WO2012085294A1

WO2012085294A1 - Motor vehicle controller and method of controlling a motor vehicle

Info

Publication number: WO2012085294A1
Application number: PCT/EP2011/074041
Authority: WO
Inventors: Philippa Laing
Original assignee: Land Rover
Priority date: 2010-12-23
Filing date: 2011-12-23
Publication date: 2012-06-28
Also published as: GB2486708A; GB201021839D0

Abstract

The invention relates to a controller for a motor vehicle (100), the controller being operable to determine which of a plurality of starter devices (121S, 123) is to be used to start an engine (121) of the vehicle (100) responsive to a temperature value determined by the vehicle (100), the controller being operable to select a first starter device (121S) and not a second starter device (123) when a temperature value is below a first threshold value and a second starter device (123) and not a first starter device (121S) when a temperature value is above the first threshold value.

Description

MOTOR VEHICLE CONTROLLER AND METHOD OF CONTROLLING A MOTOR

VEHICLE

FIELD OF THE INVENTION

The present invention relates to a controller and to a method for controlling a motor vehicle and particularly, but not exclusively, to a controller and method for controlling a hybrid electric vehicle (HEV). More particularly but not exclusively the invention relates to a controller and a method for controlling a parallel-type HEV. Aspects of the invention relate to a controller, to a method and to a vehicle.

BACKGROUND

It is known to provide a hybrid electric vehicle (HEV) having an electric machine and an internal combustion engine connected in parallel to a driveline of the vehicle.

The vehicle may be operated in an electric vehicle (EV) mode in which torque to the driveline is provided exclusively by the electric machine. Alternatively the vehicle may be operated in a parallel mode in which torque is provided to the driveline by the internal combustion engine and electric machine.

In some known HEVs, starting of an engine may be performed by means of a conventional starter motor or by means of an alternative electric machine such as a crankshaft integrated motor generator (CIMG) or belt integrated starter/generator (BISG).

It is an aim of embodiments of the present invention to provide improved starting of a HEV. STATEMENT OF THE INVENTION

Aspects of the invention provide a controller, a vehicle and a method as claimed in the appended claims. In another aspect of the invention for which protection is sought there is provided controller for a motor vehicle, the controller being operable to determine which of a plurality of starter devices is to be used to start an engine of a vehicle responsive to a temperature value determined by the controller, the controller being operable to select a first starter device and not a second starter device when a temperature value is below a first threshold value and a second starter device and not a first starter device when a temperature value is above the first threshold value.

Embodiments of the invention have the advantage that an optimum starter device may be chosen to start a vehicle for a given temperature value determined by the controller. The temperature value may for example correspond to an operating temperature of the vehicle. Furthermore, if one starter device is less suitable for use below a certain temperature, for example due to reduced performance or a risk of excessive wear or damage, an alternative starter device may be used instead.

It is to be understood that the temperature value may be a temperature value determined by the controller directly by reference to a sensor, by reference to a signal provided to the controller by a communications network such as a controller area network (CAN), indirectly based on one or more other vehicle parameters, or any other suitable means. A controller according to an embodiment of the invention may be useful in a conventional non-hybrid motor vehicle, in a stop/start motor vehicle or in a hybrid electric vehicle.

Advantageously the controller may be operable to select a plurality of starter devices to start an engine when a temperature value is below a second threshold value that is less than the first threshold value.

Thus in the case of particularly low temperatures, a plurality of starter devices may be employed. This feature has the advantage that where an engine requires an increased amount of torque in order to be cranked, a plurality of starter devices may be employed. Thus where the power available from a single device may be insufficient to start an engine reliably, reliable starting may be ensured.

Similarly, if a performance level of a starter device reduces when at a temperature value below the second threshold value, a plurality of devices may be employed in order to ensure reliable starting. Further advantageously the controller may be operable to select first and second starter devices to start an engine when a temperature value is below the second threshold value.

Thus when the temperature value is below the first threshold value but not below the second threshold value a first starter device may be used and not a second starter device. When the temperature value is below the second threshold value a first and a second starter device may be used.

In some embodiments, the use of two starter motors allows an engine to be started with fewer turns of the engine. This has the advantage that less fuel is passed through an engine before combustion occurs and an engine starts. Thus less fuel is wasted during starting. Furthermore, an amount of undesirable hydrocarbons emitted to the atmosphere (or to which an engine after-treatment system is exposed) is reduced.

This has the advantage that a negative impact of a vehicle upon the environment when initially started at low operating temperatures is reduced. The temperature value may correspond to one selected from amongst an ambient temperature, a temperature of a component of a vehicle and a temperature of a fluid of a vehicle.

Optionally the temperature value corresponds to the temperature of a component of a vehicle and a component is a second starter device.

This has the advantage that if the temperature of a second starter device is below a level at which a second starter device is available to start an engine, a first starter device may be selected to start a vehicle.

It is to be understood that the temperature value may therefore correspond to an operating temperature of a vehicle. The term operating temperature may correspond to a temperature of a portion of a vehicle such as a component or fluid such as an oil, or an ambient temperature of an environment in which a vehicle is operating. Alternatively the term operating temperature may be restricted to a temperature of a vehicle or component or fluid thereof and not include a direct measure of an ambient environmental temperature.

In a further aspect of the invention for which protection is sought there is provided a vehicle having an engine and a plurality of starter devices, the vehicle comprising a controller according to the preceding aspect.

Optionally at least one of the starter devices is an electric machine operable to provide torque assist to one or more wheels of the vehicle when the engine is also driving the wheels.

Examples of electric machines operable to start an engine and provide motive torque include a crankshaft integrated starter generator (CISG), a crankshaft integrated motor generator (CIMG) and a belt integrated starter generator (BISG).

Further optionally at least one of the starter devices is an electric machine operable to provide torque to one or more wheels of the vehicle to drive the vehicle when the engine is off. Optionally the plurality of starter devices and in addition an electric machine are operable to provide torque to drive the vehicle.

The first starter device may comprise one selected from amongst a crankshaft integrated starter generator, a crankshaft integrated motor generator and a starter motor.

The second starter device may comprise one selected from amongst a belt integrated starter generator, a crankshaft integrated motor generator and a crankshaft integrated starter generator.

In one embodiment, the first starter device is a conventional starter motor, optionally a twin solenoid starter (TSS) and the second starter device is one selected from amongst a BISG, a CIMG and a CISG.

Thus, in the case where the second starter is a BISG, in the event that the temperature is below a temperature below which the BISG is unavailable to start the engine, for example due to a risk of excessive slippage of the belt of the BISG or of damage to the belt, the first starter device is employed to start the engine.

It is to be understood that any starter may be employed as the first starter including a BISG, a CIMG, a CISG, a conventional solenoid starter or twin solenoid starter or any other suitable starter. Similarly any starter may be employed as the second starter including a BISG, a CIMG, a CISG, a conventional solenoid starter or twin solenoid starter or any other suitable starter. In a further aspect of the invention for which protection is sought there is provided method of starting an engine of a hybrid electric vehicle having a plurality of starter devices for starting the engine, the method comprising determining which one of the plurality of starter devices to use to start the engine responsive to a temperature value determined by a controller, the controller being operable to select a first starter device and not a second starter device when the temperature value is below a first threshold value and to select the second starter device and not the first starter device when the temperature value is above the first threshold value.

Advantageously the method may comprise the step of selecting a plurality of starter devices to start the engine when the temperature value is below a second threshold value that is lower than the first threshold value, the plurality of starters optionally comprising the first and second starter devices.

Further advantageously the method may comprise the step of selecting the starter device responsive to a temperature value whereby the temperature value corresponds to one selected from amongst an ambient temperature, a temperature of a component of the vehicle and a temperature of a fluid of the vehicle.

Advantageously the first starter device may be one selected from amongst a single solenoid starter motor, a twin solenoid starter motor, a crank integrated starter generator and a crank integrated motor generator and the second starter device is one selected from amongst a belt integrated starter generator, a crank integrated starter generator and a crank integrated motor generator. In one embodiment, the first starter device is a conventional starter motor, optionally a twin solenoid starter (TSS) and the second starter device is one selected from amongst a BISG, a CIMG and a CISG. It is to be understood that any starter device may be employed as the first starter depending on operating temperature characteristics of the particular device and the value of the first temperature threshold value, including a BISG, a CIMG, a CISG, a conventional solenoid starter or twin solenoid starter or any other suitable starter. Similarly any starter may be employed as the second starter depending on operating temperature characteristics of the particular device and the value of the first temperature threshold value, including a BISG, a CIMG, a CISG, a conventional solenoid starter or twin solenoid starter or any other suitable starter.

In an aspect of the invention for which protection is sought there is provided a method of starting an engine of a hybrid electric vehicle having a plurality of starter devices for starting the engine, the method comprising selecting one of the starter devices to start the engine responsive to an operating temperature of the vehicle.

The method may comprise the step of selecting a first starter device when the temperature is below a first threshold value and a second starter device when the temperature is above the first threshold value.

The method may comprise the step of selecting a plurality of starter devices to start the engine when the operating temperature is below a second threshold value.

The second threshold value may be less than the first threshold value.

Alternatively the second threshold value may be substantially equal to the first threshold value.

The starter device is optionally selected responsive to the operating temperature being one selected from amongst an ambient temperature, a temperature of a component of the vehicle and a temperature of a fluid of the vehicle.

Optionally the method comprises the step of selecting the starter device responsive to the temperature of the second starter device. The method may comprises the step of starting the engine by means of one selected from amongst a crankshaft integrated starter generator (CISG), a crankshaft integrated motor generator (CIMG) and a starter motor when the temperature is below the first threshold value.

The method optionally further comprises the step of starting the engine by means of a belt integrated starter generator (BISG) when the temperature is above the first threshold value.

In a further aspect of the invention for which protection is sought there is provided a hybrid electric vehicle (HEV) having a controller, an engine and an electric machine, the electric machine being operable to provide torque to one or more wheels of the vehicle to drive the vehicle, the vehicle having a plurality of starter devices, the controller being operable to determine which of the starter devices is to be used to start the engine responsive to an operating temperature of the vehicle.

One of the plurality of starter devices may comprise the electric machine operable to provide torque to one or more wheels of the vehicle.

It is to be understood that embodiments of the invention are useful in conventional motor vehicles and in hybrid electric vehicles including mild hybrids and full hybrids.

Within the scope of this application it is envisaged that the various aspects, embodiments, examples, features and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings may be taken independently or in any combination thereof. Features described in connection with one embodiments are applicable to all embodiments, except where there is incompatibility of features.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of example only, with reference to the accompanying figures in which: FIGURE 1 is a schematic illustration of a hybrid electric vehicle according to an embodiment of the invention.

DETAILED DESCRIPTION

In one embodiment of the invention a hybrid electric vehicle 100 is provided having an engine 121 coupled to a belt integrated starter generator (BISG) 123. The BISG 123 may also be referred to as a belt integrated (or belt mounted) motor generator. The BISG 123 has an electric machine 123M that is coupled to a crankshaft 121 C of the engine 121 thereby to provide torque thereto by means of a belt 123B. The BISG 123 is operable to provide torque to the crankshaft 121 S when it is required to start the engine 121 or when it is required to provide torque-assist to a driveline 130. By torque-assist is meant that the BISG 123 can provide additional torque to the driveline 130 to drive the vehicle. This allows the amount of torque required to be developed by the engine 121 to be reduced. This in turn allows a reduction in fuel consumption and C0₂ emissions to be enjoyed.

Furthermore in some embodiments this allows a smaller engine 121 to be used for a given amount of maximum required torque thereby allowing a smaller and more efficient engine 121 to be employed.

The crankshaft 121 C is coupled to a transmission 124 of the vehicle 100 by means of a clutch 122. The transmission 124 is in turn coupled to the driveline 130 thereby to drive a pair of front wheels 1 1 1 , 1 12 and a pair of rear wheels 1 14, 1 15.

It is to be understood that other arrangements are also useful. For example the driveline 130 may be arranged to drive the pair of front wheels 1 1 1 , 1 12 only or the pair of rear wheels 1 14, 1 15 only.

The vehicle 100 of FIG. 1 is a stop/start vehicle operable automatically to stop the engine 121 when the vehicle is stationary by a driver brake pedal during the course of a drivecycle. The vehicle 100 is configured automatically to restart the engine 121 when the driver releases the brake pedal. The BISG 123 is operable to provide torque assist to the driveline 130 as noted above but the vehicle 100 is not operable in an electric vehicle (EV) mode in which the vehicle is powered solely by the BISG 123 with the engine 121 switched off. Accordingly the vehicle 100 may be referred to as a 'mild hybrid electric vehicle'.

However, it is to be understood that some embodiments of the invention are suitable for use with other types of hybrid electric vehicle such as full hybrid electric vehicles operable in an EV mode (in which an engine of the vehicle is switched off). Embodiments of the invention are useful in parallel-type hybrid electric vehicles being vehicles operable in an EV mode or a parallel mode, being a mode in which an engine and an electric machine provide torque to drive the vehicle. Some embodiments of the invention are suitable for use with full hybrid electric vehicles having an EV mode and a series mode in which the engine generates electrical power to power an electric machine to provide torque to one or more wheels of the vehicle, the engine not providing torque directly to the driveline. In addition to the BISG 123 the engine 121 of the embodiment of FIG. 1 is also provided with a starter motor 121 S operable to start the engine 121 when required. The starter motor 121 S has a drive pinion operable to engage a pinion of a starter ring gear of a flywheel of the engine 121 when it is required to start the engine 121 . This allows the starter motor to apply torque to crank the enginel 21 . When energised, a solenoid of the starter motor 121 S engages a lever that displaces the drive pinion thereby to engage the starter ring gear. The starter motor 121 S may be a twin solenoid starter motor (TSS) operable to crank the engine 121 whilst the engine is rotating or a conventional starter motor operable to crank the engine only from a substantially stationary condition. Other starter motors 121 S are also useful.

In the embodiment of FIG. 1 the controller 140 is arranged to be provided with a signal responsive to an ambient temperature of the environment in which the vehicle 100 is operating. When the vehicle 100 is first started (at 'key on') and it is required to start the engine 121 , the controller 140 is arranged to determine whether the starter motor 121 S or the BISG 123 should be employed to start the engine 121 . It is to be understood that it is generally preferable for the BISG 123 to be employed due to noise, vibration and harshness (NVH) considerations. This is because the NVH performance of the vehicle 100 is typically better when the BISG 123 is employed rather than the starter motor 121 S. However, the performance of the BISG 123 may be degraded in relatively cold ambient conditions. For example, a rate of wear of components of the BISG 123 such as belt 123B may increase above an acceptable level as temperature falls below a given temperature value. In addition or instead, when a BISG 123 is employed in cold ambient temperatures NVH performance may deteriorate below that which would be experienced if the starter motor 121 S were employed instead of the BISG 123. In some cases noise due to slippage of the belt of the BISG 123 in low ambient temperature conditions can become unacceptably high. Accordingly, when the engine 121 is first started in a given drive cycle the controller 140 is arranged to select only the starter motor 121 S to start the engine 121 when the ambient temperature is below a prescribed threshold level. In the present embodiment the temperature is selected to be around -10°C although other temperatures are also useful. In some embodiments the threshold level is selected to be a temperature below which NVH performance of the vehicle 100 when started with the BISG 123 is below that of the vehicle 100 when started using the starter motor 121 S. Other conditions and other arrangements are also useful for determining the threshold level.

In some embodiments the prescribed threshold level may be higher than that at which the NVH performance of the BISG 123 is less than that of the starter motor 121 S, for example in cases where the BISG 123 has a higher minimum operating temperature specified by a manufacturer.

In some embodiments the controller 140 is configured to determine a temperature of a portion of the BISG 123 and to employ the BISG 123 to start the engine 121 only if the temperature of the portion of the BISG 123 exceeds the prescribed threshold value.

Furthermore, the controller 140 may be configured to determine the temperature of the BISG 123 each time it is required to start the engine 121 within a given drivecycle.

In embodiments in which a different temperature is employed such as an ambient temperature, an engine coolant temperature or any other temperature, again the controller 140 may be configured to determine which starter device to employ each time the engine 121 is started during the course of a drivecycle responsive to the temperature. It is to be understood that if the vehicle 100 is operating in particularly cold ambient temperatures and the vehicle 100 is stationary for an extended period of time during a drivecycle with the engine off, for example in queuing traffic, the temperature of the BISG 123 may fall below the threshold value. Having a controller 140 that checks the temperature each time the engine 121 is to be started and selects an appropriate starter device 121 S, 123 is advantageous. This is because a risk that one of NVH performance or starting performance is degraded unnecessarily due to a low operating temperature may be reduced. In addition or instead, a longevity of one or more components of the vehicle such as a starter motor 121 S or BISG 123 may also be improved. For example, in some cases a BISG 123 may suffer damage or excessive wear when operated below a prescribed temperature. This may be due at least in part to an effect of temperature on a material from which the belt 123B is made, or any other component of the BISG 123 or components with which the BISG 123 interacts.

It is to be understood that other arrangements are also useful.

It is to be further understood that a number of turns of the engine 121 required to be made before the engine 121 is started may also be increased if the BISG 123 (or another starter more suitable for higher temperature operation) is employed at low temperatures. This may result in increased emissions during starting and increased fuel wastage. By employing the starter motor 121 S instead of the BISG 123, the amount of undesirable emissions and of fuel usage may be reduced.

In some embodiments, the controller 140 is configured to control the vehicle 100 to start the engine 121 using the starter motor 121 S and BISG 123 together when the temperature is below a second threshold temperature lower than the first threshold described above. The second threshold temperature may be in the range from around - 35°C to around -40 °C although other temperature ranges are also useful. It is to be understood that in particularly cold ambient temperatures, starting by means of the starter motor 121 S alone may not be possible or may result in excessively long crank times. By employing the BISG 123 and starter motor 121 S in such circumstances one or more of these problems may be alleviated. In some embodiments, a starter other than the second starter (the second starter being the BISG 123 in the present embodiment) such as the first starter (being the starter 121 S in the present embodiment) may be employed if the operating temperature is above a high temperature threshold value being a value higher than the first threshold value. For example if the operating temperature is too high for reliable BISG 123 operation a different starter (such as starter motor 121 S) may be employed.

For example in some embodiments the temperature of the second starter may be too high due to operation of the second starter for extended periods in relatively high ambient temperatures. Therefore a different starter may be employed, such as the first starter.

Embodiments of the invention have the advantage that operation of a vehicle according to an embodiment of the invention may be enhanced by providing one or more of the advantages described above whilst operating in low temperature conditions. The advantages may include faster starting, more reliable starting, reduced fuel consumption, reduced wear and reduced NVH.

Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", means "including but not limited to", and is not intended to (and does not) exclude other moieties, additives, components, integers or steps.

Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

Claims

CLAIMS:

1 . A controller for a motor vehicle, the controller being operable to determine which of a plurality of starter devices is to be used to start the engine of the vehicle in dependence on a temperature value, the controller being operable to select a first starter device only when a temperature value is below a first threshold value and a second, different starter device only when a temperature value is above the first threshold value.

2. A controller as claimed in claim 1 and operable to select a plurality of starter devices to start the engine when a temperature value is below a second threshold value that is less than the first threshold value.

3. A controller as claimed in claim 2 and operable to select both first and second starter devices to start the engine when a temperature value is below the second threshold value.

4. A controller as claimed in any preceding claim wherein said temperature value corresponds to at least one selected from amongst an ambient temperature, a temperature of a component of the vehicle and a temperature of a fluid of the vehicle.

5. A controller as claimed in claim 4 wherein said temperature value is a temperature of the second starter device.

6. A vehicle having an engine and a plurality of starter devices, the vehicle comprising a controller as claimed in any preceding claim.

7. A hybrid electric vehicle as claimed in claim 6 wherein at least one of the starter devices is an electric machine operable to provide torque assist to one or more wheels of the vehicle when the engine is also driving the wheels.

8. A hybrid electric vehicle as claimed in claim 6 or claim 7 wherein at least one of the starter devices is an electric machine operable to provide torque to one or more wheels of the vehicle to drive the vehicle when the engine is off.

9. A vehicle as claimed in any one of claims 6 to 8 wherein the plurality of starter devices and in addition an electric machine are operable to provide torque to drive the vehicle.

10. A vehicle as claimed in any one of claims 6 to 9 wherein the first starter device comprises one selected from amongst a crankshaft integrated starter generator, a crankshaft integrated motor generator and a starter motor.

1 1 . A vehicle as claimed in any one of claims 6 to 10 wherein the second starter device comprises one selected from amongst a belt integrated starter generator, a crankshaft integrated motor generator and a crankshaft integrated starter generator.

12. A method of starting an engine of a hybrid electric vehicle having a plurality of starter devices for starting the engine, the method comprising:

detecting a temperature value;

selecting a first starter device only to start the engine when the temperature value is below a first threshold value;

select a second starter device only to start the engine when the temperature value is above the first threshold value; and

starting the engine using the selected starter device.

13. A method as claimed in claim 12 comprising the step of selecting a plurality of starter devices to start the engine when the temperature value is below a second threshold value that is lower than the first threshold value, the plurality of starters optionally comprising the first and second starter devices.

14. A method as claimed in any one of claims 12 to 13 comprising the step of selecting the starter device responsive to a temperature value whereby the temperature value corresponds to one selected from amongst an ambient temperature, a temperature of a component of the vehicle and a temperature of a fluid of the vehicle.

15. A method as claimed in any one of claims 12 to 14 wherein the first starter device is one selected from amongst a single solenoid starter motor, a twin solenoid starter motor, a crank integrated starter generator and a crank integrated motor generator and the second starter device is one selected from amongst a belt integrated starter generator, a crank integrated starter generator and a crank integrated motor generator.