WO2014199042A1

WO2014199042A1 - Method of anti-overspeed control for a power train of a motor vehicle

Info

Publication number: WO2014199042A1
Application number: PCT/FR2014/051267
Authority: WO
Inventors: François Plante
Original assignee: Renault S.A.S
Priority date: 2013-06-11
Filing date: 2014-05-28
Publication date: 2014-12-18
Also published as: FR3006652B1; BR112015030224A2; RU2015155437A; FR3006652A1; CN105263778A; EP3007951A1

Abstract

The invention concerns a method for controlling a power train (2) of a motor vehicle (1), said power train comprising an engine (3) and a gearbox (5) connected together by a coupling device (4). The invention involves the following steps: a) acquiring control parameters of the motor vehicle, including an item of tilt data (α) relative to the slope on which the motor vehicle is located, and a speed (V) of the motor vehicle, b) checking, on the basis of the parameters acquired in step a), if the motor vehicle is in a configuration in which overspeed is likely, then, if the motor vehicle is in a configuration in which overspeed is likely, c) controlling a change in the gearbox ratio or informing the driver of the possibility of changing the gearbox ratio, from a first ratio for travel in one direction to a second ratio for travel in a second direction, and, d) when the second ratio is engaged, controlling the engine at a predefined speed setpoint.

Description

METHOD FOR CONTROLLING ANY PACKAGING OF A GROUP

MOTOR VEHICLE MOTORPROOF

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates generally to the automotive industry.

It relates more particularly to a driving method of a powertrain of a motor vehicle, the powertrain comprising a motor and an automatic gearbox connected together by a coupling device such as a double clutch, a hydraulic clutch or a converter hydraulic torque.

The invention finds a particularly advantageous application in the production of motor vehicles with automatic transmission called "off-road", including four-wheel drive vehicles (military vehicles, emergency vehicles, construction site vehicles or mining extraction, ...).

BACKGROUND

When a vehicle descends a slope (forward or reverse), the driver's control of the speed of the vehicle can be tricky, especially when the ground clearance is low (muddy or snow-covered terrain, ice, gravel, abundant vegetation, ...).

If the driver is not careful or only has a little experience, it can happen that the vehicle takes too much speed and becomes uncontrollable. Indeed, at high speed, the slightest action on the brakes of the vehicle results in a loss of grip and directivity. The motor vehicle is said to be racing.

To avoid any loss of control of the vehicle, it is known to equip the latter with a stability control system (commonly called "ESP system", the acronym for "Electronic Stability Program") which drives the wheels of the vehicle in such a way that independent, and thanks to which the driver can regain control of his vehicle as long as the speed reached is not too high. However, it is observed that in this configuration of precarious adhesion, these ESP systems are not always sufficiently effective. These ESP systems also have the disadvantage of strongly applying the brakes (at the expense of their longevity). These ESP systems are also very expensive, so they are not installed on all ranges of vehicles.

OBJECT OF THE INVENTION

The present invention then proposes another method to prevent runaway of the motor vehicle when it comes down a low grip terrain, which does not require an ESP system.

More particularly, it is proposed according to the invention a control method comprising steps:

a) acquisition of driving parameters of the motor vehicle, including inclination data relating to the slope on which the motor vehicle is located, and a speed of the motor vehicle,

b) verification, according to the parameters acquired in step a), if the motor vehicle is in a configuration likely to runaway, then, if the motor vehicle is in a runaway configuration,

c) control of a change gear ratio or information to the driver of the possibility of changing gear ratio, from a first gear in one direction to a second gear ratio in the opposite direction and,

d) when the second gear is engaged, controlling the engine according to a determined target speed of the vehicle.

It is therefore understood that the passage of the first gear (for example forward) to the second gear (reverse gear) will cause the application of a torque to the wheels of opposite sign to that of the driving torque of the vehicle related to the force of gravity applied to the vehicle, which will therefore generate a braking torque on the wheels of the motor vehicle.

The algebraic resultant of these two couples applied to the driving wheels will have the effect, according to their respective values, of braking or accelerating the vehicle. Since the driving torque linked to the force of gravity can not be controlled, the braking torque can then simply be adjusted by means of a conventional vehicle speed regulator, which will thus accurately and smoothly control the speed of the vehicle. automobile, which will prevent the motor vehicle from racing.

This solution smooths the braking torque, which suddenly avoids detrimental to the motor skills, directivity and braking efficiency of the vehicle.

This smoothing of the braking torque also ensures better comfort for the driver and the passengers.

Moreover, there are known powertrains equipped with a hydraulic coupling device called torque converters. Their design has the disadvantage that if the output shaft of this converter and the input shaft rotate in an opposite direction, it develops a reaction torque that is opposed to the rotation of the shaft in connection with the engine. Then, if the relative speed between the input shaft and the output shaft of the converter becomes high enough, the reaction torque can become greater than the torque that the engine is able to deliver, which eventually stall engine .

The device which is the subject of the invention then implicitly makes it possible to avoid any stalling of the motor.

This solution also makes it possible to limit the wear of the brake linings since the braking is here carried out using only the engine.

Finally, this solution is particularly inexpensive since it does not require any particular arrangement in the motor vehicle. It must only be located in one of the computers of the motor vehicle, preferably in the engine control computer or the automatic transmission. It may eventually bring amenities in the vehicle, but they remain limited, for example the addition of a light or an activation button and disabling the anti-runaway mode of the vehicle.

Other advantageous and non-limiting features of the control method according to the invention are the following: in step d), the engine is controlled by means of a cruise control function implemented in a computer fitted to the motor vehicle;

in step a), information is acquired for manually activating or deactivating an anti-runaway mode of the motor vehicle, and, in step b), it is checked whether the motor vehicle is in a configuration capable of also depending on said activation or deactivation information;

in step a), braking information relating to the position of the force exerted on a brake pedal fitted to the motor vehicle is acquired, and, in step b), it is checked whether the motor vehicle is in a configuration likely to runaway also according to said braking information;

in step a), acceleration information relative to the position of or the force exerted on an accelerator pedal equipping the motor vehicle is acquired, and, in step b), it is verified that if the motor vehicle is in a configuration likely to runaway also according to said acceleration information;

in step a), an acceleration of the motor vehicle is acquired, and, in step b), it is checked whether the motor vehicle is in a configuration capable of racing also according to said acceleration;

said inclination datum is calculated as a function of said braking information, said acceleration will information and said acceleration;

said tilt datum is measured by a gyroscope equipping the motor vehicle;

in step a), said inclination data is acquired by means of a GPS coupled to a three-dimensional cartography;

- In step a), one acquires a gear ratio information engaged and / or interconnection information relating to the two or four wheel drive mode in which the motor vehicle is located and / or a braking-parking information relating to the position of a handbrake equipping the motor vehicle, and, in step b), it is checked whether the motor vehicle is in configuration may runaway also according to said gear ratio information engaged and / or said interconnection information and / or said braking-parking information.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT

The following description with reference to the accompanying drawings, given as non-limiting examples, will make it clear what the invention consists of and how it can be achieved.

In the accompanying drawings:

- Figure 1 is a schematic view of a motor vehicle comprising a computer adapted to implement a control method according to the invention;

FIG. 2 is a logic diagram illustrating the algorithm for implementing the method according to a first embodiment of the invention; and

FIG. 3 is a logic diagram illustrating the algorithm for implementing the method according to a second embodiment of the invention.

In FIG. 1, there is shown a motor vehicle 1 which conventionally comprises two front wheels 7, two rear wheels 8, and a power unit 2.

This is a motor vehicle called "off-road", four-wheel drive. It could alternatively be a two-wheel drive motor vehicle.

The powertrain 2 comprises a motor 3 whose motor shaft is connected to the input shaft of an automatic gearbox 5 via a coupling device 4. It also comprises a jaw clutch device 6 which allows connect the output shaft of the gearbox 5 to either the front wheels 7 only (two-wheel drive mode) or to all four wheels 7, 8 (four-wheel drive mode).

The engine 3 will preferably be a spark ignition internal combustion engine (gasoline) or compression ignition (diesel). Alternatively, it may also be an electric motor. Alternatively also, it may also be a so-called hybrid powertrain, combining an electric motor and a gasoline engine or diesel type. The automatic gearbox 5 is preferably an epicyclic gearbox (it could also be of the continuously variable ratio type). Such a box is, in known manner, equipped with brakes or clutches which are adapted to release or block some of the elements of the planetary gear trains to select one or the other of different gear ratios.

The coupling device 4 is preferably a hydraulic torque converter. In known manner, such a hydraulic torque converter comprises three paddle wheels which are immersed in an oil bath. One of the paddle wheels, called impeller, is connected to the motor shaft. Another paddle wheel, called a turbine, is connected to the input shaft of the gearbox 5. The rotation of the impeller is then provided to put the oil in motion and thus gradually cause the turbine to rotate. . A last paddle wheel, called reactor, is provided to accelerate the rotational drive of the turbine by the impeller.

According to a first variant, it could be provided that the automatic gearbox is an epicyclic gearbox and that the coupling device is a hydraulic clutch (that is to say a hydraulic torque converter without a reactor).

According to a second variant, it could be provided that the automatic gearbox is a belt box and that the coupling device is a hydraulic clutch.

According to a third variant, it could be provided that the automatic gearbox is a belt box and that the coupling device is a hydraulic torque converter.

According to a fourth variant, it would be possible for the automatic gearbox to be a gearbox mounted on parallel shafts and for the coupling device to be a double-clutch.

In the preferred embodiment of the powertrain and in all the variants mentioned above, the automatic gearbox 5 comprises at least a forward speed ratio (D ratio), and a rear speed ratio (R ratio). In the following description, it will be considered that the powertrain 2 is made according to the preferred mode.

The motor vehicle 1 also comprises, as conventionally, a brake pedal 9, an accelerator pedal 10, a shift or shift lever 1 1, and a handbrake 12.

The shifting lever 1 1 makes it possible in particular to switch from the ratio D to the ratio R and vice versa.

In the first embodiment of the invention, this gearshift lever 1 1 electronically control this gearshift, via an electronic circuit ad hoc.

In the second embodiment of the invention, this shift lever 1 1 will mechanically control this gear shift, via a wire rope and a hydraulic valve actuated by this cable.

The motor vehicle 1 here also comprises, in a specific manner to the invention, a means for activating and deactivating an anti-packaging mode of the motor vehicle 1, and information means 13, 14 making it possible to provide the information about this anti-packaging mode.

This anti-runaway mode will be described in more detail later in this talk.

The means for activating and deactivating the anti-runaway mode is here in the form of a bistable button 15, allowing the driver to activate or deactivate the anti-runaway mode manually.

Alternatively, the activation and deactivation means could of course be in another form (tilting lever, touch button, lever position corridor, voice control ...).

Alternatively also, the activation and deactivation means could be obtained by an already existing means of choosing the configuration of the operation of the vehicle or its powertrain, or its driveline, as a means of activating or deactivating the vehicle. mechanical coupling between the front wheels and the rear wheels. The means of information are presented here in the form of a sound device 13 adapted to emit an audible sound by the driver (in practice, it may be the speakers fitted to the motor vehicle) and a witness light 14 located on the dashboard of the motor vehicle 1.

As a variant, the information means could of course be in another form (vibrations in the steering wheel or in the driver's seat, pilot light on the steering wheel, etc.).

To control the various components of the powertrain 2, in particular the engine 3 and the automatic gearbox 5 (in the first embodiment of the invention), the motor vehicle 1 comprises a computer 20 which comprises a processor (CPU), random access memory (RAM), read only memory (ROM), analog-to-digital converters (AD), and different input and output interfaces.

Thanks to its input interfaces, the computer 20 is adapted to receive different sensors of the driving parameters of the motor vehicle 1.

In its RAM, the computer 20 thus stores continuously:

the speed V of the motor vehicle 1, measured by means of a sensor placed on the shaft of one of the front wheels 7 of the motor vehicle 1,

a braking command If relative to the position of the brake pedal 9 or to the force exerted on the brake pedal 9 by the driver, measured with the aid of a pressure or position sensor, or a contactor testifying to an effective action of bearing on the brake pedal, placed under the brake pedal 9,

- a throttle l _has on the position of the accelerator pedal 10 or the force exerted on the accelerator pedal 10, measured using a pressure sensor or position under the accelerator pedal 10,

a piece of clutch information l _c relating to the two or four wheel drive mode in which the motor vehicle 1 is located, measured by means of a position sensor placed in the jaw clutch device 6, or alternatively, obtained by the computer in charge of controlling the interconnection device,

a braking-parking information l _fp relating to the position of the parking brake 12, measured using a contactor testifying to the actual state actuating the parking brake, or a position sensor placed in the parking brake 12, or obtained by the computer responsible for controlling the tightening / loosening of an automatic parking brake,

an engaged ratio information li relating to the position of the shift lever 1 1, measured with the aid of a position sensor placed in the shift lever 1 1, and

- Activation or deactivation information l _a / d anti-packaging mode, measured using a status sensor placed in the bistable button 15.

Thanks to a predetermined mapping on test bench and to software stored in its read-only memory, the computer 20 is adapted to determine other driving parameters of the vehicle.

The computer 20 is thus particularly suitable for determining:

the acceleration A _cc of the motor vehicle 1 as a function of the measured speeds V, and

the inclination α of the slope on which the motor vehicle 1 is located, as a function of the acceleration A _cc , the speed V, the braking command I _f and the acceleration command l _a .

Of course, alternatively, these values of acceleration and inclination could be obtained otherwise. They could thus be measured using an accelerometer or a gyroscope.

Alternatively, the inclination could also be acquired using a GPS chip associated with mapping software, which would then indicate the inclination of the slope according to the position and the direction of advancement of the vehicle automobile.

In any event, thanks to the maps and software stored in its read-only memory, the computer 20 is also adapted to generate output signals, as a function of the set of acquired control parameters (measured and determined).

Finally, thanks to its output interfaces, the computer 20 is adapted to transmit the output signals to the various components of the engine. It is thus particularly adapted to transmit: a speed setpoint ω ₀ to the motor 3,

an ignition or extinction command C ₂ at the light indicator 14,

a set point for delivering a message Ci to the speakers 13, and

in the first embodiment of the invention, a control set point C3 to the automatic gearbox 5.

According to a particularly advantageous characteristic of the invention, the computer 20 is adapted to implement a control method comprising steps:

a) acquisition of driving parameters of the motor vehicle, at least the inclination of which has slope and the speed V of the motor vehicle 1,

b) verification, according to the parameters acquired in step a), if the motor vehicle 1 is in a configuration likely to runaway, then, if that is the case,

c) controlling an automatic gearbox shift (first embodiment of the invention) or informing the driver of the possibility of changing the gearbox ratio (second embodiment of the invention); invention), from a first gear ratio in one direction to a second reverse gear ratio, and,

d) when the second gear is engaged, controlling the motor 3 to a speed setpoint ω ₀ determined.

The present invention is particularly useful when a vehicle descends a slope (forward or reverse), since the control of the speed of the vehicle by the driver can be difficult, especially when the ground adhesion is low (muddy or covered with snow, ice, gravel, abundant vegetation, ...).

It is said that the motor vehicle is in a configuration likely to runaway. This configuration is detected by the computer using the parameters acquired in step a).

Thanks to the invention, after detecting this configuration, the computer 20 can either automatically place the powertrain in anti-packaging mode (in the first embodiment, by controlling the automatic gearbox on the reverse ratio and then driving the engine accordingly) , either ask the driver to switch the reverse gear (in the second embodiment) to then drive the engine in anti-runaway mode.

In the remainder of the description, it will be considered that the vehicle descends in advance of a slope, but the invention will apply in the same way if the vehicle descends in a reverse slope.

FIG. 2 shows the various steps of the method according to the invention, when the automatic gearbox 5 is driven electronically (first embodiment of the invention).

In step a), the computer 20 measures and stores:

the speed V of the motor vehicle 1,

the brake control If,

- the acceleration control l _has ,

- the interconnection information l _c ,

- the braking-parking information l _fp ,

the committed report information li, and

- the activation or deactivation information l _{a / d} of the anti-packaging mode.

The calculator 20 also determines and stores:

the acceleration A _cc of the motor vehicle 1, and

- slope inclination of the slope.

In step b), the computer 20 checks whether the motor vehicle 1 is in a runaway configuration.

The computer 20 considers that the motor vehicle 1 is in a runaway configuration if all the following conditions are met:

- committed reporting information indicating that report D is engaged,

- V speed positive and greater than a first threshold (for example 5 km / h),

- the throttle _is less than a second threshold (for example corresponding to one fifth of the stroke of the accelerator pedal 10),

- acceleration A _cc positive and greater than a third threshold (for example greater than 1 m.s s ^"2 ), - If null brake command for a predetermined duration (for example 1 second),

- Linking information l _c indicating that the motor vehicle 1 is in four-wheel drive mode,

activation or deactivation information the _d indicating that the anti-runaway mode has been engaged by the driver,

- parking braking information l _fp indicating that the parking brake 12 is released,

inclination has greater than a fourth threshold (for example 20% slope).

If at least one of these conditions is not met, the computer 20 resets the process, returning to step a).

Otherwise, the computer 20 implements step c).

During this step c), the computer 20 transmits to the automatic transmission 5 a control set C3, so that it automatically engages the R ratio of reverse (while the motor vehicle continues to advance).

It is understood that this change of ratio will cause a braking torque on the four wheels 7, 8 of the motor vehicle 1. This braking torque will be all the more important as the motor shaft will turn quickly.

In step d), the computer 20 then drives the engine 3 according to a speed setpoint ω ₀ determined, so as to adjust at best and at each instant this braking torque.

This speed set point will be predetermined here and chosen sufficiently low to avoid any risk of loss of control of the vehicle (for example 3 to 4 km / h).

As a variant, this speed reference could be determined according to the parameters acquired in step a). It can thus be chosen even greater than the inclination a will be weak,

Preferably, the control of the motor 3 according to this speed setpoint ω ₀ is achieved by means of a "speed regulator" function which is well known and which is implanted natively in the computer 20 to enable the driver to release the accelerator pedal on the highway. It will not be necessary to develop an algorithm dedicated to this piloting.

Finally, advantageously, it can be provided that when the power unit 2 is in anti-runaway mode, the computer 20 controls the lighting of the indicator light 14.

It can also be provided that the computer 20 controls the diffusion by the speakers 13 of a message when the motor vehicle 1 out of this anti-runaway mode.

The output of this anti-runaway mode is automatically performed when at least one of the following conditions is met:

- the throttle _is greater than a fifth threshold (for example corresponding to one third of the stroke of the accelerator pedal 10),

non-zero braking command for a predetermined duration (for example 2 seconds),

- Linking information l _c indicating that the motor vehicle 1 is in two-wheel drive mode,

activation or deactivation information the _d indicating that the anti-runaway mode has been deactivated by the driver,

parking braking information l _fp indicating that the parking brake 12 has been tightened,

- oil temperature in the hydraulic torque converter that exceeds a seventh threshold value.

The hydraulic torque converter 4 is indeed highly stressed, which causes a significant heating of the oil it contains. This exit of the anti-runaway mode can thus avoid a too great rise in temperature of the oil. It will also be possible to prevent excessive heating of the oil by means of a process such as that described in documents FR2981 140 & WO2013050681.

FIG. 3 shows the various steps of the method according to the invention, when the automatic gearbox 5 is driven mechanically (second embodiment of the invention). In this second mode, steps a) and b) are performed in the same manner as in the first mode described with reference to FIG.

On the other hand, steps c) and d) are implemented differently.

In step c), the computer 20 is programmed to inform the driver that the motor vehicle 1 is in a runaway configuration.

For this, it is expected that it transmits to one or other of the information means 13, 14 a corresponding instruction.

It will thus be possible for it to transmit an ignition setpoint C ₂ to the indicator light 14 and / or a setpoint for delivering a message Ci to the speakers 13.

Thus, the driver is prompted to change the gearbox ratio, passing the reverse gear.

If it does not do this for a predetermined time TEMPO (for example 5 seconds), the computer 20 resets the process, returning to step a).

On the other hand, if it passes reverse gear, the computer controls, in step d), the engine 3 according to a determined speed setpoint ω ₀ , by means of the "cruise control" function.

As a variant of this second embodiment, provision may be made for the motor vehicle to be devoid of means for activating and deactivating the anti-runaway mode (that is to say here bistable button 15). In practice, the absence of this means will not be detrimental to the driver to the extent that it remains free to go or not reverse and then engage the anti-runaway mode.

According to a variant of this second embodiment, provision may be made to replace the indicator light 14 with a screen for displaying a message. Then, the driver will be prompted to change the gearbox ratio when this screen displays a corresponding message (for example a flashing letter R).

The present invention is not limited to the embodiments described and shown, but the skilled person will be able to make any other variant within his mind.

In a variant of the first embodiment, it can be provided that the motor vehicle is devoid of means for activating and deactivating the anti-runaway mode and means of information, in which case the computer will control the activation of the anti-runaway mode automatically, without activation on the part of the driver and without informing the driver.

In the variant where the inclination of the slope is acquired using a GPS chip associated with mapping software, it will also be possible to predict in advance the inclination of the slope, so as to engage the mode anti-packing even before the slope tilts.

Claims

1. Method for controlling a power unit (2) of a motor vehicle (1), said power unit (2) comprising a motor (3) and an automatic gearbox (5) connected together by a coupling device (4) characterized in that it comprises steps:

a) acquisition of driving parameters of the motor vehicle (1), including a tilt data (a) relating to the slope on which the motor vehicle (1) is located, and a speed (V) of the motor vehicle ( 1),

b) verification, according to the parameters acquired in step a), if the motor vehicle (1) is in a configuration likely to runaway, then, if the motor vehicle (1) is in a runaway configuration,

c) controlling a gearbox shift (5) or informing the driver of the possibility of changing the gear ratio (5) from a first gear ratio (D) in one direction towards a second ratio (R) of walking in the opposite direction, and,

d) when the second gear (R) is engaged, controlling the motor (3) according to a speed setpoint (ω ₀ ) determined.

2. Control method according to the preceding claim, wherein, in step d), the engine is controlled by means of a cruise control function located in a computer (20) equipping the motor vehicle (1).

3. Driving method according to one of the preceding claims, wherein, in step a), one acquires manual activation or deactivation (la / d) information of an anti-runaway mode of the motor vehicle ( 1), and in step b), it is checked whether the motor vehicle (1) is in a runaway configuration also based on said activation or deactivation information (d).

4. Control method according to one of the preceding claims, wherein, in step a), braking information (If) is acquired relative to the position of or to the force exerted on a brake pedal (9). ) equipping the motor vehicle (1), and in step b), it is checked whether the motor vehicle (1) is in configuration may runaway also according to said braking information (I _f ).

5. Driving method according to one of the preceding claims, wherein, in step a), one acquires acceleration information (l _a ) relative to the position of or the force exerted on a pedal of accelerator (10) equipping the motor vehicle (1), and in step b), it is checked whether the motor vehicle (1) is in a configuration that may runaway also according to said acceleration information (l _a ) .

6. Driving method according to one of the preceding claims, wherein, in step a), one acquires an acceleration (A _cc ) of the motor vehicle (1), and, in step b), one checks whether the motor vehicle (1) is in a runaway configuration also according to said acceleration (A _cc ).

7. A control method according to claims 4 to 6, wherein, in step a), said inclination data (a) is calculated according to said braking information (I _f ), said information of will d acceleration (l _a ) and said acceleration (A _cc ).

8. Driving method according to one of claims 1 to 6, wherein in step a), said inclination data is measured by a gyroscope equipping the motor vehicle.

9. Driving method according to one of claims 1 to 6, wherein in step a), said inclination data is acquired by means of a GPS coupled to a multidimensional map.

10. Driving method according to one of the preceding claims, wherein:

- In step a), acquires a gear ratio information engaged (li) and / or information interconnection (l _c ) relating to the two or four wheel drive mode in which the motor vehicle (1) and / or a braking-parking information (l _fp ) relating to the position of a parking brake fitted to the motor vehicle (1), and

in step b), it is checked whether the motor vehicle (1) is in a runaway configuration also according to said report information gear engaged (li) and / or said interconnection information (l _c ) and / or said braking-parking information (l _fp ).