FR3043047A1 - METHOD FOR OPERATING THE THERMAL MOTOR OF A HYBRID VEHICLE EQUIPPED WITH AIR CONDITIONING - Google Patents

Abstract

A method of optimizing the operation of a heat engine of a hybrid vehicle, driving an electric generator recharging batteries used for traction of the vehicle, the vehicle comprising an air conditioning compressor driven by an electric motor powered by the batteries, the vehicle being stationary or operating in electric mode at a speed below a maximum speed threshold, having a starting method of the engine according to the charge level of the batteries controls this starting with maximum levels of rotation speed (Ω1) and mechanical power output (P), the optimization method realizing in the case where an air conditioning demand is performed, an increase in the maximum levels of rotation speed (Ω2) and mechanical power delivered (P ') .

Description

METHOD FOR OPERATING THE THERMAL MOTOR OF A HYBRID VEHICLE EQUIPPED WITH AIR CONDITIONING

The present invention relates to a method for optimizing the operation of the thermal engine of a hybrid motor vehicle, and a hybrid vehicle comprising means implementing such an optimization method.

A known type of hybrid motor vehicle comprises a heat engine driving the driving wheels by a mechanical transmission, which constitutes the main engine, and an auxiliary electric motor connected to energy storage batteries, which can operate as a motor by delivering a additional torque to the wheels, or generator braking the vehicle to recharge these batteries.

These hybrid vehicles further include an electric generator coupled directly to the engine, which takes mechanical energy to recharge the batteries by its operation.

In addition, in some cases the vehicle has a socket allowing it to be stopped, to recharge the batteries directly on an external power supply network.

These vehicles have different modes of operation, comprising a rolling only with the engine, a fully electric taxi with the auxiliary engine, and a hybrid taxi using both engines.

In the case of a vehicle equipped with an air-conditioning of the passenger compartment, in order to allow operation of this air conditioning with the vehicle stationary or during a taxi in electric mode, the engine being stopped, it It is known to drive the air conditioning fluid compressor by an electric motor that draws energy from the battery. In this way it is possible to obtain an air conditioning of the passenger compartment.

However, in order to reduce the consumption of energy in the batteries by the air conditioning, to preserve the driving autonomy of the vehicle, it is known to limit the power consumed by the air conditioning compressor. This power can be limited to around 1600W.

In particular it is absolutely necessary to avoid emptying the batteries completely, in order to keep available energy allowing in any case to restart the engine after shutdown.

In this case, operation of the air conditioning is obtained in degraded mode, making it possible to maintain a temperature of the passenger compartment under certain conditions, but which may not be sufficient for all use cases, especially if it is necessary to cool the vehicle. cockpit from a high temperature. There is a risk of discomfort that does not fully satisfy the client.

In addition, for hybrid vehicles stopping or running at low speed, in the case where the charge of the batteries is insufficient, it is known to start the engine with a limitation of its speed of rotation and the power delivered. , to avoid vibrations and noise emissions that could be unpleasant for passengers.

The started engine provides a minimum level of charge in the batteries, but the limited energy it delivers generally does not ensure the operation of the air conditioning with high power.

Furthermore, a known thermal engine operating method, presented in particular by the document US-A-6137250, is implemented on a series hybrid vehicle comprising a heat engine driving a generator which recharges by a battery current converter. The batteries as well as the generator supply an electric motor driven driving wheels. This method describes certain starting conditions of the heat engine to recharge the batteries, in particular to limit vibrations and noise emissions.

However, this method does not take into account the demand for operation of an air conditioning to optimize the supply of electrical energy, in order to obtain a satisfactory level of performance of this air conditioning.

The present invention is intended to solve these problems of the prior art.

It proposes for this purpose a process for optimizing the operation of a heat engine of a hybrid vehicle, driving an electric generator recharging batteries used for traction of the vehicle, the vehicle comprising an air conditioning compressor driven by an electric motor powered by the batteries, the vehicle being stopped or running in electric mode at a speed below a maximum speed threshold, having a starting method of the engine which, according to the charge level of the batteries, controls this starting with maximum levels of rotational speed and mechanical power delivered, the optimization method realizing in the case where an air conditioning request is made, an increase in the maximum levels of rotational speed and mechanical power delivered.

An advantage of this optimization method is that the air conditioning is stopped, we obtain the usual operating conditions with if necessary a start of the engine having a rotational speed and a power output corresponding to low levels that give a high comfort.

When the air conditioning requires a lot of energy while the battery charge level is low enough, the process allows a higher rotation speed, a higher torque and a higher output power which represents a compromise between a slightly higher noise level, and a recharge. sufficient batteries delivering stronger power to the air conditioning.

The method of optimizing the operation of the heat engine according to the invention may further comprise one or more of the following characteristics, which may be combined with one another.

In particular, the threshold of maximum driving speed of the electric mode can be between 6 and 10km / h.

Advantageously, the increased maximum levels of rotational speed and mechanical power delivered correspond to an increase in noise emission of the powertrain of between 1 and 2 dBa compared to the operation with the first levels. This increase in sound level is generally covered by the noise of operation of the air conditioning, it does not appear substantially for passengers.

Advantageously, the increased maximum levels of rotation speed and mechanical power delivered, correspond to a noise emission of the powertrain between 71 and 72 dBa.

Advantageously, the increased level of mechanical power delivered is greater than 6000W. This level allows both driving at low vehicle speeds, and an air conditioning power with high power.

In particular, the increased level of mechanical power delivered can be between 7000 and 9000 W. The invention also relates to a hybrid motor vehicle, comprising means implementing a method of optimizing the operation of the engine comprising any of the preceding characteristics. The invention will be better understood and other features and advantages will emerge more clearly on reading the following description given by way of example, with reference to the appended drawings in which: FIG. 1 is a graph showing the proportions different sources of noise depending on the speed of a hybrid vehicle; and - Figure 2 is a block diagram showing the operation of the method according to the invention.

Figure 1 shows the different sources of noise on a hybrid vehicle comprising a heat engine driving an electric generator for recharging the batteries. The energy of these batteries is used by an electric traction motor of the vehicle.

According to the speed of the vehicle V expressed in km / h on the horizontal axis, the percentage of each sound volume B coming from the operation of the powertrain 2 with the engine running, rolling noise 4 wheels on the road, and aerodynamic noises 6.

It can be seen that at standstill there is only the operating noise of the powertrain 2.

When the vehicle starts, up to a speed level VO which is about 25km / h, the share of rolling noise 4 increases linearly to a value of about 55%, the rest of the noise coming from the group powertrain at this time representing approximately 45%. From the speed level VO, there is an appearance and a linear increase in the proportion of the aerodynamic noise. The share of the noise of the powertrain 2 and that of the rolling noise 4 decrease each in a linear manner, this first share being always a little lower than this second part. At the end, at the maximum speed that is in this example of 150 km / h, the share of powertrain 2 noises is about 20%, that of rolling noise 4 is about 30%, the rest is about 50% being the share of aerodynamic noise 6.

It can be seen that for low vehicle speeds, between 6 and 10km / h, especially less than 8km / h, the noise comes almost exclusively from the powertrain, so it is important to manage this sound source in these operating conditions.

FIG. 2 presents the method for optimizing the operation of the heat engine, which is implemented when the vehicle is stationary, or rolls with a low speed in electrical mode below a threshold, which is advantageously about 8 km / h, with a battery charge level that forces the engine to start.

Under these conditions the operation of the air conditioning masks much of the noise of the powertrain.

We then have a first condition 10 on the operation of the air conditioning of the hybrid vehicle. The air conditioning can be put into operation automatically by its regulation system, which measures the interior temperature of the passenger compartment, or at the request of the driver who imposes it by a command.

In the case of "OFF" where the air conditioning is at a standstill, the need for electrical energy only for vehicle advance or battery charging is limited. There is then an operation of the heat engine according to a first condition 12 comprising a low rotation speed of the engine Ω1 and a low power delivered P, which generates a low noise level of the powertrain.

In particular, it is provided by certain manufacturers for a gasoline engine, a low rotation speed of the thermal motor Ω1 of 1050rpm and a mechanical torque taken down of 52Nm, which corresponds to a low mechanical power delivered P of 5750W. Other manufacturers choose a low rotation speed Ω1 of 925rpm and a mechanical torque taken low of 60Nm, which corresponds to a low mechanical power delivered P substantially equivalent to 5800W.

The low mechanical power delivered P is distributed in a mechanical power delivered to the wheel P1 if the vehicle rolls, and a mechanical power delivered to the electric generator P2 to provide a charging current of the batteries.

This results in noise emissions from the powertrain of about 70dBa, which are low.

In the case "ON" where the air conditioning works, it takes electrical energy that adds to the needs for the advance of the vehicle or the recharging of the batteries. The overall need is more important. The operation of the heat engine is then carried out according to a second condition 14 comprising a higher speed of rotation of this motor Ω2 and a higher power output P '.

In particular the higher power delivered P 'can be greater than 6000W, especially greater than 6500W. It is advantageously between 7000 and 9000W, which generally covers the needs of the vehicle in these operating conditions.

In particular, it is possible to choose a higher rotation speed Ω2 of 1100 rpm and a higher mechanical torque of 70 Nm, which corresponds to a high mechanical power delivered P 'of 8060 W.

The high mechanical power delivered P 'is distributed with the same mechanical power delivered to the wheel P1 if the vehicle is moving, and a mechanical power delivered to the electric generator P3 which is larger. We obtain a supplement of electric power which makes it possible to cover practically all the needs of the air conditioning.

In this case the noise level of the powertrain is slightly higher, but it is covered by the operating noise of the air conditioning. In practice it is possible to obtain with the values presented above, an increase of this noise level between 1 and 2dBa, in particular of + 1.5dBa, bringing it to a total of 71.5dBa.

In all cases we obtain an improvement of the air conditioning comfort of the vehicle, with an acoustic performance that is very substantially maintained.

The method according to the invention can be applied in particular for hybrid vehicles having a battery charging socket on an external electricity distribution network.

Claims (7)

1 - Process for optimizing the operation of a heat engine of a hybrid vehicle, driving an electric generator recharging batteries used for traction of the vehicle, this vehicle comprising an air conditioning compressor driven by an electric motor powered by the batteries, the vehicle being stationary or operating in electric mode at a speed below a maximum speed threshold, having a starting method for the engine which, according to the level of charge of the batteries, controls this starting with maximum levels of speed of rotation (Ω1) and of mechanical power output (P), characterized in that in the case where an air-conditioning request is made, it increases the maximum levels of rotation speed (Ω2) and mechanical power output (P ') . 2 - optimization method according to claim 1, characterized in that the threshold of maximum driving speed of the electric mode is between 6 and 10km / h. 3 - Optimization method according to claim 1 or 2, characterized in that the increased maximum levels of rotational speed (Ω2) and mechanical power delivered (P '), correspond to an increase in noise emission of the powertrain included between 1 and 2dBa compared to the operation with the first levels. 4 - Optimization method according to any one of the preceding claims, characterized in that the increased maximum levels of rotational speed (Ω2) and mechanical power delivered (P '), correspond to a noise emission of the powertrain between 71 and 72dBa. 5 - Optimization method according to any one of the preceding claims, characterized in that the increased level of mechanical power delivered (P ') is greater than 6000W. 6 - optimization method according to claim 5, characterized in that the increased level of mechanical power delivered (P ') is between 7000 and 9000W. 7 - Hybrid automobile vehicle, characterized in that it comprises means implementing a method for optimizing the operation of the heat engine according to any one of the preceding claims.