DE102015202644A1 - Method and device for operating a hybrid vehicle - Google Patents

Abstract

The invention relates to a method and an apparatus for operating a hybrid vehicle comprising an electric machine and an internal combustion engine, wherein at least one mode is provided in which at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the internal combustion engine is operated.

Description

State of the art

There are motor vehicles are known which comprise an internal combustion engine and an electric motor, both motors contribute directly or indirectly to the propulsion of the motor vehicle. Such vehicles are referred to as hybrid vehicles. Depending on the design of the hybrid vehicle, both the engine and the electric motor may be used to contribute torque to the powertrain of the vehicle. However, hybrid vehicles are also known in which the internal combustion engine is used exclusively to drive a generator, which in turn charges a battery and thus provides electrical energy for the electric motor. Depending on the chosen operating strategy, hybrid vehicles can either be driven by the electric motor or by the internal combustion engine, or at least temporarily only the internal combustion engine or only the electric motor is used to propel the vehicle. The electric motor can be both motor and generator, so for charging the battery while driving, operated.

In order to decide which operating strategy is to be used, so-called cost functions are considered which, depending on a required torque, a given speed and other input variables, indicate fictitious costs which arise for a given period for a certain power distribution between the two motors. In order to determine the most favorable operating mode or power distribution for a given time, the minimum of the cost function is determined and the power distribution belonging to this minimum is selected. The cost function takes into account significant variables such as engine torque and speed-dependent efficiencies.

It is also known, during operation of a vehicle which has only one internal combustion engine, one or more cylinders at least temporarily not operate. The remaining cylinders can thereby be operated at a more favorable load point, which reduces the consumption of the internal combustion engine. In addition to switching off individual cylinders shutdown of whole cylinder banks is known.

Disclosure of the invention

The inventive method and the device according to the invention have the advantage that when operating a hybrid vehicle comprising an electric machine and an internal combustion engine, at least one mode is provided in which at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the Internal combustion engine is operated. As a result, the fuel-saving potential of a hybrid drive can be connected to that of a cylinder deactivation. Thus, further fuel savings can be realized.

It is advantageous to select a desired operating mode from a first to fourth operating mode, the first operating mode comprising operating all the cylinders of the internal combustion engine and operating the electric machine in an engine operation, the second operating mode operating all cylinders of the internal combustion engine and the electric machine is operated in a generator mode, the third mode includes that at least one cylinder of the internal combustion engine is not operated while at least one further cylinder of the internal combustion engine is operated and the electric machine is operated in a motor mode, and the fourth mode includes in that at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the internal combustion engine is operated and the electric machine is operated in a generator mode. This ensures that all possible operating modes are taken into account in the determination of a desired operating mode, which are given by the different use of the electric machine in motor and generator operation and the possibility of switching off at least one cylinder.

It is also advantageous if the desired operating mode of the hybrid vehicle is selected as a function of at least one cost function. Under cost function is a function to understand that indicates costs depending on consumption-related input variables such as torque and / or speed and possibly a state of charge of a battery incurred during operation of the electric machine and the internal combustion engine. Costs may be understood to mean a quantity that attempts to represent the actual monetary costs of a vehicle operation. However, costs can also be understood to mean a quantity which correlates with a fuel expenditure and, for example, has the dimension of a service. In a preferred embodiment of the invention, a cost function is composed additively of a first and a second term, the first term representing the cost of the operation of the electric machine and the second term the cost of operating the internal combustion engine. In a preferred embodiment, the first and the second term are dependent on a power to be retrieved from the electric machine or the Combustion engine. In this way, a power distribution between the electric machine and the internal combustion engine can be optimized. In an alternative embodiment, the first and the second term are dependent on a torque that is provided by the electric machine or the internal combustion engine.

It is particularly advantageous to select the desired operating mode as a function of a first to fourth cost function, wherein the first cost function represents the first operating mode, the second cost function represents the second operating mode, the third cost function represents the third operating mode, and the fourth cost function represents the fourth operating mode. This ensures that when selecting the desired operating mode, the potential savings of all possible operating modes can be determined and compared cleanly.

It is advantageous to select the desired operating mode as a function of minimizing at least one cost function.

It is particularly advantageous if the desired operating mode is selected as a function of minimizations of the first to fourth cost function. Thus, it is possible for each of the available operating modes to determine the specific costs that would be incurred in selecting the respective operating mode with the most favorable power distribution between the electric machine and the internal combustion engine.

It is particularly advantageous to select the operating mode as the desired operating mode, whose representative cost function has the lowest value of the minimized first to fourth cost function. Thus, the operating mode is selected whose cost function has the lowest value of all considered cost functions at the location of a previously determined minimum. For this, it is preferred to first minimize the first to fourth cost functions independently of each other, i. In each case, the minimum of the first to fourth cost function is determined and the value of the first to fourth cost function determined at the location of the respectively determined minimum. Thus, it is ensured that not only the most fuel-efficient operating mode is selected, but in addition also the most fuel-efficient within the desired operating mode power distribution between the electric machine and the internal combustion engine is determined.

It is advantageous if the desired operating mode is selected exclusively from the first or second operating mode and the third and fourth cost function are not minimized if at least one cylinder deactivation condition is present. Thus, computing power of an electronic control unit can be saved, since the number of cost functions to be minimized is reduced if there are conditions that preclude operation of the internal combustion engine with shutdown of individual cylinders. Such conditions are referred to as cylinder deactivation conditions. Cylinder shut-off conditions and their determination are known in the art.

In an advantageous embodiment, the selection of the desired operating mode is performed again at regular intervals. In a particularly advantageous embodiment, the desired operating mode is determined every 10 ms in accordance with the invention.

It is advantageous to provide a fifth mode, in which the electric machine is operated by a motor, while the internal combustion engine is not operated.

Also advantageous are a device which is set up to carry out the method according to the invention and a computer program which is designed or is designed by compiling to carry out each step of the method according to the invention.

Also advantageous are an electronic storage medium, on which said computer program is stored, and an electronic control unit, which comprises said storage medium.

The inventive method and the device according to the invention are not limited to hybrid vehicles with exactly one internal combustion engine and one electric machine. In an advantageous development, it is rather provided that in a hybrid vehicle which has a plurality of electrical machines and / or a plurality of internal combustion engines, two cost functions are considered for each electrical machine and each internal combustion engine. In electrical machines that are operated either exclusively as a generator or exclusively by motor, as well as in internal combustion engines in which all cylinders are always operated during operation, only one cost function is provided in each case.

Hereinafter, an embodiment of the present invention will be explained in more detail with reference to the accompanying drawings. Showing:

Short description of the drawing

1 a schematic representation of a vehicle with a device for carrying out the method according to the invention.

Embodiments of the invention

1 shows a schematic representation of a vehicle with an apparatus for performing the method according to the invention. A hybrid vehicle ( 2 ), which has an internal combustion engine ( 4 ) and an electric machine ( 6 ), an electronic control unit ( 10 ) and a battery ( 8th ), wherein the battery is connected to the electric machine ( 6 ), that it can be charged by the latter when the electric machine ( 6 ) is operated in a regenerative operation. The battery ( 8th ) supplies the electric machine ( 6 ) with energy when the electric machine ( 6 ) is operated in a motorized operation. The internal combustion engine ( 4 ) is arranged such that at least one cylinder of the internal combustion engine is temporarily not operated, while at least one further cylinder of the internal combustion engine ( 4 ) is operated. The electronic control unit ( 10 ) comprises an electronic storage medium ( 15 ).

The hybrid vehicle ( 2 ) further comprises a first speed sensor ( 20 ), which is a speed of the internal combustion engine ( 4 ) signal to the electrical control unit ( 10 ) and a second speed sensor ( 21 ), which represents a signal representing the rotational speed of the electrical machine to the control unit ( 10 ) transmitted. A torque detection module ( 22 ) detects a target torque and transmits a signal representing the target torque to the electronic control unit ( 10 ). The setpoint torque can be determined, for example, from an accelerator pedal position or from torque coordination of the control unit ( 10 ) of the vehicle. the torque detection module ( 22 ) can be part of the electronic control unit ( 10 ) be.

The hybrid vehicle ( 2 ) further comprises a temperature sensor ( 24 ), which determines the temperature of the battery ( 8th ) and a corresponding signal to the electronic control unit ( 2 ) transmitted. A charge state detection unit ( 28 ) determines the state of charge of the battery ( 8th ) and transmits a corresponding signal to the electronic control unit ( 10 ). In the charge state detection unit ( 28 ) may be a sensor or an electronic control unit ( 10 ) integrated module act.

The electronic control unit ( 10 ) includes a mode coordination module ( 30 ), four minimization modules ( 40 . 41 . 42 . 43 ), a comparison module ( 50 ) as well as a mode conversion module ( 60 ), which in turn is a cylinder deactivation module ( 62 ). The electronic control unit ( 10 ) further comprises a release module ( 70 ), which is arranged to determine whether a shutdown of at least one cylinder of the internal combustion engine ( 4 ) is permitted at a given time. For this purpose, the release module determines whether cylinder deactivation conditions are met and transmits an exclusion signal to the mode coordination module in the presence of cylinder deactivation conditions ( 30 ). The release module ( 70 ) as well as its mode of action are known to the person skilled in the art and will not be further described.

In the context of the method according to the invention, the operating mode coordination module ( 30 ) in a first step, a current speed of the internal combustion engine ( 4 ), a current speed of the electric machine ( 6 ) a current state of charge of the battery ( 8th ), a current temperature of the battery ( 8th ) as well as the current setpoint torque.

In a second step, the operating mode coordination module ( 30 ) is checked by the release module ( 70 ) an exclusion signal is provided. If no exclusion signal is provided, a first cost function is sent to the first minimization module ( 40 ) transfer. The first cost function can be the following function: K_ges = P_VM / eta_VM (Tq, n) + k_E (SOC) · P_EM / (eta_E (Tq, n) · eta_Batt (I, SOC, T)), where K_ges indicates the cost. P_VM the power of the internal combustion engine ( 4 ), eta_VM (Tq, n) the efficiency of the internal combustion engine ( 4 ) is referred to as a function of torque and rotational speed, k_E (SOC) designates a battery cost factor that depends on the state of charge of the battery ( 8th ), which can be determined experimentally, for example. P_EM denotes the power of the electrical machine ( 6 ), eta_E (Tq, n) denotes the efficiency of the electric machine ( 6 ) as a function of torque and speed and eta_Batt (I, SOC, T) denotes the efficiency of the battery ( 8th ) as a function of the battery current (I), the charge state (SOC) and the battery temperature (T). The battery current is the expected battery current, which results in operation of the electric machine with a given power. The first cost function represents a first mode in which the electric machine ( 6 ) is operated by a motor and all cylinders of the internal combustion engine ( 4 ) operate.

In the second step, a second cost function is also sent to the second minimization module ( 41 ) transmitted. The second cost function represents a second mode in which the electric machine ( 6 ) is operated as a generator and all cylinders of the internal combustion engine ( 4 ) operate. The second cost function can be the following function: K_ges = P_VM / eta_VM (Tq, n) + k_E (SOC) · P_EM · eta_E (Tq, n) · eta_Batt (I, SOC, T)

In the second step, a third cost function is also sent to the third minimization unit ( 42 ) transmitted. The third cost function can be the following function: K_ges = P_VM_ZAS / eta_VM_ZAS (Tq, n) + k_E (SOC) · P_EM / (eta_E (Tq, n) · eta_Batt (I, SOC, T)), where P_VM_ZAS is the power of the internal combustion engine ( 4 ) and eta_VM_ZAS the efficiency of the internal combustion engine ( 4 ) in the third mode. In the third mode, the electric machine ( 6 ) operated by a motor. In the third operating mode, at least one cylinder of the internal combustion engine ( 4 ), while at least one further cylinder of the internal combustion engine ( 4 ) is operated. The third operating mode is therefore a so-called cylinder deactivation or a so-called half-engine operation.

In the second step, a fourth cost function is also sent to the fourth minimization module ( 43 ) transmitted. The fourth cost function can be the following function: K_ges = P_VM_ZAS / eta_VM_ZAS (Tq, n) + k_E (SOC) * P_EM * eta_E (Tq, n) * eta_Batt (I, OC, T).

In the fourth mode, the electric machine ( 6 ) operated as a generator. In the fourth operating mode, at least one cylinder of the internal combustion engine ( 4 ), while at least one further cylinder of the internal combustion engine ( 4 ) is operated. The fourth operating mode is therefore a so-called cylinder deactivation or a so-called half-engine operation.

In a third step, minimize the minimization modules ( 40 . 41 . 42 . 42 ) in each case the cost function transmitted to them, ie the minimization modules vary a power distribution between electrical machine ( 6 ) and internal combustion engine ( 4 ) and determine the power distribution at which the cost function has its minimum. Thus, an optimal power distribution is determined under cost aspects. The thus optimized power distributions, together with the corresponding minimum cost values, are sent to the comparison module ( 50 ) transmitted.

In a fourth step, the comparison module selects the lowest value from all the minimum cost values received by comparison and transmits this, together with the associated power distribution, to the conversion module ( 60 ). To the implementation module ( 60 ) is also transmitted information about which cost function or mode belongs to the transmitted power distribution. The corresponding operating mode corresponds to a desired operating mode and is then used by the conversion module ( 62 ) with the previously determined power distribution between electrical machine ( 6 ) and internal combustion engine ( 4 ) implemented in a fifth step. The implementation module ( 60 ), in the implementation of the third and / or fourth mode debouncing time, for example, 0.5 to 2 seconds. The third or fourth operating mode is thus implemented only if only the third and / or fourth operating mode has been selected during the last debouncing time. Thus, only short-term and therefore low-consumption uses of the third and fourth modes can be avoided.

If the desired operating mode is either the third or fourth operating mode and if the first or second operating mode was not selected during the debouncing time, the deactivation of the at least one cylinder by a cylinder deactivation module ( 62 ), the part of the implementation module ( 60 ).

If an exclusion signal is present at the beginning of the second step, in the second step only the first cost function is sent to the first minimization module ( 40 ) and the second cost function to the second minimization module ( 41 ) transmitted. The minimization modules ( 40 . 41 . 42 . 43 ) are set up in such a way that they remain idle in the third step, if in the second step no cost function is transmitted to them. The idle minimization modules ( 40 . 41 . 42 . 43 ) transmit artificially elevated minimum cost values to the comparison module. The minimum cost values of the idle minimization modules ( 40 . 41 . 42 . 43 ) so high that a selection by the comparison module ( 50 ) is excluded in the fourth step.

At regular intervals, preferably every 10 ms, the process is repeated by performing the first step.

The method according to the invention is also suitable for easily transporting the hybrid vehicle ( 2 ) either only by means of an electric machine ( 6 ) or only by internal combustion engine ( 4 ) to drive. If a minimization of a cost function results in a minimum in a power distribution that exclusively delivers power by either the internal combustion engine ( 4 ) or the electric machine ( 6 ), only the internal combustion engine ( 4 ) or only the electric machine ( 6 ) from the implementation module ( 60 ).

Claims (12)

Method for operating a hybrid vehicle comprising an electric machine and an internal combustion engine, characterized in that at least one mode is provided, wherein at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the internal combustion engine is operated. A method according to claim 1, characterized in that a desired mode is selected from a first to fourth mode, wherein • the first mode comprises operating all the cylinders of the internal combustion engine and operating the electric machine in a motor mode, • the second mode of operation in that all the cylinders of the internal combustion engine are operated and the electric machine is operated in a generator mode, the third operating mode comprises that at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the internal combustion engine is operated and the electric machine in one operating mode, and • the fourth operating mode comprises that at least one cylinder of the internal combustion engine is not operated, while at least one further cylinder of the internal combustion engine is operated and the electric machine in a regenerative operation is operated. A method according to claim 2, characterized in that the desired operating mode of the hybrid vehicle is selected depending on at least one cost function. A method according to claim 2 or 3, characterized in that the target mode is selected in response to a first to fourth cost function, wherein the first cost function represents the first mode, the second cost function represents the second mode, the third cost function represents the third mode and the fourth Cost function represents the fourth mode. A method according to claim 3, characterized in that the desired operating mode is selected depending on a minimization of at least one cost function. A method according to claim 4, characterized in that the desired operating mode is selected as a function of minimizations of each of the first to fourth cost function. A method according to claim 6, characterized in that the operating mode is selected as the desired operating mode, the representing cost function having the lowest value of the minimized first to fourth cost function. A method according to claim 6 or 7, characterized in that the target mode is selected exclusively from the first or second mode and the third and fourth cost functions are not minimized when at least one cylinder deactivation condition is present. Apparatus adapted to carry out the method according to one of the preceding claims. A computer program adapted or compiled to perform each step of the method of any one of the preceding claims. An electronic storage medium storing the computer program of claim 10. An electronic control unit comprising the electronic storage medium of claim 11.

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