METHOD FOR CONTROLLING AN AUTOMATIC TRANSMISSION IN A MOTOR VEHICLE

Abstract

One aspect of the invention relates to a method (100) for controlling an automatic transmission (2) of a vehicle (1) equipped with an internal combustion engine (3) and a cruise control system (4), when the vehicle (1) is in motion. The method (100) comprises the steps, executed by control means (5) of the vehicle (1), of: Determining (101) a first acceleration to be applied to the vehicle (1) as a function of the vehicle's speed (1) and a speed setpoint; Determining (102) at least one force applied to the vehicle (1); The method (100) is notable in that when the determined at least one applied force exceeds a threshold value, it includes a step of determining (103) a second acceleration to be applied to the vehicle (1), the second acceleration being less than the first acceleration. Figure 1

Description

Title of the invention: METHOD FOR CONTROLLING AN AUTOMATIC TRANSMISSION OF A MOTOR VEHICLE

[0001] The present invention relates to a method for controlling an automatic transmission in a motor vehicle equipped with an internal combustion engine and cruise control. The invention thus concerns the technical field of automatic transmission control.

[0002] Many vehicles equipped with an internal combustion engine are fitted with a speed regulator arranged to achieve or maintain a pre-programmed vehicle speed by acting on the wheel torque, or the crankshaft torque, in combination with the selection of a gearbox ratio.

[0003] More specifically, the cruise control function selects the gear ratio based on the measured vehicle speed, the speed setting provided by the driver, and the road gradient. This gear ratio selection thus ensures excellent performance.

[0004] In order to achieve the acceleration desired by the driver, when the vehicle is going uphill, the torque demand exerted by the cruise control function is very high. Consequently, it is common for the cruise control function to shift the gearbox from the current gear n to a lower gear n-1. This shift from gear n to a lower gear n-1 results in an increase in the internal combustion engine speed, which in turn leads to an increase in noise perceptible to the vehicle's occupants.

[0005] A control system for hybrid vehicles that optimizes the transition between electric and boost modes, taking into account the road gradient, is also known from document EP-B1-2928745. When a sufficiently steep uphill slope is detected upstream, the system anticipates the need to provide more torque to maintain the vehicle's speed and starts the combustion engine before reaching that slope.

[0006] The use of the internal combustion engine also generates an increase in noise perceptible to the occupants of the vehicle.

[0007] The invention offers a solution to the problems mentioned above, by proposing a method for controlling an automatic gearbox of a motor vehicle equipped with an internal combustion engine to improve occupant comfort.

[0008] In this context, the invention, in its broadest sense, relates to a method for controlling an automatic transmission of a vehicle equipped with an internal combustion engine and cruise control, when the vehicle is in motion. The method comprises the steps, executed by vehicle control means, of: • Determine an initial acceleration to be applied to the vehicle as a function of the vehicle's speed and a speed instruction; • Determine at least one force applied to the vehicle; • The said method is remarkable in that, when the at least one determined applied force is greater than a threshold value, it includes a step of determining a second acceleration to be applied to the vehicle, said second acceleration being less than the first acceleration, • Control said second acceleration of the vehicle.

[0009] In other words, unlike prior art methods, the method according to this aspect of the invention allows for a lower acceleration requirement, and therefore less torque, when it is detected that the vehicle is heavily loaded and / or towing a trailer and / or going uphill. In these problematic situations, the gearbox does not downshift, so the engine speed is not too high and the noise in the passenger compartment is kept down. Thus, limiting gear changes improves the comfort of the vehicle's occupants.

[0010] In addition to the characteristics just mentioned in the preceding paragraph, the process according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.

[0011] According to a non-limiting aspect of the invention, the second acceleration is determined so that the selected gearbox ratio is maintained.

[0012] According to a non-limiting aspect of the invention, the first acceleration to be applied to the vehicle is determined by means of a first mapping providing first acceleration values ​​as a function of vehicle travel speed values ​​and speed instructions.

[0013] According to a non-limiting aspect of the invention, the second acceleration to be applied to the vehicle is determined by means of a second map providing values ​​of second acceleration as a function of values ​​of first acceleration to be applied to the vehicle and values ​​of force applied to the vehicle.

[0014] According to a non-limiting aspect of the invention, the at least one effort applied to the vehicle is a function of the mass of the vehicle.

[0015] According to a non-limiting aspect of the invention, the at least one effort applied to the vehicle is a function of the inclination of the vehicle with respect to the axis of gravity of the vehicle.

[0016] According to a non-limiting aspect of the invention, at least one effort applied to the vehicle is a function of at least one aerodynamic force.

[0017] Another aspect of the invention relates to a computer program product downloadable from a communication network and / or recorded on a computer-readable medium and / or executable by a processor, characterized in that it includes program code instructions for implementing the method according to any one of the aforementioned aspects of the invention, when the program is executed on a computer.

[0018] A different aspect of the invention relates to a motor vehicle equipped with an automatic gearbox, an internal combustion engine, a speed regulator and control means, said vehicle being remarkable in that said control means are constructed and arranged to carry out the steps of the process according to any one of the aforementioned aspects of the invention.

[0019] According to a non-limiting aspect of the invention, the control means are formed by motor control unit.

[0020] The invention and its various applications will be better understood by reading the following description and examining the accompanying figure.

[0021] [Fig-1] illustrates a schematic view of a motor vehicle according to the invention arranged to execute a process according to the invention.

[0022] More particularly, [Fig.1] schematically illustrates a motor vehicle 1 according to the invention arranged to perform a method 100 of controlling an automatic gearbox of the vehicle according to the invention.

[0023] Vehicle 1 includes, in particular: • A 2-speed automatic gearbox; • An internal combustion engine 3; • A 4-speed cruise control; and • Means of control 5.

[0024] The control means 5 are constructed and arranged to carry out the steps of the process 100 according to the invention.

[0025] By way of non-limitation, these control means may be formed by a motor control unit (better known by the acronym MCU for Motor Control Unit in English).

[0026] When vehicle 1 is in motion, the method 100 includes a step of determining 101 a first acceleration to be applied to vehicle 1. This first acceleration is determined as a function of the vehicle's speed of movement 1 and a speed setpoint.

[0027] By way of non-limitation, the speed of movement of vehicle 1 can be determined by a speed sensor included in the vehicle, said speed sensor being sensitive to the rotation of the axle of a wheel of vehicle 1. The determined speed of movement can then be transmitted from this sensor to the control means 5.

[0028] As for the speed instruction, this can be entered by the driver via a human-machine interface and then transmitted to the control means 5.

[0029] According to a non-limiting example, this first acceleration to be applied to vehicle 1 is determined by means of a first mapping providing first acceleration values ​​as a function of vehicle 1's speed values ​​and speed instructions.

[0030] In other words, by transferring the speed of movement of vehicle 1 and the speed command into this first map, the first map provides a first acceleration to be applied to vehicle 1.

[0031] The method 100 also includes a step of determining 102 at least one force applied to the vehicle 1.

[0032] The force applied to vehicle 1 can be a function of the vehicle's mass. Indeed, the mass of vehicle 1 will be modified if vehicle 1 is loaded and / or if it is towing a trailer. Such a load can, for example, be detected by the control means 5 when the trailer is electrically connected to vehicle 1.

[0033] This force applied to vehicle 1 can also be a function of the vehicle 1's inclination relative to its axis of gravity. Indeed, the forces applied to vehicle 1 will differ when vehicle 1 is moving on a flat road or when vehicle 1 is moving uphill. By way of example, this incline can be detected by the control means 5 when, for the same engine speed and the same gear engaged, the speed of vehicle 1 decreases.

[0034] This effort applied to vehicle 1 can also be a function of at least one aerodynamic force.

[0035] It is understood that according to other embodiments, the at least one force applied to the determined vehicle 1 may be chosen by one or formed by a combination of: • The mass of vehicle 1; • The inclination of vehicle 1; • At least one aerodynamic force.

[0036] When the at least one determined applied force is greater than a threshold value, the method 100 includes a step of determining 103 a second acceleration at apply to vehicle 1. According to the invention, the second acceleration is less than the first acceleration.

[0037] According to one aspect of the invention, the second acceleration is determined so that the selected gearbox ratio is maintained. In other words, thanks to the method according to the invention, there is no change in gearbox ratio 2.

[0038] According to one embodiment, the second acceleration to be applied to vehicle 1 is determined by means of a second map providing values ​​of second acceleration as a function of values ​​of first acceleration to be applied to vehicle 1 and values ​​of force applied to vehicle 1.

[0039] In other words, depending on the first acceleration determined during step 101 and the at least one effort applied to vehicle 1 determined, the second mapping provides a second acceleration to be applied to vehicle 1, the second acceleration being less than the first acceleration determined during step 101.

[0040] In other words, compared to prior art methods, method 100 according to this aspect of the invention makes it possible to request less acceleration, and therefore a lower engine speed, when it is detected that the vehicle is loaded and / or towing a trailer and / or moving uphill. By avoiding a gear change in the gearbox 2 and an increase in the speed of the internal combustion engine 3, method 100 avoids a jolt associated with the gear change in the gearbox 2 as well as an increase in noise in the passenger compartment. The comfort of the occupants of vehicle 1 is thus improved.

[0041] The method 100 then performs a step of controlling 104 the second acceleration of the vehicle 101 in accordance with the second acceleration of the vehicle 1 determined. To do this, the control means 5 act on the torque of the internal combustion engine 3.

Claims

Demands

1. A method (100) for controlling an automatic gearbox (2) of a vehicle (1) equipped with an internal combustion engine (3) and a cruise control (4), when said vehicle (1) is in motion, said method (100) comprises the steps, executed by control means (5) of said vehicle (1), of: - Determining (101) a first acceleration to be applied to said vehicle (1) as a function of a speed of said vehicle (1) and a speed setpoint; - Determining (102) at least one force applied to said vehicle (1); - Said method (100) being characterized in that it comprises the steps of: • When said at least one determined applied force is greater than a threshold value, determining (103) a second acceleration to be applied to said vehicle (1), said second acceleration being less than said first acceleration; • Controlling (104) said second acceleration of said vehicle (1).

2. Method (100) according to the preceding claim, characterized in that the second acceleration is determined so that the selected automatic gearbox ratio (2) is retained.

3. Method (100) according to any one of the preceding claims, characterized in that the second acceleration to be applied to the vehicle (1) is determined by means of a second mapping providing values ​​of second acceleration as a function of values ​​of first acceleration to be applied to the vehicle (1) and values ​​of force applied to the vehicle (1).

4. Method (100) according to any one of the preceding claims, characterized in that the first acceleration to be applied to the vehicle (1) is determined by means of a first mapping providing first acceleration values ​​as a function of vehicle (1) travel speed values ​​and speed instructions.

5. Method (100) according to any one of the preceding claims, characterized in that the at least one force applied to the vehicle (1) is a function of the mass of said vehicle (1).

6. Method (100) according to any one of the preceding claims, characterized in that the at least one force applied to the vehicle (1) is a function of an inclination of said vehicle (1) with respect to the axis of gravity of said vehicle (1).

7. Method (100) according to any one of the preceding claims, characterized in that the at least one effort applied to the vehicle (1) is a function of at least one aerodynamic force.

8. Product computer program downloadable from a communication network and / or recorded on a computer-readable medium and / or executable by a processor, characterized in that it includes program code instructions for implementing the method (100) according to any one of the preceding claims, when the program is executed on a computer.

9. Motor vehicle (1) equipped with an automatic gearbox (2), an internal combustion engine (3), a speed regulator (4) and control means (5), said vehicle (1) being characterized in that said control means (5) are constructed and arranged to carry out the steps of the process (100) according to any one of claims 1 to 7.

10. Vehicle (1) according to the preceding claim, characterized in that the control means (5) are formed by motor control unit.