FR2850725A1 - Gear box control system for vehicle, has analyzing unit to confirm or invalidate desired ratio before delivering orders corresponding to control gear box for engaging only desired ratio which have been confirmed - Google Patents

Abstract

The system has an information acquisition unit to acquire information relating to functioning of an engine of a vehicle and conditions of movement of the vehicle. An analyzing unit (12) analyzes the information to determine a desired ratio of a gear box to be engaged. The unit (12) confirms or invalidates the ratio before delivering orders corresponding to control the box for engaging only the ratio which have been confirmed. Independent claims are also included for the following: (a) a control process of a gear box of a vehicle (b) an information recording medium with instructions to perform a method to control a gear box.

Description

i

  The invention relates to a system and method for controlling a gearbox of a motor vehicle. It also relates to an information recording medium containing instructions for the execution of the method.

  Such systems have already been disclosed in French patent application FR-A-2 795 796. These known systems include: - means for acquiring information relating to the conditions of movement of the vehicle; means of acquiring information relating to the operating conditions of the vehicle engine; - means of acquiring information relating to the driving of the vehicle by the driver; a clutch / disengage pedal allowing the driver of the vehicle to adjust the clutch / disengage level of the clutch mechanism; - means for detecting the depression of this clutch / disengage pedal by the driver; and - means for analyzing the acquired information able, in response to the detection of the depressing of the clutch / disengaging pedal, to: - establish, using different analysis criteria, vectors of information representative of the driver's desire to change the gearbox, each analysis criterion providing an information vector comprising at least one decision variable defining desired gear change information and one variable degree of confidence in this decision; - determine a new gearbox report to be engaged from the established information vectors; and issue corresponding control orders to the gearbox to initiate this report.

  The result of the determination of a new gear ratio using information vectors is always either to increase or to decrease the gear ratio but is never zero, i.e. that the result is never to keep the same gear ratio as the previous one.

  Therefore, in known systems, each time the driver depresses the clutch pedal, a new gearbox ratio is engaged.

  It has been noted that when using such systems, it happens that the driver, following a wrong maneuver, accidentally depresses the clutch pedal. Under these conditions, the new gearbox gear engaged is often inappropriate with respect to the conditions of movement of the motor vehicle and / or of operation of the engine. For example, following an accidental depressing of the clutch pedal, a lower gearbox ratio is engaged while the speed of movement of the vehicle is too high for such an operation or vice versa.

  The invention aims to remedy this drawback by proposing a system for controlling a gearbox of a motor vehicle in which inappropriate maneuvers for changing the gearbox ratio are avoided.

  The invention therefore relates to a system for controlling a gearbox of a motor vehicle, as described above, characterized in that after having determined a candidate report, the analysis means are able to confirm or invalidate the candidate report using the information acquired, before issuing corresponding gearbox control orders to engage only candidate reports which have been confirmed.

  In the above system, the analysis means check whether the new gearbox ratio determined using the information vectors is appropriate to the conditions of movement of the motor vehicle and / or to the operating conditions of the engine.

  It is only in the case where the new gearbox report is considered to be appropriate that the system issues control commands to the gearbox to engage this new report.

  Otherwise, i.e. if the new gear is considered inappropriate, then the transmission control is inhibited and the current gear ratio is not changed.

  According to other characteristics of a system according to the invention: the analysis means are capable of executing a state graph to confirm or invalidate said candidate report; the analysis means are able to compare the speed acquired from the motor vehicle with a predetermined speed threshold to confirm or invalidate a candidate report; the system comprises a clutch / disengage mechanism of the motor vehicle controllable by the analysis means and the analysis means are able to: - detect a situation of engine under-speed when the current gearbox ratio is too high with respect to the conditions of movement of the motor vehicle acquired, and - in response, automatically issuing corresponding control orders both from the gearbox and to the clutch / disengage mechanism to engage a lower gear ratio.

  - the analysis means are capable of: - detecting a situation in which the engine of the motor vehicle risks stalling, and - in response, automatically issuing corresponding control commands to the gearbox to shift to neutral in the gearbox speeds; the analysis means are capable of automatically issuing control commands to the gearbox to shift into neutral if, simultaneously, the brake pedal is depressed, the current gearbox ratio engaged is the smallest and if the clutch / disengage mechanism is in the engaged position; - the analysis means are able to determine said candidate report by implementing the theory of possibilities.

  The invention also relates to a method for controlling a gearbox of a motor vehicle comprising a step of acquiring information relating to the operation of the engine of the motor vehicle, to the conditions of movement of the motor vehicle and / or the conditions under which the driver drives the vehicle; and - a step of analyzing the acquired information suitable for: - establishing, using different analysis criteria, information vectors representative of the driver's desire to change the gearbox ratio, each analysis criterion providing an information vector comprising at least one decision variable defining a desired gear change information and a confidence degree variable relating to this decision; - determine a gearbox candidate report to be engaged from the established information vectors, characterized in that after having determined a candidate report, the analysis means confirm or invalidate the candidate report using the information acquired , before issuing corresponding gearbox control orders to engage only candidate reports that have been confirmed.

  According to other characteristics of the control method according to the invention: - it comprises the steps consisting in: - detecting a situation of engine under-speed when the current gearbox ratio is too high compared to the conditions of movement of the acquired motor vehicle, and - in response, automatically issuing corresponding control commands both to the gearbox and to the clutch mechanism to engage a lower gear ratio; - The method includes the steps of: - detecting a situation in which the motor vehicle engine risks stalling, and - in response, automatically issuing corresponding control commands to the gearbox to shift to neutral of the gearbox speeds.

  The subject of the invention is also an information recording medium comprising instructions for the execution of a method of controlling a gearbox of a motor vehicle according to the invention when said instructions are executed by an electronic computer.

  The invention will be better understood on reading the description which follows, given solely by way of example and made with reference to the drawings in which: - Figure 1 is a schematic view of the architecture of a system 10 for controlling a gearbox according to the invention; - Figure 2 is a flow diagram of a method for controlling a mechanical gearbox according to the invention; and FIG. 3 is an illustration of a state graph used during the execution of the method of FIG. 2.

  FIG. 1 represents a motor vehicle 2 equipped with a mechanical gearbox 4 and a clutch / disengage mechanism 6 associated with this gearbox. This vehicle 2 is also equipped with a control system for the gearbox 4 and the clutch / disengage mechanism 6, designated by the general reference 10.

  The gearbox 4 is here for example a mechanical gearbox with five ratios respectively numbered in ascending order of the gear ratios from 1 to 5. The ratio 1 corresponds to the smallest gear ratio while the ratio 5 corresponds to the greater gear ratio. The neutral position of the gearbox 4 is designated by 0.

  The clutch / disengage mechanism is controllable both manually by the driver using a clutch pedal 8 and automatically by the system 10. When the pedal 8 is depressed, the clutch mechanism is in a disengaged position while when the pedal 8 is at rest, the clutch mechanism 6 is in a engaged position.

  The system 10 comprises means for acquiring information connected to an input of an electronic computer 12 suitable for controlling, as a function of the information acquired, means 14 for actuating the gearbox 4 and the clutch mechanism / declutching 6. The actuating means 14 are capable of engaging an upward or downward gearbox ratio under the control of the computer 12.

  To this end, the computer 12 is a programmable computer produced in a conventional manner and suitable for executing instructions recorded on an information recording medium 16. These instructions are arranged so that the computer performs the method described with reference to FIG. 2 when it executes them. In the embodiment described here, this information recording medium 16 also forms means 10 for storing information for the different coefficients and parameters necessary for the execution of the method of FIG. 2.

  The information acquisition means here comprise - means 20 for acquiring information on the conditions of movement of the motor vehicle including, in particular, a sensor 22 15 for acquiring the speed of the vehicle 2 and a module 23 calculating the acceleration of the vehicle 2 from information acquired on the speed and implemented in the computer 12; means 24 for acquiring information on the operating conditions of the vehicle engine; and means 26 for acquiring information relating to the behavior of the driver.

  More specifically, the means 24 for acquiring information relating to the engine operating conditions here comprise a sensor 30 of the torque developed by the drive wheel drive shaft of the vehicle, and a sensor 32 of the angular speed of that same tree.

  The means 26 for acquiring information relating to the behavior of the driver comprise a detector 34 for depressing the pedal 8. This pedal 8 therefore forms here, in addition to a conventional mechanical actuation means of the clutch mechanism 6, a clutch release button 30 allowing the driver of the motor vehicle to indicate when he depresses this pedal that he wishes to change the gearbox ratio.

  The means 26 also comprise a detector 38 of the position of a brake pedal 40 and a lever 41 for controlling the movement of the vehicle 2.

  The detector 38 is capable of indicating to the computer 12 that the driver wishes to slow down the vehicle 2.

  The control lever 41 can be moved under the driver's control between three positions, respectively a front position, a neutral position and a rear position. These forward, neutral, reverse positions correspond to the wishes of the driver, respectively, to initiate an upshift gearbox, to shift into neutral, or to engage a reverse gearbox. Thus, this lever 41 allows the driver to start, stop the vehicle or even move the vehicle in reverse. However, only the pedal 8 allows the driver to indicate that he wishes to change the gear ratio when the vehicle is traveling in forward gear.

  The brake pedal 40 is capable of actuating a device 42 for braking the motor vehicle 2.

  Finally, the system 10 also includes means 44 for acquiring the current or currently engaged ratio of the 20-speed gearbox4. The means 44 are connected to the gearbox 4 and to the computer 12.

  The operation of the system 10 will now be described with reference to FIGS. 2 and 3.

  After the vehicle 2 has been started, all of the elements of the system 10 are supplied and activated. The computer 12 then performs an initialization step during which it controls the means 14 for actuating the gearbox 4 to automatically shift to neutral.

  From this moment and permanently, the computer 12, in step 62, acquires all of the information collected and delivered by the 30 different acquisition means of the system 10.

  Then, in step 64, it checks whether the gearbox ratio currently engaged is strictly greater than the number 1 gear. If so, the computer 12 establishes, in step 68, information vectors and in step 70, merge these information vectors to determine a gearbox candidate report.

  For more details on these steps, the reader can refer to the French patent application FR-A-2 795 796 mentioned previously. It is simply recalled here that the information vectors are established using predetermined analysis criteria and as a function of the information acquired during step 62.

  These steps 68 and 70 are performed in accordance with probability calculations known as "possibility theories".

  At the end of step 70, the computer 12 proceeds to a step 72 of supervision.

  In the case where during step 64, the computer determines that the report currently engaged is report number 1, it proceeds directly to step 72 of supervision without performing steps 68 and 70.

  During step 72, the computer 12 executes the state graph represented in FIG. 3 so as to: - initiate a new report in response to the depressing by the driver of the pedal 8 only if this new report is appropriate to the conditions of movement of the vehicle 2 and to the operating conditions of the engine, - automatically engage a downshift when the engine is running at low speed, and automatically shift to neutral of the gearbox when the engine of the vehicle 2 risks stalling.

  At the end of step 72, the computer returns to step 62.

  The state graph in Figure 3 is for illustration only and has been simplified. Indeed, each state represented in this graph can be broken down into several sub-states not represented.

  Conventionally, a state graph is made up of states linked together by transitions. The computer 12 goes from one state to another only when the transition between these two states is activated or validated, that is to say for example here, when the Boolean condition associated with this transition is evaluated to be true. When two states are separated by an always activated transition, that is to say that two states are linked automatically and systematically, this transition is not represented in FIG. 3.

  In the state graph in Figure 3, three variables Rv, Rc and RE are used.

  Rv is intended to store an integer value corresponding to the number of the gearbox report targeted or to be engaged.

  The variable Rc is intended to store an integer corresponding to the gearbox report number determined during step 70.

  The variable RE is intended to store an integer corresponding to the gearbox ratio currently engaged. The variable RE is automatically updated from the information delivered by the means 44 for acquiring the current report.

  Initially, in state 80, the gearbox is in neutral. A transition 82 from state 80 to state 84 is activated if the following three conditions are simultaneously met: - the lever 41 is in its front position, - the pedal 8 is depressed, and - the speed of the vehicle 2 is less than a pre-recorded and constant VMAX STOP threshold.

  The value of the VMAX STOP threshold is for example 3 km / h.

  In state 84, the computer 12 controls the means 14 for actuating the gearbox 4 to engage the gear number 1 if the value of RE is not already equal to 1. The advantage of this latter condition will appear on reading the following description.

  In the case where the driver actuates the lever 41 to return it to its neutral position, while at the same time the speed of the vehicle 2 is lower than the VMAX STOP threshold, then a transition 86 from state 84 to state 30 80 is activated.

  In the case where the brake pedal 40 is depressed while simultaneously the clutch pedal 8 is released or in its rest position, a transition 88 from state 84 to state 90 is activated.

  In state 90, the computer 12 controls the clutch mechanism 6 to automatically move it to its disengaged position and then controls the actuating means 14 to automatically shift into neutral.

  As soon as the value of the variable RE is equal to 0, a transition 92 between state 90 and state 80 is activated.

  Thus, when the gear number 1 is engaged and the driver brakes without disengaging, the system 10 disengages automatically and shifts to neutral so as to prevent the engine of the vehicle 2 from stalling.

  A transition 94 from state 84 to state 96 is activated as soon as the following three conditions are simultaneously satisfied - the clutch pedal 8 is depressed, - the speed of vehicle 2 is greater than a predetermined and constant threshold V2-5 , and - the value of the variable Rc, established during step 70, is strictly greater than 1.

  The value of the threshold V2-5 is for example 14 km / h.

  In state 96, the computer 12 assigns the value of the variable RC to the variable Rv, then automatically switches to a state 97. In state 97, the computer 12 controls the actuating means 14 to engage the report of speeds corresponding to the value of the variable Rv.

  Thus, when the vehicle 2 is traveling at an appropriate speed, here greater than 14 km / h, the driver triggers the engagement of a new gear ratio by simply depressing the pedal 8, the new gear ratio to be engaged being meanwhile determined automatically during the merger step.

  If the value of the variable RE is greater than or equal to 2, then a transition 98 from state 97 to state 100 is activated.

  At state 100, the computer continuously checks the operating conditions of the engine and compares them to the conditions of movement of the vehicle to determine whether the engine is running under speed. For this, it compares the conditions of movement of the vehicle, for example the speed, it to the operating conditions of the engine, for example the torque developed by the engine.

  If the engine is running under speed, a transition 102 from state to state 104 is activated.

  In state 104, the computer 12 controls the clutch mechanism 6 to move it to its disengaged position. Simultaneously, it assigns to the variable Rv the value of the variable RE-1.

  As soon as the mechanism 6 is in its disengaged position, a transition 106 from state 104 to state 97 is activated.

  Thus, if the driver brakes without disengaging, the system 10 automatically engages downhill without manual intervention of the driver.

  In state 97, if after having engaged the new gear ratio the value of variable RE is equal to 1, a transition 110 from state 96 to state 84 is activated so that the computer is able to return to state 84.

  Two transitions 112 and 114 are available to go from state to state 96.

  The transition 112 is activated when the pedal 8 is depressed and 20 when the value of the variable Rc established in step 70 is strictly greater than 1.

  The transition 114 is activated as soon as the following three conditions are simultaneously met: - the pedal 8 is depressed, - the value of the variable Rc, established in step 70, is equal to 1, and - the vehicle speed is lower at a threshold V1.

  The constant threshold V1 is for example equal to 14 km / h. Consequently, the driver of the vehicle can engage the gear ratio number 1 only when the conditions of movement of the vehicle are suitable, that is to say here that the speed of vehicle 2 is below the threshold Vi.

  The system 10 described therefore makes it possible to avoid engaging the gear ratio number 1, if the vehicle 2 is moving too quickly. This is particularly useful in the event of accidental depressing of the pedal 8 by the driver.

  In a similar way to what has been described with regard to the transition 114, as a variant, conditions for engaging the gear ratios number 2, 3 5 or higher are associated for example with a transition placed between the state and 96, of so as to authorize the passage of a new gear ratio only when the displacement and / or operating conditions of the engine are appropriate.

  The system has been described here in the particular case where the value of the torque developed by the drive wheel drive shaft is measured by a torque sensor 30. As a variant, this same information is calculated from the data of a fuel injection computer.

  In the system described here, it is the clutch / disengage pedal 8 which acts as a button for activating a gear change of 15 speeds. As a variant, the vehicle is furthermore equipped with a clutch / disengaging pedal, with a button for activating a gear change independent of the clutch / disengaging pedal.

Claims (11)

  1. A control system for a gearbox (4) of a motor vehicle (6), this system comprising: - means (20, 24, 26) for acquiring information relating to the operation of the engine of the motor vehicle, the conditions of movement of the motor vehicle and / or the conditions of driving of the vehicle by the driver; and - means of analysis (12) of the acquired information suitable for: - establishing, using different analysis criteria, vectors 10 of information representative of the driver's desire to change the gear ratio gearbox, each analysis criterion providing an information vector comprising at least one decision variable defining information on the desired gear change and a confidence degree variable relating to this decision; - determine a gearbox candidate report to be engaged from established information vectors, characterized in that after having determined a candidate report, the analysis means are capable of confirming or invalidating the candidate report using the information acquired, before issuing corresponding control commands 20 of the gearbox to engage only candidate reports which have been confirmed.   2. System according to claim 1, characterized in that the analysis means (12) are capable of executing a state graph to confirm or invalidate said candidate report.   3. System according to any one of the preceding claims, characterized in that the analysis means (12) are capable of comparing the speed acquired from the motor vehicle with a predetermined speed threshold to confirm or invalidate a candidate report.   4. System according to any one of the preceding claims, characterized in that it comprises a mechanism (6) for engaging / disengaging the motor vehicle controllable by the analysis means (12) and in that the means for analysis (12) are able to: - detect a situation of engine under-speed when the current gearbox ratio is too high in relation to the traveling conditions of the motor vehicle acquired, and - in response, automatically issue corresponding orders 5 for controlling both the gearbox (4) and the clutch / disengage mechanism (6) to engage a lower gear ratio.   5. System according to any one of the preceding claims, characterized in that the analysis means (12) are capable of: - detecting a situation in which the engine of the motor vehicle risks stalling, and - in response, delivering automatically corresponding control commands to the gearbox (4) to shift to neutral of the gearbox.   6. System according to claim 5, characterized in that the analysis means (12) are capable of automatically issuing control orders to the gearbox (4) to shift to neutral if, simultaneously, the foot pedal brake (40) is depressed, the current gearbox ratio engaged is the smallest and if the clutch / disengage mechanism (6) is in the engaged position.   7. System according to any one of the preceding claims, characterized in that the analysis means (12) are capable of determining said candidate report by implementing the theory of possibilities.   8. A method of controlling a gearbox of a motor vehicle, this method comprising: - a step (62) of acquiring information relating to the operation of the engine of the motor vehicle, to the conditions of movement of the motor vehicle and / or the conditions under which the driver drives the vehicle; and - a step of analyzing the acquired information suitable for: - establishing (at 68), using different analysis criteria, information vectors representative of the driver's desire to change the gear ratio gearbox, each analysis criterion providing a vector of information comprising at least one decision variable defining a desired gear change information and a confidence degree variable relating to this decision - determining (in 70) a candidate gear gearbox to be engaged from established information vectors, characterized in that after having determined a candidate report, the analysis means (12) confirm or invalidate (at 72) the candidate report using the information before issuing corresponding gearbox control orders (4) to engage only candidate reports that have been confirmed.   9. Method according to claim 8, characterized in that it comprises the steps consisting in: - detecting (in 100) a situation of engine under-speed when the current gearbox ratio is too high compared to the displacement conditions of the acquired motor vehicle, and - in response, automatically issuing (at 104) corresponding control commands both from the gearbox and to the clutch mechanism to engage a lower gear ratio.   10. Method according to claim 8 or 9, characterized in that it comprises the steps consisting in: - detecting (at 84, 88) a situation in which the engine of the motor vehicle risks stalling, and - in response, automatically delivering (at 90) of the corresponding control commands to the gearbox (4) to shift to the neutral position of the gearbox.   11. An information recording medium (16) comprising instructions for the execution of a method for controlling a gearbox (4) of a motor vehicle (2) according to any one of claims. 8 to 10 when said instructions are executed by an electronic computer (12).