System and method for preheating a fuel vapor storage canister

Abstract

The present application provides methods and systems for preheating a fuel vapor storage canister in an evaporative emissions system prior to vehicle start-up. In one example, a method includes learning common vehicle routes and identifying routes that indicate fuel vapor storage canister preheating, such as routes that would enable fuel vapor to be purged into an engine intake shortly after vehicle start-up. Then, in anticipation of the identified route for fuel vapor storage canister preheating, a vehicle controller may transition from a sleep mode to a wake mode prior to vehicle start-up in order to begin a fuel vapor storage canister preheating routine.

Description

Technical Field

[0001] The present description generally relates to methods and systems for preheating a fuel vapor storage canister in an evaporative emissions system of a vehicle. Background Art

[0002] The vehicle emission control system can be configured to store fuel vapor, diurnal emissions, and running loss vapor from the fuel tank refueling, and then extract / purge the stored vapor during subsequent engine operation. Specifically, the fuel vapor is stored in a fuel vapor storage canister filled with an adsorbent (e.g., activated carbon) that adsorbs and stores the vapor until they are directed to the engine intake manifold for use as fuel. The fuel vapor may include vaporized hydrocarbons with a range of carbon chain lengths. The ability of the fuel vapor storage canister to adsorb fuel vapor is enhanced at colder temperatures, and the ability of the fuel vapor storage canister to desorb fuel vapor is enhanced at hotter temperatures. When fresh air flows through the fuel vapor storage canister, lower molecular weight hydrocarbons (also referred to herein as "light fractions") (such as one carbon methane to four carbon butane) can be easily desorbed during purging. However, higher molecular weight hydrocarbons (also referred to herein as "heavy fractions") (such as seven carbon heptanes and above) resist movement during purging without heat to encourage them to desorb from the adsorbent. As a result, if heat is not applied, the fuel vapor storage canister cleaning may be incomplete during purging due to the trapped heavy fractions. Incomplete fuel vapor storage canister cleaning may result in more blowdown emissions. For example, when the vehicle is bathed in sunlight, the fuel vapor storage canister may heat up enough to cause the heavy fractions to desorb and escape into the atmosphere.

[0003] Additionally, in a stop / start vehicle where the engine is shut off while the vehicle remains on, such as when the vehicle is stopped, frequent engine shutoffs may reduce opportunities to purge the fuel vapor storage canister. Reduced opportunities to purge may result in high vapor loads on the fuel vapor storage canister, thereby increasing vented emissions. Therefore, it may be beneficial to quickly purge both the light and heavy fractions as quickly as possible to ensure effective cleaning of the fuel vapor storage canister.

[0004] Other attempts to reduce vented emissions by effectively purging hydrocarbon heavy fractions include using a heated fuel vapor storage canister. Peters et al. show an example method in US 20150090232 A1. Therein, a method for adjusting a heater of a fuel vapor storage canister based on a purge flow rate leaving the fuel vapor storage canister and a concentration of hydrocarbons released from the fuel vapor storage canister is disclosed. In addition, to offset the relatively low temperatures reached by the fuel vapor storage canister during engine shutdown in a hybrid vehicle (e.g., when the engine is not rotating and not burning air and fuel), where heating the fuel vapor storage canister during purging may render the purging ineffective, the heater of the fuel vapor storage canister may be maintained at a temperature below the temperature desired for purging but above ambient temperature.

[0005] However, the inventors have recognized that maintaining the fuel vapor storage canister heater on, even at a low level, consumes energy. As an example, it is unknown when or if the engine will be turned back on for purging during a drive cycle. Therefore, the fuel vapor storage canister may be heated unnecessarily, which may waste energy. Summary of the invention

[0006] In one example, the above problem can be addressed by an evaporative emissions method that includes: preheating a fuel vapor storage canister in an evaporative emissions system of a vehicle to a desired temperature within a determined duration before starting a drive cycle while the vehicle remains off; and purging vapor stored in the fuel vapor storage canister into an intake of the vehicle engine after the drive cycle begins. In this way, cleaning of the fuel vapor storage canister can be accelerated.

[0007] As an example, a drive cycle may be a learned drive cycle that enables purging to occur within a threshold duration after the start of the drive cycle. For example, purging may occur if the engine is operating above idle and the vacuum in the intake is above a threshold vacuum. Further, an evaporative emissions system test may be performed prior to the start of the drive cycle and while the fuel vapor storage canister is preheated to determine if the evaporative emissions system is degraded. For example, if the pressure of the evaporative emissions system does not reach a threshold pressure, it may be determined that the evaporative emissions system is degraded. Energy may be saved by heating the fuel vapor storage canister only when conditions are expected to be met to purge the fuel vapor storage canister. Further, by performing the evaporative emissions system test while the fuel vapor storage canister is preheated, the energy expended in preheating the fuel vapor storage canister may be utilized even if purging does not occur.

[0008] 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. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is solely defined by the claims attached to the detailed description. Furthermore, the claimed subject matter is not limited to embodiments that address any disadvantages noted above or in any part of this disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 An example vehicle propulsion system is schematically illustrated.

[0010] Figure 2 A schematic diagram showing a fuel system and an evaporative emissions system coupled to an engine system.

[0011] Figure 3 is a flow chart of an example method for learning a travel route during a drive cycle of a vehicle.

[0012] Figure 4 is a flow chart of an example method for preheating a fuel vapor storage canister in an evaporative emissions system of a vehicle when the vehicle is turned off based on a predicted drive cycle.

[0013] Figure 5 An example timeline is shown for preheating a fuel vapor storage canister in anticipation of a drive cycle in which purging may occur. DETAILED DESCRIPTION

[0014] The following description relates to systems and methods for purging a fuel vapor storage canister in a vehicle evaporative emissions system, wherein the fuel vapor storage canister is thoroughly purged of both light and heavy hydrocarbon fractions by preheating the fuel vapor storage canister prior to vehicle start-up. These systems and methods may be applied to stop / start vehicles or hybrid vehicles such as Figure 1 ), but it should be understood that the systems and methods described herein are not limited to such vehicle systems. For example, these systems and methods can be applied to any vehicle that includes an evaporative emissions system coupled to a fuel system and an engine (such as a Figure 2 When the vehicle is turned off, the fuel vapor storage canister may be preheated in anticipation of an upcoming driving route where a purging event may occur. Figure 3 The example method of knows such a driving route. Figure 4 An example method for diagnosing the presence of degradation in an evaporative emissions system while preheating a fuel vapor storage canister and then thoroughly purging both light and heavy hydrocarbon fractions is depicted in FIG. Figure 5 An example timeline for preheating a fuel vapor storage canister based on a predicted travel route to expedite a thorough fuel vapor storage canister cleaning is shown in FIG.

[0015] Figure 1 An example vehicle system 100 is shown. The vehicle system 100 includes a fuel combustion engine 110 and a motor 120. As a non-limiting example, the engine 110 includes an internal combustion engine and the motor 120 includes an electric motor. The motor 120 can be configured to utilize or consume a different energy source than the engine 110. For example, the engine 110 can consume a liquid fuel (e.g., gasoline) to produce an engine output, while the motor 120 can consume electrical energy to produce a motor output. Therefore, a vehicle having a propulsion system 100 can be referred to as a hybrid electric vehicle (HEV).

[0016] The vehicle system 100 can utilize a variety of different operating modes depending on the operating conditions encountered by the vehicle propulsion system. Some of these modes can enable the engine 110 to maintain a shut-down state (e.g., set to a deactivated state) that interrupts fuel combustion at the engine. For example, under selected operating conditions, the motor 120 can propel the vehicle via the drive wheels 130 as shown by arrow 122 when the engine 110 is deactivated.

[0017] During other operating conditions, the engine 110 can be set to a deactivated state (as described above), while the motor 120 can be operated to charge the energy storage device 150. For example, the motor 120 can receive wheel torque from the drive wheel 130 (as shown by arrow 122), and can convert the kinetic energy of the vehicle into electrical energy to be stored at the energy storage device 150 (as shown by arrow 124). This operation can be referred to as regenerative braking of the vehicle. Therefore, in some examples, the motor 120 can be used as a generator. However, in other examples, the generator 160 can alternatively receive wheel torque from the drive wheel 130 and can convert the kinetic energy of the vehicle into electrical energy to be stored at the energy storage device 150 (as shown by arrow 162). As an additional example, the motor 120 can use the energy stored at the energy storage device 150 to start the engine 110 in a starting operation (as shown by arrow 186).

[0018] During other operating conditions, the engine 110 can be operated by burning fuel received from the fuel system 140 (as shown by arrow 142). For example, the engine 110 can be operated to propel the vehicle via the drive wheels 130 (as shown by arrow 112) while the motor 120 is deactivated. During other operating conditions, both the engine 110 and the motor 120 can be operated to propel the vehicle via the drive wheels 130 (as shown by arrow 112 and arrow 122), respectively. A configuration in which both the engine and the motor can selectively propel the vehicle can be referred to as a parallel vehicle propulsion system. Note that in some examples, the motor 120 can propel the vehicle via a first set of drive wheels, and the engine 110 can propel the vehicle via a second set of drive wheels.

[0019] In other examples, the vehicle system 100 can be configured as a series vehicle propulsion system, whereby the engine does not directly propel the drive wheels. Instead, the engine 110 can be operated to power the motor 120, which can then propel the vehicle via the drive wheels 130 (as shown by arrow 122). For example, during a selected operating condition, the engine 110 can drive the generator 160 (as shown by arrow 116), which can then supply electrical energy to one or more of the motor 120 (as shown by arrow 114) or the energy storage device 150 (as shown by arrow 162). As another example, the engine 110 can be operated to drive the motor 120, which can then be used as a generator to convert the engine output into electrical energy. For example, electrical energy can be stored at the energy storage device 150 for later use by the motor.

[0020] The fuel system 140 may include one or more fuel storage tanks 144 for storing fuel on the vehicle. For example, the fuel tank 144 may store one or more liquid fuels, including (but not limited to) gasoline, diesel, and alcohol fuels. In some examples, the fuel may be stored on the vehicle as a blend of two or more different fuels. For example, the fuel tank 144 may be configured to store a blend of gasoline and ethanol (such as E10, E85, etc.) or a blend of gasoline and methanol (such as M10, M85, etc.), whereby these fuels or fuel blends may be delivered to the engine 110 as shown in arrow 142. Other suitable fuels or fuel blends may also be supplied to the engine 110, and the fuel or fuel blends may be burned at the engine 110 to generate an engine output (e.g., torque). The engine output may be used to propel the vehicle (as shown in arrow 112) or to recharge the energy storage device 150 via the motor 120 or the generator 160.

[0021] In some examples, energy storage device 150 may be configured to store electrical energy that may be supplied to other electrical loads (other than the motor) resident on the vehicle, including a cabin heating and air conditioning system, an engine starting system, a headlight system, a cabin audio and video system, etc. As non-limiting examples, energy storage device 150 may include one or more batteries and / or capacitors.

[0022] Control system 190 may communicate with one or more of engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160. Control system 190 may receive sensory feedback information from one or more of engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160. Further, control system 190 may send control signals to one or more of engine 110, motor 120, fuel system 140, energy storage device 150, and generator 160 in response to the sensory feedback.

[0023] The control system 190 may receive an indication of an operator-requested vehicle propulsion system output from the vehicle operator 102. For example, the control system 190 may receive sensory feedback regarding the position of a pedal 192 from a pedal position sensor 194. The pedal 192 may schematically refer to a brake pedal and / or an accelerator pedal that may be depressed by the vehicle operator 102. Additionally, in some examples, the control system 190 may communicate with a remote engine start receiver 195 (or transceiver) that receives a wireless signal 106 from a key fob 104 having a remote start button 105. In other examples (not shown), a remote engine start may be initiated via a cellular phone or smartphone-based system, where the user's phone sends data to a server and the server communicates with the vehicle to start the engine.

[0024] The energy storage device 150 may periodically receive electrical energy (as indicated by arrow 184) from a power source 180 residing outside the vehicle (e.g., an external fixed power grid that is not part of the vehicle). As a non-limiting example, the vehicle system 100 may be configured as a plug-in HEV, whereby electrical energy may be supplied to the energy storage device 150 from the power source 180 via a power transmission cable 182. During a recharging operation of the energy storage device 150 from the power source 180, the power transmission cable 182 may electrically couple the energy storage device 150 and the power source 180. When operating the vehicle propulsion system to propel the vehicle, the power transmission cable 182 may be disconnected between the power source 180 and the energy storage device 150. The control system 190 may identify and / or control the amount of electrical energy stored at the energy storage device, which may be referred to as the state of charge (SOC).

[0025] In other examples, power transmission cable 182 may be omitted, where power may be received wirelessly at energy storage device 150 from power source 180. For example, energy storage device 150 may receive power from power source 180 via one or more of electromagnetic induction, radio waves, and electromagnetic resonance. Thus, it should be appreciated that energy storage device 150 may be recharged using any suitable method from a power source that does not include a portion of the vehicle. In this manner, motor 120 may propel the vehicle by utilizing an energy source other than the fuel utilized by engine 110.

[0026] In other examples, the vehicle system 100 may include one or more solar cells 108 operable to convert incident solar radiation into electrical energy. The solar cell 108 is electrically coupled to the solar battery 30 via a charge controller 32. The solar cell 108 and the charge controller 32 are operable to supply current for charging the solar battery 30. In this example, the solar battery 30 is housed within and electrically coupled to the energy storage device 150, but in other configurations, the solar battery 30 may be electrically coupled to the energy storage device 150 while being housed separately. In other configurations, the solar battery 30 may be both physically and electrically isolated from the energy storage device 150. Thus, the solar battery 30 may be configured to provide charge or receive charge from the energy storage device 150 based on engine operating conditions, charge state, and battery (or) requirements. The solar battery 30 may be configured to independently supply charge directly to vehicle actuators and devices, as will be discussed herein with respect to Figure 4 Further described. In some examples, charge controller 32 can be used to directly power vehicle actuators and devices without first storing charge in solar battery 30 .

[0027] The solar cell 108 may be mounted on any convenient exterior surface of the vehicle, such as the roof, hood, trunk, etc. However, the solar cell 108 may additionally or alternatively be mounted on the interior of the vehicle, such as on the dashboard or other passenger compartment surface near a window or interior light bulb. Typically, a solar cell is operable to convert solar radiation incident thereon into electrical energy. In some embodiments, the solar cell 108 may include a series of photovoltaic cells formed from an amorphous semiconductor material, such as silicon. Additionally, the individual photovoltaic cells may be interconnected to provide a constant flow of electrical energy to a common output cable 188, which electrically couples the solar cell 108 to the charge controller 32 and the solar battery 30. In this manner, the solar cell 108 may generate electrical energy that is utilized to propel the vehicle or to power one or more additional vehicle actuators and devices.

[0028] Fuel system 140 may periodically receive fuel from a fuel source residing outside the vehicle. As a non-limiting example, vehicle system 100 may be refueled by receiving fuel via fuel dispensing device 170 (as indicated by arrow 172). In some examples, fuel tank 144 may be configured to store fuel received from fuel dispensing device 170 until the fuel is supplied to engine 110 for combustion. In some examples, control system 190 may receive an indication of the level of fuel stored in fuel tank 144 via a fuel level sensor. The level of fuel stored in fuel tank 144 (e.g., as identified by the fuel level sensor) may be communicated to a vehicle operator, for example, via a fuel gauge or indication in a vehicle instrument panel (e.g., message center) 196.

[0029] The vehicle system 100 may also include an ambient temperature / humidity sensor 198 and a roll stability control sensor, such as (one or more) lateral and / or longitudinal and / or yaw rate sensor 199. The vehicle dashboard 196 may include (one or more) indicator lights and / or a text-based display in which messages are displayed to the operator. The vehicle dashboard 196 may also include various input devices for receiving operator input, such as buttons, touch screens, voice input / recognition, etc. For example, the vehicle dashboard 196 may include a refueling button 197 that can be manually actuated or pressed by the vehicle operator to start refueling. For example, as described in more detail below, in response to the vehicle operator actuating the refueling button 197, a fuel tank in the vehicle (e.g., fuel tank 144) may be depressurized so that refueling can be performed.

[0030] As is known in the art, the control system 190 can be communicatively coupled to other vehicles or infrastructure using appropriate communication technologies. For example, the control system 190 can be coupled to other vehicles or infrastructure via a wireless network 131, which may include Wi-Fi, Bluetooth, some type of cellular service, wireless data transmission protocol, etc. The control system 190 can broadcast (and receive) information about vehicle data, vehicle diagnostics, traffic conditions, vehicle location information, vehicle operating procedures, etc. via vehicle-to-vehicle (V2V), vehicle-to-infrastructure-to-vehicle (V2I2V) and / or vehicle-to-infrastructure (V2I or V2X) technologies. The information exchanged between vehicles can be transmitted directly between vehicles, or can be multi-hop. In some examples, longer-range communications (e.g., WiMax) can be used instead of V2V or V2I2V, or longer-range communications can be used in combination with V2V or V2I2V to extend the coverage area by several miles. In other examples, as is known in the art, the vehicle control system 190 can be communicatively coupled to other vehicles or infrastructure via a wireless network 131 and the Internet (e.g., cloud).

[0031] The vehicle system 100 may also include an onboard navigation system 132 (e.g., a global positioning system) with which the vehicle operator may interact. The navigation system 132 may include one or more positioning sensors to help estimate vehicle speed, vehicle altitude, vehicle position / location, etc. This information may be additionally used to infer engine operating parameters, such as local atmospheric pressure. As described above, the control system 190 may be further configured to receive information via the Internet or other communication networks. Information received from the GPS may be cross-referenced with information obtained via the Internet to determine local weather conditions, local vehicle regulations, etc.

[0032] Figure 2 206. It should be understood that the vehicle system 206 may include Figure 1 The vehicle system 206 may be similar to the vehicle system 100 depicted in FIG. 200 . The vehicle system 206 may be powered by an engine system 208 and / or an onboard energy storage device such as Figure 1 The energy storage device 150 shown in FIG. 1 is used to obtain propulsion power. An energy conversion device (such as a generator (e.g., Figure 1 The generator 160)) can be operated to absorb energy from vehicle movement and / or engine operation and convert the absorbed energy into an energy form suitable for storage by the energy storage device.

[0033] The engine system 208 may include an engine 210 having a plurality of cylinders 230. The engine 210 may be, for example, Figure 1 1. The engine 110 shown in FIG. The engine 210 may include an engine intake system 223 and an engine exhaust system 225. The engine intake system 223 may include an intake throttle 262 fluidly coupled to an engine intake manifold 244 via an intake passage 242. Air may be directed to the intake throttle 262 after passing through an air filter 252 coupled to the intake passage 242 upstream of the intake throttle 262. The engine exhaust system 225 includes an exhaust manifold 248 leading to an exhaust passage 235, which directs exhaust gas to the atmosphere. The engine exhaust system 225 may include one or more emission control devices 270 mounted in a close-coupled position. The one or more emission control devices may include a three-way catalyst, a lean NOx trap, a particulate filter (e.g., a diesel particulate filter or a gasoline particulate filter), an oxidation catalyst, etc. It should be understood that other components (such as various valves and sensors) may be included in the engine as further described herein. In some embodiments, where the engine system 208 is a boosted engine system, the engine system may further include a boosting device, such as a turbocharger (not shown).

[0034] The engine system 208 is coupled to a fuel system 218 and an evaporative emissions system 219. The fuel system 218 includes a fuel tank 220 coupled to a fuel pump 234 that supplies fuel to the engine 210 that propels the vehicle system 206. The evaporative emissions system 219 includes a fuel vapor storage canister 222. During a fuel tank refueling event, fuel may be pumped into the vehicle from an external source through a refueling port 284. The fuel tank 220 may hold a variety of fuel blends, including fuels having a range of alcohol concentrations, such as various gasoline-ethanol blends (including E10, E85, gasoline, etc.), and combinations thereof. A fuel level sensor 282 located in the fuel tank 220 may provide a control system 290 (which may be, for example, a fuel level sensor 282 that is configured to detect the level of the fuel level) to be present. Figure 1 Controller 12 of control system 190 of the invention provides an indication of the fuel level ("fuel level input"). As depicted, fuel level sensor 282 may include a float connected to a variable resistor. Alternatively, other types of fuel level sensors may be used.

[0035] Fuel pump 234 is configured to deliver pressurized fuel to fuel injectors (such as exemplary fuel injector 266) of engine 210. Although only a single fuel injector 266 is shown, additional fuel injectors may be provided for each cylinder. It should be appreciated that fuel system 218 may be a returnless fuel system, a return fuel system, or various other types of fuel systems. Vapors generated in fuel tank 220 may be directed to fuel vapor storage canister 222 via conduit 231 for storage before being purged into engine intake system 223.

[0036] The fuel vapor storage canister 222 is filled with a suitable adsorbent 280 for temporarily capturing fuel vapors (including vaporized hydrocarbons), diurnal vapors, and operating loss vapors generated during fuel tank refueling operations. In one example, the adsorbent 280 is activated carbon (e.g., carbon). Although a single fuel vapor storage canister 222 is shown, it should be understood that the fuel system 218 and the evaporative emissions system 219 may include any number of fuel vapor storage canisters. When the purge conditions are met, such as when the fuel vapor storage canister is saturated, the vapors stored in the fuel vapor storage canister 222 can be purged to the engine intake system 223 by opening the canister purge valve (CPV) 212, which can be a normally closed valve. In one example, the canister purge valve 212 can be a solenoid valve, wherein the opening or closing of the valve is performed via actuation of a canister purge solenoid.

[0037] The fuel vapor storage canister 222 may include a buffer 222a (or a buffer region), each of which includes an adsorbent. For example, the buffer 222a is shown as being filled with an adsorbent 280a. As shown, the volume of the buffer 222a may be less than the volume of the fuel vapor storage canister 222 (e.g., a portion thereof). The adsorbent 280a in the buffer 222a may be the same as or different from the adsorbent 280 in the fuel vapor storage canister (e.g., both may include charcoal). The buffer 222a may be positioned within the fuel vapor storage canister 222 such that during fuel vapor storage canister loading, the fuel tank vapor is first adsorbed within the buffer, and then when the buffer is saturated, further fuel tank vapor is adsorbed in the fuel vapor storage canister. In contrast, during fuel vapor storage canister purging, the fuel vapor is first desorbed from the fuel vapor storage canister (e.g., to a threshold amount) before desorbing from the buffer. In other words, the loading and unloading of the buffer is not linearly related to the loading and unloading of the fuel vapor storage canister. Thus, the effect of the fuel vapor storage canister buffer is to dampen any fuel vapor spikes flowing from the fuel tank to the fuel vapor storage canister, thereby reducing the likelihood of any fuel vapor spikes entering the engine.

[0038] Fuel vapor storage canister 222 includes a vent 227 for directing gas from fuel vapor storage canister 222 to the atmosphere when storing fuel vapor from fuel tank 220. Vent 227 may also allow fresh air to be drawn into fuel vapor storage canister 222 when stored fuel vapor is purged into engine intake system 223 via purge line 228 and canister purge valve 212. Although this example shows vent 227 communicating with fresh, unheated air, various modifications may also be used. Vent 227 may include a canister vent valve (CVV) 214 to regulate the flow of air and vapor between fuel vapor storage canister 222 and the atmosphere. When a vent valve is included, the vent valve may be a normally open valve so that air stripped of fuel vapor after passing through the fuel vapor storage canister can be pushed out to the atmosphere (e.g., during refueling when the engine is off). Likewise, during a purge operation (e.g., during fuel vapor storage canister regeneration and while the engine is running), the fuel vapor storage canister vent valve may be opened to allow fresh air flow to strip fuel vapor stored in the fuel vapor storage canister. In one example, canister vent valve 214 may be a solenoid valve, where opening or closing of the solenoid valve is performed via actuation of a canister vent solenoid. In particular, the canister vent valve may be in an open position that is closed when the canister vent solenoid is actuated.

[0039] The evaporative emission system 219 may further include a purge fuel vapor storage canister 211. Hydrocarbons desorbed from a fuel vapor storage canister 222 (hereinafter also referred to as a "primary fuel vapor storage canister") may be adsorbed within the purge fuel vapor storage canister. The purge fuel vapor storage canister 211 may include an adsorbent material different from that included in the primary fuel vapor storage canister 222. Alternatively, the adsorbent material in the purge fuel vapor storage canister 211 may be the same as that included in the primary fuel vapor storage canister 222.

[0040] A hydrocarbon (HC) sensor 213 may be present in the evaporative emission system 219 to indicate the concentration of hydrocarbons in the exhaust port 227. As shown, the hydrocarbon sensor 213 is located between the main fuel vapor storage canister 222 and the blowdown fuel vapor storage canister 211. The probe (e.g., sensing element) of the hydrocarbon sensor 213 is exposed to the fluid flow in the exhaust port 227 and senses the hydrocarbon concentration of the fluid flow. In one example, the engine control system 290 may use the hydrocarbon sensor 213 to determine the breakthrough of hydrocarbon vapors from the main fuel vapor storage canister 222.

[0041] One or more temperature sensors 215 may be coupled to the fuel vapor storage canister 222 and / or within the fuel vapor storage canister 222. When fuel vapor is adsorbed by the adsorbent in the fuel vapor storage canister, heat (adsorption heat) is generated. Similarly, when fuel vapor is desorbed by the adsorbent in the fuel vapor storage canister, heat is consumed. In this way, the adsorption and desorption of fuel vapor by the fuel vapor storage canister may be monitored and estimated based on the temperature change within the fuel vapor storage canister. Further, one or more canister heating elements 216 may be coupled to the fuel vapor storage canister 222 and / or within the fuel vapor storage canister 222. The canister heating element 216 may be used, for example, to selectively heat the fuel vapor storage canister (and the adsorbent contained therein) to increase the desorption of fuel vapor before performing a purge operation. As described above, heating the fuel vapor storage canister may be particularly beneficial for purging hydrocarbon heavy fractions. The canister heating element 216 may include an electrical heating element, such as an electrically conductive metal, ceramic, or carbon element that can be electrically heated. In some embodiments, the tank heating element 216 may include a microwave energy source or may include a fuel vapor storage canister jacket coupled to a hot air source or a hot water source. The tank heating element 216 may be coupled to one or more heat exchangers that may facilitate the transfer of heat (e.g., from hot exhaust) to the fuel vapor storage canister 222. The tank heating element 216 may be configured to heat the air within the fuel vapor storage canister 222 and / or directly heat the adsorbent located within the fuel vapor storage canister 222. In some embodiments, the tank heating element 216 may be included in a heater chamber coupled to the interior or exterior of the fuel vapor storage canister 222. In some embodiments, the fuel vapor storage canister 222 may be coupled to one or more cooling circuits and / or cooling fans. In this way, the fuel vapor storage canister 222 may be selectively cooled to increase the adsorption of fuel vapor (e.g., before a refueling event). In some examples, the tank heating element 216 may include one or more Peltier elements that may be configured to selectively heat or cool the fuel vapor storage canister 222.

[0042] The vehicle system 206 may have reduced engine operating time due to the vehicle being powered by the engine system 208 during some conditions and powered by the energy storage device during other conditions (such as when the vehicle system 206 is included in a hybrid vehicle), or due to the engine being off when the vehicle is on and stationary (such as when the vehicle system 206 is included in a stop / start vehicle). While reduced engine operating time reduces total carbon emissions from the vehicle, they may also result in inadequate purging of fuel vapor from the evaporative emissions system 219. To at least partially address this issue, a fuel tank isolation valve (FTIV) 236 may optionally be included in conduit 231 such that the fuel tank 220 is coupled to the fuel vapor storage canister 222 via the valve. During normal engine operation, the FTIV 236 may remain closed to limit the amount of diurnal vapor or "running loss" vapor directed from the fuel tank 220 to the fuel vapor storage canister 222. During refueling operations and selected purging conditions, FTIV 236 may be temporarily opened, for example, for a duration, to direct fuel vapors from fuel tank 220 to fuel vapor storage canister 222. By opening the valve during purging conditions or when the fuel tank pressure is above a threshold (e.g., above the mechanical pressure limit of the fuel tank), refueling vapors may be released into the fuel vapor storage canister and the fuel tank pressure may be maintained below the pressure limit. While the depicted example shows isolation valve 236 positioned along conduit 231, in alternative embodiments, the isolation valve may be mounted on fuel tank 220.

[0043] One or more pressure sensors may be coupled to fuel system 218 and evaporative emissions system 219 to provide estimates of fuel system and evaporative emissions system pressures, respectively. Figure 2 In the example shown, a first pressure sensor 217 is coupled directly to the fuel tank 220, and a second pressure sensor 238 is coupled to the conduit 231 between the FTIV 236 and the fuel vapor storage canister 222. For example, the first pressure sensor 217 may be a fuel tank pressure transducer (FTPT) coupled to the fuel tank 220 for measuring the pressure of the fuel system 218, and the second pressure sensor 238 may measure the pressure of the evaporative emissions system 219. In alternative embodiments, the first pressure sensor 217 may be coupled between the fuel tank 220 and the fuel vapor storage canister 222, specifically between the fuel tank and the FTIV 236. In other embodiments, a single pressure sensor may be included for measuring both the fuel system pressure and the evaporative system pressure, such as when the FTIV 236 is open or omitted. In some examples, the engine control system 290 may infer and indicate undesirable evaporative emissions (e.g., undesirable hydrocarbon emissions) based on changes in the evaporative emissions system pressure during emissions testing, as described below with respect to Figure 4 Further description.

[0044] One or more temperature sensors 221 may also be coupled to fuel system 218 for providing an estimate of fuel system temperature. In one example, the fuel system temperature is a fuel tank temperature, where temperature sensor 221 is a fuel tank temperature sensor coupled to fuel tank 220. While the depicted example shows temperature sensor 221 coupled directly to fuel tank 220, in alternative embodiments, the temperature sensor may be coupled between the fuel tank and fuel vapor storage canister 222.

[0045] Fuel vapors released from the fuel vapor storage canister 222, such as during a purge operation, can be directed into the engine intake manifold 244 via a purge line 228. The flow of vapors along the purge line 228 can be regulated by a canister purge valve 212, which is coupled between the fuel vapor storage canister and the engine intake. The amount and rate of vapors released by the fuel vapor storage canister purge valve can be determined by the duty cycle of an associated canister purge valve solenoid (not shown). Thus, the duty cycle of the canister purge valve solenoid can be determined by the controller 12 in response to engine operating conditions, including, for example, engine speed-load conditions, air-fuel ratio, fuel vapor storage canister load, etc. By commanding the canister purge valve to close, the controller can isolate the fuel vapor recovery system from the engine intake system. An optional canister check valve (not shown) can be included in the purge line 228 to prevent the intake manifold pressure from causing gas to flow in the opposite direction of the purge flow. Thus, the check valve may be beneficial if the canister purge valve control is not precisely timed or the canister purge valve itself can be forced open by high intake manifold pressure. An estimate of manifold absolute pressure (MAP) or manifold vacuum (ManVac) may be obtained by controller 12 from MAP sensor 240 coupled to intake manifold 244. Alternatively, MAP may be inferred from alternative engine operating conditions, such as mass air flow (MAF) measured by a MAF sensor (not shown) coupled to the intake manifold.

[0046] By selectively adjusting the various valves and solenoids, the fuel system 218 and the evaporative emissions system 219 may be operated by the controller 12 in a variety of modes. For example, the fuel system and the evaporative emissions system may be operated in a refueling mode (e.g., when the vehicle operator requests refueling of the fuel tank), wherein the controller 12 may open the FTIV 236 and the canister vent valve 214 while maintaining the canister purge valve 212 closed to depressurize the fuel tank before enabling fuel to be added to the fuel tank. Thus, the FTIV 236 may remain open during the refueling operation to allow refueling vapors to be stored in the fuel vapor storage canister. After refueling is complete, the isolation valve may be closed. By maintaining the canister purge valve 212 closed, the refueling vapors are directed into the fuel vapor storage canister 222 while preventing the fuel vapors from flowing into the intake manifold. As another example, the fuel system and evaporative emissions system may be operated in a fuel vapor storage canister purge mode (e.g., after the emission control device light-off temperature has been reached and with the engine running), where controller 12 may open canister purge valve 212 and canister vent valve 214 while closing FTIV 236. Vacuum generated by the engine's intake manifold may be used to draw fresh air through exhaust port 227 and through fuel vapor storage canister 222 to purge stored fuel vapor into intake manifold 244. In this mode, fuel vapor purged from the fuel vapor storage canister is combusted in the engine. Purging may continue until the amount of fuel vapor stored in the fuel vapor storage canister is below a threshold.

[0047] During the purging, the learned vapor amount / concentration may be used to determine the amount of fuel vapor stored in the fuel vapor storage canister, and then during a later portion of the purging operation (when the fuel vapor storage canister is sufficiently purged or empty), the learned vapor amount / concentration may be used to estimate the loading state of the fuel vapor storage canister. For example, one or more oxygen sensors (not shown) may be coupled to fuel vapor storage canister 222 (e.g., downstream of the fuel vapor storage canister) or positioned in the engine intake and / or the engine exhaust to provide an estimate of the fuel vapor storage canister loading (i.e., the amount of fuel vapor stored in the fuel vapor storage canister). Based on the fuel vapor storage canister loading and further based on engine operating conditions (such as engine speed-load conditions), a purge flow rate may be determined.

[0048] The vehicle system 206 may further include a control system 290. The control system 290 is shown receiving information from a plurality of sensors 16 (various examples of which are described herein) and sending control signals to a plurality of actuators 81 (various examples of which are described herein). As one example, the sensors 16 may include an exhaust gas sensor 226 located upstream of the emission control device 270, a temperature sensor 232 coupled to the exhaust passage 235, a MAP sensor 240, an FTPT 217, a second pressure sensor 238, a hydrocarbon sensor 213, a temperature sensor 221, and a pressure sensor 229 located downstream of the emission control device 270. Other sensors (such as additional pressure sensors, temperature sensors, air-fuel ratio sensors, and composition sensors) may be coupled to various locations in the vehicle system 206. As another example, the actuators 81 may include a fuel injector 266, a FTIV 236, a purge valve 212, an exhaust valve 214, a fuel pump 234, and a throttle 262.

[0049] As referenced above Figure 1 As described, the control system 290 may further receive information about the vehicle's location from the onboard GPS. The information received from the GPS may include vehicle speed, vehicle altitude, vehicle location, etc. This information may be used to infer engine operating parameters, such as local atmospheric pressure. The control system 290 may further be configured to receive information via the Internet or other communication networks. The information received from the GPS may be cross-referenced with information obtained via the Internet to determine local weather conditions, local vehicle regulations, etc. The control system 290 may use the Internet to obtain updated software modules, which may be stored in non-transitory memory.

[0050] The controller 12 of the control system 290 may be configured as a conventional microcomputer, including a microprocessor unit, input / output ports, read-only memory, random access memory, non-failure memory, a controller area network (CAN) bus, etc. The controller 12 may be configured as a powertrain control module (PCM). The controller may receive input data from various sensors, process the input data, and trigger actuators based on instructions or codes programmed therein corresponding to one or more programs in response to the processed input data. Figure 3 and Figure 4 Describes a sample control program.

[0051] In some examples, the controller can be placed in a reduced power mode or sleep mode in which the controller maintains only basic functionality and operates with lower battery consumption than a corresponding wake-up mode. For example, the controller can be placed in sleep mode after a vehicle shutdown event (e.g., a human driver removes a key from the vehicle and / or leaves the vicinity of the vehicle using a key fob, at which time the engine may stop rotating and the electric propulsion device (if present) may be deactivated) to perform diagnostic routines for a duration after the vehicle shutdown event. The controller can have a wake-up input that allows the controller to return to the wake-up mode based on input received from one or more sensors. For example, opening a vehicle door can trigger a return to the wake-up mode. In other examples, particularly with respect to Figure 4 In the fuel vapor storage canister preheating method depicted in , it may be necessary to wake up the controller in order to implement one or more methods. In such an example, the controller may set a timer after a vehicle shutdown event and before entering a sleep mode so that the controller can be woken up before the vehicle is turned on to preheat the fuel vapor storage canister, as further described below. For example, when the timer expires, the circuit may wake up the controller to begin the fuel vapor storage canister preheating procedure.

[0052] The controller 12 may also be configured to intermittently perform an evaporative emissions system diagnostic routine to determine the presence or absence of undesirable evaporative emissions in the evaporative emissions system and / or the fuel system. Thus, various evaporative emissions diagnostic tests may be performed when the engine is off (engine off evaporative emissions test) or when the engine is running (engine on evaporative emissions test). As an example, when the engine is off, the evaporative emissions system may be sealed and the pressure monitored. If the evaporative emissions system is heated due to desorption of fuel vapors desorbed from the fuel vapor storage canister, the pressure may increase further. If the pressure rise meets or exceeds a predetermined threshold, it may indicate that the evaporative emissions system is free of undesirable evaporative emissions (e.g., there is no evaporative emissions system degradation). Alternatively, if the pressure does not reach the threshold, there may be undesirable evaporative emissions (e.g., there may be evaporative emissions system degradation). Thus, an emissions test may be performed with a preheating of the fuel vapor storage canister for accelerated canister cleaning.

[0053] Now go to Figure 3, which shows a high-level example method 300 for learning common driving routes traveled by a vehicle. More specifically, method 300 may be utilized to learn common driving routes in order to identify routes for fuel vapor storage canister preheating, such as routes where fuel vapor storage canister purging will occur. For example, routes where the engine is active for at least a threshold duration may enable fuel vapor storage canister purging, while routes where the engine is frequently deactivated may not enable fuel vapor storage canister purging. The timing and duration of learned / predicted engine deactivation events corresponding to a particular driving route may be stored in a lookup table(s) stored at a vehicle controller. Such information may be utilized in order to schedule fuel vapor storage canister preheating prior to vehicle start-up, as will be discussed in detail below.

[0054] Reference will be made to the description herein and in Figure 1 and Figure 2 The method 300 is described with reference to the system shown in FIG. 1 , but it should be understood that similar methods may be applied to other systems without departing from the scope of the present disclosure. Figure 2 The controller 12) is based on instructions stored in the memory of the controller and in conjunction with the vehicle system from the sensor (such as the above reference Figure 1 and Figure 2 The controller may actuate the vehicle system actuators according to the methods described below, such as those described above with reference to Figure 1 and Figure 2 Actuator described.

[0055] Method 300 begins at 302 and includes determining whether a key-on event is indicated. A key-on event may include using an ignition key to start the engine in an engine-on mode (in which the engine (such as Figure 1 Combustion occurs in the engine 110 and the torque generated is used to propel the vehicle) or in an electric-only operating mode (in which the engine is turned off and an electric motor (such as Figure 1 The vehicle may be started at 302 (the engine 120 is powered to propel the vehicle). In other examples, the key-on event may include pressing an ignition button to activate a vehicle system. Other examples may include a key fob (or other remote device, including a smartphone, tablet, etc.) activating the vehicle in an engine-on mode or an electric-only operating mode. If a key-on event is not indicated at 302, method 300 proceeds to 304 and includes maintaining current vehicle operating parameters. For example, an engine, electric motor, etc. may be maintained in its current operating mode. Method 300 may then end.

[0056] Returning to 302 , in response to indicating a key-on event, method 300 proceeds to 306 and includes accessing vehicle location, vehicle speed, driver information, day of week (DOW), time of day (TOD), etc. The driver's identity may be input by the driver or inferred based on driving habits, seat position, cabin climate control preferences, voice activation commands, etc. The vehicle location may be accessed via an onboard navigation system (e.g., via GPS) or by other means (such as via wireless communications with the Internet).

[0057] Proceeding to 308, method 300 includes recording vehicle route information during a drive cycle starting from a key-on event. In some examples, the vehicle route information may be divided into one or more segments, wherein the route begins with a key-on event indicating a starting location and ends with a key-off event indicating a final destination (e.g., a threshold proximity of removing the ignition key or fob away from the vehicle, under such conditions, the engine and motor that propel the vehicle may stop rotating). Conversely, a segment may end with a key-off event indicating a temporary destination. A temporary destination may include a key-off event in which the vehicle is turned off for less than a first threshold duration, while a final destination may include a key-off event in which the vehicle is turned off for at least the threshold duration. For example, a driver may stop for coffee on the way to work. The first threshold duration may be a non-zero amount of time (e.g., 1 hour to 3 hours), after which the engine may cool down. However, it should be understood that there may be one or more engine stop / start events during each route segment. Such stop / start events may be recorded, including the duration of each engine-on and engine-off period of the stop / start event, the location where each stop / start event occurs, and the like.

[0058] At 308, the vehicle controller may continuously collect data about the vehicle's operation / condition, location, traffic information, local weather information, etc. from various sensor systems and external sources. This may be accomplished by, for example, GPS (e.g., Figure 1 GPS 132), inertial sensors (e.g., Figure 1Sensors 199), lasers, radars, sonars, acoustic sensors, etc. may be used to collect data. Other feedback signals from sensors such as tire pressure sensors, engine temperature sensors, brake heat sensors, brake pad condition sensors, tire tread sensors, fuel sensors, oil level and quality sensors, engine speed sensors, manifold pressure sensors, etc. may also be read from the vehicle. Still further, at 308, the vehicle controller may also retrieve various types of non-real-time data, such as information from detailed maps, which may be stored at the controller or may be retrieved wirelessly. Thus, during the process of a vehicle traveling along a particular route, data regarding a particular vehicle travel route or trip vector may be obtained and stored at the vehicle controller. Thus, in addition to key-on events and key-off events, segments may also be defined by other route information such as vehicle position, vehicle speed, etc.

[0059] Proceeding to 310, method 300 may include establishing a predicted / learned driving route. For example, multiple trip vectors and corresponding information may be obtained and stored at the vehicle controller so that the driving route can be predicted / learned with high accuracy. The predicted / learned driving route may include routes that are frequently traveled according to a daily, weekly, or monthly schedule (e.g., at typical times of the day and days of the week) and further have common starting locations and final destinations. In some examples, the vehicle may travel (one or more) routes that are not frequently traveled (e.g., not "common"). Therefore, it should be understood that route information that is not significantly related to commonly traveled routes can be periodically forgotten or removed from the vehicle controller to prevent the accumulation of excessive amounts of data related to the vehicle's travel routes.

[0060] In some examples, data collected from vehicle travel routes (including GPS data) can be applied to an algorithm that feeds into one or more machine-learned algorithms to determine common vehicle travel routes. Such examples are intended to be illustrative and not intended to be limiting. For example, a vehicle controller can utilize any common vehicle route learning method to establish a learned travel route without departing from the scope of the present disclosure.

[0061] Learning the travel route at 310 may include determining key-off events between and including the starting destination and the final destination. For example, learning the travel route at 310 may include learning / predicting stops (e.g., vehicle shutoff events) that are typically less than a first threshold duration (e.g., less than 1 hour to 3 hours), and may further include learning / predicting stops that are typically greater than the first threshold duration (e.g., greater than 1-3 hours). Further, learning the travel route at 310 may include determining an expected duration of continuous engine-on activity above idle within a particular route segment and an amount of manifold vacuum achieved during the engine-on activity. As described above and discussed in further detail below, such information may be utilized to determine a route that enables fuel vapor storage canister purging.

[0062] At 312, method 300 includes storing information related to the learned travel route in one or more lookup tables at a vehicle controller. Such information may include, for example, segments of a particular vehicle route, TOD and DOW expected for each route, indications of routes indicating stops, average vehicle speed and peak vehicle speed during the route, learned / predicted duration of continuous engine-on activity above idle for each route segment, and average manifold vacuum and peak manifold vacuum achieved during continuous engine-on activity above idle. Further, the controller may use map and / or GPS data to determine which routes and / or route segments correspond to city driving and which routes and / or route segments correspond to highway driving.

[0063] At 314, method 300 includes identifying a route for fuel vapor storage canister preheating. The route for fuel vapor storage canister preheating may include a route where the engine is on and operated above idle for at least a second threshold duration. The second threshold duration may be a non-zero value less than the first threshold duration described above, and may correspond to a minimum amount of time to complete a fuel vapor storage canister purge event. The second threshold duration may vary based on the manifold vacuum amount, wherein the second threshold duration decreases as the manifold vacuum amount increases. In addition, the route for fuel vapor storage canister preheating may include enabling purging within a predetermined time range after the start of the drive cycle. Therefore, the controller may reference one or more lookup tables with predicted continuous engine on event durations and average manifold vacuum achieved during continuous engine on events to identify routes where fuel vapor purging can occur, and then identify routes for canister preheating based on enabling purging within a predetermined time range. Such identified routes may be stored at the controller, such as in a lookup table. Additionally or alternatively, the identified routes may be stored in the cloud. After 314, method 300 ends.

[0064] As described above, in a hybrid vehicle or a vehicle with a stop / start engine, since the engine is frequently shut down, the evaporative emission system (e.g., Figure 2 The evaporative emissions system 219 of the invention is a fuel vapor storage canister (e.g., Figure 2 The driving routes for purging the fuel vapor storage canister 222 (of the fuel vapor storage canister 222) may be limited. Further, even when canister purging is possible, such as when the conditions for canister purging are met (described below), there may not be enough time to fully heat the fuel vapor storage canister to desorb the heavy fraction of the fuel vapor hydrocarbons before the next engine shutdown. As a result, the fuel vapor storage canister purging may be incomplete, and fuel vapor (particularly the heavy fraction) may escape into the atmosphere as blowdown emissions. Therefore, by identifying a route for preheating the fuel vapor storage canister, the fuel vapor storage canister may be heated in advance so that the fuel vapor storage canister (both the light and heavy fractions therein) can be quickly purged once the purging conditions are met.

[0065] Continue to Figure 4 , which shows an example method 400 for preheating a fuel vapor storage canister. Specifically, when the vehicle is off, in anticipation of an identified travel route for preheating a fuel vapor storage canister, a controller (e.g., Figure 2 The controller 12 of the embodiment activates a tank heating element of the fuel vapor storage tank (e.g., Figure 2 Further, the controller may perform an emissions test on the evaporative emissions system while the vehicle remains off. Thus, even if a fuel vapor storage canister purge does not occur after the fuel vapor storage canister is preheated, the preheating may be used as a diagnostic tool without wasting energy consumed by the canister heating element.

[0066] Method 400 begins at 402 and includes determining whether fuel vapor storage canister preheat conditions are met. For example, after the vehicle is turned off and before the controller enters sleep mode, the controller may determine an identified travel route for fuel vapor storage canister preheat (e.g., regarding Figure 3) is predicted as the next travel route. That is, based on known travel data, the controller may determine that the vehicle is expected to travel in a route that enables fuel vapor storage canister purging after a subsequent vehicle key-on event, such as a route where the engine will remain active for at least a threshold duration (e.g., the second threshold duration described above at 314) in a predetermined time range. The controller may further evaluate the fuel vapor storage canister load and determine whether the fuel vapor storage canister load (e.g., the amount of fuel vapor stored in the fuel vapor storage canister) is greater than or equal to a threshold load. The threshold load may correspond to a non-zero amount of adsorbed fuel vapor below which purging may not be beneficial (e.g., the fuel vapor storage canister does not need to be cleaned). Therefore, the fuel vapor storage canister preheat condition may include the identified travel route for fuel vapor storage canister preheat being predicted as the next travel route, and the fuel vapor storage canister load being at or above the threshold load. The fuel vapor storage canister preheat condition may optionally further include a state of charge (SOC) of an energy storage device (e.g., energy storage device 150) of the vehicle being greater than a threshold SOC. The threshold SOC may be a non-zero charge amount (such as a percentage of total charge capacity) below which the energy storage device may be unable to support or perform additional vehicle functions (such as operating the vehicle in electric mode) at startup. However, if the vehicle is coupled to a fixed power grid or solar energy is available, fuel vapor storage canister preheating may be activated even if the SOC is less than the threshold.

[0067] If the fuel vapor storage canister preheating conditions are not met, such as when the identified driving route for fuel vapor storage canister preheating is not predicted as a subsequent driving route, when the fuel vapor storage canister load is below a threshold, and / or optionally when the energy storage device SOC is less than a threshold SOC, method 400 proceeds to 404 and includes maintaining vehicle operating parameters. For example, the controller may continue to perform shutdown operations and a timer may not be set to wake the controller to perform fuel vapor storage canister preheating. After 404, method 400 ends.

[0068] If the fuel vapor storage canister preheat condition is met, method 400 proceeds to 406 and includes setting a timer to wake the controller before the vehicle is started. For example, for the identified driving route, the timer may be set to wake the controller for a duration (e.g., 10 minutes) before the predicted vehicle key-on event. The duration may be determined based on the size (e.g., mass) of the fuel vapor storage canister (where the duration increases as the size of the fuel vapor storage canister increases), the ambient temperature, forecast weather conditions, the fuel vapor storage canister load, and the known characteristics of the canister heating element (e.g., the achievable heating rate). For example, as the difference between the desired fuel vapor storage canister temperature achieved by preheating and the current (or forecast) ambient temperature increases, the duration may increase. As another example, as the fuel vapor storage canister load increases, the duration may increase because more energy may be expended to raise the temperature of the fuel vapor storage canister as heat is consumed by fuel vapor desorption. Note that if an unexpected controller wakeup occurs, such as when the vehicle is started for an unpredicted trip, the method may return to 402 upon a subsequent vehicle shutdown and re-evaluate whether the fuel vapor storage canister preheat condition is met. Therefore, if the fuel vapor storage canister preheat conditions are not continuing to be met, the timer may be canceled.

[0069] At 408, method 400 includes waking up the controller. For example, when the timer expires, the controller may return (e.g., transition) to the wake-up mode. If the vehicle is a plug-in HEV, grid power (e.g., from Figure 1 If the vehicle includes a solar cell (e.g., Figure 1 solar cell 108) and solar energy is available, the solar energy can be used to power the controller (e.g., from Figure 1 The solar battery 30 and / or charge controller 32 of the energy storage device can be used for power supply. Therefore, the controller can be powered by energy from the energy storage device only when an alternative power source is not available.

[0070] At 410 , method 400 includes commanding closing of a tank vent valve (eg, Figure 2 The CVV 214 of the canister is closed and activates a canister heating element that couples the fuel vapor storage canister to the atmosphere. By closing the CVV, pressure may build up in the evaporative emissions system as fuel vapor desorbs from the heated fuel vapor storage canister. Further, with the CVV closed, venting emissions may not occur. Activating the canister heating element may include supplying electrical power to the canister heating element such that the canister heating element generates heat that can then be transferred to the fuel vapor storage canister, including an adsorbent within the fuel vapor storage canister. The evaporative emissions system may be configured to provide ... evaporative emissions system is configured to provide electrical power to the canister heating Figure 2The amount of power supplied to the tank heating element may be modulated based on the temperature of the fuel vapor storage canister as measured by temperature sensor 215 of the fuel vapor storage canister. For example, a relatively high amount (or duty cycle) of power may be initially supplied to the tank heating element in order to quickly raise the temperature of the fuel vapor storage canister to a desired temperature (e.g., 150° F). Then, once the fuel vapor storage canister reaches the desired temperature, the amount of power (or duty cycle) supplied to the tank heating element may be reduced in order to maintain the temperature of the fuel vapor storage canister at the desired temperature. For example, the controller may input the temperature of the fuel vapor storage canister, the ambient temperature, and the mass of the fuel vapor storage canister into a lookup table or function and output the amount of power (or duty cycle) to be supplied to the tank heating element.

[0071] At 412 , method 400 includes determining whether the canister heating element is functional. For example, if the canister heating element is functional, the temperature of the fuel vapor storage canister is expected to increase. Therefore, determining whether the canister heating element is functional may include measuring the temperature of the fuel vapor storage canister using a temperature sensor coupled to the fuel vapor storage canister. Alternatively, a hydrocarbon (HC) sensor (e.g., Figure 2 HC sensor 213) may be used to determine whether the canister heating element is functional. For example, if the canister heating element is functional, fuel vapor may desorb from the adsorbent of the fuel vapor storage canister when the fuel vapor storage canister is heated. However, if the canister heating element is inoperative, fuel vapor may not desorb from the adsorbent.

[0072] Thus, if the temperature of the fuel vapor storage canister does not increase by at least a threshold amount and / or if the HC sensor does not detect fuel vapor (e.g., gaseous HC) within a predetermined duration (e.g., 5 minutes) after the canister heating element is activated, it can be determined that the canister heating element is not functional and method 400 proceeds to 414. At 414, method 400 includes indicating that the canister heating element is degraded. Indicating that the canister heating element is degraded may include setting a corresponding diagnostic problem code (DTC) at the controller. In addition, a malfunction indicator light (MIL), for example, may be illuminated on the instrument panel of the vehicle to alert the vehicle operator to service the vehicle, and may further include indicating a reason for the MIL. As described below, purging may still occur even if the canister heating element is degraded. However, in the event that the fuel vapor storage canister is not heated by the canister heating element, heavy fractions may remain adsorbed to the adsorbent of the fuel vapor storage canister and may not be purged.

[0073] Conversely, if the temperature of the fuel vapor storage canister increases by at least a threshold amount and / or if the HC sensor detects fuel vapor (e.g., gaseous HC) within a predetermined duration after the canister heating element is activated, it may be determined that the canister heating element is functional and method 400 proceeds to 416. At 416, method 400 includes monitoring the pressure of the evaporative emissions system for a duration. The duration may be a predetermined duration within which a pressure increase due to desorption of fuel vapor from the fuel vapor storage canister is expected. The pressure in the evaporative emissions system may be detected by a pressure sensor such as a Figure 2 However, in the case where the fuel tank isolation valve is not included (e.g., the Figure 2 In other examples of FTIV 236, a fuel tank pressure sensor (such as Figure 2 The FTPT 217) measures the pressure of both the fuel system and the evaporative emissions system.

[0074] At 418, it is determined whether the pressure is greater than a threshold pressure. The threshold pressure may be a non-zero positive pressure amount above atmospheric (e.g., ambient) pressure, and when above the non-zero positive pressure amount, it may be determined that fuel vapor is not released from the evaporative emissions system. The threshold may vary based on the fuel vapor storage canister load before the fuel vapor storage canister is heated, wherein the threshold increases as the fuel vapor storage canister load increases. For example, before the CVV is closed and the canister heating element is activated (e.g., at 410), the evaporative emissions system may be balanced with atmospheric pressure. Then, when the fuel vapor is desorbed due to the heating of the fuel vapor storage canister, the pressure of the sealed evaporative emissions system is expected to increase, wherein when the fuel vapor storage canister load is greater, the pressure increases further (and therefore, more fuel vapor may be used for desorption). If the pressure is greater than the threshold, method 400 proceeds to 420 and includes indicating that no degradation is detected in the evaporative emissions system. Then, method 400 may proceed to 422, as described below.

[0075] If at 418 the pressure is not greater than a threshold, such as when the pressure is less than or equal to the threshold, method 400 proceeds to 421 and includes indicating that degradation is detected in the evaporative emissions system. For example, in the event that the canister heating element is confirmed to be functional (and the fuel vapor storage canister load is greater than a threshold load), the lack of sufficient pressure increase in the evaporative emissions system indicates that pressure (and fuel vapor) may escape through an orifice (e.g., a hole or disconnection between components) to the atmosphere, thereby causing increased vehicle emissions. Indicating evaporative emissions system degradation may include setting a corresponding DTC at the controller. Additionally, the MIL may be illuminated, for example, on the instrument panel of the vehicle to remind the vehicle operator to service the vehicle, and may further include indicating the reason for the MIL.

[0076] At 423, method 400 includes disabling extraction. For example, if the fuel vapor storage canister is purged when the orifice is present in the evaporative emissions system, unmetered air may enter through the orifice, thereby causing the engine to run lean. Therefore, extraction may be disabled before the vehicle is serviced and the DTC is eliminated. However, in other examples, extraction may be re-enabled based on the results of one or more subsequent evaporative emissions system diagnostic tests. For example, a subsequent blowdown test may be performed, in which the evaporative emissions system is evacuated, sealed, and then the pressure increase (e.g., blowdown) is measured over a period of time. If the blowdown test indicates that the orifice is large (e.g., greater than a threshold diameter), such as when the rate of pressure increase is greater than a threshold rate, extraction may remain disabled before the DTC is eliminated. The threshold diameter may correspond to a non-zero diameter, and when it is above the non-zero diameter, the unmetered air inhaled through the orifice may cause the engine to run significantly lean, which may degrade engine performance. If the blowdown test indicates that the orifice is small (e.g., less than or equal to a threshold diameter), such as when the rate of pressure increase is less than or equal to a threshold rate, purging may be re-enabled because the amount of air that may be drawn through the orifice may not be sufficient to cause the engine to operate significantly lean. As such, as described below, purging may be performed in response to satisfying purging conditions. By purging the fuel vapor storage canister after re-enabling purging even when evaporative emissions system degradation is detected in some examples, fuel vapors may be effectively directed to the engine intake system rather than released into the atmosphere as undesirable evaporative emissions. After 423, method 400 ends.

[0077] At 422, method 400 includes determining whether purging conditions are met. Once the drive cycle begins, the controller may begin monitoring whether purging conditions are met. Purge conditions may include using torque from the engine to propel the vehicle (e.g., the vehicle is on and the engine is on and operating above idle). Purge conditions may further include an indication that manifold pressure (e.g., MAP) is less than atmospheric pressure by a predetermined threshold amount (e.g., manifold vacuum is greater than a threshold vacuum), thereby indicating that sufficient manifold vacuum exists to draw desorbed fuel vapor into the engine intake.

[0078] If the extraction condition is not met, the method 400 proceeds to 424 and includes determining whether a threshold duration has passed. The threshold duration may account for, for example, that the first segment of the driving route cannot be extracted and / or for slight changes in driving activity. As an example, the threshold duration may be determined at least in part based on the standard deviation of the average start time of the identified driving route. For example, if the start time is 8:30 and the standard deviation is 5 minutes, the threshold duration may be set to 5 minutes. As another example, the threshold duration may be a fixed predetermined duration (e.g., a predetermined time range) for all identified driving routes. In a non-limiting example, the threshold duration may be in the range of 10 minutes to 15 minutes. In yet another example, the threshold duration may be a predetermined duration (e.g., 10 minutes to 15 minutes) further adjusted based on a known variance (such as a standard deviation) of the identified route start time and / or based on route traffic (e.g., route traffic may cause the vehicle to be turned on but the engine is turned off) or other identified factors that may prevent the extraction condition from being met. In other examples, the predetermined duration may be the distance traveled by the vehicle. Further, in some examples, the threshold duration can be adjusted based on the SOC of the energy storage device. For example, when the SOC of the energy storage device is less than a threshold SOC and the vehicle power generation capacity (e.g., obtained via a generator and / or solar cell) is less than the power generation capacity required to provide a desired charging rate, the threshold duration can be reduced.

[0079] If the threshold duration has not passed, method 400 may return to 422 and the controller may continue to satisfy indications of monitoring purging conditions. If the threshold duration has passed, method 400 proceeds to 426 and includes deactivating the tank heating element. As the threshold duration passes, it may be assumed that the purging condition may not occur as expected. As an example, the vehicle may remain stationary without traveling the identified route. Therefore, continuing to heat the fuel vapor storage canister is not beneficial and may consume power unnecessarily. However, if the solar cell provides sufficient charge to maintain fuel vapor storage canister heating, or if the vehicle's electric motor has the capacity to generate sufficient charge from engine power to maintain fuel vapor storage canister heating, fuel vapor storage canister heating may continue even after the duration has been exceeded. For example, deactivating the tank heating element may include stopping power to the tank heating element.

[0080] At 428, method 400 optionally includes putting the controller to sleep. For example, if the vehicle remains off, the controller may be put to sleep. Thus, the controller remaining on may unnecessarily consume power. However, if the vehicle is on and / or if the controller is performing other (non-preheating) functions (such as other diagnostic procedures, transmitting data, etc.), the controller may not be put to sleep. After 428, method 400 ends.

[0081] Returning to 422, if purging conditions are met, such as when the vehicle is on and being propelled by engine torque and the manifold pressure is less than a threshold, method 400 proceeds to 430 and includes commanding opening of a tank purge valve (CPV) (such as Figure 2 The CPV 212 of the fuel vapor storage canister is commanded to open and the CVV is commanded to open to purge the contents of the fuel vapor storage canister (and fuel vapor desorbed from the evaporative emissions system) to the engine intake. Further, if a FTIV is included, purging the fuel vapor storage canister may include maintaining the FTIV closed. By commanding the CPV to open with the CVV open (and the FTIV closed), fresh air may be drawn across the fuel vapor storage canister, thereby desorbing adsorbed hydrocarbons from the fuel vapor storage canister. The desorbed hydrocarbons may be directed to the engine intake via the open CPV for combustion. Thus, at 432, method 400 may optionally include monitoring the purge flow. For example, one or more exhaust gas oxygen sensors (e.g., Figure 2 An exhaust gas oxygen sensor 226 ) may be positioned in the engine exhaust system to provide an estimate of the amount of fuel vapor purged to the engine intake system. Alternatively, a sensor coupled to the engine intake system, such as an intake oxygen sensor, may provide an indication of the amount of fuel vapor purged to the engine intake. The purge flow rate may be determined based on the fuel vapor storage canister load and further based on engine operating conditions, such as engine speed-load conditions. Note that if it is determined that the canister heating element is degraded (e.g., at 412 ), the light fraction may be purged while the heavy fraction may remain adsorbed in the fuel vapor storage canister. If it is determined that the canister heating element is functional, both the light fraction and the heavy fraction may be purged.

[0082] At 434 , method 400 includes determining whether the purge event is complete. For example, the purge event may be complete when the fuel vapor storage canister load reaches a lower threshold fuel vapor storage canister load. The lower threshold fuel vapor storage canister load may refer to a fuel vapor storage canister load at which it may be determined that the fuel vapor storage canister is sufficiently clean and capable of adsorbing more fuel vapor, such as during a subsequent refueling event. The lower threshold fuel vapor storage canister load may vary depending on whether the canister heating element is functional, as determined at 412 . For example, if it is determined that the canister heating element is functional, the lower threshold fuel vapor storage canister load may be lower, and if it is determined that the canister heating element is degraded, the lower threshold fuel vapor storage canister load may be higher because heavy fractions may remain adsorbed.

[0083] If it is determined at 434 that the fuel vapor storage canister purge is not complete, method 400 proceeds to 436 to continue purging the contents of the fuel vapor storage canister into the engine intake system. However, if it is determined at 434 that the purge event is complete, method 400 proceeds to 438 and includes commanding the CPV to close to stop purging. By commanding the CPV to close, the fuel vapor storage canister may be isolated from the engine intake system.

[0084] At 440 , method 400 includes deactivating the canister heating element. With the purge event complete, it is no longer beneficial to maintain the temperature of the fuel vapor storage canister at a desired temperature. As described above, deactivating the canister heating element may include stopping power to the canister heating element.

[0085] At 442, method 400 includes updating the evaporative emissions system status. For example, updating the evaporative emissions system status may include indicating that the fuel vapor storage canister has been purged of stored fuel vapor. More specifically, if it is determined that the canister heating element is functional, it may indicate that the fuel vapor storage canister has been purged of both the HC light fraction and the HC heavy fraction, or if it is determined that the fuel vapor storage canister is degraded, it may indicate that the fuel vapor storage canister has been purged of the HC light fraction. For example, such an indication may be stored in a controller. Updating the evaporative emissions system status may additionally include updating a fuel vapor storage canister purge schedule. For example, in response to an indication that the fuel vapor storage canister has been sufficiently purged of both the HC light fraction and the HC heavy fraction, a future fuel vapor storage canister purge operation may be postponed or rescheduled. After 442, method 400 ends.

[0086] Thus, in one example, the method may include determining a first key-off event (e.g., a first vehicle shutdown), and in response thereto, setting a timer to wake up a controller of the vehicle to actuate a canister heating element coupled to the fuel vapor storage canister; and determining a second key-off event (e.g., a second vehicle shutdown, which may not be the first vehicle shutdown), and in response thereto, not setting a timer to wake up the controller. For example, the first key-off event may correspond to a key-off event that indicates preheating of the fuel vapor storage canister, such as when a driving route that will enable fuel vapor storage canister purging is predicted as a subsequent driving route and a load of the fuel vapor storage canister is greater than a threshold load. The second key-off event may correspond to a condition that does not indicate preheating of the fuel vapor storage canister, such as when a driving route that will enable fuel vapor storage canister purging is not predicted as a subsequent driving route and / or a load of the fuel vapor storage canister is less than a threshold load. Thus, in some examples, setting a timer to wake up the controller to actuate the canister heating element occurs in the absence of the second key-off event and / or at or during the first key-off event. The second key-off event may not be present during the first key-off event, and the first key-off event may not be present during the second key-off event. However, when the vehicle is turned off, there is one of a first key-off event and a second key-off event.

[0087] Further, the instructions stored in the memory may include determining a first key-off event based on data stored at a memory of the controller (such as data regarding a route traveled by the vehicle) and further based on an indication that the vehicle is shutting down (e.g., as indicated by an ignition switch position). In response to determining the first key-off event, the instructions stored in the memory may actuate a timer function to wake the controller within a determined duration prior to a predicted start time of a subsequent drive cycle. In response to the controller transitioning from a sleep mode to a wake mode once the timer time has elapsed, the tank heating element may be actuated by instructions for sending a signal to the tank heating element. In some examples, the method may include determining whether to perform one or more of setting a timer to wake the controller and activating the tank heating element based on determining whether the first key-off event exists and determining whether the second key-off event exists.

[0088] Next go to Figure 5 , which shows vehicle systems (e.g., Figure 2 Example timeline 500 of vehicle system 206 parameters. Figure 3 After identifying the driving route for preheating the fuel vapor storage tank, the method can be used according to Figure 4 Method for preheating a fuel vapor storage tank (e.g., Figure 2Further, while the fuel vapor storage canister is warmed up, an evaporative emissions system test may be performed due to pressure generated by desorption of fuel vapor from the fuel vapor storage canister.

[0089] Example timeline 500 shows the engine operating in a stop / start mode, but the methods described herein may also be used with other operating modes (such as when the vehicle switches between an engine-only operating mode and an electric-only operating mode). Vehicle state is shown in curve 502, engine state is shown in curve 504, vehicle speed is shown in curve 506, fuel vapor storage canister load is shown in curve 508, and fuel vapor storage canister temperature (T canister ) is shown in curve 510, the evaporative emissions system pressure (P evap_sys ) is shown in curve 512, the CVV position is shown in curve 514, the CPV position is shown in curve 516, an indication of whether the tank heating element is on or off is shown in curve 518, and an indication of whether the extraction condition is met is shown in curve 520. For all of the above curves, the horizontal axis represents time, where time increases from left to right along the horizontal axis. The vertical axis represents each labeled parameter, where the value increases from bottom to top, except that in curves 502, 504, and 518, the vehicle, engine, and tank heating element are indicated as "on" or "off", respectively; in curves 514 and 516, the CVV and CPV are indicated as "on" or "off", respectively; and in curve 520, whether the extraction condition is met is indicated as "yes" or "no". Additionally, dashed line 522 represents a first, higher threshold fuel vapor storage canister load above which fuel vapor storage canister preheating may be beneficial, dashed line 524 represents a second, lower threshold fuel vapor storage canister load at which the fuel vapor storage canister may be considered clean, dashed line 526 represents an optimal fuel vapor storage canister operating temperature (e.g., a desired temperature), dashed line 528 represents a threshold pressure above which no degradation is indicated in the evaporative emissions system, and dashed line 530 represents atmospheric pressure.

[0090] Prior to time t1, the vehicle is off (plot 502), and therefore the engine is also off (plot 504). With the vehicle off (e.g., the engine is not rotating and the electric propulsion device (if present) is deactivated or not powered), the vehicle is at rest (plot 506). The temperature of the fuel vapor storage canister (plot 510) may be at ambient temperature. Further, during the CVV (e.g., Figure 2 When the CVV 214 of FIG. 1 is opened (curve 514 ) to couple the fuel vapor storage canister to the atmosphere, the evaporative emissions system (eg, Figure 2The pressure of the evaporative emission system 219 is at atmospheric pressure (dashed line 530), as shown by curve 512. In a CPV (e.g., Figure 2 When the CPV 212 of the engine is closed (curve 516), the evaporative emission system maintains contact with the engine's intake device (e.g., Figure 2 In addition, when the fuel vapor storage canister load (curve 508) is above the first higher threshold fuel vapor storage canister load (dashed line 522), the fuel vapor storage canister preheating condition is met. In response to the identified driving route for fuel vapor storage canister preheating being expected as the next driving route, the fuel vapor storage canister preheating condition may be met before time t1, and a timer may be set to wake up the controller for the fuel vapor storage canister preheating event, such as with respect to Figure 3 and Figure 4 described.

[0091] At time t1, the timer expires after a predetermined duration and wakes up the controller. In response, the controller closes the CVV (plot 514) to seal the evaporative emissions system and activates the canister heating element (e.g., Figure 2 The tank heating element 216 is shown as curve 518. In the event that the tank heating element is activated, such as by a temperature sensor coupled to the fuel vapor storage canister (e.g., Figure 2 The temperature of the fuel vapor storage canister measured by the temperature sensor 215 of the fuel vapor storage canister increases (curve 510), indicating that the canister heating element is functional. In the event that the canister heating element is functional, the pressure of the sealed evaporative emissions system may be monitored as an emissions test. For example, the pressure sensor coupled to the evaporative emissions system (such as Figure 2 As fuel vapor desorbs from the fuel vapor storage canister and exceeds a threshold pressure (dashed line 528) between time t1 and time t2, the pressure of the evaporative emissions system increases to above atmospheric pressure (curve 512), indicating that there is no degradation in the evaporative emissions system.

[0092] At time t2, the vehicle is turned on (curve 502), such as in response to a key-on event. The engine is also started (curve 504). The controller may then begin checking whether the purging condition is met. The vehicle is initially driven at a relatively low vehicle speed for two short durations (curve 506). Each time the vehicle speed (curve 506) reaches zero, such as when the vehicle is stopped at a red light, the engine is shut down (curve 504) and restarted in response to a request for torque (e.g., from a vehicle operator). Further, the controller may anticipate these initial engine shutoffs and low vehicle speeds based on data stored on a memory of the controller regarding the route the vehicle is traveling. Therefore, the purging condition (curve 520) may not be met due to the engine shutoff event. However, in the event that the purging condition is expected to be met for less than a threshold duration, the tank heating element may remain on (curve 518) to maintain the fuel vapor storage tank temperature (curve 510) at an optimal operating temperature (dashed line 526), ​​where the threshold duration is determined based on the route being traveled (as referenced in FIG. 5 ). Figure 4 described above).

[0093] Prior to time t3, the vehicle speed (curve 506) increases, such as due to the vehicle being driven on a highway. Further, the controller may anticipate a highway segment of the route of travel based on data stored at the controller. At time t3, a purge condition is met (curve 520), such as in response to manifold vacuum being greater than a threshold manifold vacuum, anticipating engine continued operation for at least a threshold duration that would allow for full purge, etc. In response to the purge condition being met, both the CVV (curve 514) and the CPV (curve 516) are commanded to open. Vacuum from the naturally aspirated engine removes desorbed fuel vapor (including both hydrocarbon heavy fractions and light fractions) through a purge line (e.g., Figure 2 5. The evaporative emissions system is drawn into the engine intake via purge line 228 of FIG. 5. As a vacuum is pulled on the evaporative emissions system, the pressure of the evaporative emissions system is reduced to below atmospheric pressure (curve 512). During the purge event, the fuel vapor storage canister load (curve 508) decreases and reaches a second lower threshold fuel vapor storage canister load (dashed line 524) at time t4. Therefore, it is determined that the fuel vapor storage canister is sufficiently cleaned of adsorbed hydrocarbons, thereby increasing the fuel vapor storage canister adsorption capacity for future fuel vapor storage canister hydrocarbon adsorption events, and the purge conditions are no longer met (curve 520). As a result, the CPV is commanded to close (curve 516), and the evaporative emissions system pressure (curve 512) may begin to equilibrate with atmospheric pressure (dashed line 530). Additionally, as the purge event is completed, the canister heating element is deactivated (curve 518). As a result, the temperature of the fuel vapor storage canister may begin to decrease (curve 510).

[0094] At time t5, the highway segment of the vehicle's driving route is completed and the city driving segment of the driving route begins. The city driving segment includes relatively low vehicle speeds (plot 506) and frequent engine shut-off events (plot 504), while the vehicle is stopped prior to a vehicle key-off event at time t6 (when both the engine and vehicle are shut off). Such frequent engine shut-off events do not provide conditions for a complete fuel vapor storage canister purge. In addition, if the fuel vapor storage canister has not been preheated prior to vehicle start, such as if the canister heating element remains off prior to vehicle start (dashed line segment 518a), the temperature of the fuel vapor storage canister may have reached the optimal operating temperature only shortly before the end of the highway driving segment, as shown by dashed line segment 510a. This may have prevented the fuel vapor storage canister from being adequately cleaned, thereby reducing the fuel vapor storage canister adsorption capacity for subsequent hydrocarbon adsorption events (such as during refueling). Therefore, by preheating the fuel vapor storage canister prior to starting the vehicle at time t2 , both the hydrocarbon heavy fraction and the light fraction may be purged to the engine intake even though purging opportunities are limited due to frequent engine shut-off events.

[0095] In this way, a fuel vapor storage canister included in a vehicle system that operates in a mode in which the engine is frequently shut down, such as a stop / start operating mode, can be effectively cleaned. In particular, by preheating the fuel vapor storage canister, the extraction of heavy hydrocarbon fractions can be accelerated once the extraction conditions are met. In this way, emissions emitted by the vehicle can be reduced. In addition, by preheating the fuel vapor storage canister only when it is expected that a driving route will be able to be purged, energy can be saved. Still further, by performing emissions testing during fuel vapor storage canister preheating, energy can be further saved by utilizing the increased pressure that occurs when fuel vapor is desorbed from the adsorbent in the fuel vapor storage canister. In this way, even if purging does not occur as expected, the energy consumed by preheating the fuel vapor storage canister is used in emissions testing.

[0096] The technical effect of preheating the fuel vapor storage canister when the vehicle is turned off in anticipation of conditions enabling fuel vapor storage canister purging is that fuel vapor storage canister cleaning may be accelerated and hydrocarbon heavy fractions may be purged efficiently.

[0097] As an example, an evaporative emissions method includes: preheating a fuel vapor storage canister in an evaporative emissions system of a vehicle to a desired temperature for a determined duration before starting a drive cycle while the vehicle remains off; and purging vapor stored in the fuel vapor storage canister to an intake of an engine of the vehicle after the drive cycle begins. In the foregoing examples, additionally or optionally, the drive cycle includes a known drive cycle during which purging is enabled, and wherein purging occurs during the drive cycle. In any or all of the foregoing examples, additionally or optionally, the duration is determined based on ambient temperature, a size of the fuel vapor storage canister, and a load of the fuel vapor storage canister. In any or all of the foregoing examples, additionally or optionally, preheating the fuel vapor storage canister includes waking a controller of the vehicle from a sleep mode for the determined duration, and then the controller actuating a canister heating element coupled to the fuel vapor storage canister. In any or all of the foregoing examples, the method additionally or optionally further includes: in response to an indication that the canister heating element is active, performing an emissions test on the evaporative emissions system before purging. In any or all of the foregoing examples, additionally or optionally, the purging occurs within a threshold duration after the start of the drive cycle, and the indication that the canister heating element is functional includes at least one of: a temperature of the fuel vapor storage canister reaches a threshold temperature within a predetermined duration shorter than the threshold duration, and a hydrocarbon sensor coupled to the evaporative emissions system detects desorbed fuel vapor within the predetermined duration. In any or all of the foregoing examples, additionally or optionally, the purging occurs within a threshold duration after the start of the drive cycle, and performing an emissions test on the evaporative emissions system includes measuring a pressure of the evaporative emissions system within a second predetermined time shorter than the threshold duration, and the method additionally or optionally further includes: in response to the pressure of the evaporative emissions system reaching a threshold pressure within the second predetermined duration, indicating that no degradation is detected in the evaporative emissions system; and in response to the pressure of the evaporative emissions system not reaching the threshold pressure within the second predetermined duration, indicating that degradation is detected in the evaporative emissions system. In any or all of the foregoing examples, the method additionally or optionally further includes preheating the fuel vapor storage canister via energy from a grid or solar panel external to the vehicle.

[0098] As another example, an evaporative emissions method includes: setting a timer to wake up a controller of a vehicle to preheat a fuel vapor storage canister before an expected vehicle key-on event that occurs after a first key-off event and before the controller transitions to a sleep mode; and not setting a timer to preheat the fuel vapor storage canister after a second key-off event and before the controller transitions to a sleep mode. In the foregoing examples, additionally or optionally, a timer is set for preheating the fuel vapor storage canister when an identified travel route for preheating the fuel vapor storage canister is expected after the expected vehicle key-on event, and when a fuel vapor load of the fuel vapor storage canister is greater than a threshold load. In any or all of the foregoing examples, additionally or optionally, a timer is set for a determined duration before the expected vehicle key-on event. In any or all of the foregoing examples, the method additionally or optionally further includes: after the timer has expired and the controller has been woken up: actuating a canister heating element coupled to the fuel vapor storage canister; commanding closure of a canister vent valve in a vent line that couples the fuel vapor storage canister to atmosphere; and monitoring a pressure of the evaporative emissions system. In any or all of the foregoing examples, the method additionally or optionally further includes: in response to the pressure of the evaporative emissions system not reaching a threshold pressure within a determined duration, indicating degradation of the evaporative emissions system. In any or all of the foregoing examples, additionally or optionally, further in response to the temperature of the fuel vapor storage canister reaching or exceeding a threshold temperature within a determined duration, indicating the presence of degradation in the evaporative emissions system. In any or all of the foregoing examples, the method additionally or optionally further includes: after an expected vehicle key-on event, in response to satisfying a purge condition, purging fuel vapor from the evaporative emissions system to an engine intake of the vehicle. In any or all of the foregoing examples, additionally or optionally, the purge condition includes the vehicle being propelled by the engine and an amount of vacuum in the engine intake being greater than a threshold vacuum. In any or all of the foregoing examples, additionally or optionally, the purging includes commanding opening of a fuel vapor storage canister vent valve and a fuel vapor storage canister purge valve in a purge line that couples the evaporative emissions system to the engine intake.

[0099] As a third example, a system for a vehicle includes: an engine system, which includes an engine configured to propel the vehicle by burning air and fuel; a fuel system, which includes a fuel tank for storing fuel; an evaporative emissions system, which is fluidly connected to the fuel system and an intake device of the engine via a purge line, the evaporative emissions system including a fuel vapor storage canister; a canister heating element coupled to the fuel vapor storage canister; a canister vent valve positioned in an exhaust line of the evaporative emissions system; a canister purge valve positioned in the purge line; and a controller storing instructions in a non-volatile memory, the instructions, when executed, causing the controller to perform the following operations: waking from a sleep mode and activating the canister heating element for a duration before an expected vehicle start when the vehicle is first shut down; and remaining in the sleep mode when the vehicle is second shut down. In the foregoing examples, additionally or optionally, during a first vehicle shutdown, after an anticipated vehicle start, the predicted travel route enables purging of the fuel vapor storage canister and predicts a load of the fuel vapor storage canister greater than a threshold load; and during a second vehicle shutdown, after an anticipated vehicle start, predicts at least one of: the travel route does not enable purging of the fuel vapor storage canister and the load of the fuel vapor storage canister is less than or equal to the threshold load. In any or all of the foregoing examples, additionally or optionally, the predicted travel route is known based on data collected while the vehicle is traveling.

[0100] In another representation, a method includes: distinguishing between a first vehicle key-off condition and a second vehicle key-off condition; setting a timer to wake a controller in response to the first vehicle key-off condition; and maintaining the controller in a sleep mode in response to the second vehicle key-off condition. In the foregoing examples, additionally or optionally, the distinguishing includes selecting between the first vehicle key-off condition and the second vehicle key-off condition based on one or more of an expected driving route after a subsequent vehicle key-on event and a fuel vapor load of a fuel vapor storage canister. In any or all of the foregoing examples, additionally or optionally, the first vehicle key-off condition is selected when a driving route that enables purging of the fuel vapor storage canister is an expected driving route, and the second vehicle key-off condition is selected when a driving route that does not enable purging of the fuel vapor storage canister is an expected driving route. In any or all of the foregoing examples, additionally or optionally, the first vehicle key-off condition is selected when the fuel vapor load of the fuel vapor storage canister is above a threshold load, and the second vehicle key-off condition is selected when the fuel vapor load of the fuel vapor storage canister is less than or equal to the threshold load. In any or all of the foregoing examples, the method additionally or optionally further includes: after waking the controller in response to selecting the first vehicle key-off condition, actuating a canister heating element coupled to the fuel vapor storage canister. In any or all of the foregoing examples, additionally or optionally, setting a timer for a determined duration prior to a subsequent vehicle key-on event. In any or all of the foregoing examples, additionally or optionally, determining the timing of the subsequent vehicle key-on event based on travel route data stored in a memory of the controller.

[0101] Note that the example control and estimation programs included herein can be used with various engine and / or vehicle system configurations. The control methods and programs disclosed herein can be stored in non-transitory memory as executable instructions, and can be performed by a control system including a controller in combination with various sensors, actuators and other engine hardware. The specific program described herein may represent one or more of any number of processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). In this regard, the various actions, operations and / or functions shown may be performed in the sequence shown, performed simultaneously or omitted in some cases. Similarly, the processing order is not necessary to achieve the features and advantages of the example embodiments described herein, but is provided for ease of illustration and description. One or more of the actions, operations and / or functions shown may be repeated depending on the specific strategy used. Further, the described actions, operations and / or functions may be graphically represented as codes in the non-transitory memory of a computer-readable storage medium to be programmed into an engine control system, wherein the described actions are performed by executing instructions in a system including various engine hardware components and an electronic controller.

[0102] 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 technology can be applied to V-6, I-4, I-6, V-12, opposed 4 cylinders, 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 properties disclosed herein.

[0103] The appended claims particularly point out certain combinations and subcombinations regarded as novel and non-obvious. These claims may refer to "an" element or a "first" element or their equivalent. Such claims should be understood to include incorporation of one or more such elements, neither requiring nor excluding two or more such elements. Other combinations and subcombinations of the disclosed features, functions, elements, and / or properties may be claimed by amendment of the present claims or by presentation of new claims in this or a related application. Such claims, whether broader, narrower, equal, or different in scope to the original claims, are deemed to be included in the subject matter of the present disclosure.

Claims

1. An evaporative emissions method comprising: when the vehicle remains off, waking from a sleep mode prior to commencing a drive cycle and preheating a fuel vapor storage canister in an evaporative emissions system of said vehicle to a desired temperature within a determined duration; upon awakening from the sleep mode, commanding closing of a canister purge valve positioned in a purge line of the evaporative emissions system, maintaining closed a canister purge valve positioned in a purge line, and monitoring a pressure of the evaporative emissions system; as well as After the drive cycle begins, vapors stored in the fuel vapor storage canister are purged into an intake of an engine of the vehicle.

2. The method of claim 1, wherein the drive cycle comprises a known drive cycle during which the extracting is enabled, and wherein the extracting occurs during the drive cycle. 3 . The method of claim 1 , wherein the determined duration is based on an ambient temperature, a size of the fuel vapor storage canister, and a load of the fuel vapor storage canister. 4 . The method of claim 1 , wherein preheating the fuel vapor storage canister includes waking a controller of the vehicle from a sleep mode within the determined duration, the controller then actuating a canister heating element coupled to the fuel vapor storage canister. 5 . The method of claim 4 , further comprising, in response to the indication that the canister heating element is functional, performing an emissions test on the evaporative emissions system prior to the purging.

6. The method of claim 5 , wherein the purging occurs within a threshold duration after the start of the drive cycle, and wherein the indication that the canister heating element is active includes at least one of: a temperature of the fuel vapor storage canister reaching a threshold temperature within a predetermined duration that is shorter than the threshold duration, and a hydrocarbon sensor coupled to the evaporative emissions system detecting desorbed fuel vapor within the predetermined duration.

7. The method of claim 5, wherein the purging occurs within a threshold duration after the start of the drive cycle, and wherein performing the emissions test on the evaporative emissions system includes measuring a pressure of the evaporative emissions system for a second predetermined duration that is shorter than the threshold duration.

8. The method according to claim 7, further comprising: responsive to the pressure of the evaporative emissions system reaching a threshold pressure within the second predetermined duration, indicating that no degradation is detected in the evaporative emissions system; as well as In response to the pressure of the evaporative emissions system not reaching the threshold pressure within the second predetermined duration, degradation is indicated as being detected in the evaporative emissions system. 9 . The method of claim 1 , further comprising preheating the fuel vapor storage canister via energy from a grid or solar panels external to the vehicle.

10. A system for a vehicle, comprising: an engine system including an engine configured to propel the vehicle by combusting air and fuel; a fuel system comprising a fuel tank for storing said fuel; an evaporative emissions system in fluid communication with the fuel system and an air intake of the engine via a purge line, the evaporative emissions system including a fuel vapor storage canister; a canister heating element coupled to the fuel vapor storage canister; a canister vent valve positioned in an exhaust line of the evaporative emissions system; a tank extraction valve positioned in the extraction line; as well as A controller stores instructions in a non-volatile memory, wherein the instructions, when executed, cause the controller to perform the following operations: awakening from a sleep mode and activating the tank heating element for a duration when the vehicle is first shut down and prior to an anticipated vehicle start; upon awakening from the sleep mode, commanding closing of the canister vent valve, maintaining closing of the canister purge valve, and monitoring pressure of the evaporative emissions system; and The sleep mode is maintained when the vehicle is shut down a second time.

11. The system of claim 10 wherein during the first vehicle shutdown, after the anticipated vehicle start, a predicted travel route enables purging of the fuel vapor storage canister and a predicted load of the fuel vapor storage canister is greater than a threshold load.

12. The system of claim 11 wherein during the second vehicle shutdown, after the anticipated vehicle start, at least one of: a driving route that does not permit purging of the fuel vapor storage canister, and the load of the fuel vapor storage canister is less than or equal to the threshold load is predicted.

13. The system of claim 12, wherein the predicted driving route is learned based on data collected while the vehicle is traveling.

14. The system of claim 10, wherein the controller stores the following instructions in a non-volatile memory, which instructions, when executed, cause the controller to perform the following operations: After the anticipated vehicle start, fuel vapor is purged from the evaporative emissions system to the intake of the engine in response to purging conditions being satisfied. 15 . The system of claim 14 , wherein the purging condition includes the vehicle being propelled by the engine and an amount of vacuum in the intake of the engine being greater than a threshold vacuum.

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