FR2965667A1 - BATTERY COOLING SYSTEM FOR AN ELECTRIC OR HYBRID VEHICLE - Google Patents

Abstract

Battery cooling installation for an electric or hybrid vehicle (24) parked at a parking space (22), using a cooling air flow which exchanges heat with these batteries by means of an exchanger, characterized in that it comprises an air circuit comprising at least one duct (4) for cooling air taken from the ambient medium, which is buried in the ground (2) to a certain depth, and an outlet mouth (14) air flow comprising connection means on the vehicle (24) for conducting this flow to the heat exchanger of the batteries.

Description

BATTERY COOLING SYSTEM FOR AN ELECTRIC OR HYBRID VEHICLE

The present invention relates to a battery cooling system for an electric or hybrid vehicle, and an electric or hybrid vehicle adapted for such an installation. Electric vehicles, or hybrids using electrical energy, comprise energy storage means such as electrochemical accumulators or capacitors of high capacity, hereinafter called batteries, comprising series of elements that can be recharged by accumulating. an electrical energy, and restore it by feeding an electric traction machine. The energy storage capacity of the batteries is an important characteristic which determines in particular the autonomy of the vehicle in the case of an electric vehicle, or the fuel consumption and the emissions of gaseous pollutants in the case of a hybrid vehicle. The various types of battery commonly used, such as electrochemical batteries Li-ion type, Ni-MH or NI-Zn, have characteristics that degrade as a function of their temperature rise. In particular for use or storage at temperatures above a threshold of about 40 ° C, it can be seen faster aging including in particular a decrease in storage capacity, and an increase in internal resistance and impedance, this aging accelerating according to the temperature level reached and the duration of exposure to this temperature. It can be seen in particular for a stationary vehicle which is exposed to strong solar radiation, an internal temperature of the vehicle and also batteries, which can rise significantly above 40 ° C, and in some cases exceed 70 ° C . The characteristics of the batteries are deteriorating, and the cost of the mileage traveled by this vehicle increases especially as these batteries always have a high cost.

Moreover, if the vehicle is stopped with its batteries being charged on a charging station, the passage of the current and the electrochemical reactions due to this recharge generate calories that heat up these batteries, the problem of cooling is all the more important. A known solution for cooling the batteries on a stationary vehicle is to use the air conditioning of this vehicle, which is a problem because the air conditioning devices consuming a significant amount of energy, the overall energy balance is degraded.

Another known cooling system for batteries of a vehicle, presented in particular in the document FR-A1-2941568, comprises an outside air intake disposed under the vehicle substantially in the center of the latter, so as to collect water. air in the shade which is relatively cooler when the vehicle is exposed to the sun, to come cool these batteries. This system can improve the cooling of the batteries, but even in the shade the air taken can have a relatively high temperature, so that the cooling capacity, which is proportional to the square of the temperature difference, remains low.

The present invention is intended to avoid these disadvantages of the prior art, and to provide a battery cooling system for a vehicle at a standstill, which is simple, effective and economical. It proposes for this purpose a battery cooling system for an electric or hybrid vehicle parked at a parking space, using a cooling air flow which performs a heat exchange with these batteries by means of an exchanger, characterized in that it comprises an air circuit comprising at least one air cooling duct taken from the ambient medium, which is buried in the ground to a certain depth, and an air outlet outlet comprising a means of connection to the vehicle, to drive this flow to the battery heat exchanger. An advantage of this cooling installation is that the cooling pipe buried at a certain depth makes it possible to benefit from a soil with a substantially constant temperature remaining at approximately 12 ° C., which cools the air carried in these pipes, this ground constituting a cold source that is always available and does not consume energy. The cooling installation according to the invention may further comprise one or more of the following features, which may be combined with each other. Advantageously, the buried pipe is at least about 1.20m from the level of this ground. Advantageously, the cooling air circuit comprises a ventilation means circulating the air in this circuit. Advantageously, the ventilation means is started at the request of a battery monitoring system installed on the vehicles. In particular, the cooling installation may not include means of ventilation of the air circuit, and use a ventilation means specific to the vehicle to circulate the air in this circuit. According to one embodiment, the cooling installation comprises a single buried pipe leading air to a distribution terminal, which distributes the flow of air to several outlet mouths each capable of supplying a vehicle. According to another embodiment, the cooling installation comprises several buried pipes, having a common inlet or particular entries, each buried pipe leading a flow of air to an outlet mouth can supply a vehicle.

In particular, the means for connecting the outlet mouth can use a telescopic pipe which slides vertically, to connect the outlet of the cooling air circuit to an air inlet located below the vehicle.

The outlet mouth can be arranged concentrically with a primary induction coil, which transmits electrical energy to the vehicle in the case of induction charging. The invention also relates to an electric or hybrid vehicle, using a cooling air flow to achieve a heat exchange with its batteries by means of an exchanger, and having an inlet of this air flow comprising a connecting means with an outlet mouth of a cooling installation having any of the preceding features. The invention will be better understood and other features and advantages will appear more clearly on reading the following description given by way of example, with reference to the accompanying drawings in which: - Figure 1 is a sectional view of a buried circuit for circulating air, used by a cooling installation according to the invention; - Figure 2 is a diagram showing a top view, a parking comprising a cooling system according to the invention; and FIGS. 3 and 4 are diagrams of the car park comprising cooling installations made according to variants. FIG. 1 shows the earth floor 2 seen in section, in which is buried a substantially horizontal pipe 4, having at one end a vertical portion 6 rising to the surface, which terminates in an air intake forming a protected inlet 8 bad weather by a hat. The other end of the buried pipe 4 also terminates in a vertical part 10, comprising on the surface an air extraction fan 12 which directs the air coming from the inlet 8, towards an outlet mouth 14.

The buried pipe 4 has a small slope, ending in the lower part by a trap 16 for discharging condensation water that may form on the walls of this pipe. It is found that the earth from a depth of about 1.20m, has a temperature of about 12 ° C which becomes almost constant throughout the year. The circulation of hot air from the inlet 8 and forced by the air extraction fan 12 into the pipe 4 buried at this depth, causes the walls to contact a cooling air. By adjusting the parameters of length and diameter of the buried pipe 4 which serves as a heat exchanger, and air flow velocity, one can obtain a substantial refresh. The outside air entering, for example, at a temperature of 30 ° C., can be discharged at a temperature of between 15 and 20 ° C., the mass of the earth constituting a high thermal capacity permitting continuous operation of this cooling installation. Thus, economically and ecologically, with a very low energy input of essentially to the supply of the air extraction fan 12, a simple, economical and efficient cooling means, which is also called the Provençal well, is produced.

Figure 2 shows a parking 20 with four parking spaces 22, each receiving a vehicle 26 which is hybrid or electric. Each parking space 22 has a cooled air outlet 14, which is substantially in the center of the place so as to come in the middle of the vehicle 26 parked thereon.

The air inlet 8 constitutes the inlet of a single buried pipe 4, which opens into a distribution terminal 30 distributing the cooled air in four flexible supply pipes 28 each having an outlet mouth 14, the flexibility these pipes allowing the driver to come and connect it tightly on his vehicle 24.

Each supply pipe 28 comprises an air extraction fan 12, to force the passage of air through the buried pipe 4 and to obtain at the outlet mouths 14 a sufficient air flow. The vehicle 24 is parked in its parking space 22 having in the central position, a primary charging coil 26 which is laid flat on the surface of the ground. The vehicle 24 comprises at its floor a secondary coil also laid flat, which is superimposed on the primary coil 26, to inductively transmit electrical energy from the primary coil to the secondary.

The energy received by the secondary coil serves after shaping the current, to recharge the batteries of the hybrid or electric vehicle 24. The vehicle 24 has under the floor an air inlet which is fitted above the outlet mouth 14, the fresh air coming out of this mouth being led to a heat exchanger cooling the batteries by a warming of the air, which is then rejected to the outside. The watertight connection system may be an automated system that connects when the vehicle 24 comes into position on its parking space 22. To facilitate the connection between the outlet port 14 and the air inlet of the vehicle 24, the pipe supply 28 may be rigid, and include an outlet mouth comprising a telescopic pipe that rises when the vehicle is in place, to come into contact with a suitable portion of its air inlet and ensure a tightness of the connection. On the contrary, it is also possible to arrange a telescopic pipe on the vehicle 24, which descends to come into contact with the outlet mouth 14 which is on the ground. Advantageously, the exhaust air fan 12 is started at the request of the battery monitoring system installed on the vehicle 24, so as not to unnecessarily distribute fresh air. The vehicle then comprises a connection for exchanging information with the control of the ventilation means 12.

The exhaust fan 12 can also be included in the vehicle 24, and directly driven by this vehicle on demand, which simplifies the realization of the ground cooling system which is then fully passive.

Alternatively, one could use a complementary circuit of a heat transfer liquid between the distribution terminal 30 and the vehicle 24, which connects sealingly with the heat exchanger of the vehicle, the liquid being heated at the vehicle batteries, and cooling with refreshing air at the dispensing terminal.

FIG. 3 shows a first variant of the cooling installation for the parking lot 20, comprising a single air inlet 8 which simultaneously feeds four independent underground pipes 4. Each buried pipe 4 comprises its air extraction fan 12, and is extended by a supply pipe 28 to supply each of the outlet mouths 14 of the parking area 20. An air circulation regime is thus obtained in the pipes buried 4 which is different, with reduced pipe flow compared to the previous case. FIG. 4 shows a second variant of the cooling installation for the car park 20, comprising four distinct air inlets 8 which each independently feed a buried pipe 4. It is thus possible to use small air inlets 8 , which have a lower airflow than in the previous case. In this figure, the ground primary coils 50 of the parking spaces 22 each surround an outlet mouth 14 which is in the center, to form a concentric compact assembly. In the same way under the vehicle 24, the secondary coil surrounds the air inlet of the heat exchanger to maintain an alignment of these elements with those arranged on the ground, and to achieve a compact assembly. In general, the cooling of the batteries is advantageously implemented during the recharging of these batteries, in particular during fast recharges which are more exothermic, to compensate for the heating from this charge. It is thus possible to cool for long periods the batteries of vehicles parked in parking lot 20, for example during a full day of exposure to the sun which can heat parts of the vehicle to more than 70 ° C., with a very high energy consumption. low that is unrelated to the significant thermal energy transfer achieved at the batteries. The aging of the battery, which is accelerated by exposure to high temperatures, is thus economically limited.

In addition, the batteries are kept permanently cooled, there is a vehicle benefiting from the start of good performance that could not be delivered by batteries at a higher temperature.

Claims (10)

CLAIMS1 - Battery cooling installation for an electric or hybrid vehicle (24) parked at a parking space (22), using a cooling air flow which performs a heat exchange with these batteries by means of an exchanger, characterized in that it comprises an air circuit comprising at least one air cooling pipe (4) taken from the ambient medium, which is buried in the ground (2) at a certain depth, and an outlet mouth ( 14) of the air flow comprising connecting means on the vehicle (24), to conduct this flow to the heat exchanger of the batteries. 2 - battery cooling system according to claim 1, characterized in that the buried pipe is at least about 1.20m from the level of the ground. 3 - battery cooling system according to claim 1 or 2, characterized in that the cooling air circuit comprises a ventilation means (12) circulating the air in this circuit. 4 - battery cooling system according to claim 3, characterized in that the ventilation means (12) is started at the request of the battery monitoring system installed on the vehicles (24). 5 - battery cooling system according to claim 1 or 2, characterized in that it does not include ventilation means, and uses a vehicle-specific ventilation means (24) for circulating the air in this circuit. 6 - battery cooling installation according to any one of the preceding claims, characterized in that it comprises a single buried pipe (4) leading the air to a distribution terminal (30), which distributes the air flow to several outlets (14) each capable of supplying a vehicle (24). 7 - battery cooling installation according to any one of claims 1 to 5, characterized in that it comprises a plurality of buried pipes (4), having a common inlet or particular inputs (8), each buried pipe driving a flow of air to an outlet mouth (14) that can feed a vehicle (24). 8 - battery cooling installation according to any one of the preceding claims, characterized in that the means of connection of the outlet mouth (14) uses a telescopic pipe which slides vertically, to connect the outlet of the air circuit of cooling to an air inlet located below the vehicle (24). 9 - battery cooling installation according to any one of the preceding claims, characterized in that the outlet mouth (14) is arranged concentrically with a primary induction coil (50) which transmits electrical energy to the vehicle (24) in the case of induction charging. 10 - Electric or hybrid vehicle (24), using a cooling air flow to achieve a heat exchange with its batteries by means of an exchanger, characterized in that it comprises an inlet of this air flow comprising a connection means with an outlet mouth (14) of a cooling installation according to any one of the preceding claims.