Motor device

Abstract

A motor device prevents electrolytic corrosion of a bearing. The motor device is mounted on a vehicle and has a stator installed in a housing and provided with a concentrated winding coil, a rotor housed in the center of the stator and provided with a permanent magnet, a bearing installed in the housing and supporting a rotating shaft of the rotor, an inverter provided between the stator and a power storage body and controlling an energization state of the concentrated winding coil, and an energization control section that outputs a control signal to the inverter and executes field weakening control that generates a magnetic flux of the concentrated winding coil in a direction to weaken a magnetic flux of the permanent magnet. The energization control section executes the field weakening control to make a potential difference between the housing and the rotating shaft, i.e., shaft voltage Va1, lower than a withstand voltage Vb1 of the bearing when a motor revolution number Nm is greater than a threshold value Nx.

Description

TECHNICAL FIELD

[0001] The present application relates to a motor device mounted on a vehicle. BACKGROUND

[0002] An electric motor such as a motor for running or a motor for power generation is provided in a vehicle such as an automobile. This electric motor has a stator housed in a housing and a rotor housed in the center of the stator. Further, a bearing that supports a rotating shaft of the rotor is installed in the housing (see Patent Documents 1 to 3).

[0003] PRIOR ART DOCUMENTS

[0004] PATENT DOCUMENTS

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-158318

[0006] Patent Document 2: Japanese Patent No. 4622593

[0007] Patent Document 3: Japanese Patent No. 5732309 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, since circumferential magnetic flux fluctuation occurs in the stator of the electric motor, a potential difference occurs between the stator and the rotor in a direction in which the magnetic flux fluctuation is canceled. Further, since the stator contacts the outer ring of the bearing via the housing, and the rotor contacts the inner ring of the bearing via the rotating shaft, a state in which a potential difference occurs between the outer ring and the inner ring of the bearing is created. Moreover, if the potential difference between the outer ring and the inner ring is greater than the insulation breakdown voltage of the lubricating oil film formed in the bearing, electrolytic corrosion in the bearing can occur. Since such electrolytic corrosion is a major cause of damage to the bearing, electrolytic corrosion in the bearing is being sought to be prevented.

[0010] An object of the present application is to prevent electrolytic corrosion in a bearing.

[0011] TECHNICAL SOLUTION

[0012] The motor device of the present application is a motor device mounted on a vehicle, the motor device having: a stator installed in a housing and provided with a concentrated winding coil; a rotor housed in the center of the stator and provided with a permanent magnet; a bearing installed in the housing and supporting a rotation shaft of the rotor; an inverter provided between the stator and an electricity storage body and controlling an energization state of the concentrated winding coil; and an energization control section that outputs a control signal to the inverter, and executes a field weakening control that generates a magnetic flux of the concentrated winding coil in a direction to weaken a magnetic flux of the permanent magnet, the energization control section executing the field weakening control when a rotation speed of the rotor is greater than a threshold value, and making a potential difference between the housing and the rotation shaft lower than a withstand voltage of the bearing.

[0013] Technical Effects

[0014] According to the present application, the energization control section executes the field weakening control when the rotation speed of the rotor is greater than the threshold value, and makes the potential difference between the housing and the rotation shaft lower than the withstand voltage of the bearing. Thereby, electrolytic corrosion of the bearing can be prevented. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 is a schematic view showing a configuration example of a vehicle mounted with a motor device as one embodiment of the present application.

[0016] Figure 2 is a sectional view along a rotor shaft of a motor generator.

[0017] Figure 3 is a sectional view along Figure 2 A-A line.

[0018] Figure 4 is a flowchart showing an example of execution steps of bearing protection control 1 by a controller.

[0019] Figure 5 is a graph showing a relationship between an axle voltage and a bearing withstand voltage with respect to a motor revolution number.

[0020] Figure 6 is a graph showing a change in a magnetic flux density in a motor circumferential direction generated according to presence or absence of a field weakening control.

[0021] Figure 7 is a flowchart showing an example of execution steps of bearing protection control 2 by a controller.

[0022] Figure 8 (A) of Figure 8 (B) of is a graph showing an example of a relationship between a motor torque and a threshold value.

[0023] Figure 9is a graph showing a relationship between an axle voltage and a bearing withstand voltage with respect to a motor revolution number.

[0024] Figure 10 is a flowchart showing an example of execution steps of the bearing protection control 3 by the controller.

[0025] Figure 11 (A) of FIG. 6 and Figure 11 (B) of FIG. 6 is a graph showing an example of a relationship between a vehicle acceleration and a threshold value.

[0026] Figure 12 is a graph showing a relationship between an axle voltage and a bearing withstand voltage with respect to a motor revolution number.

[0027] Symbol explanation

[0028] 10: motor device 11: vehicle

[0029] 20: rotor 30: motor housing (housing)

[0030] 31: stator 32: rotor shaft (rotating shaft)

[0031] 33, 34: bearing 35: inverter

[0032] 36: battery (power storage) 41: energization control section

[0033] 52: concentrated-wound coil 54: permanent magnet

[0034] Nx: threshold value Nm: motor revolution number (rotational speed)

[0035] Va: axle voltage (potential difference) Vb: bearing withstand voltage (withstand voltage)

[0036] S: axial direction DETAILED DESCRIPTION

[0037] Hereinafter, an embodiment of the present application will be described in detail based on the drawings.

[0038] [Vehicle structure]

[0039] Figure 1 is a schematic view showing a configuration example of a vehicle 11 in which the motor device 10 as one embodiment of the present application is mounted. Note that, Figure 1 The vehicle 11 shown in FIG. 1 is a hybrid vehicle provided with an engine 12 and a motor generator 13 as a power source, but is not limited thereto, and the motor device 10 of the present embodiment can be applied even to an electric vehicle not provided with the engine 12.

[0040] As Figure 1As shown, an engine 12 and a motor generator 13 are provided in a power unit 14 mounted on a vehicle 11. Further, a continuously variable transmission 17 composed of a main pulley 15 and a secondary pulley 16 is provided in the power unit 14. The engine 12 is linked to one side of the main pulley 15 via a forward-reverse switching mechanism 18 and a torque converter 19, and a rotor 20 of the motor generator 13 is linked to the other side of the main pulley 15. Further, a wheel 23 is linked to the secondary pulley 16 via a wheel output shaft 21, a differential mechanism 22, and the like.

[0041] The motor generator 13 provided in the motor device 10 as an electric motor has a stator 31 housed in a motor case (case) 30 and the rotor 20 housed in the center of the stator 31. Further, a rotor shaft 32 as a rotation axis of the rotor 20 is rotatably supported to the motor case 30 via bearings 33, 34. Also, an inverter 35 is connected to the stator 31, and the inverter 35 is connected to a battery (power storage) 36 such as a lithium ion battery.

[0042] The inverter 35 is composed of switching elements, capacitors, and the like, and has a function of converting direct current power and alternating current power to each other. When the motor generator 13 is controlled to a power running state, direct current power is converted to alternating current power via the inverter 35, and power is supplied from the battery 36 to the motor generator 13. On the other hand, when the motor generator 13 is controlled to a regeneration state, alternating current power is converted to direct current power via the inverter 35, and power is supplied from the motor generator 13 to the battery 36.

[0043] In order to control the motor generator 13, the motor device 10 has an electronic control unit, that is, a controller 40 composed of a microcomputer or the like. Further, in order to control energization states of the concentrated winding coils 52 described later, an energization control section 41 that outputs a control signal to the inverter 35 is provided in the controller 40. Also, the controller 40 is connected to a vehicle speed sensor 42 that detects a running speed, that is, a vehicle speed of the vehicle 11, an accelerator sensor 43 that detects an operation state of an accelerator pedal, a brake sensor 44 that detects an operation state of a brake pedal, a motor rotation sensor 45 that detects a rotation speed, that is, a motor revolution number Nm of the rotor 20, and an acceleration sensor 46 that detects an acceleration in a front-rear direction of the vehicle 11, and the like.

[0044] [MOTOR GENERATOR STRUCTURE]

[0045] Next, the structure of the motor generator 13 will be described. Figure 2 is a cross-sectional view along the rotor shaft 32 of the motor generator 13, Figure 3 is a cross-sectional view along Figure 2 the A-A line of Figure 2 and Figure 3As shown, the stator 31 installed within the motor housing 30 has a generally cylindrical stator core 50 made of stacked silicon steel plates or the like, and a concentrated winding coil 52 wound around each tooth 51 of the stator core 50. Furthermore, the rotor 20 housed in the center of the stator 31 has a generally cylindrical rotor core 53 made of stacked silicon steel plates or the like, a plurality of permanent magnets 54 embedded in the rotor core 53, and a rotor shaft 32 inserted into the center of the rotor core 53.

[0046] The motor housing 30 constituting the outer casing of the electric generator 13 has a generally cylindrical housing body 60 that holds the stator 31, a generally disc-shaped end plate 61 that closes one end of the housing body 60, and a generally disc-shaped end plate 62 that closes the other end of the housing body 60. A bearing 33 that rotatably supports one end of the rotor shaft 32 is installed in an opening 61a formed in the center of one end plate 61. Furthermore, a bearing 34 that rotatably supports the other end of the rotor shaft 32 is installed in an opening 62a formed in the center of the other end plate 62.

[0047] The bearings 33 and 34 supporting the rotor shaft 32 have outer rings 33o and 34o mounted on end plates 61 and 62, inner rings 33i and 34i mounted on the rotor shaft 32, and rolling elements 33r and 34r disposed between the outer rings 33o and 34o and the inner rings 33i and 34i. It should be noted that the outer rings 33o and 34o, the inner rings 33i and 34i, and the rolling elements 33r and 34r are formed using a conductive metallic material. Furthermore, the illustrated electric generator 13 is a 4-pole, 15-slot electric generator 13, but it is not limited to this; other numbers of poles and slots may be used.

[0048] Electrolytic corrosion of bearings

[0049] Next, the electrolytic corrosion of bearings 33 and 34 will be explained. When driving the electric generator 13 by controlling the energization state of the concentrated winding coil 52, as... Figure 3 As indicated by arrow MF1, since magnetic flux is generated sequentially through adjacent teeth 51, circumferential magnetic flux fluctuations can be considered in the stator 31 as shown by arrow MF2. When such circumferential magnetic flux fluctuations occur, a potential difference Va (hereinafter referred to as shaft voltage Va) is generated between the stator 31 and the rotor 20 in the direction that cancels out the magnetic flux fluctuations. Therefore, depending on the magnitude of the shaft voltage Va, electrolytic corrosion of bearings 33 and 34 is possible.

[0050] Here, since the stator 31 is connected to the outer rings 33o and 34o via the motor housing 30, and the rotor 20 is connected to the inner rings 33i and 34i via the rotor shaft 32, therefore... Figure 2As shown in an enlarged portion thereof, an axial voltage Va is generated between the outer ring 33o, 34o and the inner ring 33i, 34i of the bearing 33, 34. Also, if the axial voltage Va between the outer ring 33o, 34o and the inner ring 33i, 34i is greater than the withstand voltage Vb of the bearing 33, 34 (hereinafter, referred to as bearing withstand voltage Vb), as shown in Figure 2 the current flows along a path C1 indicated by a single-dot chain line, and thus, the bearing 33, 34 can be subjected to electrolytic corrosion due to sparking or the like at the time of energization.

[0051] Note that the bearing withstand voltage Vb refers to an insulating breakdown voltage of the lubricating oil film F formed in the bearing 33, 34. As shown in Figure 2 As shown in an enlarged portion thereof, a lubricating oil film F functioning as an insulating film is formed between the outer ring 33o, 34o and the rolling element 33r, 34r and / or between the inner ring 33i, 34i and the rolling element 33r, 34r. That is, the condition in which the axial voltage Va is greater than the bearing withstand voltage Vb refers to a condition in which the insulating state of the bearing 33, 34 is not ensured due to damage to the lubricating oil film F, and a condition in which the bearing 33, 34 can be subjected to electrolytic corrosion due to sparking or the like at the time of energization.

[0052] [Bearing protection control 1]

[0053] As described above, if the circumferential magnetic flux fluctuation occurs in the stator 31, and the axial voltage Va is greater than the bearing withstand voltage Vb, the bearing 33, 34 can be subjected to electrolytic corrosion. Therefore, the motor device 10 of the present embodiment prevents the axial voltage Va from being greater than the bearing withstand voltage Vb by executing the bearing protection control 1 for protecting the bearing 33, 34 from electrolytic corrosion. Here, Figure 4 is a flowchart showing an example of execution steps of the bearing protection control 1 performed by the controller 40. Further, Figure 5 is a graph showing a relationship between the axial voltage Va1 and the bearing withstand voltage Vb1 with respect to the motor revolution number Nm. Also, Figure 6 is a graph showing a change in the circumferential magnetic flux density of the motor according to the presence or absence of the field weakening control. Note that Figure 5 the axial voltage Va1 shown in FIG. 8 is an example of the above-described axial voltage Va, Figure 5 the bearing withstand voltage Vb1 shown in FIG. 8 is an example of the above-described bearing withstand voltage Vb.

[0054] As shown in Figure 4As shown, in step S10, it is determined whether the motor revolution number Nm is greater than a predetermined threshold value Nx. In the case where it is determined in step S10 that the motor revolution number Nm is greater than the threshold value Nx, step Sll is reached, and field weakening control is executed on the motor generator 13. Here, the field weakening control refers to control to generate magnetic flux of the concentrated winding coil 52 provided to the stator 31 in a direction to weaken the magnetic flux of the permanent magnet 54 provided to the rotor 20. Note that in the field weakening control, the magnetic flux of the permanent magnet 54 can be weakened by circulating a negative d-axis current through the concentrated winding coil 52. Further, since the field weakening control is control to advance the current angle of the concentrated winding coil 52, it is also referred to as advance angle control.

[0055] If the field weakening control of the motor generator 13 is executed in step Sll, step S12 is reached, and it is determined whether the motor revolution number Nm is greater than the threshold value Nx. In the case where it is determined in step S12 that the motor revolution number Nm is greater than the threshold value Nx, step Sll is returned to, and the field weakening control of the motor generator 13 is continued. On the other hand, in the case where it is determined in step S12 that the motor revolution number Nm is the threshold value Nx or less, step S13 is reached, and the field weakening control of the motor generator 13 is stopped. In this way, in the bearing protection control 1, the field weakening control of the motor generator 13 is executed in a region where the motor revolution number Nm is greater than the threshold value Nx.

[0056] Here, as shown in FIG. 6, since the induced voltage rises as the motor revolution number Nm rises, the shaft voltage Vai rises. Therefore, in the example shown in FIG. 6, if the motor revolution number Nm is greater than the predetermined value Nl, the shaft voltage Vai enters the electrolytic corrosion region a where the shaft voltage Vai is greater than the bearing withstand voltage Vbl, and thus, electrolytic corrosion of the bearings 33, 34 can occur. Figure 5 Figure 5 Therefore, in the above-described bearing protection control 1, in the case where the motor revolution number Nm is greater than the threshold value Nx which is on the low-speed rotation side compared to the predetermined value Nl, the field weakening control of the motor generator 13 is executed. As shown in FIG. 6, in the case where the field weakening control is executed, the motor circumferential magnetic flux density can be lowered from "T2" to "Tl" compared to the case where the field weakening control is not executed. That is, by executing the field weakening control, the increase in the induced voltage can be suppressed by lowering the magnetic flux density, and the increase in the above-described shaft voltage Vai can be suppressed.

[0057] Therefore, in the above-described bearing protection control 1, in the case where the motor revolution number Nm is greater than the threshold value Nx which is on the low-speed rotation side compared to the predetermined value Nl, the field weakening control of the motor generator 13 is executed. As shown in FIG. 6, in the case where the field weakening control is executed, the motor circumferential magnetic flux density can be lowered from "T2" to "Tl" compared to the case where the field weakening control is not executed. That is, by executing the field weakening control, the increase in the induced voltage can be suppressed by lowering the magnetic flux density, and the increase in the above-described shaft voltage Vai can be suppressed. Figure 6

[0058] As shown in FIG. 6, in the case where the field weakening control is executed, the motor circumferential magnetic flux density can be lowered from "T2" to "Tl" compared to the case where the field weakening control is not executed. That is, by executing the field weakening control, the increase in the induced voltage can be suppressed by lowering the magnetic flux density, and the increase in the above-described shaft voltage Vai can be suppressed. Figure 5 ​​As indicated by the dotted line Xa, by performing the field weakening control when the motor revolution number Nm is larger than the threshold value Nx, it is possible to suppress an increase in the shaft voltage Va1 so as not to exceed the bearing withstand voltage Vb1. That is, it is possible to make the shaft voltage Va1 lower than the bearing withstand voltage Vb1, and it is possible to prevent electrolytic corrosion from occurring in the bearings 33, 34. Thus, it is possible to properly protect the bearings 33, 34, and it is possible to improve the durability of the motor generator 13.

[0059] [Shaft bearing protection control 2]

[0060] Next, another example of the shaft bearing protection control will be described. In the above-described shaft bearing protection control 1, the threshold value Nx that is set in advance is used as the threshold value for the comparison determination with the motor revolution number Nm, but it is not limited thereto, and the threshold value Nx can be increased or decreased based on the motor generator 13. Here, Figure 7 is a flowchart showing an example of the execution steps of the shaft bearing protection control 2 performed by the controller 40. Further, Figure 8 (A) of Figure 8 (B) of Figure 9 is a graph showing the relationship between the shaft voltage Va2 and the bearing withstand voltage Vb2 with respect to the motor revolution number Nm. It should be noted that Figure 9 the shaft voltage Va2 shown in Figure 9 the bearing withstand voltage Vb2 shown in

[0061] As shown in Figure 7 , in step S20, the threshold value Nx is set based on the output torque of the motor generator 13, that is, the motor torque. Here, as shown in Figure 8 (A), the threshold value Nx is set to decrease as the motor torque increases. It should be noted that the threshold value Nx can be continuously changed according to the motor torque as shown in Figure 8 (A), or it can be changed stepwise according to the motor torque as shown in Figure 8 (B). If the threshold value Nx is thus set based on the motor torque, as shown in Figure 7 , step S21 is entered, and it is determined whether the motor revolution number Nm is larger than the threshold value Nx. In step S21, in the case where it is determined that the motor revolution number Nm is larger than the threshold value Nx, step S22 is entered, and the field weakening control is performed on the motor generator 13.

[0062] In step S22, if the field weakening control of the motor generator 13 is executed, step S23 is reached, the threshold value Nx is set again on the basis of the motor torque, and step S24 is reached, it is determined whether the motor revolution number Nm is below the threshold value Nx. In the case where it is determined in step S24 that the motor revolution number Nm is greater than the threshold value Nx, step S22 is returned to, and the field weakening control of the motor generator 13 is continued. On the other hand, in the case where it is determined in step S24 that the motor revolution number Nm is below the threshold value Nx, step S25 is reached, and the field weakening control of the motor generator 13 is stopped. In this way, in the bearing protection control 2, the threshold value Nx is set on the basis of the motor torque, and the field weakening control is executed in a region where the motor revolution number Nm is greater than the threshold value Nx.

[0063] Here, as shown in the characteristic curves La1 to La3, the shaft voltage Va2 rises as the motor revolution number Nm rises. In addition, even with the same motor revolution number Nm, in the case where the motor torque is increased by increasing the current, the shaft voltage rises as the induced voltage rises, whereas in the case where the motor torque is decreased by decreasing the current, the shaft voltage falls as the induced voltage falls. That is, from the condition where the shaft voltage Va2 is increased and decreased along the characteristic curve La1, in the case where the motor torque is increased, the shaft voltage Va2 is increased and decreased along the characteristic curve La2, whereas in the case where the motor torque is decreased, the shaft voltage Va2 is increased and decreased along the characteristic curve La3. Figure 9 Therefore, in the example shown in FIG. 8, in the case where the condition is such that the shaft voltage Va2 is increased and decreased along the characteristic curve La1, if the motor revolution number Nm is greater than a predetermined value Na1, the shaft voltage Va2 enters the electrolytic corrosion occurrence region a where the shaft voltage Va2 is greater than the bearing withstand voltage Vb2, and thus it is likely that the electrolytic corrosion occurs in the bearings 33, 34. In addition, in the case where the condition is such that the shaft voltage Va2 is increased and decreased along the characteristic curve La2, if the motor revolution number Nm is greater than a predetermined value Na2 which is located on the low-speed rotation side compared to "Na1", the shaft voltage Va2 enters the electrolytic corrosion occurrence region a where the shaft voltage Va2 is greater than the bearing withstand voltage Vb2, and thus it is likely that the electrolytic corrosion occurs in the bearings 33, 34. That is, in the case where the motor torque is increased, compared to the case where the motor torque is decreased, the electrolytic corrosion occurrence region a is entered at a lower motor revolution number Nm.

[0064] Figure 9 Therefore, in the bearing protection control 2 described above, the threshold value Nx is set to fall as the motor torque increases. That is, in the case where the motor torque is increased, as shown by the arrow β in FIG. 9, the threshold value Nx is set to fall from "Nx1" to "Nx2". Thereby, in the case where the motor torque is increased, the field weakening control can be executed as early as possible, and thus, as shown in FIG. 10, the shaft voltage Va2 can be prevented from entering the electrolytic corrosion occurrence region a.

[0065] Therefore, in the bearing protection control 2 described above, the threshold value Nx is set to fall as the motor torque increases. That is, in the case where the motor torque is increased, as shown by the arrow β in FIG. 9, the threshold value Nx is set to fall from "Nx1" to "Nx2". Thereby, in the case where the motor torque is increased, the field weakening control can be executed as early as possible, and thus, as shown in FIG. 10, the shaft voltage Va2 can be prevented from entering the electrolytic corrosion occurrence region a. Figure 9 Figure 9 ​​As shown by a dotted line Xb, the increase in the shaft voltage Va2 can be suppressed so as not to exceed the bearing withstand voltage Vb2. That is, the shaft voltage Va2 can be made lower than the bearing withstand voltage Vb2, and electrolytic corrosion in the bearings 33, 34 can be prevented. Thus, the bearings 33, 34 can be properly protected, and the durability of the motor generator 13 can be improved.

[0066] It should be noted that, as the motor torque used to set the threshold value Nx, a target torque of the motor generator 13 set based on the vehicle speed and / or the accelerator pedal opening degree, or an output torque of the motor generator 13 estimated from the current flowing through the concentrated-winding coil 52 can be used.

[0067] [Bearing protection control 3]

[0068] Next, another example of the bearing protection control will be described. In the above-described bearing protection control 1, the threshold value Nx set in advance is used as the threshold value for the comparison determination with the motor revolution number Nm, but it is not limited thereto, and the threshold value Nx can be increased or decreased based on the vehicle acceleration. Here, Figure 10 is a flowchart showing an example of the execution steps of the bearing protection control 3 performed by the controller 40. Further, Figure 11 (A) and Figure 11 (B) of FIG. 10 are graphs showing an example of the relationship between the vehicle acceleration and the threshold value Nx. Also, Figure 12 is a graph showing the relationship between the shaft voltage Va3 and the bearing withstand voltage Vb3 with respect to the motor revolution number Nm. It should be noted that, Figure 12 the shaft voltage Va3 shown in FIG. 11 is an example of the above-described shaft voltage Va, Figure 12 the bearing withstand voltage Vb3 shown in FIG. 12 is an example of the above-described bearing withstand voltage Vb.

[0069] As shown in Figure 10 , in step S30, the threshold value Nx is set based on the vehicle acceleration acting at the time of vehicle acceleration. Here, as shown in Figure 11 (A), the threshold value Nx is set to decrease as the vehicle acceleration increases. It should be noted that the threshold value Nx can be continuously changed according to the vehicle acceleration as shown in Figure 11 (A), or can be changed stepwise according to the vehicle acceleration as shown in Figure 11 (B). If the threshold value Nx is thus set based on the vehicle acceleration, as shown in Figure 10 , step S31 is entered, and it is determined whether the motor revolution number Nm is greater than the threshold value Nx. In a case where it is determined in step S31 that the motor revolution number Nm is greater than the threshold value Nx, step S32 is entered, and the field weakening control is executed on the motor generator 13.

[0070] In step S32, if the field weakening control of the motor generator 13 is executed, step S33 is reached, the threshold value Nx is set again on the basis of the vehicle acceleration, and step S34 is reached, it is determined whether the motor revolution number Nm is below the threshold value Nx. In the case where it is determined in step S34 that the motor revolution number Nm is greater than the threshold value Nx, the process returns to step S32, and the field weakening control of the motor generator 13 is continued. On the other hand, in the case where it is determined in step S34 that the motor revolution number Nm is below the threshold value Nx, step S35 is reached, and the field weakening control of the motor generator 13 is stopped. In this way, in the bearing protection control 3, the threshold value Nx is set on the basis of the vehicle acceleration, and the field weakening control is executed in a region where the motor revolution number Nm is greater than the threshold value Nx.

[0071] Here, as shown in FIG. 6, since the induced voltage rises as the motor revolution number Nm rises, the shaft voltage Va3 rises. In addition, as shown in the characteristic curves Lbl to Lb3 in FIG. 6, even if the motor revolution number Nm is the same, in the case where the vehicle acceleration increases, the lubricating oil film F becomes thin and the bearing pressure resistance Vb3 drops, and on the other hand, in the case where the vehicle acceleration decreases, the lubricating oil film F becomes thick and the bearing pressure resistance Vb3 rises. That is, from the condition where the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lbl, in the case where the vehicle acceleration increases, the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lb2, and on the other hand, in the case where the vehicle acceleration decreases, the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lb3. Figure 12 Figure 12 Here, as shown in FIG. 6, since the induced voltage rises as the motor revolution number Nm rises, the shaft voltage Va3 rises. In addition, as shown in the characteristic curves Lbl to Lb3 in FIG. 6, even if the motor revolution number Nm is the same, in the case where the vehicle acceleration increases, the lubricating oil film F becomes thin and the bearing pressure resistance Vb3 drops, and on the other hand, in the case where the vehicle acceleration decreases, the lubricating oil film F becomes thick and the bearing pressure resistance Vb3 rises. That is, from the condition where the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lbl, in the case where the vehicle acceleration increases, the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lb2, and on the other hand, in the case where the vehicle acceleration decreases, the bearing pressure resistance Vb3 is increased and decreased along the characteristic curve Lb3.

[0072] As shown in FIG. 5, the motor generator 13 is assembled in the powertrain 14 in a longitudinal arrangement. That is, the axial direction S of the rotor shaft 32 of the motor generator 13 is arranged along the front-rear direction of the vehicle 11. Therefore, in the case where the vehicle acceleration increases, as shown by the arrow Axl in FIG. 5, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle rearward direction increases. This axial load is the cause of the relative movement of the outer ring 33o, 34o and the inner ring 33i, 34i of the bearings 33, 34 in the axial direction, and is the cause of the partial reduction of the clearances of the outer ring 33o, 34o and the rolling elements 33r, 34r and the clearances of the inner ring 33i, 34i and the rolling elements 33r, 34r. That is, since the lubricating oil film F in the bearings 33, 34 becomes thin in accordance with the axial load, it is considered that the bearing pressure resistance Vb drops in the case where the vehicle acceleration increases. Figure 1 Figure 2 Therefore, in the case where the vehicle acceleration increases, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle rearward direction increases, and the lubricating oil film F in the bearings 33, 34 becomes thin. As a result, the bearing pressure resistance Vb drops. In the case where the vehicle acceleration decreases, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle rearward direction decreases, and the lubricating oil film F in the bearings 33, 34 becomes thick. As a result, the bearing pressure resistance Vb rises.

[0073] Therefore, in the case where the vehicle acceleration increases, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle rearward direction increases, and the lubricating oil film F in the bearings 33, 34 becomes thin. As a result, the bearing pressure resistance Vb drops. In the case where the vehicle acceleration decreases, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle rearward direction decreases, and the lubricating oil film F in the bearings 33, 34 becomes thick. As a result, the bearing pressure resistance Vb rises. Figure 12 ​​In the example shown, when the bearing withstand pressure Vb3 increases or decreases along the characteristic curve Lb1, if the motor speed Nm is greater than the predetermined value Nb1, the bearing voltage Va3 exceeds the electrolytic corrosion region α, potentially leading to electrolytic corrosion of bearings 33 and 34. Furthermore, when the bearing withstand pressure Vb3 increases or decreases along the characteristic curve Lb2, if the motor speed Nm is greater than the predetermined value Nb2 (which is on the lower rotational speed side compared to Nb1), the bearing voltage Va3 exceeds the electrolytic corrosion region α, potentially leading to electrolytic corrosion of bearings 33 and 34. In other words, when vehicle acceleration increases, the lower motor speed Nm will cause the bearing to enter the electrolytic corrosion region α compared to when vehicle acceleration decreases.

[0074] Therefore, in the bearing protection control 3 described above, the threshold Nx is set to decrease as the vehicle acceleration increases. That is, when the vehicle acceleration increases, such as... Figure 12 As indicated by the middle arrow γ, the threshold Nx is set to decrease from "Nx3" to "Nx4". Therefore, as vehicle acceleration increases, weak excitation control can be executed earlier, thus... Figure 12 As shown by the dashed lines Xc and Xd, the increase in shaft voltage Va3 can be suppressed so that it does not exceed the bearing withstand voltage Vb3. That is, the shaft voltage Va3 can be kept lower than the bearing withstand voltage Vb3, and electrolytic corrosion in bearings 33 and 34 can be prevented. Thus, bearings 33 and 34 can be properly protected, and the durability of the electric generator 13 can be improved.

[0075] In the above explanation, the threshold Nx for comparison with the motor speed Nm is set based on the vehicle acceleration during vehicle acceleration, i.e., the vehicle acceleration acting towards the rear of the vehicle, but it is not limited to this. For example, the threshold Nx for comparison with the motor speed Nm can also be set based on the vehicle deceleration during vehicle deceleration, i.e., the vehicle acceleration acting towards the front of the vehicle in the negative direction. In this case, the threshold Nx is set to decrease as the vehicle deceleration increases. It should be noted that even when the threshold Nx is set based on vehicle deceleration, it is possible to... Figure 11 As shown in (A), the threshold Nx changes continuously according to the vehicle deceleration, and can also be as follows: Figure 11 As shown in (B), the threshold Nx changes stepwise according to the vehicle deceleration.

[0076] In this way, by causing the threshold Nx to decrease with increasing vehicle deceleration, weak excitation control can be executed earlier when vehicle deceleration increases. Therefore, electrolytic corrosion in bearings 33 and 34 can be prevented in the same way as the bearing protection control 3 described above, and bearings 33 and 34 can be appropriately protected. It should be noted that when vehicle deceleration increases, if...Figure 2 As indicated by the middle arrow Ax2, the axial load acting on the rotor 20 and the rotor shaft 32 in the vehicle frontward direction increases. This axial load is a cause of locally reducing the clearances between the outer rings 33o, 34o and the rolling bodies 33r, 34r and the clearances between the inner rings 33i, 34i and the rolling bodies 33r, 34r, as in the case of the vehicle acceleration. Note that, as the vehicle acceleration and / or the vehicle deceleration for setting the threshold value Nx, an acceleration detected by the acceleration sensor 46 can be used, or an acceleration and / or a deceleration calculated in accordance with the vehicle speed can be used.

[0077] The present application is not limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof. In the examples of the bearing protection control 2, 3, the threshold value Nx is set based on one of the motor torque, the vehicle acceleration, and the vehicle deceleration, but is not limited thereto, and the threshold value Nx can be set based on at least two of the motor torque, the vehicle acceleration, and the vehicle deceleration. For example, the threshold value Nx can be set based on the motor torque and the vehicle acceleration, or the threshold value Nx can be set based on the motor torque and the vehicle deceleration. Further, the threshold value Nx can be set based on the vehicle acceleration and the vehicle deceleration, or the threshold value Nx can be set based on the motor torque, the vehicle acceleration, and the vehicle deceleration.

[0078] Further, in the above description, the motor generator 13 is assembled to the power unit 14 in a longitudinal placement manner, but is not limited thereto, and the motor generator can be assembled to the power unit in a transverse placement manner. Thus, even in the case where the rotor shaft of the motor generator is arranged in the vehicle width direction, since the axial load is input to the rotor shaft 32 at the time of vehicle acceleration and / or vehicle deceleration when the helical gear or the like is provided on the rotor shaft 32, the above-described bearing protection control 3 or the like can be effectively applied. Note that, as the power unit 14 mounted on the vehicle 11, not only the power unit exemplified above but also other forms of power units can be used. Figure 1 The exemplified power unit can be other forms of power units.

Claims

1. A motor device, characterized in that, Mounted in a vehicle, the motor assembly has: The stator is installed inside the housing and has a centrally wound coil; The rotor is housed in the center of the stator and has permanent magnets; A bearing, mounted in the housing, supports the rotating shaft of the rotor; An inverter, disposed between the stator and the energy storage element, controls the energizing state of the centrally wound coil; and The power-on control unit outputs a control signal to the inverter to execute weak excitation control. This weak excitation control generates magnetic flux in the concentrated winding coil in a direction that reduces the magnetic flux of the permanent magnet. When the rotor's rotational speed exceeds a threshold value relative to a predetermined value and is on the low-speed rotation side, the energizing control unit performs weak excitation control by flowing a negative d-axis current through the concentrated winding coil. This reduces the circumferential magnetic flux density of the motor device, suppressing the increase in the shaft voltage of the rotating shaft, thereby causing the potential difference between the housing and the rotating shaft to be lower than the bearing's withstand pressure. The predetermined value is the value at which the motor enters the electrolytic corrosion zone if the rotational speed of the motor device is greater than the predetermined value.

2. The motor device according to claim 1, characterized in that, The threshold decreases as the motor torque increases.

3. The motor device according to claim 1, characterized in that, The threshold decreases as vehicle acceleration increases.

4. The motor device according to claim 2, characterized in that, The threshold decreases as vehicle acceleration increases.

5. The motor device according to any one of claims 1 to 4, characterized in that, The threshold decreases as the vehicle deceleration increases.

6. The motor device according to any one of claims 1 to 4, characterized in that, The axis of the rotating shaft is in the front-rear direction of the vehicle.

7. The motor device according to claim 5, characterized in that, The axis of the rotating shaft is in the front-rear direction of the vehicle.

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