Control device for a vehicle

Abstract

The present application provides a vehicle in which a driver can be informed that a vehicle using oil having a low electric insulation performance. The electric insulation performance of the oil used is judged by an electric insulation performance judging section (84), and the driver is informed of the result of the judgment of the electric insulation performance of the oil used by an informing section (86). As a result, the driver can ascertain whether the electric insulation performance of the oil used is appropriate, and can take appropriate measures corresponding to the electric insulation performance of the oil.

Description

Technical Field

[0001] The present invention relates to a vehicle having at least an electric motor as a power source for driving. Background Technology

[0002] In vehicles such as electric vehicles and hybrid vehicles, which have at least an electric motor as a power source for driving, the oil used for cooling the electric motor and lubricating the power transmission device that transmits the power of the electric motor to the drive wheels requires appropriate electrical insulation properties. For example, an oil with excellent electrical insulation properties, as described in Patent Document 1, is used.

[0003] Prior art literature

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-194002

[0006] Furthermore, when using oil with low electrical insulation properties in a vehicle, a portion of the current used for driving the vehicle may leak into the oil, causing a decrease in the vehicle's driving performance. In such cases, it is preferable to inform the driver that an oil with low electrical insulation properties has been used. Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The present invention was made against the background of the above situation, and its object is to provide a vehicle in which the driver is informed that oil with low electrical insulation properties is used in a vehicle that has at least an electric motor as a power source.

[0009] Methods for solving problems

[0010] The subject of the first invention is (a) a vehicle having an electric motor that functions as a power source for driving and a power transmission device for transmitting power from the electric motor to drive wheels, characterized in that the vehicle has: (b) an electrical insulation performance determination unit that determines the electrical insulation performance of oil supplied to the electric motor and the power transmission device for lubrication; and (c) a notification unit that informs the driver of the determination result of the electrical insulation performance of the oil determined by the electrical insulation performance determination unit.

[0011] Based on the first invention, the main feature of the second invention is that (a) the vehicle has an engine that functions as a power source different from the electric motor, and (b) in a driving state where the power of the engine is distributed to the electric motor and a predetermined rotating member mechanically connected to the drive wheel, if the torque ratio calculated by dividing the sum of the estimated torque of the electric motor and the estimated torque of the predetermined rotating member by the estimated torque of the engine is greater than a first threshold of 1.0 or higher, the electrical insulation performance determination unit determines that the oil has low electrical insulation performance.

[0012] Based on the first invention, the main feature of the third invention is that the electrical insulation performance determination unit determines the electrical insulation performance of the oil based on the relationship between the estimated torque of the motor calculated based on the current applied to the motor and the output torque of the motor.

[0013] Based on the third invention, the main feature of the fourth invention is that when the torque ratio calculated by dividing the estimated torque of the motor (calculated based on the current applied to the motor) by the output torque of the motor is greater than or equal to a first threshold greater than 1.0, the electrical insulation performance determination unit determines that the oil has low electrical insulation performance.

[0014] Based on the second or fourth invention, the main feature of the fifth invention is that, when the torque ratio is above the first threshold, the notification unit informs the driver that oil with low electrical insulation properties has been used.

[0015] Based on the fifth invention, the main feature of the sixth invention is that the vehicle is configured to reduce the applied current to the electric motor when the torque ratio is greater than or equal to a second threshold that is greater than the first threshold.

[0016] Invention Effects

[0017] According to the present invention, since the electrical insulation performance is determined by the electrical insulation performance determination unit and the determination result of the electrical insulation performance of the oil is communicated by the notification unit, the driver can determine whether the electrical insulation performance of the oil is appropriate. Attached Figure Description

[0018] Figure 1 This is a schematic diagram illustrating the general structure of a hybrid vehicle to which the present invention is applied, and a functional block diagram illustrating the control system for controlling the vehicle.

[0019] Figure 2 It is used for explanation Figure 1 A flowchart of the main parts of the control operation of the electronic control device.

[0020] Figure 3 This is a diagram illustrating the schematic structure of a vehicle corresponding to another embodiment of the present invention, and also a diagram illustrating the control functions and main parts of the control system used for various controls in the vehicle.

[0021] Figure 4 This is a diagram illustrating the schematic structure of a vehicle corresponding to another embodiment of the present invention, and also a diagram illustrating the control functions and main parts of the control system used for various controls in the vehicle.

[0022] Explanation of reference numerals in the attached figures

[0023] 8, 100, 200: Vehicles

[0024] 10, 104, 204: Power transmission devices

[0025] 12: Engine

[0026] 14: Drive gear (specified rotating component)

[0027] 34: Lubrication Required Department

[0028] 36, 102, 202: Drive wheels

[0029] 84, 156, 256: Electrical Insulation Performance Judgment Section

[0030] 86, 158, 258: Notification Department

[0031] MG: Electric motor

[0032] MG1: First electric motor (electric motor)

[0033] MG2: Second electric motor (electric motor)

[0034] RT: Torque Ratio

[0035] K1: First threshold

[0036] K2: Second threshold. Detailed Implementation

[0037] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the following embodiments, the drawings are appropriately simplified or modified, and the dimensions and shapes of the parts are not necessarily depicted accurately.

[0038] Example 1

[0039] Figure 1This is a schematic diagram illustrating the general structure of a hybrid vehicle 8 (hereinafter referred to as vehicle 8) to which the present invention is applied, and a functional block diagram illustrating the control system for controlling vehicle 8. Vehicle 8 includes an engine 12 and a second electric motor MG2 as power sources for driving, and a power transmission device 10 for transmitting power from the engine 12 and the second electric motor MG2 to the drive wheels 36. The power transmission device 10 is configured within a housing 40 to include: a power distribution mechanism 16 for distributing power output from the engine 12 to a first electric motor MG1 and a secondary drive gear 14 (hereinafter referred to as drive gear 14); a secondary gear pair 20, consisting of drive gear 14 and a secondary driven gear 18 (hereinafter referred to as driven gear 18) meshing with drive gear 14; a second electric motor MG2, which is connected to driven gear 18 via a reduction gear 22 for power transmission; an end gear pair 28, consisting of a differential drive gear 24 and a differential driven gear 26; a differential device 30 (differential gear assembly); and a pair of left and right axles 32. The power transmission device 10 is preferably used in a transversely configured FF (front-engine, front-drive) vehicle 8. The driven gear 18 and the differential drive gear 24 are respectively mounted on the secondary axle 35 in a manner that prevents relative rotation. Furthermore, the first electric motor MG1 and the second electric motor MG2 correspond to the electric motors of the present invention.

[0040] In the power transmission device 10, the power from the engine 12 is transmitted to the driven gear 18 via the power distribution mechanism 16 and the drive gear 14, and the power from the second electric motor MG2 is transmitted to the driven gear 18 via the reduction gear 22. Furthermore, the power transmitted to the driven gear 18 is sequentially transmitted to the left and right pair of drive wheels 36 via the end gear pair 28, the differential device 30, and the left and right pair of axles 32. Thus, the power transmission device 10 is configured to transmit the power from the engine 12 and the second electric motor MG2 to the drive wheels 36.

[0041] A damping device 38 is provided between the engine 12 and the power distribution mechanism 16. The damping device 38 is configured to include a damping spring 38s and has the following function: by appropriately twisting the damping spring 38s according to the input torque, it absorbs torque fluctuations.

[0042] The power distribution mechanism 16 is composed of a known single-pinion type planetary gear device, which includes a sun gear S, a pinion P, a planetary carrier CA supporting the pinion P for rotation and revolution, and a ring gear R meshing with the sun gear S via the pinion P as a rotating element. The sun gear S is connected to the first electric motor MG1 for power transmission. The planetary carrier CA is connected to the engine 12 for power transmission. The ring gear R is connected to a pair of drive wheels 36 for power transmission via a drive gear 14, a driven gear 18, an end gear pair 28, a differential device 30, and a pair of axles 32. In addition, the drive gear 14 is connected to the second electric motor MG2 for power transmission via a pair of auxiliary gears 20 and a reduction gear 22. The ring gear R and the drive gear 14 are composed of an integrally formed compound gear. Furthermore, the compound gear on which the drive gear 14 is formed corresponds to a predetermined rotating member mechanically connected to the drive wheels of the present invention.

[0043] Since the sun gear S, planetary gear carrier CA, and ring gear R can rotate relative to each other, the power of the engine 12 is distributed to the first electric motor MG1 and the drive gear 14. The power of the engine 12 distributed to the first electric motor MG1 is used to generate electricity. The generated electricity is stored in the battery 74 via the inverter 76, or the generated electricity is used to drive the second electric motor MG2.

[0044] Therefore, the power distribution mechanism 16 is configured, for example, in a continuously variable transmission (CVT) state, functioning as an electric continuously variable transmission that continuously changes the rotation of the ring gear R connected to the drive gear 14, independent of the predetermined rotation of the engine 12. That is, the power distribution mechanism 16 functions as an electric differential (electric continuously variable transmission) that controls the differential state of the power distribution mechanism 16 by controlling the operation of a first electric motor MG1, which functions as a differential motor.

[0045] Furthermore, oil for lubricating various gears, bearings, and other lubrication-required components 34 housed within the housing 40 of the power transmission device 10 is stored in the lower part of the housing 40. Additionally, the oil stored in the lower part of the housing 40 is also used for cooling the first electric motor MG1 and the second electric motor MG2. For example, a portion of the differential driven gear 26 is immersed in oil, and by causing the differential driven gear 26 to raise the immersed oil during operation, oil is supplied to the various gears and bearings, the first electric motor MG1, and the second electric motor MG2.

[0046] In addition, unlike the supply path based on the lifting of the differential driven gear 26, it may be configured, for example, as a cooling circuit (not shown) for cooling the first motor MG1 and the second motor MG2, and oil drawn by the oil pump (not shown) is supplied to the first motor MG1 and the second motor MG2 via the cooling circuit.

[0047] Vehicle 8 is equipped with an electronic control device 80 for performing various controls such as driving control of vehicle 8. For example, the electronic control device 80 is supplied with signals such as the shift position Psh of shift lever 43 detected by gear position sensor 42, the throttle position θacc of accelerator pedal 45 detected by throttle position sensor 44, the operation of foot brake pedal 47 (brake on) detected by brake switch 46, the throttle position θth of electronic throttle detected by throttle position sensor 48, the crankshaft rotation angle Acr and engine speed Ne of engine 12 detected by crankshaft position sensor 50, the output speed Nout of drive gear 14 corresponding to vehicle speed V detected by output speed sensor 52, and the rotation angle θmg1 (electric angle) and speed Nm of first electric motor MG1 detected by first resolver 54. The signals include g1, the rotation angle θmg2 (electric angle) and rotation speed Nmg2 of the second motor MG2 detected by the second resolver 56, the battery temperature THbat, battery charging and discharging current Ibat, and battery voltage Vbat of the battery 74 detected by the battery sensor 58, the applied current Img1 of the first motor MG1 detected by the first current sensor 60, the applied current Img2 of the second motor MG2 detected by the second current sensor 62, the rotation speed Nr of each wheel detected by the wheel speed sensor 64, the oil temperature Toil of the oil sealed in the housing 40 detected by the oil temperature sensor 66, the operating status of the engine 12 (intake air quantity Qair, intake air temperature Tair, fuel injection quantity M, ignition timing Tig, etc.) detected by the engine status detection sensor 68, and the front and rear acceleration G detected by the acceleration sensor 70.

[0048] In addition, for example, engine control command signal Se for output control of engine 12 is output from electronic control device 80, and motor control command signal Smg for drive control of first motor MG1 and second motor MG2 is output to inverter 76.

[0049] The electronic control unit 80 functionally includes a hybrid power control unit 82, which serves as a hybrid power control component for performing hybrid power control of the vehicle 8. The hybrid power control unit 82 selectively activates, for example, a motor driving mode, an engine driving mode (normal driving mode), and an auxiliary driving mode, depending on the vehicle's driving state. In the motor driving mode, the engine 12 is stopped, and the vehicle 8 is driven solely by the second electric motor MG2 as a power source. In the engine driving mode, the generator power from the first electric motor MG1 is used to generate a reaction force relative to the power of the engine 12, thereby transmitting the direct torque of the engine to the drive gear 14. The generator power from the first electric motor MG1 drives the second electric motor MG2, transmitting torque to the driven gear 18 for driving. In the auxiliary driving mode, the second electric motor MG2, which utilizes power from the battery 74, is further used to drive the vehicle, as in the engine driving mode. In addition, the hybrid power control unit 82 can, for example, enable the engine 12 to operate in a more efficient operating range, and on the other hand, can optimize the distribution of driving force between the engine 12 and the second electric motor MG2, and the reaction force generated by the electricity generated by the first electric motor MG1, and can control the gear ratio γ0 (engine speed Ne / output speed Nout) of the power transmission device 10.

[0050] Furthermore, in the power transmission device 10, a portion of the stator coils constituting the first electric motor MG1 and the second electric motor MG2 (hereinafter referred to as each electric motor MG) are immersed in oil accumulated within the housing 40. Therefore, if the electrical insulation performance of the accumulated oil is low, the leakage current from the stator coils may increase. In this case, due to the generation of electrical short circuits and sparks, the oil may overheat abnormally, leading to device malfunction. Additionally, the decrease in the output of the electric motor MG may also lead to a decrease in vehicle driving performance and driving range. In contrast, the electronic control device 80 functionally includes an electrical insulation performance judgment unit 84, which judges the electrical insulation performance of the oil supplied to the electric motor MG and the lubrication requirement unit 34 during vehicle operation. Moreover, the electronic control device 80 functionally includes an information unit 86, which informs the driver of the judgment result of the electrical insulation performance determined by the electrical insulation performance judgment unit 84.

[0051] The electrical insulation performance of oil can be judged by the relationship between the estimated torques of each motor MG (Img1, Img2), calculated based on the applied currents Img (Img1, Img2), and the output torques of each motor MG (Tmg1, Tmg2). When the oil has good electrical insulation performance, the estimated torques Tmgest (Tmg1, Tmg2) of each motor MG, calculated based on the applied currents Img and the speeds Nmg (Nmg1, Nmg2), are equal to or approximately equal to the actual output torques Tmg of the motor MG. Therefore, when the value calculated by dividing the estimated torque Tmgest by the respective MG torque Tmg is defined as the torque ratio RT (=Tmgest / Tmg), the torque ratio RT is 1.0 or approximately 1.0 when the oil has good electrical insulation performance. On the other hand, when the electrical insulation of the oil is low, the leakage of current increases, and therefore, the actual output torque of the motor MG, i.e., the torque Tmg of each MG, becomes smaller relative to the estimated torque Tmgest of each MG based on each applied current Img. As a result, the torque ratio RT (=Tmgest / Tmg) is greater than 1.0. Furthermore, the lower the electrical insulation performance of the oil, the larger the value of each torque ratio RT. Therefore, it is possible to calculate each torque ratio RT and determine whether oil with low electrical insulation performance has been used based on whether each torque ratio RT is greater than or equal to a predetermined first threshold K1 greater than 1.0. Specifically, if each torque ratio RT is less than the first threshold K1, it is determined that the electrical insulation performance is appropriate; if each torque ratio RT is greater than or equal to the first threshold K1, it is determined that oil with low electrical insulation performance has been used. The first threshold K1 is determined experimentally or by design in advance and is set as a threshold within which the electrical insulation performance of the oil is within an acceptable range.

[0052] Each estimated MG torque Tmgest of each motor MG can be calculated based on each applied current Img to each motor MG and each MG speed Nmg of each motor MG. Each applied current Img to each motor MG can be detected by the first current sensor 60 and the second current sensor 62. The MG speed Nmg of each motor MG can be detected by the first resolver 54 and the second resolver 56, respectively. Furthermore, by providing torque sensors to detect the MG torque Tmg of each motor MG, the output torque of each motor MG, i.e., each MG torque Tmg, can be detected. Therefore, by providing torque sensors to detect the MG torque Tmg of each motor MG for each motor MG, each torque ratio RT can be calculated, and the electrical insulation performance of the oil can be determined based on the calculated torque ratio RT. However, if torque sensors are provided for each motor MG, the number of components increases. The following describes a method for determining the electrical insulation performance of oil without using torque sensors.

[0053] In vehicle 8, since it has a power distribution mechanism 16 that distributes the power of engine 12 to the first electric motor MG1 and the drive wheel 36, the driving state sometimes becomes such that the following equation (1) holds. In equation (1), Te represents the engine torque, Tmg1 represents the output torque of the first electric motor MG1 (i.e., MG1 torque Tmg1), and Td represents the drive torque (hereinafter referred to as drive torque Td) output from the drive gear 14 integrally formed with the gear ring R constituting the power distribution mechanism 16. Furthermore, the drive torque Td of the drive gear 14 is the same value as the torque output from the gear ring R.

[0054] Te=Tmg1+Td…(1)

[0055] Here, equation (1) holds true in the following engine driving mode, in which the reaction force of the power relative to the engine 12 is borne by the power generated by the first electric motor MG1, thereby transmitting the direct torque of the engine 12 to the drive gear 14, and the second electric motor MG2 is driven by the power generated by the first electric motor MG1, transmitting the torque to the driven gear 18 for driving. When judging the electrical insulation performance of the oil, firstly, the electrical insulation performance judgment unit 84 determines whether the driving conditions for equation (1) to hold true are met. For example, if all the conditions are met—being in the engine driving state, the rotational speed Nmg1 of the first electric motor MG1 being forward (i.e., in the regeneration state), and being in a driving state where no power is being transmitted or received from the battery 74—the electrical insulation performance judgment unit 84 determines that the driving conditions for equation (1) to hold true are met.

[0056] When the driving conditions under which the relationship in equation (1) holds are met, the electrical insulation performance judgment unit 84 begins to judge the control of the electrical insulation performance of the oil. First, it calculates the torque ratio RT based on the following equation (2). In equation (2), Teest represents the estimated value of the engine torque Te (hereinafter referred to as the estimated engine torque Teest), Tmg1est represents the estimated value of the MG1 torque Tmg1 of the first electric motor MG1 (hereinafter referred to as the estimated MG1 torque Tmg1est), and Tdest represents the estimated value of the drive torque Td output from the drive gear 14 (hereinafter referred to as the estimated drive torque Tdest). As can be seen from equation (2), the torque ratio RT represents the value obtained by dividing the sum of the estimated values ​​of the MG1 torque Tmg1 distributed by the power distribution mechanism 16 and the drive torque Td by the estimated value of the engine torque Te. Furthermore, the estimated drive torque Tdest corresponds to the estimated torque of the rotating member specified in this invention.

[0057] RT=(Tmg1est+Tdest) / Teest…(2)

[0058] In the absence of current leakage from each motor MG to the oil, the MG torque Tmg of each motor MG does not decrease relative to each applied current Img, and therefore the torque ratio RT becomes 1.0. On the other hand, when using oil with lower electrical insulation properties, the leakage of current from the motor MG increases. In this case, when the applied current Img of each motor MG increases, the estimated MG torque Tmgest calculated based on each applied current Img increases, but the actual MG torque Tmg of each motor MG does not increase with the current leakage. In addition, under the driving condition where equation (1) holds, the estimated engine torque Teest does not increase. As a result, when using oil with lower electrical insulation properties, the sum of the estimated MG1 torque Tmg1est and the estimated drive torque Tdest is greater than the estimated engine torque Teest, and the torque ratio RT calculated based on equation (2) is greater than 1.0.

[0059] The estimated MG1 torque Tmg1est in equation (2) is calculated by applying the applied current Img1 detected by the first current sensor 60 and the MG1 speed Nmg1 detected by the first analyzer 54 to a pre-set relational mapping or formula. The estimated engine torque Teest is calculated by applying the engine speed Ne and various states (intake air quantity Qair, intake air temperature Tair, fuel injection quantity M, ignition timing Tig, etc.) detected by the engine state detection sensor 68 to a pre-defined relational mapping or formula.

[0060] The estimated driving torque Tdest of the drive gear 14 in equation (2) is calculated based on equation (3). Here, Tdiffest corresponds to the estimated torque of the differential driven gear 26 constituting the final gear pair 28 (hereinafter referred to as the estimated differential shaft torque Tdiffest), γ1 corresponds to the mechanically defined gear ratio between the drive gear 4 and the differential driven gear 26 (hereinafter referred to as the first gear ratio γ1), Tmg2est corresponds to the estimated value of the MG2 torque of the second motor MG2 (hereinafter referred to as the estimated MG2 torque Tmg2est), and γ2 corresponds to the mechanically defined gear ratio between the second motor MG2 and the drive gear 14 (hereinafter referred to as the second gear ratio γ2). The first gear ratio γ1 is the same as the ratio of the rotational speed Nd of the drive gear 14 to the rotational speed Ndiff of the differential driven gear 26 (=Nd / Ndiff). In addition, the second gear ratio γ2 is the same as the ratio of the rotational speed Nd of the drive gear 14 to the rotational speed Nmg2 of the second motor MG2 (=Nd / Nmg2). Furthermore, when calculating the estimated drive torque Tdest, other factors such as oil temperature (Toil) can be considered to further improve the estimation accuracy.

[0061] Tdest=Tdiffest / γ1-Tmg2est / γ2…(3)

[0062] For example, the estimated differential shaft torque Tdiffest is calculated by applying the forward and backward acceleration G detected by the acceleration sensor 70 to a predefined relational mapping or formula. Additionally, the estimated MG2 torque Tmg2est is calculated by applying the applied current Img2 detected by the second current sensor 62 and the MG2 rotational speed Nmg2 detected by the second resolver 56 to a predefined relational mapping or formula.

[0063] The electrical insulation performance determination unit 84 calculates the torque ratio RT according to equations (2) and (3), and determines the electrical insulation performance of the oil based on the calculated torque ratio RT. When the electrical insulation performance of the oil is low, the sum of the estimated MG1 torque Tmg1est and the estimated drive torque Tdest increases relative to the estimated engine torque Teest. Therefore, when the electrical insulation performance of the oil is low, the torque ratio RT becomes larger than 1.0, and the lower the electrical insulation performance of the oil, the larger the torque ratio RT becomes. As a result, when calculating the torque ratio RT, the electrical insulation performance determination unit 84 determines whether the torque ratio RT is greater than or equal to the first threshold K1. If the torque ratio RT is greater than or equal to the first threshold K1, it is determined that oil with low electrical insulation performance was used. In this way, under the driving state where the relationship of equation (1) holds, the electrical insulation performance of the oil can be determined based on the torque ratio RT calculated according to equation (2) without the need to install a torque sensor. The first threshold K1 is experimentally or designed in advance and is set as the threshold where the electrical insulation performance of the oil is within the allowable range.

[0064] When the torque ratio RT is above the first threshold K1, the notification unit 86 informs the driver that oil with low electrical insulation properties has been used. The notification unit 86 may illuminate the warning light 88 located in the driver's seat or emit a warning sound from the sound device 90 to inform the driver that oil with low electrical insulation properties has been used. This allows the driver to understand that oil with low electrical insulation properties has been used and to take measures such as changing the oil.

[0065] Here, when the electrical insulation performance deteriorates significantly, the leakage of current into the oil increases, leading to increased electrical short circuits and sparks. Therefore, the oil may overheat abnormally, causing device malfunction. Thus, when the torque ratio RT is above the first threshold K1, the electrical insulation performance determination unit 84 further determines whether the torque ratio RT is above a second threshold K2, which is greater than the first threshold K1. The second threshold K2 is determined experimentally or by design in advance and is set as a threshold within a range permissible for normal operation despite lower electrical insulation performance. In other words, when the torque ratio RT is above the second threshold K2, the oil may overheat abnormally.

[0066] When the torque ratio RT is above the second threshold K2, the electrical insulation performance judgment unit 84 outputs a command to the hybrid power control unit 82 to reduce the applied currents Img1 and Img2 to the first motor MG1 and the second motor MG2. Upon receiving this command, the hybrid power control unit 82 outputs a motor control command signal Smg to the inverter 76 to reduce the applied currents Img1 and Img2 to the first motor MG1 and the second motor MG2. As a result, since the leakage of current from each motor MG to the oil is reduced, and electrical short circuits and sparks are reduced, abnormal heating of the oil can be prevented.

[0067] Furthermore, when the torque ratio RT is above the second threshold K2, the notification unit 86 will also use a warning light 88, a sound device 90, etc., to inform the driver that oil with low electrical insulation properties has been used. Moreover, when the torque ratio RT is above the second threshold K2, the notification unit 86 can also inform the driver that the driving performance has decreased as the applied currents Img1 and Img2 to the first motor MG1 and the second motor MG2 decrease.

[0068] Figure 2 This is a flowchart illustrating the main parts of the control operation of the electronic control device 80, and also a flowchart illustrating the control operation for determining whether the oil used in the power transmission device 10 has low electrical insulation properties during vehicle operation. For example, this flowchart is executed whenever the oil filled in the housing 40 is changed.

[0069] exist Figure 2In the process, firstly, in step S10 (steps omitted below) corresponding to the control function of the electrical insulation performance determination unit 84, it is determined whether the driving conditions for determining the electrical insulation performance of the oil are met. If the determination in S10 is negative, the routine ends. If the determination in S10 is positive, in step S20 corresponding to the control function of the electrical insulation performance determination unit 84, the control for determining the electrical insulation performance of the oil begins, and various factors such as the applied current Img and MG speed Nmg of each electric motor MG, and the engine speed Ne of the engine 12 are detected. Next, in step S30 corresponding to the control function of the electrical insulation performance determination unit 84, the estimated engine torque Teest of the engine 12 is calculated based on the engine speed Ne and the operating state of the engine 12 detected by the engine state detection sensor 68 (intake air quantity Qair, intake air temperature Tair, fuel injection quantity M, ignition timing Tig, etc.). In step S40 corresponding to the control function of the electrical insulation performance determination unit 84, the estimated MG1 torque Tmg1est and the estimated drive torque Tdest of the first electric motor MG1 are calculated. In S50, corresponding to the control function of the electrical insulation performance judgment unit 84, the estimated engine torque Teest calculated in S30 and the estimated MG1 torque Tmg1est and estimated drive torque Tdest calculated in S40 are applied to equation (2) to calculate the torque ratio RT, and it is determined whether the torque ratio RT is greater than or equal to the first threshold K1. If the determination in S50 is negative, it is determined that the oil's electrical insulation performance is appropriate, and in S80, corresponding to the control function of the electrical insulation performance judgment unit 84, the control for determining the oil's electrical insulation performance ends and returns to normal control. If the determination in S50 is positive, in S60, corresponding to the control function of the electrical insulation performance judgment unit 84, it is determined whether the torque ratio RT is greater than or equal to the second threshold K2. If the determination in S60 is negative, since the torque ratio RT is greater than or equal to the first threshold K1 and less than the second threshold K2, in S90, corresponding to the control function of the notification unit 86, a warning light 88 is illuminated to inform the driver that oil with low electrical insulation performance has been used. If the determination in S60 is positive, since the torque ratio RT is above the second threshold K2, in S70 corresponding to the control function of the notification unit 86, the warning lamp 88 indicating that oil with low electrical insulation performance is used is lit, and abnormal heating of the oil is prevented. Therefore, the applied current Img of each motor MG can be reduced.

[0070] As described above, according to this embodiment, since the electrical insulation performance determination unit 84 is used to determine the electrical insulation performance of the oil used, and the notification unit 86 is used to inform the driver of the determination result of the electrical insulation performance of the oil used, the driver can grasp whether the electrical insulation performance of the oil used is appropriate.

[0071] Next, another embodiment of the present invention will be described. Furthermore, in the following description, the same reference numerals are used for parts common to the above embodiments, and descriptions are omitted.

[0072] Example 2

[0073] Figure 3 This is a diagram illustrating the schematic structure of a vehicle 100 corresponding to another embodiment of the present invention, and also a diagram illustrating the control functions and main parts of the control system used for various controls in the vehicle 100. Figure 3 In this embodiment, vehicle 100 is a hybrid vehicle equipped with an engine 12 and an electric motor MG as power sources for driving. Vehicle 100 is equipped with a power transmission device 104 that transmits power from the engine 12 and the electric motor MG to the drive wheels 102. Since the engine 12 is substantially the same as in the above embodiment, the same reference numerals are used, and its description is omitted.

[0074] The electric motor MG is connected to the battery 108 of the vehicle 100 via an inverter 106. The electric motor MG controls the inverter 106 using an electronic control device 150, thereby controlling the output torque of the electric motor MG, i.e., the MG torque Tmg.

[0075] The power transmission device 104 includes a first clutch 112, a second clutch 114, and an automatic transmission 116 within a non-rotating component, housing 110, mounted on the vehicle body. The first clutch 112 is a clutch disposed between the engine 12 and the electric motor MG in the power transmission path between the engine 12 and the drive wheel 102. The second clutch 114 is a clutch disposed between the first clutch 112 and the automatic transmission 116 in the power transmission path between the engine 12 and the drive wheel 102.

[0076] The automatic transmission 116 is disposed in the power transmission path between the second clutch 114 and the drive wheel 102. The power transmission device 104 includes a drive shaft 120 connected to the output rotating member of the automatic transmission 116, namely the transmission output shaft 118, a differential device 122 connected to the drive shaft 120, and a pair of drive shafts 124 connected to the differential device 122. In addition, the power transmission device 104 includes an engine connecting shaft 126 connecting the engine 12 to the first clutch 112, an electric motor connecting shaft 128 connecting the first clutch 112 to the second clutch 114, and a transmission input shaft 130 connecting the second clutch 114 to the automatic transmission 116.

[0077] The automatic transmission 116 is, for example, a known planetary gear type automatic transmission equipped with one or more sets of planetary gear units (not shown) and multiple engagement devices CB. The engagement devices CB are, for example, hydraulic friction engagement devices consisting of multi-plate or single-plate clutches or brakes pressed by hydraulic actuators, or band brakes pulled by hydraulic actuators. The engagement devices CB switch between engagement, release, and other control states by varying their respective torque capacities, i.e., CB torques Tcb, using regulated engagement pressure PRcb supplied from the hydraulic control circuit 132. The engagement devices CB are, for example, composed of four clutches C1 to C4 and two brakes B1 and B2. The automatic transmission 116 is configured to shift to multiple gears by changing the combination of the engaged engagement devices CB.

[0078] The first clutch 112 and the second clutch 114 are wet or dry friction engagement devices consisting of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The first clutch 112 and the second clutch 114 switch between engagement, release and other control states by controlling the working state of the hydraulic actuator using an electronic control device 150.

[0079] When the first clutch 112 is engaged, the engine 12 and the electric motor MG are connected to the power transmission path via the first clutch 112. Similarly, when the second clutch 114 is engaged, the electric motor MG and the automatic transmission 116 are connected to the power transmission path via the second clutch 114. For example, when both the first clutch 112 and the second clutch 114 are engaged, the engine 12 and the electric motor MG are connected to the drive wheel 102 via the automatic transmission 116, etc. In this case, hybrid driving using the power of the engine 12 and the electric motor MG is possible. Conversely, when the first clutch 112 is released and the second clutch 114 is engaged, the power transmission from the engine 12 is cut off, while the electric motor MG is connected to the drive wheel 102, allowing power transmission. In this case, motor-driven driving using the power of the electric motor MG is possible.

[0080] Vehicle 100 is equipped with an electric oil pump 136 driven by a pump motor 134. Additionally, vehicle 100 is equipped with a mechanical oil pump (not shown) driven by at least one of an engine 12 and an electric motor MG. Working oil discharged from the electric oil pump 136 and the mechanical oil pump is supplied to a hydraulic control circuit 132. The hydraulic control circuit 132 supplies, respectively pressure-adjusted, engagement pressure PRcb to each engagement device CB, a first hydraulic pressure PRk1 to the first clutch 112, and a second hydraulic pressure PRk2 to the second clutch 114, etc., based on the working oil discharged from at least one of the electric oil pump 136 and the mechanical oil pump.

[0081] Furthermore, various signals based on detection values ​​from various sensors equipped on the vehicle 100 are supplied to the electronic control unit 150 that performs various controls on the vehicle 100. Also, for detection values ​​detected by various sensors that are the same as those in Embodiment 1 described above, the same reference numerals are used, and their descriptions are omitted. In this embodiment, a resolver 140 for detecting the rotation angle θmg and rotational speed Nmg of the motor MG, and a current sensor 142 for detecting the applied current Img of the motor MG are provided.

[0082] The electronic control unit 150 outputs various command signals (such as engine control command signal Se for controlling the engine 12, MG control command signal Sm for controlling the electric motor MG, CB hydraulic control command signal Scb for controlling the engagement device CB, hydraulic control command signal Sk for controlling the first clutch 112 and the second clutch 114, and pump control command signal Seop for controlling the electric oil pump 136) to various devices equipped in the vehicle 100 (such as engine control unit 144, inverter 106, hydraulic control circuit 132, pump motor 134, etc.).

[0083] In order to realize various controls in the vehicle 100, the electronic control device 150 includes a hybrid power control unit 152 as a hybrid power control unit, a transmission control unit 154 as a transmission control unit, an electrical insulation performance judgment unit 156 as an electrical insulation performance detection unit, and a notification unit 158 ​​as a notification unit.

[0084] The hybrid power control unit 152 establishes, for example, a motor driving mode or an engine driving mode based on the vehicle's driving status. In the motor driving mode, the engine 12 is stopped, and the electric motor MG is used exclusively as a power source to drive the vehicle 100. In the engine driving mode, the engine 12 is driven, and the vehicle 100 is driven exclusively using the power of the engine 12.

[0085] The transmission control unit 154 determines the gear corresponding to the driving state based on, for example, the throttle opening θacc and the vehicle speed V, and outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 132 to shift to the determined gear.

[0086] During vehicle operation, when the driving conditions that allow for the determination of the oil's electrical insulation performance are met, the electrical insulation performance determination unit 156 begins to determine the control of the oil's electrical insulation performance. For example, during operation in engine driving mode where both the first clutch 112 and the second clutch 114 are engaged, in a driving state where electricity is generated by transmitting a portion of the power from the engine 12 to the electric motor MG, the electrical insulation performance determination unit 156 determines that the driving conditions that allow for the determination of the oil's electrical insulation performance are met. At this time, the driving state in which the power from the engine 12 is distributed to the electric motor MG and the transmission input shaft 130 is met, and the following equation (4) is met. Here, Tmg corresponds to the MG torque of the electric motor MG (hereinafter referred to as MG torque Tmg), and Tin corresponds to the input torque transmitted to the transmission input shaft 130 (hereinafter referred to as input torque Tin). In other words, when the control of the oil's electrical insulation performance is determined, the electrical insulation performance determination unit 156 determines whether the driving state is met as shown in equation (4).

[0087] Te=Tmg+Tin…(4)

[0088] Furthermore, when the driving conditions that allow for the determination of the electrical insulation performance of the oil are met, the electrical insulation performance determination unit 156 calculates the torque ratio RT based on the following formula (5). In formula (5), Tmgest represents the estimated value of the MG torque Tmg of the electric motor MG (hereinafter referred to as the estimated MG torque Tmgest), Tinest represents the estimated value of the input torque Tin (hereinafter referred to as the estimated input torque Tinest), and Teest represents the estimated value of the engine torque Te of the engine 12 (hereinafter referred to as the estimated engine torque Teest). Based on formula (5), the torque ratio RT is calculated by dividing the sum of the estimated MG torque Tmgest of the electric motor MG and the estimated input torque Tinest by the estimated engine torque Teest.

[0089] RT=(Tmgest+Tinest) / Teest…(5)

[0090] The estimated MG torque Tmgest in Equation (5) is calculated based on the MG speed Nmg detected by the resolver 140 and the applied current Img detected by the current sensor 142. Similarly to the above embodiment, the estimated engine torque Teest in Equation (5) is estimated based on the intake air volume Qair, intake air temperature Tair, fuel injection quantity M, ignition timing Tig, etc. The estimated input torque Tinest in Equation (5) is calculated by applying the current front-rear acceleration G and the gear ratio γat of the automatic transmission 116 to a relational mapping or formula for estimating the input torque Tin, for example, composed of the front-rear acceleration G and the gear ratio γat of the automatic transmission 116.

[0091] The electrical insulation performance judgment unit 156 calculates the torque ratio RT based on equations (4) and (5), and determines whether oil with low electrical insulation performance was used based on the torque ratio RT. When oil with high electrical insulation performance is used, since the current leakage is less, the sum of the estimated MG torque Tmgest and the estimated input torque Tinest is equal to or approximately equal to the estimated engine torque Teest. That is, the torque ratio RT becomes a value of 1.0 or around 1.0. On the other hand, when oil with low electrical insulation performance is used, since the current leakage increases, the actual MG torque Tmg decreases. On the other hand, since the estimated MG torque Tmgest is estimated based on the applied current Img, it does not change. Therefore, the more the current leakage increases, the larger the sum of the estimated MG torque Tmgest and the estimated input torque Tinest becomes. In addition, since the estimated engine torque Teest remains unchanged, when oil with low electrical insulation performance is used, the torque ratio RT is greater than 1.0. Furthermore, the lower the electrical insulation performance, the larger the torque ratio RT becomes. Therefore, it is possible to determine whether oil with low electrical insulation performance was used based on the torque ratio RT calculated by equation (5). Furthermore, the control operation of the electrical insulation performance determination unit 156 after calculating the torque ratio RT is essentially the same as that of the electrical insulation performance determination unit 84 in the above embodiment, so its description is omitted. Additionally, the control function of the notification unit 158 ​​is also essentially the same as that of the notification unit 86 in the above embodiment, so its description is omitted.

[0092] As described above, even a hybrid vehicle with a single motor MG can determine whether oil with low electrical insulation performance is used based on the control operation of the electrical insulation performance determination unit 156 and the notification unit 158, and can inform the driver if oil with low electrical insulation performance is used.

[0093] Example 3

[0094] Figure 4 This diagram illustrates a schematic structure of a vehicle 200 corresponding to another embodiment of the present invention, and also illustrates the control functions and main parts of the control system used for various controls in the vehicle 200. The vehicle 200 is an electric vehicle that uses only an electric motor MG as a power source. The vehicle 200 includes a power transmission device 204 that transmits the power of the electric motor MG to the drive wheels 202.

[0095] The power transmission device 204 includes an on / off clutch 208 and an automatic transmission 210 within a non-rotating component, housing 206, mounted on the vehicle body. The on / off clutch 208 is located between the electric motor MG and the automatic transmission 210 and is designed to selectively connect or disconnect the power transmission path between the electric motor MG and the automatic transmission 210.

[0096] The electric motor MG is connected to the battery 232 of the vehicle 200 via an inverter 230. The output torque of the electric motor MG, namely the MG torque Tmg, is controlled by the inverter 230 controlled by the electronic control device 250.

[0097] Similar to the automatic transmission 116 in the above embodiment, the automatic transmission 210 is, for example, a known planetary gear type automatic transmission having one or more sets of planetary gear assemblies (not shown) and multiple engagement devices CB. Detailed description of the automatic transmission 210 is omitted.

[0098] The power transmission device 204 includes a drive shaft 214 connected to the transmission output shaft 212 of the automatic transmission 210, a differential device 216 connected to the drive shaft 214, and a pair of drive shafts 218 connected to the differential device 216. Additionally, the power transmission device 204 includes a motor connection shaft 220 connected to the electric motor MG, a transmission input shaft 222 of the automatic transmission 210, and a transmission output shaft 212.

[0099] The on / off clutch 208 is a wet or dry friction engagement device consisting of a multi-plate or single-plate clutch pressed by a hydraulic actuator (not shown). The on / off clutch 208 switches between engagement, release, and other control states by controlling the operating state of the hydraulic actuator using an electronic control device 250.

[0100] For example, when the on / off clutch 208 is engaged, the power of the electric motor MG can be transmitted to the drive wheel 202 via the automatic transmission 210. At this time, motor driving using the power of the electric motor MG is possible. On the other hand, when the on / off clutch 208 is released, the power transmission between the electric motor MG and the drive wheel 202 is cut off.

[0101] Vehicle 200 is equipped with an electric oil pump 226 driven by a pump motor 224. Furthermore, vehicle 200 is equipped with a mechanical oil pump (not shown) driven by an electric motor MG. The working oil discharged by the electric oil pump 226 and the mechanical oil pump is supplied to a hydraulic control circuit 228. The hydraulic control circuit 228 supplies engagement pressure PRcb, adjusted based on the working oil discharged by at least one of the electric oil pump 226 and the mechanical oil pump, to each engagement device CB, and on / off hydraulic pressure PRk to the on / off clutch 208, etc.

[0102] In addition, various signals based on detection values ​​from various sensors equipped on the vehicle 200 are supplied to the electronic control unit 250 that performs various controls on the vehicle 200. Regarding the description of the various sensors, since it is basically the same as in Embodiment 2 described above, the same reference numerals are used, and their descriptions are omitted. Furthermore, in this embodiment, since the engine 12 is not present, the crankshaft position sensor 50 and the engine condition detection sensor 68 are not provided.

[0103] The electronic control unit 250 outputs various command signals to the various devices equipped in the vehicle 200 (such as inverter 230, hydraulic control circuit 228, pump motor 224, etc.). These signals include MG control command signal Sm for controlling the electric motor MG, CB hydraulic control command signal Scb for controlling the engagement device CB, hydraulic control command signal Sk for controlling the on / off clutch 208, and pump control command signal Seop for controlling the electric oil pump 226.

[0104] In order to realize various controls in the vehicle 200, the electronic control device 250 includes an electric motor control unit 252 as an electric motor control unit, a transmission control unit 254 as a transmission control unit, an electrical insulation performance judgment unit 256 as an electrical insulation performance detection unit, and a notification unit 258 as a notification unit.

[0105] For example, when the on / off clutch 208 is engaged, the motor control unit 252 outputs an MG control command signal Sm to the inverter 230, which uses the motor MG as a power source to drive the vehicle 200.

[0106] The electrical insulation performance determination unit 256 determines whether the driving conditions for judging the electrical insulation performance of the oil are met based on whether the power of the electric motor MG is transmitted to the drive wheel 202. For example, the electrical insulation performance determination unit 256 determines whether the driving conditions for judging the electrical insulation performance of the oil are met based on whether the on / off clutch 208 is engaged and whether the specified gear in the automatic transmission 210 is met.

[0107] When the driving conditions that allow for the determination of the electrical insulation performance of the oil are met, the electrical insulation performance determination unit 256 calculates the torque ratio RT based on the following formula (6). In formula (6), Tmgest represents the estimated value of the MG torque Tmg of the motor MG (hereinafter referred to as the estimated MG torque Tmgest), and Tinest represents the estimated value of the input torque Tin input to the transmission input shaft 222 (hereinafter referred to as the estimated input torque Tinest). Here, in the engaged state of the on / off clutch 208, since the motor connecting shaft 220 and the transmission input shaft 222 are connected via the on / off clutch 208, the input torque Tin and the output torque of the motor MG, i.e., the MG torque Tmg, are the same value. Based on formula (6), the torque ratio RT is calculated by dividing the estimated MG torque Tmgest of the motor MG by the estimated input torque Tinest (i.e., the MG torque Tmg of the motor MG).

[0108] RT = Tmgest / Tinest…(6)

[0109] The estimated MG torque Tmgest in Equation (6) is calculated based on the MG rotational speed Nmg detected by the resolver 140 and the applied current Img detected by the current sensor 142. In addition, the estimated input torque Tinest in Equation (6) is calculated, for example, based on the front and rear acceleration G, the gear ratio γat of the automatic transmission 210, etc.

[0110] The electrical insulation performance determination unit 256 calculates the torque ratio RT based on equation (6) and determines whether oil with low electrical insulation performance has been used based on the torque ratio RT. When oil with high electrical insulation performance is used, the leakage of current is less, so the estimated MG torque Tmgest is equal to or approximately equal to the estimated input torque Tinest. That is, the torque ratio RT is a value of 1.0 or around 1.0. On the other hand, when oil with low electrical insulation performance is used, the leakage of current is increased, so the estimated input torque Tinest is smaller relative to the estimated MG torque Tmgest. That is, the torque ratio RT is greater than 1.0, and the lower the electrical insulation performance, the larger the torque ratio RT is. Therefore, it is possible to determine whether oil with low electrical insulation performance has been used based on the torque ratio RT calculated by equation (6). Furthermore, the control operation of the electrical insulation performance determination unit 256 after calculating the torque ratio RT is basically the same as that of the electrical insulation performance determination unit 84 in the above embodiment, so its description is omitted. Furthermore, the control function of the notification unit 258 is basically the same as that of the notification unit 86 in the above embodiment, so its description is omitted.

[0111] As described above, even a vehicle 200 (electric vehicle) that uses only the electric motor MG as its power source can determine whether oil with low electrical insulation performance has been used based on the electrical insulation performance judgment unit 256 and the notification unit 258. If oil with low electrical insulation performance has been used, the driver can be informed of this intention.

[0112] The embodiments of the present invention have been described in detail above based on the accompanying drawings, but the present invention can also be applied to other forms.

[0113] For example, in Embodiment 1 above, in vehicle 8, the torque ratio RT is calculated based on the torque relationship of the power distribution mechanism 16 (planetary gear unit) (i.e., the relationship of equation (1)), and the electrical insulation performance of the oil is judged based on the value of the torque ratio RT. However, the present invention is not necessarily limited to this form. For example, it is also possible to provide a torque sensor that detects the MG torque Tmg of each motor MG, and calculate the torque ratio RT (=Tmgest / Tmg) based on the estimated MG torque Tmgest estimated based on the applied current Img of each motor MG and the MG torque Tmg detected by the torque sensor, and judge whether the electrical insulation performance of the oil is low based on the torque ratio RT.

[0114] Furthermore, in the above embodiment 2, when the above formula (4) holds during vehicle operation, the torque ratio RT is calculated, and the electrical insulation performance of the oil is determined based on the torque ratio RT. However, the present invention is not necessarily limited to this form. For example, it is also possible to provide a torque sensor that detects the MG torque Tmg of the motor MG, and calculate the torque ratio RT (=Tmgest / Tmg) based on the estimated MG torque Tmgest estimated based on the applied current Img of the motor MG and the MG torque Tmg detected by the torque sensor, and determine whether the electrical insulation performance of the oil is low based on the torque ratio RT.

[0115] Furthermore, in the above embodiment 3, the estimated input torque Tinest is calculated based on the forward and backward acceleration G, etc., but the present invention is not necessarily limited to this form. For example, it is also possible to provide a torque sensor that detects the MG torque Tmg of the motor MG, and calculate the torque ratio RT (=Tmgest / Tmg) based on the estimated MG torque Tmgest estimated based on the applied current Img of the motor MG and the MG torque Tmg detected by the torque sensor, and determine whether the electrical insulation performance of the oil is low based on the torque ratio RT.

[0116] Furthermore, the automatic transmissions 116 and 210 in the above embodiments are known planetary gear type automatic transmissions configured to include one or more sets of planetary gear devices (not shown) and multiple engagement devices CB, but the present invention is not necessarily limited to this. For example, a belt-type continuously variable transmission (CVT) may also be used. That is, the form of the automatic transmission is not particularly limited. In addition, it is not necessarily necessary to provide an automatic transmission; for example, a reduction gear with a constant gear ratio may be provided instead of an automatic transmission. Moreover, the present invention can be applied even in structures that do not have an automatic transmission.

[0117] Furthermore, the above description is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Claims

1. A vehicle (8; 100; 200) comprising an electric motor (MG) functioning as a power source for driving and a power transmission device (10; 104; 204) for transmitting power from the electric motor (MG) to drive wheels (36; 102; 202), characterized in that, The vehicles (8; 100; 200) are equipped with: An electrical insulation performance determination unit (84; 156; 256) determines the electrical insulation performance of the oil supplied to the lubrication requirement unit (34) of the electric motor (MG) and the power transmission device (10; 104; 204); and The notification unit (86; 158; 258) informs the driver of the judgment result of the electrical insulation performance of the oil determined by the electrical insulation performance judgment unit (84; 156; 256). The vehicle (8; 100) is equipped with an engine (12) that functions as a power source different from the electric motor (MG). In the driving state where the power of the engine (12) is distributed to the electric motor (MG) and the specified rotating member (14) mechanically connected to the drive wheel (36; 102), if the torque ratio (RT) calculated by dividing the sum of the estimated torque of the electric motor (MG) and the estimated torque of the specified rotating member (14) by the estimated torque of the engine (12) is greater than or equal to a first threshold (K1), the electrical insulation performance judgment unit (84; 156) judges that the electrical insulation performance of the oil is low and the first threshold (K1) is greater than 1.

0.

2. The vehicle (8; 100; 200) according to claim 1, characterized in that, The electrical insulation performance determination unit (84; 156; 256) determines the electrical insulation performance of the oil based on the relationship between the estimated torque of the motor (MG) calculated based on the current applied to the motor (MG) and the output torque of the motor (MG).

3. The vehicle (8; 100; 200) according to claim 2, characterized in that, If the torque ratio (RT) calculated by dividing the estimated torque of the motor (MG) based on the applied current to the motor (MG) by the output torque of the motor (MG) is greater than or equal to a first threshold (K1), the electrical insulation performance determination unit (84; 156; 256) determines that the electrical insulation performance of the oil is low and the first threshold (K1) is greater than 1.

0.

4. The vehicle (8; 100; 200) according to claim 1 or 3, characterized in that, When the torque ratio (RT) is above the first threshold (K1), the notification unit (86; 158; 258) informs the driver that oil with low electrical insulation properties has been used.

5. The vehicle (8; 100; 200) according to claim 4, characterized in that, The vehicle (8; 100; 200) is configured such that, when the torque ratio (RT) is above a second threshold (K2), the applied current to the electric motor (MG) is reduced, the second threshold (K2) being greater than the first threshold (K1).

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