DE102016221109A1 - Method and control system for operating a motor vehicle - Google Patents

Abstract

Proposed is a method for operating a motor vehicle with a Antriebsaggerat (1), with a between the Antriebsaggerat (1) and an output (2) of the motor vehicle connected transmission (3), and with one on the output (2) depending on a driver side Operation of a brake pedal (6) acting service brake (7), which is automatically executed depending on defined operating conditions of the motor vehicle when the brake pedal (6) in the transmission (3) a push-down. In this case, it is provided that an inertia torque available as a result of the embodiment of the push-down circuit is determined, and that a braking torque applied to the output (2) of the motor vehicle via the service brake (7) depends on the moment of inertia available as a result of executing the push-down shift is reduced.

Description

The invention relates to a method and a control system for operating a motor vehicle.

Motor vehicles with automatic transmissions are well known in practice. Thus, in a motor vehicle with an automatic transmission, the transmission is connected between a drive unit and an output. The transmission converts speeds and torques and thus provides the tractive power of the drive unit at the output.

From practice, it is also known that the operation of an automatic transmission is controlled and / or regulated by a transmission control unit. In this case, the transmission control unit controls the transmission depending on operating conditions of the motor vehicle such that circuits are automatically executed in the transmission. These may be upshifts or downshifts. The circuits can be executed in overrun mode or train operation of the drive unit. A downshift performed in overrun is referred to as a push downshift.

Then, when in a transmission of a motor vehicle, a push downshift is performed, an increase in rotational speed at the transmission input shaft. As a result, an engagement of the drive unit is usually caused in the sense of providing a positive drive unit torque. If necessary, this requires that the drive unit leaves a fuel cutoff of the same. This increases fuel consumption. Overall, this is disadvantageous.

On this basis, the invention is based on the object to provide a novel method and control system for operating a motor vehicle.

This object is achieved by a method according to claim 1.

According to a method for operating a motor vehicle with a Antriebsaggerat, with an arranged in the power flow between the Antriebsaggerat and an output of the motor vehicle automatic transmission, as well as with acting on the output of the motor vehicle depending on a driver side actuation of a brake pedal service brake of the motor vehicle, wherein depending on defined operating conditions of the motor vehicle when the brake pedal is actuated in the transmission automatically a push downshift is performed.

According to the invention, a moment of inertia available as a result of the embodiment of the push-down circuit is determined, and the braking torque applied via the service brake of the motor vehicle to the output of the motor vehicle is reduced as a function of the moment of inertia available as a result of executing the push-down shift.

With the present invention, it is proposed for the first time to automatically reduce the applied over the service brake of the motor vehicle at the output of the motor vehicle braking torque when executing a push-down of the automatic transmission with the brake pedal, depending on the available due to the execution of the push-down inertia. In this way, a positive engine intervention of the drive unit can be reduced or completely avoided. This can ultimately be saved fuel.

The term "positive engine engagement of the drive unit" is understood to mean a function by means of which the drive power of this drive unit is temporarily increased, ie as long as the positive engine intervention is effective.

Preferably, the moment of inertia available as a result of the execution of the push downshift is determined from a circuit-specific speed increase without intervention by the Antriebsaggerat. This determination of the moment of inertia available when the push downshift is executed is particularly simple and reliable.

According to an advantageous development of the invention, the brake torque applied at the output of the motor vehicle via the service brake is reduced in such a way that the moment of inertia available as a result of the embodiment of the push downshift is such that a cumulative wheel torque acting on the output is constant. Hereby, the motor vehicle can be operated particularly energy efficient and comfortable.

In a motor vehicle with hybrid drive, in which both an internal combustion engine and an electric machine is provided for driving, it can be provided that the brake torque applied via the service brake at the output of the motor vehicle depends on the moment of inertia available as a result of the execution of the push downshift is reduced, that a Rekuperationsmoment the electric machine is kept constant, and preferably a positive torque engagement of the electric machine and / or the internal combustion engine and optionally leaving a fuel cut of the Internal combustion engine is avoided or become. This makes it possible to operate the motor vehicle in a particularly energy-efficient manner.

In a motor vehicle whose drive unit is designed as an internal combustion engine and in which a torque converter is arranged as a starting element in the power flow between the internal combustion engine and the automatic transmission, it can be provided that the applied via the service brake at the output of the motor vehicle braking torque depends on the in sequence the embodiment of the thrust reversing available moment of inertia is reduced such that a positive torque engagement of the internal combustion engine and possibly an exit from a fuel cut of the internal combustion engine is or will be avoided. This makes a particularly efficient operation of the motor vehicle possible.

Even in a motor vehicle whose drive unit is designed as an internal combustion engine and whose automatic transmission is a double-clutch transmission, it can be provided that the applied via the service brake at the output of the motor vehicle braking torque is reduced depending on the available as a result of the execution of the push-down inertia in that a positive torque intervention of the internal combustion engine and possibly an exit from a fuel cut of the internal combustion engine is or are avoided. This makes a particularly efficient operation of the motor vehicle possible. Although the dual clutch is arranged as a starting element of the dual clutch transmission in the power flow between the engine and the fuselage gear and usually spatially seen before the hull gearbox, the dual clutch is to be understood as two switching elements of the transmission, which can perform during reverse gear push-downs, in the context of the inventive method to be viewed as.

The control system for operating a motor vehicle is defined in claim 9.

• 1 ein Blockschaltbild eines ersten Kraftfahrzeugs;
• 3 ein Blockschaltbild eines zweiten Kraftfahrzeugs; und
• 2 ein Zeitdiagramm zur weiteren Verdeutlichung der Erfindung.

Preferred developments emerge from the subclaims and the following description. Embodiments of the invention will be described, without being limited thereto, with reference to the drawings. Showing:

• 1 a block diagram of a first motor vehicle;
• 3 a block diagram of a second motor vehicle; and
• 2 a timing diagram for further clarification of the invention.

The invention relates to a method for operating a motor vehicle and to a control system for carrying out the method.

1 shows a highly schematic block diagram of an exemplary motor vehicle with hybrid drive. The motor vehicle of 1 includes a drive unit 1 which is an internal combustion engine 4 and an electric machine 5 includes. Between the drive unit 1 and a downforce 2 is an automatic transmission 3 connected. Further shows 1 a service brake 7 of the motor vehicle, the output 2 of the motor vehicle can provide a braking torque. That of the service brake 7 at the output 2 provided braking torque is dependent on whether and how a driver of the motor vehicle, the brake pedal 6 actuated.

The operation of the internal combustion engine 4 is from an engine control unit 8th controlled and / or regulated. The operation of the gearbox 3 is powered by a transmission control unit 9 controlled and / or regulated. In the embodiment of 1 takes over the gearbox control unit 9 also the control and / or regulation of the operation of the electric machine 5 and may therefore be referred to as a hybrid controller; Alternatively, for controlling or regulating the electric machine 5 but also be provided a separate control device. A brake control unit 10 takes over the control and / or regulation of the operation of the service brake 7 , The dashed arrows of the 1 illustrate a data exchange between the individual modules of the motor vehicle and the individual control units. This is how the engine control unit exchanges 8th with the internal combustion engine 4 and the transmission control unit 9 Data from. The transmission control unit 9 also exchanges with the electric machine 5 , the transmission 3 and the brake controller 10 Data from. The brake control unit 10 also exchanges with the service brake 7 and the brake pedal 6 Data from.

In the transmission 3 are automatically executed depending on defined operating conditions of the motor vehicle circuits. In particular, it is possible that, depending on a driver-side operation of the brake pedal 6 the transmission control unit 9 The gear 3 for the automatic execution of a push downshift controls. Then, if at the driver's side actuated brake pedal 6 in the transmission 3 automatically a push downshift is performed, a standing as a result of the execution of the push downshift moment of inertia is determined. This moment of inertia is preferably from the transmission control unit 9 calculated, depending on a speed increase, which is without intervention by the drive unit 1 formed.

Depending on the available as a result of the execution of the push downshift Moment of inertia is the over the service brake 7 at the output 2 reduced braking torque reduced. In the powertrain of 1 , So in a hybrid vehicle, the reduction of the service brake takes place 7 at the output 2 applied braking torque depending on the moment of inertia available as a result of the execution of the push-down, preferably such that a recuperation of the electric machine 5 is kept constant.

Preferably, a positive engine engagement of the electric machine continues 5 and the internal combustion engine 4 avoided, which is to be understood by the term "positive engine intervention" a temporary increase in the drive torque, which was not triggered by the driver via the accelerator pedal, but situational from the control unit of the respective drive unit. Preferably, it is also avoided that the internal combustion engine 4 an overrun fuel cut, which may be active, leaves.

The invention is not limited to the application in a motor vehicle with hybrid drive. Rather, the invention can also be used in the motor vehicle with purely internal combustion engine drive.

Also, the invention is not limited to application to a particular type of automatic transmission. Thus, for example, the invention in the motor vehicle of 2 be used, in which between the drive unit 1 which is in 2 exclusively an internal combustion engine 4 includes, and the gearbox 3 a converter 11 is switched. In the powertrain of 2 is that from the service brake 7 of the motor vehicle at the output 2 of the motor vehicle provided braking torque depending on the result of the execution of the transmission 3 reduced inertia torque available so reduced that a positive engine intervention of the internal combustion engine 4 reduced, preferably completely avoided, and optionally a fuel cut, in which the internal combustion engine 4 if necessary, must not be abandoned.

The invention can also be used, for example, in the motor vehicle, in which the automatic transmission is designed as a double-clutch transmission. Here too, the braking torque provided by the service brake of the motor vehicle at the output of the motor vehicle can be reduced in such a way that a positive engine intervention of the internal combustion engine is reduced, preferably completely avoided, and optionally an overrun fuel cutoff, depending on the moment of inertia available as a result of a push downshift provided in the dual clutch transmission. in which is operated if necessary, must not be abandoned. The thrust reverse, which are considered within the scope of the invention are due to the transmission concept gear change circuits of the dual clutch, ie circuits in which substantially simultaneously closed in the output gear clutch of the dual clutch and opened in the output gear clutch of the dual clutch is closed.

Further details of the invention will become apparent 3 , where in 3 over the time t several temporal curves 12 . 13 . 14 and 15 are shown. This visualizes a curve 15 the course of the speed at the transmission input shaft of the transmission 3 , The curve 14 visualizes a torque at the transmission output and in particular an inertia, which occurs when performing a push-down in the transmission 3 is available. The curve 13 visualizes one of the service brake 7 at the output 2 provided braking torque. The curve 12 visualizes a sum wheel torque at the output 2 , which is the sum of the curves 13 and 14 equivalent.

The curve 15 , which is the transmission input speed of the transmission 3 visualized, corresponds to the curve when performing a push downshift. As a result of the push downshift and the resulting increase in speed without positive engine intervention stands in 3 Moment of inertia at the gearbox output marked by the range I is available. As stated, this moment of inertia is preferably achieved by the transmission control unit 9 calculated on the control side. The transmission control device 9 provides this available moment of inertia to the brake control unit 10 to disposal.

The brake control unit 10 can according to the curve 13 that from the service brake 7 at the output 2 Adjust provided braking torque, namely, reduce, by the amount of the momentum available at the transmission output I. Since it is the braking torque 13 is a negative moment visualizes the increase of the curve 13 according to area II of the 3 a reduction of the negative braking torque. The summation wheel torque 12 stay constant.

It is therefore within the meaning of the present invention, in a push-down in the automatic transmission 3 , the driver-side operation of the brake pedal 6 and thus providing a braking torque via the service brake 7 at the output 2 is carried out, the part of the service brake 7 at the output 2 To reduce the braking torque provided, namely by an amount corresponding to the moment of inertia, which is available as a result of the execution of the thrust reverser on the transmission output, namely as a result of the circuit-specific speed increase of the corresponding thrust reversing without positive torque intervention on the drive unit 1 , This moment of inertia, the result of the execution of the thrust reverser on the transmission output of the transmission 3 and therefore available on the output side, is used for vehicle deceleration. In the hybrid vehicle of the 1 This can in particular the recuperation of the electric machine 5 kept constant. When the motor vehicle 1 or 2 A positive engine intervention can be reduced and possibly avoided, that of the internal combustion engine 4 a fuel cut ends or leaves.

LIST OF REFERENCE NUMBERS

1

power unit

2

output

3

transmission

4

internal combustion engine

5

electric machine

6

brake pedal

7

service brake

8th

Engine control unit

9

Transmission Control Module

10

Brake control unit

11

torque converter

12

curve

13

curve

14

curve

15

curve

Claims (10)

Method for operating a motor vehicle with a Antriebsaggerat (1), arranged in the power flow between the Antriebsaggerat (1) and an output (2) of the motor vehicle automatic transmission (3), and with one on the output (2) depending on a driver side Operation of a brake pedal (6) acting service brake (7) of the motor vehicle, depending on defined operating conditions of the motor vehicle when the brake pedal (6) in the transmission (3) is automatically carried out a push-down, characterized in that as a result of the execution of the push-down to Available inertia is determined, and that on the service brake (7) on the output (2) of the motor vehicle applied braking torque is reduced depending on the available as a result of the execution of the push-down inertia. Method according to Claim 1 , characterized in that the braking torque applied via the service brake (7) to the output (2) is reduced in such a way that a moment of inertia acting on the output (2) is constant as a function of the moment of inertia available as a result of the embodiment of the push-down system. Method according to Claim 1 or 2 , characterized in that the inertia moment available as a result of the execution of the push-down circuit is determined from a circuit-specific speed increase without intervention by the Antriebsaggerat (1). Method according to one of Claims 1 to 3 , characterized in that in a motor vehicle whose drive unit (1) has an internal combustion engine (4) and an electric machine (5), the brake torque applied via the service brake (7) to the output (2) of the motor vehicle depends on the result Execution of the inertia torque available in the transmission (3) is reduced such that a recuperation of the electric machine (5) is kept constant. Method according to Claim 4 , characterized in that the brake torque applied via the service brake (7) to the output (2) is reduced in such a way that a positive engine engagement of the electric machine (5) and / or the engine is provided as a function of the inertia torque available as a result of the embodiment of the push downshift Internal combustion engine (4) is avoided. Method according to one of Claims 1 to 3 , characterized in that in a motor vehicle, the drive unit (1) is designed as an internal combustion engine (4) and in which in the power flow between the internal combustion engine (4) and transmission (3) a torque converter (11) is arranged, the brake torque applied via the service brake (5) to the output (2) of the motor vehicle is reduced in such a way that a positive engine intervention of the internal combustion engine (4) is avoided, depending on the moment of inertia available as a result of the execution of the thrust reversing performed in the transmission (3) , Method according to one of Claims 1 to 3 , characterized in that in a motor vehicle, the drive unit (1) is designed as an internal combustion engine (4) and the transmission (3) is designed as a double clutch transmission, via the service brake (5) on the output (2) of the motor vehicle applied braking torque depending on the inertia torque available as a result of the execution of the push downshift in the transmission (3) is reduced in such a way that a positive engine intervention of the internal combustion engine (4) is avoided. Method according to one of Claims 4 to 7 , characterized in that the braking torque is reduced in dependence on the moment of inertia available as a result of the execution of the push-down circuit such that a departure from a fuel cut of the internal combustion engine (4) is avoided. Control system for operating a motor vehicle, comprising an engine control unit (8) for controlling and / or regulating the operation of at least a part of a drive unit (1), with a transmission control unit (9) for controlling and / or regulating at least the operation of a power flow between the drive gear (1) and an output (2) of the motor vehicle switched automatic transmission (3), as well as with a brake control unit (10) for controlling and / or regulating the operation of a on the output (2) of the motor vehicle depending on a driver-side operation of a brake pedal ( 6) acting on the service brake (7), wherein the transmission control unit (9) depending on defined operating conditions of the motor vehicle with actuated brake pedal (6) controls the transmission (3) for the automatic execution of a push-down, characterized in that the transmission control unit (9) in a row he moment of inertia available to the execution of the push downshift means, and that the brake control unit (10) reduces a brake torque applied to the output (2) via the service brake (7) as a function of the moment of inertia available as a result of the execution of the push-down shift. Control system after Claim 9 , characterized in that the same the method according to one of Claims 1 to 8th performs.

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