FR2927872A1 - Internal combustion engine starting controlling method for motor vehicle, involves bringing initially stopped engine to rotational speed by action of electric machines during operation phases to permit engine for propulsion of vehicle - Google Patents

Abstract

A method of controlling the starting of an internal combustion engine (1) included in a power-driven hybrid power train for a motor vehicle having at least two driving wheels (5a, 5b), the power train comprising in addition to the engine with internal combustion (1), sensors (12), at least two electric machines (2a, 2b), an electrical storage element (3) and an infinitely variable transmission (4) mechanically connecting the internal combustion engine (1). ), the two electric machines (2a, 2b) and the drive wheels (5a, 5b). During the control process, the internal combustion engine is driven by the electric machines and in several operating phases. (1) initially stopped at a sufficient speed of rotation to participate in the propulsion of the vehicle.

Description

PATENT APPLICATION B07-1549EN Société par Actions Simplifiée known as: RENAULT sas System and method for controlling the starting of the internal combustion engine of a vehicle equipped with an infinitely variable transmission Invention of: GATI Mehdi KEFTI-CHERIF Ahmed MENSLER Michel POGNANT- The field of the present invention is the control of transmissions and more particularly the control of infinitely variable transmissions. Infinitely variable transmissions have found particular momentum with hybrid-powered motor vehicles. Indeed, the infinitely variable transmissions offer the possibility of modulating or increasing the torque delivered by a main power source by varying the pairs delivered by two secondary power sources. In the case of a hybrid-propulsion vehicle, the main driving source is an internal combustion engine, or internal combustion engine, and the secondary drive sources are generally electric machines that can operate as an electric motor or a regenerative braking system. .

When the output shaft connecting an infinitely variable transmission to the drive wheels is blocked, it is possible to transmit a torque of the internal combustion engine to the electric machines and vice versa. In order to reduce the cost of vehicles with hybrid propulsion, it would be interesting to be able to remove the starter, while having a control method for starting an internal combustion engine without using a starter. The present invention relates to a control method for starting a stopped internal combustion engine using only the electric machines. The present invention also relates to a control system for starting a stopped internal combustion engine using only the electrical machines.

According to one aspect of the invention, there is described a method for controlling the starting of an internal combustion engine included in a power-driven hybrid powertrain for a motor vehicle equipped with at least two driving wheels, the powertrain comprising in addition to the internal combustion engine, sensors, at least two electrical machines, an electrical storage element and an infinitely variable transmission mechanically connecting the internal combustion engine, the two electric machines and the drive wheels.

During the control process, the internal combustion engine initially stopped at a speed of rotation sufficient to participate in the propulsion of the vehicle is brought by the action of the electrical machines and in several operating phases.

During a first operating phase defined by a rotational speed of the internal combustion engine lower than a first stored value, the two open-loop electric machines can be controlled with respect to the power supplied by the electrical storage element. so that the rotational speed of the internal combustion engine increases at least up to the first stored value. During a second operating phase defined by a rotational speed of the internal combustion engine between the first stored value and a second stored value, the torque of the two closed loop electric machines can be controlled with respect to an estimate of the rotational speed of the internal combustion engine so that the internal combustion engine reaches a rotational speed greater than the second stored value. The power of the electric storage element supplied to the electrical machines can be determined as a function of the moment of inertia of the internal combustion engine, the rotation speed setpoint of the internal combustion engine and the measurement of the speed of rotation. rotation of the internal combustion engine.

During a third phase of operation defined by a rotational speed of the internal combustion engine greater than the second stored value, the two closed loop electric machines can be controlled with respect to the speed of rotation of the internal combustion engine in order to bringing the torque of the internal combustion engine from a negative value to a stored positive minimum value; then the internal combustion engine and the two electric machines can be controlled so as to control the rotational speed of the internal combustion engine, the torque at the wheel, and the power setpoint that can be delivered by the electric storage element. According to another aspect of the invention, a starting control system of an internal combustion engine included in a power-driven hybrid powertrain for a motor vehicle equipped with at least two driving wheels, the powertrain, is defined. comprising in addition to the internal combustion engine, sensors, at least two electrical machines, an electrical storage element and an infinitely variable transmission mechanically connecting the internal combustion engine, the two electric machines and the drive wheels. The control system comprises means for estimating the rotational speed of the internal combustion engine capable of determining an estimate of the rotational speed of the internal combustion engine as a function of the speeds of rotation of the electrical machines coming from the sensors and a means of for determining the torque setpoints of the electrical machines able to control the electrical machines as a function of a rotational speed reference of the internal combustion engine and of the estimation of the rotational speed of the internal combustion engine.

The control system may comprise: a means for determining the electrical setpoint capable of determining a power setpoint delivered by the electric storage element as a function of a rotational speed reference of the internal combustion engine and of the estimation the rotational speed of the internal combustion engine, an energy control means capable of determining a first control signal as a function of the power setpoint delivered by the electrical storage element and the power measurement delivered by the element electrical storage device from the sensors, a mechanical control means capable of determining a second control signal as a function of the rotational speed reference of the internal combustion engine and of the estimation of the rotational speed of the internal combustion engine, and the means for determining the torque setpoints of the electrical machines being able to translate the first and the uxth control signal in torque setpoints for electrical machines. Other objects, features and advantages of the invention will become apparent on reading the following description, given solely by way of nonlimiting example and with reference to the appended drawings in which: FIG. 1 illustrates a hybrid powertrain; FIG. 2 illustrates the startup control method; and - Figure 3 illustrates the start control system. Figure 1 illustrates an embodiment of a hybrid powertrain with infinitely variable transmission.

An internal combustion engine 1, a first electric machine 2a and a second electric machine 2b are connected to an infinitely variable transmission 4. The output shaft of the infinitely variable transmission 4 is connected to the drive wheels 5a and 5b. A locking system 6 of the output shaft is positioned between the infinitely variable transmission 4 and the drive wheels 5a and 5b. The electrical machines 2a and 2b are connected to an energy storage element 3.

The electrical machines 2a and 2b modulate the torque supplied by the internal combustion engine 1 according to the operating mode of the infinitely variable transmission 4. FIG. 2 illustrates a method for controlling the starting of an internal combustion engine 1. The process command consists essentially of three phases. During a first phase, the internal combustion engine is set in motion by the action of the electric machines. During a second phase, the torque of the electrical machines is modulated so that the rotational speed of the internal combustion engine continues to increase while adjusting the electrical energy supplied by the storage system. Finally, during the third phase, the internal combustion engine is started. I1 thus participates in the engine torque. The control of electrical machines is modified to help the torque of the internal combustion engine. The process begins with step 7 in which it is determined that the driver requests the start of the internal combustion engine 1 while the vehicle is stopped. The detection of the driver's intention can be achieved by determining the depression of the accelerator pedal or the rotation of the starter key. The vehicle is determined to stop especially if its speed is zero and if the output shaft is blocked by a locking system 6, controlled by the driver, decoupled or automated. For example, a parking brake can be engaged, the gearbox can be in a parking position, or a decoupled braking system could block the output shaft. When the preceding conditions are satisfied, the control method continues in step 8. During this step, it is desired to put the internal combustion engine in motion. The output shaft of the powertrain being blocked, all the torque generated by the electric machines 2a and 2b is transferred to the internal combustion engine 1.

On the other hand, the torque of each of the electrical machines depends on the electrical power supplied to it. It is thus possible to directly control the torque provided by the electrical machines by modulating their power supply.

Finally, the infinitely variable transmission that connects the electrical machines and the internal combustion engine involves a relationship between the torques of the electrical machines Tel, Te2 and the resistive torque Ti of the internal combustion engine.

Tel = Al • Ti Te2 = Cl • Ti with Al and Cl kinematic parameters related to the transmission.

It can therefore be concluded that the control of the energy supplied by the electrical storage element makes it possible to control the value of the resistive torque Ti of the internal combustion engine. During step 8, the power supplied by the storage element is increased in order to increase the rotation speed Wice of the internal combustion engine.

When the rotation speed Wice of the internal combustion engine is greater than a first stored value, the process continues with step 9. In this step, it is desired to continue increasing the rotation speed Wice of the internal combustion engine while by limiting the amount of energy consumed. We will therefore go from an open loop control of the electric power supplied by the storage element to a closed loop control. During step 9, the rotation speed Wice of the internal combustion engine is estimated as a function of the Wel and We2 rotation speeds of the electric machines 2a and 2b. The powertrain mechanical architecture implies that Wice results from the combination Linear of Wel and We2. The average mechanical power P (t) necessary to drive the internal combustion engine from its current speed of rotation Wice to the target rotation speed Wice ref in a given time T is then determined. P (t) = I. J. (Wice ref (t ~ - Wice2 (t)) (Eq 1) with J = the moment of inertia of the internal combustion engine.

The average mechanical power is then converted into Pbat_ref power setpoint taking into account the mechanical / electrical conversion efficiency. Pbat ref (t) = P (t) • k where k is a setting parameter less than unity.

The electrical machines are slaved according to the power setpoint Pbat_ref and the measured power Pbat_mes. In fact, in general, the mechanical power produced by the electrical machines is proportional to the power supplied by the electrical storage element. The ratio between the two powers being related to the mechanical / electrical conversion efficiency, noted previously, and to the electrical losses. Thus, the servocontrol is performed by posing that the power to be supplied by the electrical machines is modulated so that the energy consumed tends towards the power setpoint Pbat_ref. The internal combustion engine 1 is also slaved according to the rotation speed setpoint Wice_ref and according to the estimated rotational speed Wice. As the motor is rotated by the action of the electric machines, the slaving of the rotational speed of the internal combustion engine amounts to slaving the speeds of rotation of the electrical machines to the speed reference of the internal combustion engine Wice. ref. When the rotational speed of the internal combustion engine Wice reaches a second stored value, representing the rotational speed threshold to be reached at the end of step 9, the method continues in step 10.

In step 10, the internal combustion engine 1 has a rotational speed sufficient for fuel injection to begin. As a result, a motor torque can be generated. However, there is a period during which the torque generated by the internal combustion engine changes from a torque resistant to a motor torque. During this period, it is possible that jolts will be felt if the combustion engine is not assisted by the electric machines. To avoid such inconvenience of driving, the control of the electrical machines described in step 9 is maintained. This control is coupled to an increase in open loop torque Tice of the internal combustion engine as it describes an increasing ramp, starting from a negative value (resistive torque) and increasing to a positive value (motor torque). Preferably, the growth is linear. As soon as the torque of the internal combustion engine reaches a stored setpoint, step 10 ends. The process in turn terminates with step 11 in which the internal combustion engine is considered started, rotating, and providing a driving torque. In Figure 2 is illustrated a control system 30 of the start. The control system 30 comprises means 13 for estimating the rotational speed of the internal combustion engine, means 14 for determining the electrical power setpoint, energy control means, mechanical control means, means for controlling the electric motor. determination system 17 of the torque setpoints, and a memory 23. The control system 30 is connected at the input to the sensors 12 and at the output to the electrical machines 2a and 2b. The means 13 for estimating the rotational speed of the internal combustion engine is connected via its inputs to the sensors 12 via the connections 20 and 21, and at the output to the means 14 for determining the electrical power setpoint via the connection 22. The means 14 for determining the electrical power setpoint is furthermore inputted to a memory 23 via the connection 24 and at the output to the energy control means 15 via the connection 25 and to the mechanical control means 16 via the bypass 31 of the its 29 output connection. The energy control means 15 is furthermore connected to the sensors 12 via the connection 26.

The mechanical control means 16 is connected at input by means of estimation 13 of the speed of rotation of the internal combustion engine by a bypass 27 of the connection 22, and to the memory 23 by a bypass 28 of the connection 24. The means 17 for determining the torque setpoints is inputly connected to the energy control means 15 via the connection 29 and to the mechanical control means 16 via the connection 28. The determination means 17 is also connected to the sensors 12 via the input. bypass 32 of the connection 21 and by the bypass 33 of the connection 20. The determination means 17 of the torque setpoints is connected at the output by the connection 18 to the first electrical machine 2a and by the connection 19 to the second electrical machine 2b . The sensors 12 determine the rotation speeds Wel and We2. The means 13 for estimating the speed of rotation of the internal combustion engine determines the rotation speed Wice of the internal combustion engine as a function of the rotation speeds Wel and We2 of the first electric machine 2a and the second electric machine 2b. The determination means 14 of the electrical power setpoint determines an electric power setpoint Pbat_ref as a function of the rotation speed Wice of the internal combustion engine and a rotation speed reference Wice_ref of the internal combustion engine. The determination means 14 of the power setpoint compares the rotation speed of the internal combustion engine Wice with a set value present in the memory 23 in order to determine the phase corresponding to the current situation. The memory 23 comprises in particular a first stored value and a second stored value. The first stored value corresponds to the reference value of the rotational speed of the internal combustion engine marking the transition between the first and the second phase. The second stored value corresponds to the reference value of the rotational speed of the internal combustion engine marking the transition between the second and the third phase. If the means 14 for determining the power setpoint determines that the internal combustion engine is in the first phase, it emits an electric power setpoint Pbat_ref corresponding to an internal mapping. The internal mapping includes the allowed values of electrical power Pbat_ref. The electric power setpoint Pbat_ref is increased until the internal combustion engine is in the second phase of operation. If the internal combustion engine is detected as being in the second or third phase, the electric power setpoint Pbat_ref is determined by calculation and not by mapping. The calculation begins with the estimation of the mechanical power necessary to increase the speed of rotation of the internal combustion engine, from the current value Wice to the setpoint value Wice ref in a given duration T. This duration T may for example be a fraction of the duration of operation deemed acceptable by the driver. Equation 1 makes it possible to determine the mechanical power P (t) to be deployed in order to bring a mechanical inertia motor J from a rotation speed Wice to a speed of rotation Wice ref in a duration T. The mechanical power P (t ) multiplied by the mechanical / electrical efficiency of the electrical machines to obtain the electric power setpoint Pbat_ref. This electric power setpoint Pbat_ref and the electric power Pbat measured by the sensors 12 are used by the energy control means 15 to determine a control parameter uw of the electrical machines. At the same time, the mechanical control means 16 determines a control parameter uo of the electrical machines as a function of the rotational speed Wice of the internal combustion engine and the rotation speed reference Wice_ref of the internal combustion engine. uo = kp • (Wice ref ù Wice) + k; • J (Wice ref ù Wice) + kd (Wice_ref ù Wice A derivative integral proportional type determination can be used to determine the control parameter uw by minimizing the difference between the rotational speed Wice of the internal combustion engine and the the speed reference Wice_ref of the internal combustion engine.

The means 17 for determining the torque setpoints input the control parameters uw and uo and the Wel measurement of the rotational speed of the first electrical machine and the measurement We2 of the rotational speed of the second electrical machine. The torque setpoint Tel of the first electric machine 2a and the

Torque reference Te2 of the second electrical machine 2b are determined according to the following system of equations: ~ uw (ùWei ùWe2 (Tel

uo Kl (Wel, We2) K2 (Wel, We2) Te2i with Kl (Wel, We2) and K2 (Wel, We2) two functions of

rotational speeds of the electrical machines chosen such that the matrix ù Wel ùWe2 is invertible. Kl (Wel, We2) K2 (Wel, We2) It should be noted that during the third phase, the instructions for

couple Tel and Te2 are maintained the time that the torque Tice of the

internal combustion engine goes from a negative value to a value

positive. The value Tice is determined independently from values received from the sensors. In particular, a positive value Tice_inj is determined, from which the injection can be performed. The value Tice_inj can be determined by performing a power budget. As a first approximation, we can estimate Tice_inj as follows: Pbat ref Ticeinj = 30 Wice When the value Tice_inj is reached, the power transmitted by the electric motor balances the power setpoint Pbat_ref. Thus, a relay smoothly is realized during the ignition of the engine.

The control system and the control method make it possible to start a stopped internal combustion engine by using the mechanical power generated by electrical machines through infinitely variable transmission. The starting is carried out by means of phases making it possible to progressively raise the speed of rotation of the internal combustion engine.

Claims (7)

1. A method for controlling the starting of an internal combustion engine (1) included in a power-driven hybrid powertrain for a motor vehicle equipped with at least two driving wheels (5a, 5b), the powertrain further comprising the internal combustion engine (1), sensors (12), at least two electric machines (2a, 2b), an electrical storage element (3) and an infinitely variable transmission (4) mechanically connecting the internal combustion engine (1), the two electric machines (2a, 2b) and the driving wheels (5a, 5b), characterized in that the electric motor is brought into operation by means of electrical machines and in several operating phases. internal combustion (1) initially stopped at a sufficient rotation speed in order to participate in the propulsion of the vehicle. 2. A control method according to claim 1, wherein during a first operating phase defined by a rotational speed of the internal combustion engine less than a first stored value, the two electrical machines (2a, 2b) are controlled by open loop with respect to the power provided by the electric storage element (3) so that the rotational speed of the internal combustion engine (1) increases at least up to the first stored value. 3. A control method according to claim 2 wherein during a second phase of operation defined by a rotation speed of the internal combustion engine between the first stored value and a second stored value, the torque of the two machines is controlled electric motors (2a, 2b) in a closed loop with respect to an estimation of the rotational speed of the internal combustion engine (1) so that the internal combustion engine (1) reaches a rotational speed greater than the second stored value. 4. Control method according to claim 3 wherein the power of the electric storage element (3) supplied to the electrical machines (2a, 2b) is determined as a function of the moment of inertia of the internal combustion engine, the rotational speed reference of the internal combustion engine and measurement of the rotational speed of the internal combustion engine. 5. Control method according to one of claims 3 or 4, wherein during a third operating phase defined by a rotational speed of the internal combustion engine greater than the second stored value, the two electrical machines are controlled (2a, 2b) closed loop with respect to the rotational speed of the internal combustion engine (1) to bring the torque of the internal combustion engine from a negative value to a stored positive minimum value; then the internal combustion engine and the two electric machines (2a, 2b) are controlled so as to control the rotation speed of the internal combustion engine, the torque at the wheel, and the power setpoint that can be delivered by the storage element electric. 6. Control system for starting an internal combustion engine (1) included in a hybrid powertrain with power bypass for a motor vehicle equipped with at least two driving wheels (5a, 5b), the powertrain further comprising the internal combustion engine (1), sensors (12), at least two electric machines (2a, 2b), an electrical storage element (3) and an infinitely variable transmission (4) mechanically connecting the internal combustion engine (1), the two electric machines (2a, 2b) and the drive wheels (5a, 5b), characterized in that it comprises a means (13) for estimating the rotational speed of the suitable internal combustion engine determining an estimate of the rotational speed of the internal combustion engine as a function of the rotational speeds of the electrical machines from the sensors (12); and a means (17) for determining the torque values of the electric machines (2a, 2b) adapted to control the electrical machines (2a, 2b) as a function of a rotational speed reference of the internal combustion engine (1) and of the estimation of the rotational speed of the internal combustion engine (1). 7. Control system according to claim 6, comprising a means (14) for determining the electrical power setpoint capable of determining a power setpoint delivered by the electric storage element (3) as a function of a speed reference. of rotation of the internal combustion engine (1) and of the estimation of the rotational speed of the internal combustion engine (1), an energy control means (15) able to determine a first control signal according to the setpoint power delivered by the electrical storage element (3) and the power measurement delivered by the electrical storage element (3) from the sensors (12), a mechanical control means (16) able to determine a second control signal according to the rotational speed reference of the internal combustion engine (1) and the estimation of the rotation speed of the internal combustion engine (1), the means (17) for determining the logs couple of electric machines (2a, 2b) being able to translate the first and the second control signal into torque setpoints for the electrical machines (2a, 2b).