METHOD AND SYSTEM FOR DIAGNOSTIC A MALFUNCTION IN AN ACTIVE GRILLE COVER SYSTEM IN A HYBRID ELECTRIC VEHICLE

Abstract

Method for diagnosing a system malfunction of an active grille cover system in a hybrid electric vehicle (10), comprising: with a control unit (32), checking a cover movement and deriving a cover position based on a stall current of a cover drive motor (30) monitored by a first device (44) and a current drawn by a hybrid electric vehicle traction motor (12) monitored by a second device (48); Triggering a diagnosis of the active grid cover system (26) in response to the absence of sensor data from a grid cover sensor (38) indicating a cover movement; Completion of the diagnostics of the active grid cover system during a drive in the stationary operating state of the hybrid electric vehicle (10) in all-electric mode; and Driving the cover drive motor (30) into a first limit position in a first direction at the stall current on command of the control unit (32) and monitoring with the second device (48) with regard to any change in the average current consumption of the hybrid electric vehicle traction motor (12).

Description

TECHNICAL AREA

[0001] This document generally concerns the field of motor vehicle equipment and in particular a method and a system for diagnosing a malfunction in an active grille cover system in a hybrid electric vehicle. GENERAL STATE OF THE ART

[0002] Newer vehicles are being introduced with active grille shutters to meet stricter fuel economy standards. During operation, the active grille shutters close automatically to block airflow through the cooling system when cooling is not required. In the closed position, the active grille shutters help improve aerodynamics by reducing drag, with the greatest benefit at higher vehicle speeds. At other times, the active grille shutters open as needed to lower engine temperatures under the hood. The active grille shutter (AGS) system also helps control coolant temperatures, HVAC performance, and exhaust emissions depending on the vehicle's speed. During normal operation, the grille shutters are fully open when the engine is off.During a cold start, the grille covers remain closed as long as possible to help the engine reach its most efficient operating temperatures more quickly. This helps to reduce fuel consumption and emissions.

[0003] AGS systems typically include an electronic control unit (ECU) or control and AGS sensors, such as Hall-effect sensors, which provide information about the current position of the grille covers back to the control unit. Typically, the AGS sensors are self-calibrated when the vehicle is first switched on.

[0004] There are many failure modes associated with an AGS system. The grille covers might be stuck, yet the sensors could still function. The mechanical links that operate the grille covers can deteriorate over time. The DC cover drive motor might function correctly, but the connection could fail when there is no load. Furthermore, the Hall effect sensors can be damaged or contaminated by the environment in a way that prevents them from functioning normally. In this situation, the sensors will not provide the control unit with data on the current position of the grille covers.

[0005] While it's possible to deduce from a rising engine temperature that the grille covers are in the closed position, this isn't necessarily true in cold climates. Furthermore, in hybrid electric vehicles (HEVs), the vehicle can be driven in pure electric mode (EV mode), and the engine temperature may not change. Additionally, if the AGS system is stuck in the open position while driving in EV mode, the vehicle is subject to additional aerodynamic drag. Ideally, the AGS system should be closed when driving in EV mode if the combustion engine is cold and not running.This document relates to a new and improved method and system that performs a rationality check of the AGS system to determine whether the AGS sensors are functioning rationally and correctly, or whether the grille covers are mechanically stuck or fail to move for this or any other reason, such as a faulty connection. Advantageously, the new method and system checks the cover movement and derives a cover position based on (a) the stall current of the cover drive motor and (b) the current drawn by the HEV traction motor.

[0006] US 2014 / 0129078 A1 discloses an active air flap system for a vehicle and a method for diagnosing defects in the flap control, which allows differentiation between sensor and mechanical faults. US 2013 / 0338870 A1 discloses a system and method for diagnosing mechanical faults of an active grille cover system, which monitors mechanical fault conditions based on temperature and fault signals and triggers extended diagnostics. DE 10 2011 011 651 A1 discloses a flap control system and method for aerodynamic flaps, which reduces drag and controls regenerative braking, taking into account operating parameters such as brake and throttle valve positions. DE 10 2012 218 009 A1 discloses an active radiator grille closure system with a dual-torque actuator that provides higher torque for removing ice and snow from the slats in freezing and precipitation conditions. SUMMARY

[0007] In accordance with the purposes and benefits described herein, a method for diagnosing an AGS system malfunction in a HEV is provided. This method includes verifying the cover movement and deriving the cover position based on (a) a stall current from a cover drive motor and (b) a current drawn from an HEV traction motor.

[0008] According to the invention, the method further comprises the step of triggering an AGS diagnosis in response to a lack of AGS sensor data indicating a cover movement. The method further comprises the step of monitoring an electric current drawn by the cover drive motor using a first sensor. Additionally, according to the invention, the method comprises the step of monitoring an electric current drawn by the HEV traction motor using a second sensor.

[0009] Furthermore, the method according to the invention includes the step of completing the AGS diagnosis during a drive in the steady-state operating condition of the HEV in EV mode. More precisely, the method comprises (a) driving the cover drive motor to a first limit position in a first direction at the stall current upon command of a control unit and (b) monitoring with the second sensor for any change in the average current consumption of the HEV traction motor.

[0010] Furthermore, the procedure may include the following steps: (a) driving the cover drive motor to a second limit position in a second direction at the stall current on command from the control unit, and (b) monitoring with the second sensor for any change in the average current draw of the HEV traction motor, wherein (i) an increase in the average current draw indicates movement of the covers to an open position, (ii) a decrease in the average current draw indicates movement of the covers to a closed position, (iii) a change in the average current draw indicates an AGS sensor malfunction, and (iv) no change in the electrical current drawn by the cover drive motor indicates that the covers are stuck.

[0011] According to a further aspect, a procedure for controlling AGS operation in the event of an AGS sensor malfunction is provided. This procedure comprises the steps of confirming an AGS sensor malfunction using the methods described above and deriving the cover position by driving the cover drive motor via a command from the control unit to (a) the first limit position in the first direction at the stall current or (b) the second limit position in the second direction at the stall current, wherein the first limit position corresponds to fully closed covers and the second limit position corresponds to fully open covers.

[0012] According to another aspect, an AGS system is provided for a HEV. This AGS system can be comprehensively described as a plurality of covers, a cover drive motor for moving the plurality of covers between an open position and a closed position, an AGS sensor for monitoring a current cover position, and a control unit. This control unit is configured to command the operation of the cover drive motor and to initiate an AGS diagnostic in response to a lack of data received from the AGS sensor indicating cover movement. In at least one possible embodiment, the AGS system further includes a first sensor for monitoring the electrical current drawn by the cover drive motor and a second sensor for monitoring the electrical current drawn by the traction motor of the EHV.

[0013] Furthermore, the AGS system can include a control unit configured to monitor the cover movement and derive the cover position based on (a) the stall current of the cover drive motor and (b) the current drawn by the traction motor. The AGS system can also include a control unit configured to complete AGS diagnostics during a drive in the HEV's steady-state operating condition in EV mode. Additionally, the control unit can be configured to drive the cover drive motor to a first limit position in a first direction at the stall current and monitor any changes in the traction motor's average current draw using data received from the second sensor.

[0014] Furthermore, the AGS system can include a control unit configured to drive the cover drive motor to a second limit position in a second direction at the stall current and to monitor any changes in the average current draw of the traction motor using data received from the second sensor. In such a system, an increase in average current draw indicates movement of the covers to an open position. Conversely, a decrease in average current draw indicates movement of the covers to a closed position. Furthermore, any change in average current draw indicates an AGS sensor malfunction. Finally, no change in the electrical current drawn by the cover drive motor indicates that the covers are stuck.

[0015] Furthermore, the AGS system may include a control device that is further configured to confirm an AGS sensor fault and to derive a cover position by driving the cover drive motor to (a) the first limit position in the first direction at the stall current or (b) the second limit position in the second direction at the stall current, wherein the first limit position corresponds to fully closed covers and the second limit position corresponds to fully open covers.

[0016] The following description presents and illustrates several preferred embodiments of the method and system. It is understood that the method and system can assume further different embodiments and that their various details can be modified in various obvious aspects without deviating from the method and system as set forth and described in the following claims. Accordingly, the drawings and descriptions should be considered illustrative and not limiting. BRIEF DESCRIPTION OF THE DRAWING FIGURES

[0017] The accompanying diagrams, which are included here and form part of the description, illustrate several aspects of the process and system and, together with the description, serve to explain certain principles. The diagrams show: Fig. 1 A schematic block diagram of an HEV vehicle powertrain. Fig. 2 a schematic block diagram of the new and improved AGS system for a HEV. Fig. 3 A perspective view of an AGS system showing the covers in the closed position. Fig. 4 A perspective view of an AGS system showing the covers in an open position.

[0018] Reference will now be made in detail to the present preferred embodiments of the method and system, examples of which are shown in the accompanying drawing figures. DETAILED DESCRIPTION

[0019] It will now be on Fig. Reference is made to Figure 1, which schematically represents a typical powertrain for a hybrid electric vehicle, or HEV 10. As shown, the HEV 10 comprises a traction motor 12 and an internal combustion engine 14, both adapted to drive the vehicle's wheels 16 through the powertrain, generally referred to by reference numeral 18. As shown, the traction motor 12 receives power from a battery 20 via a converter 22. In contrast, the internal combustion engine 14 receives combustible fuel from the reservoir 24. Typically, the HEV 10 operates in one of three modes. In electric, or EV, mode, only the traction motor 12 is used to drive the wheels 16 through the powertrain 18. In hybrid mode, both the traction motor 12 and the internal combustion engine 14 are used to drive the wheels 16 through the powertrain 18.In contrast, in combustion mode only the combustion engine 14 is used to drive the wheels 16 through the drive train 18.

[0020] It will now be referred to as Fig. Reference is made to Figures 2-4, which represent the new and improved AGS system 26. This AGS system 26 includes a plurality of grille covers 28, which are moved by an electric cover drive motor 30 between a fully closed position, as shown in Figures 2-4. Fig. 3, and a fully open position, as shown in Fig. 4, can be moved. In the fully closed position, the grille covers 28 prevent airflow through the cooling module under the vehicle's hood, thereby increasing the vehicle's aerodynamic efficiency. In contrast, in the fully open position, as shown in Fig. 4. Allow airflow through the cooling module under the hood as needed to ensure the proper operation of the HEV 10.

[0021] More precisely, the AGS system 26 includes a control unit 32 in the form of a computing device, such as a dedicated microprocessor or an electronic control unit (ECU), which operates according to instructions from suitable software.

[0022] As shown, the control unit 32 includes one or more data inputs 34 for receiving data from a variety of sensors, detectors, monitors, or other devices 36, such as other control units, wherein this data relates to parameters such as vehicle speed, internal combustion engine temperature, HVAC power, coolant temperature, exhaust emissions, and the like. An AGS sensor 38, such as a Hall effect sensor, provides feedback data to the control unit 32 at the data input 40, which determines the current position of the grille covers 28.

[0023] What's next in Fig. As shown in Figure 2, the control unit 32 also includes a data input 42, which is connected to a cover drive motor current sensor 44 or an associated control module or control device that provides data relating to the current drawn by the cover drive motor 30. Additionally, the control device 32 includes a data input 46, which is connected to an HEV traction motor current sensor or another device, such as another control unit or control module, that provides data relating to the current drawn by the traction motor 12.

[0024] As already mentioned in the section<Allgemeiner Stand der Technik> As mentioned in this document, an AGS system 26 is subject to many different failure modes, including modes involving the AGS sensor 38, the cover drive motor 30, and the connection between the cover drive motor 30 and the covers 28. Advantageously, the control unit 32 is configured to diagnose an AGS system fault in an HEV 10 and even to ensure proper operation of the covers 28 if the AGS sensor 38 experiences a fault condition.

[0025] For this purpose, the control unit 32 is configured to command operation of the cover drive motor 30 and to initiate an AGS diagnostic in response to a failure to receive cover movement data from the AGS sensor 38 at data input 40. The control unit 32 can further be configured to check the cover movement and derive a cover position based on the stall current of the cover drive motor 30 and the current drawn by the traction motor 12, as indicated by the sensors or devices 44, 48 at data inputs 42, 46, respectively.

[0026] More precisely, the control unit 32 is configured to complete the AGS diagnostics during a drive in the steady-state operating condition of the HEV 10 in EV mode, with the HEV being driven only by the traction motor 12. For best results, this is achieved during a drive in steady-state operating condition on a country road, preferably at a constant speed on relatively flat roads.

[0027] More precisely, the control unit 32 is configured to drive the cover drive motor 30 to a first limit position in a first direction at the stall current and to monitor any changes in the average current consumption of the traction motor 12 using data received from the sensor or device 48 at the data input 46. Furthermore, the control unit 32 is configured to then drive the cover drive motor 30 to a second limit position in a second direction at the stall current and again to monitor any changes in the average current consumption of the traction motor 12 using data received from the sensor device 48 at the data input 46. When this occurs, an increase in the average current consumption indicates a movement of the covers 28 into an open position.A decrease in the average current draw indicates that the covers 28 are moving into a closed position. Simultaneously, a change in the average current draw indicates a fault in the AGS sensor 38. Furthermore, the absence of any change in the electrical current drawn by the cover drive motor 30, as indicated by the sensor device 44 at input 42, indicates that the covers 28 are stuck for any reason, such as a faulty connection between the drive motor and the covers.

[0028] Furthermore, the control unit 32 is configured to acknowledge any AGS sensor fault and to derive a cover position by driving the cover drive motor 30 to the first limit position in the first direction at the stall current or to the second limit position in the second direction at the stall current. The first limit position corresponds to the fully closed covers 28, as shown in Fig. 3 shown, and the second limit position corresponds to the fully opened covers, as in Fig. 4 shown.

[0029] In accordance with the above description, a procedure for diagnosing an AGS system malfunction in an HEV 10 is provided. This procedure can be broadly described as including the steps of checking for cover movement and deriving a cover position based on the stall current of a cover drive motor 30 and the current drawn by the HEV traction motor 12.

[0030] The method includes triggering an AGS diagnosis in response to a lack of AGS sensor data indicating cover movement. The method further includes monitoring the electrical current drawn by the cover drive motor 30 by a first device 44 and monitoring the electrical current drawn by the HEV traction motor 12 by a second device 48.

[0031] As already indicated, the procedure also includes completing the AGS diagnosis during a drive in the stationary operating state of the HEV 12 in EV mode.

[0032] More precisely, the procedure comprises the following steps: (a) driving the cover drive motor 30 to a first limit position in a first direction at the stall current for the cover drive motor upon command from the control unit 32, and (b) monitoring with the second device 48 for any change in the average current draw of the HEV traction motor 12. Any increase in the average current draw indicates movement of the covers 28 into an open position. Conversely, a decrease in the average current draw indicates movement of the covers 28 into a closed position. Furthermore, any change in the average current draw indicates that the covers are moving between an open and a closed position, and the AGS sensor is not detecting this movement and is therefore experiencing a malfunction.Furthermore, no change in the electrical current drawn by the cover drive motor 30 indicates that the covers 28 are stuck for any reason.

[0033] The procedure then includes the following steps: Driving the cover drive motor 30 into a second limit position at the stall current upon command of the control unit 32, and monitoring by the second device 48 for any change in the average current draw of the HEV traction motor 12. Again, an increase in the average current draw indicates movement of the covers 28 into an open position, while a decrease in the average current draw indicates movement of the covers into a closed position. Once more, any change in the average current draw indicates cover movement and thus an AGS sensor malfunction. No change in the electrical current drawn by the cover drive motor 30 indicates that the covers 28 are stuck for some reason.

[0034] Furthermore, a method for controlling AGS operation in the event of an AGS sensor failure is provided. This method comprises the steps of confirming an AGS sensor fault using the method described above. This is followed by the step of deriving the cover position by driving the cover drive motor 30 via a command from the control unit 32 to (a) the first limit position in the first direction at the stall current or (b) the second limit position in the second direction at the stall current, wherein the first limit position corresponds to the covers 28 in the fully closed position, as shown in Fig. 3 is shown, while the second limit position corresponds to the covers in the fully open position, as shown in Fig. 4 shown.

[0035] The method and system 26 disclosed here offer significant benefits and numerous advantages. First, they can diagnose whether an AGS system malfunction exists in the AGS sensor 38 or whether the covers 28 are simply stuck for some other reason, such as a faulty connection between the covers and the cover drive motor 30. It is understood that this data and indication can be used to perform maintenance work on the vehicle in the workshop more efficiently and effectively. Additionally, the system 26 and the method enable the proper operation of the covers 28 even if the AGS sensor 38 is not functioning correctly and is not providing feedback to the control unit 32 regarding the current position of the covers 28. Thus, the HEV 10 can still be operated at peak performance until the AGS sensor malfunction is rectified.

[0036] The foregoing has been presented for illustrative and descriptive purposes. It is neither intended to be exhaustive nor to limit the embodiments to the exact form disclosed. Obvious modifications and variations are possible in light of the above teachings. For example, if, while driving in mixed gasoline / electric mode, an increase in engine coolant temperature suggests that the covers 28 are stuck in a closed position, the control unit 32 may be configured to invoke EV mode in order to perform the AGS system diagnostics described in this document. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and reasonably entitled.

Claims

[1] Method for diagnosing a system malfunction of an active grid cover system in a hybrid electric vehicle (10), comprising: with a control unit (32), checking a cover movement and deriving a cover position based on a stall current of a cover drive motor (30) monitored by a first device (44) and a current drawn by a hybrid electric vehicle traction motor (12) monitored by a second device (48); Triggering a diagnosis of the active grid cover system (26) in response to the absence of sensor data from a grid cover sensor (38) indicating a cover movement; Completion of the diagnostics of the active grid cover system during a drive in the stationary operating state of the hybrid electric vehicle (10) in all-electric mode; and Driving the cover drive motor (30) into a first limit position in a first direction at the stall current on command of the control unit (32) and monitoring with the second device (48) with regard to any change in the average current consumption of the hybrid electric vehicle traction motor (12). [2] Method according to claim 1, further comprising driving the cover drive motor (30) into a second limit position in a second direction at the stall current on command of the control unit (32) and monitoring with the second device (48) with regard to any change in the average current consumption of the hybrid electric vehicle -traction motor (12), wherein an increase in the average current draw indicates a movement of the grid covers (28) into an open position, a decrease in the average current draw indicates a movement of the grid covers (28) into a closed position, a change in the average current draw indicates a malfunction of a sensor of an active grid cover system, and no change in the electrical current drawn by the cover drive motor (30) indicates that the grid covers (28) are stuck. [3] Method for controlling the operation of an active grid cover system in the event of a failure of a sensor of the active grid cover system, comprising: Confirming a malfunction of a sensor of the active grid cover system by means of the method set out in claim 2; and Deriving the cover position by driving the cover drive motor (30) via a command from the control unit (32) to the first limit position in the first direction at the stall current or the second boundary position in the second direction in the blocking current, wherein the first limit position corresponds to the fully closed grille covers (28) and the second limit position corresponds to the fully open grille covers (28). [4] Method for controlling the operation of an active grid cover system in the event of a failure of a sensor of the active grid cover system, comprising: Confirming a malfunction of a sensor of the active grid cover system by means of the method set out in claim 1; and Deriving the cover position by driving the cover drive motor (30) via a command from the control unit (32) to the first limit position or a second limit position in a second direction at the stall current, wherein the first limit position corresponds to the fully closed grid covers (28) and the second limit position corresponds to the fully open grid covers (28). [5] Active grille cover system (26) for a hybrid electric vehicle (10), comprising: a variety of grille covers (28); a cover drive motor (30) for moving the plurality of grille covers (28) between an open position and a closed position; a grid cover sensor (38) for monitoring a current cover position; a first device (44) that monitors the electrical current drawn by the cover drive motor (30), and a second device (48) that monitors the electrical current drawn by a traction motor (12) of the hybrid vehicle; and a control unit (32) configured to command the operation of the cover drive motor (30) and to initiate a diagnosis of the active grille cover system (26) in response to a lack of data received from the grille cover sensor (38) indicating the cover movement, to check the cover movement and to derive a cover position based on a stall current of the cover drive motor (30) monitored by a first device (44) and the current drawn by the traction motor (12) monitored by the second device (48), to complete a diagnosis of the active grille cover system during a drive in the steady-state operating condition of the hybrid electric vehicle (10) in all-electric mode,and to drive the cover drive motor (30) to a first limit position in a first direction at the stall current and to monitor, by means of data received from the second device (48), any change in the average current consumption of the traction motor (12). [6] Active grid cover system (26) according to claim 5, wherein the control unit (32) is further configured to drive the cover drive motor (30) to a second limit position in a second direction at the stall current and to monitor, by means of data received from the second device (48), any change in the average current consumption of the traction motor (12), wherein an increase in the average current consumption indicates a movement of the grid covers (28) into an open position, a decrease in the average current consumption indicates a movement of the grid covers (28) into a closed position, a change in the average current consumption indicates a malfunction of a sensor of the active grid cover system, and no change in the electrical current drawn by the cover drive motor (30) indicates that the grid covers (28) are stuck. [7] Active grid cover system (26) according to claim 6, wherein the control unit (32) is further configured to confirm a fault of a sensor of the active grid cover system and to derive the cover position by driving the cover drive motor (30) to (a) the first limit position in the first direction at the stall current or (b) the second limit position in the second direction at the stall current, wherein the first limit position corresponds to the fully closed grid covers (28) and the second limit position corresponds to the fully open grid covers (28).

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