JP2019142354A - Hybrid vehicle - Google Patents

Abstract

To provide a hybrid vehicle which enables proper deceleration while suppressing the deterioration of an exhaust gas purification catalyst, and can improve energy efficiency.SOLUTION: In a hybrid vehicle having a catalyst converter, a motor changeable in an engine rotation number by outputting torque by being connected to an engine, a brake mechanism for generating a brake force, and a clutch for selectively blocking power transmission between and among the engine, the motor and drive wheels, and capable of performing a fuel cut during traveling, when the hybrid vehicle is decelerated in order to suppress the deterioration of the catalyst converter in a state that the execution of the fuel cut is prohibited, a required brake force is generated by controlling the brake mechanism, the power transmission is blocked by releasing the clutch, and a rotation number of an output shaft is lowered by controlling the motor (step S129).SELECTED DRAWING: Figure 7

Description

  The present invention relates to a hybrid vehicle equipped with an engine and a motor having a power generation function as a power source.

  Patent Document 1 describes a vehicle control device that is intended to satisfactorily decelerate a vehicle while suppressing deterioration of a catalyst. The vehicle control device described in Patent Document 1 is designed to perform fuel cut when it is necessary to suppress deterioration of an exhaust gas purification catalyst for a hybrid vehicle using an engine and a motor as a driving force source. Ban. When fuel cut is prohibited, the regenerative braking force by the motor is increased.

JP 2009-51466 A

  As described above, when the vehicle is decelerated in a situation where fuel cut is prohibited in order to suppress deterioration of the catalyst, the vehicle is in a state in which the engine is burned so that the combustion state of the engine becomes a so-called stoichiometric. It is necessary to realize the required deceleration for. For this reason, in the vehicle control device described in Patent Document 1 described above, fuel cut is prohibited when it is necessary to suppress deterioration of the catalyst. When fuel cut is performed in a high temperature range where the catalyst is likely to deteriorate, the combustion state of the engine becomes lean and the amount of oxygen entering the catalyst increases. As a result, the catalyst temperature further rises and the deterioration of the catalyst proceeds. Therefore, for example, in the region where the catalyst temperature is high as described above, execution of fuel cut is prohibited.

  On the other hand, if the fuel cut is prohibited during deceleration of the vehicle, the braking force by so-called engine braking is reduced. That is, in a situation where fuel cut is prohibited, the deceleration of the vehicle is lower than when fuel cut is performed. Therefore, in the vehicle control apparatus described in Patent Document 1, when fuel cut is prohibited as described above, the regenerative braking force by the motor is increased. By supplementing the shortage of engine braking caused by prohibiting fuel cut with the regenerative braking force of the motor, both deterioration suppression of the catalyst and realization of deceleration are achieved. Further, the energy efficiency of the vehicle is improved by utilizing the regenerative braking force of the motor.

  However, the vehicle control apparatus described in Patent Document 1 still has room for improvement in order to further improve energy efficiency. In the vehicle control device described in Patent Document 1, when fuel cut is prohibited as described above, regenerative braking by a motor is executed in a state where the engine and the axle (drive shaft) are directly connected. For this reason, the rotational speed of the engine that is in the combustion operation cannot be quickly reduced, and the fuel consumption of the engine cannot be sufficiently reduced. When the vehicle is decelerated in a situation where fuel cut is prohibited as described above, the vehicle speed gradually decreases according to a required deceleration based on, for example, an accelerator pedal operation amount or an operation speed. Therefore, the rotational speed of the engine directly connected to the axle also decreases only slowly. For this reason, fuel is consumed more by the amount of time required to reduce the engine speed.

  The present invention has been conceived by paying attention to the above technical problem, and it is possible to realize appropriate deceleration and improve energy efficiency while suppressing deterioration of the exhaust gas purification catalyst. An object is to provide a simple hybrid vehicle.

  In order to achieve the above object, the present invention relates to an engine, drive wheels, a catalytic converter that purifies the exhaust gas of the engine, and an output shaft of the engine, and outputs torque to output the output shaft. A motor capable of changing the number of rotations (first motor), a braking mechanism for generating a braking force, and a clutch mechanism for selectively interrupting power transmission between the engine and the motor and the drive wheels; A hybrid vehicle that includes a controller that controls the engine, the motor, the braking mechanism, and the clutch mechanism, respectively, and is capable of executing a fuel cut that stops fuel supply to the engine during traveling; The controller should prohibit execution of the fuel cut to suppress degradation of the catalytic converter. When the hybrid vehicle is decelerated in a state where execution of the fuel cut is prohibited, the braking mechanism is controlled to generate the braking force required for the hybrid vehicle, and the clutch mechanism is The power transmission is interrupted to control, and the motor is controlled to reduce the rotation speed of the output shaft.

  Note that the hybrid vehicle of the present invention may include another motor (second motor) that is connected to the drive wheel so that power can be transmitted and generates the braking force by outputting regenerative torque. . In this case, the braking mechanism includes a mechanism for generating the braking force by the other motor, and the controller decelerates the hybrid vehicle in a state where execution of the fuel cut is prohibited. To the regenerative state to generate the braking force required for the hybrid vehicle.

  The hybrid vehicle of the present invention may include an automatic transmission that transmits power between the engine, the motor, and the drive wheels. In that case, the automatic transmission has an engaging element that releases the power transmission between the engine, the motor, and the drive wheel by releasing the automatic transmission to make the automatic transmission neutral. That is, the clutch mechanism includes an engagement element provided in the automatic transmission, and the controller sets the automatic transmission to neutral when decelerating the hybrid vehicle in a state where execution of the fuel cut is prohibited. The power transmission is interrupted by controlling to the state.

  In the hybrid vehicle of the present invention, for the purpose of suppressing the deterioration of the exhaust gas purification catalyst, for example, in a situation where the catalyst temperature at which the catalyst is likely to deteriorate is high, the fuel cut is executed. It is forbidden. Therefore, it is possible to reliably suppress the deterioration of the catalyst. When execution of fuel cut is prohibited, when the hybrid vehicle is decelerated, the braking mechanism is controlled to generate the required braking force. At the same time, power transmission between the engine and the motor and the drive wheels is interrupted, and the rotational speed of the engine is reduced by the regenerative torque of the motor connected to the engine. By controlling the engine speed in a state where power transmission to the drive wheels is interrupted, the engine speed can be quickly reduced. Therefore, compared with the prior art, the amount of fuel consumed by the engine can be reduced by the amount of time required to reduce the engine speed. Therefore, according to the hybrid vehicle of the present invention, it is possible to achieve appropriate deceleration and improve energy efficiency while reliably suppressing deterioration of the catalyst during deceleration traveling.

Configuration of Hybrid Vehicle to be Controlled in the Present Invention and an Example of Control System (Hybrid Vehicle Using Engine and Two Motors as Driving Power Sources, Power Transmission between Engine, First Motor and Drive Wheel FIG. 2 is a diagram showing an example of a four-wheel drive vehicle equipped with a clutch that selectively cuts off a second motor mounted on a drive shaft. Other examples of hybrid vehicles to be controlled in the present invention (equipped with a clutch that selectively cuts off power transmission between the engine and the first motor and the drive wheels, and a second motor that is directly connected to the drive shaft) It is a figure which shows the example of a two-wheel drive vehicle. Other examples of hybrid vehicles to be controlled in the present invention (the clutch that selectively cuts off the power transmission between the engine and the first motor and the drive wheels, and the second motor that is directly connected to the propeller shaft are mounted. It is a figure which shows the example of a two-wheel drive vehicle. FIG. 6 is a diagram showing another example of a hybrid vehicle to be controlled in the present invention (an example of a hybrid vehicle equipped with a brake device that generates a braking force of the vehicle and using an engine and one motor as a driving force source). . Another example of a hybrid vehicle to be controlled in the present invention (an automatic transmission having an engagement element that selectively cuts off power transmission between the engine and the first motor and the drive wheels, and a drive shaft) It is a figure which shows the example of the four-wheel drive vehicle which mounts the 2nd motor to do. Another example of a hybrid vehicle to be controlled in the present invention (equipped with an automatic transmission having an engagement element that selectively cuts off power transmission between the engine and the first motor and the drive wheels (second motor) FIG. 2 is a diagram showing an example of a two-wheel drive vehicle that is not equipped with a vehicle. It is a flowchart for demonstrating an example of the control performed by the controller of the hybrid vehicle of this invention. It is a time chart for demonstrating the behavior of the hybrid vehicle at the time of performing control shown by the flowchart of FIG. It is a flowchart for demonstrating the other example of the control performed by the controller of the hybrid vehicle of this invention. 10 is a time chart for explaining the behavior of the hybrid vehicle when the control shown in the flowchart of FIG. 9 is executed.

  Embodiments of the present invention will be described with reference to the drawings. The embodiment described below is merely an example when the present invention is embodied, and does not limit the present invention.

  The hybrid vehicle to be controlled in the embodiment of the present invention is a hybrid vehicle equipped with an engine and a motor as power sources. At least one motor is coupled to the output shaft of the engine. FIG. 1 shows an example of a hybrid vehicle equipped with an engine and two motors.

  A hybrid vehicle (hereinafter referred to as vehicle) Ve shown in FIG. 1 includes an engine (ENG) 1, a first motor (MG 1) 2, and a second motor (MG 2) 3 as power sources. Further, the vehicle Ve includes a catalytic converter 4, a clutch 5, a detection unit 6, and a controller (ECU) 7 as other main components. In the example shown in FIG. 1, the vehicle Ve uses the first motor 2, the clutch 5, the propeller shaft 8, and the differential gear 9 to drive the drive torque output from the engine 1 through the drive shaft 10 and the drive wheels (FIG. 1). In the example shown in FIG. Further, the second motor 3 is connected to the drive shaft 13 and the drive wheel (front wheel in the example shown in FIG. 1) 14 via the differential gear 12 so that power can be transmitted. Therefore, the vehicle Ve shown in FIG. 1 is a four-wheel drive vehicle that generates drive force by transmitting drive torque output from a power source to both the front wheels (drive wheels 14) and the rear wheels (drive wheels 11).

  The engine 1 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine, and is configured such that output adjustment and operation states such as starting and stopping are electrically controlled. In the case of a gasoline engine, the throttle valve opening, the amount of fuel supplied or injected, and the ignition timing are electrically controlled. In the case of a diesel engine, the fuel injection amount, the fuel injection timing, or the opening degree of a throttle valve in an EGR [Exhaust Gas Recirculation] system is electrically controlled.

  The first motor 2 is, for example, a permanent magnet type synchronous motor or an electric motor such as an induction motor. The first motor 2 mainly functions as a generator that generates (regenerates) electricity by being driven by receiving torque from the outside. The first motor 2 also functions as a prime mover that is driven by power supply and outputs torque (powering). That is, the first motor 2 is a so-called motor / generator having both the function as a generator and the function as a prime mover. The first motor 2 is electrically controlled in output rotation speed and output torque. In addition, switching between the function as a generator and the function as a prime mover is electrically controlled. The first motor 2 is disposed on the output side of the engine 1 and is connected to the output shaft 1a of the engine 1 so that power can be transmitted. Therefore, by regenerating the first motor 2 and outputting a braking torque, it is possible to brake the output shaft 1a of the engine 1 and reduce the rotational speed of the output shaft 1a. Therefore, the first motor 2 corresponds to the “motor” in the embodiment of the present invention.

  The second motor 3 is, for example, a permanent magnet type synchronous motor or an electric motor such as an induction motor, as in the case of the first motor 2 described above. It functions as a prime mover that outputs (powers). The second motor 3 also functions as a generator that generates (regenerates) electricity by being driven by receiving torque from the outside. In other words, the second motor 3 is a so-called motor / generator having both the function as the prime mover and the function as the generator. The second motor 3 is electrically controlled for output rotation speed and output torque. In addition, switching between the function as a prime mover and the function as a generator as described above is electrically controlled. The second motor 3 is connected to the drive shaft 13 and the drive wheels 14 through the differential gear 12 so that torque can be applied. The second motor 3 generates electric power by being driven by receiving torque from the drive wheels 14. That is, the second motor 3 is coupled to the drive wheel 14 so that power can be transmitted. Therefore, by regenerating the second motor 3 and outputting the braking torque, it is possible to brake the drive wheels 14 and generate the braking force of the vehicle Ve. Therefore, the second motor 3 corresponds to the “braking mechanism” in the embodiment of the present invention.

  The “braking mechanism” in the embodiment of the present invention includes a brake device 21 as shown in FIG. Therefore, as the “braking mechanism” in the embodiment of the present invention, the braking mechanism that generates the braking force by regeneratively controlling the second motor 3 as described above and the brake device 21 as shown in FIG. 4 are used in combination. It is also possible.

  The catalytic converter 4 is mounted on an exhaust system (not shown) of the engine 1 and purifies the exhaust gas of the engine 1 with an internal catalyst. For example, in the case of a three-way catalyst, platinum, palladium, and rhodium are mainly used as a catalyst material, and hydrocarbons, carbon monoxide, and Nitrogen oxide is converted into water, carbon dioxide, nitrogen and the like to be detoxified.

  The clutch 5 selectively blocks power transmission between the engine 1 and the first motor 2 and the drive wheels 11. In the example shown in FIG. 1, the clutch 5 is provided between the first motor 2 connected to the output shaft 1 a of the engine 1 and the propeller shaft 8. The clutch 5 enables power transmission between the engine 1 and the first motor 2 and the drive wheels 11 by being engaged. On the other hand, by releasing, the power transmission between the engine 1 and the first motor 2 and the drive wheels 11 is cut off. Therefore, the clutch 5 corresponds to the “clutch mechanism” in the embodiment of the present invention.

  The “clutch mechanism” in the embodiment of the present invention also includes an engagement element 32 provided in the automatic transmission 31 as shown in FIGS. The automatic transmission 31 has at least one engaging element 32 that makes the automatic transmission 31 neutral when released. Accordingly, the engagement element 32 provided in the automatic transmission 31 is controlled to be in the released state, and the automatic transmission 31 is set to neutral, thereby transmitting power between the engine 1 and the first motor 2 and the drive wheels 11. It is possible to block.

  The detector 6 detects or calculates at least the vehicle speed of the vehicle Ve, the operating states of the engine 1, the first motor 2 and the second motor 3, the temperature of the catalytic converter 4, the operating state of the clutch 5, and the like. And equipment. Therefore, the detection unit 6 typically includes a wheel speed sensor 6 a that detects the rotation speed of each wheel, an engine rotation speed sensor 6 b that detects the rotation speed of the output shaft 1 a of the engine 1, and the rotation speed of the first motor 2. A first motor rotation number sensor (or resolver) 6c that detects the rotation of the second motor 3, a second motor rotation number sensor (or resolver) 6d that detects the rotation number of the second motor 3, and a catalyst that detects the temperature of the catalyst of the catalytic converter 4. A temperature sensor 6e and a hydraulic sensor 6f for detecting an engagement hydraulic pressure for controlling the clutch torque capacity (transmission torque capacity) of the clutch 5 are provided. In addition, for example, an accelerator position sensor 6g that detects an operation amount and an operation speed of an accelerator pedal (not shown) by a driver, and a battery that exchanges electric power between the first motor 2 and the second motor 3 ( And an SOC sensor 6h for detecting the amount of charge (not shown) and the state of charge (SOC). In addition, a shift stage (or transmission ratio) set by the automatic transmission 31 and a shift position sensor (not shown) for detecting a neutral state as shown in FIGS. Yes. And the detection part 6 is electrically connected with the controller 7 mentioned later, and outputs the electrical signal according to the detected value or calculated value of the above various sensors, apparatuses, etc. to the controller 7 as detection data.

  The controller 7 is an electronic control unit mainly composed of, for example, a microcomputer. In the example shown in FIG. 1, the engine 1, the first motor 2, the second motor 3, and the clutch 5 are mainly provided. Control. A brake device 21 as shown in FIG. 4 to be described later and an automatic transmission 31 as shown in FIGS. 5 and 6 to be described later are also controlled by the controller 7. Various data detected or calculated by the detection unit 6 are input to the controller 7. The controller 7 performs calculations using the various input data and data or calculation formulas stored in advance. The controller 7 outputs the calculation result as a control command signal, and is configured to control the operation of the engine 1, the first motor 2, the second motor 3, and the clutch 5 as described above. ing. Although FIG. 1 shows an example in which one controller 7 is provided, a plurality of controllers 7 may be provided for each device or device to be controlled, or for each control content.

  The vehicle Ve in the embodiment of the present invention may be a two-wheel drive vehicle that drives either the front wheels or the rear wheels. That is, in the embodiment of the present invention, for example, a two-wheel drive hybrid vehicle having the rear wheels as the drive wheels 11 can be set as a control object, such as the vehicle Ve shown in FIGS. In the example shown in FIG. 2, the second motor 3 is directly connected to the drive shaft 10 of the rear wheel and is connected to the drive wheel 11 so that power can be transmitted. In the example shown in FIG. 3, the second motor 3 is directly connected to the propeller shaft 8 and is connected to the drive wheels 11 via the drive shaft 10 so that power can be transmitted. 2 and 3, parts or members having the same configuration and function as those of the vehicle Ve shown in FIG. 1 are given the same reference numerals as those in FIG.

  The vehicle Ve in the embodiment of the present invention may be a hybrid vehicle using the engine 1 and one motor as a power source. That is, in the embodiment of the present invention, as in the vehicle Ve shown in FIG. 4, a hybrid vehicle that includes the engine 1 and the first motor 2 as power sources and does not include the second motor 3 described above is set as a control target. You can also. In the example illustrated in FIG. 4, the vehicle Ve includes a brake device (BK) 21. The brake device 21 is a device that generates a braking force of the vehicle Ve, and conventionally has a general configuration such as a hydraulic disc brake or a drum brake. In the vehicle Ve in the embodiment of the present invention, the brake device 21 can be automatically controlled by the controller 7 described later. Therefore, the brake device 21 corresponds to the “braking mechanism” in the embodiment of the present invention. In FIG. 4, parts or members having the same configuration and function as those of the vehicle Ve shown in FIG. 1 are given the same reference numerals as those in FIG. 1.

  Further, in the embodiment of the present invention, a hybrid vehicle equipped with an automatic transmission (AT) 31 can be controlled instead of the clutch 5 described above, like a vehicle Ve shown in FIG. In the example shown in FIG. 5, the vehicle Ve is provided with an automatic transmission 31 between the first motor 2 and the propeller shaft 8. The automatic transmission 31 has an engagement element 32 that releases the power transmission between the engine 1 and the first motor 2 and the drive wheels 11 by releasing the automatic transmission 31 to neutral. In other words, the automatic transmission 31 is generally composed of, for example, a planetary gear mechanism (not shown) and an engagement element 32 that is selectively engaged to set a predetermined gear stage (speed ratio). It is a typical stepped transmission. Therefore, the engagement element 32 of the automatic transmission 31 functions as a clutch mechanism that selectively cuts off power transmission between the engine 1 and the first motor 2 and the drive wheels 11. By controlling the operation of the engagement element 32 to make the automatic transmission 31 neutral, the power transmission between the engine 1 and the first motor 2 and the drive wheels 11 can be cut off. Therefore, the engagement element 32 corresponds to the “clutch mechanism” in the embodiment of the present invention. Note that a hybrid vehicle equipped with an automatic transmission 31 instead of the clutch 5 may be a control target for a hybrid vehicle equipped with only one first motor 2 as in the vehicle Ve shown in FIG. it can. 5 and 6 as described above, the same reference numerals as those in FIG. 1 are given to parts or members having the same configuration and function as those of the vehicle Ve shown in FIG.

  As described above, if the vehicle Ve performs fuel cut while the catalyst is at a high temperature, the temperature of the catalyst further increases, and the catalyst may be deteriorated. Therefore, as disclosed in, for example, Patent Document 1 described above, conventionally, in a region where the catalyst is at a high temperature equal to or higher than a predetermined temperature, fuel cut is prohibited in order to suppress the deterioration of the catalyst. When the vehicle travels at a reduced speed in a state where fuel cut is prohibited, for example, in the vehicle disclosed in Patent Document 1 described above, the rotational speed of the engine cannot be quickly reduced during deceleration. That is, as compared with the case where fuel cut is performed, it takes time to reduce the engine speed, and extra fuel is consumed accordingly.

  Accordingly, the control device for the vehicle Ve in the embodiment of the present invention controls the braking mechanism (that is, the second motor 3 or the brake device 21) to control the vehicle Ve when the vehicle Ve is decelerated in a state where fuel cut is prohibited. The braking force required for Ve is generated, and the clutch 5 is controlled to cut off the power transmission between the engine 1 and the first motor 2 and the drive wheels 11, and the first motor 2 is controlled to control the engine 1. Control is performed to reduce the rotational speed of the output shaft 1a. A specific example of such control will be described below.

  FIG. 7 is a flowchart showing an example of the control, and is executed while the vehicle Ve is traveling. In the flowchart of FIG. 7, in step S101, a catalyst deterioration suppression flag is acquired. The catalyst deterioration suppression flag is a flag for determining whether or not catalyst deterioration in the catalytic converter 4 needs to be suppressed. For example, when the catalyst temperature is equal to or higher than a predetermined temperature and it is determined that it is necessary to suppress the deterioration of the catalyst, the catalyst deterioration suppression flag is turned ON. When it is determined that the catalyst temperature is lower than the predetermined temperature and it is not necessary to suppress the deterioration of the catalyst, the catalyst deterioration suppression flag is turned off.

  In step S102, a fuel cut condition satisfaction flag is acquired. The fuel cut condition satisfaction flag is a flag for determining whether or not the fuel cut should be performed, and is turned ON when a predetermined fuel cut execution condition is satisfied. For example, when the vehicle Ve is decelerated, if the accelerator is OFF (accelerator opening is 0) and the engine speed is equal to or higher than a predetermined speed, the fuel cut condition satisfaction flag is turned ON.

  In step S103, it is determined whether there is a request for catalyst deterioration suppression / deceleration. When the catalyst deterioration suppression flag is ON and the fuel cut condition satisfaction flag is ON, it is determined that there is a request for catalyst deterioration suppression / deceleration.

  If a negative determination is made in step S103 because there is no request for catalyst deterioration suppression / deceleration, the present invention is not directly related to the “various control during catalyst deterioration suppression / deceleration” of the embodiment. Therefore, in this case, this routine is temporarily terminated without executing the subsequent control.

  On the other hand, if a positive determination is made in step S103 due to a request for catalyst deterioration suppression / deceleration, the process proceeds to step S104.

  In step S104, a battery charge limit value is acquired. The battery charge limit value is a value mainly determined from the viewpoint of battery protection, and is obtained based on, for example, the charge amount of the battery, the SOC, the temperature, and the like.

  In step S105, it is determined whether or not the battery charge limit value is less than zero. Specifically, it is determined whether or not the battery charge limit value is smaller than a predetermined reference value. In other words, it is determined whether or not it is possible to charge the battery with electric power corresponding to a certain amount of work.

  If the battery charge limit value is less than 0 and the determination in step S105 is affirmative, the process proceeds to step S106.

  In step S106, the clutch release request flag at the time of catalyst deterioration suppression / deceleration is turned ON. The clutch release request flag is a request value for an actuator (not shown) that operates the clutch 5, and is turned ON when the battery charge limit value is less than 0 as described above, and the battery charge limit value Is turned off when is greater than or equal to zero.

  Accordingly, if the battery charge limit value is 0 or more and a negative determination is made in step S105, the process proceeds to step S107, and the clutch release request flag during catalyst deterioration suppression / deceleration is turned OFF.

  As shown in FIG. 6 described above, when the vehicle Ve equipped with the automatic transmission 31 instead of the clutch 5 is to be controlled, when the clutch release request flag is ON, the automatic transmission 31 is neutral. To be.

  In step S108, the engine required torque for the engine 1 is calculated. The engine required torque is a required value for an actuator (not shown) for operating the engine 1, and is set to, for example, a torque in a state where the engine 1 is operated with a minimum load in a range where the engine 1 does not stop.

  In step S109, the value of the engine required torque at the time of catalyst deterioration suppression / deceleration is updated. Specifically, the engine required torque calculated in step S108 is updated as the latest value.

  In step S110, the current engine speed (the speed of the output shaft 1a) is acquired. As described above, the current engine speed can be obtained based on the detected value of the engine speed sensor 6b.

  In step S111, the current engine torque is acquired. The engine torque in this case is an estimated value, and is calculated based on, for example, the engine speed, load factor, ignition timing, intake pipe pressure, engine water temperature, and the like.

  In step S112, the target engine speed is calculated. The target engine speed is a target value for quickly reducing the speed of the engine 1 in a situation where catalyst deterioration is suppressed and decelerated. The target engine speed is set in advance in consideration of, for example, fuel consumption of the engine 1 and vibration / noise.

  In step S113, it is determined whether the engine speed does not undershoot. Based on the engine rotational speed, engine torque, target engine rotational speed, and the like obtained in the above steps, the possibility of undershooting when the rotational speed of the engine 1 is reduced is estimated.

Specifically, it is determined whether or not the base value of the engine regeneration torque is larger than the lower limit value of the engine regeneration torque. When the base value of the engine regeneration torque is larger than the lower limit value, it is estimated that the engine speed does not undershoot. When the base value of the engine regenerative torque is less than or equal to the lower limit value, the engine speed is estimated to be undershoot. The base value of the engine regenerative torque is a value that determines the rate of decrease when the engine speed is decreased at a constant engine torque. For example, the base value of the engine regenerative torque is set in advance in consideration of the fuel consumption of the engine 1 and vibration / noise. . The lower limit of the engine regenerative torque, for example, the current engine torque T _e, the inertia of the engine 1 I, after a predetermined time has elapsed from the current angular acceleration for realizing the target engine rotational speed and omega,
Lower limit _{= I × dω / dt-T} e
It can be calculated from the following formula.

  If it is determined in step S113 that the engine speed is estimated not to undershoot, the process proceeds to step S114.

  In step S114, the target MG1 torque is set to the base value of the engine regeneration torque as described above. The target MG1 torque in this case is a target value for the regenerative torque output by the first motor 2. The controller 7 according to the embodiment of the present invention releases the clutch 5 and cuts off the power transmission between the engine 1 and the first motor 2 and the drive wheels 11 in the above-described situation of the catalyst deterioration suppression / deceleration. At the same time, the first motor 2 is controlled to be in a regenerative state to reduce the rotational speed of the output shaft 1a of the engine 1. The target MG1 torque is a target value when the engine speed is reduced by the regenerative torque of the first motor 2 as described above.

  If it is determined negative in step S113 because the engine speed is estimated to undershoot, the process proceeds to step S115.

  In step S115, the target MG1 torque is set to the lower limit value of the engine regeneration torque as described above. By doing so, it is possible to suppress undershoot when the engine speed is reduced, and it is possible to suppress excessive fuel consumption of the engine 1.

In step S116, the MG1 required power is calculated. The MG1 required power is calculated based on the target engine speed calculated in step S112 and the target MG1 torque set in step S114 or step S115. Specifically, if the target engine speed is N _e and the target MG1 torque is Tt _MG1 ,
MG1 required power = N _e × Tt _MG1
It can be calculated from the following formula.

  In step S117, it is determined whether the first motor 2 can regenerate the MG1 required power. Specifically, it is determined whether or not the MG1 required power calculated in step S116 is equal to or less than the battery charge limit value acquired in step S104. When the MG1 required power is equal to or less than the battery charge limit value, it is determined that the MG1 required power can be regenerated by the first motor 2. When the MG1 required power exceeds the battery charge limit value, it is determined that the MG1 required power cannot be regenerated by the first motor 2.

  If it is determined in step S117 that the MG1 required power cannot be regenerated by the first motor 2, the process proceeds to step S118.

  In step S118, the MG1 required power is set to the battery charge limit value acquired in step S104. That is, the MG1 required power is set to an upper limit value that enables the first motor 2 to regenerate the MG1 required power.

  If it is possible to regenerate the MG1 required power by the first motor 2, and if a positive determination is made in step S117, the process proceeds to step S119.

  In step S119, the value of the MG1 required power during catalyst deterioration suppression / deceleration is updated. Specifically, the MG1 required power calculated in the above step S116 or the MG1 required power set in the above step S118 is updated as the latest value.

  In step S120, the required driving force of the vehicle Ve is acquired. The required driving force is obtained from a map set in advance based on the vehicle speed and the accelerator opening (or the accelerator position), for example.

  In step S121, the target MG2 torque is calculated. The target MG2 torque in this case is a target value for the regenerative torque output by the second motor 3. As described above, in the vehicle Ve according to the embodiment of the present invention, the second motor 3 is regenerated to output a braking torque, thereby braking the driving wheel 14 or the driving wheel 11 to generate the braking force of the vehicle Ve. . The controller 7 according to the embodiment of the present invention releases the clutch 5 and cuts off the power transmission between the engine 1 and the first motor 2 and the drive wheels 11 in the above-described situation of the catalyst deterioration suppression / deceleration. At the same time, the first motor 2 is controlled to be in a regenerative state to reduce the rotational speed of the output shaft 1a of the engine 1. Further, the braking mechanism (that is, the second motor 3 or the brake device 21) is controlled to generate the braking force required for the vehicle Ve. The target MG2 torque is a target value when the braking force is generated by the regenerative torque of the second motor 3 as described above.

For example, in the vehicle Ve shown in FIG. 1, the target MG2 torque is set such that the required driving force obtained in step S120 is F, the reduction gear ratio of the differential gear 12 is R _diff2 , and the tire radius of the driving wheel 14 is r. Then
Target MG2 torque = F ÷ R _diff2 ÷ r
It can be calculated from the following formula.

  In step S122, the target MG2 rotational speed is calculated. The target MG2 rotational speed in this case is a target value when the braking force of the vehicle Ve is generated by the regenerative torque of the second motor 3.

In step S123, the MG2 required power is calculated. The MG2 required power is calculated based on the target MG2 rotational speed calculated in step S122 and the target MG2 torque calculated in step S121. Specifically, if the target MG2 rotational speed is Nt _MG2 and the target MG2 torque is Tt _MG2 ,
MG2 required power = Nt _MG2 × Tt _MG2
It can be calculated from the following formula.

  In step S124, it is determined whether or not the MG2 required power can be regenerated by the second motor 3. Specifically, it is determined whether or not the MG2 required power calculated in step S123 is equal to or less than the battery charge limit value acquired in step S104. When the MG2 required power is equal to or less than the battery charge limit value, it is determined that the MG2 required power can be regenerated by the second motor 3. When the MG2 required power exceeds the battery charge limit value, it is determined that the MG2 required power cannot be regenerated by the second motor 3.

  If it is determined in step S124 that the MG2 required power cannot be regenerated by the second motor 3, the process proceeds to step S125.

  In step S125, the MG2 required power is set to the difference between the battery charge limit value acquired in step S104 and the MG1 required power updated in step S119. That is, the MG2 required power is set to an upper limit value that enables the second motor 3 to regenerate the MG2 required power.

  If the second motor 3 can regenerate the MG2 required power, and if the determination in step S124 is affirmative, the process proceeds to step S126.

  In step S126, the value of the MG2 required power at the time of catalyst deterioration suppression / deceleration is updated. Specifically, the MG2 required power calculated in the above step S123 or the MG2 required power set in the above step S125 is updated as the latest value.

In step S127, the required braking force is calculated. This is the braking force required for the vehicle Ve according to the operation of the driver. Specifically, the required driving force is F, the engine torque is T _e , the torque of the first motor 2 is T _MG1 , the reduction ratio of the differential gear 9 is R _diff1 , the torque of the second motor 3 is T _MG2 , and the differential gear 12. If the reduction ratio of R is _diff2 ,
Necessary braking force _{= F - {(T e +} T MG1) × R diff1 + T MG2 × R diff2}
It can be calculated from the following formula.

  In step S128, the value of the braking request torque at the time of catalyst deterioration suppression / deceleration is updated. Specifically, the braking torque corresponding to the necessary braking force calculated in step S127 is updated as the latest value.

  In step S129, the release control of the clutch 5 (or the shift control that makes the automatic transmission 31 neutral), the engine speed reduction control by the first motor 2, and the second motor 3 (or the brake device 21). ) Is executed. For example, the clutch 5 is released (or the automatic transmission 31 is made neutral) based on the required value for the actuator of the clutch 5 described above. Further, based on the MG1 required power updated and set in step S119, the engine speed is quickly reduced by the regenerative torque of the first motor 2. Further, the vehicle Ve is braked by the regenerative torque of the second motor 3 based on the MG2 required power updated and set in step S126 and the braking request torque updated and set in step S128. Alternatively, the vehicle Ve is braked by the brake device 21).

  The release control of the clutch 5, the engine speed reduction control by the first motor 2, and the braking control by the second motor 3 are appropriately executed in cooperation with each other or in order. Thereafter, this routine is once terminated.

  The behavior of the vehicle Ve when the control shown in the flowchart of FIG. 7 is executed as described above is shown in the time chart of FIG. The time chart of FIG. 8 shows a situation in which the vehicle Ve decelerates in a state where fuel cut is prohibited due to, for example, a high catalyst temperature. When the depression of the accelerator pedal is returned at time t1, thereafter, the vehicle speed gradually decreases according to the requested deceleration.

  In the control at the time of catalyst deterioration suppression / deceleration in the embodiment of the present invention, in order to achieve the required deceleration, the second motor 3 is controlled as a braking mechanism to generate a regenerative torque (braking torque). At the same time, the clutch 5 is released to interrupt the power transmission between the engine 1 and the first motor 2 and the drive wheels 11. Further, the second motor 3 is controlled to be in a regenerative state, and the engine speed is quickly reduced. In this case, the engine rotational speed is reduced to the idling rotational speed of the engine 1 or a rotational speed corresponding thereto. As the engine speed decreases, the engine torque decreases to zero or nearly zero. That is, the engine 1 is controlled to a minimum engine torque that does not stop the combustion operation.

  As indicated by the broken line in the time chart of FIG. 8, in the conventional control, the engine speed cannot be quickly reduced during catalyst deterioration suppression / deceleration. In other words, in the conventional control, the engine speed decreases only gradually as the vehicle speed decreases. On the other hand, in the control during catalyst deterioration suppression / deceleration in the embodiment of the present invention, as described above, the engine speed can be quickly reduced during deceleration. Therefore, as shown by hatching in the time chart of FIG. 8, the fuel consumption of the engine 1 can be suppressed as compared with the conventional control.

  The controller 7 according to the embodiment of the present invention controls the vehicle Ve equipped with the automatic transmission 31 as shown in FIGS. 5 and 6 described above, for example, the flowchart of FIG. 9 and FIG. It is also possible to execute the control shown in the time chart.

  In the flowchart of FIG. 9, in step S201, a catalyst deterioration suppression flag is acquired. As in step S101 in the flowchart of FIG. 7, the catalyst deterioration suppression flag is a flag for determining whether or not it is necessary to suppress catalyst deterioration in the catalytic converter 4.

  In step S202, a fuel cut condition satisfaction flag is acquired. As in step S102 in the flowchart of FIG. 7, the fuel cut condition satisfaction flag is a flag for determining whether or not to perform fuel cut.

  In step S203, it is determined whether there is a request for catalyst deterioration suppression / deceleration. When the catalyst deterioration suppression flag is ON and the fuel cut condition satisfaction flag is ON, it is determined that there is a request for catalyst deterioration suppression / deceleration.

  If a negative determination is made in step S203 because there is no request for catalyst deterioration suppression / deceleration, the present invention is not directly related to the “various controls during catalyst deterioration suppression / deceleration” of the embodiment. Therefore, in this case, this routine is temporarily terminated without executing the subsequent control.

  On the other hand, if a positive determination is made in step S203 due to a request for catalyst deterioration suppression / deceleration, the process proceeds to step S404.

  In step S204, the current vehicle speed and the gear stage (shift stage) set in the automatic transmission 31 are acquired. As described above, the current vehicle speed and the gear position of the automatic transmission 31 can be obtained based on the detection value of the wheel speed sensor 6a and the detection value of the shift position sensor.

  In step S205, the required gear stage for the automatic transmission 31 is calculated. Specifically, at the current vehicle speed detected in the above step S204, the highest gear stage (the gear stage at which the gear ratio is the minimum) at which the engine speed is equal to or higher than a predetermined speed is obtained.

  In step S206, the required gear stage during catalyst deterioration suppression / deceleration is updated. The required gear is a required value for an actuator (not shown) that operates the automatic transmission 31, and the required gear calculated in step S207 is updated as the latest value.

  In step S207, the engine required torque for the engine 1 is calculated. The engine required torque is a required value for an actuator (not shown) for operating the engine 1, and is set to, for example, a torque in a state where the engine 1 is operated with a minimum load within a range where the engine 1 does not stop.

  In step S208, the value of the engine required torque at the time of catalyst deterioration suppression / deceleration is updated. Specifically, the engine required torque calculated in step S207 is updated as the latest value.

  In step S209, the current engine speed (the speed of the output shaft 1a) is acquired. As described above, the current engine speed can be obtained based on the detected value of the engine speed sensor 6b.

  In step S210, the current engine torque is acquired. The engine torque in this case is an estimated value, and is calculated based on, for example, the engine speed, load factor, ignition timing, intake pipe pressure, engine water temperature, and the like.

  In step S211, the required driving force of the vehicle Ve is acquired. The required driving force is obtained from a map set in advance based on the vehicle speed and the accelerator opening (or the accelerator position), for example.

  In step S212, the target MG1 torque is calculated. The target MG1 torque in this case is a target value for the regenerative torque output by the first motor 2. In the control example shown in the flowchart of FIG. 9, the first motor 2 is regenerated and braking torque is output, thereby braking the drive wheels 11 to generate the braking force of the vehicle Ve. At the same time, the controller 7 upshifts the automatic transmission 31 in the above-described situation in which the catalyst deterioration is suppressed and decelerated, that is, the gear ratio of the automatic transmission 31 is reduced to reduce the output shaft 1a of the engine 1. Reduce the number of revolutions. The target MG1 torque is a target value when the braking force is generated by the regenerative torque of the first motor 2 as described above.

  In step S213, the MG1 required power is calculated. The MG1 required power in this case is calculated based on the target engine speed and the target MG1 torque calculated in step S212 described above.

  In step S214, the battery charge limit value is acquired. The battery charge limit value is a value mainly determined from the viewpoint of battery protection, and is obtained based on, for example, the charge amount of the battery, the SOC, the temperature, and the like.

  In step S215, it is determined whether or not the MG1 required power can be regenerated by the first motor 2. Specifically, it is determined whether the MG1 required power calculated in step S213 is less than or equal to the battery charge limit value acquired in step S214. When the MG1 required power is equal to or less than the battery charge limit value, it is determined that the MG1 required power can be regenerated by the first motor 2. When the MG1 required power exceeds the battery charge limit value, it is determined that the MG1 required power cannot be regenerated by the first motor 2.

  If it is determined in step S215 that the MG1 required power cannot be regenerated by the first motor 2, the process proceeds to step S216.

  In step S216, the MG1 required power is set to the battery charge limit value acquired in step S214. That is, the MG1 required power is set to an upper limit value that enables the first motor 2 to regenerate the MG1 required power.

  If it is possible to regenerate the MG1 required power by the first motor 2, and if a positive determination is made in step S215, the process proceeds to step S217.

  In step S217, the value of the MG1 required power during catalyst deterioration suppression / deceleration is updated. Specifically, the MG1 required power calculated in step S213 described above or the MG1 required power set in step S216 described above is updated as the latest value.

  In step S218, the required braking force is calculated. This is the braking force required for the vehicle Ve according to the operation of the driver.

  In step S219, the value of the braking request torque at the time of catalyst deterioration suppression / deceleration is updated. Specifically, the braking torque corresponding to the necessary braking force calculated in step S218 is updated as the latest value.

  In step S220, automatic transmission 31 shift control (upshift) and braking control by the first motor 2 (or brake device 21) are executed.

  The automatic transmission 31 shift control and the braking control by the first motor 2 are appropriately executed in cooperation with each other or in order. Thereafter, this routine is once terminated.

  The behavior of the vehicle Ve when the control shown in the flowchart of FIG. 9 is executed as described above is shown in the time chart of FIG. The time chart of FIG. 10 shows a situation in which the vehicle Ve decelerates in a state where the fuel cut is prohibited due to, for example, the temperature of the catalyst being high. When the depression of the accelerator pedal is returned at time t11, thereafter, the vehicle speed gradually decreases according to the required deceleration.

  In the control example shown in FIG. 10, in order to realize the required deceleration, the first motor 2 is controlled to be in a regenerative state to generate regenerative torque (braking torque). At the same time, the automatic transmission 31 is upshifted to quickly reduce the engine speed. In this case, the engine rotational speed is reduced to the idling rotational speed of the engine 1 or a rotational speed corresponding thereto. The engine 1 is controlled to a minimum engine torque that does not stop the combustion operation.

  As indicated by the broken line in the time chart of FIG. 10, in the conventional control, the engine speed cannot be quickly reduced when the catalyst deterioration is suppressed / decelerated. In other words, in the conventional control, the engine speed decreases only gradually as the vehicle speed decreases. On the other hand, in the control shown in FIG. 10, as described above, the engine speed can be quickly reduced during deceleration. Therefore, as shown by hatching in the time chart of FIG. 10, the fuel consumption of the engine 1 can be suppressed as compared with the conventional control.

  DESCRIPTION OF SYMBOLS 1 ... Engine (ENG), 1a ... (Engine) output shaft, 2 ... 1st motor (MG1: Motor), 3 ... 2nd motor (MG2: Braking mechanism), 4 ... Catalytic converter, 5 ... Clutch (Clutch mechanism) ), 6 ... detector, 6a ... wheel speed sensor, 6b ... engine speed sensor, 6c ... first motor speed sensor (resolver), 6d ... second motor speed sensor (resolver), 6e ... catalyst temperature sensor, 6f ... Hydraulic pressure sensor, 6g ... Accelerator position sensor, 6h ... SOC sensor, 7 ... Controller (ECU), 8 ... Propeller shaft, 9, 12 ... Differential gear, 10, 13 ... Drive shaft, 11, 14 ... Drive wheel, 21 ... Brake device (BK: Braking mechanism), 31 ... Automatic transmission (AT), 32 ... (Automatic transmission) engaging element (clutch mechanism), Ve ... Both (hybrid vehicle).

Claims (1)

An engine, drive wheels, a catalytic converter that purifies the exhaust gas of the engine, a motor that is connected to the output shaft of the engine and that can change the rotational speed of the output shaft by outputting torque; A brake mechanism for generating power, a clutch mechanism for selectively interrupting power transmission between the engine and the motor and the drive wheel, the engine, the motor, the brake mechanism, and the clutch mechanism; A hybrid vehicle including a controller for controlling, and capable of executing fuel cut for stopping fuel supply to the engine during traveling,
The controller is
Determining whether to prohibit execution of the fuel cut to suppress degradation of the catalytic converter;
When decelerating the hybrid vehicle in a state where execution of the fuel cut is prohibited,
Controlling the braking mechanism to generate the braking force required for the hybrid vehicle;
Controlling the clutch mechanism to cut off the power transmission;
A hybrid vehicle, wherein the motor is controlled to reduce the rotational speed of the output shaft.

Images