Controlling device and method for hybrid vehicle

Abstract

A mode switching controlling device and method switches a hybrid drive (HEV) mode to an electric drive (EV) mode without engine stoppage shock. A fourth-to-fifth speed upshifting command is generated due to reduction in an accelerator opening. Then, an HEV-to-EV-mode switching command is generated. A command pressure of a direct clutch is set to 0, and an actual-pressure reduction disengages the direct clutch, causing an automatic transmission to be in a neutral state. When a first time elapses from generation of the switching command, a first clutch command pressure is set to its maximum value, and the first clutch disengages by an actual pressure increase. When a second time elapses, the engine is stopped by reducing engine torque to perform mode switching. A front brake command pressure is set to a precharge pressure when the second time elapses and to its maximum value at a later time when a gear-switching rotation matching controlling operation of a motor-generator is ended, so that the front brake is engaged due to an actual pressure increase for upshifting from the fourth to fifth speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The description herein makes reference to the accompanying drawings wherein like reference numerals refer to like parts throughout the several views, and wherein:

FIG. 1 is a schematic plan view of a power train of a hybrid vehicle in which an embodiment of the invention can be incorporated;

FIG. 2 is a schematic plan view of another power train of the hybrid vehicle in which an embodiment of the invention can be incorporated;

FIG. 3 is a schematic plan view of still another power train of the hybrid vehicle in which an embodiment according to the invention can be incorporated;

FIG. 4 is a general view of an automatic transmission in any of the power train configurations shown in FIGS. 1 to 3;

FIG. 5 is an engagement logic diagram showing relationships between combinations of engagements of transmission friction elements in the automatic transmission shown in FIG. 4 and selected gears of the automatic transmission;

FIG. 6 is a block diagram of a controlling system of the power train shown in FIG. 3;

FIG. 7 is a flowchart showing a program of a basic driving force controlling operation that is executed by an integrated controller in the controlling system; and

FIG. 8 is an operation time chart of an HEV-to-EV-mode switching controlling operation that is executed by the integrated controller in the controlling system shown in FIG. 6.

Claims

1. A controlling device for a hybrid vehicle, comprising: an engine;a motor-generator;a first clutch whose torque transfer capacity is changeable between the engine and the motor-generator;a second clutch whose torque transfer capacity is changeable between the motor-generator and a driving wheel; anda controller configured to: control a selection between an electric drive mode, in which the hybrid vehicle travels by using the motor-generator while the first clutch is disengaged and the second clutch is engaged, and a hybrid drive mode, in which the hybrid vehicle travels by at least driving force of the engine while the first clutch and the second clutch are engaged; andperform mode switching from the hybrid drive mode to the electric drive mode by reducing the torque transfer capacity of the second clutch to stop the engine and by disengaging the first clutch responsive to reducing the torque transfer capacity of the second clutch.

2. The controlling device according to claim 1, further comprising: an automatic transmission disposed between the motor-generator and the driving wheel.

3. The controlling device according to claim 2 wherein the second clutch is a transmission friction element for maintaining the automatic transmission in a power transmission state.

4. The controlling device according to claim 2, further comprising: an engaged transmission friction element of the automatic transmission; anda disengaged transmission friction element of the automatic transmission; and wherein the controller is further operable to: disengage the engaged transmission friction element and engage the disengaged transmission friction element to accomplish gear shifting of the automatic transmission, wherein the engaged transmission friction element that is disengaged is the second clutch; andperform the mode switching at the time of the gear shifting of the automatic transmission.

5. The controlling device according to claim 4 wherein the controller is further operable to: subject the motor-generator to a rotation matching controlling operation so that an input-side rotational speed of the automatic transmission approaches a rotational speed set after the gear shifting, while the second clutch is in a slipping condition or is disengaged.

6. The controlling device according to claim 1 wherein the controller is further operable to: disengage the first clutch after engine torque set during operation of the engine disappears by stopping the engine, based on an elapsed time measured from a moment when a mode switching command for switching from the hybrid drive mode to the electric drive mode is issued.

7. The controlling device according to claim 3, further comprising: a reverse driving inhibiting element disposed at the transmission system and operating as a second clutch wherein the engine is stopped and the first clutch is disengaged immediately at a moment when a mode switching command for switching from the hybrid drive mode to the electric drive mode is issued.

8. The controlling device according to claim 7 wherein the reverse driving inhibiting element is a one-way clutch.

9. The controlling device according to claim 1, further comprising: a shock produced when the engine is stopped, the second clutch operable to absorb the shock.

10. The controlling device according to claim 1 wherein the controller is further configured to perform mode switching from the hybrid drive mode to the electric drive mode by reducing the torque transfer capacity of the second clutch to stop the engine and by disengaging the first clutch while reducing the torque transfer capacity of the second clutch or after reducing the torque transfer capability of the second clutch,

11. A controlling device for a hybrid vehicle, comprising: an engine;a motor-generator;first means for changing a torque transfer capacity between the engine and the motor-generator;second means for changing a torque transfer capacity between the motor-generator and a driving wheel;means for controlling a selection between an electric drive mode, in which the hybrid vehicle travels by using the motor-generator while the first changing means is disengaged and the second changing means is engaged, and a hybrid drive mode, in which the hybrid vehicle travels by at least driving force of the engine when the first changing means and the second changing means are engaged; andmeans for performing mode switching from the hybrid drive mode to the electric drive mode by reducing the torque transfer capacity of the second changing means to stop the engine and by disengaging the first changing means responsive to reducing the torque transfer capacity of the second changing means.

12. A method for controlling a hybrid vehicle, the hybrid vehicle including an engine, a motor-generator, a first clutch with a torque transfer capacity changeable between the engine and the motor-generator, a second clutch with a torque transfer capacity changeable between the motor-generator and a driving wheel, the method comprising: controlling a selection between an electric drive mode, in which the hybrid vehicle travels by using the motor-generator while the first clutch is disengaged and the second clutch is disengaged, and a hybrid drive mode, in which the hybrid vehicle travels by at least driving force of the engine while the first clutch and the second clutch are engaged; andperforming mode switching from the hybrid drive mode to the electric drive mode by reducing the torque transfer capacity of the second clutch to stop the engine and by disengaging the first clutch responsive to reducing the torque transfer capacity of the second clutch.

13. The method according to claim 12 wherein the hybrid vehicle further includes an automatic transmission disposed between the motor-generator and the driving wheel, the method further comprising: maintaining the automatic transmission in a power transmission state using a transmission friction element as the second clutch.

14. The method according to claim 12 wherein the hybrid vehicle further includes an automatic transmission disposed between the motor-generator and the driving wheel, the method further comprising: engaging a first transmission friction element of the automatic transmission;disengaging a second transmission friction element of the automatic transmission; and wherein performing the mode switching further includes:gear shifting the automatic transmission by disengaging the first transmission friction element and engaging the second transmission element, wherein the first transmission friction element is the second clutch.

15. The method according to claim 14, further comprising: subjecting the motor-generator to a rotation matching controlling operation so that an input-side rotational speed of the automatic transmission approaches a rotational speed set after the gear shifting, while the torque transfer capacity of the second clutch is low.

16. The method according to claim 12, further comprising: disengaging the first clutch after engine torque set during operation of the engine disappears by stopping the engine, based on an elapsed time measured from a moment when a mode switching command for switching from the hybrid drive mode to the electric drive mode is issued.

17. The method according to claim 16 wherein the hybrid vehicle further includes an automatic transmission disposed between the motor-generator and the driving wheel, the method further comprising: engaging a disengaged transmission friction element and inhibiting reverse driving from the driving wheel to the engine by slipping, wherein the engine is stopped and the first clutch is disengaged immediately at a moment when a mode switching command for switching from the hybrid drive mode to the electric drive mode is issued.

18. The method according to claim 12, further comprising: absorbing a shock produced when the engine is stopped using the second clutch.