Systems and methods for thermal regulation of vehicle system components

Abstract

The present invention relates to systems and methods for thermal regulation of vehicle system components. Methods and systems are provided for accelerating catalyst heating and cooling a vehicle's braking system by applying a magnetic field to a vehicle system component. In one example, a method includes applying a magnetic field to an exhaust system component disposed proximate the catalyst in response to the temperature of the catalyst being below a threshold temperature, and removing the magnetic field from the exhaust system component in response to the temperature reaching the threshold temperature. In another example, the method further includes applying a magnetic field to a braking system component after a vehicle braking event, and removing the magnetic field from the braking system component in response to a magnetic field deactivation condition being satisfied.

Description

Technical Field

[0001] The present invention generally relates to methods and systems for temperature regulation of components for vehicle systems. Background Art

[0002] Motor vehicles typically include a catalyst (also referred to herein as a catalytic converter) as an engine exhaust aftertreatment device. However, upon engine startup, especially under cold ambient conditions, the catalyst has not yet reached its optimal operating temperature (e.g., light-off temperature). Exhaust released before the catalyst reaches its light-off temperature can account for a large proportion of the total vehicle emissions. Thus, engine control systems can use various methods to accelerate catalyst heating to reduce the amount of time after engine startup before the catalyst reaches its light-off temperature, thereby reducing vehicle emissions. Generally, the various methods are aimed at increasing the amount of thermal energy reaching the catalyst, such as by increasing the exhaust gas temperature via retarded spark timing.

[0003] However, the inventors herein have recognized additional ways to further reduce the amount of time after engine startup before the catalyst reaches its light-off temperature. That is, the inventors herein have recognized that the magnetocaloric effect (MCE) can be used to reduce the amount of thermal energy required to achieve the catalyst light-off temperature, and the MCE can be used alone or in combination with other methods for accelerating catalyst heating by reducing the specific heat capacity of the catalyst. As an example, retarded spark timing can reduce fuel economy, reduce combustion stability, and increase engine vibration, and thus reducing the use of spark retard can increase fuel economy and reduce the occurrence of misfires.

[0004] In addition, the MCE can be used for thermal regulation of other vehicle system components, such as brake system components (e.g., brake rotors). Generally, to increase brake cooling, the size of the brake rotor is increased. Increasing the size of the brake rotor increases the thermal capacity and surface area of the rotor, which enables the brake system to absorb more thermal energy before the temperature increases and dissipate the thermal energy more quickly. However, increasing the size of the brake rotor also increases the unsprung rotating mass of the vehicle. The inventors herein have recognized that by using the MCE to reduce the specific heat capacity of the brake rotor, the rate at which the brake system dissipates heat to the surrounding environment can be increased without increasing the size of the brake rotor. Summary of the Invention

[0005] In one example, the above problem can be solved by a method for an engine that includes: in response to the temperature of an exhaust catalytic converter being lower than a first threshold temperature, applying a magnetic field to an exhaust system component disposed proximate to the exhaust catalytic converter; and in response to the temperature rising to or above the first threshold temperature, stopping the application of the magnetic field. In this way, the amount of time before the exhaust catalytic converter reaches its light-off temperature can be reduced.

[0006] As an example, for instance when the temperature of the exhaust catalytic converter is below a second lower threshold temperature, in addition to applying a magnetic field to the exhaust system components, alternative engine parameters such as retarded spark timing can be adjusted. In this way, the temperature of the exhaust catalytic converter can increase faster than when using spark retard or magnetic field alone, thereby further reducing the amount of time before the exhaust catalytic converter reaches its light-off temperature, and thus reducing vehicle emissions. As another example, the method can further include applying a magnetic field to a braking system component of a vehicle having an engine during a duration after a vehicle braking event; and in response to one or more of the temperature of the braking system component reaching a threshold temperature and the start of a subsequent braking event, stopping applying the magnetic field to the braking system component. By applying a magnetic field to the braking system component after braking, heat can be dissipated from the braking system while keeping the braking system smaller, thereby preventing the braking system from deteriorating due to overheating while reducing the total mass of the vehicle.

[0007] It should be understood that the above summary is provided to introduce in a simplified form a selection of concepts that are further described in the detailed description. This does not mean identifying key or essential features of the claimed subject matter, the scope of which is uniquely defined by the appended claims. Furthermore, the claimed subject matter is not limited to embodiments that solve any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 A schematic diagram of an example vehicle system is shown.

[0009] Figure 2 is a high-level flowchart of an example method for thermally regulating vehicle system components.

[0010] Figure 3 is a flowchart of an example method for accelerating catalyst heating via one or more of spark retard and magnetic field application.

[0011] Figure 4 An example diagram of applying a magnetic field during vehicle operation to thermally regulate vehicle system components is shown. DETAILED DESCRIPTION

[0012] The following description relates to systems and methods for applying a magnetic field to select vehicle system components (such as those depicted in an example vehicle system of Figure 1 to thermally regulate vehicle system components using the magnetocaloric effect (MCE). For example, a magnetic field can be applied to a braking system component after a braking event to increase the heat dissipation rate, such as according to an example method of Figure 2 or applied to an exhaust system component to, for example, according to Figure 2 and3 The exemplary method increases the rate of catalyst heating. In Figure 4 A predictive example timeline is shown in which a magnetic field is applied to an exhaust system component for catalyst heating and to a brake system component for brake system cooling.

[0013] Magnetocaloric effect (MCE) is a phenomenon in which the temperature of a magnetocaloric material is changed by exposing the magnetocaloric material to an alternating applied magnetic field (e.g., the magnetic field increases and then decreases). When the magnetic field is first applied, the magnetic domains of the magnetocaloric material align in the direction of the applied magnetic field. This reduces the magnetic degrees of freedom of the magnetocaloric material (e.g., reduces its magnetic entropy), thereby reducing its specific heat capacity and causing the temperature of the magnetocaloric material to increase (at least temporarily). The specific heat capacity of a material is the ratio of the heat absorbed (or removed from the material) to the resulting temperature change (per unit mass). Thus, by reducing the specific heat capacity of the magnetocaloric material via the applied magnetic field, a smaller amount of heat transferred into or out of the magnetocaloric material will result in a larger temperature change. If the temperature of the magnetocaloric material is greater than its surroundings, it can transfer heat to the surroundings, resulting in a temperature decrease. If the temperature of the magnetocaloric material is lower than its surroundings, it can absorb heat from the surroundings, resulting in a temperature increase. Thus, depending on the direction of heat transfer (e.g., into or out of the magnetocaloric material), MCE can be used for both heating and cooling. When the applied magnetic field is reduced or removed, the magnetic domains can become disoriented by the thermal energy present in the magnetocaloric material, thereby transferring the thermal energy (and entropy) to the magnetic entropy.

[0014] Turning now to the drawings, Figure 1 An exemplary embodiment of a cylinder 14 of an internal combustion engine 10 is depicted, which internal combustion engine 10 may be included in a vehicle 5. The engine 10 may be controlled at least in part by a control system including a controller 12 and by inputs from a vehicle operator 130 via an input device 132. In this example, the input device 132 includes an accelerator pedal and a pedal position sensor 134 for generating a proportional pedal position signal PP. A cylinder (also referred to herein as a “combustion chamber”) 14 of the engine 10 may include a combustion chamber wall 136 having a piston 138 positioned therein. The piston 138 may be coupled to a crankshaft 140 such that the reciprocating motion of the piston is converted into rotational motion of the crankshaft. As described further below, the crankshaft 140 may be coupled to at least one drive wheel 55 of a passenger vehicle via a transmission 54. Additionally, a starter motor (not shown) may be coupled to the crankshaft 140 via a flywheel to effect a starting operation of the engine 10.

[0015] In some examples, vehicle 5 can be a hybrid vehicle having multiple torque sources available for one or more wheels 55. In other examples, vehicle 5 is a conventional vehicle having only an engine or an electric vehicle having only (one or more) electric motors. In the illustrated example, vehicle 5 includes an engine 10 and an electric motor 52. Electric motor 52 can be a motor or a motor / generator. When one or more clutches 56 are engaged, the crankshaft 140 of engine 10 and electric motor 52 are connected to wheels 55 via a transmission 54. In the depicted example, a first clutch 56 is disposed between crankshaft 140 and electric motor 52, and a second clutch 56 is disposed between electric motor 52 and transmission 54. Controller 12 can send signals to the actuators of each clutch 56 to engage or disengage the clutches so as to connect crankshaft 140 to electric motor 52 and components connected to electric motor 52 or disconnect crankshaft 140 from electric motor 52 and components connected to electric motor 52, and / or connect electric motor 52 to transmission 54 and components connected to transmission 54 or disconnect electric motor 52 from transmission 54 and components connected to transmission 54. Transmission 54 can be a gearbox, a planetary gear system, or other types of transmissions. The powertrain can be configured in various ways, including as a parallel, series, or series-parallel hybrid vehicle.

[0016] Wheels 55 can include a braking system 59, and braking system 59 includes a brake 57 to slow the rotation of wheels 55. For example, brake 57 can be a friction brake, such as a disc brake or a drum brake, or an electromagnetic (e.g., electromagnetically actuated) brake. Both the friction brake and the electromagnetic brake use friction between components of the braking system to slow the rotation of wheels 55, thereby slowing the linear motion of vehicle 5. One or more components of braking system 59 (such as brake pads, brake rotors, etc.) can be at least partially composed of a magnetothermal material, such as one or more paramagnetic materials (e.g., iron, gadolinium, and their alloys). Additionally, braking system 59 can include a temperature sensor for measuring the temperature of the braking system, which can be coupled to brake 57. Braking system 59 can also include a braking unit that regulates the amount of braking force in response to an operator-requested braking event or a controller-initiated braking event. For example, during an operator-requested braking event, vehicle operator 130 can depress brake pedal 133. Brake pedal position sensor 135 can generate a proportional brake pedal position signal BPP, which can be used to determine the amount of braking force requested by the vehicle operator. For example, as the amount of depression of brake pedal 133 increases, the amount of braking force increases. The amount of braking force can include braking force and / or braking torque.

[0017] As described below with reference to Figure 2Further described, a magnetic field generator 60 may be included in the vehicle 5 for generating a magnetic field and applying the magnetic field to the braking system 59. In one example, the magnetic field generator 60 includes a permanent magnet and an electronic actuator for moving the permanent magnet closer to and farther from the braking system 59 to apply and withdraw the magnetic field applied to the braking system 59, respectively. In another example, the magnetic field generator 60 may be an electromagnet positioned such that the magnetic field generated by the magnetic field generator 60 when current is supplied to the magnetic field generator 60 is applied to the braking system 59. The strength of the magnetic field generated by the magnetic field generator 60 may be varied based on the properties of the (one or more) magnetocaloric materials of one or more components of the braking system 59 and the achievable proximity of the magnetic field generator 60 to one or more components of the braking system 59 that are at least partially composed of magnetocaloric materials. Additionally, the strength of the magnetic field generated by the magnetic field generator 60 may be limited based on potential electromagnetic interference. Further, as described further below, when magnetic fields are generated by the magnetic field generator 60 and any other magnetic field generators included in the vehicle 5, sensor signals (such as the signal or output of an oxygen sensor) may be compensated for such electromagnetic interference.

[0018] The electric motor 52 receives power from the traction battery 58 to provide torque to the wheels 55. The electric motor 52 can also operate as a generator to provide power to charge the battery 58, for example, during a braking operation.

[0019] The cylinders 14 of the engine 10 are capable of receiving intake air via a series of intake passages 142, 144, and 146. In addition to the cylinder 14, the intake passage 146 is also capable of communicating with other cylinders of the engine 10. In some examples, one or more of the intake passages may include a boosting device, such as a turbocharger or a supercharger. For example, Figure 1 An engine 10 configured with a turbocharger is shown, which includes a compressor 174 disposed between the intake passages 142 and 144 and an exhaust turbine 176 disposed along the exhaust passage 148. When the boosting device is configured as a turbocharger, the compressor 174 can be at least partially powered by the exhaust turbine 176 via a shaft 180. However, in other examples, such as when the engine 10 is provided with a supercharger, the compressor 174 can be powered by a mechanical input from a motor or the engine, and the exhaust turbine 176 can optionally be omitted.

[0020] A throttle valve 162 including a throttle plate 164 may be provided in the engine intake passage for changing the flow rate and / or pressure of the intake air supplied to the engine cylinders. For example, as Figure 1 shown, the throttle valve 162 may be positioned downstream of the compressor 174, or alternatively, may be provided upstream of the compressor 174.

[0021] In addition to cylinder 14, the exhaust passage 148 can also receive exhaust from other cylinders of the engine 10. The exhaust sensor 128 is shown as being coupled to the exhaust passage 148 upstream of the emission control device 178. The exhaust sensor 128 can be selected from various suitable sensors for providing an indication of the exhaust air-fuel ratio (AFR), such as a linear oxygen sensor or UEGO (universal or wide-range exhaust gas oxygen), a two-state oxygen sensor or EGO (as shown), a HEGO (heated EGO), a NOx, HC, or CO sensor. As described above, the exhaust sensor 128 and the remaining sensors included in the vehicle 5 can be affected by electromagnetic interference caused by the magnetic field(s) generated by the magnetic field generator(s) of the vehicle system. Accordingly, the output of the exhaust sensor 128 can be compensated when a magnetic field is applied. For example, the switching point of the sensor (e.g., the voltage at which the sensor switches from indicating a rich fuel condition to a lean fuel condition) can be shifted. In one example, the switching point can be shifted to a higher voltage when a magnetic field is applied. In an alternative example, the switching point can be shifted to a lower voltage when a magnetic field is applied. In yet another example, the sensor including the exhaust sensor 128 can be at least partially shielded from electromagnetic interference, such as by shielding components (e.g., wires) of the sensor within a location proximate the magnetic field generator(s).

[0022] The emission control device 178 can be a three-way catalyst, a NOx trap, various other emission control devices, or a combination thereof. In Figure 1 an example, the emission control device 178 is a three-way catalyst that includes a catalyst housing, which can also be referred to herein as an exhaust catalytic converter or simply a catalyst. In one example, the catalyst housing disposed proximate the catalyst is at least partially constructed of a magnetocaloric material, such as one or more paramagnetic materials (e.g., iron, gadolinium, and their alloys). In some examples, the exhaust passage 148 is additionally or alternatively constructed of a magnetocaloric material, which can be the same or different magnetocaloric material as the catalyst housing. For example, a portion of the exhaust passage 148 proximate the catalyst (e.g., directly upstream and / or downstream of and / or surrounding the catalyst) can be constructed of a magnetocaloric material.

[0023] As regarding Figures 2 - 3Further described, a magnetic field generator 62 can be included near the area of the catalyst 178 and the exhaust passage 148 to apply a magnetic field to the catalyst 178 and / or the exhaust passage 148. As described above for the magnetic field generator 60, the magnetic field generator 62 can be a permanent magnet or an electromagnet, and can be the same or a different type of magnetic field generator as the magnetic field generator 60. In an alternative example, the magnetic field generator 62 can be omitted, and the magnetic field generator 60 can apply a magnetic field to both the braking system 59 and the exhaust system components (e.g., the catalyst 178 and / or the exhaust passage 148). For example, the magnetic field generator 60 can be actuated to a position close to the braking system 59 to apply a magnetic field to the braking system 59 and can be actuated to a different position close to the exhaust system components to apply a magnetic field to the catalyst 178 and / or the exhaust passage 148.

[0024] Each cylinder of the engine 10 can include one or more intake valves and one or more exhaust valves. For example, cylinder 14 is shown as including at least one intake lift valve 150 and at least one exhaust lift valve 156 located in the upper region of cylinder 14. In some examples, each cylinder of the engine 10 (including cylinder 14) can include at least two intake lift valves and at least two exhaust lift valves located in the upper region of the cylinder. The intake valve 150 can be controlled by the controller 12 via the actuator 152. Similarly, the exhaust valve 156 can be controlled by the controller 12 via the actuator 154. The positions of the intake valve 150 and the exhaust valve 156 can be determined by respective valve position sensors (not shown).

[0025] During some conditions, the controller 12 can change the signals provided to the actuators 152 and 154 to control the opening and closing of the respective intake and exhaust valves. The valve actuators can be of the electric valve actuation type or the cam actuation type or a combination thereof. The intake valve timing and the exhaust valve timing can be controlled simultaneously, or any one of variable intake cam timing, variable exhaust cam timing, dual independent variable cam timing, or fixed cam timing can be used. Each cam actuation system can include one or more cams, and can utilize one or more of a cam profile switching (CPS), variable cam timing (VCT), variable valve timing (VVT), and / or variable valve lift (VVL) systems, which can be operated by the controller 12 to change the valve operation. For example, cylinder 14 can alternatively include an intake valve controlled by electric valve actuation and an exhaust valve controlled by cam actuation including CPS and / or VCT. In other examples, the intake and exhaust valves can be controlled by a common valve actuator (or actuation system) or a variable valve timing actuator (or actuation system).

[0026] Cylinder 14 can have a compression ratio that is the ratio of the volume when the piston 138 is at bottom dead center (BDC) to the volume when at top dead center (TDC). In one example, the compression ratio is in the range of 9:1 to 10:1. However, in some examples using different fuels, the compression ratio can be increased. For example, this can occur when using a higher octane fuel or a fuel with a higher latent heat of vaporization enthalpy. If direct injection is used due to its effect on engine knock, the compression ratio can also be increased.

[0027] In some examples, each cylinder of engine 10 can include a spark plug 192 for initiating combustion. The ignition system 190 can provide an ignition spark to the combustion chamber 14 via the spark plug 192 in a selected operating mode in response to a spark advance signal SA from the controller 12. The timing of the signal SA can be adjusted based on engine operating conditions and driver torque demand. For example, the spark can be provided at the maximum brake torque (MBT) timing to maximize engine power and efficiency. The controller 12 can input engine operating conditions including engine speed, engine load, and exhaust AFR into a lookup table and output the corresponding MBT timing for the input engine operating conditions. In other examples, the spark can be retarded from MBT to accelerate catalyst warm-up during engine start. The retarded spark timing is used to transfer more heat to the exhaust rather than occurring at the MBT timing, and then this heat can be transferred to the catalyst when processing the exhaust.

[0028] In some examples, each cylinder of engine 10 can be configured with one or more fuel injectors for supplying fuel thereto. As a non-limiting example, cylinder 14 is shown as including a fuel injector 166. The fuel injector 166 can be configured to deliver fuel received from the fuel system 8. The fuel system 8 can include one or more fuel tanks, fuel pumps, and a fuel rail. The fuel injector 166 is shown as being directly coupled to cylinder 14 to directly inject fuel into cylinder 14 in proportion to the pulse width of a signal FPW received from the controller 12 via an electronic driver 168. In this way, the fuel injector 166 provides what is referred to as direct injection of fuel (hereinafter also referred to as "DI"). Although Figure 1 the fuel injector 166 is shown positioned on one side of cylinder 14, the fuel injector 166 can alternatively be located at the top of the piston, such as in a position near the spark plug 192. Due to the lower volatility of some alcohol-based fuels, such a location can increase mixing and combustion when operating the engine with an alcohol-based fuel. Alternatively, the injector can be located at the top and near the intake valve to improve mixing. The fuel can be delivered from a fuel tank of the fuel system 8 to the fuel injector 166 via a high-pressure fuel pump and a fuel rail. Additionally, the fuel tank can have a pressure sensor that provides a signal to the controller 12.

[0029] In an alternative example, fuel injector 166 may be disposed in intake passage 146 rather than being directly coupled to cylinder 14, with fuel injector 166 in a configuration that provides so-called port fuel injection (hereinafter also referred to as "PFI") of fuel into the intake passage upstream of cylinder 14. In other examples, cylinder 14 may include multiple injectors, which may be configured as direct fuel injectors, port fuel injectors, or a combination thereof. Thus, it should be understood that the fuel systems described herein should not be limited to the specific fuel injector configurations described herein as examples.

[0030] Fuel injector 166 may be configured to receive different fuels from fuel system 8 as a fuel mixture in different relative amounts and further configured to directly inject the fuel mixture into the cylinder. Additionally, fuel may be delivered to cylinder 14 during different strokes of a single cycle of the cylinder. For example, the directly injected fuel may be delivered at least in part during a previous exhaust stroke, during an intake stroke, and / or during a compression stroke. Thus, for a single combustion event, one or more fuel injections may be performed per cycle. The multiple injections may be made during the compression stroke, the intake stroke, or any suitable combination thereof, such as split fuel injection.

[0031] The fuel tank in fuel system 8 may hold fuels of different fuel types, such as fuels having different fuel qualities and different fuel compositions. These differences may include different alcohol contents, different water contents, different octane ratings, different heat of vaporizations, different fuel blends, and / or combinations thereof, etc. An example of fuels having different heats of vaporization includes gasoline having a lower heat of vaporization as a first fuel type and ethanol having a greater heat of vaporization as a second fuel type. In another example, the engine may use gasoline as a first fuel type and an ethanol-containing fuel blend, such as E85 (which is approximately 85% ethanol and 15% gasoline) or M85 (which is approximately 85% methanol and 15% gasoline), as a second fuel type. Other viable substances include water, methanol, mixtures of ethanol and water, mixtures of water and methanol, mixtures of ethanol, etc. In yet another example, both fuels may be ethanol blends having different alcohol compositions, where the first fuel type may be a gasohol blend having a lower alcohol concentration, such as E10 (which is approximately 10% ethanol), while the second fuel type may be a gasohol blend having a higher alcohol concentration, such as E85 (which is approximately 85% ethanol). Additionally, the first fuel and the second fuel may also differ in other fuel qualities, such as differences in temperature, viscosity, octane rating, etc. Further, the fuel characteristics of one or both fuel tanks may vary frequently, for example due to daily variations in tank refilling.

[0032] Controller 12 is at Figure 1is shown as a microcomputer and includes a microprocessor unit (CPU) 106, input / output ports (I / O) 108, an electronic storage medium for executable programs (e.g., executable instructions) and calibration values shown as a non-transitory read-only memory chip (ROM) 110 in this particular example, a random access memory (RAM) 112, a keep-alive memory (KAM) 114, and a data bus. The controller 12 can receive various signals from sensors coupled to the engine 10, including the signals discussed previously and additionally including a measurement of intake mass air flow (MAF) from an air mass flow sensor 122; an engine coolant temperature (ECT) from a temperature sensor 116 coupled to the coolant jacket 118; an exhaust temperature from a temperature sensor 158 coupled to the exhaust passage 148; a surface ignition sensing signal (PIP) from a Hall effect sensor 120 (or other type) coupled to the crankshaft 140; a throttle position (TP) from a throttle position sensor; a signal EGO from an exhaust sensor 128, which can be used by the controller 12 to determine the AFR of the exhaust; and an absolute manifold pressure signal (MAP) from a MAP sensor 124. The engine speed signal RPM can be generated by the controller 12 from the signal PIP. The manifold pressure signal MAP from the MAP sensor 124 can be used to provide an indication of the vacuum or pressure in the intake manifold. The controller 12 can infer the engine temperature based on the engine coolant temperature and infer the temperature of the catalyst 178 based on the signal received from the temperature sensor 158.

[0033] The controller 12 receives signals from Figure 1 various sensors and employs Figure 1 various actuators to regulate engine operation based on the received signals and instructions stored in the controller's memory. For example, the controller can actuate the magnetic field generator 60 so as to cool the braking system 59 via MCE, as further described below with reference to Figure 2 In another example, the controller can delay the timing of the signal SA sent to the ignition system 190, thereby delaying the timing of the spark provided to the cylinder 14 by the spark plug 192, and / or actuate the magnetic field generator 62 so as to accelerate catalyst preheating when the temperature of the catalyst 178 is below its light-off temperature, as further described below with respect to Figures 2 - 3

[0034] As described above, Figure 1 ​Only one cylinder of a multi-cylinder engine is shown. Thus, each cylinder can similarly include its own set of intake / exhaust valves, fuel injector(s), spark plug, etc. It should be understood that engine 10 can include any suitable number of cylinders, including 2, 3, 4, 5, 6, 8, 10, 12, or more cylinders. Additionally, each of these cylinders can include some or all of the various components described and depicted by reference to cylinder 14 Figure 1 of some or all of the various components.

[0035] During vehicle operation, the temperature of the braking system (e.g., Figure 1 braking system 59) increases as the brakes (e.g., Figure 1 brakes 57) are applied to slow the rotation of the wheels. If the braking system becomes overheated, braking performance deteriorates. Thus, braking system cooling enables safe and effective braking. Additionally, as described above, vehicle emissions can increase before the exhaust catalytic converter (e.g., Figure 1 catalyst 178) reaches its light-off temperature. Thus, catalyst heating can be accelerated to reduce the time it takes for the catalyst to reach its light-off temperature, thereby reducing the overall emissions produced by the vehicle. Specifically, if one or more components of the braking system (e.g., brake rotor and / or brake pads) and one or more components of the exhaust system (e.g., the housing of the catalyst and / or the exhaust passage) are at least partially composed of magnetothermal material, applying a magnetic field to these selected components can be used in the process of ultimately cooling the braking system and / or heating the exhaust catalytic converter.

[0036] Figure 2 An example method 200 for thermally regulating a braking system and a catalyst by selecting components of the braking system or the catalyst via the application of a magnetic field is provided. The instructions for performing method 200 and the remaining methods included herein can be executed by a controller (e.g., Figure 1 controller 12) based on instructions stored in the controller's memory and in conjunction with signals received from sensors of the vehicle system (such as the sensors described above with reference to Figure 1 e.g., exhaust temperature sensor 158, temperature sensor of braking system 59). The controller can employ vehicle actuators of the engine and vehicle system (e.g., Figure 1 magnetic field generators 60 and 62) to regulate engine and vehicle operation according to the methods described below.

[0037] Method 200 begins at 202 and includes calculating and / or measuring vehicle operating conditions. Vehicle operating conditions can include vehicle operating mode (such as an electric mode where the vehicle is propelled by torque from an electric motor, or an engine mode where the vehicle is propelled at least in part by torque from an engine), driver-requested torque, engine speed and load, temperature of a catalyst, state of charge (SOC) of a system battery (e.g., Figure 1 traction battery 58), temperature of a braking system (e.g., as measured by a temperature sensor included in the braking system), and position of a brake pedal (e.g., a signal BPP output by a brake pedal position sensor such as Figure 1 the brake pedal position sensor 135 shown). For example, the temperature of the catalyst can be inferred based on exhaust temperature, where the controller inputs the exhaust temperature into a look-up table or mathematical function and outputs the temperature of the catalyst. In addition or alternatively, if a temperature sensor is not included in the braking system, for example, the duration of a braking event (e.g., the duration the brake pedal is depressed for each braking event) can be monitored and stored in the controller's memory, and then the stored value can be used to determine a standard magnetic field application duration.

[0038] At 204, it is determined whether the temperature of the catalyst (T cat ) is less than a first threshold temperature. In one example, the first threshold temperature can be the light-off temperature of the catalyst. As described above, operating with a catalyst below the light-off temperature can increase vehicle emissions, such as can occur during a cold engine start.

[0039] If the temperature of the catalyst is not below the first threshold temperature (or if the vehicle is operating in an electric mode where no catalyst is used), then method 200 proceeds to 206 and includes maintaining an engine setting. As shown at 208, maintaining the engine setting can include setting a spark timing for a requested (e.g., driver-requested) torque and optimal fuel economy. For example, the spark can be provided at or near MBT to maximize engine power for a given engine load. As shown at 210, maintaining the engine setting can also include not applying a magnetic field to one or more exhaust system components. For example, the controller can refrain from actuating a magnetic field generator (such as Figure 1 the magnetic field generator 62 shown) to apply a magnetic field to one or more exhaust system components. By not applying a magnetic field to one or more exhaust system components, the specific heat capacity of the catalyst does not change. For example, when the temperature of the catalyst is not below the first threshold temperature, there is no cold engine start condition, and thus engine control methods for accelerating catalyst heating (such as retarding spark timing and applying MCE) can instead reduce fuel economy and engine performance.

[0040] Conversely, if the temperature of the catalyst at 204 is less than the first threshold temperature, method 200 proceeds to 212 and includes accelerating catalyst heating via one or more of spark retard, staged fuel injection, and applying a magnetic field to one or more exhaust system components, as further described herein with respect to Figure 3 As described. In this manner, the amount of time for the catalyst to reach its light-off temperature can be reduced, thereby reducing overall vehicle emissions.

[0041] Regardless of whether the catalyst has reached its light-off temperature, at 214, it is determined whether a vehicle braking event exists (e.g., occurs). For example, a vehicle braking event can include the vehicle operator depressing the brake pedal (e.g., Figure 1 brake pedal 133) to request braking of the vehicle. In one example, depressing the brake pedal generates a signal BPP that is sent to the controller to actuate the braking system. In another example, depressing the brake pedal directly actuates the engagement of the brakes. In yet another example, in response to identifying an object in the vehicle's travel path (such as using data from one or more sensors, radar systems, and / or on-board cameras), the controller can actuate the braking system in a fully autonomous or semi-autonomous vehicle without input from the vehicle operator.

[0042] If no vehicle braking event exists, method 200 proceeds to 216 and includes maintaining the vehicle settings. Thus, the vehicle brakes will not engage. Additionally, a magnetic field will not be applied to one or more braking system components. For example, the controller may not actuate a magnetic field generator (such as Figure 1 magnetic field generator 60 shown) to apply a magnetic field to one or more braking system components. Thus, the application of the magnetic field is not used for braking system cooling. After 216, method 200 ends.

[0043] Conversely, if a vehicle braking event exists at 214, method 200 proceeds to 218 and includes engaging the vehicle brakes according to the braking demand. In one example, in response to the controller receiving the signal BPP generated from depressing the brake pedal or from one or more sensors, radar systems, and / or on-board cameras, the controller determines the amount of braking force and then sends a signal to the actuator of the brakes to adjust the braking force. In another example, the brakes are directly actuated by the brake pedal, where the braking force is proportional to the brake pedal position. For example, if the brakes are friction brakes, hydraulic brake fluid can then press the brake pads into the brake rotor in a manner proportional to the brake pedal position signal, thereby generating friction (and heat) between the brake pads and the brake rotor and slowing the wheels. The greater the degree to which the brake pedal is depressed, the greater the engagement between the brake pads and the brake rotor. Thus, during braking, the temperature of the braking system can increase.

[0044] At 220, it is determined whether the braking event is complete. For example, the braking event may be complete when the vehicle operator no longer presses the brake pedal and / or the controller no longer actuates the braking system to engage the brakes. If the braking event is not complete (e.g., the brakes remain engaged), the method may return to 218 and continue to engage the vehicle brakes according to the braking demand as described above.

[0045] If the braking event is complete (e.g., the brakes are no longer engaged), the method 200 proceeds to 222 and includes applying a magnetic field to one or more braking system components that are at least partially composed of a magneto-thermal material (e.g., brake pads and / or brake rotors). The magnetic field can be applied via a magnetic field generator that is positioned such that the magnetic field generated by the magnetic field generator reaches the one or more braking system components. For example, if the magnetic field generator is a permanent magnet, applying the magnetic field to the one or more braking system components (e.g., brake pads and / or brake rotors) may include the controller actuating an actuator to move the permanent magnet to a position where the magnetic field generated by the permanent magnet is applied to the one or more braking system components when the permanent magnet is within a threshold distance from the braking system components (e.g., within a range of 0 to 24 inches). The threshold distance can be a pre-calibrated value based on the magnetic field strength of the permanent magnet, where the threshold distance decreases as the magnetic field strength decreases. In another example, if the magnetic field generator is an electromagnet, applying the magnetic field to the one or more braking system components may include the controller causing current to flow through the electromagnet, which can be positioned close to (one or more) braking system components (within a threshold distance from or closer to the braking system components including magneto-thermal material compared to the exhaust system components including magneto-thermal material). In some embodiments, there may be one magnetic field generator for each brake (e.g., for each wheel of the vehicle), or there may be multiple magnetic field generators for each brake. For example, the (one or more) magnetic field generators can be positioned at or around the center of the wheel hub. In another example, the (one or more) magnetic field generators can be positioned behind the brake rotor. In yet other examples, if permanent magnets are used, the (one or more) magnetic field generators can be mounted on a bracket located outside the vehicle's chassis or outside the braking system, such as a movable (e.g., rotatable, slidable) bracket.

[0046] When a magnetic field is applied to one or more brake system components, the magnetic domains of the one or more brake system components that are at least partially composed of a magnetocaloric material will align with the applied magnetic field, thereby reducing the specific heat capacity of the magnetocaloric material (and thus the specific heat capacity of the entire brake system). Initially, this causes the temperature of the magnetocaloric material to further increase. However, compared to when no magnetic field is applied, the magnetocaloric material dissipates heat to its (cooler) surroundings more quickly via both convective heat transfer and radiative heat transfer, thereby increasing the overall cooling rate of the brake system. For example, the convective heat transfer rate is proportional to the temperature difference between an object (such as the brake system) and its surrounding fluid (such as ambient air). Since applying the magnetic field initially raises the temperature of the magnetocaloric material of the one or more brake system components, the convective heat transfer rate increases. Similarly, the radiative heat transfer rate is proportional to the absolute temperature of the object. Therefore, the increase in temperature also increases the radiative heat transfer rate. Additionally, with the decrease in specific heat capacity, less heat is dissipated from the magnetocaloric material of the brake system for a given temperature decrease compared to when the specific heat capacity is larger (such as when no magnetic field is applied).

[0047] Additionally, when a magnetic field is applied, electromagnetic interference can affect sensor readings, such as the output of an exhaust sensor (e.g., Figure 1 the exhaust sensor 128). Therefore, as further described above with reference to Figure 1 the sensor readings can be compensated (e.g., corrected) when a magnetic field is applied, such as by shifting the switching point of the exhaust sensor.

[0048] At 224, it is determined whether a magnetic field deactivation condition is satisfied. The magnetic field deactivation condition can include that the brake system temperature is less than a threshold temperature, a threshold duration is satisfied, the battery SOC is less than a threshold SOC, and the application of the brake is engaged (e.g., as described at 214). If one or more of the magnetic field deactivation conditions exist, the magnetic field deactivation condition can be considered satisfied. The threshold temperature can define a temperature at which the brake system is considered to be sufficiently cooled. The threshold temperature can be a non-zero threshold, but can be lower than the temperature of the brake system components immediately following a braking event. For example, once the threshold temperature is reached, it can be expected that the brake system will operate nominally or effectively during subsequent braking events. Similarly, the threshold duration can define a duration after which the brake system is predicted to be sufficiently cooled (e.g., cooled to the threshold temperature), and this duration can be the standard magnetic field application duration (e.g., determined at 202 based on the stored braking event duration). Since the strength of the applied magnetic field affects the temperature change of the magnetocaloric material (e.g., as the strength of the magnetic field increases, the magnetocaloric material experiences a greater temperature change), the threshold duration can be determined by the controller based on the strength of the applied magnetic field. For example, the controller can refer to a look-up table with the strength of the magnetic field, the starting temperature of the brake system, and the ambient temperature as inputs and output the threshold duration. Thus, the threshold duration can vary based on the operating conditions. In one example, as the strength of the applied magnetic field increases, the threshold duration can decrease. Since applying the magnetic field can use energy from the vehicle battery, such as by supplying current to an electromagnet or moving a permanent magnet with an electronic actuator, the threshold SOC can be the battery charge state level below which the battery may not be able to support or perform additional vehicle functions (such as operating the vehicle in an electric mode). In this way, the applied magnetic field can be deactivated before the battery SOC drops below the threshold SOC, thereby conserving an amount of battery life for powering additional vehicle functions or systems. Additionally, applying a magnetic field during braking can cause the brake system to heat up faster.

[0049] If the magnetic field deactivation condition is satisfied, method 200 proceeds to 226 and includes deactivating the magnetic field applied to the brake system components. For example, if the magnetic field generator is a permanent magnet, deactivating the magnetic field applied to the brake system components can include actuating an actuator that adjusts the position of the permanent magnet such that the permanent magnet is moved to a distance at which the magnetic field generated by the permanent magnet no longer reaches the magnetocaloric material of one or more brake system components. In another example, if the magnetic field generator is an electromagnet, deactivating the magnetic field applied to the brake system components can include causing current to no longer flow through the electromagnet. When the magnetic field is no longer applied to the brake system components, the magnetic domains of the magnetocaloric material become disordered due to the thermal energy in the material, thereby absorbing energy and further reducing the temperature of the material (and the entire brake system). Thus, by applying a magnetic field to the (one or more) brake system components, heat dissipates more quickly and the brake system can reach a lower temperature than when the magnetic field is not applied to the (one or more) brake system components. After 226, method 200 ends.

[0050] If the magnetic field deactivation condition is not satisfied at 224 (e.g., the brake system temperature is not less than the threshold temperature, the threshold duration has not been met, the battery SOC is not less than the threshold SOC, and the brakes are not applied), method 200 proceeds to 228 and includes continuing to apply the magnetic field to one or more brake system components. Thus, the brake system continues to cool more quickly than when the magnetic field is not applied to the one or more brake system components. After 228, method 200 ends.

[0051] Thus, Figure 2 A method is provided for thermally regulating an exhaust catalyst and a brake system of a vehicle using the application of a magnetic field to one or more exhaust system and brake system components, the brake system components being at least partially composed of magnetocaloric material. The application of the magnetic field affects the heat transfer rate to or from components that are at least partially composed of magnetocaloric material. The direction of heat transfer depends on the temperature of the component relative to its surroundings. Since the ambient air is cooler than the brake system, the application of the magnetic field causes heat to transfer out of the brake system more quickly than when the magnetic field is not applied. Continuing to refer Figure 3 to, in an example of method 300, the application of a magnetic field for catalyst heating will be explained, which method can be used alone or in combination with additional strategies for accelerating catalyst heating. Figure 3 Can be performed by a controller that is part of Figure 2 method 200 in

[0052] Method 300 begins at 302 and includes determining a spark retard timing for increased catalyst heating. Retarding the spark timing (e.g., by a spark plug such as Figure 1The timing during the engine cycle at which the spark plug 192 provides the ignition spark) can increase the exhaust temperature due to combustion occurring later in the engine cycle. The increased exhaust temperature can provide additional heat transfer to the catalyst, thereby accelerating catalyst heating. Thus, as further described herein, the spark retard timing can be determined as a fixed number of crankshaft angle degrees retarded from MBT, where MBT is based on engine operating conditions (e.g., as measured at 202 of Figure 1 as further described). Figure 2 is determined at 202).

[0053] At 304, it is determined whether the temperature of the catalyst is below a second threshold temperature, which is lower than the first threshold temperature (e.g., as described at 204 of Figure 2 as further described). The second threshold temperature can be a threshold amount below the light-off temperature, which can indicate that the catalyst is particularly cold, such as can occur during cold weather conditions (e.g., during winter), which can further increase the amount of time it takes for the catalyst to reach its light-off temperature. For example, when the catalyst temperature is below the second threshold temperature, the time it takes for the catalyst to reach the light-off temperature can result in degraded emissions and / or reduced engine efficiency. Thus, if the temperature of the catalyst is below the second threshold temperature, a more aggressive catalyst heating strategy (such as by combining multiple catalyst heating methods) can be beneficial.

[0054] If the temperature of the catalyst is less than a second threshold temperature, method 300 proceeds to 306 and includes setting the spark timing at the determined spark retard timing (e.g., as determined at 302), delivering fuel via split injection, and applying a magnetic field to one or more exhaust system components (such as the housing of the catalyst and / or the exhaust manifold proximate the catalyst, each at least partially composed of a magnetocaloric material). Delivering a spark at the determined spark retard timing can increase the exhaust temperature, but it can also reduce combustion stability, leading to an increased incidence of misfires. Thus, fuel can be delivered via split injection, where a first larger portion of fuel is delivered during the intake stroke to facilitate charge mixing, and a second remaining portion is delivered via one or more injections during the compression stroke. The (one or more) compression stroke injections contribute to combustion stability by providing a rich pocket of air-fuel mixture near the spark plug. The magnetic field can be applied via a magnetic field generator that is positioned such that the magnetic field generated by the magnetic field generator reaches one or more exhaust system components composed of magnetocaloric material. For example, if the magnetic field generator is a permanent magnet, applying a magnetic field to one or more exhaust system components can include the controller actuating an actuator to move the permanent magnet to a position where the magnetic field generated by the permanent magnet is applied to one or more exhaust system components. If the magnetic field generator is an electromagnet, applying a magnetic field to one or more exhaust system components can include the controller causing current to flow through the electromagnet, which can be proximate (such as within a threshold distance of (one or more) exhaust system components (e.g., in the range of 0 - 24 inches)) (one or more) exhaust system components. In one example, the electromagnet is mounted around an exhaust component, such as a solenoid having an exhaust passage and / or a catalyst housing extending through a hollow cylindrical interior of the electromagnet).

[0055] When a magnetic field is applied to one or more exhaust system components, the magnetic domains of the magnetocaloric material included in the (one or more) exhaust system components will align with the applied magnetic field, thereby reducing the specific heat capacity of the magnetocaloric material and causing the temperature of the magnetocaloric material to increase as magnetic entropy is converted into thermal energy. Additionally, as hot exhaust flows over the magnetocaloric material, the heat transferred from the exhaust to the magnetocaloric material will result in a greater increase in temperature due to the reduced specific heat capacity of the magnetocaloric material. Further, the increase in exhaust temperature resulting from operating at a retarded spark timing will cause more heat to be transferred from the engine to the exhaust system components, resulting in an even greater increase in the temperature of the magnetocaloric material than when using MCE alone (or when using spark retard alone).

[0056] Additionally, when a magnetic field is applied, electromagnetic interference can affect sensor readings, such as the output of an exhaust sensor (e.g., Figure 1 the exhaust sensor 128). Thus, as referenced above Figure 1Further described, the sensor readings can be compensated when a magnetic field is applied, such as by shifting the switching point of the exhaust sensor.

[0057] If, instead, the temperature of the catalyst at 304 is not lower than a threshold temperature (e.g., as Figure 2 described at 204, the temperature of the catalyst is lower than a first threshold temperature and greater than or equal to a second threshold temperature), then method 300 proceeds to 308. At 308, method 300 includes determining the energy and fuel economy losses of operating the engine at a determined spark retard timing, which can be referred to as a first loss (Loss 1). For example, the controller can convert the fuel economy loss to a unitless value based on the reduced engine torque ratio corresponding to the determined retarded spark timing. That is, for the same amount of fuel delivered, operating at a retarded spark timing will produce less engine torque compared to operating at MBT spark timing. For example, the controller can refer to a look-up table or map to determine the reduced engine torque ratio that will be produced by the determined retarded spark timing. Operating at the determined retarded spark timing may have no energy loss (e.g., does not consume additional energy). Thus, as described below, the first loss can be the fuel economy loss for providing spark at a retarded timing, which is converted to a unitless value for comparison with the energy loss.

[0058] At 310, method 300 includes determining the energy and fuel economy losses of generating and applying a magnetic field to an exhaust system component, which can be referred to as a second loss (Loss 2). For example, applying the magnetic field can use power from a battery (e.g., Figure 1the traction battery 58) or the energy of the vehicle powertrain, such as by supplying current to an electromagnet or moving a permanent magnet with an electronic actuator, resulting in energy losses. Additionally, in some examples, if the energy used to increase fuel economy of the vehicle system (e.g., such as by operating in an electric mode) is instead used to apply a magnetic field to one or more exhaust system components, fuel economy can be reduced. Thus, the controller can estimate the amount of energy consumed by generating a magnetic field and applying the magnetic field to the (one or more) exhaust system components. As an example, if the magnetic field generator is an electromagnet, the controller can estimate the amount of energy based on the temperature difference between the temperature of the catalyst and a first threshold temperature, the exhaust temperature, and the strength of the magnetic field to be generated. For example, the controller can input the temperature difference, the exhaust temperature, and the strength of the magnetic field to be generated into a look-up table or an equation and output the estimated amount of energy. As another example, if the magnetic field generator is a permanent magnet, the controller can estimate the amount of energy based on the energy supplied to the electronic actuator to move the permanent magnet from a starting position to a position where the magnetic field generated by the permanent magnet is applied to one or more exhaust system components and then back to the starting position. For example, the energy supplied to the electronic actuator to move the permanent magnet can be a known calibration value stored in the memory of the controller. If applicable, the fuel economy loss can be determined as the fuel economy loss associated with not driving the vehicle system to improve fuel economy. The controller can convert both the fuel economy loss and the energy loss into dimensionless values, and these dimensionless values are added together to determine a second loss. As an example, when generating a magnetic field and applying it to the (one or more) exhaust system components, such as when the fuel economy loss is zero or near zero, the second loss can be dominated by the energy loss of operating the engine.

[0059] At 312, it is determined whether the second loss is less than the first loss. That is, it is determined whether the loss of generating a magnetic field and applying it to the (one or more) exhaust system components to change the specific heat capacity of the catalyst is less than the loss of increasing the exhaust temperature via spark retard.

[0060] If the second loss is less than the first loss, the method 300 proceeds to 314 and includes applying a magnetic field to one or more exhaust system components while maintaining the spark timing of the requested engine torque at the optimal fuel economy. For example, the spark timing can be maintained at or near MBT. In another example, the spark timing can be nominally adjusted in response to other engine operating conditions (e.g., retarded in response to the occurrence of knock), but not adjusted for the purpose of catalyst heating. As described above, applying a magnetic field to one or more exhaust system components can include (via an actuator) moving a permanent magnet such that the magnetic field generated by the permanent magnet reaches the (one or more) exhaust system components or causing current to flow through an electromagnet.

[0061] At 312, if the second loss is not less than the first loss, method 300 proceeds to 316 and includes setting the spark timing to the determined spark retard timing and delivering fuel via staged injection, as described above at 306. A magnetic field is not applied to the exhaust system component(s), and catalyst heating will be accelerated via spark retard rather than by using a magnetic field.

[0062] At 318, it is determined whether the temperature of the catalyst is greater than or equal to a first threshold temperature. For example, a catalyst reaching the first threshold temperature may indicate that the catalyst has reached its light-off temperature. Thus, when the catalyst reaches the first threshold temperature, it may be hot enough to effectively process the exhaust and reduce vehicle emissions.

[0063] If the temperature of the catalyst is not greater than or equal to the first threshold temperature, method 300 proceeds to 320 and includes maintaining an accelerated catalyst heating strategy. Maintaining the accelerated catalyst heating strategy may optionally include maintaining a retarded spark timing and fuel delivery via staged injection, as shown at 322, and continuing to apply a magnetic field to the exhaust system component, as shown at 324. For example, if the spark timing is retarded, fuel is delivered via staged injection, and a magnetic field is applied for accelerated catalyst heating (e.g., as at 306), all three parameters may be maintained. In another example, if a magnetic field is applied to accelerate catalyst heating without adjusting the spark timing and fuel delivery (e.g., as at 314), the magnetic field may be maintained while the spark timing and fuel delivery continue to be adjusted nominally. In a further example, if the spark timing is retarded and fuel is delivered via staged injection for catalyst heating without a magnetic field being applied (e.g., as at 316), the spark timing will continue to be retarded and fuel will be delivered via staged injection without a magnetic field being applied. In this way, the accelerated catalyst heating may continue using an appropriate method. After 320, method 300 ends.

[0064] If the temperature of the catalyst is greater than or equal to the first threshold temperature, the catalyst can operate at its optimal temperature, such that the strategy does not have to accelerate catalyst heating. Accordingly, method 300 proceeds to 326 and includes stopping the accelerated catalyst heating. If a retarded spark timing is used to accelerate catalyst heating (e.g., at 306 and 316), stopping the accelerated catalyst heating can optionally include setting the spark timing for the requested engine torque and optimal fuel economy, as shown at 328. For example, the spark can be provided at or near MBT in order to maximize engine power for a given engine load rather than at the retarded timing determined for the accelerated catalyst heating. If MCE is used to reduce the specific heat capacity of one or more exhaust system components (e.g., at 306 and 314), then as shown at 330, stopping the accelerated catalyst heating can optionally include deactivating the magnetic field at a controlled rate. Deactivating the magnetic field at a controlled rate can include reducing the magnetic field from a fully applied field to a non-applied field over a duration that is not instantaneous at a set rate (e.g., a ramp rate or slope), such that the temperature of the catalyst remains at or above the first threshold temperature. For example, the controller can use a look-up table having the intensity of the applied magnetic field, the exhaust temperature, and the mass of the catalyst as inputs to determine the rate and output the rate. The controller can then reduce the intensity of the magnetic field according to the determined rate such that no magnetic field is applied at the end of the duration. Additionally, if additional sensors are included, such as a catalyst temperature sensor and / or an exhaust sensor coupled downstream of the catalyst, the output of the additional sensor(s) can be used as feedback for adjusting the duration and the controlled rate. For example, if the downstream exhaust sensor indicates low catalyst efficiency, such as by measuring high concentrations of hydrocarbons and / or NOx, the determined rate can be reduced (and the duration increased) such that the magnetic field remains applied to one or more exhaust system components for a longer duration. As another example, if the catalyst temperature sensor indicates that the catalyst temperature is a threshold amount above the first threshold temperature, the determined rate can be increased (and the duration decreased) such that the intensity of the magnetic field applied to one or more exhaust system components is reduced more quickly.

[0065] As an example, if the magnetic field generator is a permanent magnet, the controller can generate a control signal that is sent to an actuator of the permanent magnet to gradually move the permanent magnet away from the (one or more) exhaust system components at a rate corresponding to a desired rate of decrease in the magnetic field applied to the (one or more) exhaust system components. As another example, if the magnetic field generator is an electromagnet, the controller can decrease the amount of current flowing to the electromagnet at a rate corresponding to a desired rate of decrease in the magnetic field applied to the (one or more) exhaust system components. As the magnetic field decreases, the magnetic domains of the magneto-thermal material of the (one or more) exhaust system components become randomly oriented from the external magnetic field due to the thermal energy present in the (one or more) exhaust system components, which increases the ability of the (one or more) exhaust system components to store thermal energy (e.g., the specific heat capacity increases and more heat transfer is required for a temperature change). If the (one or more) exhaust system components are thermally isolated, the temperature can drop; however, due to the flow of hot exhaust through the exhaust system and the controlled rate of magnetic field deactivation, the temperature of the (one or more) exhaust system components can be maintained. After 326, method 300 ends.

[0066] Thus, in one example, method 300 may include determining a temperature of a catalyst and a spark retard timing for increasing heating of the catalyst. The method may further include determining a first loss and a second loss, the first loss being an energy and fuel economy loss for operating at the determined spark retard timing, and the second loss being an energy and fuel economy loss for generating a magnetic field and applying the magnetic field to one or more exhaust system components that are proximate to the catalyst and at least partially made of a magnetothermal material. In response to a first condition in which the second loss is less than the first loss and the temperature of the catalyst is less than a first threshold temperature and greater than a second threshold temperature, the magnetic field is applied to (e.g., via a magnetic field generator) the one or more exhaust system components while providing a spark at or near MBT timing. In response to a second condition in which the second loss is greater than or equal to the first loss and the temperature of the catalyst is less than the first threshold temperature and greater than the second threshold temperature, the spark timing is retarded from MBT timing, fuel is delivered via staged injection, and the magnetic field is not applied to the one or more exhaust system components. In response to a third condition in which the temperature of the catalyst is less than the second threshold temperature and regardless of the first loss and the second loss, the magnetic field is applied to the one or more exhaust system components, the spark timing is retarded from MBT timing, and fuel is delivered via staged injection. In response to none of the first, second, or third conditions existing, such as when the temperature of the catalyst is greater than or equal to the first threshold temperature, a spark is provided at or near MBT timing and the magnetic field is not applied to the one or more exhaust system components. In some examples, application of the magnetic field to the one or more exhaust system components occurs when the first or third condition exists and the second condition does not exist. Additionally, operation with a retarded spark timing and fuel delivered via staged injection occurs when the second or third condition exists and the first condition does not exist. Additionally, operation with a spark timing at or near MBT timing occurs when the second and third conditions do not exist and / or in or during the first condition.

[0067] Additionally, the instructions stored in the memory may include estimating the catalyst temperature based on the output of an exhaust temperature sensor (e.g., Figure 1 exhaust temperature sensor 158). The catalyst temperature may then be used to determine whether the third condition exists. Additionally, the catalyst temperature may be used with the first and second losses to determine whether the first or second condition exists. In response to the first or third condition existing, application of the magnetic field may be performed by instructions for sending a signal to actuate the magnetic field generator, and the spark timing may be set at or near MBT timing by instructions for sending a signal SA to an ignition system (e.g., Figure 1 ignition system 190) at or near MBT timing. In response to the second or third condition existing, the spark may be sent to the ignition system (e.g., Figure 1Instructions to send signal SA to the ignition system 190) are provided at a retarded spark timing, and fuel can be delivered via staged injection by instructions to send signal FPW to a fuel injector (e.g., Figure 1 the fuel injector 166). In some examples, the method can include determining whether to perform each of applying a magnetic field to one or more exhaust system components, providing a spark at a retarded spark timing, and delivering fuel via staged injection based on a determination of whether a first condition exists, a determination of whether a second condition exists, and a determination of whether a third condition exists.

[0068] Figure 4 An example graph 400 is shown of using an applied magnetic field to thermally condition components of a vehicle system during vehicle operation. The temperature of a catalyst (e.g., Figure 1 the catalyst 178) is shown in curve 402, the spark timing is shown in curve 404, the state of charge of a system battery (e.g., Figure 1 the traction battery 58) is shown in curve 406, the temperature of a braking system (e.g., Figure 1 the braking system 59) is shown in curve 408, the amount of braking force is shown in curve 410, applying a magnetic field to an exhaust system component is shown in curve 412 (solid line), and applying a magnetic field to a braking system component is shown in curve 414 (dashed line). Additionally, a first threshold temperature of the catalyst is indicated at T1, a second threshold temperature of the catalyst is indicated at T2, a threshold temperature of the braking system is indicated at T3, and a threshold SOC for transitioning from an electric operation mode (where torque from an electric motor (such as Figure 1 the electric machine 52) is used only to propel the vehicle) to an engine operation mode (where torque from an engine (such as Figure 1 the engine 10) is used to propel the vehicle) is indicated by dashed line 416. The MBT spark timing is also shown. In Figure 4 the example, the MBT spark timing is shown as a straight line. However, it should be understood that, as described with reference to Figure 1 , the MBT spark timing varies based on engine operating conditions. For all of the above cases, the X-axis represents time, where time increases along the X-axis from left to right. The Y-axis represents each marked parameter, whose value increases from bottom to top, except for curve 404, where the spark timing is advanced or retarded relative to MBT.

[0069] Just before time t1, the engine starts. Initially, the engine operates with a spark timing near MBT. In response to the temperature of the catalyst (curve 402) being less than a second threshold temperature T2, at time t1, the spark timing is retarded from MBT (curve 404) to increase the exhaust temperature, and a magnetic field is applied to one or more exhaust system components (such as the housing of the catalyst) that are at least partially composed of a magnetocaloric material (curve 412) to reduce the specific heat capacity of the (one or more) exhaust system components. The magnetic field can be applied by a magnetic field generator (such as Figure 1 magnetic field generator 62) located near the (one or more) exhaust system components. Since magnetic entropy is converted into heat energy when the magnetic field in the magnetocaloric material is aligned by an external magnetic field, the temperature of the catalyst first increases rapidly (curve 402). Then, as heat from the hot exhaust is transferred to the catalyst, the temperature of the catalyst continues to increase steadily, where the heat transfer rate decreases as the temperature of the catalyst approaches the exhaust temperature. Due to the reduction in the specific heat capacity of the (one or more) exhaust system components and the increase in the exhaust temperature, the temperature of the catalyst (curve 402) rises faster compared to if the magnetic field is applied without using spark retard (dashed line segment 402b) and if spark retard is used without MCE (dashed line segment 402c). By combining the two strategies, the catalyst reaches a first threshold temperature T1 at time t2, and the first threshold temperature T1 can be the light-off temperature of the catalyst. Applying the magnetic field has an energy loss, thereby reducing the battery SOC (curve 406). However, when driving the vehicle, the battery can be recharged.

[0070] In response to the catalyst reaching the first threshold temperature T1 at time t2 (which can be the light-off temperature of the catalyst), the magnetic field applied to the (one or more) exhaust system components decreases at a gradual and controlled rate (e.g., from "on" meaning full strength to "off" meaning no magnetic field applied). In this way, since the magnetic domains of the magnetocaloric material in the (one or more) exhaust system components become disordered by converting heat energy into magnetic entropy, the temperature of the catalyst can be maintained above the first threshold temperature T1. Additionally, at time t2, in response to the catalyst reaching its light-off temperature, the spark timing returns to MBT (curve 404).

[0071] At time t3, a vehicle braking event occurs, as indicated by an increase in the amount of braking force (curve 410). Due to the heat generated by friction when the amount of braking force is applied during brake engagement, the temperature of the braking system increases (curve 408). When the vehicle braking event is completed at time t4 (e.g., no braking force is requested), a magnetic field is applied to one or more braking system components (curve 414) that are at least partially composed of a magnetocaloric material (such as a brake rotor) to reduce the specific heat capacity of the (one or more) braking system components. The magnetic field can be applied by a magnetic field generator (such asFigure 1 is applied by the magnetic field generator 60). When the magnetic field of the magnetocaloric material is aligned by an external magnetic field, the temperature of the braking system initially increases (curve 408) because the magnetic entropy is converted into heat energy. However, due to the large temperature difference between the braking system and the surrounding environment, heat dissipates from the braking system at a faster rate compared to when the magnetic field is not applied to the (one or more) braking system components (dashed segment 408b), where the heat transfer rate decreases as the temperature of the braking system becomes closer to the temperature of the surrounding environment. Additionally, due to the decrease in the specific heat capacity of the magnetocaloric material, the temperature of the braking system (curve 408) decreases faster than the temperature without using MCE (dashed segment 408b).

[0072] At time t5, a second vehicle braking event occurs (curve 410). In response to a braking request, the magnetic field applied to the (one or more) braking system components is deactivated (curve 414). Since the magnetic domains of the magnetocaloric material in the (one or more) braking system components convert heat energy into magnetic entropy as they become randomly oriented, the temperature of the braking system temporarily decreases but then increases due to the heat generated by braking (curve 408). However, if MCE is not used, the braking system will start at a higher temperature, resulting in a higher maximum temperature during the braking event (dashed segment 408b). Note that in other examples, when the magnetic field applied to the (one or more) braking system components is deactivated, the temperature of the braking system may not decrease due to the heat generated by braking and the speed at which the magnetocaloric material responds to the magnetic field change; instead, the temperature of the braking system may initially increase by a small amount compared to if the magnetic field had not been applied before the braking event.

[0073] When the second vehicle braking event is completed at time t6, the magnetic field is again applied to the (one or more) braking system components (curve 414), resulting in a similar initial increase in temperature followed by a steady decrease in temperature (curve 408). At time t7, the braking system reaches the threshold temperature T3, indicating that the braking system is cold enough. In response to the braking system reaching the threshold temperature T3, the magnetic field applied to the (one or more) braking system components is turned off (curve 414). As the magnetic field becomes randomly oriented, the temperature of the braking system further decreases (curve 408). If MCE has not been used to enhance braking system cooling, the braking system will take longer to reach the threshold temperature T3 (dashed segment 408b). However, the battery SOC may decrease each time the magnetic field is applied (curve 406).

[0074] At time t8, as the vehicle transitions to an electric operation mode, the engine is turned off. For example, the electric operation mode may be selected to conserve fuel (e.g., the amount of fuel in the vehicle's fuel system is less than a threshold amount). In the electric operation mode, combustion does not occur and thus spark is disabled (curve 404). In the absence of a hot exhaust pre - heated catalyst, the temperature of the catalyst decreases (curve 402) and drops below a first threshold temperature T1. However, in the case where the catalyst is not in use, the controller may choose not to maintain the catalyst above its light - off temperature (and thus, no magnetic field is applied to the catalyst even if the catalyst temperature drops below the first threshold temperature T1).

[0075] When the vehicle is operating in the electric operation mode, the battery SOC decreases (curve 406). In response to the state of charge of the battery reaching a threshold battery SOC (dashed line 416) at time t9, the engine restarts. As described above with reference to Figure 3 the controller determines a catalyst heating strategy by comparing the loss of using a magnetic field (e.g., fuel economy / energy loss) with the loss of using spark retard to heat the catalyst (e.g., fuel economy / energy loss) since the temperature of the catalyst is less than the first threshold temperature T1. In response to the fuel economy / energy loss of generating and operating a magnetic field being less than the fuel economy / energy loss of retarding the spark, a magnetic field is selected for accelerating catalyst heating and thus, when the spark timing is set near MBT (curve 404), a magnetic field is applied to the exhaust system component(s) (curve 412). The temperature of the catalyst rises rapidly (curve 402). In response to the temperature of the catalyst reaching the first threshold temperature T1 at time t10, the magnetic field applied to the exhaust system component(s) decreases at a controlled rate (curve 412), which in Figure 4 the example is the same rate as between times t2 and t3. However, in other examples, the rate may vary between multiple catalyst heating events, where the rate is determined based on the intensity of the applied magnetic field, the exhaust temperature, and the mass of the catalyst, as described above with reference to Figure 3 Therefore, when the engine is operating, the catalyst is maintained above its light - off temperature.

[0076] In this way, by including magnetocaloric materials in one or more exhaust system components (e.g., the housing of an exhaust catalyst) and one or more brake system components (e.g., a brake rotor) as well as a magnetic field generator, the application of a magnetic field can be used for thermal regulation of the exhaust catalyst and the brake system. Depending on the direction of heat transfer, the application of the magnetic field can be used for both heating and cooling. In the case of the exhaust catalyst, heat is transferred from the exhaust to the catalyst. In the case of the brake system, heat is transferred from the brake system to the ambient air. When the magnetic domains of the magnetocaloric material included in one or more exhaust system components are aligned by the magnetic field applied by the magnetic field generator, the temperature of the catalyst rises more quickly, thereby reducing the amount of time before the catalyst reaches its light-off temperature, and thus reducing vehicle emissions. Applying a magnetic field to the (one or more) exhaust system components can be used alone or in combination with other catalyst heating strategies (such as spark retard). If spark retard is replaced and a magnetic field is applied to the magnetocaloric material of the (one or more) exhaust system components, engine torque and fuel efficiency can be increased. When the magnetic domains or magnetocaloric material included in one or more brake system components are aligned by the magnetic field applied by the magnetic field generator, the temperature of the brake system drops more rapidly and reaches a colder temperature than can be achieved without applying the magnetic field, thereby preventing the brake system from deteriorating due to high temperatures. By applying a magnetic field to the magnetocaloric material of the (one or more) brake system components for increasing heat dissipation rather than, for example, increasing the size of the brake rotor, the vehicle mass can be reduced.

[0077] The technical effect of applying a magnetic field to an exhaust catalytic converter at least partially composed of a magnetocaloric material is that the temperature of the exhaust catalytic converter rises at a faster rate.

[0078] As an example, a method for an engine is provided that includes: in response to the temperature of an exhaust catalytic converter being below a first threshold temperature, applying a magnetic field to an exhaust system component disposed proximate to the exhaust catalytic converter; and in response to the temperature rising to or above the first threshold temperature, stopping the application of the magnetic field. In the previous example, additionally or optionally, applying the magnetic field to the exhaust system component is further in response to the fuel economy and energy loss of generating and applying the magnetic field to raise the temperature of the exhaust catalytic converter to the first threshold temperature being less than the fuel economy and energy loss of adjusting an alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature. In any or all of the foregoing examples, additionally or optionally, adjusting the alternative engine operating parameter includes delaying the spark timing of the spark plugs of one or more engine cylinders. In any or all of the foregoing examples, the method additionally or optionally further includes delivering fuel to one or more engine cylinders via split injection while delaying the spark timing. In any or all of the foregoing examples, the method additionally or optionally further includes, in response to the temperature being below the first threshold temperature and the fuel economy and energy loss of generating and applying the magnetic field to raise the temperature of the exhaust catalytic converter to the first threshold temperature being greater than the fuel economy and energy loss of adjusting an alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature, adjusting the alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature instead of applying the magnetic field to the exhaust system component. In any or all of the foregoing examples, the method additionally or optionally further includes, in response to the temperature being below a second threshold temperature lower than the first threshold temperature, delaying the spark at one or more engine cylinders and performing split fuel injection at one or more engine cylinders while applying the magnetic field to the exhaust system component. In any or all of the foregoing examples, additionally or optionally, the first threshold temperature is the light-off temperature of the exhaust catalytic converter, and the application of the magnetic field is performed during a cold start of the engine. In any or all of the foregoing examples, additionally or optionally, stopping the application of the magnetic field includes reducing the magnetic field at a controlled rate, where the controlled rate is based on the rate of keeping the temperature of the exhaust catalytic converter at or above the first threshold temperature. In any or all of the foregoing examples, additionally or optionally, the exhaust system component is at least partially composed of a magnetocaloric material. In any or all of the foregoing examples, additionally or optionally, the exhaust system component includes the housing of the exhaust catalytic converter. In any or all of the foregoing examples, additionally or optionally, the exhaust system component is an exhaust passage in which the exhaust catalytic converter is positioned.In any or all of the foregoing examples, the method additionally or optionally further includes applying a magnetic field to a braking system component of a vehicle equipped with an engine for a duration after a vehicle braking event; and stopping applying the magnetic field to the braking system component in response to one or more of the temperature of the braking system component reaching a third threshold temperature, reaching a calculated threshold duration of applying the magnetic field, and the start of a subsequent braking event.

[0079] As another example, a method for an engine includes: in response to the temperature of a catalyst in an exhaust system of the engine being below a first threshold temperature, heating the catalyst to the first threshold temperature by: during a first condition, applying a magnetic field to an exhaust system component of the exhaust system disposed proximate to the catalyst while maintaining the spark timing of the engine at maximum brake torque (MBT); and during a second condition, retarding the spark timing from MBT while not applying the magnetic field to the exhaust system component. In the foregoing example, in addition to or alternatively, the first condition includes that the energy and fuel economy losses of generating and applying the magnetic field to heat the catalyst to the first threshold temperature are less than the energy and fuel economy losses of retarding the spark timing to heat the catalyst to the first threshold temperature. In any or all of the foregoing examples, in addition to or alternatively, the second condition includes that the energy and fuel economy losses of generating and applying the magnetic field to heat the catalyst to the first threshold temperature are greater than or equal to the energy and fuel economy losses of retarding the spark timing to heat the catalyst to the first threshold temperature. In any or all of the foregoing examples, the method additionally or optionally further includes, during a third condition where the temperature of the catalyst is below a second threshold temperature lower than the first threshold temperature, heating the catalyst to the first threshold temperature by retarding the spark timing from MBT and applying a magnetic field to the exhaust system component.

[0080] As another example, a system for a vehicle is provided that includes: an exhaust passage of an engine, the exhaust passage including a catalyst; a magnetic field generator; and a controller having computer-readable instructions stored in a memory, the computer-readable instructions for: during a cold start of the engine, in response to the temperature of the catalyst being below a light-off temperature, activating the magnetic field generator to generate a magnetic field in a region of the catalyst. In the foregoing example, additionally or alternatively, one or more of the catalyst and the catalyst housing includes a magnetocaloric material. In any or all of the foregoing examples, the system additionally or optionally further includes a spark plug, and wherein the computer-readable instructions further include instructions for delaying a spark timing of the spark plug during a cold start in response to the temperature of the catalyst being a threshold amount below the light-off temperature and simultaneously activating the magnetic field generator to generate a magnetic field. In any or all of the foregoing examples, the system additionally or optionally further includes a brake rotor and brake pads of a braking system of the vehicle, and wherein the computer-readable instructions further include instructions for activating the magnetic field generator to generate a magnetic field in a region of one or more of the brake pads and the brake rotor after a braking event and until the temperature of one or more of the brake pads and the brake rotor drops to a lower threshold temperature or a subsequent braking event begins.

[0081] In another representation, a method includes: after a vehicle braking event, applying a magnetic field to a braking system component for a duration and then stopping the application of the magnetic field after the duration. In a first example, the duration is based on the temperature of the braking system component reaching a threshold temperature. In a second example, the duration is based on a subsequent braking event occurring, wherein when the subsequent braking event is initiated, the application of the magnetic field is stopped. In a third example, the duration is based on a previous braking event duration and timing. In any or all of the foregoing examples, the braking system component can be a brake rotor at least partially composed of a magnetocaloric material. In any or all of the foregoing examples, in addition or alternatively, the braking system component can be a brake pad at least partially composed of a magnetocaloric material.

[0082] Note that the exemplary control and estimation procedures included herein can be used with a variety of engine and / or vehicle system configurations. The control methods and procedures disclosed herein can be stored as executable instructions in a non-transitory memory and can be executed by a control system including a controller in conjunction with a variety of sensors, actuators, and other engine hardware. The specific procedures described herein can represent one or more of any number of processing strategies, such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc. Accordingly, the various acts, operations, and / or functions shown can be executed in the sequence shown, executed in parallel, or in some cases omitted. Similarly, the order of processing is not necessary to implement the features and advantages of the exemplary embodiments described herein, but is provided for ease of illustration and description. Depending on the particular strategy employed, one or more of the acts, operations, and / or functions shown can be repeated. Further, the acts, operations, and / or functions described can be graphically represented as code to be programmed into the non-transitory memory of a computer-readable storage medium for an engine control system, where the described acts are implemented by executing instructions in a system including various engine hardware components in conjunction with an electronic controller.

[0083] It should be understood that the configurations and procedures disclosed herein are exemplary in nature and these specific embodiments should not be considered limiting as many variations are possible. For example, the above techniques can be applied to V-6, V-8, V-10, I-4, I-6, V-12, opposed 4-cylinder, and other engine types. The subject matter of the present disclosure includes all novel and non-obvious combinations and sub-combinations of the various systems and configurations and other features, functions, and / or characteristics disclosed herein.

[0084] The following claims particularly point out certain combinations and sub-combinations regarded as novel and non-obvious. These claims may refer to "a" element or "a first" element or the equivalent thereof. These claims should be understood to include the combination of one or more such elements, neither requiring nor precluding two or more such elements. Other combinations and sub-combinations of the disclosed features, functions, elements, and / or characteristics can be claimed by modifying the present claims or by presenting new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope from the original claims, are also regarded as included within the subject matter of the present disclosure.

Claims

1. A method for an engine, comprising: In response to the temperature of the exhaust catalytic converter being lower than a first threshold temperature, a magnetic field is applied to an exhaust system component disposed proximate to the exhaust catalytic converter; and in response to the temperature rising to or above the first threshold temperature, application of the magnetic field is stopped, wherein applying the magnetic field to the exhaust system component is further in response to the fuel economy and energy loss of generating and applying the magnetic field to raise the temperature of the exhaust catalytic converter to the first threshold temperature being less than the fuel economy and energy loss of adjusting an alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature.

2. The method according to claim 1, wherein adjusting the alternative engine operating parameter includes delaying the spark timing of the spark plugs of one or more engine cylinders.

3. The method according to claim 2, further comprising delivering fuel to one or more engine cylinders via staged injection while delaying the spark timing.

4. The method according to claim 1, further comprising, in response to the temperature being lower than the first threshold temperature and the fuel economy and energy loss of generating and applying the magnetic field to raise the temperature of the exhaust catalytic converter to the first threshold temperature being greater than the fuel economy and energy loss of adjusting the alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature, adjusting the alternative engine operating parameter to raise the temperature of the exhaust catalytic converter to the first threshold temperature, rather than applying the magnetic field to the exhaust system component.

5. The method according to claim 1, further comprising, in response to the temperature being lower than a second threshold temperature lower than the first threshold temperature, delaying the spark at one or more engine cylinders and performing staged fuel injection at one or more engine cylinders while applying the magnetic field to the exhaust system component.

6. The method according to claim 1, wherein the first threshold temperature is the light-off temperature of the exhaust catalytic converter, and applying the magnetic field is performed during engine cold start.

7. The method according to claim 1, wherein, Stopping application of the magnetic field includes reducing the magnetic field at a controlled rate, where the controlled rate is based on the rate of keeping the temperature of the exhaust catalytic converter equal to or higher than the first threshold temperature.

8. The method according to claim 1, wherein, The exhaust system component is at least partially composed of a magnetocaloric material.

9. The method according to claim 1, wherein, The exhaust system component includes one or more of the housing of the exhaust catalytic converter and the exhaust passage in which the exhaust catalytic converter is positioned.

10. The method according to claim 1, further comprising: After a vehicle braking event, the magnetic field is applied to a braking system component of a vehicle on which the engine is mounted for a duration; and in response to one or more of the temperature of the braking system component reaching a third threshold temperature, reaching a calculated threshold duration of applying the magnetic field, and the start of a subsequent braking event, application of the magnetic field to the braking system component is stopped.

11. A system for a vehicle, comprising: An exhaust passage of the engine, the exhaust passage including a catalyst; A magnetic field generator; and A controller having computer-readable instructions stored in a memory, the computer-readable instructions for: During a cold start of the engine, in response to the temperature of the catalyst being lower than a light-off temperature, activating the magnetic field generator to generate a magnetic field in the region of the catalyst, wherein activating the magnetic field generator to generate a magnetic field in the region of the catalyst is further in response to the fuel economy and energy loss of generating and applying the magnetic field to raise the temperature of the catalyst to the light-off temperature being less than the fuel economy and energy loss of adjusting an alternative engine operating parameter to raise the temperature of the catalyst to the light-off temperature.

12. The system according to claim 11, wherein, One or more of the catalyst and the housing of the catalyst contain a magnetocaloric material.

13. The system according to claim 11, further comprising a spark plug, and wherein, The computer-readable instructions further include instructions for delaying the spark timing of a spark plug during the cold start in response to the temperature of the catalyst being a threshold amount below the light-off temperature and simultaneously activating the magnetic field generator to generate the magnetic field.

14. The system according to claim 11, further comprising brake pads and a brake rotor of the braking system of the vehicle, and wherein, The computer-readable instructions further include instructions for activating the magnetic field generator to generate a magnetic field in the region of one or more of the brake pads and the brake rotor after a braking event and until the temperature of one or more of the brake pads and the brake rotor drops to a lower threshold temperature or the start of a subsequent braking event.

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