Method for operating an onboard network of a hybrid motor vehicle and hybrid motor vehicle

Abstract

A method for operating an onboard network of a hybrid motor vehicle. The onboard network is connected to an energy storage unit, especially a battery; an electric motor of a hybrid drive train, which also has an internal combustion engine; and actuators of an electromechanical chassis system that can be operated as generators. At least one reserve capacity of the energy storage unit is kept open for the supplying of electrical energy generated by at least one portion of the actuators to the onboard network. The reserve capacity being held open is dynamically adapted as a function of at least one item of driver style information describing the driving style of the driver of the hybrid motor vehicle and/or at least one item of situation information describing the current and/or future operation of the hybrid motor vehicle.

Claims

1. A method for operating an onboard network of a hybrid motor vehicle, wherein the onboard network is connected to an energy storage unit, especially a battery; an electric motor of a hybrid drive train, which also has an internal combustion engine; and actuators of an electromechanical chassis system that can be operated as generators, wherein the actuators of the electromechanical chassis system that can be operated as generators are provided to adjust a body of the hybrid motor vehicle with respect to at least one wheel, wherein at least one reserve capacity of the energy storage unit is kept open for receiving electrical energy generated by at least one portion of the actuators to the onboard network so that the at least one portion of the actuators do not over-charge the energy storage unit when generating electrical energy, wherein the reserve capacity being held open is dynamically adapted as a function of at least one item of driver style information describing the driving style of the driver of the hybrid motor vehicle, a user-controlled adjustable operating parameter of the electromechanical chassis system, and at least one item of situation information describing the current and/or future operation of the hybrid motor vehicle, wherein, in order to decrease a state of charge of the energy storage unit and correspondingly increase the at least one reserve capacity, energy is output from the energy storage unit by way of a DC voltage converter to a low-voltage battery provided on a low-voltage network of the hybrid motor vehicle, wherein the at least one item of situation information comprises a roadway quality which describes an expected amount of energy convertible by the electromechanical chassis system and which is determined from environmental information captured by a sensor of the hybrid motor vehicle.

2. The method as claimed in claim 1, wherein capacity of the energy storage unit that is freed up by decreasing the reserve capacity is provided to the electric motor.

3. The method as claimed in claim 1, wherein the situation information used is a road class and/or nature of the roadway of the current and/or future road that is driven on.

4. The method as claimed in claim 3, wherein the road classes used are a city traffic class and/or a highway class and/or a curving country road class and/or a less curving country road class and/or an offroad class, and/or the road class is provided by a navigation system of the hybrid motor vehicle.

5. The method as claimed in claim 1, wherein the situation information is a predictive power feedback demand for the future that is determined as a function of route information describing a future route of the hybrid motor vehicle and provided in particular by a navigation system of the hybrid motor vehicle especially taking into account road classes and/or the nature of roadways along the route.

6. The method as claimed in claim 5, wherein a reserve capacity curve along the route describing the future reserve capacities is determined as a function of the predictive power feedback demand.

7. The method as claimed in claim 6, wherein a predictive state of charge of the energy storage unit and/or a recuperation potential of the electric motor along the route is also determined and taken into account when determining the reserve capacity to be kept open.

8. The method as claimed in claim 7, wherein the predictive power feedback demand is also taken into account during an advanced planning of the operation of the hybrid drive train as a function of the recuperation potential of the electric motor along the route.

9. The method as claimed in claim 1, wherein the driving style information describes the driving style of a current driver in regard to vehicle body movements of the hybrid motor vehicle.

10. The method as claimed in claim 1, wherein a decreasing of the state of charge of the energy storage unit is also brought about when there exists a high recuperation potential on the part of the electric motor.

11. A hybrid motor vehicle, comprising: an onboard network, which is connected to an energy storage unit, especially a battery; an electric motor of a hybrid drive train, which also has an internal combustion engine; and actuators of an electromechanical chassis system that can be operated as generators, wherein the onboard network is associated with an energy management controller of the hybrid motor vehicle, which is designed to carry out a method as claimed in claim 1.

12. The method as claimed in claim 1, wherein the sensor is a camera of the hybrid motor vehicle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further benefits and details of the present invention will emerge from the exemplary embodiments described in the following as well as on the basis of the drawing. Shown therein are:

(2) FIG. 1 a schematic diagram of a hybrid motor vehicle according to the invention, and

(3) FIG. 2 a sketch to explain the method according to the invention.

DETAILED DESCRIPTION

(4) FIG. 1 shows a schematic diagram of a hybrid motor vehicle 1 according to the invention. This vehicle has a hybrid drive train 2, among the components of which are shown an internal combustion engine 3, an electric motor 4 and a transmission 5 in the present case. The electric motor 4, which, of course, can also be operated as a generator for recuperation, is utilized here at a voltage level of 48 V and is connected to a corresponding onboard network 6, in which a rechargeable electrical energy storage unit 7 is present as a battery here.

(5) However, in the present case actuators 9 associated with individual wheels 8 are also connected to the onboard network 6, and the actuators 9 can also be operated as generators. The actuators 9 may be stabilizers, dampers, or the like, and, in particular, they may themselves have an actuator-electric motor. The actuators 9 may be controlled in the resulting active electromechanical chassis system in order to adapt the height of the bodywork to the wheels 8, for example to balance out vibrations, or the like. For example, the electromechanical chassis system may also have a roll stabilizing action.

(6) The onboard network 6, which thus has an overall voltage level of 48 V, is coordinated with an energy management controller 10, which is connected to other vehicle systems and can receive information from them, systems such as a navigation system 11, a driver information system 12, which can provide a driving style information, as well as other vehicle systems 13, which can provide, for example, situation information based on sensor data, especially as regards the nature of the roadway and the section of road up ahead, which can also be predicted from camera data.

(7) Further, the onboard network 6 is connected by way of a d.c. voltage converter 14 to a low-voltage network 15 of the hybrid motor vehicle 1, merely suggested here, which can have, for example, a voltage level of 12 V. The energy management controller 10 is designed to carry out the method of the invention, which shall be explained more closely with the aid of the summary sketch of FIG. 2.

(8) The actual energy management is indicated by a central step 16, which uses various input information, regarding both the hybrid drive train 2 and the electromechanical chassis system or its actuators 9, in order to carry out a unified energy management taking into account both connected systems. Essential input information comes from a prediction, indicated by means of step 17, based on situation information about the road class and the nature of the roadway. In this case, in particular, based on a route provided by the navigation system 11 plus additional information for as long a period as possible in the future, a prediction is made in the present case for the power feedback demand of the actuators 9, the power demand of the actuators 9, a power demand of the electric motor 4, and a recuperation potential of the electric motor 4, especially along the route. It is also possible to infer here the trend of the state of charge of the energy storage unit 7. Additional input information of step 16, concerning, in particular, the electromechanical chassis system, is driving style information 18 about the driving style of the driver, and operating parameters of the electromechanical chassis system, especially an operating mode selected by the user.

(9) It should be noted that a number of additional items of input information may also be called upon, of course, as long as these are useful for the energy management.

(10) Now, the energy management in step 16 also involves, in particular, the determination of a reserve capacity 20 of the energy storage unit 7 that is to be kept free, in order to meet the power feedback demand of the electromechanical chassis system. This means that electrical energy generated by the actuators 9 can basically be accommodated in the onboard network 6, specifically at least partly in the energy storage unit 7. The reserve capacity 20 to be kept open is dynamically adapted, for example, after more power feedback demand is present by the actuators 9 on a curved stretch of road than on a straight, smooth drive, for example, on a highway. If the reserve capacity 20 kept open thus far is released over the course of time, this is provided to the electric motor 4 and thus to the hybrid system. This enables a better utilization of the available capacity of the energy storage unit 7. The determination of the reserve capacity 20 to be kept open also includes, in particular, the driving style information 18 and the operating parameters 19, especially in the form of correction factors.

(11) However, the energy management of step 16 goes far beyond a dynamic variation of the power feedback reserve, i.e., the reserve capacity 20 to be kept open. The power feedback demand of the actuators 9 is also taken into account in regard to determining an operating strategy for the hybrid drive train 2, together with the recuperation potential of the electric motor 4, especially in order to keep the fuel consumption by the internal combustion engine 3 as low as possible, so that energy predictively fed back from the actuators 9 can also be used as much as possible. Not only an operation of the electric motor 4, as indicated in step 21, can be considered as a way of removing electrical energy from the onboard network 6, but also it is possible in the context of the present invention to create the reserve capacity 20 to be kept open or to consume the immediately generated energy of the actuators 9 or even, in order to use the recuperation potential of the electric motor 4, as indicated in step 22, to shift electrical energy by way of the d.c. voltage converter 14 from the onboard network 6 to the low-voltage network 15, for example, in order to charge a low-voltage battery there.

(12) In particular, due to the interlinked energy management with simultaneous consideration of the electromechanical chassis system and the hybrid system, a significant improvement results in the energy budget, so that, in other words, it can be said that an overarching energy optimization of the efficiency is made possible by the interlinking of the power feedback demand of the electromechanical chassis system as a function of the road and driver profiles or the nature of the roadway with the operating strategy of the hybrid system.

(13) It should be further pointed out here that already known concepts or algorithms may also basically be applied, at least for hybrid systems as such, in the context of the present invention, for predicting the recuperation of the electromechanical chassis system. By analogy with the electric motor 4 and its recuperation, certain sections of road can be assigned mean regeneration rates, for example, given a knowledge of their properties, and these can then be adapted with correction factors depending on the driving style information, or the like. In the context of their use for determining an operating strategy for the hybrid drive train 2, power feedback demands determined for the electromechanical chassis system can ultimately be added to the power feedback potential of the electric motor 4, possibly with additional consideration of the consumption of the actuators 9 or the electric motor 4. In this way, using known knowledge, a specific implementing of the approaches of the invention is possible.