Shift control system of hybrid transmission

• US 20050102082A1
• Filed: 11/12/2004
• Published: 05/12/2005
• Est. Priority Date: 11/12/2003
• Status: Active Grant

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Joe, Shinichiro, Oshidari, Toshikazu
• Granted Patent: US 7,734,401 B2
• Time in Patent Office: Days
• US Class Current: 701/54
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/14 Acceleration
• CPC Class Codes: B60L 2240/36 Temperature of vehicle components or parts
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 2240/547 Voltage
• CPC Class Codes: B60L 2240/549 Current
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 50/62 charged by low-power generators primarily intended to support the batteries, e.g. range extenders
• CPC Class Codes: B60L 58/15 Preventing overcharging
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60W 10/06 : including control of combustion engines
• CPC Class Codes: B60W 10/08 : including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 : including control of change-speed gearings
• CPC Class Codes: B60W 10/26 : for electrical energy, e.g. batteries or capacitors
• CPC Class Codes: B60W 20/00 : Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/11 : using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 2510/0638 : Engine speed
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: B60W 2710/083 : Torque
• CPC Class Codes: F16H 2037/102 : the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 : Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2200/0039 : the gear ratios comprising three forward speeds
• CPC Class Codes: F16H 2200/2005 : with one sets of orbital gears
• CPC Class Codes: F16H 2200/201 : with three sets of orbital gears
• CPC Class Codes: F16H 2200/2025 : using a Ravigneaux set with 5 connections
• CPC Class Codes: F16H 3/728 : with means to change ratio in the mechanical gearing
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• CPC Class Codes: Y02T 10/64 : Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/70 : Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 : Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 : Electric energy management in electromobility
• CPC Class Codes: Y10S 903/902 : Prime movers comprising electrical and internal combustion motors
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/906 : Motor or generator

Abstract

A shift control system of a hybrid transmission for a vehicle is arranged to correct ideal motor/generator torques so as to achieve a target engine speed prior to a target driving torque when an actual engine speed becomes greater than an allowable upper-limit engine speed and to correct the ideal motor/generator torque so as to achieve the target driving torque prior to the target engine speed when the actual engine speed does not become greater than the allowable upper-limit engine speed.

Claims

1. A shift control system of a hybrid transmission for a vehicle, the hybrid transmission being constructed by connecting an internal combustion engine, an output shaft, and two motor/generators through a differential mechanism, the shift control system comprising:

a target value setting section setting a target driving torque, a target engine speed and a target engine torque according to a vehicle driving condition;

an engine torque detecting section obtaining an actual engine torque;

an ideal motor torque calculating section calculating ideal motor/generator torques of the motor/generators so as to achieve the target driving torque and the target engine revolution speed, from the target driving torque, the target engine speed and an actual engine speed on the basis of an equation of motion of the output shaft;

a motor torque correcting section correcting the ideal motor/generator torques within a realizable range indicative of a range of a combination of two torques capable of being generated by the motor/generators under present conditions of the motor/generators and a battery connected to the motor/generators when the combination of the ideal motor/generator torques is out of the realizable range;

the motor torque correcting section correcting the ideal motor/generator torques so as to achieve the target engine speed prior to the target driving torque when the actual engine speed becomes greater than an allowable upper-limit engine speed; and

the motor torque correcting section correcting the ideal motor/generator torque so as to achieve the target driving torque prior to the target engine speed when the actual engine speed does not become greater than the allowable upper-limit engine speed.

2. The shift control system as claimed in claim 1, wherein the engine-speed precedence correction processing comprises

a first correction processing of calculating an exceeding charging/discharging electric power over an battery chargeable/dischargeable electric power on the assumption that the motor/generators output the ideal motor/generator torques, respectively, and of correcting the ideal motor/generator torques so as to control an electric power consumed by the motor/generators within the battery chargeable/dischargeable electric power and to achieve the target engine speed,

a second correction processing of correcting the ideal motor/generator torques so as to control actual motor/generator torques within limit values and to achieve the target engine speed when the ideal motor/generator torques corrected by the first correction processing are outputted and when the actual motor/generator torques of the motor/generators are over the limit values, and

a third correction processing of calculating an exceeding-charging electric power over a battery chargeable/dischargeable electric power and an exceeding regenerative electric power over a rated power of the motor/generators on the assumption that the motor/generators output ideal motor/generator torques corrected by the second correction processing and of correcting the target engine torque so as to decrease the engine power by a quantity corresponding to a larger one of the exceeding-charging electric power and the exceeding regenerative electric power.

3. The shift control system as claimed in claim 2, wherein the hybrid transmission further comprises at least one of a brake which is capable of fixing one of rotational elements of the differential mechanism and a clutch which is capable of connecting two of the rotational elements, and changes a transmission ratio of the hybrid transmission by controlling engagement and disengagement of at least one of the brake and the clutch,

wherein the third correction processing achieves the lowering of the engine power by decreasing the target engine torque and by slidingly engaging one of the brake and clutch.

4. The shift control system as claimed in claim 2, wherein the third correction processing calculates the exceeding regenerative electric power over the rated power of the motor/generators on the assumption that the motor/generators output ideal motor/generator torques corrected by the second correction processing and corrects the target engine torque so as to downwardly correct the ideal motor/generator torque of the motor/generator put in a regenerative state so as to limit the exceeding regenerative electric power within a regeneration enabling electric power.

5. The shift control system as claimed in claim 1, further comprising a battery condition detecting section which detects a storage state of the battery.

6. The shift control system as claimed in claim 1, wherein when the actual engine speed is greater than a value obtained by subtracting a margin from an upper limit, it is determined that the actual engine speed becomes greater than the allowable upper-limit engine speed.

7. The shift control system as claimed in claim 1, further comprising a vehicle driving condition detecting section which detects an accelerator opening, a vehicle speed and a battery condition.

8. A method of controlling a hybrid drive system constructed by a hybrid transmission and an internal combustion engine, the hybrid transmission being constructed by connecting an internal combustion engine, an output shaft, and two motor/generators through a differential mechanism, the method comprising:

setting a target driving torque, a target engine speed and a target engine torque according to a vehicle driving condition;

obtaining an actual engine torque;

calculating ideal motor/generator torques of the motor/generators so as to achieve the target driving torque and the target engine revolution speed, from the target driving torque, the target engine speed and an actual engine speed on the basis of an equation of motion of the output shaft;

correcting the ideal motor/generator torques within a realizable range indicative of a range of a combination of two torques capable of being generated by the motor/generators under present conditions of the motor/generators and a battery connected to the motor/generators when the combination of the ideal motor/generator torques is out of the realizable range;

correcting the ideal motor/generator torques so as to achieve the target engine speed prior to the target driving torque when the actual engine speed becomes greater than an allowable upper-limit engine speed; and

correcting the ideal motor/generator torque so as to achieve the target driving torque prior to the target engine speed when the actual engine speed does not become greater than the allowable upper-limit engine speed.

9. A shift control system of a hybrid transmission for a vehicle, the hybrid transmission being constructed by connecting an internal combustion engine, an output shaft, and two motor/generators through a differential mechanism, the shift control system comprising:

target value setting means for setting a target driving torque, a target engine speed and a target engine torque according to a vehicle driving condition;

engine torque detecting means for obtaining an actual engine torque;

ideal motor torque calculating means for calculating ideal motor/generator torques of the motor/generators so as to achieve the target driving torque and the target engine revolution speed, from the target driving torque, the target engine speed and an actual engine speed on the basis of an equation of motion of the output shaft;

motor torque correcting means for correcting the ideal motor/generator torques within a realizable range indicative of a range of a combination of two torques capable of being generated by the motor/generators under present conditions of the motor/generators and a battery connected to the motor/generators when the combination of the ideal motor/generator torques is out of the realizable range;

the motor torque correction means correcting the ideal motor/generator torques so as to achieve the target engine speed prior to the target driving torque when the actual engine speed becomes greater than an allowable upper-limit engine speed; and

motor torque correction means correcting the ideal motor/generator torque so as to achieve the target driving torque prior to the target engine speed when the actual engine speed does not become greater than the allowable upper-limit engine speed.

10. A hybrid drive system comprising:

an internal combustion engine;

an output shaft connect to a wheel driveline of a vehicle;

two motor/generators receiving electric power from a battery;

a differential mechanism relationally connecting the engine, the output shaft and the motor/generators;

an accelerator opening detector detecting an accelerator opening;

a vehicle speed detector detecting a vehicle speed; and

a controller connected to the engine, the motor/generators, the accelerator opening detector and the vehicle speed detector, the controller being configured,

to determine a target driving torque, a target engine speed and a target engine torque according to the accelerator opening and the vehicle speed,

to obtain an actual engine torque,

to obtain ideal motor/generator torques for achieving the target driving torque and the target engine speed, from the target driving torque, the target engine speed and the actual engine speed,

to correct the ideal motor/generator torques within a motor torque generable range limited by a condition of the battery when the ideal torque becomes out of the motor torque generable range,

to correct the ideal motor/generator torques so as to achieve the target driving torque prior to the target engine speed when the actual engine speed does not exceed an allowable upper limit of the actual engine speed, and

to correct the ideal motor/generator torques so as to achieve the target engine speed prior to the target engine speed when the actual engine speed exceeds the allowable upper limit.