Engine operation based on starter generator temperature

Abstract

The present disclosure relates to engine operation based on the temperature of a starter generator. A vehicle includes an engine and a controller. The controller may be configured to: in response to an indication that the temperature of the starter generator exceeds a degradation threshold, command the engine to start and prohibit the engine from automatically shutting down. And the controller may be configured to: in response to an indication that the temperature exceeds a disable threshold, or an indication that the temperature exceeds a degradation threshold and the traction battery discharge power is less than a threshold, command the engine to start and reduce the load.

Description

Technical Field

[0001] The present disclosure relates to a control system for a hybrid vehicle in which an internal combustion engine is operated based on a temperature of an integrated starter generator. Background Art

[0002] Vehicles typically use a transmission to transfer power between an internal combustion engine and the vehicle's wheels. Hybrid vehicles and micro-hybrid vehicles may include a control system configured to stop the vehicle's engine in order to improve fuel economy and reduce emissions. In a particular architecture, the vehicle may also have a traction motor connected to the transmission input, wherein the traction motor is electrically connected to a traction battery. The motor may be used in an electric mode or in a generating mode, in which energy from the battery is used to supplement engine power, and in a generating mode, the motor converts mechanical energy into electrical energy and stores it in the battery. Some vehicles also include a starter generator (such as a belt-driven integrated starter generator (BISG)) electrically connected to an auxiliary battery (usually a low-voltage battery). Vehicles with a BISG can supply power to the low-voltage battery via the BISG or the traction motor / traction battery. Summary of the invention

[0003] A vehicle includes an engine and a controller. The controller may be configured to: command an engine start and inhibit an automatic engine shutdown in response to an indication that a temperature of a starter generator exceeds a degradation threshold. And the controller may be configured to: command an engine start and reduce load in response to an indication that the temperature exceeds a disable threshold, or an indication that the temperature exceeds a degradation threshold and a traction battery discharge power is less than a threshold.

[0004] A vehicle includes an engine, an integrated starter generator (ISG), and a controller. The controller may be configured to: command an engine start and inhibit an automatic engine shutdown in response to an indication that a temperature of the ISG exceeds a degradation threshold, the degradation threshold being greater than a percentage of the Curie temperature, wherein the percentage is associated with a permanent magnetic field strength (PMFS) having a value of 1 / 2 of a PMFS at 0 degrees Celsius.

[0005] According to one embodiment of the present invention, the ISG is a belt drive ISG.

[0006] A method for controlling a vehicle includes performing the following operations by a controller: in response to receiving an indication that the temperature of an integrated starter generator (ISG) exceeds a degradation threshold, commanding an engine connected to the ISG to start and prohibiting engine shutdown; and in response to receiving an indication that the temperature exceeds a disable threshold, disabling a low voltage load.

[0007] According to one embodiment of the present invention, the ISG is a belt drive ISG. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 Schematic diagram of a hybrid vehicle including a belt-driven starter-generator.

[0009] Figure 2 FIG. 4 is a graph showing the torque command distribution of the starter generator relative to the temperature.

[0010] Figure 3 1 is a control diagram showing a method of controlling an engine of a vehicle having an integrated starter generator based on a state of the integrated starter generator.

[0011] Figure 4 The present invention is a state diagram of a method of controlling an engine of a vehicle having an integrated starter generator based on a state of the integrated starter generator. DETAILED DESCRIPTION

[0012] As required, detailed embodiments of the present invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely examples of the present invention, which may be implemented in various alternative forms. The drawings are not necessarily drawn to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, the specific structural and functional details disclosed herein should not be interpreted as limiting, but merely as a representative basis for teaching those skilled in the art to utilize the present invention in various aspects.

[0013] In hybrid vehicles, a disconnect clutch, a starter, or a belt-driven integrated starter generator (BISG or ISG) may be used to start the engine. However, as the temperature of the ISG increases, the magnetization of the magnets of the ISG decreases. For example, the Curie temperature (Tc) or Curie point of a material is the temperature at which the material loses its permanent magnetic properties. Typically, when the temperature of the magnet approaches the Curie temperature, the magnetism drops rapidly. For example, a magnet may be able to exert enough force to lift (i.e., overcome gravity) 25 washers at 0 degrees Celsius, however, when the temperature of the magnet increases to 100 degrees Celsius, the same magnet may only be able to lift 5 washers. The strength of a permanent magnet may be referred to as a permanent magnetic field strength (PMFS). An ISG or BISG may use permanent magnets in a rotor to generate a rotating magnetic field that rotates based on an induction field generated by a current flowing through a stator winding. The torque of the motor may be proportional to the PMFS, which is related to the temperature of the permanent magnet. Therefore, the energy generation capacity of a motor (e.g., an ISG) decreases as the temperature increases. In the case of the ISG, if the temperature of the ISG increases such that the torque generation capability at the temperature drops to a level below a threshold required to start an internal combustion engine (ICE), the ISG will be unable to start the ICE and the battery may be depleted. Here, the ICE is started when the temperature of the ISG exceeds a threshold (e.g., a degradation threshold), and the ICE continues to operate until the temperature of the ISG drops below a low threshold.

[0014] For example, consider an ISG with four operating conditions (level 0, level 1, level 2, and level 3). The first operating condition is level 0, where the temperature of the ISG is below a low threshold. Operation at level 0 is considered normal operation. Next is level 1, where the ISG is operated when the temperature of the ISG is below an intermediate threshold. Level 1 can be considered a hysteresis region, in which the configuration of the auto start / auto stop remains unchanged. Level 2 is to operate the ISG when the temperature of the ISG is above the intermediate threshold but below the high temperature threshold. Typically, the intermediate threshold is within a predetermined range from the high temperature threshold or the upper threshold. If the temperature of the ISG exceeds the intermediate threshold (e.g., the degradation threshold), external cooling of the ISG is desired. Cooling during level 2 can be achieved by operating a fan to circulate air around the ISG. The final level is level 3, that is, when the temperature of the ISG exceeds the upper threshold or the high temperature threshold (e.g., the disable threshold). At this point, the operation of the ISG is stopped, and in addition to performing active cooling, the power usage of the low voltage load is reduced. Reducing power usage may include disabling comfort and convenience loads (including seat heaters, seat ventilation, rear seat video displays, air conditioning A / C compressor, positive thermal coefficient (PTC) heaters). However, reducing power may also include reducing power used by non-comfort and convenience loads, such as reducing the power of PTC heaters, rear seat climate, steering wheel heating, front seat climate / heating / ventilation, rear blower, front windshield heater, wiper parking area heating, rear defroster, and rearview mirror heating. In this example, the degradation threshold may be a temperature at a first percentage of the Curie temperature (e.g., 25%, 33%, 40%, or 50%), and the disabling threshold may be a temperature at a second percentage of the Curie temperature (e.g., 50%, 60%, 66%, or 75%).

[0015] Reference Figure 1 , a schematic diagram of a hybrid electric vehicle (HEV) 10 according to an embodiment of the present disclosure is shown. The HEV 10 includes a powertrain 12. The powertrain 12 includes an engine 14 for driving a transmission 16, which may be referred to as a modular hybrid transmission (MHT). As will be described in more detail below, the transmission 16 includes an electric machine (e.g., an electric motor / generator (M / G) 18), an associated traction battery 20, a torque converter 22, and a multi-step ratio automatic transmission or gearbox 24. Although the vehicle is shown as an HEV 10, by removing selective HEV components (including the M / G 18, power electronics 56, and disconnect clutch 26), the vehicle is shown as components used in a conventional internal combustion engine (ICE) vehicle.

[0016] Both the engine 14 and the M / G 18 are used as drive sources and are configured to propel the HEV 10. The engine 14 may be an internal combustion engine fueled by gasoline, diesel, or natural gas, or a fuel cell. The engine 14 generates engine power and corresponding engine torque, which is supplied to the M / G 18 when a disconnect clutch 26 between the engine 14 and the M / G 18 is at least partially engaged. The M / G may be a permanent magnet synchronous motor or any of a variety of types of electric machines. Power electronics facilitate the flow of direct current (DC) power provided by the battery 20 to the M / G 18.

[0017] When the disconnect clutch 26 is at least partially engaged, power flow from the engine 14 to the M / G 18 or from the M / G 18 to the engine 14 is possible. For example, the disconnect clutch 26 can be engaged, and the M / G 18 can be operated as a generator to convert rotational energy provided by the crankshaft 28 and the M / G shaft 30 into electrical energy stored in the battery 20. The disconnect clutch 26 can also be disengaged to isolate the engine 14 from the rest of the powertrain 12, so that the M / G 18 can be used as the sole drive source for the HEV 10. The shaft 30 extends through the M / G 18. The M / G 18 is continuously drivably connected to the shaft 30, however, the engine 14 is drivably connected to the shaft 30 only when the disconnect clutch 26 is at least partially engaged.

[0018] The M / G 18 is connected to the torque converter 22 via the shaft 30. Thus, when the disconnect clutch 26 is at least partially engaged, the torque converter 22 is connected to the engine 14. The torque converter 22 includes a pump wheel fixed to the M / G shaft 30 and a turbine wheel fixed to the transmission input shaft 32. Thus, the torque converter 22 provides a fluid coupling between the shaft 30 and the transmission input shaft 32. The torque converter 22 transfers power from the pump wheel to the turbine wheel when the pump wheel rotates faster than the turbine wheel. The magnitude of the turbine torque and the pump wheel torque generally depends on the relative speed. When the ratio of the pump wheel speed to the turbine speed is high enough, the turbine torque is several times the pump wheel torque. A torque converter bypass clutch (also known as a torque converter lockup clutch) 34 may also be provided, which, when engaged, frictionally or mechanically connects the pump wheel and the turbine wheel of the torque converter 22 to allow for more efficient power transfer. The torque converter bypass clutch 34 may be operated as a starting clutch to provide a smooth vehicle launch. Alternatively, for applications that do not include a torque converter 22 or a torque converter bypass clutch 34 , a launch clutch similar to the disconnect clutch 26 may be provided between the M / G 18 and the gearbox 24 .

[0019] The gearbox 24 is a gear transmission that includes a collection of rotating elements and clutches configured to impose a specific speed relationship between the rotating elements. Some speed relationships that are imposed regardless of the state of any clutch are referred to as fixed speed relationships. Gear transmissions that only impose fixed speed relationships are referred to as fixed gear transmissions. Other speed relationships are only imposed when a specific clutch is fully engaged. Gear transmissions that selectively impose speed relationships are referred to as switchable gear transmissions. A discrete ratio transmission has a switchable gear transmission for selectively applying various gear ratios between an input shaft and an output shaft.

[0020] A group of elements is fixedly connected to one another if it is constrained to rotate as a unit under all operating conditions. Elements may be fixedly connected by spline connection, welding, press fitting, machining of a general solid, or other methods. Slight changes in rotational displacement may occur between fixedly connected elements, such as displacement due to impact or shaft compliance. In contrast, two elements are selectively connected by a clutch, which constrains the two elements to rotate as a unit whenever the clutch is fully engaged, and the two elements are free to rotate at different speeds under at least some other operating conditions. Clutches include actively controlled devices (such as hydraulically or electrically actuated clutches) and passive devices (such as one-way clutches). A clutch that holds an element from rotating by selectively connecting the element to a housing may be referred to as a brake.

[0021] The gear transmission can be controlled by a shift schedule that connects and disconnects specific elements of the gear set to control the gear ratio between the transmission output shaft 36 and the transmission input shaft 32. The gearbox 24 is automatically switched from one gear ratio to another gear ratio based on various vehicle operating conditions and environmental conditions by an associated controller (such as a powertrain control unit (PCU)). In another example, the transmission can be a manual transmission. Power and torque from both the engine 14 and the M / G 18 can be transmitted to and received by the gearbox 24. The gearbox 24 then provides the powertrain output power and torque to the output shaft 36.

[0022] The output shaft 36 is connected to a differential 40. The differential 40 drives a pair of wheels 42 via respective axles 44 connected to the differential 40. The differential delivers substantially equal torque to each wheel 42 while allowing for slight rotational speed differences, such as when the vehicle is turning. Different types of differentials or similar devices may be used to distribute torque from the drivetrain to one or more wheels. In some applications, the torque distribution may be different depending on the particular operating mode or condition.

[0023] The powertrain 12 also includes an associated controller 50 (such as a powertrain control unit (PCU)). Although shown as one controller, the controller 50 may be part of a larger control system and may be controlled by various other controllers throughout the vehicle 10 (such as a vehicle system controller (VSC)). Therefore, it should be understood that the powertrain control unit 50 and one or more other controllers may be collectively referred to as a "controller" that controls various actuators in response to signals from various sensors to control multiple functions (such as starting / stopping the engine 14, operating the M / G 18 to provide wheel torque or charging the battery 20, selecting or planning transmission shifts, etc.). The controller 50 may include a microprocessor or central processing unit (CPU) that communicates with various types of computer-readable storage devices or media. The computer-readable storage devices or media may include, for example, volatile and non-volatile memory in a read-only memory (ROM), a random access memory (RAM), and a keep-alive memory (KAM). KAM is a persistent or non-volatile memory that can be used to store various operating variables when the CPU loses power. The computer readable storage device or medium may be implemented using any of a number of known storage devices such as PROM (programmable read-only memory), EPROM (electrically programmable read-only memory), EEPROM (electrically erasable programmable read-only memory), flash memory, or any other electrical, magnetic, optical, or combined storage device capable of storing data, some of which represents executable instructions used by the controller to control the engine or vehicle.

[0024] The controller communicates with various engine / vehicle sensors and actuators via an input / output (I / O) interface (including input channels and output channels), which may be implemented as a single integrated interface that provides various raw data or signal conditioning, processing and / or conversion, short circuit protection, etc. Optionally, one or more dedicated hardware or firmware chips may be used to condition and process specific signals before they are supplied to the CPU. Figure 1As generally shown in the representative embodiment of FIG. 1 , the controller 50 can transmit signals to and / or from the engine 14, the disconnect clutch 26, the M / G 18, the battery 20, the launch clutch 34, the transmission gearbox 24, and the power electronics 56. Although not explicitly shown, those of ordinary skill in the art will recognize the various functions or components within each of the above-mentioned subsystems that can be controlled by the controller 50. Representative examples of parameters, systems and / or components that may be directly or indirectly actuated using control logic and / or algorithms executed by the controller include fuel injection timing, rate and duration, throttle position, spark plug firing timing (for spark-ignition engines), intake / exhaust valve timing and duration, front end accessory drive (FEAD) components (such as, AC generator, air conditioning compressor), battery charging or discharging (including determining maximum charging power limit and maximum discharge power limit), regenerative braking, M / G operation, clutch pressures for the disengagement clutch 26, the starting clutch 34 and the transmission gearbox 24, etc. For example, sensors transmitting inputs through the I / O interface can be used to indicate turbocharger boost pressure, crankshaft position (PIP), engine speed (RPM), wheel speed (WS1, WS2), vehicle speed (VSS), coolant temperature (ECT), intake manifold pressure (MAP), accelerator pedal position (PPS), ignition switch position (IGN), throttle position (TP), air temperature (TMP), concentration or presence of exhaust oxygen (EGO) or other exhaust constituents, intake air flow (MAF), transmission gear, gear ratio or mode, transmission oil temperature (TOT), transmission turbine speed (TS), torque converter bypass clutch 34 state (TCC), deceleration or shift mode (MDE), battery temperature, voltage, current or state of charge (SOC).

[0025] The driver of the vehicle uses the accelerator pedal 52 to provide the required torque, power or drive command to propel the vehicle. Generally, depressing and releasing the accelerator pedal 52 generates an accelerator pedal position signal that can be interpreted by the controller 50 as a demand for increasing power or decreasing power, respectively. The driver of the vehicle also uses the brake pedal 58 to provide the required braking torque to slow the vehicle. Generally, depressing and releasing the brake pedal 58 generates a brake pedal position signal that can be interpreted by the controller 50 as a need to reduce the speed of the vehicle. Based on the inputs from the accelerator pedal 52 and the brake pedal 58, the controller 50 commands torque to the engine 14, the M / G 18 and the friction brake 60. The controller 50 also controls the shift timing in the gearbox 24 and the engagement or disengagement of the disconnect clutch 26 and the torque converter bypass clutch 34. Similar to the disconnect clutch 26, the torque converter bypass clutch 34 can be adjusted within a range between the engaged position and the disengaged position. In addition to the variable slip generated by the hydraulic coupling between the impeller and the turbine, this adjustment also generates variable slip in the torque converter 22. Alternatively, torque converter bypass clutch 34 may be operated to lock up or open without utilizing a regulated mode of operation, depending on the particular application.

[0026] An integrated starter generator (ISG) 64 may be connected to the engine 14 (i.e., may be connected to the crankshaft 28 of the engine 14). The ISG 64 may be configured to operate as a motor to start the engine 14 during an engine starting event, or to provide additional torque to the powertrain 12 during vehicle operation. The ISG 64 may also be configured to receive torque from the engine 14 and operate as a generator. The ISG 64 may be selectively connected to the engine via a clutch 66, a belt 68, and a pair of pulleys 70. If the ISG 64 is connected to the engine via a belt 68, the ISG 64 may be referred to as a belt-driven integrated starter generator (BISG). The controller 50 may be configured to send a signal to the ISG 64 to cause the ISG 64 to operate as a motor or a generator. The controller may also be configured to send a signal to the clutch 66 to cause the clutch 66 to be disconnected or closed. When the clutch is in a closed state, the ISG 64 will be connected to the engine 14, and when the clutch 66 is in a disconnected state, the ISG 64 will be separated from the engine 14. The ISG 64 can be configured to provide electrical energy to charge the auxiliary battery 72 (via a DC / DC converter) and the traction battery 20 when operating as a generator, or to provide electrical energy to power the vehicle accessories 62. In another example, the traction battery 20 can charge the auxiliary battery using a DC / DC voltage converter. The auxiliary battery 72 can also be configured to power the vehicle accessories 62.

[0027] The controller 50 may be configured to receive the Figure 110. The electrical signals may be transmitted from the various components to the controller 50 via the input channels. In addition, the electrical signals received from the various components may indicate a request or command for changing or modifying the state of one or more corresponding components of the vehicle 10. The controller 50 includes an output channel configured to transmit (via the electrical signals) the request or command to the various vehicle components. The controller 50 includes control logic and / or algorithms that are configured to generate requests or commands transmitted through the output channels based on the requests, commands, conditions or states of the various vehicle components.

[0028] exist Figure 1 2 and 3. In the embodiment of the present invention, the input channels and output channels are shown in dashed lines. It should be understood that a single dashed line can represent both the input channels and output channels entering or leaving a single element. In addition, the output channel of one element can be operated as the input channel of another element, and vice versa.

[0029] Figure 2 1 is a graphical representation 100 of a torque command 102 for a starter generator relative to a temperature 104. The graphical representation 100 shows torque command curves 106 at a low temperature threshold 108, a medium temperature threshold 110, and a high temperature threshold 112. Similarly, the graphical representation may use power instead of torque on the element 102, and the curve 106 indicates a power curve relative to the temperature 104. Here, the torque command is shown as having a torque command for an ISG (e.g., Figure 1 The controller is configured to provide a torque level for the ISG 64 of the engine, which is generally constant in region 0 when the temperature is less than a low temperature threshold 108 and in region 1 when the temperature of the ISG is less than a medium temperature threshold 110. However, when the temperature of the ISG exceeds the medium temperature threshold 110, the controller operates in region 2 until the temperature reaches an upper threshold 112, after which the controller operates in region 3. In region 2, the controller will adjust the torque level according to a curve (such as, Figure 2 When the temperature of the ISG exceeds the upper threshold 112, the controller will operate in region 3, in which the torque is reduced to a low torque level 114, and low voltage loads may be reduced or turned off.

[0030] Figure 3 The invention is based on a starter-generator integrated machine (for example, Figure 1 The state of the ISG 64) is used to control the engine of the vehicle having the starter generator (for example, Figure 1 A control diagram 200 of a method of an engine 14).

[0031] Here, the controller starts at operation 202, when the belt drive integrated starter generator BISG or ISG is in normal operation. In operation 202, the controller is configured to allow the engine (e.g., Figure 1 The engine 14) is automatically stopped and low voltage loads are enabled. Low voltage loads include PTC heater, rear seat climate, steering wheel heating, front seat climate / heating / ventilation, rear blower, front windshield heater, wiper parking area heating, rear defroster and rearview mirror heating. The controller will continue to operation 204.

[0032] At operation 204, the controller will receive a signal such as the thermal condition of the BISG. The thermal condition input may be an analog signal or a digital signal. The signal may be read directly from a sensor or may be sent by another controller or module. After receiving the thermal condition input, the controller will proceed to operation 206. At operation 206, when the state or condition is 0, the controller will branch to operation 208, if the state or condition is not 0, the controller will proceed to operation 210. For example, if the state is 1, 2, or 3, the controller will branch to operation 210.

[0033] At operation 208, low voltage loads are enabled and auto stop is enabled so that the engine can be selectively started and stopped. At operation 210, when the state of the ISG is 2 or 3, the controller will branch to operation 212. In all other states of the BISG, the controller will branch to operation 204. Therefore, if the state of the BISG is 1, the controller will branch back to operation 204, and the controller will not adjust or change the condition of the low voltage loads, nor start / stop the engine.

[0034] In operation 212, the controller will prohibit the automatic stop of the engine, and if the engine is stopped, the controller will automatically start the engine. After that, the controller will proceed to operation 214. In operation 214, when the state of the ISG is 3, the controller will branch to operation 216. If the state of the ISG is not 3, the controller will return to operation 204, and the controller will not adjust or change the condition of the low voltage load. In operation 216, the controller will limit or prohibit the operation of the low voltage load. For example, the PTC heater can be reduced to a predetermined level or disabled, the rear seat climate can be limited to a predetermined value or disabled, the steering wheel heating can be limited to a predetermined value (e.g., 65%) or disabled, the front seat climate / heating / ventilation can be disabled, the rear blower can be limited to a predetermined value (e.g., 75%) or disabled, the front windshield heater can be disabled, the wiper parking area heater can be disabled, the rear defroster can be disabled, and the rearview mirror heating can be disabled.

[0035] Figure 4300 is a state diagram of a method of controlling an engine of a vehicle having an integrated starter generator based on the state of the integrated starter generator. In the state diagram 300, when the system is in a normal operating state 302, the controller operates so that low voltage loads are enabled and auto stop is enabled so that the engine can be selectively started and stopped. When the condition is 0 or 1, the controller will keep the system in the normal operating state 302, however, when the condition is 2 or 3, the controller will set the system to the FMEM1 operating state 304.

[0036] In the FMEM 1 operating state 304, the controller will disable the auto stop function so that the engine will not automatically stop while running, and the controller will output a signal for automatically starting the engine. When the condition is 1 or 2, the controller will keep the system in the FMEM 1 operating state 304. When the condition is 0, the controller will set the system to the normal operating state 302, and when the condition is 3, the controller will set the system to the FMEM 2 operating state 306.

[0037] In the FMEM 2 operating state 306, the controller will limit or inhibit the operation of low voltage loads while keeping the auto stop disabled and keeping the engine running. For example, limiting or inhibiting the operation of low voltage loads may include: PTC heaters may be reduced to a predetermined level or disabled, rear seat climate may be limited to a predetermined value (e.g., 65%) or disabled, steering wheel heating may be limited to a predetermined value (e.g., 65%) or disabled, front seat climate / heating / ventilation may be disabled, rear blower may be limited to a predetermined value (e.g., 75%) or disabled, front windshield heater may be disabled, wiper parking zone heater may be disabled, rear defroster may be disabled, and rearview mirror heating may be disabled.

[0038] It should be noted that Figure 3 and Figure 4 The example of BISG mentioned four operating states of BISG, however, the concepts of the present invention may be applied to additional operating states. For example, a BISG having six operating states may operate in a normal operating state (e.g., 302) during BISG states 0, 1, 2, and may transition to an FMEM 1 operating state (e.g., 304) in response to a BISG state of 3, 4, or 5. Once in the FMEM 1 operating state, the controller may remain in operation when the BISG state is 2, 3, or 4, and transition back to the normal operating state (e.g., 302) when the BISG state is 0 or 1. In addition, the controller may transition to an FMEM 2 operating state (e.g., 306) in response to a BISG state of 5. Once in the FMEM 2 operating state, the controller may remain in operation when the BISG state is 2, 3, 4, or 5, and transition back to the normal operating state (e.g., 302) when the BISG state is 0 or 1.

[0039] In another example, considering that the BISG has six states, the FMEM 2 operating state (e.g., 306) may have two internal levels. Once in the FMEM 1 operating state, the controller may remain in operation when the BISG state is 2 or 3, and transition back to the normal operating state (e.g., 302) when the BISG state is 0 or 1. In addition, the controller may transition to the FMEM2 operating state (e.g., 306) in response to the BISG state being 4 or 5. Once in the FMEM 2 operating state, the controller may remain in operation when the BISG state is 2, 3, 4, or 5, and transition back to the normal operating state (e.g., 302) when the BISG state is 0 or 1. However, if the state is 4, the controller may limit specific loads (e.g., only rear seat climate, steering wheel heating, front seat climate / heating / ventilation, and rear blower may be limited to predetermined values ​​or disabled). And, if the state is 5, the controller may limit all available limitable loads.

[0040] The present disclosure provides representative control strategies and / or logic that can utilize one or more processing strategies (such as, event-driven, interrupt-driven, multi-tasking, multi-threading, etc.) to realize.Like this, each step or function shown here can be executed in the order shown, executed in parallel, or omitted in some cases.Although not always explicitly shown, it will be appreciated by those of ordinary skill in the art that one or more of the steps shown or functions can be repeatedly executed according to the specific processing strategy being used.Similarly, the features and advantages described herein do not necessarily require the processing sequence, and the processing sequence is provided only for the convenience of illustration and description.

[0041] The control logic may be implemented primarily in software executed by a microprocessor-based vehicle, engine, and / or powertrain controller. Of course, the control logic may be implemented in software, hardware, or a combination of software and hardware in one or more controllers, depending on the specific application. When the control logic is implemented in software, the control logic may be provided in one or more computer-readable storage devices or media, which store data representing codes or instructions executed by a computer to control a vehicle or its subsystems. The computer-readable storage device or medium may include one or more of a plurality of known physical devices, which utilize electrical, magnetic, and / or optical memory to store executable instructions and associated calibration information, operating variables, and the like. Optionally, the process, method, or algorithm may be implemented in whole or in part using suitable hardware components (such as, application specific integrated circuits (ASICs), field programmable gate arrays (FPGAs), state machines, controllers, or other hardware components or devices) or a combination of hardware components, software components, and firmware components.

[0042] Although the exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms covered by the claims. The words used in the specification are descriptive words rather than restrictive words, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As mentioned above, the features of each embodiment can be combined to form further embodiments of the present invention that may not be clearly described or shown. Although for one or more desired characteristics, each embodiment may have been described as providing advantages or being superior to other embodiments or prior art embodiments, it will be appreciated by those of ordinary skill in the art that one or more features or characteristics can be compromised to achieve the desired overall system properties according to specific applications and embodiments. These properties may include but are not limited to cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as being less desirable than other embodiments or prior art embodiments in one or more characteristics are not outside the scope of the present disclosure and can be expected to be used for specific applications.

Claims

1. A vehicle comprising: engine; as well as The controller is configured as: responsive to an indication that a temperature of the starter-generator exceeds a degradation threshold, commanding an engine start and inhibiting an automatic engine shutdown; In response to an indication that the temperature exceeds a disable threshold, or an indication that the temperature exceeds a degradation threshold and the traction battery discharge power is less than a threshold, commanding an engine start and reducing load; In response to an indication that the temperature has fallen below the degradation threshold and has fallen below a first threshold, engine shutdown is enabled, and wherein the first threshold is less than the degradation threshold and the degradation threshold is less than the disabling threshold.

2. The vehicle according to claim 1, wherein: The controller is further configured to enable automatic engine shutdown and enable loads in response to an indication that the temperature has dropped below the disable threshold and the degradation threshold.

3. The vehicle according to claim 2, wherein: The load is a seat heater, a seat ventilator, a positive thermal coefficient heating element or an air conditioning compressor.

4. The vehicle according to claim 1, wherein: The degradation threshold is greater than a first percentage of the Curie temperature, and wherein the first percentage is associated with a permanent magnetic field strength (PMFS) having a value of ½ of a PMFS at 0 degrees Celsius.

5. The vehicle according to claim 4, wherein: The disabling threshold is greater than a second percentage of the Curie temperature, and wherein the second percentage is associated with a PMFS having a value of ¼ of the PMFS at 0 degrees Celsius.

6. The vehicle according to claim 1, wherein: The starter generator is a belt-driven starter generator integrated machine.

7. A vehicle comprising: engine; Integrated starter generator (ISG); as well as The controller is configured as: In response to an indication that a temperature of the ISG exceeds a degradation threshold that is greater than a percentage of the Curie temperature, an engine start is commanded and an engine auto-shutdown is inhibited, wherein the degradation threshold is greater than a percentage of the Curie temperature, wherein the percentage is associated with a permanent magnetic field strength (PMFS) having a value of ½ of a PMFS at 0 degrees Celsius.

8. The vehicle according to claim 7, wherein: The controller is further configured to command the engine to start and reduce low voltage loads in response to an indication that the temperature of the ISG exceeds a disable threshold, or an indication that the temperature of the ISG exceeds a degrade threshold and the traction battery discharge power is less than a threshold, wherein the disable threshold is greater than another percentage of the Curie temperature and greater than the degrade threshold, and wherein the another percentage is associated with a PMFS having a value of ¼ of the PMFS at 0 degrees Celsius.

9. The vehicle according to claim 8, wherein: The controller is further configured to enable engine shutdown in response to an indication that a temperature of the ISG drops below the degradation threshold and drops below a first threshold, and wherein the first threshold is less than the degradation threshold and the degradation threshold is less than the disable threshold.

10. The vehicle according to claim 9, wherein: The controller is further configured to enable engine shutdown and allow low voltage loads to be enabled in response to an indication that a temperature of the ISG drops below the disable threshold, the degrade threshold, and the first threshold.

11. The vehicle according to claim 10, wherein: The low voltage load is a seat heater, a seat ventilation device, a positive thermal coefficient heating element or an air conditioning compressor.

12. A method of controlling a vehicle, comprising: Do the following via the controller: In response to receiving an indication that a temperature of an integrated starter generator (ISG) exceeds a degradation threshold, commanding an engine connected to the ISG to start and inhibiting an engine shutdown; disabling a load in response to receiving an indication that the temperature exceeds a disabling threshold; In response to an indication that the temperature has fallen below the degradation threshold and has fallen below a first threshold, engine shutdown is enabled, and wherein the first threshold is less than the degradation threshold and the degradation threshold is less than the disabling threshold.

13. The method according to claim 12, wherein: The degradation threshold is greater than a first percentage of the Curie temperature, and wherein the first percentage is associated with a permanent magnetic field strength (PMFS) having a value of ½ of a PMFS at 0 degrees Celsius.

14. The method according to claim 13, wherein: The disabling threshold is greater than a second percentage of the Curie temperature, and wherein the second percentage is associated with a PMFS having a value of ¼ of the PMFS at 0 degrees Celsius.

15. The method according to claim 12, wherein: In response to an indication that the temperature has dropped below the disable threshold and the degrade threshold, an automatic engine shutoff is enabled and loads are enabled.

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