JP2009113670A - Drive control device for hybrid car - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately switch speed change control giving priority to fuel costs and speed change control giving priority to driveability according to circumstances in a hybrid car in a multi-mode in which speed change is performed via a fixed gear mode. <P>SOLUTION: In the drive control device of a hybrid car, an engine and a motor generator are connected through a power distribution mechanism to an output shaft, and a transmission mechanism is arranged between the power distribution mechanism and an output shaft. A speed change control means selectively executes fuel cost priority speed change control for performing speed change by giving priority to power transmission efficiency and driveability priority speed change control for performing speed change when a gear ratio becomes within a prescribed allowable fluctuation width according to a request power. On the structure of the transmission mechanism, a fixed stage mode in which a plurality of output stages are temporarily connected to an output shaft at the same time is generated in speed change, and the number of revolution of the engine fluctuates in the fixed stage mode in the fuel cost priority shift control. Then, it is possible to improve fuel costs while preventing the deterioration in driveability by selectively executing two speed change control according to the request power. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive control device for a hybrid vehicle including a transmission.

  Hybrid vehicles that include a power source such as an electric motor or a motor generator in addition to an internal combustion engine are known. In a hybrid vehicle, an internal combustion engine is operated in a highly efficient state as much as possible, while an excess or deficiency of driving force or engine braking force is compensated by an electric motor or a motor generator. In such a hybrid vehicle, an internal combustion engine (engine) and a motor generator are connected to an output shaft via a power distribution mechanism having a differential action, and the rotational speed of the motor generator is continuously changed. Thus, the operation in the so-called continuously variable transmission mode is possible.

  In addition, there has been proposed a system that can maintain high transmission efficiency in a wide gear range by combining a synchronous transmission with the hybrid vehicle as described above (see Patent Document 1).

JP-A-2005-155891

  In the hybrid vehicle as described above, only sequential shift including simultaneous fixed stages is possible. For example, when shifting from the first speed to the second speed, it is necessary to go through a fixed stage mode in which the output shaft is fixed to the first and second gears. Therefore, when the shift is performed with priority on fuel efficiency, the gear ratio changes before and after the shift via the fixed speed mode, and the engine speed changes instantaneously.

  As a result, drivability may be reduced. Further, in a state where the catalyst is not sufficiently warmed, such as when the internal combustion engine is cold-started, if the fluctuation of the engine speed is large, the air-fuel ratio fluctuates, and there is a concern about emission deterioration or misfire. Further, since the engine speed is controlled by the motor generator at the time of shifting, the fluctuation of the engine speed as described above needs to be controlled by the motor generator. Therefore, depending on the temperature of the battery and the state of charge, the response by the motor generator may be delayed or insufficient, which may cause a delay in shifting or disable shifting.

  The present invention has been made to solve the above-described problems, and in a multi-mode hybrid vehicle in which a shift is performed via a fixed stage mode, a shift control with priority on fuel consumption and a shift control with priority on drivability. The purpose is to switch appropriately according to the situation.

  In one aspect of the present invention, a hybrid vehicle drive control device in which an engine and a motor generator are connected to an output shaft via a power distribution mechanism is provided between the power distribution mechanism and the output shaft, A speed change mechanism that performs a shift through a plurality of continuously variable speed stages, and a speed change control that performs a shift via a fixed speed mode in which a speed ratio is fixed by connecting a plurality of speed change gears of the continuously variable speed stages to an output shaft. A first shift control that shifts with priority given to power transmission efficiency, and a second shift that shifts when the gear ratio falls within a predetermined allowable gear ratio fluctuation range. The shift control is selectively executed according to the required power.

  In the hybrid vehicle driving apparatus, an engine and a motor generator are coupled to an output shaft via a power distribution mechanism. As a result, the engine is operated in the most efficient operating state, and the output torque of the engine is stored as electric energy by the motor generator, or the electric energy is converted into driving torque and supplied to the output shaft for assistance. As a whole, efficient operation is performed. A speed change mechanism is provided between the power distribution mechanism and the output shaft, and a speed change is performed over a plurality of speed stages such as the first speed to the fourth speed, for example. The speed change operation by the speed change mechanism is performed by the speed change control means. Here, the shift control means performs a first shift control that shifts with priority given to power transmission efficiency according to the required power, and a second shift that shifts when the gear ratio falls within a predetermined allowable fluctuation range. The shift control is selectively executed. Due to the structure of the speed change mechanism, a fixed speed mode in which a plurality of output speeds are simultaneously connected to the output shaft at the time of speed change occurs. In the first shift control that prioritizes power transmission efficiency, the engine speed fluctuates in the fixed speed mode, which causes a deterioration in drivability. On the other hand, in the second shift control that shifts when the gear ratio falls within a predetermined allowable fluctuation range, the engine speed fluctuates very little, but the gear is shifted at a point where the power transmission efficiency is low. The cost for improvement is reduced. Therefore, by selectively executing the first shift control and the second shift control according to the required power, it is possible to perform driving with as much fuel consumption as possible while preventing a decrease in drivability. It becomes.

  In one aspect of the above hybrid vehicle drive control device, the shift control means is configured such that, during execution of the first shift control, the fluctuation range of the engine speed at the time of the shift is equal to or larger than a predetermined allowable engine speed fluctuation range. In this case, the second shift control is performed. In the first shift control, the shift is basically performed with priority on fuel consumption. However, if the fluctuation of the engine speed at the shift is equal to or larger than the allowable fluctuation range, the second shift control is performed from the viewpoint of preventing a decrease in drivability. Switch to shift control. Thereby, both fuel consumption and drivability can be achieved within a certain allowable range.

  In another mode of the above hybrid vehicle drive control device, the shift control means changes the gear ratio allowable fluctuation range in accordance with the required power. In the second shift control, if the allowable fluctuation range of the gear ratio is widened, the fluctuation of the engine speed increases, but the fuel consumption is improved. On the other hand, if the allowable fluctuation range of the gear ratio is narrowed, the fluctuation of the engine speed is reduced, but improvement in fuel consumption cannot be expected. Therefore, in this aspect, by changing the allowable fluctuation range of the gear ratio according to the power required by the user, the fuel consumption is improved within the range of the user's tolerance for the engine speed fluctuation.

  In another aspect of the drive control apparatus for a hybrid vehicle described above, there is provided catalyst activity determining means for determining the activity of a catalyst provided in the exhaust passage of the engine, wherein the shift control means is configured such that the catalyst is in an inactive state. If there is, the second shift control is selected. The catalyst provided in the exhaust passage of the engine cannot exhibit normal exhaust purification performance unless it is in an active state in which warming is completed. When the catalyst is in an inactive state, problems such as deterioration of exhaust emission may occur due to the fluctuation of the air-fuel ratio if the fluctuation of the engine speed is large at the time of shifting. Therefore, when the catalyst is in an inactive state, the second shift control with a small fluctuation in the engine speed is executed to prevent the deterioration of the emission. In a preferred example, the speed change control means fixes the speed change mechanism at a predetermined speed when the catalyst is in an inactive state. As a result, the shift is not performed in the inactive state of the catalyst, so that it is possible to reliably prevent the deterioration of the emission due to the fluctuation of the engine speed.

  In another aspect of the drive control apparatus for a hybrid vehicle described above, a charge / discharge limit amount detection unit for detecting a charge / discharge limit amount of a battery connected to the motor generator is provided, and the shift control unit includes the charge / discharge limit unit. When the amount is not less than the first predetermined limit amount, the second shift control is selected. In the first shift control that prioritizes fuel consumption, when fluctuations in engine speed occur, the fluctuations are controlled by the operation of the motor generator, but the operation of the motor generator is accompanied by charging / discharging of the battery. Therefore, in a state where charging / discharging of the battery is limited, it is preferable not to cause fluctuations in the engine speed. Therefore, when the charge / discharge limit amount of the battery is equal to or greater than the predetermined limit amount, the second shift control is performed in which the fluctuation of the engine speed is small.

  In a preferred example in this case, the shift control means fixes the shift mechanism at a predetermined shift stage when the charge / discharge limit amount is equal to or greater than a second predetermined limit amount. In this way, by prohibiting the shift, fluctuations in the engine speed can be prevented, and the burden on the battery can be eliminated. In another preferred example, the shift control means changes the gear ratio allowable fluctuation range based on the charge / discharge limit amount. Thus, the allowable fluctuation range of the gear ratio in the second shift control is set so that the fluctuation of the engine speed becomes small when the charge / discharge limit of the battery is large, and a certain amount of engine speed when the battery charge / discharge limit is small. The fuel consumption can be improved by allowing the fluctuation.

  Preferred embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of a drive control apparatus for a hybrid vehicle according to the present invention. In the example of FIG. 1, the hybrid vehicle includes an internal combustion engine (engine) 1, a first motor generator (MG 1) 2, and a second motor generator (MG 2) 3 as a power unit. The output torque of the engine 1 is distributed to the first motor generator 2 and the output shaft by the power distribution mechanism 4, and the drive torque and brake force are assisted (assisted) by the second motor generator 3. This configuration is called a mechanically distributed two-motor hybrid device.

  The engine 1 is a heat engine that generates power by burning fuel, and examples thereof include a gasoline engine and a diesel engine. The first motor generator 2 generates power mainly by receiving torque from the engine 1 and rotating, and reaction force torque accompanying power generation acts.

  The second motor generator 3 assists the driving torque or the braking force. When assisting the drive torque, the second motor generator 3 functions as an electric motor upon receipt of electric power. On the other hand, when assisting the braking force, the second motor generator 3 functions as a generator that is rotated by torque transmitted from drive wheels (not shown) to generate electric power.

  The power distribution mechanism 4 is configured by substantially combining two sets of planetary gear mechanisms, and in the example shown in FIG. A gear mechanism is used. Specifically, the first sun gear 5 and the ring gear 6 are disposed between the first sun gear 5 that is an external gear and the ring gear 6 that is an internal gear disposed concentrically with the first sun gear 5. A long pinion 7 meshing with each other is arranged. The first sun gear 5, the ring gear 6, and the long pinion 7 constitute a single pinion type planetary gear mechanism. A second sun gear 8 is disposed on the same axis line adjacent to the first sun gear 5, and a short pinion 9 meshing with the second sun gear 8 is meshed with the long pinion 7. Therefore, a double pinion type planetary gear mechanism is configured by the four members of the second sun gear 8, the pinions 9 and 7, and the ring gear 6. A plurality of pairs of long pinions 7 and short pinions 9 meshing with each other are provided, and these pinions 7 and 9 are held by a carrier 10 so as to rotate and revolve.

  Torque is input from the engine 1 to the ring gear 6 in the power distribution mechanism 4. Therefore, the ring gear 6 is an input element of the present invention. 1 shows a configuration in which the engine 1 is directly connected to the ring gear 6, a torque converter and a starting clutch (not shown) are provided between the engine 1 and the ring gear 6, respectively. May be.

  Torque is transmitted from the first motor generator 2 to the first sun gear 5 in the power distribution mechanism 4. Therefore, the first sun gear 5 is a reaction force element. Specifically, a reaction force shaft 11 is arranged on the same axis as the engine 1, and the end of the reaction force shaft 11 opposite to the engine 1 side is connected to the first motor generator via the gear pair 12. It is connected to two rotors. The stator of the first motor generator 2 is connected and fixed to a fixed part such as the casing 13.

  In the power distribution mechanism 4 described above, four elements of the ring gear 6 serving as an input element, the first sun gear 5 serving as a reaction force element, the second sun gear 8 and the carrier 10 are used as rotating elements. The second sun gear 8 and the carrier 10 are selectively used as output elements. The ring gear 6, the first sun gear 5 or the second sun gear 8, and the carrier 10 are configured to generate a differential action.

  A synchronous coupling mechanism is provided between these output elements and the output member for selectively transmitting torque between them. Specifically, first and second intermediate shafts 14 and 15 that are hollow shafts are rotatably fitted to the outer peripheral side of the reaction force shaft 11. The second intermediate shaft 15 on the outer peripheral side is connected to the carrier 10, and the first intermediate shaft 14 on the inner peripheral side is connected to the second sun gear 8 and at the tip side of the second intermediate shaft 15 (opposite to the engine 1). Protruding to the side).

  An output shaft 16 is rotatably arranged parallel to the intermediate shafts 14 and 15 at a predetermined distance from the intermediate shafts 14 and 15. A first speed gear pair 17 and a third speed gear pair 18 are arranged between the first intermediate shaft 14 and the output shaft 16. The gear pairs 17 and 18 are disposed adjacent to each other in the axial direction. Further, a second speed gear pair 19 and a fourth speed gear pair 20 are disposed between the second intermediate shaft 15 and the output shaft 16. The gear pairs 19 and 20 are disposed adjacent to each other in the axial direction.

  Each of the gear pairs 17 to 20 includes a drive gear on the intermediate shafts 14 and 15 side and a driven gear on the output shaft 16 side that is always meshed with the drive gears. The driven gear on the output shaft 16 side of each gear pair 17 and 18 is connected to the clutch mechanism 21. Further, the driven gear on the output shaft 16 side of each gear pair 19, 20 is connected to the clutch mechanism 22. The clutch mechanisms 21 and 22 are configured as dog clutches that engage dog teeth arranged to face each other, and constitute a speed change mechanism in the present invention. Specifically, in the clutch mechanism 21, by moving the actuator 31 to the left in the figure, the output shaft 16 engages with the driven gear of the first speed gear pair 17, and the actuator 31 moves to the right in the figure. As a result, the output shaft 16 engages with the driven gear of the third speed gear pair 18. Similarly, in the clutch mechanism 22, when the actuator 32 is moved in the left direction in the figure, the output shaft 16 is engaged with the driven gear of the second speed gear pair 19, and the actuator 32 is moved in the right direction in the figure. Thus, the output shaft 16 engages with the driven gear of the fourth speed gear pair 20. As described above, by driving the actuators 31 and 32, any one of the first to fourth speeds can be selected. Such drive control of the actuators 31 and 32 is executed by an ECU (not shown).

  In the above configuration, when any one of the first speed to the fourth speed is selected by the speed change mechanism, the drive control apparatus operates in the continuously variable speed mode. That is, when the rotational speed of the first motor generator 2 is continuously changed by the power distribution mechanism 4, the rotational speed of the engine 1 is continuously changed, and the operation in the continuously variable transmission mode is executed. On the other hand, a plurality of gears are always temporarily connected to the output shaft at the time of shifting from the first speed to the second speed and from the second speed to the third speed (hereinafter referred to as “fixed stage mode”). ). For example, in FIG. 1, the clutch mechanism 21 is engaged with the first speed gear pair 17 side during operation at the first speed. At the time of shifting from the first speed to the second speed, first, the actuator 32 is driven leftward in the figure while the clutch mechanism 21 remains unchanged, and the clutch mechanism 22 is engaged with the second speed gear pair 19 side. At this time, the first speed gear pair 17 and the second speed gear pair 19 are temporarily connected to the output shaft 16 at the same time, that is, the fixed stage mode is set. Thereafter, the actuator 31 moves to the right in the figure, the clutch 21 is released, and the output shaft 16 is connected to the second speed gear pair 19 only. Thus, the shift from the first speed to the second speed is performed.

  Thus, in the drive control apparatus of the present embodiment, the fixed stage mode always occurs at the time of shifting. FIG. 2 shows the relationship between the engine speed and the engine torque in the continuously variable transmission mode in which the vehicle is operating at any one of the first to fourth gears and the above-described fixed gear mode. In FIG. 2, a graph 201 shows an operation line in the continuously variable transmission mode, and a graph 202 shows an operation line in the fixed-stage mode. Graph 205 shows thermal efficiency.

  Suppose that the operating point when operating in a continuously variable transmission mode at a certain gear stage (for example, the second speed) is 204, and the operating point when shifting to the fixed gear mode for shifting from there is 203. As shown in the figure, the engine speed and the engine torque fluctuate according to the arrows in the figure at the time of shifting. As described above, in the multi-mode hybrid system as in the present embodiment, the fixed speed mode is always passed through at the time of shifting. Therefore, when shifting is performed with priority on fuel efficiency, the engine speed varies.

  This will be described in detail. FIG. 3A shows the relationship between the gear ratio (gear ratio) and the theoretical transmission efficiency (power transmission efficiency) in the fuel efficiency priority shift control. As shown in the figure, there is a graph showing the relationship between the gear ratio and the theoretical transmission efficiency for each of the first to fourth speeds. Here, in the fuel efficiency priority shift control, a gear stage having a high theoretical transmission efficiency is always used, so that the gear shift is performed according to a graph indicated by a thick line in the figure. However, as described above, the fixed point mode is always passed when shifting, so that the operating point moves only during the fixed step mode. For example, at the time of shifting from the first speed to the second speed, the operating point first moves according to the first speed graph, reaches the point 215, and then once moves to the point 216 in the 1-2 speed fixed state as indicated by the arrow 211. After that, it returns to the point 215 again, and thereafter changes according to the graph of the second speed. Similarly, the operating point moves as indicated by an arrow 212 when shifting from the second speed to the third speed, and the operating point moves as indicated by an arrow 213 when shifting from the third speed to the fourth speed. Therefore, in either case, the speed ratio (gear ratio) fluctuates because the fixed speed mode is temporarily passed during the speed change. Under a condition where the vehicle speed (output) is constant, the change in gear ratio is equivalent to the change in engine speed. Therefore, in the fuel efficiency priority shift control as exemplified in FIG. 3A, the engine speed fluctuates without fail during a shift. The fuel efficiency priority shift control corresponds to the first shift control of the present invention.

  Next, FIG. 3B shows the relationship between the gear ratio and the theoretical transmission efficiency in the drivability priority shift control. In the shift control with priority on drivability, the shift is performed when the gear ratio becomes close to the synchronous rotation speed in the fixed stage mode. In the example of FIG. 3B, in the first speed operation, when the gear ratio corresponding to the 1-2 speed fixed state is reached, as shown by arrows 221 and 222, the fixed speed mode is temporarily passed. After that, the operation shifts to the second speed operation. The operating point moves according to arrows 223 and 224 when shifting from the second speed to the third speed, and according to arrows 225 and 226 when shifting from the third speed to the fourth speed. As described above, in the drivability priority shift control, the theoretical transmission efficiency is lowered during the shift, but the engine speed does not vary because there is no gear ratio variation. The drivability priority shift control corresponds to the second shift control of the present invention.

  As described above, in the drive control device for a multi-mode hybrid vehicle as in the present embodiment, either the fuel efficiency priority shift control or the drivability priority shift control can be selected and performed. Therefore, in the present invention, these two shift controls are selected according to the situation and the shift is executed.

[First embodiment]
The first embodiment of the present invention will be described below. In the first embodiment, from the viewpoint of drivability, fuel efficiency priority shift control and drivability priority shift control are selectively used according to the user's request. For example, when a high load acceleration is requested, such as when accelerating, the engine speed is originally high. Therefore, even if the engine speed fluctuates as described above, the user is often not concerned. Therefore, when the user request such as the vehicle speed or the accelerator opening is a high load acceleration request, the fuel efficiency priority shift control is performed. On the other hand, the engine speed is generally low during a light load steady request such as during steady running where there is little change in vehicle speed or the like, and the user tends to feel a decrease in drivability due to fluctuations in the engine speed. Therefore, when the user request is a low load steady request, the drivability priority shift control is executed. As described above, the drivability priority shift control is a control method in which the shift is performed only when the gear ratio is close to the synchronous rotation speed, and the change in the engine rotation speed before and after the shift can be reduced. In this way, by switching between the fuel efficiency priority shift control and the drivability priority shift control according to the user request, both drivability and fuel efficiency can be achieved.

  Further, when a fuel consumption priority operation mode or the like is selected according to a user request, fuel efficiency priority shift control may be prioritized. This is because the user's tolerance for drivability is considered large when the user himself / herself selects a driving mode that prioritizes fuel consumption. As a result, fuel efficiency priority shift control can be actively implemented even at light loads, and fuel efficiency can be further improved.

  In addition, in the drivability priority shift control, the criterion for determining whether or not the gear ratio is in the vicinity of the synchronous rotation speed may be variable according to the user request power. This will be described in detail with reference to FIG. FIG. 4 shows the relationship between the gear ratio and the theoretical transmission efficiency during drivability priority shift control, as in FIG. Here, in the example of FIG. 3B, the gear is changed when the gear ratio reaches the synchronous rotation speed. For example, the shift from the first speed to the second speed is performed at the gear ratio when the 1-2 speed is fixed. On the other hand, in this example, as shown in FIG. 4, the gear ratio at the time of shifting is given a width. This width is called “gear ratio allowable fluctuation width”. In FIG. 4, when the gear ratio is within the range of the allowable gear ratio fluctuation range determined based on the gear ratio when the first to second speeds are fixed, the shift from the first speed to the second speed is performed. Similarly, in the case of the second speed to the third speed and the third speed to the fourth speed, the range in which the thick line portions of the respective graphs overlap in the vertical direction corresponds to the gear ratio allowable fluctuation range. The gear ratio allowable fluctuation range can be obtained from the engine speed allowable fluctuation range by the following equation.

(Gear ratio allowable fluctuation range)
= (Target engine speed + Engine speed allowable fluctuation range) / (Drive shaft speed)
Next, a method of changing the gear ratio allowable fluctuation range according to the user request power will be described. The allowable gear ratio fluctuation range is equivalent to the allowable fluctuation range of the engine speed under the condition where the vehicle speed is constant. FIG. 5 shows the relationship between the user required power and the allowable engine speed fluctuation range. As indicated by the solid line graph 230, when the user required power is small, the user is sensitive to the engine speed fluctuation, so the engine speed allowable fluctuation width, that is, the gear ratio allowable fluctuation width is reduced. On the other hand, when the user required power is large, the engine speed is originally high and the user is not so sensitive to fluctuations in the engine speed, so the engine speed allowable fluctuation range, that is, the gear ratio allowable fluctuation range is set large. If the engine speed allowable fluctuation range is set to be large, a gear stage (gear) having a high theoretical transmission efficiency can be used within the range, and fuel efficiency can be improved accordingly.

  Specifically, drivability priority shift control is performed when the user requested power is low, but thereafter, the engine speed allowable fluctuation range, that is, the gear ratio allowable fluctuation range is increased as the user required power increases. Then, when the user requested power becomes a predetermined high load, the drivability priority shift control is switched to the fuel efficiency priority shift control. As described above, by changing the gear ratio allowable fluctuation range according to the user-requested power, it is possible to smoothly perform the transition from the fuel efficiency priority shift control to the drivability priority shift control. Also, when shifting from priority shift control to drivability priority shift control, smooth transition is possible by controlling the allowable fluctuation range of the engine speed after switching to drivability priority shift control according to the user request power. It becomes.

  Furthermore, when an operation mode giving priority to fuel consumption is selected according to a user request, the allowable fluctuation range of the engine speed may be set larger than in a case where it is not. For example, in FIG. 5, when the fuel consumption priority operation mode is selected, the engine speed allowable fluctuation range is set according to the graph 230, and when the fuel consumption priority operation mode is not selected, the engine rotation is performed according to the graph 231. Set the number tolerance fluctuation range. In this way, when the user selects the driving mode with priority on fuel consumption, the tolerance for deterioration in drivability is considered to be large. It is preferable to improve.

  FIG. 6 shows a flowchart corresponding to a shift control example according to the first embodiment. This process is executed when an ECU (not shown) or the like controls the actuators 31 and 32 shown in FIG. 1 based on a user request.

  First, the ECU acquires a user request such as a user request power such as a vehicle speed, an accelerator opening, and a state of a switch (hereinafter referred to as a “fuel consumption priority switch”) for selecting a fuel consumption priority operation mode (step “step”). S101). Next, the ECU determines the required engine power, the target engine speed, the target gear ratio, the allowable engine speed fluctuation range, and the like based on the required user power (step S102). At this time, the engine speed allowable fluctuation range is set to a reference value corresponding to the user requested power. At this time, basically, fuel efficiency priority shift control is selected when the user request power is high, and drivability priority shift control is selected when the user request power is low.

  Next, the ECU determines whether or not the fuel efficiency priority switch is on (step S103). If the fuel efficiency priority switch is on, the ECU sets the allowable engine speed fluctuation range to the value when the fuel efficiency priority switch is on (step S104). ). This is determined according to, for example, the graph 231 in FIG. On the other hand, if it is off, the ECU sets the allowable engine speed fluctuation range to the value when the fuel efficiency priority switch is off (step S105). This is determined, for example, according to the graph 230 of FIG. Then, the ECU sets the gear stage that obtains the maximum transmission efficiency at the target gear ratio as the target gear stage, and performs a shift (step S106).

[Second Embodiment]
In the second embodiment, fuel efficiency priority shift control and drivability priority shift control are selectively used from the viewpoint of exhaust emission. In a state where the exhaust purification catalyst is not warmed up sufficiently to exhibit a normal purification rate, such as when the engine is cold started, the air-fuel ratio is disturbed if the engine speed changes greatly. Emissions of exhaust gas from the engine may be deteriorated. Therefore, when the catalyst is not in an active state capable of exhibiting regular purification performance, by selecting drivability priority shift control, the engine speed change at the time of shift is minimized to prevent deterioration of emissions.

  Specifically, for example, the temperature of the exhaust purification catalyst is detected by a temperature sensor or the like, and it is determined whether or not a predetermined catalyst activation temperature has been reached. When the catalyst is in an active state, fuel consumption priority shift control is performed because there is little risk of emission deterioration. On the other hand, when the catalyst is in an inactive state, drivability priority shift control is performed in order to prevent emission deterioration.

  In addition to the above control, the shift itself may be prohibited when the catalyst is in an inactive state. In the drive control apparatus of the present embodiment, as shown in FIGS. 3A and 3B, a multimode shift from the first speed to the fourth speed is possible. For example, the speed change mechanism (clutch) shown in FIG. The relationship between the transmission ratio and the theoretical transmission efficiency when the mechanisms 21 and 22 and the transmission gear pairs 17 to 20) are not provided is “no transmission mechanism” indicated by a broken line 219 in FIGS. 3 (a) and 3 (b). This is almost the same as the characteristics of the second speed in this example. Therefore, when the catalyst is in an inactive state, the speed change operation is prohibited and the gear position is fixed at the second speed, thereby avoiding fluctuations in the engine speed and preventing emission from deteriorating.

  Furthermore, from the viewpoint of improving emissions, when there is a failure in an exhaust control device of an engine such as an air flow meter or an air-fuel ratio sensor, the shift can be similarly prohibited to prevent the emission from deteriorating.

  FIG. 7 shows a flowchart of a shift control example according to the second embodiment. This process is executed by an ECU connected to an engine exhaust control device or the like. First, the ECU determines whether an exhaust control device such as an air flow meter, an air-fuel ratio sensor, an oxygen sensor, or a catalyst is normal (step S201). If any of the exhaust control devices is not normal (step S201; No), the process proceeds to step S205, and the ECU executes drivability priority shift control.

  On the other hand, when all the exhaust control devices are normal (step S201; Yes), the ECU determines whether the catalyst is warmed up, that is, whether the catalyst is in an active state based on the output of the exhaust temperature sensor or the engine operation history. Is confirmed (step S202). When the warm-up of the catalyst has been completed (step S203; Yes), the ECU executes fuel efficiency priority shift control (step S204). On the other hand, when the catalyst has not been warmed up and is in an inactive state (step S203; No), the ECU executes drivability priority shift control (step S205).

  In the second embodiment, the engine speed allowable fluctuation range may be changed according to the warm-up state of the catalyst. That is, when the catalyst warm-up state is insufficient, drivability priority shift control is performed, and as the catalyst warm-up progresses, the engine speed allowable fluctuation range in the drivability priority shift control is widened. When the warm-up of the catalyst is completed, the fuel consumption priority shift control is switched. Thereby, it is possible to gradually shift to the fuel efficiency priority control while preventing the deterioration of the emission.

[Third embodiment]
In the third embodiment, fuel efficiency priority shift control and drivability priority shift control are selectively used from the viewpoint of reducing the burden on the motor generator and the battery. When the engine speed fluctuates during a shift, the fluctuation is controlled by the operation of the motor generator, so that charging / discharging of the battery occurs. Therefore, in situations where charging / discharging of the battery is restricted, such as when the battery is extremely cold, at a high temperature, or when the battery charge (SOC) is low, drivability priority shift control is performed to suppress fluctuations in the engine speed. Execute. Thereby, the battery power consumption at the time of shifting can be reduced. Further, the battery can be protected to promote deterioration and shorten the life.

  In addition to the above control, in a situation where charging / discharging of the battery is restricted, the shift may be prohibited as described in the second embodiment. Thereby, the energy consumption from the battery accompanying a gear shift can be suppressed. For example, when the battery charge / discharge limit amount reaches the first limit amount, the drivability priority shift control is executed, and when the second limit amount larger than the first limit amount is reached, the shift speed is changed to the first shift amount. It is fixed at the 2nd speed and shifts are prohibited.

  Furthermore, the engine speed allowable fluctuation range in the drivability priority shift control may be changed according to the charge / discharge limit amount of the battery. Specifically, as shown in FIG. 9, when the charge / discharge control amount of the battery is large (that is, when it is desirable not to perform charge / discharge of the battery as much as possible), the engine speed allowable fluctuation range is reduced, and the engine Suppresses fluctuations in rotational speed. On the other hand, when the charge / discharge control amount of the battery is small, the engine speed allowable fluctuation range is increased to improve the fuel consumption as much as possible.

  FIG. 8 is a flowchart of an example of shift control according to the third embodiment. This process is executed while the ECU monitors the charge / discharge limit amount of the battery. First, the ECU calculates the charge / discharge limit amount of the battery from the battery temperature, the charge amount, and the like (step S301). Based on the calculated charge / discharge limit amount, the ECU refers to the characteristics shown in FIG. An allowable rotation speed fluctuation range is calculated (step S302). Then, the ECU sets the gear stage that obtains the maximum transmission efficiency at the target gear ratio as the target gear stage, and performs a shift (step S303).

  As described above, in the third embodiment, from the viewpoint of reducing the burden on the motor generator and the battery, the battery power consumption at the time of shifting can be reduced by properly using the fuel efficiency priority shift control and the drivability priority shift control. it can.

1 shows a schematic configuration of a hybrid device according to an embodiment. The operating characteristics of the continuously variable transmission mode and the fixed speed mode are shown. Examples of fuel efficiency priority shift control and drivability priority shift control are shown. An example of drivability priority shift control in which the gear ratio allowable fluctuation range is variable will be described. The example of a change of the engine speed allowable fluctuation range by user request power is shown. It is a flowchart of the shift control by 1st Example. It is a flowchart of the shift control by 2nd Example. It is a flowchart of the shift control by 3rd Example. The relationship between the charge / discharge limit amount of the battery and the engine speed allowable variation amount is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2, 3 Motor generator 4 Power distribution mechanism 16 Output shaft 21, 22 Clutch mechanism 17, 18, 19, 20

Claims (8)

A drive control device for a hybrid vehicle in which an engine and a motor generator are connected to an output shaft through a power distribution mechanism,
A speed change mechanism that is provided between the power distribution mechanism and the output shaft and performs a speed change over a plurality of continuously variable speed stages;
Shift control means for performing a shift via a fixed gear mode in which a gear ratio is fixed by connecting a plurality of gears for the continuously variable gear to an output shaft;
The shift control means includes: a first shift control that shifts with priority given to power transmission efficiency; and a second shift control that shifts when the gear ratio falls within a predetermined gear ratio allowable fluctuation range. A drive control apparatus for a hybrid vehicle, which is selectively executed according to required power.   The shift control means performs the second shift control when the fluctuation range of the engine speed during the shift is equal to or greater than a predetermined allowable engine speed fluctuation range during the execution of the first shift control. The drive control apparatus for a hybrid vehicle according to claim 1.   The drive control apparatus for a hybrid vehicle according to claim 1 or 2, wherein the shift control means changes the gear ratio allowable fluctuation range according to the required power. A catalyst activity determining means for determining the activity of the catalyst provided in the exhaust passage of the engine;
The drive control device for a hybrid vehicle according to claim 1, wherein the shift control means selects the second shift control when the catalyst is in an inactive state.   5. The drive control apparatus for a hybrid vehicle according to claim 4, wherein the shift control means fixes the shift mechanism at a predetermined shift stage when the catalyst is in an inactive state. Charge / discharge limit amount detection means for detecting a charge / discharge limit amount of a battery connected to the motor generator,
2. The drive control of a hybrid vehicle according to claim 1, wherein the shift control means selects the second shift control when the charge / discharge limit amount is equal to or greater than a first predetermined limit amount. apparatus.   7. The hybrid vehicle according to claim 6, wherein the shift control unit fixes the transmission mechanism at a predetermined shift stage when the charge / discharge limit amount is equal to or greater than a second predetermined limit amount. Drive control device.   The drive control apparatus for a hybrid vehicle according to claim 6, wherein the shift control means changes the gear ratio allowable fluctuation range based on the charge / discharge limit amount.

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