / or firmware and / or software) that are executed by the processor for performing the functions of the control unit.

[0040] In one embodiment, the engine includes an engine control unit or ECU, such as those found on vehicles such as cars and trucks. An ECU is an electronic control unit that may include hardware and / or software components configured to control various aspects of the operation of the engine. In particular, the ECU may receive inputs from various engine sensors and turbocharger sensors and control various engine and turbocharger actuators. Engine sensors may be provided at various points in the engine to measure or otherwise determine corresponding engine parameters. Examples of engine sensors may include a throttle position sensor, an air temperature sensor, an engine revolutions per minute (RPM) sensor, an engine load sensor, an accelerator pedal position sensor, and / or other sensors. Engine actuators may include various relays, solenoids, ignition coils, or other electrically operated devices that may be used to control corresponding engine parameters. Turbocharger sensors may include sensors for measuring turbocharger speed, compressor inlet pressure, compressor discharge pressure, compressor correction flow, and other parameters.

[0041] In such Figure 7 In the exemplary embodiment shown, the ECU 40 may include an anti-surge control module for adjusting the position of the inlet regulating mechanism 30. The anti-surge control module may be any device, such as a device or circuit implemented in hardware, software, or a combination of hardware and software, which is configured to perform the corresponding functions of the anti-surge control module as described herein. In some embodiments, the anti-surge control module may be configured to enhance the ECU's ability to anti-surge and take or direct actions regarding anti-surge activities (e.g., via the actuator 26 that controls the inlet regulating mechanism 30) by identifying engine conditions for which actions are to be taken regarding anti-surge activities. Therefore, in an exemplary embodiment, the anti-surge control module may simply provide additional functionality to the ECU 40. However, in some embodiments, the anti-surge control module may be a unit separate from the ECU (i.e., Figure 6 The control unit 40 shown in FIG. 4 may not include an ECU but may communicate with the ECU).

[0042] The memory device 60 may include, for example, volatile and / or non-volatile memory. The memory device 60 may be configured to store information, data, applications, modules, instructions, etc., so that the device can perform various functions according to exemplary embodiments of the present invention. For example, the memory device 60 may be configured to buffer input data for processing by the processor 50. Additionally or alternatively, the memory device 60 may be configured to store instructions corresponding to the application for execution by the processor 50.

[0043] The processor 50 may be a processor of an ECU or a coprocessor or processor of a separate anti-surge control module. The processor 50 may be implemented in a variety of different ways. For example, the processor 50 may be implemented as a processing element, a coprocessor, a controller, or various other processing devices or apparatuses including integrated circuits such as, for example, ASICs (Application Specific Integrated Circuits), FPGAs (Field Programmable Gate Arrays), hardware accelerators, and the like. In an exemplary embodiment, the processor 50 may be configured to execute instructions stored in a memory device 60 or otherwise accessible to the processor 50. Therefore, whether configured by hardware or software methods or by a combination thereof, the processor 50 may represent an entity capable of performing operations according to an embodiment of the present invention while being configured accordingly. Therefore, for example, when the processor 50 is implemented as an ASIC, FPGA, and the like, the processor 50 may be a specially configured hardware for performing the operations described herein. Alternatively, as another example, when the processor 50 is implemented as an executor of software instructions, the instructions may specifically configure the processor 50, otherwise if not for a specific configuration provided by the instructions, the processor 50 may be a general processing element to perform the algorithms and / or operations described herein. However, in some cases, the processor 50 may be a processor of a specific device (eg, an ECU) adapted to further configure the processor 50 via instructions for executing the algorithms and / or operations described herein to employ embodiments of the present invention (eg, by adding an anti-surge control module).

[0044] The memory 60 of the control unit stores a first compressor map, such as corresponding to Figure 3 FIG. 10 shows an open position of the inlet regulating mechanism shown in FIG. 10 , and a second compressor diagram, such as corresponding to FIG. Figure 4The diagram of the closed position of the inlet regulating mechanism shown. The diagram can be stored in various forms, such as a lookup table, which includes variables of flow W versus pressure ratio PR along a series of constant speed lines N1, N2, N3, etc. The speed can be the turbocharger speed Nt, or alternatively, it can be the engine speed Ne. The memory also stores a threshold line TL, which represents a curve fit of the intersection of the speed lines derived in the aforementioned manner. The threshold line can be stored in various forms, such as a PR versus W table or a polynomial representing PR as a function of W. Alternatively, the threshold line can be represented by flow W versus engine speed Ne. The processor 50 receives inputs of compressor flow W, engine speed Ne, and compressor pressure ratio PR. The flow, engine speed, and pressure ratio are continuously sensed by appropriate sensors, and the sensed values ​​are sent to the processor (for example, at regular time step intervals, such as every 0.1 second or other appropriately selected intervals). Additional parameters can be sensed and sent to the processor for controlling the inlet regulating mechanism, including but not limited to the time rate of change of engine speed ΔNe / Δt (or alternatively, the time rate of change of turbocharger speed ΔNt / Δt). As described further below, the processor uses these sensed parameters to control the inlet regulating mechanism and detect failure modes of the inlet regulating mechanism.

[0045] The method for controlling an inlet regulating mechanism may be performed in accordance with co-pending U.S. application No. 15 / 925,713 filed by the present applicant on March 19, 2018, the entire disclosure of which is incorporated herein by reference. Although the method is effective for switching the inlet regulating mechanism between its open position and closed position at or near the threshold line TL, there is still the possibility that the mechanism may not switch as instructed. Various circumstances may cause such a failure, such as mechanical failure of an actuator for the inlet regulating mechanism, mechanical failure of the mechanism itself, binding of the mechanism due to abnormal conditions within the mechanism, etc. In any case, the inability of the mechanism to switch to the commanded position may have potentially serious consequences. For example, when the operating point OP is such as Figure 6 When the inlet regulating mechanism is on the low flow side of the threshold line as in the diagram, the inlet regulating mechanism should be closed to move the surge line to the left on the diagram. If a fault causes the mechanism to remain in the open position, it increases the likelihood that the compressor will experience surge, which may damage the compressor.

[0046] On the other hand, when the operating point OP is Figure 5 When the inlet regulating mechanism is on the high flow side of the threshold line as in Figure 1, the inlet regulating mechanism should be open. If a fault causes the mechanism to remain closed, the possibility of the compressor experiencing an overspeed condition is increased, which may cause damage to various components of the turbocharger.

[0047] The object of the present invention is to detect a failure mode of an inlet regulating mechanism, i.e. to detect whether the mechanism is open when it should be closed, or whether the mechanism is closed when it should be open, so that appropriate measures can be taken to avoid compressor surge or overspeed. The method according to an embodiment of the present invention is advantageous because its implementation is simple and does not require additional sensing parameters beyond those already required for controlling the inlet regulating mechanism.

[0048] Now first refer to Figure 5 Describe the method, Figure 5 A compressor map and a current operating point OP in the high flow region of the map are shown, in which the inlet regulating mechanism should be open. In order to implement the method, the control unit must have access to a first compressor map applicable when the inlet regulating mechanism is open and optionally to a second compressor map applicable when the inlet regulating mechanism is closed. Figure 5 , speed lines from both diagrams are shown. For simplicity and clarity of the method, the operating point OP has been chosen so that it falls exactly on the speed line N5 shown with a square symbol of the first (open mechanism) diagram. Of course, this diagram is the correct diagram for the compressor if it is assumed that the inlet regulating mechanism is actually in the (correct) open position. In fact, if the mechanism is open, the actual measured speed N at the operating point is m should correspond to the predicted (or theoretical) speed value of the diagram for N5, as can be seen by comparing its position with the N5 speed line of the open mechanism diagram. Accordingly, if the operating point is located on the diagram based on speed N and flow W, the measured compressor pressure ratio PR m should correspond to the predicted (or theoretical) pressure ratio from the diagram.

[0049] The method according to the present invention requires (1) determining characteristic compressor performance parameters of the current operating point The theoretical value of is one of PR and N, and The theoretical value is when the inlet regulating mechanism is opened from the first compressor map MAP given the relationship between W, PR and N O (2) determining whether the current operating point is on the high flow side of the threshold line or on the low flow side of the threshold line; (3) when it is determined that the current operating point is on the high flow side of the threshold line where the desired state of the inlet regulating mechanism is open, if The measured value of If the theoretical value of the inlet regulating mechanism differs by more than a predetermined tolerance, it is determined that the inlet regulating mechanism is in a fault mode.

[0050] exist Figure 5 In the example shown, in which the turbocharger speed N is used as the characteristic performance parameter, when the operating point is on the high flow side of the threshold line TL, the actual measured speed N is determined. mand compare it with the theoretical speed N derived from the first opening mechanism diagram O If the actual speed is N O If the pressure is within an acceptable small tolerance of , the mechanism should be open and therefore no fault condition exists. Figure 5 If the actual speed N is measured m If the measured speed is equal to N5 or within an acceptable tolerance of N5, then the mechanism is functioning properly and no measures are required to avoid overspeeding. On the other hand, if the assumed measured speed differs from N5 by more than the tolerance, then there is a malfunction and measures to avoid overspeeding may be required.

[0051] Reference now Figure 6 , the operating point OP is located on the low flow side of the threshold line. In the low flow area, the inlet regulating mechanism should be closed. In one embodiment of the present invention, the same speed checking strategy used in the high flow area can also be used in the low flow area. Therefore, the measured actual speed N m MAP from the closed organization diagram CL Theoretical speed N CL compare, and if N m In N CL If N is within the predetermined tolerance, the mechanism is operating normally and no fault condition exists. m Open the Institutional Map from O Theoretical speed N O Compare and O within a predetermined tolerance, it indicates that the mechanism is actually open and a fault condition exists.

[0052] In such Figure 6 In another embodiment of the invention shown, a simpler algorithm is used. A flow meter is used to measure the flow at the compressor inlet, or alternatively, a pressure sensor or temperature sensor is used to measure the pressure or temperature in the inlet. If no instability is detected, normal operation is indicated. If there is an instability in the measured flow or pressure or temperature, it indicates that surge may be imminent. For verification, the measured compressor flow W m Compared with the flow existing at the surge line of the open mechanism diagram (at the same pressure ratio PR), the flow is denoted as W S-O If the flow difference is less than the predetermined tolerance, this indicates that there may be a risk of compressor surge, because if the inlet regulating mechanism fails and opens, the operating point OP is close to the surge line. Therefore, measures can be taken to avoid surge.

[0053] Figure 8A flow chart of a method according to an embodiment of the invention is depicted, which is applicable to a system where there is a speed sensor on the turbocharger for detecting the turbocharger speed N. The steps shown in the flow chart are repeatedly performed in a series of time steps, and the time interval between the cycles is selected to be appropriately small so that the controller can adjust the inlet regulation mechanism and the transient behavior of the compressor. At step 100, the compressor flow W at the current time step (i.e., the current operating point OP of the compressor) is determined by a suitable sensor. m , compressor pressure ratio PR m and turbocharger speed N m The measured value of is obtained and provided to the control unit. At the subsequent step 102, it is asked whether the current operating point is on the high flow side of the threshold line. If the answer is "yes", the desired position of the inlet regulating mechanism is open. Therefore, at the subsequent step 104, the opening mechanism map MAP is used. O Derived at the measured flow rate W m and the measured pressure ratio PR m Theoretical turbocharger speed N at O At step 106, it is asked whether the measured speed is within the tolerance of the theoretical open position speed, or in sign, whether |N O -N m |≤k0 (where k0 is a tolerance value). If the answer is "yes", it means that the inlet regulating mechanism is open, indicating normal operation as shown in block 114, so no action is taken and the routine returns to step 102 for the next cycle.

[0054] If the answer to step 106 is “no”, then it indicates that there is something abnormal with the inlet regulating mechanism which may increase the likelihood of a compressor overspeed condition, so action is taken at step 118 to prevent overspeed and the routine returns to step 100 .

[0055] At query step 102, if the operating point is not on the high flow side of threshold line TL, then, as previously described, flow instability at the compressor inlet is checked at step 108. If no flow instability is detected, then no surge risk is indicated (normal operation as indicated at 114), and the routine returns to step 100. If flow instability is detected, then at a subsequent step 110, the measured pressure ratio PR m MAP for the open position of the inlet adjustment mechanism O Derived flow W at the surge line of the opening mechanism diagram S-O At step 112, it is inquired whether the measured flow rate differs from the surge flow rate by less than a predetermined tolerance, or in symbolic representation, whether |W m -W S-O|≤k1*W S-O (where k1 is the tolerance value). If the answer is "no", it means normal operation (low risk of surge) as shown in box 114, so no action is taken and the routine returns to step 100 for the next loop. If the answer at step 112 is "yes", then it indicates a risk of a compressor surge condition, so action is taken at step 116 to prevent surge, and the routine returns to step 100.

[0056] The tolerance values ​​k0 and k1 are appropriately selected to provide a reliable indication of the normal function or dysfunction of the inlet regulating mechanism and to minimize the risk of surge. In order to minimize the occurrence of false indications of dysfunction in high flow areas where the compressor is in danger of overspeed, a smaller value of the tolerance value k0 is usually used, but if it is too small, real dysfunction events may be missed. Therefore, the tolerance value k0 is selected to strike a balance between these two considerations. In order to minimize the risk of compressor surge in low flow areas, a larger value of k1 is usually used, but if this value is too large, the strategy will be too conservative and measures to avoid surge may be taken when the compressor is not actually in danger of surge. If the value of k1 is too small, the risk of surge occurring increases. Therefore, the value of k1 is selected so as to strike an appropriate balance between these considerations.

[0057] Fig. 9 1 is a flow chart illustrating a method according to another embodiment of the present invention, which is applicable to the case where there is no turbocharger speed sensor. Figure 8 The method is similar to that of FIG. 2 , but instead uses the turbocharger speed N as the characteristic compressor performance parameter, which is compared with the theoretical map value when the operating point is on the high flow side of the threshold line, using the compressor pressure ratio PR instead. In step 200 , the compressor flow W for the current operating point OP of the compressor is determined by a suitable sensor. m , compressor pressure ratio PR m and engine speed Ne m The measured values ​​are then made available to the control unit.

[0058] At the following step 202, it is asked whether the current operating point is on the high flow side of the threshold line. If the answer is "yes", the desired position of the inlet regulating mechanism is open. Therefore, at the following step 204, the opening mechanism map MAP is used. O Derived measured flow rate W m and the measured engine speed Ne m Theoretical pressure ratio PR O At step 206, it is inquired whether the measured pressure ratio is within the tolerance of the theoretical open position value, or in symbolic terms, whether |PR O –PRm |≤k2 (where k2 is a tolerance value). If the answer is "yes", it means that the inlet regulating mechanism is open, indicating normal operation as shown in block 214, so no action is taken and the routine returns to step 200 for the next cycle.

[0059] If the answer at step 206 is “no”, then it indicates that there is an anomaly somewhere with the inlet regulating mechanism which may increase the likelihood of a compressor overspeed condition, so action is taken at step 218 to prevent overspeed and the routine returns to step 200 .

[0060] At query step 202, if the operating point is not on the high flow side of threshold line TL, then at subsequent step 208, flow instability in the compressor inlet is checked. If no instability is detected, normal operation is indicated as described at 114, and the routine returns to step 200. If flow instability is detected, then at step 210, the measured pressure ratio PR m MAP for the open position of the inlet adjustment mechanism O Derived flow W at the surge line of the opening mechanism diagram S-O At step 212, it is inquired whether the measured flow rate differs from the surge flow rate by less than a predetermined tolerance, or in symbolic representation, whether |W m -W S-O |≤k1*W S-O If the answer is "no", it means that there is normal operation (low risk of surge) as shown in box 214, so no action is taken and the routine returns to step 200 for the next loop. If the answer at step 212 is "yes", it indicates a risk of compressor surge condition, so at step 216, action is taken to prevent surge and the routine returns to step 200.

[0061] At a given flow rate, N at low PR OP and N CL The difference between is significantly smaller than that at high PR. Therefore, in some embodiments of the present invention, it may be advantageous for one or more of the tolerance values ​​k0, k1 and k2 to be a function of the pressure ratio PR. Thus, for example, k0 may be relatively small at low pressure ratios and relatively large at high pressure ratios, and the same is true for k1 and / or k2.

[0062] Many modifications and other embodiments of the inventions described herein will occur to those skilled in the art having the benefit of the teachings presented in the foregoing description and the associated drawings. Therefore, it will be understood that the invention is not limited to the specific embodiments disclosed, and modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A fault detection method for a compressor inlet regulating mechanism, the compressor inlet regulating mechanism being arranged in an air inlet of a compressor of a turbocharger for increasing an intake pressure of an internal combustion engine, the inlet regulating mechanism being actuatable to switch between a closed position for reducing a flow area of ​​the air inlet and an open position for increasing a flow area of ​​the air inlet, the method comprising: identifying a threshold line for a relationship between a given compressor pressure ratio (PR), a flow rate (W), and one of a turbocharger speed (N) and an engine speed (Ne) on a compressor map, the threshold line being a line at which the inlet regulating mechanism switches between the open position and the closed position when an operating point of the compressor on the compressor map reaches the threshold line; Determine the measured compressor flow (W) for the current operating point of the turbocharger and engine m ), measured compressor pressure ratio (PR m ), and the measured turbocharger speed (N m ) and the measured engine speed (Ne m )one; Determine characteristic compressor performance parameters for the current operating point The theoretical value of is one of the compressor pressure ratio (PR) and the turbocharger speed (N), and where The theoretical value of is when the inlet regulating mechanism is opened, from a first compressor map (MAP) of the relationship between a given flow (W), a pressure ratio (PR), and one of a turbocharger speed (N) and an engine speed (Ne) O ) export; determining whether the current operating point is on the high flow side of the threshold line or on the low flow side of the threshold line; as well as When it is determined that the current operating point is on the high flow side of the desired state of the inlet regulating mechanism of the threshold line, if The measured value of If the difference between the theoretical value of and the inlet regulating mechanism exceeds a predetermined tolerance, it is determined that the inlet regulating mechanism is in a failure mode.

2. The method according to claim 1, further comprising: When it is determined that the current operating point is on the closed low flow side of the desired state of the inlet regulating mechanism of the threshold line, checking for flow instability in the air inlet of the compressor and, if flow instability is detected, adjusting the compressor pressure ratio (PR) from the first compressor map (MAP) at the measured compressor pressure ratio (PR) O ) Determine the flow rate during surge (W S-O ), and if the measured compressor flow (W m ) and the determined surge flow rate (W S-O ) differs by less than a predetermined tolerance, it is determined that surge may be about to occur.

3. The method according to claim 1, further comprising: When the inlet regulating mechanism is in a fault mode, action is taken to prevent an overspeed condition of the turbocharger.

4. The method according to claim 2, further comprising: When surge may be imminent, measures are taken to prevent the compressor from surging.

5. The method according to claim 1, wherein: The characteristic compressor performance parameters is the turbocharger speed (N).

6. The method according to claim 1, wherein: The characteristic compressor performance parameters is the compressor pressure ratio (PR).

7. A computer program product, comprising at least one computer-readable storage medium having computer-executable program code instructions stored therein, the computer-executable program code instructions being used to control a compressor inlet regulating mechanism disposed in an air inlet of a centrifugal compressor of a turbocharger for increasing an intake pressure of an internal combustion engine, the inlet regulating mechanism being actuatable to switch between a closed position for reducing a flow area of ​​the air inlet and an open position for increasing a flow area of ​​the air inlet, the compressor having a compressor map of a correlation between a given flow rate (W), a compressor pressure ratio (PR), and one of a turbocharger speed (N) and an engine speed (Ne), the compressor map including a threshold line at which the inlet regulating mechanism is to switch between the open position and the closed position, the computer-executable program code instructions comprising: The measured compressor flow (W) for the current operating point of the turbocharger and the engine is used to determine m ), the measured compressor pressure ratio (PR), and the measured turbocharger speed (N m ) and the measured engine speed (Ne m ) is a program code instruction; Characteristic compressor performance parameters for determining the current operating point The theoretical value of the program code instructions, where is one of the compressor pressure ratio (PR) and the turbocharger speed (N), and where The theoretical value of is when the inlet regulating mechanism is opened, from a first compressor map (MAP) of the relationship between a given flow (W), a pressure ratio (PR), and one of a turbocharger speed (N) and an engine speed (Ne) O ) export; program code instructions for determining whether the current operating point is on the high flow side of the threshold line or on the low flow side of the threshold line; as well as When it is determined that the current operating point is on the high flow side of the threshold line where the desired state of the inlet regulating mechanism is open and when The measured value of When the theoretical value of the inlet regulating mechanism differs by more than a predetermined tolerance, program code instructions are used to determine that the inlet regulating mechanism is in a failure mode.

8. The computer program product of claim 7, further comprising program code instructions for checking for flow instability in the air inlet of the compressor upon determining that the current operating point is on the low flow side of the threshold line, and if flow instability is detected, determining based on the first compressor map (MAP) O ), at the measured compressor pressure ratio (PR), determine the flow rate during surge (W S-O ), and when the compressor flow rate (W m ) and the determined surge flow rate (W S-O ) differ by less than a predetermined tolerance, it is determined that surge may be about to occur.

9. The computer program product of claim 7, further comprising program code instructions for taking action to prevent an overspeed condition of the turbocharger when the inlet regulating mechanism is in a fault mode.

10. The computer program product of claim 8, further comprising program code instructions for taking action to prevent compressor surge when it is determined that surge may be imminent.

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