FR3042002A1 - METHOD FOR CONTROLLING THE OPERATION OF A THERMAL MOTOR OF A VEHICLE - Google Patents

Abstract

The invention relates to a method for controlling the operation of a heat engine (MTH) of a vehicle. The invention is characterized in that the method applies a prohibition of the freezing action (IAF) to increase said depression, when the estimated amount of torque to be taken by the adjustable factor (A1 ... An) when changing the gear ratio is less than the amount of torque taken from the engine by said adjustable factor at the moment of initiation of the gear change, the estimated amount of torque to be taken by said adjustable factor (A1 ... An) being estimated by means of implementing the vehicle method. The invention finds its application in the field of the automotive industry.

Description

The invention relates to a method for controlling the operation of a heat engine of a vehicle, a vacuum in this engine being applied to a vehicle assistance system. hydraulic braking system of the vehicle, the method applying, during a gearshift of the vehicle, an action of freezing, for the pleasure of driving, the amount of torque taken from the engine by an adjustable factor by adjusting this adjustable factor .

The invention also provides a vehicle comprising a heat engine and means for implementing such a method of controlling the operation of the engine.

In order to improve the driving pleasure of a vehicle equipped with a heat engine during gearshift, it is known to freeze losses called accessories. In other words, the computers of the vehicle, during these shifts gear ratios, maintain constant the amount of torque taken from the engine by the vehicle accessories, these accessories being mostly the piloted alternator, the system of air conditioning, electrical accessories. To do this, the engine torque consumption is continuously adjusted by the computers of the vehicle if a freezing action is controlled by these computers.

However, this type of strategy has the disadvantage of sometimes generating too much engine torque consumption compared to the actual need for accessories. The direct consequence is a risk to safety: indeed the engine also has the function, in most vehicles, to generate the necessary vacuum for assistance of the braking system. However, the more accessories draw torque from the engine, the less it is inclined to generate a satisfactory depression for assistance of the braking system.

In FR 1450061, it is known a method of optimizing the operation of a gasoline engine to obtain a sufficient vacuum so as to give a safe braking. To allow the gasoline engine to generate a sufficient vacuum, the method provides either to unload the accessories consuming engine torque, or to increase the engine idling speed, or to reset the position of the camshafts so that it There is more crossing of valves, facilitating the generation of vacuum.

However, none of these strategies is adapted to improve driving pleasure during the passage of gear ratio.

The present invention aims to overcome the above disadvantages of the prior art.

To achieve this goal and in particular to obtain a greater vacuum in the engine applied to an assistance of the hydraulic braking system of the vehicle, the control method according to the invention is characterized in that it applies a prohibition of the freezing action to increase said depression, when the estimated amount of torque to be taken by the adjustable factor during the gear ratio change is less than the amount of torque taken from the engine by said adjustable factor at the moment of initiation of the change of gear. gear ratio, the estimated amount of torque to be taken by said adjustable factor being estimated by means of implementation of the vehicle method.

According to another feature, the prohibition of the freezing action is applied when the estimated amount of torque to be taken from the motor by the adjustable factor decreases during the gear ratio change, and the freezing action is applied when the estimated amount of torque to be taken from the motor by the adjustable factor increases during gearshift.

According to another feature, the prohibition of the freezing action is applied from a detection of a critical vacuum threshold in an amplifier of the assistance of the braking system.

According to another feature, the freezing action is applied from the initiation of the gear ratio change.

According to another feature, the adjustable factor comprises at least one of a rotary machine applying an adjustable load torque on the engine, such as an alternator or an air conditioning compressor.

According to another feature, the freezing action and the estimation of the amount of torque to be taken by the accessories are implemented by a vehicle engine ECU, able to communicate with the engine.

According to another feature, a vehicle communication controller capable of communicating with the gearbox and calculating a moment for initiating a gear ratio change by said gearbox, sends a request for freezing action. to the engine computer when the gearbox sends him a signal relating to the initiation of a change of gears.

According to another feature, the prohibition of the freezing action is sent by the engine computer to the vehicle communication controller during a gear ratio change.

The invention also relates to a motor vehicle having a heat engine producing a vacuum applied to an assistance of the braking system, characterized in that it comprises means for implementing the method of controlling the operation of this system. motor as defined above.

According to another feature, the gearbox of the vehicle is a manual gearbox, a manual gearbox driven, an automatic gearbox with hydraulic converter, a robotized gearbox, a continuously variable transmission or a double clutch transmission.

The invention will be better understood, and other objects, features, details and advantages thereof will appear more clearly in the explanatory description which follows with reference to the accompanying drawings given solely by way of example illustrating a embodiment of the invention and in which: - Figure 1 shows a diagram of the vehicle showing in particular the connection between the engine, the gearbox, the braking system and accessories; FIG. 2 represents three graphs showing, as a function of time, the implementation of a freezing action in response to a gear ratio change; FIG. 3 represents four graphs showing, as a function of time, the implementation of a prohibition of the freezing action when the estimated quantity of torque to be taken by at least one adjustable factor when the gear ratio is changed is less than the amount of torque taken from the engine by said adjustable factor at the moment of initiation of the change of gear ratio; - Figure 4 shows a diagram showing the vehicle elements involved in the implementation of the method according to the invention.

The invention is described below with reference to Figures 1 to 4, applied to a motor vehicle.

In Figure 1 is shown a diagram of a motor vehicle, showing the two trains T1, T2 front and rear wheels, the engine MTH, for example a gasoline engine, the BV gearbox, and two accessories A1, A2 each connected to the motor shaft by a system of belts CO, these two accessories being thus able to take a portion of the torque to the motor MTH for their respective operation.

For example and without limitation, an accessory A1, A2 may be an air conditioning compressor, an alternator, or an electric machine.

The continuous curve 1 of the second graph of Figure 2 illustrates the variation, as a function of time, the estimated amount of torque to be taken from the MTH motor accessories A1, A2 ... An. This estimated amount of torque to be taken is estimated by means of implementation of the vehicle method, and is directly related to the engine speed of the vehicle.

Thus, this estimated amount of torque to be taken to the MTH motor accessories A1 to An over time, and illustrated by the solid curves of the second graph of Figures 2 and 3, is known at each moment. It is clear that this quantity is very variable as a function of time, because it depends on the number of accessories that can work or stop. In other words, the torque taken from the engine by the accessories varies constantly, which can lead to a problem in the driving pleasure, especially when passing a gear ratio by the gearbox BV: indeed, the Starting or stopping one or more accessories during gear changes causes variations in the amount of available engine torque. The driver can feel the effects: pitching of the vehicle, impression of loss of power or, on the contrary, sudden acceleration are all phenomena which impair the driving pleasure, that is to say the behavior of the vehicle as felt by the driver.

In known manner, the implementation means comprise a communication controller TCU and a motor ECU CMM. it is the TCU communication controller included in the vehicle that requests the vehicle's engine control unit CMM to change gear ratio CdR to be initiated by the gearbox BV when necessary. This engine ECM engine, well known to those skilled in the art, allows in particular to adjust the fuel injection for optimal fuel consumption, or to estimate the amount of torque to be taken from the engine by the accessories.

The engine control unit CMM then commands the gearbox BV to initiate the change gear ratio, especially when the engine speed requires such a change. As can be seen in FIG. 4, the communication controller TCU communicates with the gearbox BV. The latter sends to the TCU controller the signal relating to the initiation and the end of a gear shift CdR.

To alleviate this problem of driving pleasure during the gear ratio change, a well known solution for the skilled person consists in generating a freezing action AF of the amount of torque taken from the MTH engine. by the accessories A1 to An, during gear shifts. Because it is possible to control the amount of torque taken by at least one A1 to An accessories, these accessories are also called adjustable factors.

When the gear ratio initiation signal is sent by the gearbox BV to the CMM communication controller of the vehicle, an AF lock request is requested by the communication controller TCU and transmitted by the latter to the engine ECU CMM. The engine control unit CMM then applies this freezing action AF to control the computer or G computers controlling accessories A1 to An, so that the sampling torque to the engine by the accessories A1 to An is constant for the duration of the gear ratio change. CdR speeds. As can be seen in the first and third graphs of FIG. 2, the freezing action AF is active as long as the gear ratio change by the gearbox BV is in progress. The pitching of the vehicle, during gear changes, or any other sensation related to power loss or sudden acceleration, are therefore attenuated.

However, although solving the amenity problem of driving described above, this freezing action AF causes a non-optimal torque consumption.

It can be seen from curves 1, 2 of the second graph of FIG. 2 that the freezing action AF induces at times a greater torque pick-up by the accessories A1 to An than the torque sampling estimated by the engine control unit CMM.

However, under certain conditions, it is necessary to have the maximum torque available to allow the MTH engine to generate enough vacuum to ensure safe braking.

As shown in Figure 1, the vehicle also comprises a braking system. This braking system, connected to the brake pedal P, comprises a vacuum assistance M comprising an amplifier having a sealed housing, also called "Mastervac" and having a diaphragm subjected to a vacuum providing an assistance effort that adds to that applied by the driver.

The amplifier is interposed between the brake pedal P and the hydraulic master cylinder which allows braking via a hydraulic circuit CH, and receives a vacuum D from the engine MTH by a pipe connected to the intake duct. downstream of a throttle opening of the intake gases. The intensity of the vacuum provided by the MTH motor depends directly on the opening of the throttle and the speed of rotation of the MTH engine, as is well known to those skilled in the art.

The skilled person is perfectly aware that when the D depression used by the "Mastervac >> M comes from the MTH engine, the less accessories A1 to An are likely to take torque to the engine, the more the MTH engine is able to generate a sufficient vacuum to guarantee safe braking.

Thus, to maintain a satisfactory driving pleasure when changing gears while ensuring a sufficient vacuum level D to ensure safe braking, a prohibition of freezing action IAF is applied by the engine ECM CMM under certain conditions.

As shown in the graphs of FIG. 3 and in FIG. 4, when the gear ratio change is initiated at the time t0, an AF lock action is controlled by the vehicle's CTU communication controller and applied by the CMM engine calculator. At the same time, the engine control unit CMM stores in memory the value of the amount of torque taken by the accessories at the moment of initiation of the shift.

If the estimated amount of torque to be taken from the MTH engine accessories A1 to An, at a given moment during the gearshift, is less than the amount of torque taken at the time of the initiation of the change of gear ratio. CdR speeds, then the motor controller CMM sends a signal to the communication controller TCU to request a prohibition of IAF freezing action. The TCU communication controller then commands the engine control unit CMM not to apply the freezing action AF so as to save engine torque to enable the generation of a greater vacuum, and ensure safe braking. This situation is illustrated by the curves 1 and 3 of the second graph of FIG. 3, between the times t0 and ti.

In the same way, when the estimated amount of torque to be taken to the MTH motor by the accessories decreases during the gear ratio change, then the motor controller CMM sends a signal to the communication controller TCU to request a prohibition of IAF freezing action. This situation is illustrated by the curves 1 and 3 of the second graph of FIG. 3, between the times U and t2.

In contrast, when the estimated amount of torque to be taken from the engine (MTH) by the adjustable factor A1 to An increases during the change of gear ratio, the freezing action AF is applied. This situation is illustrated by the curves 1 and 3 of the second graph of FIG. 3, between the times t2 and tf.

It is possible to apply this optimization method according to the invention at any time. Alternatively, it is possible to apply this method only when a critical vacuum threshold, measured by a pressure sensor installed in the amplifier of the "Mastervac" M, is reached.

Thus, the method according to the invention allows both to ensure a certain driving pleasure when changing gears, while ensuring a sufficient generation of vacuum by the engine used by the assistance of the system. braking.

This control method according to the invention is of course compatible with optimization methods of the prior art to obtain a greater depression by the engine to ensure a secure braking (including off the A1 accessories to An consuming torque, and / or increasing the idle speed of the MTH engine, and / or to readjust the position of the camshafts so that there is no more crossover valves).

The configuration as described is not limited to the embodiments described above and shown in the figures. It has been given only as a non-limiting example. Multiple modifications can be made without departing from the scope of the invention. In particular, the vehicle is not limited to two accessories A1, A2. More can be expected, or less if any. One could also provide any type of gearbox BV in the vehicle, manual or automatic. In the case where the gearbox is manual, it is necessary to provide a gear change detection element CdR in the gearbox, able to communicate with the TCU communication controller of the vehicle. One could also imagine that any other computer of the vehicle, able to communicate with the gearbox BV and the various accessories A1 to An and sensors of the vehicle, can implement the method of the invention.

Claims (10)

1. A method for controlling the operation of a heat engine (MTH) of a vehicle, a vacuum in the engine (MTH) being applied to an assistance (M) of the hydraulic braking system of the vehicle, the method applying when a change of gear ratio of the vehicle a freezing action (AF), for driving pleasure, the amount of torque taken from the engine by an adjustable factor (A1, A2 ... An) by adjusting this adjustable factor, characterized in that the method applies a prohibition of the freezing action (IAF) to increase said depression, when the estimated amount of torque to be taken by the adjustable factor (A1, A2 ... An) during the change of ratio of speeds is lower than the amount of torque taken from the engine by said adjustable factor at the moment of initiation of the change of gear ratio, the estimated amount of torque to be taken by said adjustable factor (A1, A2 ... An) being estimated By implementing means of the method of the vehicle. 2. Control method according to claim 1, characterized in that the prohibition of the freezing action (IAF) is applied when the estimated amount of torque to be taken from the motor (MTH) by the adjustable factor (A1, A2. ..An) decreases during gearshift, and the freeze action is applied when the estimated amount of torque to be taken to the engine (MTH) by the adjustable factor (A1, A2 ... An) increases during the shifting gears. 3. Control method according to claim 2, characterized in that the prohibition of the freezing action (IAF) is applied from a detection of a critical vacuum threshold in an amplifier of the assistance (M ) of the braking system. 4. Control method according to any one of claims 1 to 3, characterized in that the freezing action is applied from the initiation of the change gear ratio. 5. Control method according to any one of claims 1 to 4, characterized in that the adjustable factor (A1, A2 ... An) comprises at least one rotating machine applying an adjustable load torque on the engine, as a alternator or air conditioning compressor. 6. Control method according to any one of claims 1 to 5, characterized in that the freezing action (AF) and the estimation of the amount of torque to be taken by the accessories are implemented by a motor ECU (CMM) of the vehicle, able to communicate with the engine (MTH). 7. Control method according to claim 6, characterized in that a communication controller (TCU) of the vehicle, able to communicate with the gearbox (BV) and calculate a moment to initiate a gear ratio change by said gearbox, sends a demand for freezing action (AF) to the engine control unit (CMM) when the gearbox sends a signal relating to the initiation of a shift gear ratio. 8. Control method according to claim 7, characterized in that the prohibition of the freezing action (IAF) is sent by the engine control unit (CMM) to the communication controller (TCU) of the vehicle during a change of gear ratio. 9. Motor vehicle having a heat engine (MTH) producing a vacuum applied to an assistance (M) of the braking system, characterized in that it comprises means for implementing the method of controlling the operation of this engine according to any one of claims 1 to 8. 10. Motor vehicle according to claim 9, characterized in that the gearbox (BV) of the vehicle is a manual gearbox, a gearbox manual driven, an automatic gearbox with hydraulic converter, a gearbox robotized , a continuously variable transmission or a dual clutch transmission.