CONTROL OF THE COOLING OF THE LUBRICATING OIL OF AN ELECTRIC VEHICLE'S DRIVEMACHINE

Abstract

A control device (DC) equips a vehicle (V) comprising an electric drive machine (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 drive machine (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) includes 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 conduit (CC) connected to the second circuit (C2) downstream of the heat exchanger (EC). The heat transfer fluid is diverted to the first (SV1) or second (SV2) outlet when a first representative value of the lubricating oil temperature is above or below a chosen threshold. Figure 1

Description

Title of the invention: CONTROL OF THE COOLING OF THE LUBRICATING OIL OF AN ELECTRIC VEHICLE'S POWERTRAIN Technical field of the invention

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

[0002] Some vehicles, possibly land vehicles (and for example of the automobile type), include a powertrain (or PMT) comprising at least one electric motive machine capable of providing motor torque to move them and an inverter.

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

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

[0005] A major drawback of this operating mode is that, when the vehicle's electric drive unit is started, the lubricating oil supplying it heats up very slowly because it is continuously cooled in the heat exchanger by the heat transfer fluid circulating in the second circuit after cooling the inverter. Consequently, when the vehicle starts, the cooled lubricating oil still has a high viscosity, and therefore the lubrication of the electric drive unit is quite poor because it struggles to reduce friction losses, resulting in a decrease in its energy efficiency and thus a reduction in the vehicle's driving range.

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

[0007] In particular, it proposes for this purpose a control device intended to be fitted to a vehicle comprising:

[0008] - an electric drive machine supplied with lubricating oil by a first circuit connected to a heat exchanger designed to induce a heat exchange between this lubricating oil and a heat transfer fluid circulating in a second circuit, and

[0009] - an inverter suitable for electrically powering this drive 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 connection respectively to two sub-parts of the intermediate section of the second circuit, and a second outlet connected to a bypass conduit designed to be connected to the second circuit downstream of the exchanger, and

[0012] - a control module for 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 representative value of a lubricating oil temperature 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 needed, which allows its viscosity to decrease more quickly, and thus improves the lubrication of the electric drive machine 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 features 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 this second value and a fourth value, to use a chosen threshold equal to this 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 range between 1°C and 3°C.

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

[0021] - an electric drive machine supplied with lubricating oil by a first a circuit connected to a heat exchanger designed to induce a heat exchange between this lubricating oil and a heat transfer fluid circulating in a second circuit,

[0022] - an inverter suitable for electrically supplying this drive machine and for being cooled by the heat transfer fluid before it reaches the heat 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 suitable for receiving motor torque delivered by the driving machine and supplied with lubricating oil by the first circuit.

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

[0026] Other features and advantages of the invention will become apparent from an examination of the detailed description below, and the accompanying drawings, in which:

[0027] [Fig. 1] schematically and functionally illustrates an example of an embodiment of a vehicle comprising a control device according to the invention, a cooling circuit, and an electric powertrain associated with a supervisory computer, and

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

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

[0030] In what follows, vehicle V is considered, by way of non-limiting example, to be of the automobile type. For example, it is a car. However, 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 PWM) including at least one electric motor capable of providing engine torque to propel it, and a cooling circuit.

[0031] Furthermore, in what follows, by way of non-limiting example, vehicle V is considered to comprise an all-electric powertrain (or PMT) (and therefore its propulsion is provided exclusively by an electric motor MME). However, the PMT could be of the hybrid type (thermal and electric).

[0032] Furthermore, in the following, by way of non-limiting example, it is assumed that the electric drive machine MME is supplied with electrical energy by a main (or "traction" or "power") battery BP, rechargeable during charging phases (external or by internal torque recovery). However, the electric drive machine MME could also be supplied with electrical energy by a fuel cell.

[0033] A vehicle V comprising an electric GMP (and therefore an electric motive machine MME), an inverter OM, a reducer RD, a main (or traction or power) battery BP, a supervisory computer CS, a first circuit Cl, a second (cooling) circuit C2, and a DC control device according to the invention is schematically represented in [Fig.1].

[0034] The GMP is part of a transmission chain, and is, here, purely electric. It therefore includes at least one electric drive machine MME arranged to provide motor 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 supervisory computer.

[0036] The main battery BP may, for example, include electrical energy storage cells, possibly electrochemical (e.g., 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 by way of illustration). But it could also be of the medium-voltage or high-voltage type.

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

[0038] Furthermore, and as illustrated in [Fig. 1], the electric drive machine MME is supplied with lubricating oil by the first circuit Cl, which is connected to a heat exchanger EC designed to induce a heat exchange between this lubricating oil and a heat transfer fluid circulating in the second (cooling) circuit C2. It should be noted that in the example illustrated, but not limited to, in [Fig. 1], the first circuit Cl also supplies lubricating oil to the gearbox RD. However, this is not mandatory.

[0039] It should also be noted that in the example illustrated, but not limited to, in [Fig. 1], the first circuit Cl also includes a reservoir RH storing and collecting the lubricating oil, a filter FH, and a pump PH drawing the lubricating oil from the reservoir RH to inject it, via the filter FH, into the heat exchanger EC. The latter (EC) This circuit includes a first output that supplies a portion of the first circuit Cl, which is (here) connected to the gearbox RD to supply it with lubricating oil. The first circuit Cl also includes another portion that interconnects an output of the gearbox RD to an input of the electric motor MME to supply the latter (MME) with lubricating oil. This oil then circulates through another portion of the first circuit Cl, which supplies the reservoir RH.

[0040] Also as illustrated in [Fig.1], the inverter OM is designed to be 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, but not limited to, in [Fig. 1], the second circuit C2 may include a radiator RR installed downstream of the heat exchanger EC, after the connection J of a bypass duct CC (which will be discussed later) to the second circuit C2, and designed to cool the heat transfer fluid. In this case, the second circuit C2 may include a second intermediate section PI2 interconnecting (directly or indirectly) a second outlet of the heat exchanger EC to the radiator RR, and yet another intermediate section interconnecting (directly or indirectly) an outlet of the radiator RR to an input of the inverter OM.

[0042] It should be noted that the second circuit C2 can be dedicated to cooling the inverter OM and the lubricating oil. However, this is not mandatory. 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.1], the DC control device includes at least one three-way type VC valve, the CC bypass conduit and an MC control module.

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

[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 MC control module is designed to control the VC valve so that it directs the heat transfer fluid either to the first outlet SV1 when a first The value vl representing a temperature of the lubricating oil is greater than a chosen threshold st, either 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-section SP1 of the first intermediate section PII of the second circuit C2 to reach the heat exchanger EC. Conversely, 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 duct CC to directly reach (here) the second intermediate section PI2 of the second circuit C2 (at connection J), without passing through the heat 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 decrease its viscosity more quickly, thus improving the lubrication of the electric drive machine 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, but not limited to, in [Fig. 2], the DC control device may include at least one PR1 processor, for example, a digital signal processor (or DSP), and at least one MD memory. This DC control device may therefore be implemented as 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 MD memory is random access memory (RAM) for storing instructions for the implementation by the PR1 processor of a computer routine or a control computer program. The PR1 processor may include integrated circuits (or printed circuit boards), or several integrated circuits (or printed circuit boards) connected by wired or wireless connections. An integrated circuit (or printed circuit board) is defined as any type of device capable of performing at least one electrical or electronic operation.

[0051] In the example illustrated, but not limited to, Figures 1 and 2, the DC control device is part of the CS supervisory computer. However, this is not mandatory. Indeed, the DC control device could comprise its own dedicated computer, which could then be coupled to the CS supervisory computer, or it could be part of another computer performing at least one other function within of vehicle V.

[0052] It should be noted, as illustrated in Figure 2, that the CS supervisory computer (or the DC control device computer) may also include 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 CS supervisory computer (or the DC control device computer) may also include an input interface IE for receiving at least each measured temperature or each first value vl for use in calculations or processing, possibly after having been shaped and / or demodulated and / or amplified, in a manner known per se, by means of a digital signal processor PR2.Furthermore, this CS supervisory computer (or the DC control device computer) may also include an IS output interface, notably to deliver each message (or command) intended to place the VC valve in its first or second state.

[0053] For example, the threshold st can be chosen according to the type of the first value vl. Indeed, the first value vl can be obtained in different ways, which can influence the choice of the 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 measured by temperature sensors at at least two locations distant from the first circuit Cl, and a raw temperature measured at a single location in the first circuit Cl by a single temperature sensor. In this latter choice, the value of the chosen threshold st can vary substantially depending on the location in the first circuit Cl where the temperature sensor performs its measurement.

[0055] However, in one 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 should be noted that in order to avoid (very) frequent changes in the state in which the VC valve 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 configured, 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 that is equal to the second value v2. Note that the third v3 and fourth v4 values ​​are very small compared to the second value v2.

[0058] Also, for example, the MC control module 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 < v1 < 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 greater 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 should be noted that the third v3 and fourth v4 values ​​are also very small here compared to the second value v2.

[0062] It should 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 ​​can be between 1°C and 3°C. As an illustrative example, the third v3 and fourth v4 values ​​can be equal to 2°C. But other values ​​can be used for the third v3 and fourth v4 values. In particular, the third v3 and fourth v4 values ​​can be different from each other.

Claims

Demands

1. A control device (DC) for a vehicle (V) comprising i) an electric drive machine (MME) supplied with lubricating oil by a first circuit (C1) connected to a heat exchanger (EC) adapted to induce heat exchange between said lubricating oil and a heat transfer fluid circulating in a second circuit (C2), and ii) an inverter (OM) adapted to electrically supply said drive machine (MME) and to be cooled by said heat transfer fluid before it reaches said heat exchanger (EC) via an intermediate portion (PII) of said second circuit (C2), characterized in that it comprises a) a valve (VC) comprising an inlet (EV) and a first outlet (SV1) adapted to be connected respectively to two sub-portions (SP1, SP2) of said intermediate portion (PII), and a second outlet (SV2) connected to a bypass conduit (CC) adapted to be connected to said second circuit (C2) downstream of said heat exchanger (EC),and b) a control module (CM) suitable for controlling said valve (VC) so that it directs said heat transfer fluid to said first outlet (SV1) or said second outlet (SV2) depending on whether a first representative temperature value of said lubricating oil is greater than, less than, or equal to a chosen threshold.

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

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

4. Control device according to any one of claims 1 to 3, characterized in that said control module (CM) 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. A control device according to any one of claims 1 to 3, characterized in that said control module (CM) 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 drive machine (MME) supplied with lubricating oil by a first circuit (Cl) connected to a heat exchanger (EC) adapted to induce a heat exchange between said lubricating oil and a heat transfer fluid circulating in a second circuit (C2), and ii) an inverter (OM) adapted to electrically supply said drive machine (MME) and to be cooled by said heat transfer fluid before it reaches said heat exchanger (EC) via an intermediate part (PII) of said second circuit (C2), characterized in that it further comprises a control device (DC) according to any one of claims 1 to 6.

8. Vehicle according to claim 7, characterized in that it comprises a reducer (RD) adapted to receive a motor torque delivered by said driving machine (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 any one of claims 7 to 9, characterized in that it is of the automobile type.

Images