DE102016206814A1 - Method and device for operating a motor vehicle - Google Patents

Abstract

The invention relates to a method for operating a motor vehicle (1), comprising the following steps: detecting a driving intention for the motor vehicle (1) predetermined by a driver; Determining an adaptation variable (AF) as a function of a total vehicle weight (m) and / or a road gradient; - Determining a drive motor torque (M) depending on the adaptation variable (AF) and the Vortriebwunsches, - Operating a drive motor (2) of the motor vehicle (1) depending on the drive motor torque (M).

Description

Technical area

The invention relates to motor vehicles with a drive motor for providing a drive torque, and more particularly to methods for efficiently operating the motor vehicle depending on an actuation of an operating device by a driver to specify a propulsion request.

Technical background

In particular, in commercial vehicles, the total vehicle weight may differ significantly due to the payload. This is usually noticeable to a driver in that the accelerator pedal must be actuated to varying degrees in order to achieve a desired propulsion of the motor vehicle, for. B. a desired vehicle acceleration to achieve. The propulsion of the motor vehicle is dependent on various influences. In addition to the payload, which determines the total weight, in particular, the road inclination has an influence on the achievable upon actuation of the accelerator pedal vehicle acceleration.

If the road inclination or the payload changes, the driver usually only has to get a feel for what acceleration of the vehicle can be achieved at which accelerator pedal position through some time of driving. This can cause the accelerator pedal is not operated in an optimal manner and thereby the energy consumption, such. As the fuel consumption is higher than if the driver from the outset would know the optimal accelerator pedal position in the current load condition and road gradient.

Disclosure of the invention

According to the invention, a method for operating a motor vehicle according to claim 1 and a device and a motor vehicle according to the independent claims are provided.

Further embodiments are specified in the dependent claims.

• – Erfassen eines von einem Fahrer vorgegebenen Vortriebswunsch für das Kraftfahrzeug;
• – Bestimmen einer Anpassungsgröße abhängig von einem Fahrzeuggesamtgewicht und/oder einer Fahrbahnneigung;
• – Ermitteln eines Antriebsmotormoment abhängig von der Anpassungsgröße und dem Vortriebswunsch; und
• – Betreiben eines Antriebsmotors des Kraftfahrzeugs abhängig von dem Antriebsmotormoment.

According to a first aspect, a method for operating a motor vehicle is provided, with the following steps:

• Detecting a propulsion request for the motor vehicle specified by a driver;
• Determining an adaptation variable as a function of a total vehicle weight and / or a road gradient;
• - Determining a drive motor torque depending on the adaptation size and the propulsion desired; and
• - Operating a drive motor of the motor vehicle depending on the drive motor torque.

One idea of the above method is, in the implementation of a z. B. by an operation of a driving control device such. B. an accelerator pedal, required propulsion request to consider the total vehicle weight and the road gradient and only to drive the drive motor so that the torque is sufficient to provide the propulsion desired vehicle acceleration. Thus, the torque to be provided by the drive motor should be adapted to the total vehicle weight and the roadway inclination so that the driver intuitively achieves the desired vehicle acceleration upon actuation of the driving control device to specify a desired propulsion request, regardless of the actual total vehicle weight and the roadway inclination.

Furthermore, the realization of the above function enables a simple implementation in an engine control unit taking into account the vehicle state variables already existing there or determined by an algorithm, such as the total vehicle weight, the road inclination and the like. By the above method, it is possible to increase the efficiency of the operation of a motor vehicle and its energy consumption, ie a fuel consumption in an internal combustion engine as a drive motor or a consumption of electrical energy in an electric motor as a drive motor whose consumption of urea (for the exhaust aftertreatment of diesel exhaust gases of a Diesel engine as a drive motor), the wear of an internal combustion engine as a drive motor, a noise of the drive motor and a pollutant emissions of an internal combustion engine as a drive motor to reduce. The energy saving is noticeable in particular in uneven driving distances in city traffic with frequent acceleration phases and with changing payload of the motor vehicle. The above method allows the To support driving style of the driver that this regardless of the total vehicle weight and regardless of the roadway inclination receives an unchanged operating feel for the motor vehicle.

Furthermore, it should be achieved with the above method that only the amount of energy that is necessary to move the vehicle with a propulsion that is desired by the driver or that leads to a predetermined acceptable acceleration is used.

It can be provided that the propulsion request is specified as a measure of an operation of a driving control device, wherein in particular the driving control device corresponds to an accelerator pedal and the propulsion request is specified as accelerator pedal position. The driver control device may also correspond to another device by which a propulsion request is specified, such. B. from an engine control unit or the like.

According to one embodiment, the determination of the adaptation variable can be carried out with the aid of a predefined characteristic field as a function of the total vehicle weight and / or of the roadway inclination, with interpolation in particular between reference points of the characteristic field. This map can be determined empirically, for example.

Furthermore, depending on the drive motor torque, one or more drive variables for the drive motor, in particular a fuel quantity for a diesel engine as a drive motor or a drive current or a duty cycle of a PWM drive in an electric motor as the drive motor, can be determined.

According to one embodiment, a nominal drive torque may be determined depending on the drive request and on a state of a drive motor, wherein the adjustment amount corresponds in particular to an adjustment factor with which the nominal drive torque is multiplied in order to obtain the drive motor torque.

It can be provided that the nominal drive torque is determined in particular as a function of a rotational speed of the drive motor by means of a drive torque characteristic field.

Furthermore, the drive motor torque can be set equal to the nominal drive torque when the predetermined propulsion request exceeds a predetermined threshold. In this way, for example, a kickdown of the accelerator pedal can be converted directly into a maximum propulsion request.

The determination of the total vehicle mass can be performed cyclically, leaving the total vehicle mass unchanged when a predetermined condition is met.

• – die Fahrzeuggeschwindigkeit ist geringer als eine vorgegebene Mindestgeschwindigkeit;
• – die Fahrzeuglängsbeschleunigung ist geringer als eine vorgegebene Mindestbeschleunigung;
• – die Bremse ist betätigt; und
• – die angeforderte Fahrzeugbeschleunigung ist größer als eine Fahrzeugbeschleunigungsschwellenwert,

wobei die vorgegebene Bedingung erfüllt ist, wenn die eine oder die mehreren Bedingungen der berücksichtigten Bedingungen gemeinsam erfüllt sind.In particular, the given condition may take into account one or more of the following conditions:

• The vehicle speed is less than a predetermined minimum speed;
• - The vehicle longitudinal acceleration is less than a predetermined minimum acceleration;
• - the brake is applied; and
• The requested vehicle acceleration is greater than a vehicle acceleration threshold,

wherein the predetermined condition is satisfied when the one or more conditions of the considered conditions are satisfied together.

• – ein von einem Fahrer vorgegebener Vortriebswunsch für das Kraftfahrzeug zu erfassen;
• – eine Anpassungsgröße abhängig von einem Fahrzeuggesamtgewicht und/oder einer Fahrbahnneigung zu bestimmen;
• – ein Antriebsmotormoment abhängig von der Anpassungsgröße und dem Vortriebswunsch zu ermitteln, und
• – einen Antriebsmotor des Kraftfahrzeugs abhängig von dem Antriebsmotormoment zu betreiben.

In another aspect, there is provided an apparatus for operating a motor vehicle, the apparatus being configured to:

• - To detect a predefined by a driver propulsion request for the motor vehicle;
• To determine an adaptation quantity depending on a gross vehicle weight and / or a road gradient;
• - To determine a drive motor torque depending on the adaptation size and the propulsion request, and
• - To operate a drive motor of the motor vehicle depending on the drive motor torque.

• – eine Fahrbedieneinrichtung zur Vorgabe eines Vortriebswunsches;
• – einen Verbrennungsmotor zum Antrieben des Kraftfahrzeugs;
• – die obige Vorrichtung.

According to a further aspect, a motor vehicle is provided, comprising:

• - A driver control device for specifying a propulsion request;
• - An internal combustion engine for driving the motor vehicle;
• - The above device.

Brief description of the drawings

Embodiments are explained below with reference to the accompanying drawings. Show it:

1 a schematic representation of a commercial vehicle; and

2 a functional diagram illustrating a method for determining a drive motor torque to provide the desired vehicle acceleration.

Description of embodiments

1 shows a schematic cross-sectional view through a commercial vehicle 1 (Motor vehicle) with an internal combustion engine 2 as a drive motor, via an engine control unit 3 is driven to provide a drive torque. The internal combustion engine 2 In commercial vehicles is usually designed as a diesel engine, but it can also be provided a different type of internal combustion engine. Alternatively, the drive motor may also be provided as an electric motor.

The engine control unit 3 stands with a driver control device 4 in connection, through which the driver can specify a propulsion request. In particular, in an accelerator pedal as a driving control device 4 assumed an accelerator pedal position as an indication of a propulsion request. The propulsion request indicates a desired vehicle movement, in particular a desired vehicle acceleration.

Furthermore, the engine control unit detects 3 further vehicle state variables and controls the internal combustion engine 2 in a corresponding manner depending on the driving desire of the driver and the vehicle state variables.

The engine control unit 3 can be an accelerometer 5 included or associated with such a slope of the carriageway on which the commercial vehicle 1 moves to detect. The acceleration sensor 5 can also be in another control unit in the motor vehicle 1 or as a separate sensor element. The signal of the acceleration sensor 5 can be used to determine the total vehicle mass and the road grade.

In 2 is a functional diagram shown, the determination of an adapted drive motor torque M as a default for a control of the internal combustion engine 2 represents. Based on an accelerator pedal position FP, which may for example be indicated in percent displacement of the accelerator pedal, and an engine speed n is determined by means of a suitable drive torque map 11 a nominal drive torque M _n provided. This nominal drive torque M _n corresponds to the drive torque, which in conventional engine systems as control for the internal combustion engine 2 is given. The drive motor torque M is for this purpose given a torque calculation path that corresponds to an algorithm implemented in the engine control unit. In the torque calculation path, the control variables for the internal combustion engine 2 generated. In particular, from the given drive motor torque in a diesel engine as an internal combustion engine 2 determines an amount of fuel to be injected, through which the desired by the accelerator pedal position drive motor torque M is provided.

The nominal drive torque M _n becomes a multiplier 12 to be multiplied there by an adjustment factor AF (corresponding to the adjustment amount) to obtain the drive torque M to be used for driving the internal combustion engine. The adaptation factor AF can correspond to a factor between 0 and 1 and serve that of the internal combustion engine 2 Required drive motor torque M compared to the nominal drive torque M _N to reduce if the predetermined by the accelerator pedal position FP propulsion request is too high due to an intuitively misjudged vehicle behavior due to a different total vehicle mass and a changed road inclination. Instead of the adaptation factor AF, it is also possible to use a different adaptation variable with which the nominal drive torque M _{n is} acted upon in a manner other than multiplicative, for example. B. additive or the like.

wobei m der Fahrzeuggesamtmasse, v der Fahrzeuggeschwindigkeit, M einem Motormoment, J_e einem Trägheitsmoment des Verbrennungsmotors, ω der Motorgeschwindigkeit und r_g dem Radradius geteilt durch das (insbesondere durch die Fahrstufenwahl) vorgegebene Übersetzungsverhältnis eines Schaltgetriebes entsprechen. Insbesondere gilt:

wobei r_w dem Radradius, g_d dem Übersetzungsverhältnis und g_f dem Antriebsverhältnis entsprechen. To determine the adaptation factor AF, a total vehicle mass m is determined. This can already be done in the engine control unit 3 be provided or appropriately calculated by a separate algorithm. The mass estimate can be a mass estimation block 13 be made as follows:

where m is the total vehicle mass, v is the vehicle speed, M is an engine torque, J _{e is} a moment of inertia of the internal combustion engine, ω is the engine speed and r _{g is} the wheel radius divided by the (in particular by the speed selector) predetermined transmission ratio of a gearbox. In particular:

where r _{w is} the wheel radius, g _{d is} the gear ratio, and g _{f is} the drive ratio.

F _fb corresponds to the friction braking force at the wheels, F _aero the aerodynamic braking force with F _aero = 1 / 2C _d ρAv C _d correspond to an air resistance coefficient, p the air density and A of the flow front surface of the vehicle.

F _grade corresponds to a road _grade force as follows: F _grade = mg (μcosβ + sinβ) where g is the gravitational constant, μ the rolling resistance of the road and β the road inclination.

The road gradient can be from the acceleration sensor 5 or derived from GPS data. The road grade is in the road grade block 14 determined and an adjustment factor map 15 provided. The adaptation factor AF from the adaptation factor map 15 becomes a selector 16 supplied by a comparator 17 is controlled. In the comparison element 17 the accelerator pedal position is compared with a threshold for an accelerator pedal position FP _s and a result of the comparison to the selector 16 provided. The accelerator pedal position threshold value is used to detect whether the driver wants to use the nominal drive motor torque as a propulsion request. This can be done, for example, by a considerable actuation of the accelerator pedal 4 , z. As in a kick-down, are recognized, and be recognized so that the driver desires a very high acceleration of the motor vehicle. In this case, the adaptation factor is the multiplier element 12 given a factor of 1, otherwise from the adaptation factor map 15 predetermined adjustment factor AF.

For example, the adaptation factor map 15 following map include: Total vehicle mass [kg] 3700 3300 3000 2600 2300 2000 Road inclination [%] 6 1 1 1 1 1 0.9 5 1 1 1 0.9 0.8 0.7 3 1 0.95 0.9 0.75 0.72 0.65 0 1 0.9 0.85 0.72 0.7 0.6 -3 1 0.85 0.8 0.7 0.68 0.58 -5 0.95 0.8 0.75 0.65 0.6 0.5 -6 0.95 0.8 0.7 0.6 0.55 0.45

It can be seen that with decreasing road inclination and with decreasing total vehicle mass the adaptation factor drops to values <1.

The map is determined empirically, and intermediate values can be determined by interpolation.

• – die Fahrzeuggeschwindigkeit ist geringer als eine vorgegebene Mindestgeschwindigkeit;
• – die Fahrzeuglängsbeschleunigung ist geringer als eine vorgegebene Mindestbeschleunigung;
• – die Bremse ist betätigt; und
• – die angeforderte Fahrzeugbeschleunigung ist größer als ein Fahrzeugbeschleunigungsschwellenwert.

The determination of the total vehicle weight m according to the above method can be performed permanently. Alternatively, the determination of the total vehicle weight can be stopped if a corresponding condition exists. The corresponding condition may be met when one or more of the following conditions or conditions are shared:

• The vehicle speed is less than a predetermined minimum speed;
• - The vehicle longitudinal acceleration is less than a predetermined minimum acceleration;
• - the brake is applied; and
• The requested vehicle acceleration is greater than a vehicle acceleration threshold.

If the determination of the total vehicle weight is not updated due to the presence of the corresponding condition, the last calculated value of the total vehicle weight is assumed or, in particular after a start of the motor vehicle, a predetermined total vehicle weight is assumed.

Claims (13)

Method for operating a motor vehicle ( 1 ), comprising the following steps: detecting a driving intention for the motor vehicle specified by a driver ( 1 ); Determining an adaptation variable (AF) as a function of a total vehicle weight (m) and / or a road gradient; Determining a drive motor torque (M) as a function of the adaptation variable (AF) and the propulsion request, operating a drive motor ( 2 ) of the motor vehicle ( 1 ) depending on the drive motor torque (M). The method of claim 1, wherein the propulsion request as a measure of an operation of a driving control device ( 4 ), in particular the driver control device ( 4 ) corresponds to an accelerator pedal and the propulsion request as the accelerator pedal position (FP) is specified. Method according to one of claims 1 to 2, wherein the determination of the adaptation variable (AF) depending on the total vehicle weight (m) and / or the road inclination is performed using a predetermined map, in particular interpolated between nodes of the map. Method according to one of claims 1 to 3, wherein depending on the drive motor torque (M) one or more drive variables for the drive motor ( 2 ), in particular a fuel quantity for a diesel engine as a drive motor ( 2 ) or a drive current or a duty cycle of a PWM control of an electric motor as a drive motor can be determined. Method according to one of claims 1 to 4, wherein a nominal drive torque (M _n ) depending on the propulsion request and depending on a state of a drive motor ( 2 ), wherein the adjustment amount (AF) corresponds in particular to an adjustment factor (AF) with which the nominal drive torque (M _n ) is multiplied in order to obtain the drive motor torque (M). Method according to Claim 5, wherein the nominal drive torque (M _n ) is determined by means of a drive torque characteristic field, in particular as a function of a rotational speed (n) of the drive motor ( 2 ) is determined. Method according to one of claims 5 to 6, wherein the drive motor torque is set equal to the nominal drive torque (M _n ) when the predetermined propulsion request exceeds a predetermined threshold value (FS _s ). Method according to one of claims 1 to 7, wherein the determination of the total vehicle mass is performed cyclically, wherein the determined total vehicle mass (m) is left unchanged when a predetermined condition is met. The method of claim 8, wherein the predetermined condition takes into account one or more of the following conditions: the vehicle speed is less than a predetermined minimum speed; - The vehicle longitudinal acceleration is less than a predetermined minimum acceleration; - the brake is applied; and the requested vehicle acceleration is greater than a vehicle acceleration threshold, wherein the predetermined condition is met when the one or more conditions of the considered conditions are satisfied together. Device for operating a motor vehicle ( 1 ), wherein the device is designed to: a propulsion request for the motor vehicle specified by a driver ( 1 ) capture; To determine an adaptation variable (AF) as a function of a total vehicle weight (m) and / or a road gradient; To determine a drive motor torque (M) as a function of the adaptation variable (AF) and the propulsion request, 2 ) of the motor vehicle ( 1 ) depending on the drive motor torque (M) to operate. Motor vehicle comprising: - a driving control device ( 4 ) for specifying a propulsion request; A drive motor ( 2 ) for driving the motor vehicle ( 1 ); - An apparatus according to claim 10. Computer program adapted to carry out all the steps of a method according to one of Claims 1 to 9. A machine-readable storage medium on which a computer program according to claim 12 is stored.

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