Hybrid vehicle and method for adapting a power limitation of an internal combustion engine

Abstract

A vehicle and method for controlling a vehicle having a traction battery and an internal combustion engine include adapting a power limitation of the internal combustion engine by sensing a currently supplied power level of the internal combustion engine and a current velocity of the vehicle, sensing an ambient temperature of the vehicle and determining an associated ambient-temperature-related weighting factor, sensing an ambient air pressure and determining an associated air-pressure-related weighting factor, determining a thermal load indicator as a function of a ratio of the sensed currently supplied power and the sensed current velocity as well as of the ambient-temperature-related weighting factor, the air-pressure-related weighting factor, and a vehicle-bodywork-related weighting factor, and limiting a maximum supplied power level of the internal combustion engine as a function of the determined thermal load indicator.

Claims

1. A method of controlling a vehicle having an internal combustion engine, a traction battery, and an electric machine configured to propel the vehicle, the method comprising: sensing a currently supplied power level of the internal combustion engine and a current velocity of the vehicle; sensing an ambient temperature and determining, by a vehicle controller, an associated ambient-temperature-related weighting factor; sensing an ambient air pressure of the vehicle and determining, by the vehicle controller, an associated air-pressure-related weighting factor; determining, by the vehicle controller, a thermal load indicator based on the sensed currently supplied power level, current vehicle velocity, the ambient-temperature-related weighting factor, the air-pressure-related weighting factor, and a vehicle-bodywork-related weighting factor; and limiting, by the vehicle controller, a maximum supplied power level of the internal combustion engine based on the thermal load indicator wherein the thermal load indicator is determined by a ratio of the currently supplied power level and the current velocity of the vehicle multiplied by the ambient-temperature-related weighting factor, the air-pressure-related weighting factor, and the vehicle-bodywork-related weighting factor.

2. The method of claim 1 wherein, when the current velocity (V) of the vehicle exceeds a vehicle velocity threshold, determining the ratio comprises determining the ratio (R) according to R=P.sup.K1/(V−K2), where P represents the currently supplied power level of the internal combustion engine, K1 is a first constant factor in a range between 1 and 2, and K2 is a second constant factor higher than zero and lower than the vehicle velocity threshold.

3. The method of claim 2, wherein determining the ratio (R) comprises determining R according to R=P.sup.K1/(MAX(V, V.sub.th)−K2), where MAX selects the maximum of the vehicle velocity V and the vehicle velocity threshold V.sub.th.

4. The method of claim 3 wherein the first constant factor K1=1.6.

5. The method of claim 3 wherein the second constant factor K2=15 kilometers per hour.

6. The method of claim 2 wherein determining the ambient-temperature-related weighting factor (G.sub.t) comprises determining G.sub.t=((T.sub.env+40)/K3).sup.2, wherein T.sub.env is the ambient temperature in degrees Celsius, and K3 is a third constant factor which is greater than 60 and lower than 80.

7. The method of claim 6 wherein the third constant factor K3=70.

8. The method of claim 6 wherein determining the air-pressure-related weighting factor (G.sub.p) comprises determining G.sub.p=K4/Pr.sub.env, wherein Pr.sub.env is the ambient air pressure in millibars, and K4 is a fourth constant factor which is greater than 900 and less than 1100.

9. The method of claim 1 wherein the vehicle-bodywork-related weighting factor depends on a surface area of a front portion of the vehicle.

10. The method of claim 9 wherein the vehicle-bodywork-related weighting factor corresponds to 1/A, where A is a constant between 1 to 10 specified in square meters.

11. The method of claim 1 wherein determining the thermal load indicator comprises mean value filtering during which the thermal load indicator is filtered by sliding averaging over a time window.

12. The method of claim 1 further comprising limiting electrical power supplied by the electric machine based on the thermal load indicator.

13. A vehicle comprising: an internal combustion engine; an electric machine mechanically coupled to the internal combustion engine; a traction battery electrically connected to the electric machine; and a controller configured to limit a maximum supplied power level of the internal combustion engine in response to a thermal load indicator calculated by the controller, the thermal load indicator corresponding to a ratio of a currently supplied power level of the internal combustion engine and current vehicle velocity multiplied by: an ambient temperature related weighting factor, an ambient air pressure related weighting factor, and a weighting factor associated with surface area of a front portion of the vehicle.

14. The vehicle of claim 13 wherein the controller is further configured to limit electric power supplied by the electric machine based on the thermal load indicator.

15. The vehicle of claim 14 wherein, in response to the current vehicle velocity exceeding a vehicle velocity threshold (V.sub.th), the controller calculates the thermal load indicator according to a ratio (R) where R=P.sup.K1(V−K2), where P represents the currently supplied power level of the internal combustion engine, K1 is a first constant factor in a range between 1 and 2, and K2 is a second constant factor higher than zero and lower than the vehicle velocity threshold.

16. The vehicle of claim 14 wherein the controller is further configured to calculate the ratio (R) according to R=P.sup.K1/(MAX(V, V.sub.th)−K2), where MAX selects the maximum of the current vehicle velocity V and a vehicle velocity threshold V.sub.th, and K2 is a constant factor higher than zero and lower than V.sub.th.

17. A vehicle comprising: an internal combustion engine; an electric machine mechanically coupled to the internal combustion engine and configured to selectively propel the vehicle; an ambient temperature sensor; an ambient air pressure sensor; a vehicle velocity sensor; a traction battery electrically connected to the electric machine; and a controller receiving signals from the ambient temperature sensor, the ambient air pressure sensor, and the vehicle velocity sensor, the controller configured to limit a maximum supplied power level of the internal combustion engine and to limit a maximum supplied electrical power from the electric machine in response to a thermal load indicator (STC) calculated by the controller, the thermal load indicator based on a ratio of a currently supplied power level of the internal combustion engine to a current velocity of the vehicle multiplied by: an ambient-temperature-related weighting factor, an ambient-air-pressure-related weighting factor, and a vehicle-bodywork-related weighting factor, the vehicle-bodywork-related weighting factor based on surface area of a front portion of the vehicle.

18. The vehicle of claim 17 wherein the controller is configured to calculate the ratio (R) according to: R=P.sup.K1/(V−K2), where P represents the currently supplied power level of the internal combustion engine, V represents the current velocity of the vehicle, K1 is a first constant factor in a range between 1 and 2, and K2 is a second constant factor higher than zero and lower than a vehicle velocity threshold.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic illustrating operation of a system or method for adapting a power limitation of an internal combustion engine of a hybrid vehicle according to embodiments of the disclosure.

(2) FIG. 2 shows a schematic illustrating a representative hybrid vehicle having an internal combustion engine with power limitation according embodiments of the disclosure.

DETAILED DESCRIPTION

(3) As required, detailed embodiments are disclosed herein; however, it is to be understood that the disclosed embodiments are merely representative and 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 particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the claimed subject matter.

(4) Of course, other embodiments can be used and structural or logical amendments can be performed without deviating from the claimed subject matter. Of course, the features of the various embodiments which are described above and below can be combined with one another unless specifically stated otherwise. The description is therefore not to be interpreted in a restrictive sense, and the scope of protection is defined by the appended claims.

(5) FIG. 1 shows a schematic illustration of operation of an example system or method for adapting a power limitation of an internal combustion engine of a hybrid vehicle according to the disclosure. In the embodiment shown, the method 100 comprises, after a starting state 101, sensing 102 of a currently supplied power level of the internal combustion engine P of the hybrid vehicle, and sensing 103 of a current velocity V of the hybrid vehicle. Furthermore, sensing 104 of an ambient temperature T.sub.env of the hybrid vehicle and determining 105 an associated ambient-temperature-related weighting factor G.sub.t. In addition, sensing 106 of an air pressure Pr.sub.env in the surroundings of the hybrid vehicle, and determining 107 an associated air-pressure-related weighting factor G.sub.p.

(6) This is followed by determination 108 of a ratio R.sub.pv of the sensed currently supplied power P and of the sensed current velocity V. Furthermore, a vehicle-bodywork-related weighting factor G.sub.k is determined 109, wherein G.sub.k is a constant which is predefined by the design of the hybrid vehicle so that the determination can also comprise reading in G.sub.k from a memory.

(7) On this basis, a thermal load indicator STC is determined 110 as a function of the ratio R.sub.pv of the sensed currently supplied power level P and the sensed current velocity V as well as of the ambient-temperature-related weighting factor G.sub.t, the air-pressure-related weighting factor G.sub.p and additionally of the vehicle-bodywork-related weighting factor G.sub.k. A maximum supplied power level P.sub.max of the internal combustion engine is then limited 111 as a function of the determined thermal load indicator STC.

(8) In the embodiment shown, the thermal load indicator is determined 110 as STC=R.sub.pv*G.sub.k*G.sub.t*G.sub.p, i.e. as the ratio R.sub.pv of the sensed currently supplied power level P and of the sensed current velocity V weighted with the product of the ambient-temperature-related weighting factor G.sub.t, of the air-pressure-related weighting factor G.sub.p and of the vehicle-bodywork-related weighting factor G.sub.k. In this context, the ratio R.sub.pv is determined as R.sub.pv=P.sup.K1/(V−K2) where K1=1.6 and K2=15 km/h, or in a preferred embodiment as R.sub.pv=P.sup.k1/(MAX(V, V.sub.th)−K2) where K1=1.6, V.sub.th=17 km/h and K2=15 km/h. The vehicle-bodywork-related weighting factor G.sub.k is determined as G.sub.k=1/A, where A represents a surface of a front area of the hybrid vehicle specified in square meters, and is selected from a range from 1 to 10 depending on the design of the vehicle. The ambient-temperature-related weighting factor G.sub.t is determined as G.sub.t=((T.sub.env+40)/K3).sup.2, wherein T.sub.env is the ambient temperature (in degrees Celsius) and K3=70, and the air-pressure-related weighting factor G.sub.p is determined as G.sub.p=K4/Pr.sub.env, wherein Pr.sub.env is the air pressure in the surroundings of the hybrid vehicle in millibars, and K4=995 (in millibars). In the embodiment shown, the temperature load indicator is therefore determined as

(9) $\mathrm{STC}=\frac{P^{1.6}}{V-15}*\frac{1}{A}*{\left(\frac{T_{\mathrm{env}}+40}{70}\right)}^2*\frac{995}{P{r}_{env}}$
with numerical data which correspond to P in kilowatts, V in kilometers per hour, A in square meters, T.sub.env in degrees Celsius and Pr.sub.env in millibars,

(10) In order to filter large changes in the thermal load indicator STC, the determination 110 of the thermal load indicator STC in the embodiment shown also includes filtering the thermal load indicator by sliding averaging over a time window. The time window has here, for example, a length of 180 seconds.

(11) In the embodiment shown, after the sensing 102 of the currently supplied power level P, the currently supplied power level P of the internal combustion engine is additionally limited 112 as a function of a permitted upper limiting value for the current velocity V of the hybrid vehicle. The permitted upper limiting value is determined here, for example, by the maximum thermal loadbearing capacity of the hybrid vehicle or an integral component thereof, but can also be determined e.g. by the maximum permissible speed, possibly lower than the latter, for the road being traveled on.

(12) In addition to limiting 111 the maximum supplied power level P.sub.max of the internal combustion engine, in the embodiment shown, limiting 113 of an electrical power level supplied by means of a generator, operated by the internal combustion engine of the hybrid vehicle, is also provided.

(13) In the embodiment shown of the method, there is additionally provision not only to limit the maximum supplied power level P.sub.max as a function of the determined thermal load indicator STC but also to carry out sensing 114 of a coolant temperature of the hybrid vehicle and limiting 115 of the maximum supplied power level of the internal combustion engine also as a function of the sensed coolant temperature, and sensing 116 of a torque of the internal combustion engine and limiting 117 of the maximum supplied power level of the internal combustion engine, also as a function of the sensed torque.

(14) After the limiting 111 of the maximum supplied power level and the limitation of the supplied electrical power level 113, the method ends in a final state 118, wherein as a rule the method is immediately re-started while the hybrid vehicle is operating, and therefore continuous adaptation and/or calibration of the maximum supplied power level to the possibly changing operating circumstances are/is implemented.

(15) FIG. 2 shows a schematic illustration of an example of a hybrid vehicle according to one or more embodiments. The hybrid vehicle 200 has an accumulator 201 and an electric motor 202 which is connected to the accumulator 201 and is configured to drive the hybrid vehicle 200. In addition, the hybrid vehicle 200 comprises a generator 203 which is connected to the accumulator 201, and an internal combustion engine 204 which is connected at least to the generator 203 and is at least configured to drive the generator 203 in order to charge the accumulator 201.

(16) Furthermore, the hybrid vehicle 200 has a multiplicity of sensors 205, 206, 207, 208, The first sensor 205, i.e. the first sensor unit, is configured to sense a currently supplied power level P of the internal combustion engine 204. The second sensor 206 is configured to sense a current velocity V of the hybrid vehicle 200. The third sensor 207 is configured to sense an ambient temperature T.sub.env of the hybrid vehicle 200, and the fourth sensor 208 is configured to sense an air pressure Pr.sub.env in the surroundings of the hybrid vehicle 200.

(17) In addition, the hybrid vehicle 200 has an electronic control unit 209 which is directly or indirectly communicatively connected, for example via an on-board network, to the sensors 205, 206, 207, 208 and the further vehicle components. The electronic control unit 209 is configured to carry out a method according to the first aspect of the invention. In this context, the steps of the method are carried out either by the electronic control unit 209 itself or are controlled by other components of the hybrid vehicle 200 to carry out the respective step. For this purpose, the electronic control unit 209 is configured as a programmable device at least with a memory 210 and a processor 211, wherein pieces of code are stored in the memory 210 and when they are loaded and executed by the processor 211 cause the electronic control unit 209 to carry out the control of the vehicle.

(18) Of course, even though method steps are described in accordance with a certain ordered sequence, they could be carried out to a certain extent in a sequence other than that described. It also goes without saying that certain steps can be carried out once or repeatedly at the same time or successively, that other steps could be added or that certain steps, described here, could be omitted. In other words, the present descriptions are made available for the purpose of illustrating specific embodiments and should not be interpreted as limiting the disclosed subject matter. Similarly, while illustrated or described with respect to a single controller, various steps or functions may be distributed among multiple vehicle controllers in communication over a vehicle network.

(19) The figures are not necessarily accurate in every detail and true to scale and could be illustrated in an enlarged or reduced fashion in order to provide a better overview. Therefore, functional details which are disclosed here are not to be understood in a limiting fashion but rather as an illustrative basis which provides a person skilled in the art in this field of technology with guidance as to how to use the present invention in a variety of ways.

(20) The expression “and/or” used here means, when employed in a series of two or more elements, that each of the specified elements can be used alone, or any combination of two or more of the specified elements can be used. If, for example, there is a description of a combination which contains the components A, B and/or C, the combination can contain A alone, B alone, C alone, A and B in combination, A and C in combination, B and C in combination or A, B and C in combination.

(21) Although various embodiments have been illustrated and described in detail, the claimed subject matter is not limited by the disclosed examples and other variations may be derived therefrom by a person skilled in the art without departing from the scope of the claimed subject matter.

(22) While representative embodiments are described above, it is not intended that these embodiments describe all possible forms of the claimed subject matter. The words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the claimed subject matter. Additionally, the features of various implementing embodiments may be combined to form further embodiments that may not be explicitly illustrated or described.