Mild hybrid vehicle comprising a low-temperature cooling circuit

Abstract

One aspect of the invention relates to a mild hybrid vehicle (1) comprising a low-temperature cooling circuit (2) that extends through a heat exchanger (3), further comprising an inverter (4), a first pipe (8) of a power battery (5), a DC-to-DC converter (15), and a pump (16), said vehicle (1) being characterized in that: the low-temperature cooling circuit (2) comprises a second pipe (20) that is connected to the output of the inverter (4) and to the inlet of the heat exchanger (3), said second pipe (20) being opposite a radiator (19) for cooling a heat engine (17), the radiator (19) being arranged in an accessory facade (21) of the vehicle (1), and in that the low-temperature cooling circuit (2) contains a volume of cooling liquid defined to limit an increase in the temperature of the cooling liquid to +5°C during an electric driving phase lasting 55 to 65 seconds.

Description

DESCRIPTION TITLE OF THE INVENTION: SEMI-HYBRID VEHICLE FEATURING A LOW-TEMPERATURE COOLING CIRCUIT

[0001] The present invention claims priority from French application No. 2212900 filed on 07.12.2022, the content of which (text, drawings and claims) is incorporated herein by reference.

[0002] One aspect of the invention relates to a semi-hybrid vehicle comprising a low-temperature cooling circuit, in particular of a power battery and an inverter of an electric traction machine.

[0003] Such a semi-hybrid vehicle is better known by the acronym MHEV (for "Mild Hybrid Electric Vehicle" in English) and may include a power battery with a voltage of 48V.

[0004] Generally speaking, there are different operating modes for a semi-hybrid vehicle, namely: An electric mode, also sometimes called "ZEV" (an acronym in English for "Zero Emission Vehicle"), in which the vehicle is propelled and / or pulled by the electric traction machine without the intervention of a thermal engine; A thermal mode in which the vehicle is towed and / or propelled solely by the internal combustion engine without the intervention of the electric traction machine; and A hybrid mode in which the vehicle is towed and / or propelled simultaneously by means of the internal combustion engine and the electric traction machine.

[0005] During operation, the power battery associated with the electric traction machine must not exceed its maximum operating temperature. To cool the power battery, it is known in the prior art to equip the vehicle with a low-temperature cooling circuit. When the vehicle is operating in electric mode, the circuit of Low-temperature cooling according to the prior art is the only cooling circuit used to cool the power battery. If the demands placed on the traction electric machine and the inverter are significant, the temperature of the coolant in the low-temperature cooling circuit rises rapidly until it approaches or reaches a maximum operating temperature.

[0006] As described in document FR-A1-3061110, one solution for lowering the coolant temperature in the low-temperature cooling circuit is to install a radiator and a thermostat upstream of the radiator to control the coolant flow through it. This radiator and thermostat aim to limit the temperature rise of the coolant circulating in the low-temperature cooling circuit.

[0007] However, the available space at the front of a mild hybrid vehicle for installing the low-temperature cooling system's radiator is often limited. Installation constraints are further compounded in a mild hybrid vehicle with the presence of, in addition to the internal combustion engine, the electric traction motor, power components, and the power battery. Such a solution is therefore unsatisfactory due to both space constraints and cost.

[0008] The aim of the invention is in particular to offer a semi-hybrid type vehicle comprising a low temperature cooling circuit with a reduced footprint.

[0009] In this context, the invention, in its broadest sense, relates to a semi-hybrid vehicle comprising a low-temperature cooling circuit passing through a heat exchanger arranged to cool a cooling fluid in the low-temperature cooling circuit, an inverter for an electric traction machine of the semi-hybrid vehicle, a first conduit for a power battery arranged to supply energy to the electric traction machine, and a DC-DC converter arranged to recharge a service battery of said semi-hybrid vehicle by means of the battery. power, and a pump arranged to force circulation of the cooling fluid in the low-temperature cooling circuit.

[0010] The semi-hybrid vehicle according to this aspect of the invention is remarkable in that the low-temperature cooling circuit includes a second pipe connected at the output of the inverter and at the input of the heat exchanger, the second pipe being opposite a cooling radiator of a thermal engine arranged in an accessory front of the semi-hybrid vehicle and in that the low-temperature cooling circuit contains a volume of coolant defined to limit a temperature increase of the coolant to +5°C during an electric driving phase of between 55 and 65 seconds.

[0011] The inverter significantly increases the coolant temperature when the vehicle is in electric driving mode. Therefore, the second pipe, positioned opposite the internal combustion engine's radiator, effectively cools the coolant circulating in the second pipe, and particularly the coolant exiting the inverter.

[0012] Furthermore, the coolant volume, designed to limit the coolant temperature increase to +5°C during an electric driving phase lasting between 55 and 65 seconds, facilitates coolant cooling without the need for a radiator in the low-temperature cooling circuit. Thus, the radiator and thermostat typically found in the prior art low-temperature cooling circuit are eliminated thanks to this specific arrangement.

[0013] The size and cost of the low-temperature cooling circuit according to this aspect of the invention are further reduced.

[0014] In addition to the characteristics mentioned in the preceding paragraph, the vehicle according to the invention may have one or more additional characteristics from among the following, considered individually or according to all technically possible combinations.

[0015] According to a non-limiting aspect of the invention, the coolant has a volume between 1.7 liters and 1.9 liters.

[0016] According to a non-limiting aspect of the invention, the coolant is composed of 45% to 55% water and 45% to 55% glycol.

[0017] According to a non-limiting aspect of the invention, the pump is arranged to generate, An initial flow occurs when the temperature of the power battery or the coolant is below a threshold temperature; and A second flow rate higher than the first flow rate when the temperature of said power battery or said coolant is higher than said threshold temperature.

[0018] According to a non-limiting aspect of the invention, the power battery has a thermal resistance of less than 0.05 K / W.

[0019] According to a non-limiting aspect of the invention, the power battery has a chemistry comprising a cobalt content of between 30 and 35%.

[0020] According to a non-limiting aspect of the invention, the power battery comprises a casing equipped with a wall in which a first conduit is provided.

[0021] According to a non-limiting aspect of the invention, the housing contains cells, each cell comprising an electrolyte totally filling said cell.

[0022] According to a non-limiting aspect of the invention, each cell comprises cell walls whose thickness is between 1.8 mm and 2.2 mm.

[0023] According to a non-limiting aspect of the invention, each cell comprises an electrical insulator disposed between a winding of said cell and the cell walls, said electrical insulator being formed by a polyimide.

[0024] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures.

[0025] [Fig. 1] illustrates, schematically, a non-limiting example of an embodiment of a semi-hybrid type vehicle according to the invention.

[0026] [Fig. 2] illustrates, schematically, a non-limiting example of an embodiment of a power battery equipping a semi-hybrid type vehicle according to the invention.

[0027] [Fig. 3] schematically illustrates a wall of a casing of the power battery shown in figure 2.

[0028] [Fig. 4] schematically illustrates a cell of the power battery shown in figure 2.

[0029] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0030] In particular, Figure 1 illustrates a semi-hybrid vehicle 1 equipped with a low-temperature cooling circuit 2 in which a cooling fluid circulates. This cooling fluid is formed by a heat transfer fluid.

[0031] A semi-hybrid vehicle is defined as a hybrid vehicle with a "small" electric traction machine powered, for example, by 48V or 24V.

[0032] The semi-hybrid vehicle 1 illustrated in Figure 1 further includes a heat exchanger 3 arranged to cool the coolant fluid of the low-temperature cooling circuit 2; this heat exchanger 3 is also known by the English term Chiller.

[0033] Furthermore, the heat exchanger 3 is arranged to cool the coolant of a high-temperature cooling circuit (not shown) which comprises the semi-hybrid vehicle 1. The high-temperature cooling circuit is used, in particular, to cool the temperature of the internal combustion engine of the semi-hybrid vehicle 1.

[0034] The semi-hybrid vehicle 1 also includes an inverter 4 of an electric traction machine (not shown) of the semi-hybrid vehicle 1.

[0035] In a non-limiting example of embodiment, when the temperature of inverter 4 is between 35°C and 40°C and it is subjected to electric rolling for 60 seconds, inverter 4 is arranged to generate a loss of the order of 150W.

[0036] To improve the cooling of the cooling fluid, inverter 4 can be thermally isolated from the traction electric machine. To this end, Inverter 4 may include a plastic casing providing thermal insulation from the electric traction machine.

[0037] The semi-hybrid vehicle 1 also includes a power battery 5 arranged to supply energy to the electric traction machine. The power battery 5 may, for example, be of type 48V or 24V.

[0038] In a non-limiting embodiment, the power battery 5 has a thermal resistance of less than 0.05 kW, for example 0.04 K / W. This low thermal resistance makes it possible to limit the temperature difference to 5°C between the power battery 5 and the coolant contained in the low-temperature cooling circuit 2.

[0039] In an example of an embodiment illustrated in Figure 2, in order to obtain this low thermal resistance of 0.04 kW, the power battery 5 includes a casing 6 containing cells 7. A first channel 8 for the passage of the coolant is provided directly in the walls 9 of said casing 6. Thus, the coolant circulates as close as possible to the cells 7 to be cooled. The casing 6 can be made of aluminum.

[0040] Figure 3 illustrates such a casing wall 9. The first conduit 8 is formed in this non-limiting embodiment by two U-shaped channels.

[0041] Furthermore, as illustrated in Figure 4 showing a cell 7 of the power battery 5, a thermal paste 10 is disposed between the walls 11 of the cell 7 and the casing 6 of the power battery 5. This thermal paste 10 can also be disposed between the bottom of the casing 6 and the bottom of the cell 7. This thermal paste 10 facilitates heat conduction between the cells 7 and the casing 6.

[0042] In a non-limiting implementation, each cell wall 11 has a thickness between 1.8 mm and 2.2 mm, typically 2 mm. This significant thickness allows heat to drain from the long sides of the cell 7 to the casing walls 9.

[0043] Each cell 7 of the power battery 5 includes an electrical insulator 12 arranged between a winding 13 of the cell 7 and its walls 11. This winding 13 is more commonly known by the Anglo-Saxon term "Jelly-roll". In a non-limiting embodiment, the electrical insulator 12 is formed by a polyimide. The polyimide is an excellent conductor of heat and it allows to obtain an electrical insulator 12 with a thin thickness.

[0044] In addition, each cell 7 is filled with an electrolyte 14. The electrolyte 14 reaches a maximum level in the cell 7. In other words, the electrolyte 14 is at the very top of the cell 7. This high level allows the maximum conduction of heat from the winding 13 to the cell walls 11.

[0045] In a non-limiting embodiment, the power battery 5 has a chemistry with a cobalt content between 30 and 35%, typically 33%. Compared to prior art power batteries, the chemistry used in the invention has a high cobalt content, allowing the power battery 5 to be used at a temperature of around 45°C without damage.

[0046] The semi-hybrid vehicle 1 also includes a DC-DC converter 15 (or DC / DC converter) arranged to recharge a service battery (not shown) of the semi-hybrid vehicle 1 by means of the power battery 5.

[0047] In a non-limiting example of embodiment, when the temperature of the DC-DC converter 15 is between 35°C and 40°C and it is subjected to electric rolling for 60 seconds, the DC-DC converter 15 is arranged to generate a loss of the order of 80W.

[0048] The semi-hybrid vehicle 1 further includes a pump 16 arranged to force circulation of the coolant in the low-temperature cooling circuit 2. The pump 16 is further arranged to generate, An initial flow occurs when the temperature of the power battery 5 or the coolant is below a threshold temperature, and A second flow rate higher than the first flow rate when the temperature of the power battery 5 or the coolant is higher than said threshold temperature.

[0049] In one example implementation, the threshold temperature is between 43°C and 47°C, typically 45°C.

[0050] The first flow rate can be between 2.8L / min and 3.2L / min, typically 3L / min.

[0051] The second flow rate can be between 5.8L / min and 6.2L / min, typically 6L / min.

[0052] The semi-hybrid vehicle 1 also includes a combustion engine 17, a passenger compartment 18 and a radiator 19 for cooling the combustion engine 17. The cooling radiator 19 is part of the high-temperature cooling circuit and not of the low-temperature cooling circuit 2.

[0053] The low temperature cooling circuit 2 comprises a set of pipes through which the cooling fluid circulates.

[0054] We have seen that the low temperature cooling circuit 2 includes a first conduit 8 formed directly in the casing 6 of the power battery 5.

[0055] The low temperature cooling circuit 2 also includes a second pipe 20 connected at the output of the inverter 4 and at the input of the heat exchanger 3.

[0056] It should be noted that the second duct 20 is opposite the radiator 19 for cooling the internal combustion engine 17, which is located in an accessory panel 21 of the semi-hybrid vehicle 1, and in particular, is transverse to the airflow passing through the radiator 19, either in front of or behind this radiator 19 depending on the direction of airflow. The accessory panel 21 corresponds to the front face of the semi-hybrid vehicle 1. Thus, when the semi-hybrid vehicle 1 is moving, the ambient air and / or the air from the radiator 19 participate in a heat exchange by convection around the wall of the second duct 20, and therefore contributes to cooling the coolant flowing through the second duct 20.

[0057] In addition, the low-temperature cooling circuit 2 includes: A third pipe 22 connected to the heat exchanger 3 and to the pump 16, the pump 16 being disposed between the internal combustion engine 17 and the passenger compartment 18 of the semi-hybrid vehicle 1; A fourth pipe 23 connected to the pump 16 and to the first pipe 8 provided in the casing 6 of the power battery 5; A fifth pipe 24 connected to the first pipe 8 and to the converter 15; and A sixth conduit 25 connected to converter 15 and inverter 4.

[0058] It should be noted that the low-temperature cooling circuit 2 contains a specific volume of coolant designed to limit the coolant temperature rise to +5°C during an electric driving phase lasting between 55 and 65 seconds, typically 60 seconds. This volume can range from 1.7 liters to 1.9 liters, typically 1.8 liters. This quantity provides sufficient heat capacity to limit the temperature rise to 5°C between the beginning and end of a 60-second electric driving phase.

[0059] In one example implementation, the coolant is composed of 50% water and 50% glycol.

[0060] The various aspects of the invention mentioned above offer numerous advantages. Among these are: To improve the cooling of the coolant in a low-temperature cooling system; and Reduce the cost and size of the low-temperature cooling circuit by removing the radiator that usually equips this type of low-temperature cooling circuit.

Claims

CLAIMS

1. Semi-hybrid vehicle (1) comprising a low-temperature cooling circuit (2) passing through a heat exchanger (3) arranged to cool a cooling fluid of said low-temperature cooling circuit (2), an inverter (4) of an electric traction machine of said semi-hybrid vehicle (1), a first conduit (8) of a power battery (5) arranged to supply energy to said electric traction machine, a DC-DC converter (15) arranged to recharge a service battery of said semi-hybrid vehicle (1) by means of said power battery (5), and a pump (16) arranged to force a circulation of said cooling fluid in said low-temperature cooling circuit (2),said semi-hybrid vehicle (1) being characterized in that said low-temperature cooling circuit (2) comprises a second pipe (20) connected to the output of said inverter (4) and to the input of said heat exchanger (3), said second pipe (20) being opposite a radiator (19) for cooling a heat engine (17) arranged in an accessory facade (21) of said semi-hybrid vehicle (1) and in that said low-temperature cooling circuit (2) contains a volume of coolant defined to limit an increase in temperature of said coolant to +5°C during an electric driving phase of between 55 and 65 seconds.,

2. Semi-hybrid vehicle (1) according to the preceding claim, characterized in that the coolant has a volume of between 1.7 liters and 1.9 liters. [Claim s] Semi-hybrid vehicle (1) according to any one of the preceding claims, characterized in that the coolant is composed of 45% to 55% water and 45% to 55% glycol.

4. Semi-hybrid vehicle (1) according to any one of the preceding claims, characterized in that the pump (16) is arranged to generate, A first flow rate when the temperature of the power battery (5) or the coolant is below a threshold temperature; and - A second flow rate higher than said first flow rate when the temperature of said power battery (5) or said coolant is higher than said threshold temperature. [Claim s] Semi-hybrid vehicle (1) according to any one of the preceding claims, characterized in that the power battery (5) has a thermal resistance of less than 0.05 K / W.

6. Semi-hybrid vehicle (1) according to any one of the preceding claims, characterized in that the power battery (5) has a chemistry comprising a cobalt content of between 30 and 35%.

7. Semi-hybrid vehicle (1) according to any one of the preceding claims, characterized in that the power battery (5) comprises a casing (6) provided with a wall (9) in which the first conduit (8) is arranged.

8. Semi-hybrid vehicle (1) according to the preceding claim, characterized in that the casing (6) contains cells (7), each cell (7) comprising an electrolyte (14) completely filling said cell (7).

9. Semi-hybrid vehicle (1) according to the preceding claim, characterized in that each cell (7) comprises cell walls (11) whose thickness is between 1.8 mm and 2.2 mm.

10. Semi-hybrid vehicle (1) according to the preceding claim, characterized in that each cell (7) comprises an electrical insulator (12) arranged between a winding (13) of said cell (7) and the cell walls (11), said electrical insulator (12) being formed by a polyimide.

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