Vehicle climate control system

Abstract

A vehicle climate control system may include a coolant subsystem configured to circulate coolant between an engine, a heat generator, and a cabin heat exchanger, and a controller. The controller may be configured to delay engine spark timing to increase heat generation in response to an air inlet temperature of the heat exchanger exceeding a threshold. The threshold may be defined by a quotient of (i) a difference between an exhaust temperature target and the air inlet temperature and (ii) a heat efficiency parameter based on air flow rate and coolant flow rate.

Description

Technical Field

[0001] The present application relates generally to climate control systems for vehicles. Background Art

[0002] Conventional vehicles and some electrified vehicles, such as hybrid electric vehicles (HEVs), rely on internal combustion engines for a variety of purposes, including powering propulsion systems, hydraulic systems, and generating electricity. Occupants in a vehicle may request a specific cabin temperature for comfort. Summary of the invention

[0003] A vehicle climate control system may include a coolant subsystem configured to circulate coolant between an engine, a heat generator, and a cabin heat exchanger, and a controller. The controller may be configured to retard engine spark timing to increase heat generation in response to an air inlet temperature of the heat exchanger exceeding a threshold.

[0004] A method of controlling a vehicle climate control system includes: by a controller, circulating coolant in a coolant subsystem to heat a heater core associated with a vehicle passenger compartment; and retarding engine spark timing to increase heat generation in response to an output from an air inlet sensor disposed upstream of the heater core exceeding a threshold.

[0005] A climate control system may include a coolant subsystem that circulates coolant between an engine and a heater core; and a controller. The controller may be configured to increase an idle speed of the engine in response to an air inlet temperature of the heater core exceeding a threshold. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is an illustration of a climate control system for a vehicle.

[0007] Figure 2 is a diagram of a hybrid vehicle showing a typical powertrain and energy storage components.

[0008] Figure 3 is a schematic diagram of a heating, ventilation, and air conditioning (HVAC) system including an internal combustion engine (ICE) and a heater core.

[0009] Figure 4 is a flow chart of a heating, ventilation, and air conditioning (HVAC) climate control system based on inlet temperature.

[0010] Figure 5 is a flow chart of a climate control system where the heater core coolant flow rate and the heater core air flow rate are used to calculate the heating effectiveness of the heating, ventilation and air conditioning (HVAC) system. DETAILED DESCRIPTION

[0011] Embodiments of the present disclosure are described herein. However, it should be understood that the disclosed embodiments are merely examples, and other embodiments may take various and alternative forms. The drawings are not necessarily drawn to scale; some features may be enlarged or minimized in order to show the details of a particular component. Therefore, the specific structural details and functional details disclosed herein should not be interpreted as being restrictive, but merely as a representative basis for teaching those skilled in the art to apply the present invention in different ways. As will be understood by those of ordinary skill in the art, the various features shown and described with reference to any one of the figures may be combined with the features shown in one or more other figures to produce embodiments that are not explicitly shown or described. The combination of features shown provides representative embodiments for typical applications. However, for specific applications or implementations, various combinations and modifications of features consistent with the teachings of the present disclosure may be required.

[0012] Typically climate control coolant temperature targets are inaccurate because climate control overdrives the climate system based on the target, causing the actual exhaust air to exceed actual customer demand. In non-electrified vehicles, waste heat from the engine (e.g., an internal combustion engine (ICE)) is typically considered free due to the nature of the heat source, so this overcompensation has little effect. However, electrified vehicles typically use a heat generator that includes an electric or electric heater (e.g., a resistance wire heater, a positive temperature coefficient (PTC) heater, or a thermoelectric device) to provide cabin heating when engine heat is not available. The heat generated by the heater is typically proportional to the current passing through the heater. The use of an electric or electric heater is particularly problematic for pure EVs in which there is no ICE at all. Therefore, it is desirable to optimize the coolant temperature to warm the cabin. Doing so may result in reduced fuel usage for hybrid vehicles and increased electric range for EVs (or PHEVs operating in EV mode). In this application, the term heater core will be used to describe the cabin heat exchanger. Typically, a cabin heat exchanger can be used to heat or cool the cabin.

[0013] Here, the heater core air flow rate, heater core air inlet temperature, and HVAC exhaust air temperature targets are used to calculate a target heater core coolant inlet temperature for a given selection of heater core coolant flow rate. The system controlling the heat source (such as a powertrain controller in the case of an internal combustion engine) will select the heater core coolant flow rate based on performance considerations such as noise, vibration, and harshness (NVH), pump capacity, etc. Figure 1As shown, the heater core coolant flow rate (not shown), the heater core air flow rate 4, the heater core air inlet temperature 6, and the exhaust air temperature target 8 are input to the heater coolant inlet temperature target calculator 2. This target (i.e., the output from box 2 and the input to box 10) will be input to the heater core coolant inlet temperature target box 10, which will be combined with negative feedback from the heat source controller 14 (in box 12) to guide the output capacity of the heat source based on the heater core coolant inlet temperature 16. In addition, because the heating effectiveness is mainly driven by the heater core effectiveness, the heater core coolant flow rate and the heater core air flow rate can be used to calculate the heating effectiveness of the heating, ventilation and cooling (HVAC) system. After the effectiveness has been calculated, calculating the coolant temperature target is a direct calculation based on the effectiveness definition.

[0014] Here, a climate control system for a vehicle is disclosed that controls vehicle systems including non-climate control systems (e.g., powertrain systems) based on a desired cabin temperature. To achieve the desired cabin temperature, the climate control system adjusts the vehicle systems based on a comparison of the output from an air inlet sensor and whether the difference (e.g., between an air temperature target and a coolant inlet temperature of a heater core) divided by a thermal efficiency (e.g., as the difference between an air flow rate and a coolant flow rate) drops below the coolant inlet temperature. The controller can then retard the engine spark timing to increase the amount of heat generated. In other words, the thermal efficiency parameter is the ratio of the actual heat transfer rate of a heat exchanger (e.g., a heater core) to the maximum heat transfer rate that the heat exchanger can produce.

[0015] The operation of an internal combustion engine (ICE) (e.g., a four-stroke ICE) includes drawing a fuel / air mixture into the cylinder by creating a low pressure as the piston moves away from the cylinder head and spark plug. When the piston is farthest from the cylinder head (i.e., at the bottom), the valve is closed so that the piston moves toward the cylinder head and the fuel / air mixture is compressed. Initially, when the cylinder reaches the top (i.e., closest to the head and spark plug), an electrical pulse is applied to the spark plug to create a spark at the spark plug gap. However, as the speed of the ICE increases, the timing of the spark can be advanced. Timing advance refers to igniting the spark before top dead center (BTDC) so that the spark is generated to ignite the air-fuel mixture in the combustion chamber during the compression stroke. In contrast, retarded timing can be defined as changing the timing so that the occurrence of fuel ignition is later than the manufacturer's specified time at the speed. For example, if the engine manufacturer specifies the speed to set the ignition timing at 12 degrees of BTDC, then if the ignition is adjusted to 11 degrees of BTDC, the time is called retarded. Timing advance compensates for the combustion time of the air-fuel mixture. Ignition of the mixture before the piston reaches top dead center (TDC) allows the mixture to reach complete combustion after the piston reaches TDC. When the air-fuel mixture is ignited at the correct time, maximum pressure in the cylinder occurs some time after the piston reaches TDC, allowing the ignited mixture to push the piston down the cylinder with maximum force. When the spark is retarded relative to the piston position, maximum cylinder pressure occurs after the piston has traveled down the cylinder, resulting in loss of power (i.e. horsepower) and overheating. Here, the spark is retarded to increase heat generation at the expense of producing less propulsive force.

[0016] Figure 2 A vehicle is depicted and in particular an electrified vehicle 112 which may be referred to as a plug-in hybrid electric vehicle (PHEV). Figure 2112, but the concepts are also applicable to conventional vehicles because the elements of conventional vehicles are a subset of the components shown in EV 112. Although EV is used for reference, here the plug-in hybrid electric vehicle 112 may include one or more motors 114 mechanically coupled to a hybrid transmission 116. The motor 114 may be capable of operating as a motor or a generator. In addition, the hybrid transmission 116 is mechanically coupled to the engine 118. The hybrid transmission 116 is also mechanically coupled to a drive shaft 120, which is mechanically coupled to wheels 122. When the engine 118 is turned on or off, the motor 114 can provide propulsion and deceleration capabilities. The motor 114 can also be used as a generator and provide fuel economy benefits by recovering energy that is usually lost as heat in the friction braking system. The motor 114 can also reduce vehicle emissions by allowing the engine 118 to operate at a more efficient speed and allowing the hybrid electric vehicle 112 to operate in an electric mode in which the engine 118 is turned off under certain conditions. The electrified vehicle 112 may also be a battery electric vehicle (BEV). In a BEV configuration, the engine 118 may not exist. In other configurations, the electrified vehicle 112 may be a full hybrid electric vehicle (FHEV) without plug-in capability.

[0017] The traction battery or battery pack 124 stores energy that can be used by the motor 114. The vehicle battery pack 124 can provide a high voltage direct current (DC) output. The traction battery 124 can be electrically coupled to one or more power electronic modules 126. One or more contactors 142 isolate the traction battery 124 from other components when open and connect the traction battery 124 to other components when closed. The power electronic module 126 is also electrically coupled to the motor 114 and provides the ability to transfer energy bidirectionally between the traction battery 124 and the motor 114. For example, the traction battery 124 can provide a DC voltage, while the motor 114 may operate with three-phase alternating current (AC) to function. The power electronic module 126 can convert the DC voltage into a three-phase AC current to operate the motor 114. In the regeneration mode, the power electronic module 126 can convert the three-phase AC current from the motor 114 acting as a generator into a DC voltage compatible with the traction battery 124.

[0018] The vehicle 112 may include a variable voltage converter (VVC) 152 electrically coupled between the traction battery 124 and the power electronics module 126. The VVC 152 may be a DC / DC boost converter configured to increase or boost the voltage provided by the traction battery 124. By increasing the voltage, current requirements may be reduced, resulting in a reduction in wiring size of the power electronics module 126 and the motor 114. Additionally, the motor 114 may operate with better efficiency and lower losses.

[0019] In addition to providing energy for propulsion, the traction battery 124 can also provide energy for other vehicle electrical systems. The vehicle 112 may include a DC / DC converter module 128 that converts the high-voltage DC output of the traction battery 124 into a low-voltage DC power source compatible with the low-voltage vehicle load. The output of the DC / DC converter module 128 may be electrically coupled to an auxiliary battery 130 (e.g., a 12V battery) for charging the auxiliary battery 130. The low-voltage system may be electrically coupled to the auxiliary battery 130. One or more electrical loads 146 may be coupled to the high-voltage bus. The electrical load 146 may have an associated controller that operates and controls the electrical load 146 when appropriate. Examples of the electrical load 146 may be a fan, an electric heating element, and / or an air conditioning compressor.

[0020] The electrified vehicle 112 may be configured to recharge the traction battery 124 from an external power source 136. The external power source 136 may be a connection to an electrical outlet. The external power source 136 may be electrically coupled to a charger or electric vehicle supply equipment (EVSE) 138. The external power source 136 may be a distribution network or grid provided by an electric utility company. The EVSE 138 may provide circuits and controls for regulating and managing energy transfer between the power source 136 and the vehicle 112. The external power source 136 may provide DC or AC power to the EVSE 138. The EVSE 138 may have a charging connector 140 for plugging into a charging port 134 of the vehicle 112. The charging port 134 may be any type of port configured to transfer power from the EVSE 138 to the vehicle 112. The charging port 134 may be electrically coupled to a charger or an onboard power conversion module 132. The power conversion module 132 may regulate the power supplied from the EVSE 138 to provide the appropriate voltage and current levels to the traction battery 124. The power conversion module 132 may interface with the EVSE 138 to coordinate power delivery to the vehicle 112. The EVSE connector 140 may have pins that mate with corresponding recesses of the charging port 134. Alternatively, the various components described as being electrically coupled or connected may transfer power using wireless inductive coupling.

[0021] One or more wheel brakes 144 may be provided for decelerating the vehicle 112 and preventing the movement of the vehicle 112. The wheel brakes 144 may be hydraulically actuated, electrically actuated, or some combination thereof. The wheel brakes 144 may be part of a braking system 150. The braking system 150 may include other components for operating the wheel brakes 144. For simplicity, the drawings depict a single connection between the braking system 150 and one of the wheel brakes 144. Connections between the braking system 150 and other wheel brakes 144 are implied. The braking system 150 may include a controller for monitoring and coordinating the braking system 150. The braking system 150 may monitor the braking components and control the wheel brakes 144 for vehicle deceleration. The braking system 150 may respond to driver commands and may also operate autonomously to implement features such as stability control. The controller of the braking system 150 may implement a method for applying the requested braking force when requested by another controller or sub-function.

[0022] The electronic modules in the vehicle 112 can communicate via one or more vehicle networks. The vehicle network can include multiple channels for communication. One channel of the vehicle network can be a serial bus, such as a controller area network (CAN). One channel of the vehicle network can include Ethernet as defined by the Institute of Electrical and Electronics Engineers (IEEE) 802 series of standards. Additional channels of the vehicle network can include discrete connections between modules and can include power signals from the auxiliary battery 130. Different signals can be transmitted via different channels of the vehicle network. For example, a video signal can be transmitted via a high-speed channel (e.g., Ethernet), while a control signal can be transmitted via CAN or discrete signals. The vehicle network can include any hardware and software components that facilitate the transmission of signals and data between modules. The vehicle network is not described in detail in the accompanying drawings. Figure 2 1, but it may be implied that the vehicle network may be connected to any electronic module present in the vehicle 112. A vehicle system controller (VSC) 148 may be present to coordinate the operation of the various components.

[0023] Typically, the VVC 152 is configured as a boost converter. The VVC 152 may include input terminals that may be coupled to terminals of the traction battery 124 via contactors 142. The VVC 152 may include output terminals that are coupled to terminals of the power electronics module 126. The VVC 152 may be operated such that a voltage at the output terminals is greater than a voltage at the input terminals. The vehicle 112 may include a VVC controller that detects and controls electrical parameters (e.g., voltage and current) at various locations within the VVC 152. In some configurations, the VVC controller may be included as part of the VVC 152. The VVC controller may determine an output reference voltage, The VVC controller can be based on electrical parameters and reference voltage The VVC 152 may be controlled by a VVC controller to determine a control signal sufficient to cause the VVC 152 to reach a desired output voltage. In some configurations, the control signal may be implemented as a pulse width modulated (PWM) signal, wherein the duty cycle of the PWM signal varies. The control signal may be operated at a predetermined switching frequency. The VVC controller may use the control signal to command the VVC 152 to provide a desired output voltage. The specific control signal that operates the VVC 152 may be directly related to the amount of boost provided by the VVC 152.

[0024] refer to Figure 2 , the VVC 152 can increase or "step up" the voltage potential of the power provided by the traction battery 124. The traction battery 124 can provide high voltage (HV) DC power. In some configurations, the traction battery 124 can provide a voltage between 150 volts and 400 volts. The contactor 142 can be electrically coupled in series between the traction battery 124 and the VVC 152. When the contactor 142 is closed, the HV DC power can be transferred from the traction battery 124 to the VVC 152. The input capacitor can be electrically coupled in parallel with the traction battery 124. The input capacitor can reduce any voltage and current ripple. The VVC 152 can receive the HV Dc power and increase or "step up" the voltage potential of the input voltage according to the duty cycle. Typically, the output capacitor is electrically coupled between the output terminals of the VVC 152 for the input terminals of the power electronics module 126 to stabilize the bus voltage and reduce the voltage and current ripple at the output terminals of the VVC 152.

[0025] Figure 3300, also referred to as a coolant subsystem. The engine 302 generates heat as a waste product of combustion when it is operating. To cool the engine 302, coolant is circulated through the engine 302 through a coolant inlet port 324 and a coolant outlet port 326. The outlet 304 separates the heated coolant to flow to the radiator 310, the thermostat 312, the degassing bottle 316, and the HVAC electric pump 326. The thermostat 312 controls the flow of coolant to the main electric pump 314, so that if the temperature of the coolant is below a threshold, the thermostat 312 directs the coolant from the outlet 304 to the electric pump 314, thereby bypassing the radiator 310. If the temperature of the coolant is above a threshold, the thermostat 312 directs the coolant through the radiator 310 to the electric pump. In some embodiments, if the temperature of the coolant exceeds a high threshold, the electric fan 308 is activated to help air flow through the radiator, thereby cooling the coolant. The coolant flowing from the outlet 304 to the HVAC electric pump 326 can flow through a heat generator 318 (such as an electric heater). The heat generator 318 may include a resistance wire heater, a positive temperature coefficient (PTC) heater, a heat pump or other electric heat source. The coolant flow rate and temperature are measured by a sensor 330, after which the coolant is transferred to the heater core 320 and reaches the downstream valve 322 (also referred to as the heater core isolation valve). The downstream valve 322 is also referred to as the heater core isolation valve (HCIV). The heater core 320 is typically located in the passenger compartment within the passenger compartment HVAC subsystem 338, which includes an electric fan 328, an evaporator 334, a condenser / compressor 332, an air filter 340, and a passenger compartment filter 336. The air inlet draws air through the air filter 340 at the inlet air temperature and leaves after passing through the heater core 320 or the evaporator 334. The desired air temperature is the exhaust air temperature, which is controlled to be at the exhaust air temperature target in order to change the cabin temperature based on the HVAC controller. The electric heater 318 can increase the temperature of the coolant to provide a hotter coolant to the heater core 320 so that the desired output temperature of the passenger compartment HVAC subsystem 338 can meet the requirements for obtaining the desired temperature in the passenger compartment. In addition to generating heat, the heat generator 318 can also be used to remove heat (e.g., cooling) through a vapor compression heat pump or a thermoelectric heat pump. In another embodiment, the condenser / compressor 332 and the evaporator 334 are removed, and their functions are performed by the heat generator 318 and the heater core 320. Based on the heater core isolation valve position, the flow will be valve 322 to the electric pump 326 or valve 322 to the thermostat 312.

[0026] Figure 4 A flow chart 400 of a heating, ventilation, and air conditioning (HVAC) climate control system based on inlet temperature.

[0027] Here, the heater core air flow rate (e.g., based on the speed of the fan 328, and the ventilation operating mode such as recirculation, defrost, floor heating, etc.), the heater core air inlet temperature (e.g., based on the temperature of the air flowing through the evaporator 334), and the HVAC exhaust air temperature target (e.g., an estimated temperature to raise the cabin temperature to the desired temperature) are used to calculate a target heater core coolant inlet temperature (e.g., the estimated temperature at sensor 330) for a given heater core coolant flow rate. A system controlling the heat source (such as a powertrain controller in the case of an internal combustion engine or a PTC controller for a PTC heater) can operate the heater core subsystem to achieve the coolant flow rate based on performance considerations such as engine cooling, pump energy usage, noise, vibration, and harshness (NVH). As Figure 4 As shown, the heater core coolant inlet temperature target calculator 402 receives inputs indicating multiple parameters from multiple sources, including HVAC air flow rate 404, heater core air inlet temperature 406, and exhaust air temperature target 408. The target calculator 402 outputs a signal to drive the HVAC subsystem to the heater core coolant inlet temperature target in box 410. Then, in box 412, the target is compared with the actual heater core coolant inlet temperature 416 through signal feedback to guide the output capacity of the heat source. The heat source controller 414 includes a powertrain controller and an electric heat controller. The powertrain controller can increase the idle speed of the engine to increase heat generation, and if operating and providing propulsion, the powertrain controller can increase fuel flow and retard engine spark timing to increase heat generation while maintaining the requested mechanical horsepower output from the engine (e.g., engine 302). In addition, current can be applied to an electric heater (e.g., electric heater 318) to increase the temperature of the coolant before circulating to the heater core (e.g., heater core 320).

[0028] Figure 55 is a climate control system flow chart 500, wherein at least a heater core coolant flow rate 504 and an HVAC air flow rate 512 are used to calculate an HVAC heating effectiveness 514. The heater core coolant flow 504 may be based on output from a coolant flow rate sensor, or it may be based on characteristics such as coolant temperature, pump speed, or coolant pressure. The HVAC air flow rate 512 may be based on output from an air flow rate sensor, or it may be based on characteristics such as ambient temperature, fan speed, atmospheric pressure, or HVAC operating mode. HVAC operating modes include exhaust flow paths such as defrost, floor, front exhaust, recirculation, and bypass. Thus, the air flow rate may be determined by calibration according to the HVAC operating mode. In one embodiment, the HVAC heating effectiveness 514 is calculated dynamically, and in another embodiment, the HVAC heating effectiveness 514 is calculated offline and stored in a lookup table for quick access. In yet another embodiment, the HVAC heating effectiveness 514 is partially calculated offline and stored as a matrix so that multiple variables are used to calculate the effectiveness. And in another embodiment, the HVAC heating effectiveness 514 uses a closed-form correlation with an adjustable coefficient to determine the effectiveness. The output of the HVAC heating effectiveness 514 is forwarded to the temperature target calculator 502, which calculates a heater core coolant inlet temperature target based on inputs including the effectiveness from box 514, the HVAC exhaust air temperature target box 508, and the heater core air inlet temperature box 506. Here, the HVAC exhaust air temperature target box 508 can be based on calculated data (such as the desired cabin temperature and the current cabin temperature), and the heater core air inlet temperature box 506 can be the output from a temperature sensor or can be based on other data (such as ambient temperature, fan speed, or HVAC operating mode). In one embodiment, the heater core coolant inlet temperature target is proportional to the inverse of the HVAC effectiveness (e.g., from the HVAC effectiveness calculator 514) multiplied by the difference between the HVAC exhaust air temperature target and the heater core air inlet temperature. The product of the inverse and the difference is then added to the heater core air inlet temperature, resulting in the heater core coolant inlet temperature target. Then, proceed to the heater core coolant inlet temperature target box 510, which is Figure 4 Used to operate the powertrain and electric heater.

[0029] Figure 5 Details of the target calculation are provided. Specifically, it is shown that the heater core coolant flow rate and the heater core air flow rate are used to determine the heating effectiveness of the HVAC, which is primarily driven by the heater core effectiveness. With the knowledge or effectiveness, the controller can determine the coolant temperature target based on the definition of effectiveness. It should be noted that the form of the equation presented here assumes that the minimum heat transfer fluid capacity is always on the air side, but this equation can also be used in other situations.

[0030] The above-described climate control system can help reduce the energy cost of providing heat by supplementing the heat provided by the engine or vehicle power source. More specifically, the HVAC subsystem can generate additional heat and provide additional heat to the coolant, which can be used to heat the passenger compartment of the vehicle. In addition, the climate control system can help to commonize climate control system components, such as heater core and / or ventilation system design. In this way, a common heater core and / or ventilation system can be provided with vehicles having different powertrain configurations, such as models having internal combustion engine and hybrid electric powertrain options.

[0031] The control logic or function executed by the controller can be represented by a flowchart or similar diagram in one or more figures. These figures provide representative control strategies and / or logic that can be implemented using one or more processing strategies (such as event-driven, interrupt-driven, multi-tasking, multi-threading, etc.). Therefore, the various steps and / or functions shown may be executed in the order shown, executed in parallel, or omitted in some cases. Although not always explicitly shown, it will be recognized by those of ordinary skill in the art that one or more of the steps or functions shown can be repeated depending on the specific processing strategy used. Similarly, the processing sequence is not necessarily required to achieve the features and advantages described herein, but is provided for ease of illustration and description. The control logic can be implemented primarily in software executed by a microprocessor-based vehicle, engine and / or powertrain controller (such as a controller). Of course, depending on the specific application, the control logic can be implemented in one or more controllers in software, hardware, or a combination of software and hardware. When implemented in software, the control logic can be provided in one or more computer-readable storage devices or media, which have storage data representing codes or instructions executed by a computer to control a vehicle or its subsystems. A computer-readable storage device or medium may include one or more of a number of known physical devices that utilize electrical, magnetic, and / or optical storage to maintain executable instructions and associated calibration information, operating variables, and the like.

[0032] The process, method or algorithm disclosed herein can be delivered / implemented by a processing device, a controller or a computer, which can include any existing programmable electronic control unit or a dedicated electronic control unit. Similarly, the process, method or algorithm can be stored as data and instructions that can be executed by a controller or a computer in many forms, including but not limited to information permanently stored on a non-writable storage medium (such as a read-only memory (ROM) device), and information that can be stored on a writable storage medium (such as a floppy disk, a tape, a compact disk (CD), a random access memory (RAM) device and other magnetic and optical media). The process, method or algorithm can also be implemented in a software executable object. Alternatively, the process, method or algorithm can be embodied in whole or in part using suitable hardware components, such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a state machine, a controller or other hardware component or device, or a combination of hardware, software and firmware components.

[0033] Although exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms covered by the claims. The words used in the specification are descriptive rather than restrictive, and it should be understood that various changes can be made without departing from the spirit and scope of the present disclosure. As previously mentioned, the features of the various embodiments can be combined to form other embodiments of the present invention that may not be explicitly described or illustrated. Although various embodiments can be described as providing advantages or being superior to other embodiments or prior art implementations relative to one or more desired characteristics, those of ordinary skill in the art recognize that one or more features or characteristics can be compromised to achieve the desired overall system properties, depending on the specific application and implementation. These properties may include, but are not limited to, cost, strength, durability, life cycle cost, marketability, appearance, packaging, size, maintainability, weight, manufacturability, ease of assembly, etc. Therefore, embodiments described as being less desirable than other embodiments or prior art implementations relative to one or more characteristics are not outside the scope of the present disclosure and may be desirable for specific applications.

[0034] According to the present invention, a vehicle climate control system is provided, which has: a coolant subsystem, which is configured to circulate coolant between an engine, a heat generator and a cabin heat exchanger; and a controller, which is configured to retard engine spark timing to increase heat generation in response to an air inlet temperature of the heat exchanger exceeding a threshold.

[0035] According to one embodiment, the controller is further configured to increase the idle speed of the engine in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature falling below the air inlet temperature.

[0036] According to one embodiment, the threshold value is defined by a quotient of (i) a difference between an exhaust temperature target and the air inlet temperature and (ii) a thermal efficiency parameter.

[0037] According to one embodiment, the thermal efficiency parameter is based on air flow rate and coolant flow rate.

[0038] According to one embodiment, the coolant flow rate is based on the configuration of the coolant subsystem, including thermostat position, heater core isolation valve position, main pump speed, and HVAC pump speed.

[0039] According to one embodiment, wherein the coolant flow rate is based on an output from a flow meter.

[0040] According to one embodiment, the heat generator is an electric heater and the controller is further configured to reduce current to the electric heater in response to a parameter proportional to the difference between an exhaust temperature target and the air inlet temperature exceeding the air inlet temperature.

[0041] According to one embodiment, the electric heater is a resistive heater or a positive temperature coefficient (PTC) heater.

[0042] According to one embodiment, the heat generator is a thermoelectric heat pump or a vapor compression heat pump configured to provide cabin heating or cooling, and the controller is further configured to switch the heat generator from a heating mode to a cooling mode in response to a parameter proportional to the difference between a discharge temperature target and the air inlet temperature exceeding the air inlet temperature.

[0043] According to one embodiment, a method of controlling a vehicle climate control system is provided, comprising: by a controller, circulating coolant in a coolant subsystem to heat a heater core associated with a vehicle passenger compartment; and retarding engine spark timing to increase heat generation in response to an output from an air inlet sensor disposed upstream of the heater core exceeding a threshold.

[0044] According to one embodiment, the invention is further characterized by the controller increasing the idle speed of the engine in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature falling below the air inlet temperature.

[0045] According to one embodiment, the threshold value is defined by a quotient of a difference between an exhaust temperature target and the air inlet temperature and a thermal efficiency parameter based on an air flow rate and a coolant flow rate.

[0046] According to one embodiment, the invention is further characterized by reducing current to the electric heater in response to a parameter proportional to the difference between a discharge temperature target and said air inlet temperature exceeding said air inlet temperature.

[0047] According to one embodiment, the electric heater is a resistive heater or a positive temperature coefficient (PTC) heater.

[0048] According to one embodiment, the present invention is further characterized in that the controller switches the heat generator from a heating mode to a cooling mode in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature exceeding the air inlet temperature, wherein the heat generator is a thermoelectric heat pump or a vapor compression heat pump.

[0049] According to the present invention, a climate control system is provided having a coolant subsystem that circulates coolant between an engine and a heater core; and a controller configured to increase an idle speed of the engine in response to an air inlet temperature of the heater core exceeding a threshold.

[0050] According to one embodiment, the controller is further configured to increase the idle speed of the engine in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature falling below the air inlet temperature.

[0051] According to one embodiment, the threshold value is defined by a quotient of a difference between an exhaust temperature target and the air inlet temperature and a thermal efficiency parameter based on an air flow rate and a coolant flow rate.

[0052] According to one embodiment, the coolant subsystem also includes an electric heater, and the controller is further configured to reduce current to the electric heater in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature exceeding the air inlet temperature, wherein the electric heater is a resistive heater or a positive temperature coefficient (PTC) heater.

[0053] According to one embodiment, the coolant subsystem further includes a heat generator that is a thermoelectric heat pump or a vapor compression heat pump configured to provide cabin heating or cooling, and the controller is further configured to switch the heat generator from a heating mode to a cooling mode in response to a parameter proportional to the difference between the exhaust temperature target and the air inlet temperature exceeding the air inlet temperature.

Claims

1. A vehicle climate control system, which comprises: a coolant subsystem configured to circulate coolant between an engine, a heat generator, and a passenger compartment heat exchanger; and a controller configured to delay engine spark timing to increase heat generation in response to an air inlet temperature of the heat exchanger exceeding a threshold, wherein the threshold is defined by a quotient of a difference between an exhaust temperature target and the air inlet temperature and a heat efficiency parameter, and wherein the heat efficiency parameter is based on a difference between an air flow rate and a coolant flow rate.

2. The vehicle climate control system according to claim 1, wherein the controller is further configured to increase an idle speed of the engine in response to a parameter proportional to a difference between the exhaust temperature target and the air inlet temperature dropping below the air inlet temperature.

3. The vehicle climate control system according to claim 1, wherein the coolant flow rate is based on a configuration of the coolant subsystem, including a thermostat position, a heater core isolation valve position, a main pump speed, and an HVAC pump speed.

4. The vehicle climate control system according to claim 1, wherein the coolant flow rate is based on an output from a flow meter.

5. The vehicle climate control system according to claim 1, wherein the heat generator is an electric heater, and the controller is further configured to reduce a current supplied to the electric heater in response to a parameter proportional to a difference between the exhaust temperature target and the air inlet temperature exceeding the air inlet temperature.

6. The vehicle climate control system according to claim 5, wherein the electric heater is a resistance heater or a positive temperature coefficient heater.

7. The vehicle climate control system according to claim 1, wherein the heat generator is a thermoelectric heat pump or a vapor compression heat pump configured to provide heating or cooling for the passenger compartment, and the controller is further configured to switch the heat generator from a heating mode to a cooling mode in response to a parameter proportional to a difference between the exhaust temperature target and the air inlet temperature exceeding the air inlet temperature.

8. A method for controlling a vehicle climate control system, which comprises: circulating, by a controller, coolant in a coolant subsystem to heat a heater core associated with a vehicle passenger compartment, and delaying engine spark timing to increase heat generation in response to an output from an air inlet temperature sensor disposed upstream of the heater core exceeding a threshold, wherein the threshold is defined by a quotient of a difference between an exhaust temperature target and an output of the air inlet temperature sensor and a heat efficiency parameter, and wherein the heat efficiency parameter is based on a difference between an air flow rate and a coolant flow rate.

9. The method according to claim 8, further comprising increasing, by the controller, an idle speed of the engine in response to a parameter proportional to a difference between the exhaust temperature target and an output of the air inlet temperature sensor dropping below the output.

10. The method according to claim 8, further comprising reducing the current supplied to the electric heater in the coolant subsystem in response to a parameter proportional to the difference between the discharge temperature target and the output of the air inlet temperature sensor exceeding the output.

11. The method according to claim 10, wherein the electric heater is a resistance heater or a positive temperature coefficient heater.

12. The method according to claim 8, further comprising, by the controller, switching the heat generator in the coolant subsystem from a heating mode to a cooling mode in response to a parameter proportional to the difference between the discharge temperature target and the output of the air inlet temperature sensor exceeding the output of the air inlet temperature sensor, wherein the heat generator is a thermoelectric heat pump or a vapor compression heat pump.

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