GB2523666A

GB2523666A - Hybrid vehicle

Info

Publication number: GB2523666A
Application number: GB1502790.7A
Authority: GB
Inventors: Sreenath Reghunath; Ashwini Athreya; Deepak Sharma; Anand Prasanna
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2015-02-19
Filing date: 2015-02-19
Publication date: 2015-09-02
Also published as: GB201502790D0

Abstract

Hybrid vehicle with internal combustion engine, exhaust after-treatment device (e.g. DPF), electrical heater to heat exhaust after-treatment device, electric machine operable as a generator to receive torque to slow the vehicle (i.e. regenerative braking) and output electrical power, and an energy storage device (i.e. battery). A prediction module outputs a parameter indicating a limitation of predicted energy supply to energy storage device, possibly during generator mode, and electrical power is distributed between battery and electrical heater on the basis of the anticipated energy supply. Predicted parameter may be an l2t limitation, may comprise a state of charge saturation of the energy storage device, and may be based on a projected route segment on which the vehicle is predicted to travel, the predicted route possibly being determined by means of a navigation system (e.g. GPS). A method of operation is also included.

Description

Hybrid Vehicle The invention relates to a hybrid vehicle according to the preamble of patent claim 1.

Hybrid vehicles are well-known from the general prior art. Such a hybrid vehicle comprises an internal combustion engine and at least one electric machine operable in a motor mode to drive the vehicle by means of the electric machine acting as a motor.

Moreover, the internal combustion engine is configured to drive the vehicle. The internal combustion engine is operable to output exhaust gas. Moreover, the hybrid vehicle comprises an exhaust aftertreatment device configured to receive the exhaust gas from the internal combustion engine. Usually, the exhaust after treatment device has a light-off temperature from which the exhaust gas can be aftertreated by means of the exhaust aftertreatment device particularly effectively and efficiently. Thus, it is desirable to heat the exhaust aftertreatment device during operation of the internal combustion engine so that the exhaust aftertreatment device reaches the light-off temperature particularly fast.

Usually, the exhaust aftertreatment device is heated by the exhaust gas provided by the internal combustion engine. However, in a hybrid vehicle the temperature of the exhaust gas can be particularly low most of the time since the hybrid vehicle can be driven by means of the electric machine solely or with the help of the electric machine. Hence, it is known to use an electrical heater operable to heat the exhaust aftertreatment device using electrical power.

US 8 473 177 B2 shows a hybrid vehicle of the kind indicated in the preamble of patent claim 1. The hybrid vehicle comprises an internal combustion engine operable to output exhaust gas. The hybrid vehicle further comprises an exhaust aftertreatment device configured to receive the exhaust gas from the internal combustion engine. Moreover, the hybrid vehicle comprises at least one electrical heater operable to heat the exhaust aftertreatment device. The hybrid vehicle also comprises at least one electric machine operable in a generator mode to receive torque to slow the hybrid vehicle and output electrical power. Moreover, the hybrid vehicle comprises at least one energy storage device such as a battery, the energy storage device being operable to be supplied with and store electrical power from the electric machine in the generator mode. The hybrid vehicle further comprises a controller operable in the generator mode to control the electrical heater to heat the exhaust aftertreatment device using electrical power from the electric machine in the generator mode. Thereby, the exhaust aftertreatment device can be heated by the electrical heater when, for example, the internal combustion engine is switched off or the internal combustion engine is running but the temperature of the exhaust gas is too low for sufficiently heating the exhaust aftertreatment device. In such a case the exhaust aftertreatment device can be heated by the electrical heater so that the exhaust aftertreatment device reaches or keeps the light-off temperature.

It is an object of the present invention to provide a hybrid vehicle of the aforementioned kind, in which hybrid vehicle a particularly high efficiency of the exhaust aftertreatment device can be realized.

This object is solved by a hybrid vehicle having the features of patent claim 1.

Advantageous embodiments with expedient developments of the invention are indicated in the other patent claims.

In order tor provide a hybrid vehicle of the kind indicated in the preamble of patent claim 1, in which hybrid vehicle a particularly high efficiency of the exhaust aftertreatment device can be realized, according to the present invention the controller comprises a prediction module configured to predict at least one parameter indicative of a limitation of the supply of the energy storage device with electrical power from the electric machine in the generator mode, the limitation possibly occurring during the generator mode, wherein the controller is configured to distribute the electrical power provided by the electric machine in the generator mode at least among the energy storage device and the electrical heater on the basis of the predicted parameter. Thereby, an available potential energy of the hybrid vehicle can be used particularly efficiently to heat the exhaust aftertreatrnent device in the generator mode.

For example, by predicting and, thus, considering the parameter and, thus, the limitation possibly occurring during the generator mode, current the energy storage device is fed with during the generator mode can be kept low so that remaining recuperation potential can be utilized for the electrical heater by the electrical machine in the generator mode so as to heat the exhaust aftertreatment device thereby realizing a particularly high efficiency of the exhaust aftertreatment device. Thus, the exhaust aftertreatment device can be heated so that its temperature can be kept at or above the light-off temperature of the exhaust aftertreatment device. Hence, reduction in efficiency of the exhaust aftertreatment device due to hybridization can be avoided.

For example, electrical power provided by the electric machine in the generator mode is routed from the electric machine directly to the electrical heater on the basis of the predicted parameter so that the exhaust aftertreatment device can be heated particularly efficiently. For example, at the start of a downhill slope the parameter effecting the supply of the energy storage device with electrical power is predicted for the whole downhill slope. The parameter can be predictively monitored during the downhill slope so as to supply electrical heater with electrical power provided by the electric machine in the generator mode on the basis of the monitored parameter. Thereby, the potential of the hybrid vehicle travelling down the slope can be used and extracted at least substantially completely to heat the exhaust aftertreatment device so that aftertreatment efficiency detonation can be minimized. Moreover, fuel economy can be increased as auxiliary load on the internal combustion engine can be reduced. Moreover, the life of the energy storage device which is, for example, a battery, can be improved.

Preferably, the parameter comprises an 12t limitation, wherein 12t terms the melting integral. Alternatively or additionally, the parameter comprises a state of charge saturation (SOC saturation) of the energy storage device. This means 12t and/or SOC saturation are predictively monitored by means of the prediction module.

Preferably, the parameter is predicted on the basis of a route segment on which the hybrid vehicle will possibly travelling in the near future, the controller being configured to determine the route segment by means of a navigation system of the hybrid vehicle.

Further advantages, features, and details of the invention derive from the following description of a preferred embodiments as well as from the drawing. The features and feature combinations previously mentioned in the description as well as the features and feature combinations mentioned in the following description of the figures and/or shown in the figures alone can be employed not only in the respective indicated combination but also in any other combination or taken alone without leaving the scope of the invention.

The drawing shows in: Fig. 1 three diagrams illustrating a method for operating a hybrid vehicle, in which method a prediction module of a controller predicts at least one parameter indicative of a limitation of a supply of an energy storage device with electrical power from an electric machine in a generator mode, the limitation possibly occurring during the generator mode, wherein the controller distributes electrical power provided by the electric machine in the generator mode at least among the energy storage device and an electrical heater on the basis of the predicted parameter; and Fig. 2 four graphs illustrating said method according to Fig. 1.

In the figures the same elements or elements having the same functions are indicated by the same reference signs.

Figs. 1 and 2 show a diagram 10 having an ordinate 12 showing an altitude of a hybrid vehicle 15. Moreover, the diagram 10 has an abscissa 14 showing the time. All abscissas 14 in Figs. 1 and Fig. 2 show the time. Thus, a graph 16 in the diagram 10 illustrates the altitude of the hybrid vehicle 15 versus the time. As can be seen from Fig. 2, the hybrid vehicle 15 is at a starting point A of a downhill slope which ends at an endpoint B. In the present case, the hybrid vehicle 15 is configured as a commercial vehicle.

Alternatively, the hybrid vehicle 15 can be a passenger vehicle. The hybrid vehicle 15 comprises an internal combustion engine operable to output exhaust gas. Moreover, the hybrid vehicle 15 comprises an exhaust aftertreatment device configured to receive the exhaust gas from the internal combustion engine so that the exhaust gas can be aftertreated by means of the exhaust aftertreatment device. The hybrid vehicle 15 further comprises at least one electrical heater operable to heat the exhaust aftertreatment device. Furthermore, the hybrid vehicle 15 comprises at least one electric machine operable in a generator mode to receive torque to slow the hybrid vehicle 15 and output electrical power. This means, in the generator mode, the electric machine acts as a generator which receives torque provided by the hybrid vehicle 15 moving down the slope. Thus, potential energy of the hybrid vehicle 15 can be regenerated and converted into electrical power by means of the electric machine in the generator mode thereby slowing the hybrid vehicle 15 as it travels down the slope.

The exhaust gas provided by the internal combustion engine can be aftertreatecl by means of the exhaust aftertreatment device particularly efficiently when the exhaust aftertreatrnent device has its light-off teniperature or is above said light-off temperature.

When the internal combustion engine is running and the exhaust gas has a sufficient temperature the exhaust aftertreatment device can be heated by the exhaust gas until the exhaust aftertreatment device reaches the light-off temperature or is above the light-off temperature.

The electric machine is operable in a motor mode in which the electric machine acts as a motor which drives the hybrid vehicle 15 solely or together with the internal combustion engine. For example, the internal combustion engine is switched off when the hybrid vehicle 15 travels down the slope to save fuel. In such a case, the exhaust aftertreatment device can not be heated or kept warm since the internal combustion engine does not provide any exhaust gas. Thus, the hybrid vehicle 15 comprises at least one electrical heater operable to heat the exhaust aftertreatment device. Moreover, the hybrid vehicle comprises at least one energy storage device such as a battery operable to be supplied with and store electrical power from the electric machine in the generator mode.

Moreover, the hybrid vehicle 15 comprises a controller operable in the generator mode to control the electrical heater to heat the exhaust aftertreatment device using electrical power from the electric machine in the generator mode. Thus, the exhaust aftertreatment device can be heated or kept warm when the internal combustion engine does not provide any exhaust gas.

In order to realize a particularly high efficiency of the exhaust aftertreatment device, the controller comprises a prediction module configured to predict at least one parameter indicative of a limitation of the supply of the energy storage device (battery) with electrical power from the electric machine in the generator mode, the limitation possibly occurring during the generator mode, i.e. when the hybrid vehicle 15 travels down the slope. The controller is configured to distribute the electrical power provided by the electrical machine in the generator mode at least among the energy storage device and the electrical heater on the basis of the predicted parameter. Fig. 1 shows a diagram 18 having an ordinate 20 and an abscissa 14, the ordinate 20 showing a heating signal indicative of a state of operation of the electrical heater. In other words, a graph 22 illustrates whether or not the electrical heater is activated. The diagram 18 shows two periods 24 in which the electrical heater is switched off. Moreover, the diagram 18 shows a period 26 in which the electrical heater is switched on thereby heating the exhaust aliertreatment device using electrical power provided by the electrical machine in the generator mode. Thus, the exhaust aftertreatment device is heated by means of the electrical heater in the period 26.

Fig. 1 shows a diagram 28 having an ordinate 30 and an abscissa 14, the ordinate 30 showing the temperature of the exhaust aftertreatment device. A first graph 32 shows the temperature of the exhaust aftertreatment device versus the time in a scenario in which the exhaust aftertreatment device is not heated by means of the electrical heater.

Moreover, a graph 34 shows the temperature of the exhaust afterireatment device versus the time when the exhaust aftertreatment device is heated by the electrical heater.

Fig. 1 shows a point 36 at which the controller starts to charge the battery by means of the electric machine in the generator mode. Fig. 1 further shows a point 38 at which the controller stops charging the battery by means of the electric machine due to a so-called 12t limitation and a limitation with respect to the state of charge saturation of the battery. At a point 40 following the point 38 the electric machine is still in its generator mode since the hybrid vehicle 15 still travels down the slope. However, the electrical power provided by the electric machine in the generator mode is not used to charge the battery, but to operate the electrical heater so that the exhaust aftertreatment device can be heated by means of the electrical heater during the period 26. At a point 42 following the point 40 the controller switches off the electrical heater. Moreover, the generator mode is switched off since the hybrid vehicle 15 has reached the end of the slope at which potential energy of the hybrid vehicle 15 cannot be regenerated by the electric machine.

Fig. 2 shows a diagram 44 having an abscissa 14 and an ordinate 46 showing electric current provided by the electric machine in the generator mode. The diagram 44 shows a first area 48 in which the battery is charged, and a second area 50 in which the exhaust aftertreatment device is heated by the electrical heater. As can be seer from the diagram 44, at first, at least most of the current provided by the electric machine is routed to the battery so as to charge the battery. The current routed to the battery is reduced while the current routed to the electrical heater to heat the exhaust aftertreatment device is increased until at least most of the current provided by the electric machine is routed to the electrical heater.

Fig. 2 shows a diagram 52 having an abscissa 14 and an ordinate 54 showing the melting integral which is also termed by 12t. Moreover, the diagram 52 shows an 12t threshold 56 and a graph 58 illustrating the melting integral versus the time. Moreover, the diagram 52 shows a predicted point 60 of a 12t limitation. Fig. 2 further shows a diagram 62 having an abscissa 14 and an ordinate 64 showing a Soc (state of charge) threshold of the battery.

The diagram 62 shows a graph 66 illustrating the soc threshold versus the time and a predicted point 68 at which soc saturation is reached. Moreover, Fig. 2 shows the diagram 28, wherein the light-off temperature is shown and indicated by 70. Moreover, the diagram 28 in Fig. 2 shows a predicted point 72 at which the temperature of exhaust aftertreatrnent device is below the light-off temperature 70. The points 60, 68 and 72 are predicted by the prediction module and indicative of limitations effecting the supply of the battery with electrical power. By predicting and considering the point 60, 68 and 72 or corresponding parameters the temperature of the exhaust aftertreatment device can be kept at or above the light-off temperature 70 so that a particularly high efficiency of the exhaust aftertreatment device can be realized.

List of reference signs diagram 12 ordinate 14 abscissa hybrid vehicle 16 graph 18 diagram ordinate 22 graph 24 period 26 period 28 diagram ordinate 32 graph 34 graph 36 point 38 point point 42 point 44 diagram 46 ordinate 48 area area 52 diagram 54 ordinate 56 12t threshold 58 graph point 62 diagram 64 ordinate 66 graph 68 point light-oft temperature 72 point A starting point B endpoint

Claims

Claims A hybrid vehicle (15) comprising: -an internal combustion engine operable to output exhaust gas; -an exhaust aftertreatment device configured to receive the exhaust gas from the internal combustion engine; -at least one electrical heater operable to heat the exhaust aftertreatment device; -at least one electric machine operable in a generator mode to receive torque to slow the hybrid vehicle and output electrical power; -at least one energy storage device operable to be supplied with and store electrical power from the electric machine in the generator mode; and -a controller operable in the generator mode to control the electrical heater to heat the exhaust aftertreatment device using electrical power from the electric machine in the generator mode; characterized in that the controller comprises a prediction module configured to predict at least one parameter (60, 68, 72) indicative of a limitation of the supply of the energy storage device with electrical power from the electric machine in the generator mode, the limitation possibly occurring during the generator mode, wherein the controller is configured to distribute the electrical power provided by the electric machine in the generator mode at least among the energy storage device and the electrical heater on the basis of the predicted parameter (60, 68, 72).
2. The hybrid vehicle according to claim 1, characterized in that the parameter (60, 68, 72) comprises an 12t limitation.
3. The hybrid vehicle according to claim 1 or 2, characterized in that the parameter (60, 68, 72) comprises a state of charge saturation of the energy storage device.
4. The hybrid vehicle according to any one of the preceding claims, characterized in that the parameter (60, 68, 72) is predicted on the basis of a route segment on which the hybrid vehicle will possibly travelling, the controller being configured to determine the route segment by means of a navigation system of the hybrid vehicle.
5. A method for operating a hybrid vehicle according to any one of the preceding claims.