Control device for vehicle

Abstract

To provide a control device for a vehicle which improves electric consumption, in driving of an electric oil pump.SOLUTION: An electric control device 90 controls driving of an electric oil pump EOP, on the basis of a map VMAP previously set from an atmospheric pressure Pa detected by an atmospheric sensor 94, a coil temperature Tc of stator coils (48, 55) of electric machines (MG1, MG2), and a battery charging amount SOC. Thereby, driving of the electric oil pump EOP including the battery charging amount SOC, specifically, a battery voltage is appropriately controlled, which secures withstand voltages Vins of the stator coils (48, 55) of the electric machines (MG1, MG2), and improves electric consumption, in driving of the electric oil pump EOP.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for cooling an electric motor provided in an electric vehicle. [Background technology]

[0002] Electric motors mounted on electric vehicles and hybrid vehicles are cooled by discharging oil. Regarding cooling by discharging oil, a technology has been disclosed that controls the oil discharged from an electric oil pump according to the atmospheric pressure (altitude) to prevent a decrease in the dielectric strength voltage of the coil of the electric motor. For example, a cooling device described in Patent Document 1 is such a technology. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-22769 Summary of the Invention [Problem to be solved by the invention]

[0004] The dielectric strength of an electric motor's coil is affected not only by changes in atmospheric pressure (altitude) but also by the charge level of the battery that powers the motor. Battery voltage also changes as the charge level of the battery changes. In electric vehicles powered solely by an electric motor, the battery voltage is applied directly to the motor, so changes in this applied voltage also change the required dielectric strength of the coil. For example, when the battery charge level, i.e., battery voltage, is low, the required dielectric strength also decreases, which makes it possible to reduce the frequency of cooling by oil discharge. However, in the past, electric oil pumps were driven without taking this into consideration, leaving room for improvement in terms of fuel economy.

[0005] The present invention has been made in light of the above circumstances, and an object of the present invention is to provide a vehicle control device that can improve the electricity cost when driving an electric oil pump. [Means for solving the problem]

[0006] The gist of the present invention is (a) a control device for a vehicle equipped with an electric motor, a cooling mechanism that cools the electric motor with oil discharged from an electric oil pump, and a battery that supplies and receives power to the electric motor, and (b) the control device controls the operation of the electric oil pump based on a pre-set map of atmospheric pressure detected by an atmospheric pressure sensor, the temperature of the coil of the electric motor, and the charge amount of the battery. [Effects of the Invention]

[0007] According to the present invention, the control device controls the operation of the electric oil pump based on a map that is preset based on the atmospheric pressure detected by the atmospheric pressure sensor, the temperature of the coil of the electric motor, and the charge amount of the battery. As a result, the operation of the electric oil pump is appropriately controlled, including the charge amount of the battery, i.e., the battery voltage, so that the withstand voltage of the coil of the electric motor is ensured and electric fuel efficiency is improved in the operation of the electric oil pump. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram showing a configuration of a vehicle to which the present invention is applied; [Figure 2] FIG. 2 is a schematic diagram showing the structure of a cooling mechanism that cools the electric motor of FIG. 1, and also shows an overview of a control system of an electronic control device that controls an electric oil pump. [Figure 3] 4 is a flowchart for explaining the main control operations of the electronic control device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately. [Example]

[0010] 1 is a schematic diagram showing the configuration of a vehicle 10 to which the present invention is applied. The vehicle 10 is a hybrid vehicle equipped with an engine 12 and a drive unit 14 as power sources, and a pair of left and right drive wheels 16 are driven by power output from the engine 12 and the drive unit 14.

[0011] The engine 12 is a known internal combustion engine such as a gasoline engine. The drive unit 14 includes an input shaft 23, a planetary gear set 24, an electric motor MG1, and an output gear 26, which are rotatable about a first rotational axis CL1. The drive unit 14 also includes a power transmission shaft 34, an electric motor MG2, and a reduction gear 36, which are rotatable about a second rotational axis CL2. The drive unit 14 also includes a countershaft 32, a counter gear 28, and a differential drive gear 30, which are rotatable about a third rotational axis CL3. The drive unit 14 also includes a differential unit 20 and an axle 22, which are rotatable about a fourth rotational axis CL4. All of these rotating members are housed inside a case 40, which is a non-rotating member. The first to fourth rotational axes CL1 to CL4 are all rotational axes that are parallel to the vehicle width direction of the vehicle 10.

[0012] The electric motors MG1 and MG2 are each a known rotating electric machine, a so-called motor generator. The electric motors MG1 and MG2 are connected to a battery (not shown) that supplies and receives power to each of them via an inverter (not shown). The inverter controls the operation of the electric motors MG1 and MG2. The electric motor MG1 includes a cylindrical stator 42 fixed to a case 40 so as not to rotate, a stator coil 48 wound around the stator 42, a cylindrical rotor 44 disposed on the inner periphery of the stator 42, and a rotor shaft 46 connected to the inner periphery of the rotor 44 and rotatably supported within the case 40. The electric motor MG2 has a similar configuration and includes a stator 50, a stator coil 55, a rotor 52, and a rotor shaft 54. The electric motors MG1 and MG2 correspond to the "electric motors" of the present invention.

[0013] The input shaft 23 is connected to the engine 12 via a crankshaft 12a of the engine 12 and a damper (not shown) or the like so as to be capable of transmitting power thereto.

[0014] The planetary gear set 24 is a known single-pinion planetary gear set that includes a sun gear S, a carrier CA, and a ring gear R. The planetary gear set 24 functions as a power distribution mechanism that distributes the power of the engine 12 to the electric motor MG1 and an output gear 26. The sun gear S of the planetary gear set 24 is connected to the electric motor MG1, and the carrier CA is connected to the engine 12 via the input shaft 23 and the crankshaft 12a. The ring gear R is formed integrally with the inner circumferential surface of the output gear 26, and is connected to a counter gear 28 so as to be able to transmit power.

[0015] The counter gear 28 is meshed with the reduction gear 36. The power transmission shaft 34 fixes the reduction gear 36 and the electric motor MG2 so that they cannot rotate relative to each other. The counter shaft 32 fixes the counter gear 28 and the differential drive gear 30 so that they cannot rotate relative to each other. The counter gear 28 is meshed with the output gear 26 and the reduction gear 36, thereby transmitting the power output from the engine 12 and the electric motor MG2. The differential drive gear 30 is meshed with a differential driven gear 38 of the differential device 20, so that the power output from at least one of the engine 12 and the electric motor MG2 is transmitted to the drive wheels 16 via the differential device 20 and the axles 22.

[0016] The case 40 is composed of a first case member 40a, a second case member 40b, and a third case member 40c. The second case member 40b is open on both sides in the direction of the first rotation axis CL1, and the first case member 40a is fastened to one opening of the second case member 40b with a bolt, and the third case member 40c is fastened to the other opening of the second case member 40b with a bolt.

[0017] A partition wall 56 perpendicular to the first rotation axis CL1 is formed in the second case member 40b. The partition wall 56 divides the interior of the case 40 into a gear chamber 58 that houses various gears such as the planetary gear unit 24, the output gear 26, the counter gear 28, the reduction gear 36, and the differential unit 20, and a motor chamber 60 that houses the electric motors MG1 and MG2.

[0018] The drive device 14 includes a cooling mechanism 70 that cools the electric motors MG1 and MG2. The cooling mechanism 70 includes an electric oil pump EOP including the electric motor 64, and a cooling oil passage 84. The drive of the electric oil pump EOP is controlled by an electronic control device 90, which will be described later.

[0019] Fig. 2 is a schematic diagram showing the structure of the cooling mechanism 70, and is a diagram showing the control system of an electronic control device 90 (described later) that controls the electric oil pump EOP. In Fig. 2, the top of the page corresponds to the direction of the vertical line when the vehicle is mounted on a flat road. Note that the structure for cooling the electric motors MG1 and MG2 with oil is the same for both electric motors MG1 and MG2, so Fig. 2 shows only the structure for cooling the electric motor MG1 as a representative diagram, and omits the structure for cooling the electric motor MG2.

[0020] 2 shows a cross-sectional view of a portion of electric motor MG1 housed in motor chamber 60 formed in case 40. Electric motor MG1 includes a stator 42 and a rotor 44, each of which is formed by stacking a plurality of disk-shaped electromagnetic steel plates in the direction of first axis of rotation CL1.

[0021] Stator coils 48 are wound around a plurality of slots, which are grooves formed in the inner periphery of stator 42 and are parallel to first axis of rotation CL1, and coil ends 72 formed by bundling a plurality of stator coils 48 are disposed on both ends of stator 42 in the direction of first axis of rotation CL1. Stator 42 is configured to include stator coils 48 wound around stator 42.

[0022] When electric motor MG1 is driven, stator coil 48 is energized and generates heat. The generated heat is dissipated by being transferred to stator 42 at the points where it is in contact with stator 42, but is difficult to dissipate at coil ends 72 because they are not in contact with stator 42. Cooling mechanism 70 is configured to directly cool stator coil 48 of electric motor MG1 by arranging cooling pipes 74 above electric motor MG1 in the direction of a vertical line when mounted on the vehicle and discharging oil from cooling pipes 74 toward coil ends 72 of electric motor MG1 and directly spraying oil onto coil ends 72.

[0023] The cooling pipe 74 is made of a pipe-shaped member that is open at one end in the longitudinal direction, and is arranged parallel to the first axis of rotation CL1 so that the longitudinal direction is along the first axis of rotation CL1. One end in the longitudinal direction of the cooling pipe 74 is fixed to the partition wall 56 of the second case member 40b with a bolt 76. A protrusion 78 is formed on the other end in the longitudinal direction of the cooling pipe 74, and the protrusion 78 fits into a recess 80 formed in the third case member 40c, thereby suppressing oscillation of the cooling pipe 74.

[0024] Oil is supplied to the cooling pipe 74 from an opening at one end in the longitudinal direction. Oil discharged from the electric oil pump EOP is supplied to the cooling pipe 74. Note that the oil discharged from the electric oil pump EOP may be cooled via an oil cooler (not shown) before being supplied to the cooling pipe 74.

[0025] The cooling pipe 74 is formed with a plurality of cooling oil holes 82 for directly applying oil that has flowed into the cooling pipe 74 to the pair of coil ends 72 of the electric motor MG1. Each cooling oil hole 82 communicates between the inside and outside of the cooling pipe 74, and its opening is formed in a position facing the pair of coil ends 72 of the electric motor MG1. Specifically, each cooling oil hole 82 is formed in the same position as the pair of coil ends 72 in the longitudinal direction of the cooling pipe 74 (i.e., the direction of the first rotation axis CL1). In other words, when each cooling oil hole 82 is viewed in the radial direction centered on the first rotation axis CL1, each cooling oil hole 82 is formed in a position overlapping the pair of coil ends 72. By forming the cooling oil holes 82 in the above positions, oil that has flowed into the cooling pipe 74 is discharged from the opening of the cooling oil holes 82 toward the pair of coil ends 72, as shown by the arrows in FIG. 2 . Accordingly, the oil discharged from the cooling oil holes 82 is directly applied to the coil ends 72. The cooling pipe 74 and the cooling oil holes 82 formed in the cooling pipe 74 form a cooling oil passage 84 for applying oil discharged from the electric oil pump EOP to the stator coil 48 of the electric motor MG1.

[0026] The electronic control device 90 is configured to include a so-called microcomputer. The electronic control device 90 is supplied with various signals (for example, the coil temperature Tc of the stator coil 48, the atmospheric pressure Pa, the battery charge level SOC, etc.) based on detection values ​​from an electric motor temperature sensor 92, an atmospheric pressure sensor 94, a battery charge level sensor 96, etc., which are provided on the vehicle 10. On the other hand, the electronic control device 90 outputs a command signal Seap for the electric oil pump EOP to the electric motor 64 of the electric oil pump EOP. The command signal Seap instructing the electric oil pump EOP to be driven drives the electric motor 64 (electric oil pump EOP), and oil is discharged toward the coil end 72. The electronic control device 90 corresponds to the "control device" of the present invention.

[0027] The electronic control device 90 functionally includes a pump control section 100 that controls the driving of the electric oil pump EOP.

[0028] The drive control of the electric oil pump EOP is performed, for example, based on the calculation result of the effective withstand voltage value Vra, which is the difference between the basic insulation withstand voltage value Vbase of the stator coil 48 and the stress value Vstr in the actual operating environment, as shown in the following equation (1). Effective breakdown voltage Vra = Basic insulation breakdown voltage Vbase - Stress value Vstr (1) When the effective withstand pressure value Vra is equal to or greater than 0, the electric oil pump EOP is stopped, and when the effective withstand pressure value Vra is negative, the electric oil pump EOP is driven.

[0029] Conventionally, the effective withstand voltage value Vra is calculated from the coil temperature Tc and the atmospheric pressure Pa. For example, the calculation is performed by applying the coil temperature Tc and the atmospheric pressure Pa to a map that is previously set by design or experiment.

[0030] The dielectric strength voltage Vins of the stator coil 48 of the electric motor MG1 is also affected by the state of charge (SOC) of the battery, which is the power source of the electric motor MG1. The battery voltage also changes as the state of charge (SOC) of the battery changes. In the vehicle 10, the battery voltage is applied directly to the electric motor MG1, so a change in this applied voltage also changes the required dielectric strength voltage Vins of the stator coil 48. For example, when the state of charge (SOC) of the battery, i.e., the battery voltage, is low, the required dielectric strength voltage Vins also decreases, which makes it possible to reduce the frequency of cooling by oil discharge. However, in the past, the electric oil pump EOP was driven without taking this into consideration, leaving room for improvement in terms of improving fuel economy.

[0031] To address the above-mentioned issues, the pump control unit 100 of this embodiment calculates the effective withstand pressure value Vra based on three detected values: the coil temperature Tc, the atmospheric pressure Pa, and the battery charge state SOC, thereby appropriately controlling the drive of the electric oil pump EOP.

[0032] 3 is a flowchart for explaining the main control operations of the pump control section 100, which is functionally included in the electronic control device 90. This flowchart is repeatedly executed while the vehicle is running.

[0033] First, in step (hereinafter, step will be omitted) S10, the effective withstand voltage value Vra is calculated. The calculation of the effective withstand voltage value Vra is performed, for example, by applying the detected values ​​of the coil temperature Tc, the altitude (converted from atmospheric pressure Pa), and the state of charge SOC to a pre-calculated three-dimensional map VMAP, as shown in the balloon on the right side of FIG. 3. The numerical values ​​in the map VMAP indicate the effective withstand voltage value Vra, and although not shown, the map has the characteristic that the smaller the state of charge SOC, the narrower the area showing negative values.

[0034] Next, in S20, it is determined whether the effective withstand pressure value Vra is negative. If the determination in S20 is positive, the electric oil pump EOP is driven, and if the determination in S20 is negative, the electric oil pump EOP is stopped and this routine is terminated.

[0035] Moreover, the control of the drive of the electric oil pump EOP by the pump control unit 100 is similarly applied to the electric motor MG2.

[0036] As described above, according to the electronic control device 90 of this embodiment, the operation of the electric oil pump EOP is controlled based on the map VMAP that is preset based on the atmospheric pressure Pa detected by the atmospheric pressure sensor 94, the coil temperature Tc of the stator coils (48, 55) of the electric motors (MG1, MG2), and the battery charge state SOC. This allows the operation of the electric oil pump EOP to be appropriately controlled, including the battery charge state SOC, i.e., the battery voltage, so that the withstand voltage Vins of the stator coils (48, 55) of the electric motors (MG1, MG2) is ensured and the electric fuel efficiency is improved in the operation of the electric oil pump EOP.

[0037] The above describes in detail an embodiment of the present invention based on the drawings, but what has been described above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0038] 10: Vehicle 48: Stator coil (coil) 55: Stator coil (coil) 70: Cooling mechanism 90: Electronic control unit (control unit) 94: Atmospheric pressure sensor MG1: Electric motor MG2: Electric motor EOP: Electric oil pump Pa: Atmospheric pressure SOC: Battery charge amount (charge amount) Tc: Coil temperature VMAP: Map

Claims

[Claim 1] A control device for a vehicle including an electric motor, a cooling mechanism that cools the electric motor with oil discharged from an electric oil pump, and a battery that supplies and receives electric power to the electric motor, The control device controls the operation of the electric oil pump based on a map that is set in advance based on the atmospheric pressure detected by an atmospheric pressure sensor, the temperature of the coil of the electric motor, and the charge amount of the battery. A vehicle control device characterized by:

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