Hybrid drive system wherein clutch is engaged when engine speed has exceeded motor speed upon switching from motor drive mode to engine drive mode

• US 6,994,177 B2
• Filed: 10/01/2003
• Issued: 02/07/2006
• Est. Priority Date: 10/08/1999
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Endo, Hiroatsu, Oba, Hidehiro, Ito, Masatoshi, Hoshiya, Kazumi
• Primary Examiner(s): Ellis, Christopher P.
• Assistant Examiner(s): Bottorff, Christopher
• Application Number:
  US10/674,544
• Publication Number:
  US 20040060753A1
• Time in Patent Office: 860 Days
• Field of Search: 180/65.2, 180/65.4, 180/65.6, 180/65.8, 701/22
• US Class Current: 180/65.21
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/387 Actuated clutches, i.e. clutches engaged or disengaged by electric, hydraulic or mechanical actuating means
• CPC Class Codes: B60K 6/48 Parallel type
• CPC Class Codes: B60K 6/543 the transmission being a continuously variable transmission
• CPC Class Codes: B60L 2260/26 Transition between different drive modes
• CPC Class Codes: B60L 50/61 by batteries charged by engine-driven generators, e.g. series hybrid electric vehicles
• CPC Class Codes: B60W 10/02 including control of driveline clutches
• 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 10/107 with endless flexible members
• 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 20/40 Controlling the engagement or disengagement of prime movers, e.g. for transition between prime movers power-up or power-down of the driveline B60W30/192
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2710/025 Clutch slip, i.e. difference between input and output speeds
• CPC Class Codes: F16D 2500/1066 Hybrid
• CPC Class Codes: F16H 3/725 with means to change ratio in the mechanical gearing
• CPC Class Codes: F16H 61/66 specially adapted for continuously variable gearings control of exclusively fluid gearing F16H61/38
• CPC Class Codes: F16H 9/18 : only one flange of each pulley being adjustable
• CPC Class Codes: Y02T 10/62 : Hybrid vehicles
• 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: Y10S 903/903 : having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/905 : Combustion engine
• CPC Class Codes: Y10S 903/91 : Orbital, e.g. planetary gears
• CPC Class Codes: Y10S 903/918 : Continuously variable
• CPC Class Codes: Y10S 903/946 : Characterized by control of driveline clutch

Abstract

A hybrid vehicle drive system including (a) an engine, (b) an electric motor, (c) a planetary gear device having a first rotary element connected to the engine, a second rotary element connected to the electric motor and connected through a first clutch to an output member connected to vehicle drive wheel, and a third rotary element connected through a second clutch to the output member, (d) a forward-motor-drive control device for engaging the first clutch and releasing the second clutch to thereby establish a forward motor drive mode in which the vehicle is driven in a forward direction by the electric motor, (e) a forward-engine-drive control device for engaging at least the second clutch to establish an engine-drive mode in which the vehicle is driven in the forward direction by the engine, and (f) a second-clutch control device operable upon switching of a vehicle drive mode from the forward motor drive mode to the forward engine drive mode, for engaging the second clutch only after the engine speed has exceeded the motor speed.

Claims

1. A hybrid drive system for an automotive vehicle, comprising:

(a) an engine operable by combustion of a fuel to generate a drive force;

(b) an electric motor;

(c) an output member operatively connected to a drive wheel of the vehicle for driving the vehicle;

(d) a planetary gear device having a first rotary element connected to said engine, a second rotary element connected to said electric motor, and a third rotary element;

(e) a first clutch through which said second rotary element is connected to said output member;

(f) a second clutch through which said third rotary element is connected to said output member;

(g) means for controlling the hybrid drive system to engage said first clutch and release said second clutch to thereby establish a forward motor drive mode in which the automotive vehicle is driven in a forward direction by operation of said electric motor while said engine is at rest;

to engage both of said first clutch and said second clutch to establish a direct engine drive mode in which the automotive vehicle is driven in the forward direction by operation of said engine, with said planetary gear device being rotated as a unit, and to release said first clutch and engage said second clutch to establish an engine-and-motor drive mode in which the automotive vehicle is driven in the forward direction by operation of both of said engine and said electric motor;

to determine whether said engine is likely to stall if said direct engine drive mode is established, when it is determined that a vehicle drive mode should be switched from said forward motor drive mode to said direct engine drive mode; and

to establish said engine-and-motor drive mode, when it is determined that the engine is likely to stall if said direct engine drive mode is established.

2. The hybrid drive system according to claim 1, wherein said means determines that the engine is likely to stall if said direct engine drive mode is established, when a speed of said output member is lower than a predetermined threshold.

3. The hybrid drive system according to claim 2, wherein said predetermined threshold is a predetermined constant value.

4. The hybrid drive system according to claim 2, wherein said predetermined threshold is a variable which changes with a change in said speed of said output member.

5. The hybrid drive system according to claim 4, wherein said variable is determined on the basis of an operating amount of a vehicle accelerating member.

6. The hybrid drive system according to claim 5, wherein said variable decreases with an increase of an operating amount of said vehicle accelerating member.

7. The hybrid drive system according to claim 2, wherein said means determines whether the engine is likely to stall if said direct engine drive mode is established, after it is determined that a difference between a speed of the engine and a speed of said electric motor begins to decrease.

8. A method of controlling a hybrid drive system for an automotive vehicle, said hybrid drive system comprising:

(a) an engine operable by combustion of a fuel to generate a drive force, (b) an electric motor, (c) an output member operatively connected to a drive wheel of the vehicle for driving the vehicle, (d) a planetary gear device having a first rotary element connected to said engine, a second rotary element connected to said electric motor, and a third rotary element, (e) a first clutch through which said second rotary element is connected to said output member, and (f) a second clutch through which said third rotary element is connected to said output member, said method comprising the steps of;

engaging said first clutch and releasing said second clutch to thereby establish a forward motor drive mode in which the automotive vehicle is driven in a forward direction by operation of said electric motor while said engine is at rest;

engaging both of said first clutch and said second clutch to establish a direct engine drive mode in which the automotive vehicle is driven in the forward direction by operation of said engine, with said planetary gear device being rotated as a unit, and for releasing said clutch and engaging said second clutch to establish an engine-and-motor drive mode in which the automotive vehicle is driven in the forward direction by operations of both of said engine and said electric motor;

determining whether said engine is likely to stall if said direct engine drive mode is established, when it is determined that a vehicle drive mode should be switched from said forward motor drive mode to said direct engine drive mode; and

commanding said forward-engine-drive control means to establish said engine-and-motor drive mode, when it is determined that the engine is likely to stall if said direct engine drive mode is established.