Lubricant circuit of electric vehicle drive unit

Abstract

To provide a lubricant circuit in an electric vehicle drive unit with a charging mechanism, in which a motor of the electric vehicle drive unit is incorporated as a boost circuit, and a motor and a relay box connected to each other, capable of achieving simplification of the cooling circuit and miniaturization of the cooling structure.SOLUTION: A lubricating oil used for motor 1 satisfies that the kinematic viscosity at 40°C is 13 mm2 / sec or less, and the lubricating oil can be supplied to a piping connecting motor 1 and relay box 8.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lubricating oil circuit for an electric vehicle drive unit that integrates components such as a motor, gears (reduction gears), and an inverter. [Background technology]

[0002] In an electric vehicle (also referred to as an electric motor vehicle), there is known an electrical system cooling system which includes a drive motor (also simply referred to as a motor) that generates driving force for running the vehicle using battery power, an inverter that is interposed between the drive motor and the battery and controls the rotation of the drive motor, a converter that reduces the battery voltage to a predetermined low voltage which is supplied to each of the charger and the inverter to enable their operation, and the charger which includes an electric pump that circulates a coolant, and in which the charger and the like are arranged in series with a cooling circuit which is arranged so that they can exchange heat with the coolant (see Patent Document 1 below). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-035089 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a configuration in which the motor of an electric vehicle drive unit is incorporated as a boost circuit in a charging mechanism for an electric vehicle, the relay box and the motor are connected by a wire harness. In this case, if battery cooling water is used to cool the relay box and the wire harness, the cooling circuit becomes complicated and the cooling structure becomes large.

[0005] The present invention has been made in consideration of the above circumstances, and has an object to provide a lubricating oil circuit for an electric vehicle drive unit in which the motor of the electric vehicle drive unit is incorporated as a boost circuit in the charging mechanism of an electric vehicle, and in which it is possible to realize a simplified cooling circuit and a compact cooling structure in the lubricating oil circuit of the electric vehicle drive unit to which the motor and a relay box are connected. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a lubricating oil circuit for an electric vehicle drive unit in a charging mechanism for an electric vehicle, in which the motor of the electric vehicle drive unit is incorporated as a boost circuit and the motor is connected to a relay box, and the lubricating oil used by the motor can be supplied to piping connecting the motor and the relay box. Effect of the Invention

[0007] According to the present invention, the cooling circuit can be simplified by using the electric pump of the motor to cool the relay box. In addition, since the kinetic viscosity of the lubricating oil is low, the line pressure loss in the oil passage to the relay box is small, and the lubricating oil can be supplied by the electric pump mounted on the motor. As a result, the motor of the electric vehicle drive unit can be incorporated as a boost circuit in the charging mechanism of the electric vehicle, and the cooling circuit can be simplified and the cooling structure can be made smaller in the lubricating oil circuit of the electric vehicle drive unit to which the motor and relay box are connected. [Brief description of the drawings]

[0008] [Figure 1] 2 is a schematic diagram showing a circuit configuration of a lubricating oil circuit of an electric vehicle drive unit in the embodiment. FIG. [Diagram 2] FIG. 2 is an example of a control flow diagram of a control device according to the present embodiment. [Diagram 3] FIG. 4 is another example of a control flow diagram of the control device in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, a lubricating oil circuit of an electric vehicle drive unit according to an embodiment of the present invention will be specifically described with reference to the drawings.

[0010] FIG. 1 is a schematic diagram showing the circuit configuration of a lubricating oil circuit of an electric vehicle drive unit in this embodiment. An electric vehicle drive unit (also called an electric axle) 100 in this embodiment is a unit in which components such as a motor 1, a gear (reduction gear) 2, and an inverter (not shown) are integrated (integrated) in an electric vehicle capable of running by driving using electric power. The motor 1 is a well-known motor generator having a motor function and a power generation function. The motor 1 generates a driving force for running the vehicle using electric power from a battery 11. The gear 2 constitutes a power transmission mechanism that transmits the power output from the motor 1, which is the power source of the vehicle, to the wheels (drive wheels). The inverter (not shown) is interposed between the motor 1 and the battery 11 and controls the rotation of the motor 1.

[0011] The electric vehicle drive unit 100 of this embodiment is provided with a charging lid 9 that is connected to a charging facility 10 such as a charging stand as a charging mechanism for the electric vehicle (for the battery 11), and is connected to this charging lid 9 via a relay box 8. In other words, the charging lid 9 and (the motor 1 of) the electric vehicle drive unit 100 connected to the battery 11 are electrically connected via the relay box 8. The (motor 1 of) the electric vehicle drive unit 100 and the relay box 8, and the relay box 8 and the charging lid 9 are electrically connected by wire harnesses (W / H) 8a, 9a, respectively. In the charging mechanism for an electric vehicle configured in this way, the motor 1 of the electric vehicle drive unit 100 is incorporated as a boost circuit.

[0012] 1, the electric vehicle drive unit 100 of this embodiment includes a lubricating oil circuit 200 that circulates lubricating oil (hereinafter, may be referred to as electric vehicle oil or simply oil). The lubricating oil circuit 200 includes a first circuit 210 for cooling the motor 1 and lubricating the gear 2, and a second circuit 220 for cooling the relay box 8.

[0013] In detail, the lubricant oil circuit 200 has a structure that connects an oil passage that supplies oil as a refrigerant to the relay box 8 with an oil passage that supplies oil to parts within the electric vehicle drive unit 100 that need to be cooled and parts that need to be lubricated.

[0014] Furthermore, the electric vehicle drive unit 100 pumps oil in the lubricant oil circuit 200 toward the supply destination by means of one electric pump 5. The electric pump 5 is driven by an electric motor (not shown). The electric motor is driven under the control of a control device (ECU) 110. The control device 110 is configured by a well-known electronic control device, and drives and controls the electric pump 5. The electric pump 5 is driven under the control of the control device 110, and sucks oil stored in the oil reservoir 4 through the strainer 3 and discharges it from the discharge port. The oil discharged from the electric pump 5 (its discharge port) is pumped through the lubricant oil circuit 200 toward the downstream side by the discharge pressure of the electric pump 5.

[0015] Furthermore, the electric vehicle drive unit 100 cools the oil discharged from the electric pump 5 by one heat exchanger 6. The heat exchanger 6 is a heat exchanger that exchanges heat between the cooling water and the oil flowing through the lubricant oil circuit 200. That is, in this example, the heat exchanger 6 is a water-cooled oil cooler. The cooling water may also be used to cool an inverter (not shown).

[0016] [1st circuit] The first circuit 210 has an electric pump 5, a heat exchanger 6, a switching valve 7, a motor 1, and a gear 2. In detail, the first circuit 210 has a cooling circuit 211 for cooling the motor 1 and a lubrication circuit 212 for lubricating the gear 2.

[0017] The cooling circuit 211 has an electric pump 5, a heat exchanger 6, a switching valve 7, and a motor 1. The cooling circuit 211 cools (water-cools) the oil discharged from the electric pump 5 in the heat exchanger 6, and then supplies the oil to the motor 1. That is, in the cooling circuit 211, the oil that has passed through the heat exchanger 6 is supplied to the motor 1, which is a part that requires cooling.

[0018] The lubrication circuit 212 has an electric pump 5, a heat exchanger 6, a switching valve 7, and a gear 2. In the lubrication circuit 212, the oil discharged from the electric pump 5 is cooled (temperature adjusted) by the heat exchanger 6, and then the oil is supplied to the gear 2. That is, in the lubrication circuit 212, the oil that has passed through the heat exchanger 6 is supplied to the gear 2, which is a part requiring lubrication.

[0019] In this embodiment, a switching valve 7 is provided between the heat exchanger 6 and the motor 1 in the cooling circuit 211, and between the heat exchanger 6 and the gear 2 in the lubrication circuit 212. In the cooling circuit 211 and the lubrication circuit 212, the oil passages downstream (discharge port side) of the switching valve 7 are branched at a branch point 213 to the motor 1 side and the gear 2 side. Therefore, the oil discharged by the common electric pump 5 and cooled (water-cooled) by the common heat exchanger 6 is pressure-fed to the motor 1 or the gear 2 after passing through the switching valve 7. At that time, the switching valve 7 controls the oil flow direction so that the oil flows directly from the heat exchanger 6 into the motor 1 or the gear 2. Note that a mechanism for controlling the flow rate of oil flowing into the motor 1 and the gear 2 at the branch point 213 may be added.

[0020] After circulating through the first circuit 210 and cooling the motor 1 or lubricating the gear 2, the oil flows into an oil reservoir (also called an oil pan) 4 in which a strainer 3 is disposed.

[0021] [Second circuit] The second circuit 220 has an electric pump 5, a heat exchanger 6, a switching valve 7, a relay box 8, a motor 1, and a gear 2. That is, the second circuit 220 has a configuration in which an oil passage for cooling the relay box 8 (including the wire harness 8a) is added to the first circuit 210. The second circuit 220 supplies the oil discharged from the electric pump 5 and cooled (water-cooled) by the heat exchanger 6 to the relay box 8 before supplying it to the motor 1 and the gear 2. That is, in the second circuit 220, the oil that has passed through the heat exchanger 6 is supplied to the relay box 8.

[0022] The second circuit 220 includes a circuit branched off from the first circuit 210 at the switching valve 7, which is a branch point. As described above, the switching valve 7 is provided between the heat exchanger 6 and the motor 1 and the gear 2, and controls the direction of oil flow between the first circuit 210 and the second circuit 220 (to the relay box 8 in the first circuit 210). As long as the wire harness 8a can be cooled simultaneously as a piping for discharging and supplying oil between the electric vehicle drive unit 100 and the relay box 8, a rubber piping (not shown) connecting them may be separately installed, or the wire harness 8a itself connecting them may be used as a piping (forming an oil passage through which oil flows inside the wire harness 8a). After passing through the switching valve 7, the oil is pumped to the relay box 8 to cool the relay box 8, and in this example, merges with the first circuit 210 downstream of the switching valve 7 and upstream of the motor 1 and the gear 2 (between the switching valve 7 and the motor 1 and the gear 2).

[0023] After circulating through the second circuit 220 and cooling the relay box 8 (including the wire harness 8a), the oil flows into the oil reservoir (oil pan) 4 in which the strainer 3 is disposed.

[0024] The switching valve 7 described above is controlled by the control device 110. The control device 110 executes directional control of the switching valve 7 to control whether oil is caused to flow in the first circuit 210 or the second circuit 220, in other words, whether oil is caused to flow in the relay box 8 as well. For example, when the control device 110 receives an ON signal of the charging flag, the control device 110 controls the switching valve 7 to switch the oil flow direction and operate the electric pump 5 so as to cause oil to flow in the second circuit 220, in other words, to cause oil to flow in the relay box 8 as well. The ON signal of the charging flag may be input, for example, by detecting that the charging plug of the charging equipment 10 and the charging lid 9 are connected, or may be input by detecting that the charging start switch is turned ON after the charging plug of the charging equipment 10 and the charging lid 9 are connected, or may be input after various other safety checks.

[0025] Fig. 2 is an example of a control flow diagram of the control device 110 in this embodiment. As shown in Fig. 2, the control device 110 judges whether the charging flag is ON or not (step S1), and when it is judged that the charging flag is ON (step S1: Yes), it switches the oil flow direction of the switching valve 7 to the relay box 8 side (step S2) and operates the electric pump 5 (step S3). As a result, oil is caused to circulate in the second circuit 220, in other words, oil is caused to circulate in the relay box 8 as well, and the relay box 8 (including the wire harness 8a) is cooled by the oil that has passed through the switching valve 7 via the heat exchanger 6.

[0026] When the control device 110 receives an OFF signal from the charging flag due to completion of charging, etc. (for example, the charging start switch is OFF, the charging plug of the charging equipment 10 is removed from the charging lid 9, etc.), it stops the electric pump 5, switches the oil flow direction of the switching valve 7, and cuts off the flow of oil to the relay box 8 side.

[0027] Fig. 3 is another example of a control flow diagram of the control device 110 in this embodiment. Fig. 3 is obtained by adding steps S11 and S12 between steps S1 and S2 in Fig. 2. In the example shown in Fig. 3, in order to reliably cool the relay box 8 (including the wire harness 8a), it is confirmed in steps S11 and S12 that the temperature of the oil as a coolant (oil temperature) is equal to or lower than a predetermined value. The predetermined value is set to, for example, equal to or lower than the heat generation temperature of the relay box 8 (approximately 50°C).

[0028] After determining that the charging flag is ON (step S1: Yes), the control device 110 determines whether the oil temperature is equal to or lower than a predetermined value (step S11). If it is determined that the oil temperature exceeds the predetermined value (step S11: No), pre-cooling is performed so that the oil temperature is equal to or lower than the predetermined value (step S12). By pre-cooling, the electric pump 5 is operated, and the oil is circulated in the first circuit 210 with the switching valve 7 in the OFF state to the relay box 8, and heat is released from the heat exchanger 6 to the cooling water. Note that, since the motor 1 and the gear 2 do not generate heat while the vehicle is stopped, the oil temperature can be lowered by releasing heat to the cooling water via the heat exchanger 6. On the other hand, if it is determined that the oil temperature is equal to or lower than the predetermined value (step S11: Yes), as described above, the oil flow direction of the switching valve 7 is switched to the relay box 8 side (step S2), the electric pump 5 is operated (step S3), and the relay box 8 (including the wire harness 8a) is cooled with the oil that has passed through the switching valve 7 via the heat exchanger 6.

[0029] When the control device 110 uses the oil temperature to control the direction of the switching valve 7, a sensor (not shown) for detecting the oil temperature is provided on the vehicle, and a signal is input from the sensor to the control device 110.

[0030] In the above embodiment, oil is circulated inside relay box 8, and relay box 8 (including wire harness 8a) is cooled by the oil that has passed through switching valve 7 via heat exchanger 6, but some or all of the oil circulated inside relay box 8 may be circulated inside charging lid 9 to cool charging lid 9 (including wire harness 9a) simultaneously with or after cooling relay box 8. As a piping for discharging and supplying oil between relay box 8 and charging lid 9, a rubber piping (not shown) connecting them may be installed separately as long as the wire harness 9a can be cooled simultaneously, or the wire harness 9a connecting them may itself be used as a piping (forming an oil passage through which oil flows inside wire harness 9a).

[0031] As described above, in a system that performs neutral point charging as shown in Fig. 1, the relay box 8 generates heat due to high voltage. In addition, the wire harness 8a that connects the relay box 8 to the electric vehicle drive unit 100 generates heat. If battery cooling water is used to cool the relay box 8 and the wire harness 8a, problems arise in that the cooling circuit becomes complicated and the cooling structure becomes large.

[0032] In this embodiment, by applying the above-described configuration, cooling of the relay box 8 and the wire harness 8a connected thereto is performed by sharing the components of the electric vehicle drive unit 100 (electric vehicle oil, electric pump 5, heat exchanger 6), thereby simplifying the cooling circuit and reducing the size of the cooling structure.

[0033] In detail, the electric vehicle oil used in the electric vehicle drive unit 100 has a kinetic viscosity of 13 mm at 40°C. 2 / sec or less, and electrical properties (volume resistivity 10 8 Ωcm or more, dielectric breakdown voltage 1.0kV or more, relative dielectric constant 6.0 or less). Kinematic viscosity at 40℃ 13.0mm 2 / sec or less satisfies the necessary requirements for insulation, breakdown voltage, and dielectric constant of the relay box 8 and wire harness 8a, so it is possible to transport the oil from the electric vehicle drive unit 100 to the relay box 8 and to pour it directly over the relay box 8 as a coolant.

[0034] Furthermore, by connecting the relay box 8 to the electric vehicle drive unit 100, a circuit is formed that cools the relay box 8 with the electric vehicle oil used in the electric vehicle drive unit 100. Also, a switching valve 7 for changing the oil path to the relay box 8 is installed between the heat exchanger 6 and the oil path of the motor 1 or the gear 2. Also, the piping for supplying and discharging the electric vehicle oil between the relay box 8 and the electric vehicle drive unit 100 uses rubber piping, or a wire harness 8a connected thereto as piping (a passage is formed inside the wire harness through which the electric vehicle oil flows) (see FIG. 1).

[0035] Furthermore, the supply of oil to the relay box 8 is controlled by a switching valve 7. When the charging flag is turned ON, the switching valve 7 switches the oil flow direction to the circuit to the relay box 8 (see FIG. 2). Furthermore, when performing quick charging after high-speed driving, for example, the oil temperature is high, so it is necessary to reduce the oil temperature to a predetermined value (for example, 50°C) or lower by pre-cooling. Therefore, the oil flow direction may be controlled so that oil flows to the relay box 8 (only) when the oil temperature is below the predetermined value (see FIG. 3).

[0036] As described above, in this embodiment, since the kinetic viscosity of the oil for electric vehicles is low, the pipeline pressure loss in the oil passage to the relay box 8 is small, and the oil can be supplied by the electric pump 5 already installed in the electric vehicle drive unit 100 (the capacity of the electric pump 5 does not need to be increased). In addition, by utilizing the high insulation and high voltage resistance of the oil for electric vehicles, the relay box 8 can be directly cooled with oil, thereby making it possible to reduce the size of the cooling structure. In addition, by using the (single) electric pump 5 provided in the electric vehicle drive unit 100, the cooling circuit can be simplified (lightweight and low cost). In addition, by using the wire harness 8a for the piping for supplying / discharging the oil for electric vehicles from the electric vehicle drive unit 100 to the relay box 8, it is possible to reduce the size (diameter reduction) of the wire harness 8a by oil cooling and simplify the cooling circuit. In addition, by controlling the oil temperature for cooling the oil to the relay box 8 (FIG. 3), optimal cooling performance can be ensured.

[0037] As described above, this embodiment proposes a lubricating oil circuit 200 that utilizes the electric vehicle oil and electric pump 5 used in the electric vehicle drive unit 100 to cool the relay box 8 and wire harness 8a in a system configuration in which the motor 1 of the electric vehicle drive unit 100 is incorporated as a boost circuit in a charging mechanism for an electric vehicle. The switching valve 7 of the lubricating oil circuit 200 is installed after the heat exchanger 6 and before the motor 1, and the switching control of the oil flow direction of the switching valve 7 (whether to flow to the relay box 8 side or not) is performed according to the oil temperature, etc.

[0038] According to this embodiment, the electric pump 5 provided in the motor 1 is used to cool the relay box 8, thereby simplifying the cooling circuit. In addition, because the kinetic viscosity of the lubricating oil is low, the pipeline pressure loss in the oil passage up to the relay box 8 is small, and the lubricating oil can be supplied by the electric pump 5 mounted on the motor 1. As a result, the motor 1 of the electric vehicle drive unit 100 is incorporated as a boost circuit in the charging mechanism of an electric vehicle, and in the lubricating oil circuit 200 of the electric vehicle drive unit 100 to which the motor 1 and relay box 8 are connected, it is possible to realize a simplification of the cooling circuit and a miniaturization of the cooling structure.

[0039] The lubricating oil circuit 200 of the electric vehicle drive unit 100 according to the present invention is not limited to the above-described embodiment, and can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0040] 1 motor, 2 gear, 3 strainer, 4 oil reservoir, 5 electric pump, 6 heat exchanger, 7 switching valve, 8 relay box, 9 charging lid, 8a, 9a wire harness (W / H), 10 charging equipment, 11 battery, 100 electric vehicle drive unit (electric axle), 110 control device (ECU), 200 lubricating oil circuit, 210 first circuit, 211 cooling circuit, 212 lubrication circuit, 220 second circuit

Claims

[Claim 1] A lubricating oil circuit for an electric vehicle drive unit in a charging mechanism for an electric vehicle, the lubricating oil circuit including a motor of the electric vehicle drive unit incorporated as a boost circuit and connected to a relay box, A lubricating oil circuit of an electric vehicle drive unit, capable of supplying lubricating oil used by the motor to a pipe connecting the motor and the relay box.

Images