JP2016028926A - Hybrid electric vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the leakage of a working fluid from a breather and suppress the degradation of drivability if a hybrid electric vehicle runs on a downhill.SOLUTION: An ECU executes control processing including a step (S102) of correcting a threshold da(0) on the basis of a state of high-voltage-system electrical equipment and a step (S104) of correcting the threshold value da(0) on the basis of a battery SOC if a vehicle is running on a downhill (YES in S100); and a step (S110) of engaging a K0 clutch and a step (S112) of disengaging a K2 clutch if a deceleration is lower than the threshold da(0) (YES in S106) and a revolving speed of a MG is higher than a threshold Nm(0) (YES in S108).SELECTED DRAWING: Figure 3

Description

  The present invention relates to a hybrid vehicle equipped with a transmission having an input shaft connected to an engine via a first clutch and a motor generator connected to the input shaft of the transmission via a second clutch.

  Japanese Patent Laid-Open No. 2008-074254 (Patent Document 1) includes an engine, a transmission, and a motor generator coupled to each of the engine and the transmission via a clutch between the engine and the transmission. A hybrid vehicle is disclosed. Patent Document 1 discloses that a clutch provided between a motor generator and a transmission is released when a hybrid vehicle travels on a downhill. Also, a breather for releasing the internal pressure is provided in the housing for housing the above-described transmission and the housing for housing the motor generator.

JP 2008-074254 A JP 05-308702 A

  By the way, when the hybrid vehicle travels downhill, the hydraulic oil may be biased toward the front side of the vehicle. In such a case, the motor generator is disposed in front of the transmission, and the inside of the housing that houses the motor generator and the inside of the housing that houses the transmission are in fluid communication with each other. If so, the hydraulic oil may be biased toward the motor generator side. For this reason, the hydraulic oil is agitated by the rotation of the motor generator, and the hydraulic oil may leak from a breather provided in a housing that houses the motor generator. To solve such a problem, as in the hybrid vehicle described in Patent Document 1 described above, when the vehicle travels on a downhill, the clutch provided between the motor generator and the transmission is released. However, when the connection state between the engine and the transmission is released, the deceleration of the vehicle may change and drivability may deteriorate.

  The present invention has been made to solve the above-described problems, and its object is to suppress the leakage of hydraulic oil from the breather and to deteriorate the drivability when the hybrid vehicle travels downhill. It is providing the hybrid vehicle which suppresses.

  A vehicle according to an aspect of the present invention includes an engine, a transmission having an input shaft coupled to the engine via a first clutch, and a motor generator coupled to the input shaft of the transmission via a second clutch. A first housing that houses the transmission, a second housing that is provided in front of the vehicle relative to the first housing and houses the motor generator, and a control device that controls the first clutch and the second clutch Is provided. The inside of the 1st case and the inside of the 2nd case are connected so that hydraulic oil can move. A breather is provided in the second casing. When the vehicle travels on a downhill, the control device puts the second clutch into a released state and puts the first clutch into an engaged state.

  According to the present invention, when the vehicle travels on a downhill, the second clutch is in a released state, so that an increase in the rotational speed of the motor generator can be suppressed. Therefore, it is possible to suppress leakage of hydraulic oil from the breather provided in the second housing. Furthermore, since the first clutch is engaged, the engine and the transmission are connected. As a result, it becomes possible to generate engine braking, so that changes in vehicle deceleration can be suppressed and deterioration of drivability can be suppressed. Therefore, when the hybrid vehicle travels downhill, it is possible to provide a hybrid vehicle that suppresses leakage of hydraulic oil from the breather and suppresses deterioration of drivability.

It is a figure which shows the structure of a hybrid vehicle. It is a conceptual diagram which shows the change of the oil level when the vehicle travels on a downhill and when traveling on a flat road. It is a flowchart which shows the control processing performed by ECU.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

  As shown in FIG. 1, a hybrid vehicle (hereinafter simply referred to as a vehicle) 1 according to the present embodiment includes an engine 10, a K0 clutch 12, a K2 clutch 14, and a motor generator (hereinafter referred to as MG). ) 20, a PCU (Power Control Unit) 22, a battery 24, a torque converter 30, a hydraulic circuit 32, a transmission 40, drive wheels 50, and an ECU (Electronic Control Unit) 100.

  The engine 10 is an internal combustion engine such as a gasoline engine or a diesel engine. A crankshaft that is an output shaft of engine 10 is connected to an input shaft of torque converter 30 with K0 clutch 12 interposed.

  The K0 clutch 12 is engaged when a power transmission state is established between the output shaft of the engine 10 and the input shaft of the torque converter 30, and the power is cut off between the output shaft of the engine 10 and the input shaft of the torque converter 30. Release to put in a state.

  MG 20 is, for example, a three-phase AC rotating electric machine. The MG 20 is driven by electric power supplied from the battery 24 via the PCU 22. The MG 20 has a function as a motor that generates the driving force of the vehicle 1, a function as a starter that starts the engine 10, and a function as a generator that generates electric power by receiving reaction force from the engine power or road surface.

  The rotation shaft of MG 20 is connected to the input shaft of torque converter 30 via K2 clutch 14. The output shaft of the torque converter 30 is connected to the input shaft of the transmission 40. An output shaft of the transmission 40 is connected to the drive wheels 50.

  Torque converter 30 includes a pump impeller coupled to the rotation shaft of MG 20, a turbine impeller coupled to the input shaft of transmission 40, and a stator provided between the pump impeller and the turbine impeller. The rotation and the rotation of the input shaft and the output shaft of the torque converter 30 are released when the lockup clutch is engaged, and the rotation is released when the lockup clutch is released.

  The transmission 40 is a stepped automatic transmission that continuously and automatically changes a plurality of shift stages. The transmission includes a brake and a clutch for forming a plurality of shift speeds. The transmission 40 may be another type of automatic transmission such as a continuously variable transmission or a manual transmission.

  The hydraulic circuit 32 includes a mechanical oil pump (hereinafter also referred to as MOP (Mechanical Oil Pump)) 34. The MOP 34 operates with the rotation of the input shaft of the torque converter 30 and the pump impeller using the engine 10 or the MG 20 as a power source. The MOP 34 supplies hydraulic oil stored in an oil pan (see FIG. 2) provided below the transmission 40 to a supply target such as a solenoid valve in the hydraulic circuit 32.

  The hydraulic circuit 32 adjusts the hydraulic pressure of the hydraulic oil supplied from the MOP 34 based on a control signal from the ECU 100 using various regulating valves such as a solenoid valve, and then in the K0 clutch 12, the K2 clutch 14, and the transmission 40. Supply hydraulic oil to brakes and clutches.

  The brakes and clutches in the K0 clutch 12, the K2 clutch 14, and the transmission 40 are both moved by the hydraulic oil supplied from the hydraulic circuit 32, and the clutch piston is moved, and each clutch transmits and receives power. Engage with the rotating bodies (drive plate and driven plate provided with the friction material) by applying a force so that friction is generated and the relative rotation between the rotating bodies is eliminated (that is, the two rotating bodies rotate). Synchronize). The K0 clutch 12 is, for example, a wet multi-plate clutch. The K2 clutch 14 is, for example, a dog clutch.

  The ECU 100 controls the hydraulic circuit 32 so that at least one of the K0 clutch 12, the K2 clutch 14, and the clutch and brake in the transmission 40 is engaged or released according to the driving state of the vehicle 1.

  The ECU 100 engages the K0 clutch 12 when the operation of the engine 10 is requested, for example, when the K0 clutch 12 is in a released state and the engine 10 is in a stopped state. Thereby, it will be in the power transmission state between the engine 10 and MG20. Therefore, the engine 10 can be operated by cranking the engine 10 by the MG 20 or by cranking the engine 10 by the rotation of the rotation shaft of the MG 20 when the vehicle 1 is coasting. When the engine 10 operates, the vehicle 1 travels using the power of the engine 10 or the power of the engine 10 in addition to the power of the engine 10. Further, the battery 24 can be charged by power generation using the MG 20 by the operation of the engine 10 or power generation using the MG 20 when the vehicle 1 is coasting.

  On the other hand, for example, when the K0 clutch 12 is in the engaged state and the engine 10 is in the operating state, the ECU 100 releases the K0 clutch 12 and fuel injection when the engine 10 is requested to stop. To stop the operation of the engine 10.

  The ECU 100 requests the operation of the engine 10 or requests the engine 10 to be stopped according to the driving state of the vehicle 1. The ECU 100 calculates, for example, the power (required power) required for the vehicle 1 based on the depression amount of an accelerator pedal (not shown) and the speed of the vehicle 1, and when the required power exceeds a threshold value, the engine 10 May be requested, or the engine 10 may be requested to stop when the requested power is below the threshold value.

  The vehicle 1 further includes a gradient sensor 102, a battery temperature sensor 104, a current sensor 106, a voltage sensor 108, a resolver 110, and an output shaft rotation speed sensor 112 as various sensors.

  The gradient sensor 102 detects the gradient A of the road surface on which the vehicle 1 travels. The gradient sensor 102 transmits a detection signal indicating the road surface gradient A to the ECU 100.

  The battery temperature sensor 104 detects the temperature TB of the battery 24. The battery temperature sensor 104 transmits a detection signal indicating the temperature TB of the battery 24 to the ECU 100.

  The current sensor 106 detects the current IB of the battery 24. Current sensor 106 transmits a detection signal indicating current IB of battery 24 to ECU 100.

  The voltage sensor 108 detects the voltage VB of the battery 24. Voltage sensor 108 transmits a detection signal indicating voltage VB of battery 24 to ECU 100.

  The resolver 110 detects the rotation angle θ of the rotation shaft of the MG 20. Resolver 110 transmits a detection signal indicating the rotation angle θ of the rotation shaft of MG 20 to ECU 100. ECU 100 calculates rotation speed Nm of MG 20 based on the detection signal from resolver 110.

  The output shaft rotational speed sensor 112 detects the rotational speed No of the output shaft of the transmission 40. The output shaft rotational speed sensor 112 transmits a detection signal indicating the rotational speed No of the output shaft of the transmission 40 to the ECU 100. ECU 100 calculates speed V of vehicle 1 based on the detection signal from output shaft rotation speed sensor 112.

  Furthermore, as shown in FIG. 2, the MG 20, the torque converter 30, the transmission 40, and the hydraulic circuit 32 are housed in a transmission case 60. As described above, MG 20 is coupled to the input shaft of torque converter 30. The transmission 40 is connected to the output shaft of the torque converter 30. In the transmission case 60, the inside of the housing part that houses the MG 20 and the inside of the housing part that houses the transmission 40 are in fluid communication with each other. A breather 42 is provided on the upper portion of the housing portion that houses the MG 20. The breather 42 is an adjustment valve that relieves pressure in the housing that houses the MG 20. In addition, breathers 44 and 46 are provided on the upper portion of the housing portion that houses the transmission 40. The breathers 44 and 46 are regulating valves that relieve the pressure in the housing that houses the transmission 40.

  In the present embodiment, as shown by a two-dot chain line in FIG. 2, an air chamber that is distinguished from the movable range of hydraulic oil between MG 20 and transmission 40 is formed around torque converter 30. Shall be.

  When the vehicle 1 having the above configuration travels on a downhill, when traveling on a flat road surface as shown in the oil level surface of the one-dot chain line (thin line) in FIG. 2 (the one-dot chain line (thick line in FIG. 2)). The hydraulic oil may be biased toward the front side of the vehicle 1 as compared with the oil level surface of)). The oil level surface shown in FIG. 2 is conceptually shown to explain the change between the flat road and the downhill. In such a case, the MG 20 is disposed in front of the vehicle 1 relative to the transmission 40, and the hydraulic oil can move between the inside of the housing that houses the MG 20 and the inside of the housing that houses the transmission 40. Therefore, the hydraulic oil is biased toward the MG 20 side, and the oil level surface in the MG 20 rises. Therefore, the hydraulic oil may be agitated by the rotation of the MG 20, and the hydraulic oil may leak from the breather 42 provided in the casing portion that houses the MG 20. In such a case, it is conceivable to disengage the K2 clutch 14 provided between the MG 20 and the input shaft of the transmission 40. However, if the transmission 40 is disconnected from the MG 20 and the engine 10, the vehicle Since 1 travels downhill, the deceleration of the vehicle 1 may change, and drivability may deteriorate.

  Therefore, in the present embodiment, when the vehicle 1 travels on a downhill, the ECU 100 sets the K0 clutch 12 and the K2 clutch 14 so that the K2 clutch 14 is released and the K0 clutch 12 is engaged. It is characterized in that it is controlled.

  In this way, when the vehicle 1 travels on a downhill, the K2 clutch 14 is in a released state, so that an increase in the rotational speed of the MG 20 can be suppressed. Therefore, it is possible to suppress the hydraulic oil from leaking from the breather 42 provided in the casing of the MG 20. Furthermore, since the K0 clutch 12 is engaged, the engine 10 and the transmission 40 are connected. Therefore, it becomes possible to generate an engine brake, so that a change in deceleration of the vehicle 1 can be suppressed and deterioration of drivability can be suppressed.

  With reference to FIG. 3, a control process executed by ECU 100 mounted on vehicle 1 according to the present embodiment will be described.

  In step (hereinafter, step is referred to as S) 100, ECU 100 determines whether or not vehicle 1 is traveling downhill. ECU 100 determines, for example, whether the vehicle 1 is traveling with speed V greater than threshold value V (0). Further, the ECU 100 determines whether or not the road surface on which the vehicle 1 travels is a downhill in which the magnitude of the gradient A of the road is greater than the threshold value A (0). If it is determined that vehicle 1 is traveling downhill (YES in S100), the process proceeds to S102. If not (NO in S100), the process proceeds to S114.

  In S102, ECU 100 corrects threshold value da (0) based on the state of the high-voltage electrical device. The threshold value da (0) is a threshold value of a deceleration da for determining whether or not to release the K2 clutch 14, which will be described later, and is a negative value. Examples of the high-voltage electric device include MG 20, PCU 22, and battery 24. The state of the high-voltage electrical device is, for example, the temperature state of the MG 20, the PCU 22, and the battery 24.

  As the temperature of the high-voltage electric device increases, the ECU 100 decreases the upper limit value (allowable value) of the deceleration that enables regenerative braking using the high-voltage electric device. Correction is performed so that the size of da (0) is reduced. On the other hand, the ECU 100 corrects the threshold value da (0) so that the upper limit value increases as the temperature of the high-voltage electrical device decreases. The ECU 100 calculates, for example, a first correction coefficient C1 based on the temperature state of the high-voltage electric device using a map or the like, and multiplies the initial value of the threshold da (0) by the first correction coefficient C1. The threshold value after correction may be used.

  In S104, ECU 100 corrects threshold value da (0) based on the SOC of battery 24. ECU 100 calculates an SOC (State Of Charge) of battery 24 based on temperature TB, current IB, voltage VB, and the like of battery 24. For example, ECU 100 may calculate the SOC by estimating the open circuit voltage, or may calculate the SOC based on the integrated value of the charge / discharge current. Since the ECU 100 becomes more difficult to perform regenerative braking as the SOC increases, the threshold da (0) is a negative value so that the threshold da (0) is a negative value. Correct it so that it becomes larger. ECU 100 calculates, for example, a second correction coefficient C2 based on the SOC of battery 24 using a map or the like, and corrects a value obtained by multiplying threshold da (0) calculated in S102 by second correction coefficient C2. The threshold da may be used.

  In S106, ECU 100 determines whether or not deceleration da is smaller than threshold value da (0). In the present embodiment, the positive value of the deceleration da indicates the acceleration in the acceleration direction of the vehicle 1, and the negative value of the deceleration da indicates the acceleration in the deceleration direction of the vehicle 1. The threshold value da (0) is a negative value. That is, the state in which the deceleration da is smaller than the threshold value da (0) is a deceleration state in which the magnitude of acceleration in the deceleration direction of the vehicle 1 is larger than the threshold value da (0). For example, ECU 100 may calculate deceleration da by differentiating vehicle speed V with time, or may calculate deceleration da using a G sensor or the like. If it is determined that deceleration da is smaller than threshold value da (0) (YES in S106), the process proceeds to S108. If not (NO in S106), the process proceeds to S114.

  In S108, ECU 100 determines whether or not rotational speed Nm of MG 20 is greater than threshold value Nm (0). The threshold value Nm (0) is, for example, a predetermined value, and is the rotational speed of the MG 20 at which hydraulic oil may leak from the breather 42 when the vehicle 1 travels downhill. The threshold value Nm (0) is adapted, for example, by design or experiment. If it is determined that the rotation speed of MG 20 is greater than threshold value Nm (0) (YES in S108), the process proceeds to S110. If not (NO in S108), the process proceeds to S114.

  In S110, ECU 100 brings K0 clutch 12 into an engaged state. In S112, ECU 100 brings K2 clutch 14 into a released state. In S114, ECU 100 brings K2 clutch 14 into an engaged state.

  The operation of ECU 100 mounted on vehicle 1 according to the present embodiment based on the above-described structure and flowchart will be described.

  For example, it is assumed that the vehicle 1 is traveling downhill. Since the vehicle is traveling on a downhill (YES in S100), threshold value da (0) is corrected based on the temperature state of the high-voltage electrical equipment (S102), and based on the SOC of battery 24. The threshold value da (0) is further corrected (S104). And when deceleration da of vehicle 1 is a deceleration state smaller than threshold value da (0) (YES in S106), and rotational speed Nm of MG 20 is above threshold value Nm (0). Is larger (YES in S108), the K0 clutch 12 is engaged (S110), and the K2 clutch 14 is released (S112).

  When the K2 clutch 14 is released, the connection between the MG 20 and the input shaft of the transmission 40 is released, so that an increase in the rotational speed of the MG 20 is suppressed, and leakage of hydraulic oil from the breather 42 is suppressed. . On the other hand, when the K0 clutch 12 is engaged, the engine brake due to the friction of the engine 10 acts, so that a large change in the deceleration due to the disconnection of the MG 20 (for example, the magnitude of the deceleration suddenly decreases). Is suppressed.

  When deceleration da is equal to or higher than threshold value da (0) (NO in S106), or when rotation speed Nm of MG 20 is equal to or lower than threshold value Nm (0), K2 clutch 14 is engaged. (S114).

  As described above, according to the vehicle 1 according to the present embodiment, when the vehicle 1 travels downhill, the K2 clutch 14 is in a released state, and therefore, an increase in the rotational speed Nm of the MG 20 is suppressed. Can do. Therefore, it is possible to suppress the hydraulic oil from leaking from the breather 42 provided in the casing of the MG 20. Furthermore, since the K0 clutch 12 is engaged, the engine 10 and the transmission 40 are connected. Therefore, by generating the engine brake, it is possible to suppress a change in the deceleration da of the vehicle 1 and suppress deterioration in drivability. Therefore, when the hybrid vehicle travels downhill, it is possible to provide a hybrid vehicle that suppresses leakage of hydraulic oil from the breather and suppresses deterioration of drivability.

  Furthermore, in the present embodiment, when the vehicle 1 travels on a downhill, the K2 clutch 14 is released only when the deceleration da is in a decelerating state smaller than the threshold value da (0). Execute control. Thereby, fuel consumption can be improved by regenerative braking or the like until a deceleration state smaller than the threshold value da (0) is reached.

  Furthermore, in the present embodiment, when vehicle 1 travels on a downhill, control for releasing K2 clutch 14 is performed only when rotation speed Nm of MG 20 is greater than threshold value Nm (0). Run. Thereby, when the rotation state of the MG 20 is a state where there is a possibility that the hydraulic oil leaks from the breather 42, the K2 clutch 14 can be released and the leakage of the hydraulic oil from the breather 42 can be suppressed. Further, when the rotational state of the MG 20 is a state where there is no possibility of leakage of hydraulic oil from the breather 42, the K2 clutch 14 can be engaged to improve fuel efficiency by regenerative braking or the like.

  Further, by correcting the threshold value da (0) based on the temperature state or the like of the high-voltage electric device, in the deceleration state where regenerative braking is possible, the fuel consumption is improved by regenerative braking and the like, while the high voltage is increased. In the deceleration state exceeding the limit value based on the temperature state of the electrical equipment of the system, it is possible to suppress the hydraulic oil from leaking from the breather 42 by executing the control for releasing the K2 clutch 14.

  Further, by correcting the threshold value da (0) based on the SOC of the battery 24, it is possible to suppress leakage of hydraulic oil from the breather 42 due to execution of control for releasing the K2 clutch 14 in a deceleration state that does not require regenerative braking. can do.

  A modification will be described below. In the present embodiment, it has been described that the K0 clutch 12 is a wet multi-plate clutch and the K2 clutch 14 is a dog clutch. For example, at least one of the K0 clutch 12 and the K2 clutch 14 is: It may be a dry clutch, a wet clutch, or a dog clutch.

  Furthermore, in the present embodiment, the torque converter 30 is described as being provided between the engine 10 and the transmission 40 (or MG 20), but the torque converter 30 may be omitted.

  Furthermore, in the present embodiment, it has been described that the K2 clutch 14 is released and the K0 clutch 12 is engaged when the vehicle is traveling downhill. However, the K0 clutch 12 is engaged. The fuel injection amount of the engine 10 may be stopped, or the fuel injection amount of the engine 10 may be controlled so that the deceleration becomes a target deceleration based on an accelerator pedal, a gear position, etc. Good. In addition, you may implement combining the above-mentioned modification, all or one part.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1 vehicle, 10 engine, 12 K0 clutch, 14 K2 clutch, 20 MG, 22 PCU, 24 battery, 30 torque converter, 32 hydraulic circuit, 40 transmission, 42, 44, 46 breather, 50 drive wheel, 60 transmission case, 100 ECU, 102 Gradient sensor, 104 Battery temperature sensor, 106 Current sensor, 108 Voltage sensor, 110 Resolver, 112 Output shaft rotation speed sensor

Claims (1)

Engine,
A transmission having an input shaft coupled to the engine via a first clutch;
A motor generator coupled to the input shaft of the transmission via a second clutch;
A first housing that houses the transmission;
A second housing that is provided on the front side of the vehicle with respect to the first housing and houses the motor generator;
A control device for controlling the first clutch and the second clutch;
The inside of the first housing and the inside of the second housing are in fluid communication with hydraulic oil,
The second casing is provided with a breather,
The control device is a hybrid vehicle in which, when the vehicle travels on a downhill, the second clutch is disengaged and the first clutch is engaged.

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