Method for valve position detection for heater core insulation for a vehicle

Abstract

Method for detecting the position of a valve (44) of a vehicle (10), comprising an engine (40), a heat exchanger configured to heat a passenger compartment of the vehicle (10), an electric heater (42) configured to heat a coolant for the heat exchanger, and a valve system with the valve (44) configured to selectively direct the coolant from the engine (40) to the heat exchanger, and a controller configured to perform the following process steps: - Measuring the temperature of the coolant entering the heat exchanger, - Measuring the temperature of the coolant exiting the engine (40), - Detecting the position of the valve (44) based on the temperature of the coolant entering the heat exchanger and the temperature of the coolant exiting the engine (40).

Description

CROSS-REFERENCE TO RELATED REGISTRATION

[0001] This application claims the benefit of preliminary US application No. 61 / 716,077, filed on October 19, 2012, the disclosure of which is incorporated herein by reference in its entirety. GENERAL STATE OF THE ART Background

[0002] To provide passenger comfort, vehicles have the ability to heat or cool the passenger compartment. Conventional vehicles use waste heat from the engine as the sole heating source for the passenger compartment. With the introduction of battery electric vehicles (BEVs), waste heat is no longer available, so other means of heating the passenger compartment are required. A typical BEV may use an electric heater to warm the passenger compartment. Similarly, hybrid electric vehicles (HEVs) have various problems, as the engine does not always need to be running and generating waste heat for use by the heating system. Plug-in hybrid electric vehicles (PHEVs) exacerbate this problem, as they operate with the engine off for significant periods.To achieve optimal fuel economy, it is desirable to heat the passenger compartment without relying solely on engine waste heat. Heating systems for motor vehicles are disclosed in DE 10 2009 020 468 A1 and US 2001 / 0018832 A1.

[0003] In a heating system, valves may be present to change the coolant flow through the system. These valves can be moved to a desired position via a controller. During normal operation, the valve is indeed in the actuated position set by the controller. During malfunctions, the valve may be in a position that does not correspond to the position selected by the controller. It is desirable to detect these situations to ensure that the system operates in a manner consistent with the actual valve position. SUMMARY

[0004] According to the invention, a method according to claim 1 is provided. Advantageous embodiments are described in the dependent claims. In an illustrative embodiment, the method for detecting the position of a valve in a hybrid vehicle comprises an engine, an electric heater, a heat exchanger, and a valve system with a valve arranged to direct coolant from the engine to the electric heater. The illustrative system also includes a controller configured to perform the following method steps: measuring the temperature of the coolant entering the heat exchanger, measuring the temperature of the coolant exiting the engine, and detecting the position of the valve based on the temperature of the coolant entering the heat exchanger and the temperature of the coolant exiting the engine.The illustrative method can exhibit the ability to operate a heater loop independently of the motor-heater loop. The illustrative method can provide robust heating capability despite the failure of some system components. The illustrative method can also provide operating modes to improve the effectiveness of heating the passenger compartment. For example, the method can diagnose valve malfunctions and operate the system in a manner consistent with the valve position.

[0005] The method requires a vehicle equipped with an engine, a heat exchanger or heater core, an electric heater, and a valve system capable of selectively directing coolant from the engine to the heat exchanger. The valve system can detect the valve's position based on the temperature of the coolant entering the heat exchanger and the temperature of the coolant exiting the engine. The valve system can recognize correct valve operation when the valve is positioned to fluidically isolate the coolant exiting the engine from the heat exchanger when the temperature rise of the coolant entering the heat exchanger is greater than the temperature rise of the coolant exiting the engine, provided the electric heater is on and the engine is off.The correct valve position can be detected when the temperature rise of the coolant entering the heat exchanger is greater than a first threshold and the temperature rise of the coolant exiting the engine is less than a second threshold. The valve system can detect a faulty valve operation if the valve is actually directing coolant from the engine to the heat exchanger when it is instructed to fluidically isolate coolant from the engine and the heat exchanger. The fault position can be detected if the temperature rise over time of the coolant entering the heat exchanger is less than a first threshold or the temperature rise over time of the coolant exiting the engine is greater than a second threshold. The system can be configured to generate an output representing a valve position fault and to store a diagnostic code.

[0006] The method requires a vehicle equipped with an engine, a heat exchanger or heater core, an electric heater, and a valve system capable of selectively directing coolant from the engine to the electric heater. The valve system can detect the valve's position based on temperature changes over time of the coolant exiting the electric heater and the coolant exiting the engine. The valve system can recognize correct valve operation when the valve is positioned to fluidically isolate coolant from the electric heater when the temperature change of the coolant exiting the electric heater is greater than the temperature change of the coolant exiting the engine while the electric heater is on and the engine is off.The correct valve position can be detected when the temperature change of the coolant exiting the electric heater is greater than a first threshold and the temperature change of the coolant exiting the engine is less than a second threshold. The valve system can detect a faulty valve operation if the valve is actually directing coolant from the engine to the electric heater when it is instructed to fluidically isolate coolant from the electric heater. The fault position can be detected if the temperature change over time of the coolant exiting the electric heater is less than a first threshold or the temperature change of the coolant exiting the engine is greater than a second threshold. The system can be configured to generate an output representing a valve position fault and store a diagnostic code.

[0007] The method can include the steps of activating a pump, instructing the valve to direct coolant through a heat source and fluidically isolating the heat source from the engine, activating the heat source, and, in response, outputting a signal indicating the valve's position based on a change in coolant temperature associated with the heat source and a change in coolant temperature associated with the engine when the engine is off. The engine may be off for a predetermined period before the position is detected. The valve position can be detected as being in the disturbed position, where the valve directs coolant from the engine to the heat source, if the temperature change of the coolant associated with the heat source is less than a first threshold or if the temperature change of the coolant associated with the engine is greater than a second threshold.When a faulty position is detected, an output representing the fault can be generated. The valve position can be recognized as being in a correct position, where the valve is not directing coolant from the engine to the heat source, if the temperature change of the coolant supplied to the heat source is greater than a first threshold and the temperature change of the coolant supplied to the engine is less than a second threshold. Valve position detection can be performed when an electrical valve fault is detected. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a schematic representation of a vehicle. Fig. Figure 2 is a schematic representation of vehicle components that implement a climate control strategy. Fig. Figure 3 is a flowchart of a valve position diagnosis. DETAILED DESCRIPTION

[0008] Detailed embodiments of the present invention are disclosed herein as required; however, it is understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of certain components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching the person skilled in the art to use the present invention in various ways.

[0009] Vehicles can have two or more propulsion devices, such as a primary and secondary propulsion device. For example, the vehicle can have a combustion engine and an electric motor, a fuel cell and an electric motor, or other combinations of propulsion devices known in engineering. The engine can be a compression or spark-ignition internal combustion engine, or an external combustion engine, and the use of different fuels is taken into account. In one example, the vehicle is a hybrid electric vehicle (HEV) and may additionally have the capability to be connected to an external power grid, as in a plug-in hybrid electric vehicle (PHEV).The PHEV structure is used in the figures and to describe the various embodiments below; however, it is taken into account that the various embodiments may be used with vehicles with other drive devices or combinations of drive devices as are known in the art.

[0010] A plug-in hybrid electric vehicle (PHEV) incorporates an extension of existing hybrid electric vehicle (HEV) technology, in which an electric battery supplements an internal combustion engine and at least one electric motor to achieve further increased mileage and reduced vehicle emissions. A PHEV utilizes a larger-capacity battery than a standard hybrid vehicle and also has the capability to recharge the battery from the electrical grid, such as a charging station's wall socket. This further improves overall vehicle system operating efficiency in both electric-only and combined hydrocarbon / electric driving modes.

[0011] Fig. Figure 1 represents a power transmission configuration and control system of a vehicle, in particular a hybrid electric vehicle (HEV) or plug-in hybrid electric vehicle (PHEV) 10. A split-drive hybrid electric vehicle 10 can be a parallel hybrid electric vehicle. The HEV configuration shown is for illustrative purposes only and is not intended to be limiting, as the present disclosure relates to HEVs, PHEVs, or other vehicle types with any suitable architecture. In this power transmission configuration, there are two power sources 12, 14 connected to the drivetrain, which are a combination of motor and generator subsystems utilizing a planetary gear set for their connection to each other, and which include the electric drive system (motor, generator, and battery subsystems). The battery subsystem is an energy storage system for the generator and the motor.The charging generator speed varies the motor output power distribution between an electrical path and a mechanical path. In a vehicle 10 with a power-sharing power transmission system, unlike in conventional vehicles, the motor 16 requires either the generator torque resulting from the motor speed control or the generator braking torque to transmit its output power to the drive for forward motion via both the electrical and mechanical paths (distribution modes) or via only the mechanical path (parallel mode). When operating using the second power source 14, the electric motor 20 draws energy from the battery 26 and provides drive for forward and reverse movements independently of the motor 16. This operating mode is called "electric drive" or all-electric mode or EV mode.

[0012] Unlike conventional power transmission systems, this power-sharing power transmission system integrates the two power sources 12, 14 for seamless cooperation to meet the driver's requirements without exceeding system limits (such as battery limits), while optimizing overall power transmission system efficiency and performance. Coordination control between the two power sources is required. As in Fig. As shown in Figure 1, there is a hierarchical vehicle system controller (VSC) 28 that performs the coordination control in this power-sharing power transmission system. Under normal power transmission conditions (no subsystems / components malfunctioning), the vehicle system controller (VSC) interprets the driver's requests (e.g., PRND and acceleration or deceleration requests) and then determines the wheel torque command based on the driver request and the power transmission limits. Furthermore, the vehicle system controller (VSC) 28 determines when and how much torque each power source must provide to meet the driver's torque request and achieve the engine's operating point (torque and speed).

[0013] In the configuration of a PHEV vehicle 10 (shown in through view), the battery 26 can also be charged using a socket 32 ​​which is connected to the mains or another external power source and coupled to the battery 26, possibly via a battery charger / converter 30.

[0014] The vehicle 10 can be operated in electric mode (EV), with the battery 26 supplying all the energy needed to power the electric motor 20. In addition to fuel savings, operating in EV mode can improve driving comfort through reduced noise and enhanced drivability, for example, through smoother electric operation, less noise, vibration, and harshness (NVH), and faster response. Furthermore, operating in EV mode has a positive environmental impact, as the vehicle produces zero emissions during this mode.

[0015] A plug-in hybrid electric vehicle (PHEV) shares characteristics with both an internal combustion engine (ICE) and a battery electric vehicle (BEV). A PHEV can have a certain driving range in which propulsion is provided solely by an electric motor 20, which is powered by a battery 26. Once the charge of the battery 26 is depleted to a certain degree, the motor 16 can be started. The motor 16 can provide power to drive the vehicle and to recharge the battery 26. In all-electric mode, the motor 16 does not run. Since the motor 16 is not running, no engine heat is generated that can be used to heat the passenger compartment. A PHEV can start the motor 16 in response to a need to heat the passenger compartment. However, this disrupts all-electric operation and can affect fuel economy and emissions.

[0016] A PHEV can operate in different modes. In one mode, the PHEV can operate in a charge maintenance mode. A charge maintenance mode is a mode in which the charge level of the battery 26 is maintained within a certain range. This can be achieved by operating the engine 16 to supply the generator 18 with power to recharge the battery 26. In another mode, the PHEV can operate in a charge-consuming mode. A charge-consuming mode is a mode in which the battery 26 is allowed to discharge to a lower degree. This can occur in all-electric mode when the vehicle's drive is powered by the electric motor 20 using electricity from the battery 26.

[0017] One possible system for providing passenger compartment heating for a PHEV is in Fig. 2 shown. The system provides two coolant heat sources. The system can use heat from the engine 40 to heat the coolant, as in a conventional ICE vehicle. The system can also provide heat via an electric heater 42, as in a BEV system. Having multiple heat sources allows for flexibility during normal operating conditions and some redundancy during failure modes. The system allows the coolant from the different heat sources to flow through the heater core. The addition of a heater core isolation valve (HCIV) 44 allows the passenger compartment heating system to select the source of heated coolant. A vehicle system controller (VSC) (28, Fig. 1) can control the operation of the system. The Vehicle System Control (VSC) (28, Fig. 1) can determine the heating mode based on the passenger compartment heating demand and the status of the various components in the heating system. To ensure robust operation, the Vehicle System Control (VSC) (28, Fig. 1) Try to work with missing or malfunctioning controls by selecting a suitable operating mode.

[0018] The heater core isolation valve (HCIV) 44 can be used to activate various coolant loops. In one position, the heater core isolation valve (HCIV) 44 forms an electric heater loop 66. In this position, the coolant flows in a loop consisting of the heater core isolation valve (HCIV) 44, the auxiliary water pump 46, the electric heater 42, and the heater core 50, without being limited to this specific order. In another position, the heater core isolation valve (HCIV) 44 forms a combined heating loop 68 that passes through the motor 40. In the combined heating loop, coolant flows through the heater core isolation valve (HCIV) 44, the motor 40, the water pump 54, the thermostat 58, the auxiliary water pump 46, the electric heater 42, and the heater core 50, without being limited to this specific order.There is also a separate engine loop in which coolant flows through the engine 40, the water pump 54, the thermostat 58, and the radiator 56, although this does not necessarily occur in that order. Depending on the operating mode, one or both of the pumps, 46 or 54, must be activated for coolant to flow in the system.

[0019] The system may also include an additional water pump 46 to force coolant to flow through the system. A temperature sensor 48 may be included to measure the temperature of the coolant entering the heater core 50. The coolant flows through a heater core 50, which allows heat to be transferred from the coolant to air entering the passenger compartment. The heat can be transferred from the coolant in the heater core 50 using a blower 52 to supply air over the heater core 50 and into the passenger compartment.

[0020] The system may also include a water pump 54 to force coolant to flow through the engine 40. The water pump 54 may be mechanically or electrically driven. In certain modes, the water pump 54 may also force coolant through the heater core 50. The system may also include a radiator 56 to dissipate heat from the coolant. The system may also include a thermostat 58 to control the coolant flow between the radiator 56 and the engine 40. The system may also include a degassing cylinder 60, which acts as a coolant reservoir, removes air from the coolant, and provides pressure equalization. The cooling system may also include an exhaust gas recirculation (EGR) system 62, which recirculates a portion of the engine exhaust gas back to the engine cylinders.In addition, the system may include an engine coolant temperature sensor 64 for determining the temperature of the coolant exiting the engine 40, or the temperature of the engine coolant exiting the engine may be estimated or derived from other measurements.

[0021] The system has the ability to modify the coolant flow through the system in response to the desired coolant heat source. Based on the position of the heater core isolation valve (HCIV) 44, coolant can flow in different loops. Separate coolant temperatures can be achieved in each loop depending on the heating / cooling requirements of each loop at a given time. Adding the heater core isolation valve (HCIV) 44 allows the coolant flow to be modified. The heater core isolation valve (HCIV) 44 can be an electrically actuated valve that modifies the coolant flow through the system. The heater core isolation valve (HCIV) 44 can be a three-way valve, allowing one port to be alternately connected to each of the other two ports based on an activation signal.The heater core isolation valve (HCIV) 44 can allow the coolant loops to be combined into a larger coolant loop. The heater core isolation valve (HCIV) 44 can be configured to allow coolant to flow from the engine coolant loop through the heater core isolation valve (HCIV) 44 to the electric heater loop 66.

[0022] A controller can be used to activate the heater core isolation valve (HCIV) 44. Depending on the design of the heater core isolation valve (HCIV) 44, it may or may not provide feedback regarding the current position of the heater core isolation valve (HCIV) 44. It is desirable for the controller to know with some certainty that the heater core isolation valve (HCIV) 44 is in the correct position. The position of the heater core isolation valve (HCIV) 44 can be determined by observing the system's behavior during operation.

[0023] An indirect method for determining the position of the heater core isolation valve (HCIV) 44 is possible using existing feedback in the system under known operating conditions. The method can first determine whether the conditions for entering the HCIV position determination are correct. The system can initially determine whether the conditions for determining the position are suitable by evaluating the entry conditions. The entry conditions to be evaluated can be as follows: the motor 40 is not running, the motor 40 has been off for a required minimum time, the ambient temperature is above a minimum value, the speed of the blower 52 is below a threshold value, the temperature sensors are functioning correctly, the auxiliary water pump 46 is activated, the electric heater 42 is activated to heat the coolant, and the heater core isolation valve (HCIV) 44 has been activated towards the electric heater loop.Other entry criteria may include the detection of an open circuit or a short circuit to ground in the control lines of the heater core isolation valve (HCIV) 44. Depending on the specific heater core isolation valve (HCIV) 44, the diagnosis may only be performed if a circuit fault has been detected. Other entry criteria may be used to determine when the diagnosis should be performed. The diagnosis may be performed continuously as long as the conditions are correct. If the entry conditions are not met, the system may continue to evaluate the entry criteria until they are met.

[0024] Once the entry conditions are met, the conditions for determining the position of the heater core isolation valve (HCIV) 44 can be checked. The controller can take a measurement of the temperature sensor 48 in the electric heater's own loop and the engine coolant temperature sensor 64 at the engine outlet. The logic can be extended to any heating system with independent heating loops that have different heat sources. The initial temperature values ​​can be stored for later use. The controller can check that the entry conditions continue to be met. If the entry conditions are not met, the system can restart the process. If the entry conditions are met for a calibratable period, the final values ​​of temperature sensor 48 and engine coolant temperature sensor 64 can be measured again.After measuring the temperature values, the initial and final values ​​can be compared to determine the position of the heater core isolation valve (HCIV) 44. A temperature increase in the coolant loop occurs if the difference between the initial and final temperature measurements exceeds a calibratable threshold. The temperature remains constant if the difference between the initial and final temperature measurements is below a calibratable threshold. Determining whether a temperature is increasing or constant can also ensure that the change remains within a predetermined percentage of permissible deviation from a calibratable value.

[0025] The preceding discussion uses temperature measurements taken at two separate times, followed by a calculation of the temperature difference over that time. Alternatively, the two temperature sensor readings can be integrated over time. After a specific time interval, the integrated values ​​can be compared with calibratable thresholds to determine whether the temperature is rising or remaining constant.

[0026] The inlet conditions can be designed such that a temperature increase in the electric heater loop 66 is expected, while a minimal temperature change at the engine coolant outlet is expected. If the inlet conditions are met, the temperature behavior can be observed to determine whether the expected behavior occurs. If the expected behavior occurs, it can be confirmed that the valve is in the correct position. When the electric heater loop 66 is activated and the electric heater 42 is switched on, the temperature 48 in the electric heater loop 66 is expected to increase over time. When the engine 40 is not running, the temperature at the engine coolant outlet is expected to remain constant or change slowly over time.If these conditions are observed, it can be deduced that the heater core isolation valve (HCIV) 44 is in the correct position for the electric heater loop 66.

[0027] If the temperature in the electric heater loop 66 increases and the temperature at the engine coolant outlet remains constant or changes slowly, the controller can infer that the heater core isolation valve (HCIV) 44 is positioned in the electric heater loop 66. Any other measurement conditions may indicate that the heater core isolation valve (HCIV) 44 is not in the correct position. The controller may override the position to display the current position of the heater core isolation valve (HCIV) 44. Further control operations may use the predicted position of the heater core isolation valve (HCIV) 44.

[0028] Fig.Figure 3 shows a flowchart of a possible embodiment of the HCIV position determination. This particular embodiment begins with an initialization step 80, in which counters and variables are cleared. The entry conditions are then evaluated as previously described, 82. If the entry conditions are met, the initial temperature readings of each temperature sensor are stored, 84. If the entry conditions are not met, the system returns to initialization step 80. If the entry conditions are still present, 86, a counter is incremented for each iteration of the control loop, 88. When the counter exceeds a threshold, 90, the final temperature readings of each temperature sensor are stored, 92. The counter can represent the elapsed time of a desired duration. Then, the temperature change for each temperature sensor is determined, 94.Next, the behavior of each temperature sensor is determined, 96. If the temperature change of the electric heater loop 66 is greater than a calibrated value and the temperature change at the engine coolant outlet is less than a calibrated value, then it is deduced that the HCIV is in the correct position in the electric heater loop 66, 100. Any other result of the temperature change comparison means that the HCIV is likely faulty and in the combined heater loop position, 98. It should be noted that the temperature change can also be compared with a deviation from the calibrated value that is permissible within a predetermined percentage.

[0029] If the derived position is not in the trigger position, the controller can set an error code and store a diagnostic code. The controller can also use the derived position to execute the appropriate heating commands based on the position of the HCIV.

[0030] In this particular embodiment, the standard position when not activated is in the combined heating loop. Assuming that supplying current to the control line activates the valve, short circuits and open circuits can be detected by monitoring the control lines.

[0031] While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. The words used in the description are descriptive rather than limiting, and it is understood that various modifications can be made without altering the essence and scope of the invention. Furthermore, the features of different implementation embodiments can be combined to create further embodiments of the invention.

[0032] It is generally described as follows: A vehicle comprising: an engine; a heat exchanger configured to heat a passenger compartment of the vehicle; an electric heater configured to heat the coolant for the heat exchanger; and a valve system comprising a valve configured to selectively direct the coolant from the engine to the heat exchanger and to detect a position of the valve based on a temperature of the coolant entering the heat exchanger and a temperature of 70 of the coolant exiting the engine. Vehicle B according to A, wherein the valve system is configured to detect a position in which the valve does not direct coolant from the engine to the heat exchanger in response to a temperature increase of the coolant entering the heat exchanger being greater than a temperature increase of the coolant exiting the engine, after receiving a command to arrange the valve for fluidic isolation of the engine from the heat exchanger and while the electric heater is switched on and the engine is switched off. C vehicle to B, wherein the temperature increase of the coolant entering the heat exchanger is greater than a first threshold and the temperature increase of the coolant exiting the engine is less than a second threshold. D vehicle to A, wherein the valve system is configured to detect a fault position in which the valve directs the coolant from the engine to the heat exchanger in response to a temperature increase of the coolant entering the heat exchanger and a temperature increase of the coolant exiting the engine, after receiving a command to arrange the valve for fluidic isolation of the engine from the heat exchanger and while the electric heater is switched on and the engine is switched off. E vehicle to D, wherein the fault position is detected if the temperature rise of the coolant entering the heat exchanger is less than a first threshold or the temperature rise of the coolant exiting the engine is greater than a second threshold. F vehicle to D, wherein the valve system is further configured to produce an output representing a disturbance in the valve position. G Vehicle comprising: an engine; a heat exchanger configured to heat a passenger compartment of the vehicle; an electric heater configured to heat the coolant for the heat exchanger; and a valve system comprising a valve configured to selectively direct the coolant from the engine to the electric heater and to detect a position of the valve based on a temperature change of the coolant exiting the electric heater relative to a temperature change of the coolant exiting the engine. H vehicle according to G, wherein the valve system is configured to detect a position in which the valve does not direct coolant from the engine to the electric heater in response to a temperature change of the coolant exiting the electric heater being greater than a temperature change of the coolant exiting the engine, after receiving a command to arrange the valve for fluidic isolation of the engine from the electric heater and while the electric heater is switched on and the engine is switched off. I vehicle according to H, wherein the temperature change of the coolant exiting the electric heater is greater than a first threshold and the temperature change of the coolant exiting the engine is less than a second threshold. J vehicle according to G, wherein the valve system is configured to detect a fault position in which the valve directs the coolant from the engine to the electric heater in response to a temperature change of the coolant exiting the electric heater and a temperature change of the coolant exiting the engine after receiving a command to arrange the valve for fluidic isolation of the engine from the electric heater and while the electric heater is switched on and the engine is switched off. K vehicle to J, wherein the fault position is detected if the temperature change of the coolant exiting the electric heater is less than a first threshold or the temperature change of the coolant exiting the engine is greater than a second threshold. L vehicle to J, wherein the valve system is further configured to produce an output representing a disturbance in the valve position. M Method for detecting a valve position, comprising: activating a pump to circulate the coolant; commanding the valve to pass coolant through a heat source and fluidically isolating the heat source from a motor; activating the heat source; and, in response to the steps of activating and commanding, outputting a signal indicating a position of the valve based on a temperature change of the coolant associated with the heat source and the temperature change of the coolant associated with the motor when the motor is switched off. N method according to M, wherein the engine is switched off for a predetermined period before the valve position is detected. O Method according to M, wherein it is recognized that the valve is in a fault position in which the valve directs coolant from the engine to the heat source when the temperature change of the coolant associated with the heat source is less than a first threshold and the temperature change of the coolant associated with the engine is greater than a second threshold. P method according to M, wherein the valve position is determined as a position in which the valve does not direct coolant from the engine to the heat source when the temperature change of the coolant associated with the heat source is greater than a first threshold and the temperature change of the coolant associated with the engine is less than a second threshold. Q method according to M, wherein the detection of the valve position is performed when an electrical failure for the valve is detected.

Claims

[1] Method for detecting the position of a valve (44) of a vehicle (10), comprising an engine (40), a heat exchanger configured to heat a passenger compartment of the vehicle (10), an electric heater (42) configured to heat a coolant for the heat exchanger, and a valve system comprising the valve (44) configured to selectively direct the coolant from the engine (40) to the heat exchanger, and a controller configured to perform the following process steps: - Measuring the temperature of the coolant entering the heat exchanger, - Measuring the temperature of the coolant exiting the engine (40), - Detecting the position of the valve (44) based on the temperature of the coolant entering the heat exchanger and the temperature of the coolant exiting the engine (40). [2] Method according to claim 1, wherein the control is configured to detect a position in which the valve (44) does not direct coolant from the engine (40) to the heat exchanger in response to a temperature increase of the coolant entering the heat exchanger being greater than a temperature increase of the coolant exiting the engine (40), after receiving a command to arrange the valve (44) for fluidic isolation of the engine (40) from the heat exchanger and while the electric heater (42) is switched on and the engine (40) is switched off. [3] Method according to claim 2, wherein the temperature rise of the coolant entering the heat exchanger is greater than a first threshold and the temperature rise of the coolant exiting the engine (40) is less than a second threshold. [4] Method according to claim 1, wherein the control is configured to detect a fault position in which the valve (44) directs the coolant from the engine (40) to the heat exchanger in response to a temperature increase of the coolant entering the heat exchanger and a temperature increase of the coolant exiting the engine (40), after receiving a command to arrange the valve (44) for fluidic isolation of the engine (40) from the heat exchanger and while the electric heater (42) is switched on and the engine (40) is switched off. [5] Method according to claim 4, wherein the fault position is detected when the temperature rise of the coolant entering the heat exchanger is less than a first threshold or the temperature rise of the coolant exiting the motor (40) is greater than a second threshold. [6] Method according to claim 4, wherein the control further includes the method step of generating an output that represents a disturbance in the valve position.

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