EP1276629A1

EP1276629A1 - Method and device for adjusting a gearbox step-up ratio in a motor vehicle comprising adaptive cruise control and/or a vehicle-speed controller

Info

Publication number: EP1276629A1
Application number: EP01929266A
Authority: EP
Inventors: Manfred Hellmann; Hermann Winner; Albrecht Irion
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2000-04-17
Filing date: 2001-03-27
Publication date: 2003-01-22
Also published as: JP2002029291A; WO2001079016A1; US6662098B2; DE10115052A1; US20020069009A1

Abstract

The invention relates to a method and a device for adjusting the gearbox step-up ratio of a gearbox fitted into the drive train of a motor vehicle, during the activation of an adaptive cruise control (ACC) system and/or a vehicle-speed controller. During said activation, a desired variable is predetermined. At least the drive motor of the vehicle is controlled depending on said desired variable. The invention is characterized in that if a first operating condition exists, said desired variable or a value that is derived from said desired variable is limited. The adjustment of the gearbox step-up ratio then takes place based on the limited variable or on the limited value. If a second operating condition exists, the adjustment of the gearbox step-up ratio takes place based on the desired variable or on the value. This prevents unnecessary and inconvenient shifting-down procedures during the ACC operation, without having to dispense with any rapid acceleration that may be necessary.

Description

Method and device for setting a gear ratio in a motor vehicle with a distance and / or vehicle speed controller

State of the art

The invention relates to a method and a device for setting a gear ratio in a motor vehicle with a distance and / or driving speed setting with the features of the independent claims.

Distance and / or vehicle speed controllers are also referred to, for example, as an adaptive cruise control system (ACC system).

From SAE paper 961010 (SAE Technical Paper Series 961010, International Congress & Exposition, Detroit, February 26-29, 1996, "Adaptive Cruise Control System - Aspects an Development Trends", inner, Witte, Uhler, Lichtenberg, Robert Bosch GmbH ) A radar-based ACC system is known, in which the multi-target radar sensor is attached to the front of a motor vehicle in order to determine distances and relative speeds from vehicles in front fed to a control unit via a bus system. This control unit uses the transmitted radar data and the driver's request to determine a corresponding acceleration request, which in turn is transmitted to a longitudinal control unit. The longitudinal control unit controls actuators in accordance with the acceleration requirement of the control unit. These actuators can be the motor of the motor vehicle, the clutch or the brakes of the motor vehicle. Due to the corresponding activation of the actuators, a certain behavior of the motor vehicle will result, which in turn is fed back to the control unit and thus forms a control loop. Depending on the corresponding acceleration request, either the drive train or the brakes are activated. With this selection, an estimated slope of the route is taken into account. In addition, the limits or the physical limitations of the drive train and the braking system must be known or must be calculated accordingly.

When combining an ACC system with an automatic transmission, care must be taken to avoid unnecessary downshifts of the transmission that reduce driving comfort during ACC regular operation.

Advantages of the invention

The invention relates to a method and a device for setting a gear ratio of a transmission installed in the drive train of a motor vehicle during the activation of a distance and / or driving speed setting system (ACC system). During the activation of the distance and / or vehicle speed setting system, a target size is specified, depending on gig of which at least the drive motor of the vehicle is controlled.

The essence of the invention is that when a first operating state (ACC normal operation) is present, this target variable or a value derived from this target variable is limited. The gear ratio setting is then made depending on the restricted size or depending on the restricted value. If there is a second operating state, the gear ratio is set depending on the desired size or depending on the value.

In relation to the background of the invention:

In a conventional motor vehicle with a gasoline engine, the driver of the vehicle generally actuates the engine's throttle valve directly. This results in a non-linear accelerator pedal engine torque characteristic to which the driver is usually accustomed. In newer vehicles, the driver no longer directly specifies the throttle valve position or the engine load by means of the accelerator pedal, but only his request for propulsion or the engine output torque or the engine output power. For this purpose, different engine output torques or the engine output powers are assigned to the accelerator pedal positions by means of a map. The selection of the transmission ratio for automatic transmissions is generally made essentially depending on the engine load (throttle valve position) and the driving speed.

To maintain the nonlinear accelerator pedal engine torque characteristic mentioned, a combination of an engine control system in which the throttle valve position is no longer specified directly by the accelerator pedal, with conventional transmission controls, the transmission shifting is carried out on the basis of a so-called "virtual" accelerator pedal value, instead of using the driver's torque or power request. The "virtual" accelerator pedal value corresponds to the real accelerator pedal value at which the would set required vehicle jacking. As a result, a problem arises when the target variable specified by the ACC system, for example a target torque, is close to the maximum torque of the engine. In this area, even a small change in the target torque leads to a large jump in the virtual accelerator pedal value, whereupon the transmission control switches spontaneously. If, in particular, there is only a small torque difference between the target torque and the maximum engine torque, this circuit is disruptive and uncomfortable. This phenomenon can be combated by limiting the inverse accelerator pedal value, for example to 80%. Such a limitation can also help in the ACC case, but prevents rapid downshifting when it is really needed.

The restriction according to the invention avoids uncomfortable gearshift operations of the transmission during ACC operation, without, however, preventing or delaying downshifting operations when stronger acceleration is really needed.

As mentioned in detail, it can be provided that the target variable represents a target value for the output torque or the output power of the vehicle engine. An actual variable representing the instantaneous output torque or the instantaneous output power of the vehicle engine is then determined. The second operating state according to the invention exists when the actual size differs from the target size in specifiable way deviates. In particular, it is provided that the second operating state is present when the target variable exceeds the actual variable by a predeterminable first threshold value.

As a further condition for the existence of the second operating state, it can be provided that the absolute amount of the actual quantity exceeds a predeterminable second threshold value. In this way, false tripping can be effectively avoided.

In an advantageous embodiment of the invention, the driver of the vehicle specifies an accelerator pedal value which represents the position of the accelerator pedal by means of an accelerator pedal which he can actuate. As already explained above, a further target variable is determined from the accelerator pedal size by means of a non-linear first map from the accelerator pedal size. This further variable represents, for example, the propulsion request that can be specified by the driver.

During the activation of the ACC system, a virtual accelerator pedal value is determined by means of a second map from the target variable emanating from the ACC system. During the non-activation of the ACC system, a virtual accelerator pedal value is determined using the second map from the further target variable (driver's request for propulsion). The second map can be designed inversely to the first map, but it can also be provided that the actual accelerator pedal angle is taken directly.

The gear ratio is set as a function of the inverse accelerator pedal value, the restriction according to the invention being effected by limiting the inverse accelerator pedal value. Further advantageous embodiments of the invention can be found in the subclaims.

drawing

FIG. 1 shows a control loop of a system for adaptive distance and / or vehicle speed control as is known from the prior art, for example from SAE paper 961010. FIG. 2 shows a detailed exemplary embodiment of the invention on the basis of a block diagram.

Description of exemplary embodiments

FIG. 1 shows an adaptive distance and / or vehicle speed control for a motor vehicle, as is known from the prior art. A central control unit 10 (ACC controller, ACC control unit) represents the central point of the control. The control unit 10 is transmitted by a radar sensor 11 speed and distance data of vehicles driving ahead. The radar system 11 shown here is based on high-frequency microwave radiation, but can alternatively also be embodied as a LIDAR (Light Detection and Ranging) or infrared sensor. With regard to radar technology, the method according to the invention is not limited to an FMCW radar described in SAE paper 961010, but can also be used in connection with, for example, a system operating on the pulse radar principle. The speed data transmitted by the radar unit 11 to the control unit 10 of preceding vehicles (and also other detected objects, for example objects standing at the roadside) are relative speed values related to the speed of your own vehicle. Furthermore, the control unit 10 receives signals from the driver 12 of the motor vehicle. These signals can be, for example, accelerator pedal positions, brake interventions, steering movements, but also operating functions for the ACC system. From the data supplied by the driver 12 and the radar unit 11, the control unit 10 determines an acceleration request that is transmitted to a longitudinal control unit 13 (longitudinal control, LOC). The longitudinal control unit 13 has the purpose of converting the acceleration request transmitted by the control unit 10 into corresponding control signals for the drive / brake control

14 to implement with the appropriate actuators. Actuators 14 can generally be accelerating or decelerating means. For example, a throttle valve control would be conceivable as an accelerating means, while an intervention in the (active) braking system can be regarded as a decelerating means. According to the

Activation of the actuators 14 results in a corresponding driving behavior of the vehicle 15. An engine output torque or a braking torque can also be provided as the output signal of the series regulator. In this case, the acceleration or deceleration requests in the controller 13 are converted into corresponding target moments.

The current vehicle status data is from the vehicle

15 transmitted to the control unit 10. This feedback of the current vehicle data completes the control loop consisting of control unit 10, longitudinal control unit 13, drive / brake control 14 and vehicle 15.

FIG. 2 shows a detailed exemplary embodiment of the invention on the basis of a block diagram. The driver of the vehicle specifies his desire to propel through the position α of the accelerator pedal 24. Starting from the accelerator pedal angle α, a target variable M for the engine output torque is determined in block 25 using a non-linear map. For this purpose, a torque value M is assigned to each value α up to the maximum position α _max by means of the characteristic diagram shown as an example in block 25.

In addition, a torque setpoint M ^ cc is formed by the longitudinal control unit 21 described in FIG. 1 for vehicle speed or distance control.

Depending on the position of the switch 31 (switching signal S1), the motor or the motor controller 26 is now acted upon either with the target variable ^ _QQ during activation of the ACC system or with the target variable M outside of ACC operation. Depending on the operation, the actuators of the motor are controlled in such a way that the desired torque is achieved. The switching signal S1 is formed in the ACC system 21 in this exemplary embodiment. The driver generally determines whether the ACC system is activated by actuating switching means provided for this purpose or by a specific actuation of the accelerator pedal 24.

The setting of the transmission ratio ig _{e of} the transmission 31 is described below.

Depending on the activation of the ACC system (switching signal S1), either the setpoint torque M specified by the accelerator pedal or the setpoint torque M ^ cc specified by the ACC system is sent to block 23 via switch 22.

A map is stored in block 23, which is inverse to the map shown in block 25. So every moment tenwert, depending on the position of the switch 22 M or M ^ c _C 'an inverse accelerator pedal angle α_ assigned.

Depending on the inverse accelerator pedal angle α- _j _ or depending on the limited inverse accelerator pedal angle a ^ (formation in block 27 to be described below), the gear ratio i _ge is determined in block 30 by means of a map. The longitudinal vehicle speed V is also used to determine the gear ratio i _ge . Depending on the value i _ge , the corresponding gear ratio is set in the gear 31.

The maximum value α _max for the accelerator pedal deflection and the 80% value of the maximum deflection are shown in the map schematically shown in block 23. To the associated torque values in the maximum range can be seen the above-mentioned effect, that in the region of the maximum torque of the motor even a small change of the target torque (M or ACC) ^{TO e} αj_ leads i ^nem big jump in the inverse accelerator pedal value. If the transmission ratio i _{ge were to be determined} in block 30 as a function of the inverse accelerator pedal value αj_, then with only small torque changes in the range of the maximum torque or the maximum deflection oc _{max would} lead to unnecessary downshifts in the transmission.

For this reason, in ACC normal operation, the inverse accelerator pedal values αi are limited in block 27, for example to values up to 80% of the full deflection a _max .

The position of the switch 28, which is determined by the switching signal S2, now indicates whether the restricted inverse driving pedal value α ^ _j -, (ACC normal operation) or the unrestricted inverse accelerator pedal value α- _j _ is supplied to block 30.

For the determination of the switching signal S2 is supplied to the block 29, the current actual torque M _j _ _s - _(-.. The vehicle engine supplied This is generally in the motor controller 26 before addition, the block 29, the target torque M _A ££ supplied by the ACC system 21.

In normal ACC operation, the switch 28 is in the position shown in FIG. 2 with a solid line. This limits the inverse accelerator pedal value.

The switch signal S2 can be used to move the switch 28 into the position shown with a broken line in FIG. 2, if at least the torque difference

ΔM = M _ACC - M _is

exceeds a predeterminable threshold value SW1. In this case, the torque M ^ _QQ required by the ACC system deviates substantially from the moment M _j _ _s - ₍ - which is currently being realized, since the maximum torque has been reached at this operating point of the engine.

A further criterion for the switching position of the switch 28 shown in an interrupted manner is the value Mj_ _s - (- of the engine torque M ^ _g - ^ which is currently being realized. If M _j _ _st exceeds a predefinable threshold value SW2 which is close to the maximum torque, the system is located precisely in the area in which small changes in the target torque M _AQ lead to a large jump in the inverse accelerator pedal value αj_ and thus possibly to downshifts. The limitation of the inverse accelerator pedal angle αi in block 27 is avoided if the following conditions exist:

ΔM> SW1 and

M _is > SW2,

the second condition is only optional. Otherwise the inverse accelerator pedal value is limited.

This avoids unnecessary and uncomfortable downshifts during ACC operation, without having to do without the high acceleration that may be required.

The invention does not require any changes to the shift strategy (shifting according to the accelerator pedal angle) and no changes or adjustments to the engine control software.

Claims

Expectations

1. A method for setting a gear ratio of a transmission (31) installed in the drive train of a motor vehicle during the activation of a distance and / or driving speed setting system (21), a target being activated during the activation of the distance and / or driving speed setting system - Size (M _A ) is specified, depending on the at least the drive motor (26) of the vehicle is controlled, wherein

- in case of a first operating state (normal ACC operation), the setpoint value (M _{A (-JC)} ^{or e} i ^{n on} the desired size derived value (α-j_) is limited, and the setting (i _ge) the translation is carried out depending on the limited target size or depending on the limited value (ot k) and

- If there is a second operating state, the setting (ig _e ) of the gear ratio is made depending on the target variable (M _AQ ) or depending on the value (α- _j _).

2. The method according to claim 1, characterized in that the target variable (M _AQQ ) represents a target value for the output _torque or the output power of the vehicle engine (26) and - An actual quantity (M _j _ _st _) representing the current output torque or the current output power of the vehicle engine (26) is determined and

- The second operating state is when the actual size deviates from the target size in a predeterminable manner, it being provided in particular that the second operating state is when the target size is the actual size by a predeterminable first threshold value (SW1 ) exceeds.

3. The method according to claim 2, characterized in that the second operating state is present when the absolute value of the actual size continues to exceed a predeterminable second threshold value (SW2).

4. The method according to claim 1, characterized in that

- The driver of the vehicle specifies an accelerator pedal value (α) representing the position of the accelerator pedal (24) by means of an accelerator pedal (24) that can be actuated by him and

- A further target variable (M) is determined from the accelerator pedal size (α) by means of a non-linear first map (25) and

- A virtual accelerator pedal value (α-j_) by means of a second map (23)

- During the activation of the distance and / or driving speed setting system (21) from the target size (M _AQ ) and

- is determined from the further setpoint variable (M) during the non-activation of the distance and / or vehicle speed setting system (21), the second map (23) being designed inversely to the first map (25), and

- The setting (30) of the gear ratio is made depending on the virtual accelerator pedal value (OC_), and - The restriction is done by limiting the inverse accelerator pedal value (α-j.

5. Device for setting a translation of a gearbox installed in the drive train of a motor vehicle

(31) during the activation of a distance and / or vehicle speed setting system (21), a target variable (M _AQ Γ _, ) being predetermined during the activation of the distance and / or vehicle speed setting system, depending on the at least the Drive motor (26) of the vehicle is controlled, means (29, 30, 31) being provided by means of the

- In the presence of a first operating state (normal ACC operation) the target variable (M _A p_c) or a value derived from the target variable (αj_) is limited and the setting (ig _e ) of the gear ratio depends on the restricted target -Size or depending on the limited value (oo ^] - ₎ ) and

- If there is a second operating state, the setting (ige) of the gear ratio is made depending on the target variable ( ^M _ACC ) or depending on the value (ct-j_).

6. The device according to claim 5, characterized in that the target variable (M _AQ ) represents a target value for the output torque or the output power of the vehicle engine (26) and further means (26, 29) are provided,

- By means of which an actual variable (^ st) representing the instantaneous output torque or the instantaneous output power of the vehicle engine (26) is determined and

by means of which the presence of the second operating state is detected when the actual size deviates from the target size in a predeterminable manner, it being provided in particular that the second operating state is present, if the target size exceeds the actual size by a predeterminable first threshold value (SW1).

7. The device according to claim 6, characterized in that the second operating state is present when the absolute amount of the actual size continues to exceed a predeterminable second threshold value (SW2).

8. The device according to claim 5, characterized in that the driver of the vehicle prescribes an accelerator pedal value (α) representing the position of the accelerator pedal (24) by means of an accelerator pedal (24) which can be actuated by him and further means (25, 23) are provided by means of the

- A further target variable (M) is determined from the accelerator pedal size (α) by means of a non-linear first map and

- A virtual accelerator pedal value (ctj_) by means of a second map

- During the activation of the distance and / or driving speed setting system (21) from the target size

- is determined from the further setpoint variable (M) during the non-activation of the distance and / or driving speed setting system (21), the second map (23) being designed inversely to the first map (25), and

- Setting means (30, 31) are provided, by means of which the setting (30) of the gear ratio is made as a function of the virtual accelerator pedal value (α_), and

- Restriction means (28, 27) are provided, by means of which the restriction takes place by limiting the inverse accelerator pedal value (α-j_).