Oil temperature raising system and method for environmentally friendly vehicles

Abstract

An oil temperature raising system and method for an environmentally friendly vehicle, the system comprising an oil temperature detector and a controller, the oil temperature detector being configured to detect the temperature of oil flowing to a motor and a transmission through an electric oil pump, the controller being configured to receive a detection signal of the oil temperature detector and to apply a current for raising the temperature to the motor when the oil temperature is less than a predetermined reference temperature. The temperature of the motor is raised by the current applied to the motor, so that the oil temperature is raised by the heat of the motor.

Description

Technical Field

[0001] The present invention relates to an oil temperature raising system and method for an environmentally friendly vehicle. More specifically, the present invention relates to a cooling oil temperature raising system and method for an environmentally friendly vehicle, which can apply a current for raising the temperature to a motor in a low temperature environment to raise the temperature of the motor, and can also raise the temperature of oil flowing through an oil circulation channel of the motor, thereby keeping the viscosity of the oil constant. Background Art

[0002] Hybrid vehicles, electric vehicles, hydrogen fuel cell vehicles, etc. are equipped with a motor as a driving source. These vehicles are called environmentally friendly vehicles or electric drive vehicles.

[0003] Generally, an internal combustion engine vehicle equipped with a gasoline engine or a diesel engine is provided with a mechanical oil pump, which is operated by the driving force of the engine that is always driven when the vehicle is traveling. However, the engine included in the powertrain of a hybrid vehicle is not always driven, and an electric vehicle and a fuel cell vehicle do not have an engine, so environmentally friendly vehicles such as hybrid vehicles, electric vehicles, and fuel cell vehicles are equipped with an electric oil pump.

[0004] refer to Figure 1 The powertrain of a hybrid vehicle includes an engine 10 and a motor 12, an engine clutch 11, a transmission 13, a hybrid starter generator (HSG) 14, an inverter 15 and a high-voltage battery 16. The engine 10 and the motor 12 are arranged in series, the engine clutch 11 is arranged between the engine 10 and the motor 12 to transmit or interrupt the power of the engine, the transmission 13 converts the power of the motor or both the motor and the engine and outputs it to the drive wheels, the hybrid starter generator (HSG) 14 is a motor connected to the crankshaft pulley of the engine to generate power for starting the engine and charging the battery, the inverter 15 controls the charging / discharging of the motor 12 and the power generation of the HSG 14, and the high-voltage battery 16 is connected to the motor 12 and the HSG 14 via the inverter 15 for charging and discharging.

[0005] Furthermore, an electric oil pump (EOP) 20 is installed at a predetermined position of a transmission case covering the transmission 13 so as to be driven under the control of an oil pump control unit (OPU) 21. The electric oil pump 20 is applicable not only to electric vehicles and fuel cell vehicles using a motor as a driving source but also to hybrid vehicles.

[0006] Here, although not shown in the drawings, a cooling oil circulation path is formed in the motor 12 and the transmission 13 .

[0007] Therefore, when the oil for cooling and lubrication flows along the oil circulation paths of the motor 12 and the transmission 13 by operating the electric oil pump 20 , the motor 12 and the transmission 13 are cooled.

[0008] For reference, the oil circulated by operating the electric oil pump 20 may be used to cool the motor and the transmission and lubricate the transmission in addition to applying the control hydraulic pressure for shifting.

[0009] The viscosity of the oil circulated by operating the electric oil pump 20 increases in an extremely low temperature environment (eg, -40° C.) In order to circulate the oil having increased viscosity, it is necessary to further increase the output of the electric oil pump.

[0010] In order to circulate oil with increased viscosity in an extremely low temperature environment (e.g., -40°C), it is necessary to additionally increase the output of the electric oil pump. However, since the electric oil pump mounted on a vehicle has a fixed output according to a liter per minute (LPM) standard specification, there is a limitation in increasing the output for circulating high viscosity oil.

[0011] In addition, as a method of making high-viscosity oil circulate easily, the electric oil pump can be replaced with a specification having an increased output capacity. However, the problem is that due to the increase in the size of the electric oil pump, the packageability and assembly may be deteriorated, and the cost may be greatly increased.

[0012] The above content is only intended to help understand the background technology of the present invention, and does not mean that the present invention falls within the scope of the prior art known to those skilled in the art. Summary of the invention

[0013] The present invention is made to solve the above-mentioned problems in the prior art. An object of the present invention is to provide an oil temperature increasing system and method for environmentally friendly vehicles, wherein, when the oil temperature is less than a predetermined reference temperature, a current for heating is applied to the motor, thereby increasing the temperature of the motor, and at the same time, the temperature of the oil flowing through the oil circulation channel of the motor is increased, thereby maintaining the viscosity of the oil, so that the oil can be easily circulated by an electric oil pump.

[0014] To achieve the purpose of the present invention, according to one aspect of the present invention, an oil temperature increasing system for an environmentally friendly vehicle includes: an oil temperature detector and a controller, wherein the oil temperature detector is configured to detect the temperature of oil flowing to a motor and a transmission through an electric oil pump, and the controller is configured to receive a detection signal from the oil temperature detector and apply a current for increasing the temperature to the motor when the oil temperature is less than a predetermined reference temperature; wherein the temperature of the motor can be increased by the current applied to the motor, so that the oil temperature can be increased by the heat of the motor.

[0015] The controller may be configured to apply a d-axis current to the motor as a current for heating when the gear position of the vehicle is the P gear.

[0016] When applying the d-axis current for temperature increase to the motor, the controller may apply the current at a predetermined gradient for a predetermined period of time to reach a maximum d-axis current value.

[0017] When the gear position of the vehicle is D gear, the controller may be configured to apply a current for temperature increase to the motor and select an operating point where the current is applied maximally on an isotorque line of a current map for driving the motor.

[0018] After applying the current for temperature increase to the motor, when it is detected that the oil temperature is equal to or greater than a predetermined reference temperature, the controller may stop applying the current for temperature increase to the motor.

[0019] According to another aspect of the present invention, a method for increasing the oil temperature of an environmentally friendly vehicle includes: detecting the temperature of oil flowing to a motor and a transmission through an electric oil pump by an oil temperature detector; applying a current for increasing the temperature to the motor by a controller when a detection signal from the oil temperature detector is received and the oil temperature is less than a predetermined reference temperature; wherein when the temperature of the motor increases by applying the current to the motor, the temperature of the oil increases by the heat of the motor.

[0020] When the gear position of the vehicle is P gear, the controller can apply a d-axis current to the motor as a current for heating.

[0021] When a d-axis current for temperature increase is applied to the motor, the current may be applied at a predetermined gradient for a predetermined period of time to reach a maximum d-axis current value.

[0022] When the gear position of the vehicle is the D gear, the controller may change the operating point of the motor to an operating point where the current is applied maximally on an equal torque line of a current map for driving the motor.

[0023] After the oil temperature increases, when it is detected that the oil temperature is equal to or greater than a predetermined reference temperature, the controller may stop applying the current for temperature increase to the motor.

[0024] By achieving the above object, the present invention provides the following effects.

[0025] First, when the vehicle is parked or driving under low temperature environmental conditions, a current for heating is applied to the motor to increase the temperature of the motor, and the heat of the motor caused by the temperature increase is transferred to the oil flowing through the oil circulation channel of the motor, thereby preventing the viscosity of the oil from increasing in the low temperature environment while maintaining the viscosity of the oil so that the oil can be easily circulated by the electric oil pump.

[0026] Secondly, control operation is performed so that only current for temperature increase is applied to the motor without replacing the electric oil pump to a specification with increased output capacity, thereby achieving cost reduction, and an existing electric oil pump can be used without special modification, thereby optimizing packageability for each vehicle type. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and other objects, features, and other advantages of the present invention will be more clearly understood from the following detailed description presented in conjunction with the accompanying drawings, in which:

[0028] Figure 1 is a power transmission schematic diagram showing one example of a powertrain of a hybrid vehicle;

[0029] Figure 2 is a control block diagram showing an oil temperature increasing system for an environmentally friendly vehicle according to an exemplary embodiment of the present invention;

[0030] Figure 3 is a flowchart showing an oil temperature increasing method for an environmentally friendly vehicle according to an exemplary embodiment of the present invention;

[0031] Figure 4 is a graph showing a method of applying a current for temperature increase to a motor to increase oil temperature when the eco-friendly vehicle according to an exemplary embodiment of the present invention stops;

[0032] Figure 5 is a graph showing a method of applying a current for temperature increase to a motor to increase oil temperature when the environmentally-friendly vehicle according to an exemplary embodiment of the present invention travels; and

[0033] Figure 6 is a graph showing test example results of an oil temperature increase test when an eco-friendly vehicle according to an exemplary embodiment of the present invention is stopped. DETAILED DESCRIPTION

[0034] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0035] As mentioned above Figure 1 As described, among the components of the powertrain of the hybrid vehicle, the electric oil pump 20 driven under the control of the oil pump control unit 21 is installed at a predetermined position of the transmission case covering the transmission 13, and an oil circulation path for cooling is formed in the motor 12 and the transmission 13.

[0036] Thus, when the oil for cooling and lubrication flows along the oil circulation paths of the motor 12 and the transmission 13 by operating the electric oil pump 20 , the motor 12 and the transmission 13 are cooled.

[0037] However, in a low temperature environment where the temperature is less than a predetermined reference temperature, the viscosity of the oil circulated by operating the electric oil pump 20 increases. In order to circulate the oil with increased viscosity, it is necessary to further increase the output of the electric oil pump. However, since the output pump of the electric oil has a fixed output according to a liter / minute (LPM) standard specification, there is a limitation in increasing the output for circulating high viscosity oil.

[0038] Meanwhile, a driving motor applied to a hybrid vehicle or an electric vehicle mainly uses an interior permanent magnet synchronous motor (IPMSM) configured to embed a permanent magnet in a rotor.

[0039] In the case of an interior permanent magnet synchronous motor, the rotational torque of the rotor is generated by the interaction between the rotating magnetic field generated by the three-phase current applied to the stator coil and the magnetic field of the permanent magnet of the rotor core.

[0040] Here, the amount of heat generated is proportional to the square of the current applied to the stator coil.

[0041] In view of the problem that there are limitations in increasing the output of an electric oil pump to a level for circulating high-viscosity oil and the problem of heat generated by the current applied to the stator coil, an object of the present invention is to increase the temperature of the motor by applying a current for heating the motor when a vehicle is parked and driving under low-temperature environmental conditions, and transfer the heat of the motor caused by the temperature increase to the oil flowing through the oil circulation channel of the motor, thereby preventing the viscosity of the oil from increasing in a low-temperature environment while maintaining the viscosity of the oil, thereby facilitating the circulation of the oil through the electric oil pump.

[0042] refer to Figure 2 According to an exemplary embodiment of the present invention, the oil temperature increasing system includes: an oil temperature detector 30 and a controller 40, wherein the oil temperature detector 30 detects the temperature of the oil circulated to the motor 12 and the transmission 13 through the electric oil pump 20, and the controller 40 receives the detection signal of the oil temperature detector 30 and applies a current for heating to the motor 12 when the oil temperature is less than a predetermined reference temperature.

[0043] The oil temperature detector 30 may include an oil temperature sensor that detects the temperature of oil discharged from the electric oil pump 20 and supplied to the motor 12 and the transmission 13 .

[0044] like Figure 2 As shown, the controller 40 can be composed of a single integrated controller or multiple controllers including a hybrid controller 42 and a motor controller 43, wherein the hybrid controller 42 is the highest controller for receiving the detection signal of the oil temperature detector 30 and the current gear signal of the transmission controller 41, thereby issuing a command for the current of the motor 12, and the motor controller 43 controls the current of the motor 12 according to the current command of the hybrid controller 42.

[0045] Specifically, the controller 40 is configured to receive the detection signal of the oil temperature detector 30 and the current gear signal of the transmission controller 41, and apply a current for heating to the motor 12 when the oil temperature is less than a predetermined reference temperature, and apply the current for heating in different manners in the P gear (when parked) and the forward (D) gear (when driving).

[0046] The controller 40 can be configured to receive a detection signal from the oil temperature detector 30, thereby applying a current for heating to the motor 12 when the oil temperature is less than a predetermined reference temperature, and to receive a current gear signal from the transmission controller 41, thereby applying a d-axis current to the motor 12 as a current for heating when the vehicle's gear is P gear.

[0047] At this time, if the d-axis current I is applied to the motor 12 when the vehicle is parked (the vehicle is parked by the P gear). d , due to the q-axis current I q is zero, the driving torque T of the motor 12 becomes zero according to the torque equation described in the following equation 1.

[0048] [Equation 1]

[0049]

[0050] In the above equation 1, ψ m I q represents the torque caused by the field flux, (L d -L q )I d I q Represents the torque caused by magnetic resistance.

[0051] Thus, when the vehicle is parked in the P gear, only the d-axis current I is applied to the motor 12. d , while the q-axis current I q Therefore, in a state where the driving torque of the motor 12 that causes the motor 12 to rotate is not generated, the temperature of the motor 12 easily rises.

[0052] In other words, in a state where the motor 12 is not rotated by the d-axis current applied to the motor 12 (ie, the d-axis current applied to the stator coil), heat is generated, so that the temperature of the motor 12 rises.

[0053] Subsequently, when the heat of the motor 12 caused by the temperature increase of the motor 12 is transferred to the oil flowing through the oil circulation channel 12-1 of the motor 12, the oil temperature rises, thereby preventing the viscosity of the oil from increasing in a low temperature environment, while maintaining the viscosity of the oil, thereby facilitating the circulation of the oil through the electric oil pump.

[0054] The driving torque of the motor 12 may be generated due to errors such as the angle of the rotary transformer of the motor 12. However, since the torque that the parking gear can withstand in the P gear is designed to be three times or more of the maximum torque of the motor, when the vehicle is parked in the parking (P) gear, even if the d-axis current I is applied to the motor, the torque of the motor 12 is 0.1 times the maximum torque of the motor. d , it can also prevent damage to the parking gear and movement of the vehicle.

[0055] In P gear, due to the gap between the teeth of the parking gear, impact may occur due to the generation of instantaneous torque of the motor, such as Figure 4 As shown, when applying a d-axis current for temperature increase to the motor, the controller 40 applies the current at a predetermined gradient within a predetermined period of time to reach a maximum d-axis current value, thereby easily preventing a surge phenomenon caused by generation of instantaneous torque of the motor.

[0056] The controller 40 can be configured to receive the detection signal of the oil temperature detector 30, thereby applying a current for heating to the motor 12 when the oil temperature is less than a predetermined reference temperature, and receive the current gear signal of the transmission controller 41, so that when the gear of the vehicle is D gear, a working point is selected on the equal torque line of the current mapping diagram for driving the motor to apply the maximum current.

[0057] The current map is the mapping data contained in the controller, which is used to control the current (torque) of the motor.

[0058] For reference, Figure 5 As shown, a current mapping diagram can be formed so that within the current limit range (through Figure 5 The current limit circle in the figure shows that there are multiple equal torque lines T 1 、T 2 ,...T max , and there are multiple operating points along each equal torque line, at which the current applied to the motor varies.

[0059] Figure 5 The Maximum Torque Per Ampere (MTPA) shows a curve with the maximum torque magnitude per unit current.

[0060] Therefore, when the oil temperature is less than a predetermined reference temperature and the gear position of the vehicle is the D gear, the controller 40 changes the operating point of the motor to an operating point where current is applied maximally on an isotorque line of a current map for driving the motor.

[0061] For example, when the controller controls the torque of the motor during vehicle driving, the torque can be controlled using the operating point that exists along the MTPA curve (the operating point that produces the minimum current and the maximum torque). Figure 5As shown by the arrow, the working point is changed to the working point on the equal torque line where the current can be applied maximally, that is, the q-axis current can be reduced but the d-axis current can be increased to the maximum working point.

[0062] Thus, when the oil temperature is less than a predetermined reference temperature and the gear position of the vehicle is the D gear, the controller 40 changes the working point of the motor to a working point where the current is applied to the maximum on the isotorque line of the current map for driving the motor, so that the current for temperature increase can be further applied to the motor 12. In addition, the heat of the motor caused by the increase in the motor temperature is transferred to the oil flowing through the oil circulation channel 12-1 of the motor, so that the oil temperature can be rapidly increased while the vehicle is running. Thus, the viscosity of the oil can be prevented from increasing in a low temperature environment, and at the same time, the viscosity of the oil can be maintained, so that the oil can be easily circulated by the electric oil pump.

[0063] Here, the oil temperature increasing method for an environmentally friendly vehicle according to the present invention will be described in sequence.

[0064] Figure 3 is a flowchart showing an oil temperature increasing method for an environmentally friendly vehicle according to an exemplary embodiment of the present invention.

[0065] First, the oil temperature detector 30 detects the temperature of the oil circulated to the motor 12 and the transmission 13 by the electric oil pump, and then transmits the oil temperature to the controller 40 .

[0066] Subsequently, in step S101 , the controller 40 checks whether the oil temperature is less than a predetermined reference temperature k.

[0067] Based on the checking result, when the oil temperature is less than the predetermined reference temperature, in steps S102 and S103 , a current gear position signal of the transmission controller 41 is received, thereby identifying the current gear position.

[0068] When the current gear is identified as the P gear in step 102 , the controller 40 applies the d-axis current I to the motor 12 d More specifically, in step S104, the controller applies a current at a predetermined gradient for a predetermined period of time so as to reach a maximum d-axis current value.

[0069] Thus, when the vehicle is parked in the P gear, only the d-axis current I d , while the q-axis current I q is zero, so that no driving torque of the motor causing the motor to rotate is generated.

[0070] Thus, in a state where the motor is not rotating due to the d-axis current applied to the motor 12 (ie, the d-axis current applied to the stator coil), heat is generated, so that the temperature of the motor rises.

[0071] Subsequently, when the heat of the motor caused by the temperature increase of the motor 12 is transferred to the oil flowing through the oil circulation channel 12-1 of the motor 12, the oil temperature rises, thereby preventing the viscosity of the oil from increasing in a low temperature environment while maintaining the viscosity of the oil, thereby easily circulating the oil through the electric oil pump.

[0072] Reference is made to the test examples showing the present invention. Figure 6 It can be seen that when the d-axis current of 280A is applied to the motor 12 in the P gear, the motor temperature rises from 29°C to 66°C and the oil temperature rises from 28°C to 45°C. This shows that the oil temperature can be increased by simply applying the d-axis current to the motor 12 in a low temperature environment.

[0073] On the other hand, when the current gear of the vehicle is identified as the D gear in step S103 , the controller 40 changes the operating point of the motor 12 to an operating point where the current is maximally applied on the isotorque line of the current map for driving the motor 12 in step S105 .

[0074] In this way, the controller 40 changes the working point of the motor 12 to the working point where the current is applied to the maximum on the isotorque line of the current map for driving the motor 12, so that the current for temperature increase can be further applied to the motor 12. In addition, the heat of the motor caused by the increase in the motor temperature is transferred to the oil flowing through the oil circulation channel 12-1 of the motor, so that the oil temperature is rapidly increased while the vehicle is running. Thus, the viscosity of the oil can be prevented from increasing in a low temperature environment, while the viscosity of the oil is maintained, so that the oil can be easily circulated by the electric oil pump.

[0075] After the step of increasing the oil temperature, in step S106, the oil temperature is compared with a reference temperature k. Here, when the oil temperature detected within a predetermined period of time is equal to or greater than a predetermined reference temperature, in step S107, the controller performs a control operation to stop applying a current for temperature increase to the motor.

[0076] Although the present invention has been described with reference to the specific embodiments shown in the drawings, it will be apparent to those skilled in the art that the present invention can be changed and modified in various ways without departing from the scope of the invention as described in the claims.

Claims

1. An oil temperature raising system for an environmentally friendly vehicle, the system include: an oil temperature detector configured to detect the temperature of oil flowing to the motor and the transmission through the electric oil pump; and The controller is configured as: Receiving a detection signal from an oil temperature detector; When the oil temperature is less than a predetermined reference temperature, applying a current for heating the motor; wherein the temperature of the motor is increased by the current applied to the motor, so that the oil temperature is increased by the heat of the motor; Wherein, the controller is configured to: when the gear position of the vehicle is the parking gear, apply a current for heating to the motor as a d-axis current; When the gear of the vehicle is the forward gear, the controller is configured to apply a current for heating to the motor and select a working point on an isotorque line of a current map for driving the motor where the current is applied maximally.

2. The oil temperature raising system for an environmentally friendly vehicle according to claim 1, in, The controller applies a d-axis current for temperature increase to the motor at a predetermined gradient within a predetermined period of time to reach a maximum d-axis current value.

3. The oil temperature raising system for an environmentally friendly vehicle according to claim 1, in, After applying the current to the motor, the controller stops applying the current to the motor when detecting that the oil temperature is equal to or greater than a predetermined reference temperature.

4. A method for increasing the oil temperature of an environmentally friendly vehicle, the method include: The oil temperature detector detects the temperature of the oil flowing to the motor and the transmission through the electric oil pump; When a detection signal from the oil temperature detector is received and the oil temperature is less than a predetermined reference temperature, a current for heating the motor is applied to the motor through the controller; When the temperature of the motor increases by applying the current to the motor, the temperature of the oil increases by the heat of the motor; Wherein, when applying the current for heating to the motor, if the gear position of the vehicle is the parking gear, the controller applies the current to the motor as the d-axis current; When applying current for heating to the motor, if the gear of the vehicle is a forward gear, the controller selects a working point where the current is applied maximally on an isotorque line of a current map for driving the motor.

5. The method according to claim 4, in, A d-axis current is applied to the motor at a predetermined gradient for a predetermined period of time to reach a maximum d-axis current value.

6. The method according to claim 4, in, After applying current for temperature increase to the motor, the controller stops applying the current to the motor when detecting that the oil temperature is equal to or greater than a predetermined reference temperature.

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