Running a PHEV in EV mode under cold conditions

A plug-in hybrid electric vehicle has an internal combustion engine with a coolant outlet connected to a coolant inlet of a fuel operated heater and wherein a coolant outlet of the fuel operated heater is connected to a coolant inlet of an HVAC heater, a coolant outlet of the HVAC heater further being connected to a coolant inlet of the internal combustion engine. The vehicle also has a temperature sensor at the coolant outlet of the internal combustion engine and a temperature sensor at the coolant outlet of the fuel operated heater. The vehicle has a three way valve arranged between the coolant outlet of the HVAC heater and the coolant inlet of the internal combustion engine such that there is a connection between the coolant outlet of the HVAC heater and the coolant inlet of the fuel operated heater, the connection bypassing the internal combustion engine.

FIELD OF THE INVENTION

The present invention relates to a plug-in hybrid electric vehicle comprising an internal combustion engine, a coolant outlet of the internal combustion engine being connected to a coolant inlet of a fuel operated heater and wherein a coolant outlet of the fuel operated heater is connected to a coolant inlet of an HVAC heater, a coolant outlet of the HVAC heater further being connected to a coolant inlet of the internal combustion engine, the vehicle further comprising a temperature sensor arranged at the coolant outlet of the internal combustion engine and a temperature sensor arranged at the coolant outlet of the fuel operated heater.

BACKGROUND

A plug-in hybrid electric vehicle with an internal combustion engine is generally not feasible to run in pure electric drive mode at ambient temperatures below 15° C. since the fuel operated heater combined with an electric pump is not sufficient for providing the requested passenger compartment and internal combustion engine thermal targets (the latter to facilitate acceptable vehicle take-off performance at driving mode shift from electrical drive mode to an ICE-initiated one (e.g. HEV, ICE-drive or AWD)). In a regular hybrid vehicle, i.e. a vehicle that only runs short distances on electric drive, heating is not an issue since the internal combustion engine is run regularly which helps increase the temperature of the coolant sufficiently for a period of pure electric drive while maintaining requested internal combustion engine and passenger compartment temperatures.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a system and a method for controlling the thermal power generated by the fuel operated heater and the internal combustion engine of a plug-in hybrid in such a way that pure electric drive feasibility is maximised in time and in ambient temperature range such that it is extended below 15° C. and as far down as −40° C. and, moreover, the climate system electric power consumption at and above an ambient temperature of 25° C. is minimised.

This object is achieved with a system and a method according to the enclosed claims.

According to one aspect of the present invention a plug-in hybrid electric vehicle comprises an internal combustion engine, a coolant outlet of the internal combustion engine being connected to a coolant inlet of a fuel operated heater and wherein a coolant outlet of the fuel operated heater is connected to a coolant inlet of an HVAC heater. A coolant outlet of the HVAC heater is further connected to a coolant inlet of the internal combustion engine, the vehicle further comprising a temperature sensor arranged at the coolant outlet of the internal combustion engine and a temperature sensor arranged at the coolant outlet of the fuel operated heater. The vehicle further comprises a three way valve arranged between the coolant outlet of the HVAC heater and the coolant inlet of the internal combustion engine such that there is a connection between the coolant outlet of the HVAC heater and the coolant inlet of the fuel operated heater, the connection thus bypassing the internal combustion engine.

The bypass of the internal combustion engine is one of the factors contributing to the possibility to run a vehicle on pure electric drive at cold weather while fulfilling both climate system and internal combustion engine thermal targets. For instance, in a situation where the vehicle has not been running for several hours the engine and the coolant temperatures are more or less equal to the ambient temperature. If the ambient temperature is about 0° C., by fully bypassing the internal combustion engine at electrical drive, the fuel operated heater will be able to provide sufficient heat to relatively fast warm up the passenger compartment to a desired temperature and thereafter a partial bypassing of the internal combustion engine will provide sufficient heat to fulfil its thermal targets while maintaining the passenger compartment temperature at climate comfort. Without the bypass the internal combustion engine would cool down the coolant to such an extent that the fuel operated heater would never alone be able to handle the passenger compartment heating. For a fuel operated heater to alone manage this it would have to be dimensioned such that it would not be realistic to incorporate into the vehicle and would also be energy inefficient requiring large amounts of energy to run, i.e. the fuel economy and the environment would suffer from this. Moreover, by fully bypassing the cabin heater at and above 25° C. ambient temperature at an internal combustion engine-initiated or electrical drive mode the electrical power needed to fulfil the climate system thermal targets is reduced and minimised.

According to another aspect of the present invention the vehicle further comprises an electrical pump upstream the coolant inlet of the fuel operated heater. When none or a limited part of the coolant flows through the internal combustion engine or when the internal combustion engine is not running, i.e. at electrical drive, the coolant circuit needs a pump to circulate the coolant through the fuel operated heater and the HVAC heater.

According to yet another aspect of the present invention the vehicle further comprises a mechanical pump upstream the coolant inlet of the internal combustion engine. This pump is preferably a more or less integrated part of the engine such that it runs when the internal combustion engine is running.

The three way valve is according to one aspect of the present invention an electromagnetic valve. An electromagnetic valve can be controlled such that it opens and closes with different frequencies in order to allow for varying flows, for instance, a 70/30, 50/50, or 30/70 flow.

According to a further aspect of the present invention three way valve is a vacuum valve. If there is a vacuum system available a vacuum valve is both cheaper and lighter compared to an electromagnetic valve.

A further possibility would be to use a standard continuous electric machine driven control valve which could vary from 0 to 100% coolant flow that stays in a specific position as compared to the electromagnetic valve which is either closed or open as a function of time.

DISCLOSURE OF PREFERRED EMBODIMENTS

FIG. 1shows an internal combustion engine1, a coolant outlet2of the internal combustion engine1that is connected to a coolant inlet3of a fuel operated heater4and wherein a coolant outlet5of the fuel operated heater4is connected to a coolant inlet6of an HVAC heater7, a coolant outlet8of the HVAC heater7further being connected to a coolant inlet9of the internal combustion engine1. Also shown is a temperature sensor10arranged at the coolant outlet2of the internal combustion engine1and a temperature sensor11arranged at the coolant outlet5of the fuel operated heater4.

FIG. 1further shows a three way valve12arranged between the coolant outlet8of the HVAC heater7and the coolant inlet9of the internal combustion engine1such that there is a connection13between the coolant outlet8of the HVAC heater7and the coolant inlet3of the fuel operated heater4, the connection13thus bypassing the internal combustion engine1. An electrical pump14will run when the short flow circuit is fully or partially used at all plug-in hybrid electric vehicles' (PHEV) driving modes or when the long flow circuit is used at electrical drive mode and a mechanical pump15will run when the internal combustion engine1is running.

To make electrical drive feasible at and below 15° C. ambient temperature with fulfilled climate system and internal combustion engine (ICE) thermal targets (the latter to facilitate acceptable vehicle take-off performance at driving mode shift from electrical drive mode to an ICE-initiated one (e.g., HEV, ICE-drive or AWD)) as well as reduce and minimise the electrical power needed to fulfil the climate system thermal targets at and above 25° C. ambient temperature.the ICE-cabin heater coolant circuit is split into two by a valve that controls the coolant water flow through both and as a consequence the thermal power distribution to the ICE and the cabin heater, seeFIG. 1,a modular valve control strategy that efficiently considers all the PHEV driving modes (i.e. EV-, HEV-, and ICE-drive-modes) and different thermal initial conditions, by optimally dealing with a simultaneous or an individual fulfilment of ICE's and climate system's thermal power needs/targets. This modular control strategy (where the control algorithm different modules can be reused, activated or deactivated at the different initial and operational conditions) reduces system solution complexity, decreases needed software variations, and improve robustness whereas paving the way for an efficient introduction of the whole system (i.e., hardware and software) to any other existing or future vehicle (e.g., EV-, HEV-, PHEV-, or ICE-drive-vehicle) with positive impact on product development, production, and production costs,a short time limited, power consumption efficient, and sparking-plugs durability accounted ICE's plugs pre-glow dependant on PHEV's electrical drive mode shift-arising information (e.g. gas pedal angle at overtaking or high voltage battery state of charge level close to sustaining) to an ICE-initiated one (e.g., HEV, ICE-drive or AWD) that considers ICE's thermal power needs related to vehicle take-off target at such PHEV-driving mode shift at cold climate at and below 15° C. ambient temperature until the coolant water temperature at ICE-side is at or above the ICE's thermal targets, anda climate control system's “ICE-Start”-control strategy where the ICE operates as an additional heater, to further extend EV-drive feasibility below 0° C. down to about −40° C. ambient temperature with fulfilled ICE's- and climate system-targets
have been developed and implemented to fulfil and extend electrical drive feasibility between 15° C. and about −40° C. ambient temperature as well as minimise climate system electrical power needs at and above 25° C. ambient temperature (which benefits both OEM and final customer) while fully extracting and utilizing the PHEV technologies full capacities.

The following is a description of how the system is controlled under various conditions.

I—Cold climate electrical drive climate system control strategy at cold start, i.e. 0° C.≦Tamb=TICE-out=TFOH-out≦15° C.

1—request the fuel operated heater (FOH) start (including electrical water pump).2—request closed valve, i.e. coolant volume flow is limited to FOH-SFC () until=x [min] or TFOH-out=Y [° C.] (where Y<TFOH-half), then allow a partial coolant volume flow=v through the valve to ICE (while the FOH-short flow circuit (FOH-SFC) coolant volume flow remain v, i.e. total coolant volume flow is+v<V). Thereafter, at=X [min] or TFOH-out=TFOH-half−y [° C.], request open valve until TICE-out=TICE-target, then the valve control will allow a partial coolant volume flow=V to the ICE to maintain TICE-out=TICE-targetwhile the reminder of the thermal power generated by FOH is used to approach and maintain climate comfort through the FOH-SFC volume flow () where the total coolant volume flow is ν+V.3—If TFOH-out=TFOH-half−y [° C.] then request open valve until TFOH-out=TFOH-half−γ[° C.] where γ−y=5° C. then allow a partial volume flow=again and so on for=χ[min]. Thereafter, TFOH-outwill approach TFOH-halfand the FOH will shift to operate at half-power/capacity. If TFOH-out=TFOH-full+y [° C.] then request closed valve until TFOH-out=TFOH-full+γ [° C.] (where γ−y=5° C.) then allow a partial volume flow=once again and so on for=x[min]. Thereafter, Thereafter, TFOH-outwill approach TFOH-fulland the FOH will shift to operate at full-power/capacity, and so on. The reason for that is to damp down any eventual quick fluctuation of the FOH operation between its full and half power/capacity which is harmful for it when dealing with durability.4—If TFOH-out=TFOH-off−y [° C.] then request open valve to avoid FOH turn off during electrical vehicle drive below 15° C. ambient temperature. If, thereafter, TFOH-outapproaches TFOH-out=TFOH-half−γ [° C.] then follow I-3 above.5—A short time limited ICE-plugs pre-glow dependant on drive mode shift-arising information (e.g. gas pedal angle at overtaking or high voltage battery state of charge level close to sustaining) will be used to achieve a power consumption efficient and take-off acceptable PHEV-mode shift (from EV- to HEV-, ICE-, or AWD-drive mode) performance. This ICE-plugs pre-glow will be available until=X [min] or TICE-out≧TICE-target.
II—Cold climate, i.e. ˜−8° C.≦Tamb≦15° C., electrical drive climate system control strategy of a FOH-preconditioned or warm started vehicle, where TICE-out<TICE-FOH-on-reqand TICE-out≦TFOH-out<TFOH-off
If ˜−8° C.≦Tamb≦15° C. and TICE-out<TICE-FOH-on-reqand TICE-out≦TFOH-out<TFOH-off(e.g. after a timer start FOH-based preconditioning), at electrical drive “key-on” then request control strategy as at I above.
III—Cold climate, i.e. ˜−8° C.≦Tamb≦15° C., electrical drive climate system control strategy of a FOH-preconditioned or warm started vehicle, where TICE-out>TICE-FOH-on-reqand TFOH-out≧TICE-out
If ˜−8° C.≦Tamb≦15° C. and TICE-out>TICE-FOH-on-reqand TFOH-out≧TICE-out(e.g. after a direct start (DS) FOH-based preconditioning), i.e. FOH is off, at electrical drive “key-on” then:1—request the electrical water pump to start2—FOH will remain off until TICE-out=TICE-FOH-on-reqthen it will turn on where the valve remain open until TFOH-out>TICE-out+Y [° C.] and then it requested closed, i.e. coolant volume flow is limited to FOH-SFC (ν).3—IF TFOH-outapproach TFOH-out=TFOH-half−y [° C.] then go to I-3 and 4 above.4—if TICE-outapproach TICE-targetthe valve control will allow a partial coolant volume flow=V to ICE to maintain TICE-out=TICE-targetwhile the reminder of the thermal power generated by FOH is used to approach and maintain climate comfort through the FOH-SFC volume flow (ν).5—No short time limited ICE-plugs pre-glow will be needed in this case.
IV—Cold climate electrical drive climate system control strategy at cold start, i.e. −40° C.<Tamb=TICE-out=TFOH-out<0° C.
If ˜−40° C.≦Tamb=TICE-out=TFOH-out≦0° C. at electrical drive “key-on” then:1—request both ICE and FOH (including electrical water pump) to turn on as well as open valve until TICE-outapproaches TICE-ICE-off-reqthen turn off the ICE, i.e. allow electrical drive.2—at TICE-out≦TICE-FOH-on-req−(wherevaries with Tamb) the valve control will follow III-2 above (i.e. when TFOH-out>TICE-out+Y [° C.] request closed valve) and otherwise (at TICE-out>TICE-FOH-on-reg−the valve will be open.3—when TFOH-outapproaches TFOH-ICE-on-regturn on the ICE (i.e. electrical drive comes to an end) until TICE-outapproaches TICE-ICE-off-regthen turn off the ICE once again and so on until the high voltage battery state of charge level achieve the sustaining one and the vehicle shifts to HEV-driving mode. The number of electrical drive interruptions by ICE-start depends, among other things, on Tamband vehicle speed.
V—Cold climate, i.e. −40° C.<Tamb<0° C., electrical drive climate system control strategy at warm start, i.e. TFOH-out>TFOH-ICE-on-req
If ˜−40° C.≦Tamb<0° C. and TFOH-out>TFOH-ICE-on-reqat electrical drive at electrical drive “key-on” then:1—the FOH will turn on (including electrical water pump) and the ICE will remain off (i.e. electrical drive is feasible) until TFOH-out=TFOH-ICE-on-reqwhere the ICE will turn on (i.e. electrical drive comes to an end) until TICE-out=TICE-ICE-off-reqwhere it (the ICE) will turn off (i.e. electrical drive is feasible once again) and so on until the high voltage battery state of charge level achieve the sustaining one and the vehicle shifts to HEV-driving mode.2—the valve control will follow IV-2 above.3—Again, the number of electrical drive interruptions by ICE-start depends on Tamband vehicle speed.
VI—Cold climate, i.e. −40° C.<Tamb<0° C., electrical drive climate system control strategy at warm start, i.e. TFOH-out<TFOH-ICE-on-req
If ˜−40° C.≦Tamb<0° C. and TFOH-out<TFOH-ICE-on-reqat electrical drive at electrical drive “key-on” then:1—both ICE and FOH (including electrical water pump) will turn on (i.e. electrical drive is not feasible) until TICE-out=TICE-ICE-off-reqwhere the ICE will turn off (i.e. electrical drive is feasible) until TFOH-out=TFOH-ICE-on-reqwhere the ICE will turn on once again (i.e. electrical drive comes to an end) and so on until the high voltage battery state of charge level achieve the sustaining one and the vehicle shifts to HEV-driving mode.2—the valve control will follow IV-2 above.3—Again, the number of electrical drive interruptions by ICE-start depends on Tamband vehicle speed.
VII—Cold climate HEV (i.e. Hybrid-Sustaining)-drive climate system control strategy at cold start, i.e. −40° C.≦Tamb=TICE-out=TFOH-out≦15° C.
If ˜−40° C.≦Tamb=TICE-out=TFOH-out≦15° C. at HEV (i.e. Hybrid-Sustaining)-drive “key-on” where the vehicle shifts between ICE- and electrical machine drive within a certain high voltage battery state of charge interval, then:1—request FOH-start (including electrical water pump) and open valve, i.e. coolant volume flow is V.2—when TFOH-out>TICE-out+Y [° C.] then request closed valve, i.e. coolant volume flow is limited to FOH-SFC (ν) until TFOH-out<TICE-out−Y [° C.] then request open valve and so on until TFOH-out=TICE-FOH-off-reqthen the FOH will turn off and the valve will remain open as at its default position.3—when TICE-out=TICE-FOH-on-reqthen the FOH will restart and the above mentioned control strategy at 2 will be re-performed.
VIII—Cold climate HEV (i.e. Hybrid-Sustaining)-drive, i.e. −40° C.<Tamb<15° C., climate system control strategy at warm start where TICE-out<TICE-FOH-on-reqor TICE-out>TICE-FOH-on-reqand TFOH-out≧TICE-out
If ˜−40° C.≦Tamb<15° C. and TICE-out>TICE-FOH-on-reqat HEV (i.e. Hybrid-Sustaining)-drive “key-on” then the FOH will remain off until TICE-out=TICE-FOH-on-reqwhere it will turn on (including electrical water pump) and the above mentioned control strategy at VII-2 and 3 will be performed.
If ˜−40° C.≦Tamb<15° C. and TICE-out<TICE-FOH-on-reqat HEV (i.e. Hybrid-Sustaining)-drive “key-on” then the FOH will turn on (including electrical water pump) and the above mentioned control strategy at VII-2 and 3 will be performed.
IX—Cold climate ICE- and AWD-drive climate system control strategy at cold start, i.e. −40° C.≦Tamb=TICE-out=TFOH-out≦15° C. or warm start, where TICE-out<TICE-FOH-on-reqor TICE-out>TICE-FOH-on-reqand TFOH-out≧TICE-out
Operation is similar as at HEV-driving mode at VII and VIII with the exception of having ICE continuously running during the driving mode which further limits the needs of FOH as a supplementary heater.
X—Warm climate HEV-, ICE- and AWD-drive climate system control strategy at cold start, i.e. 25° C.≦Tamb=TICE-out=TFOH-outor warm start, where TICE-out≈TFOH-out>Tamb≧25° C.
If 25° C.≦Tamb=TICE-out=TFOH-outor TICE-out≈TFOH-out>Tamb≧25° C. at PHEV drive mode where the ICE is on (e.g. HEV-, ICE- or AWD-drive) then request closed valve. The FOH and electrical pump will remain off and the ICE driven mechanical pump will circulate the coolant water within the ICE-part of the coolant circuit but not the short flow circuit, i.e. the cabin heater- and FOH-part of the coolant circuit.
XI—Warm climate electrical drive climate system control strategy at cold start, i.e. 25° C.≦Tamb=TICE-out=TFOH-outor warm start, where TICE-out≈TFOH-out>Tamb≧25° C.
If 25° C.≦Tamb=TICE-out=TFOH-outor TICE-out≈TFOH-out>Tamb≧25° C. at electrical drive then request closed valve while the FOH and electrical pump will remain off.
The foregoing is a disclosure of an example practicing the present invention. However, it is apparent that method incorporating modifications and variations will be obvious to one skilled in the art. Inasmuch as the foregoing disclosure is intended to enable one skilled in the art to practice the instant invention, it should not be construed to be limited thereby, but should be construed to include such modifications and variations as fall within the scope of the claims.

DEFINITIONS

ICE Internal Combustion EngineFOH Fuel Operated HeaterOperation timeTambAmbient temperatureV Coolant water volume flow through the ICE coolant circuit at open valveν Coolant water volume flow through the FOH's short flow circuit (FOH-SFC) at closed valvePartial coolant water volume flow through the valve to ICE where≦ν≦V, and=ν=V at open valveTFOH-outCoolant temperature after the FOHTICE-outCoolant temperature after the ICETHVAC-inCoolant temperature before cabin heaterTHVAC-outCoolant temperature after cabin heaterTFOH-offFOH's coolant temperature that requests FOH to turn-offTFOH-halfFOH's coolant temperature that requests FOH to operate at half power/capacityTFOH-fullFOH's coolant temperature that requests FOH to operate at full power/capacity while it is operating at half power/capacityTICE-targetICE's coolant temperature that is required to approach an acceptable vehicle take-off performance at mode shift from electrical drive to an ICE initiated oneTICE-FOH-on-reqICE's coolant temperature that requests FOH to turn-on as an additional heaterTICE-FOH-off-reqICE's coolant temperature that requests FOH to turn-off as an additional heaterTFOH-ICE-on-reqFOH's coolant temperature that requests ICE to turn-on as an additional heaterTICE-ICE-off-reqICE's coolant temperature that requests ICE to turn-off as an additional heater