CONTROL OF THE COOLING OF THE LUBRICATING OIL OF AN ELECTRIC VEHICLE DRIVE

Abstract

A control device (DC) equips a vehicle (V) comprising an electric prime mover (MME) supplied with lubricating oil by a first circuit (C1) connected to a lubricating oil / heat transfer fluid exchanger (EC), and an inverter (OM) electrically supplying the prime mover (MME) and cooled by the heat transfer fluid before it reaches the exchanger (EC) via an intermediate part (PI1) of a second circuit (C2). This device (DC) comprises a valve (VC) comprising an inlet (EV) and a first outlet (SV1) connected to two sub-parts (SP1, SP2) of this intermediate part (PI), and a second outlet (SV2) connected to a bypass pipe (CC) connected to the second circuit (C2) downstream of the exchanger (EC), the heat transfer fluid being directed towards the first (SV1) or second (SV2) outlet when a first value representative of a temperature of the lubricating oil is higher or lower than a chosen threshold. Figure 1

Description

Title of the invention: CONTROL OF THE COOLING OF THE LUBRICATING OIL OF AN ELECTRIC DRIVE MACHINE OF A VEHICLE Technical field of the invention

[0001] The invention relates to vehicles comprising a powertrain comprising at least one electric motor, and more specifically to the control of the cooling of the lubricating oil of such a motor. State of the art

[0002] Certain vehicles, possibly land-based (and for example of the automobile type), comprise a powertrain (or GMP) comprising at least one electric motor capable of providing engine torque to move them and an inverter.

[0003] It will be noted that the invention relates not only to purely electric GMPs but also to hybrid GMPs (thermal and electric).

[0004] Generally, the electric motor is supplied with lubricating oil by a first circuit which is connected to an exchanger capable of inducing an exchange of calories between this lubricating oil and a heat transfer fluid circulating in a second (cooling) circuit, and the inverter is capable of electrically supplying this motor and of being cooled by the heat transfer fluid before it reaches the exchanger via an intermediate part of the second circuit.

[0005] A main disadvantage of this mode of operation lies in the fact that, when the electric motor of the vehicle is put into operation, the lubricating oil which supplies it is very slow to heat up because it is continuously cooled in the exchanger by the heat transfer fluid circulating in the second circuit after having cooled the inverter. As a result, when the vehicle is started, the cooled lubricating oil continues to have a “high” viscosity and therefore the lubrication of the electric motor is quite poor because the latter struggles to reduce friction losses, which causes a reduction in its energy efficiency and therefore a reduction in the vehicle’s mileage range.

[0006] The invention therefore aims in particular to improve the situation. Presentation of the invention

[0007] For this purpose, it proposes in particular a control device intended to equip a vehicle comprising:

[0008] - an electric motor machine supplied with lubricating oil by a first circuit connected to an exchanger capable of inducing an exchange of calories between this lubricating oil and a heat transfer fluid circulating in a second circuit, and

[0009] - an inverter suitable for electrically supplying this motor machine and for being cooled by the heat transfer fluid before it reaches the exchanger via an intermediate part of the second circuit.

[0010] This control device is characterized by the fact that it comprises:

[0011] - a valve comprising an inlet and a first outlet suitable for being connected respectively to two sub-parts of the intermediate part of the second circuit, and a second outlet connected to a bypass conduit suitable for being connected to the second circuit downstream of the exchanger, and

[0012] - a control module capable of controlling the valve so that it directs the fluid heat transfer fluid to the first outlet or the second outlet depending on whether a first value representative of a temperature of the lubricating oil is greater than or less than or equal to a chosen threshold.

[0013] Thanks to the invention, the lubricating oil is no longer cooled when it is not necessary, which makes it possible to reduce its viscosity more quickly, and thus to improve the lubrication of the electric motor and therefore its energy efficiency and consequently also the mileage range of the vehicle.

[0014] The control device according to the invention may include other characteristics which may be taken separately or in combination, and in particular:

[0015] - the threshold can be chosen according to a type of the first value;

[0016] - in the presence of the first option, the type can be chosen between an average value of at least two raw temperatures measured at at least two locations distant from the first circuit, and one raw temperature measured at one location of the first circuit;

[0017] - its control module can be arranged, when the first value is greater than a sum of a second value and a third value or where the first value is less than a difference between that second value and a fourth value, to use a chosen threshold equal to that second value;

[0018] - its control module can be arranged, when the first value is greater or equal to a second value and less than or equal to a sum of that second value and a third value, to use a chosen threshold equal to that sum of the second and third values, or, when the first value is less than or equal to that second value and greater than or equal to a difference between that second value and a fourth value, to use a chosen threshold equal to that difference between the second and fourth values;

[0019] - in the presence of one of the last two options, each of the third and fourth values ​​can be between 1°C and 3°C.

[0020] The invention also provides a vehicle, possibly of the automobile type, and comprising:

[0021] - an electric motor machine supplied with lubricating oil by a first circuit connected to an exchanger capable of inducing an exchange of calories between this lubricating oil and a heat transfer fluid circulating in a second circuit,

[0022] - an inverter suitable for electrically supplying this driving machine and for being cooled by the heat transfer fluid before it reaches the exchanger via an intermediate part of the second circuit, and

[0023] - a control device of the type presented above.

[0024] For example, this vehicle may also include a reducer capable of receiving engine torque delivered by the prime mover and supplied with lubricating oil by the first circuit.

[0025] Also for example, the second circuit may comprise a radiator installed downstream of the exchanger after a connection of the bypass conduit to the second circuit, and capable of cooling the heat transfer fluid. Brief description of the figures

[0026] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0027] [Fig.l] schematically and functionally illustrates an exemplary embodiment of a vehicle comprising a control device according to the invention, a cooling circuit, and an electric GMP associated with a supervision computer, and

[0028] [Fig.2] schematically and functionally illustrates an exemplary embodiment of a supervision computer comprising an exemplary embodiment of a control device according to the invention. Detailed description of the invention

[0029] The invention aims in particular to propose a control method, and an associated DC control device, intended to enable control of the cooling of the lubricating oil of at least one electric motor MME of a powertrain (or GMP) of a vehicle V.

[0030] In the following, it is considered, by way of non-limiting example, that the vehicle V is of the automobile type. It is for example a car. But the invention is not limited to this type of vehicle. It relates in fact to any type of vehicle (land, sea (or river) or air) comprising a powertrain (or GMP) comprising at least one electric motor capable of providing engine torque to move it, and a cooling circuit.

[0031] Furthermore, it is considered in the following, by way of non-limiting example, that the vehicle V comprises a powertrain (or GMP) of the all-electric type (and therefore whose drive is provided exclusively by an electric motor MME). But the GMP could be of the hybrid type (thermal and electric).

[0032] Furthermore, it is considered in the following, by way of non-limiting example, that the electric motor MME is supplied with electrical energy by a main (or “traction” or even “power”) battery BP, rechargeable during recharging phases (external or by internal torque recovery). But the electric motor MME could be supplied with electrical energy by a fuel cell.

[0033] [Fig.l] schematically shows a vehicle V comprising an electric GMP (and therefore an electric motor MME), an inverter OM, a reducer RD, a main battery (or traction or power) BP, a supervision computer CS, a first circuit Cl, a second (cooling) circuit C2, and a control device DC according to the invention.

[0034] The GMP is part of a transmission chain, and is, here, purely electric. It therefore comprises at least one electric motor MME arranged to provide engine torque to move the vehicle V when it is electrically powered (in alternating voltage and current) by the inverter OM from the direct electrical energy stored (here) in the main battery BP.

[0035] The operation of the GMP is supervised by a CS supervision computer.

[0036] The main battery BP may, for example, comprise electrical energy storage cells, possibly electrochemical (for example of the lithium-ion (or Li-ion) or Ni-Mh or Ni-Cd type). Also for example, the main battery BP may be of the low voltage type (typically 450 V for illustration purposes). But it could be of the medium voltage or high voltage type.

[0037] The electric motor MME is here coupled, via a reducer RD, to a transmission shaft which is itself coupled to at least one set of driving wheels of the vehicle V, preferably via a differential. For example, this set can be located in the front part of the vehicle V. But it could be located in the rear part of the vehicle V.

[0038] Furthermore, and as illustrated in [Fig.l], the electric motor MME is supplied with lubricating oil by the first circuit C1, which is connected to an exchanger EC capable of inducing an exchange of calories between this lubricating oil and a heat transfer fluid circulating in the second (cooling) circuit C2. It will be noted that in the example illustrated non-limitingly in [Fig.l] the first circuit C1 also supplies the reducer RD with lubricating oil. But this is not an obligation.

[0039] It will also be noted that in the example illustrated non-limitingly in [Fig.l] the first circuit C1 also comprises a reservoir RH storing and collecting the lubricating oil, a filter FH, and a pump PH sucking the lubricating oil from the reservoir RH to inject it, via the filter FH, into the exchanger EC. The latter (EC) comprises a first output which supplies a part of the first circuit Cl which is (here) connected to the reducer RD to supply it with lubricating oil, and the first circuit Cl comprises another part which interconnects an output of the reducer RD to an input of the electric motor MME in order to supply the latter (MME) with lubricating oil. The latter then circulates in another part of the first circuit Cl which supplies the reservoir RH.

[0040] Also as illustrated in [Fig.l], the inverter OM is capable of being cooled by the heat transfer fluid before it reaches the exchanger EC via a first intermediate part PII of the second circuit C2.

[0041] For example, and as illustrated non-limitingly in [Fig.l], the second circuit C2 may comprise a radiator RR installed downstream of the exchanger EC, after the connection J of a bypass conduit CC (to which we will return later) to the second circuit C2, and suitable for cooling the heat transfer fluid. In this case, the second circuit C2 may comprise a second intermediate part PI2 interconnecting (directly or indirectly) a second output of the exchanger EC to the radiator RR, and yet another intermediate part interconnecting (directly or indirectly) an output of the radiator RR to an input of the inverter OM.

[0042] It will be noted that the second circuit C2 can be dedicated to the cooling of the inverter OM and the lubricating oil. But this is not obligatory. Indeed, it could also be used to cool at least one other piece of equipment or component of the vehicle V.

[0043] Also as illustrated in [Fig.l], the DC control device comprises at least one three-way type valve VC, the bypass conduit CC and a control module MC.

[0044] The valve VC comprises an EV inlet and first SV1 and second SV2 outputs. The EV inlet and the first output SV1 are suitable for being connected respectively to two first SP1 and second SP2 sub-parts of the first intermediate part PII of the second circuit C2. The second output SV2 is connected, downstream of the exchanger EC, to the bypass conduit CC which is suitable for being connected to the second circuit C2 (at the connection J which is here located in the second intermediate part PI2 of the second circuit C2). The valve VC can therefore be placed in a first state in which it directs the heat transfer fluid received at its EV inlet to its first SV1 outlet, or in a second state in which it directs the heat transfer fluid received at its EV inlet to its second SV2 outlet.

[0045] For example, the connection J can be made by means of a Y connector mounted on the second intermediate part PI2 of the second circuit C2.

[0046] The control module MC is capable of controlling the valve VC so that it directs the heat transfer fluid either towards the first outlet SV1 when a first value vl representative of a lubricating oil temperature is greater than a chosen threshold st, or towards the second output SV2 when this first value vl is less than or equal to the chosen threshold st.

[0047] In other words, when the first value vl is greater than the chosen threshold st (i.e. vl > st), the control module MC causes the valve VC to be placed in its first state so that the heat transfer fluid circulates in the second sub-part SP1 of the first intermediate part PII of the second circuit C2 to reach the exchanger EC. On the other hand, when the first value vl is less than or equal to the chosen threshold st (i.e. vl < st), the control module MC causes the valve VC to be placed in its second state so that the heat transfer fluid circulates in the bypass conduit CC to directly reach (here) the second intermediate part PI2 of the second circuit C2 (at the connection J), without passing through the exchanger EC (“bypass” mode).

[0048] Thus, it is now possible not to proceed with the cooling of the lubricating oil when the first value vl (representative of its current temperature) is less than or equal to the chosen threshold st. This allows the lubricating oil to heat up more quickly (because it is no longer temporarily cooled in the exchanger EC by the heat transfer fluid), and therefore to reduce its viscosity more quickly, thus improving the lubrication of the electric motor MME and therefore its energy efficiency and consequently also the mileage range of the vehicle V, in particular when starting the latter (V).

[0049] For example, and as illustrated non-limitingly in [Fig. 2], the DC control device may comprise at least one processor PR1, for example a digital signal processor (or DSP (“Digital Signal Processor”)), and at least one memory MD. This DC control device may therefore be produced in the form of a combination of electrical or electronic circuits or components (or “hardware”) and software modules (or “software”). For example, it may be a microcontroller.

[0050] The memory MD is RAM in order to store instructions for the implementation by the processor PR1 of a computer routine or a control computer program. The processor PR1 may comprise integrated (or printed) circuits, or several integrated (or printed) circuits connected by wired or wireless connections. An integrated (or printed) circuit is understood to mean any type of device capable of carrying out at least one electrical or electronic operation.

[0051] In the example illustrated non-limitingly in Figures 1 and 2, the control device DC is part of the supervision computer CS. But this is not obligatory. Indeed, the control device DC could comprise its own dedicated computer, which can then be coupled to the supervision computer CS, or could be part of another computer providing at least one other function within of vehicle V.

[0052] It will be noted, as illustrated non-limitingly in [Fig. 2], that the supervision computer CS (or the computer of the control device DC) can also comprise a mass memory MM1, in particular for storing each measured temperature or each first value vl, as well as any intermediate data involved in all its calculations and processing. Furthermore, this supervision computer CS (or the computer of the control device DC) can also comprise an input interface IE for receiving at least each measured temperature or each first value vl to use it in calculations or processing, possibly after having shaped and / or demodulated and / or amplified it, in a manner known per se, by means of a digital signal processor PR2.In addition, this supervision calculator CS (or the calculator of the control device DC) can also include an output interface IS, in particular to deliver each message (or order) intended to place the valve VC in its first or second state.

[0053] For example, the threshold st can be chosen according to a type of the first value vl. Indeed, the first value vl can be obtained in different ways, which can influence the choice of the chosen threshold st.

[0054] Thus, the type of the first value vl can, for example, be chosen between an average value of at least two raw temperatures which are measured by temperature sensors at at least two distant locations of the first circuit C1, and a raw temperature measured at a single location of the first circuit C1 by a single temperature sensor. In this latter choice, the value of the chosen threshold st can vary substantially depending on the location of the first circuit C1 where the temperature sensor makes its measurement.

[0055] But in an alternative embodiment the value of the chosen threshold st could be fixed (or constant). For example, it (st) could be between 45°C and 55°C. As an illustrative example, it (st) could be equal to 50°C.

[0056] It will be noted that in order to avoid (very) frequent changes in the state in which the valve VC is placed when the first value vl oscillates around the chosen threshold st, a change of state can be delayed as explained below.

[0057] For example, the control module MC can be arranged, when the first value vl is greater than the sum of a second value v2 and a third value v3 (i.e. vl > v2 + v3) or when the first value vl is less than the difference between the second value v2 and a fourth value v4 (i.e. vl < v2 - v4), to use a chosen threshold st which is equal to the second value v2. It will be noted that the third v3 and fourth v4 values ​​are very small compared to the second value v2.

[0058] Also for example, the control module MC can be arranged:

[0059] - when the first value vl is greater than or equal to the second value v2 and in less than or equal to the sum of the second value v2 and the third value v3 (i.e. v2 < vl < v2 + v3), to use a chosen threshold st which is equal to this sum of the second v2 and third v3 values ​​(i.e. st = v2 + v3), or

[0060] - when the first value vl is less than or equal to the second value v2 and su less than or equal to the difference between the second value v2 and the fourth value v4 (i.e. v2 - v4 < vl < v2), to use a chosen threshold st which is equal to this difference between the second v2 and fourth v4 values ​​(i.e. st = v2 - v4).

[0061] It will be noted that the third v3 and fourth v4 values ​​are also very small here compared to the second value v2.

[0062] It will also be noted that the second value v2 can, for example and like the threshold st, be chosen according to the type of the first value vl. But it (v2) can also be fixed (or constant). For example, it could be between 45°C and 55°C. As an illustrative example, it (v2) could be equal to 50°C.

[0063] Also for example, each of the third v3 and fourth v4 values ​​may be between 1°C and 3°C. As an illustrative example, the third v3 and fourth v4 values ​​may be equal to 2°C. But other values ​​may be used for the third v3 and fourth v4 values. In particular, the third v3 and fourth v4 values ​​may be different from each other.

Claims

Claims

1. Control device (DC) for a vehicle (V) comprising i) an electric prime mover (MME) supplied with lubricating oil by a first circuit (Cl) connected to an exchanger (EC) capable of inducing an exchange of calories between said lubricating oil and a heat transfer fluid circulating in a second circuit (C2), and ii) an inverter (OM) capable of electrically supplying said prime mover (MME) and of being cooled by said heat transfer fluid before it reaches said exchanger (EC) via an intermediate part (PII) of said second circuit (C2), characterized in that it comprises a) a valve (VC) comprising an inlet (EV) and a first outlet (SV1) suitable for being connected respectively to two sub-parts (SP1, SP2) of said intermediate part (PII), and a second outlet (SV2) connected to a bypass conduit (CC) suitable for being connected to said second circuit (C2) downstream of said exchanger (EC),and b) a control module (MC) capable of controlling said valve (VC) so that it directs said heat transfer fluid towards said first outlet (SV1) or said second outlet (SV2) depending on whether a first value representative of a temperature of said lubricating oil is greater than or less than or equal to a chosen threshold.,

2. Control device according to claim 1, characterized in that said threshold is chosen as a function of a type of said first value.

3. Control device according to claim 2, characterized in that said type is chosen between an average value of at least two raw temperatures measured at at least two locations distant from said first circuit (Cl), and a raw temperature measured at one location of said first circuit (Cl).

4. Control device according to one of claims 1 to 3, characterized in that said control module (MC) is arranged, when said first value is greater than a sum of a second value and a third value or when said first value is less than a difference between said second value and a fourth value, to use a chosen threshold equal to said second value.

5. Control device according to one of claims 1 to 3, characterized in that said control module (MC) is arranged, when said first value is greater than or equal to a second value and less than or equal to a sum of said second value and a third value, to use a chosen threshold equal to said sum of the second and third values, or, when said first value is less than or equal to said second value and greater than or equal to a difference between said second value and a fourth value, to use a chosen threshold equal to said difference between said second and fourth values.

6. Control device according to claim 4 or 5, characterized in that each of said third and fourth values ​​is between 1°C and 3°C.

7. Vehicle (V) comprising i) an electric motor (MME) supplied with lubricating oil by a first circuit (Cl) connected to an exchanger (EC) capable of inducing an exchange of calories between said lubricating oil and a heat transfer fluid circulating in a second circuit (C2), and ii) an inverter (OM) capable of electrically supplying said motor (MME) and of being cooled by said heat transfer fluid before it reaches said exchanger (EC) via an intermediate part (PII) of said second circuit (C2), characterized in that it further comprises a control device (DC) according to one of claims 1 to 6.

8. Vehicle according to claim 7, characterized in that it comprises a reducer (RD) capable of receiving a motor torque delivered by said prime mover (MME) and supplied with lubricating oil by said first circuit (Cl).

9. Vehicle according to claim 7 or 8, characterized in that said second circuit (C2) comprises a radiator (RR) installed downstream of said exchanger (EC) after a connection (J) of said bypass duct (CC) to said second circuit (C2), and suitable for cooling said heat transfer fluid.

10. Vehicle according to one of claims 7 to 9, characterized in that it is of the automobile type.

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