Transmitting state switching control apparatus for hybrid vehicle

Abstract

A control apparatus for a hybrid vehicle for controlling and limiting the transmission of power from an engine to the driving wheels during start-up of the engine to produce a hybrid running mode where the vehicle is powered by both the engine and a motor-generator.

Description

BRIEF DESCRIPTION OF DRAWINGS

This 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 view showing a powertrain of a hybrid vehicle which can employ a transmitting state switching control apparatus according to the present invention.

FIG. 2 is a schematic view showing another powertrain of a hybrid vehicle which can employ the transmitting state switching control apparatus according to the present invention.

FIG. 3 is a schematic plan view showing still another powertrain of a hybrid vehicle which can employ the transmitting state switching control apparatus according to the present invention.

FIG. 4 is a schematic diagram showing an automatic transmission in the powertrains shown in FIGS. 1-3.

FIG. 5 is a schematic speed diagram of the automatic transmission shown in FIG. 4.

FIG. 6 is an engagement logic diagram table showing the relationship between the combination of shift frictional elements in the automatic transmission shown in FIG. 4, and the selected shift speed of the automatic transmission.

FIG. 7 is a schematic block diagram showing a control system of the powertrain shown in FIG. 3.

FIG. 8 is a flow chart showing a program of a basic driving force control performed by an integral controller in the control system.

FIG. 9 is an operation time chart of an EV→HEV mode switching control and a 5→4 downshift control which are performed by the integral controller in the control system shown in FIG. 7.

FIG. 10 is an operation time chart of the 5→4 downshift control and the EV→HEV mode switching control which are performed by the integral controller in the control system shown in FIG. 7

FIG. 11 is an operation time chart of the 5→4 downshift control and the EV→HEV mode switching control in the case of using a disengagement side frictional element as a second clutch.

FIG. 12 is an operation time chart of the EV→HEV mode switching control and the 5→4 downshift control in the case of using the disengagement side frictional element as the second clutch.

FIG. 13 is an operation time chart of the 5→4 downshift control and the EV→HEV mode switching control in the case of using the engagement side frictional elements as the second clutch.

FIG. 14 is an operation time chart of the EV→HEV mode switching control and the 5→4 downshift control in the case of using the engagement side frictional elements as the second clutch.

FIG. 15 is an operation time chart showing a shift control in the HEV mode in the case of using, as the second clutch, the shift frictional elements keeping an engagement state during the shift.

FIG. 16 is an operation time chart showing a shift control in the HEV mode in the case of using the disengagement side frictional elements as the second clutch.

FIG. 17 is an operation time chart showing a shift control in the HEV mode in the case of using the engagement side frictional elements as the second clutch.

Claims

1. An apparatus for controlling a hybrid vehicle having an engine, a motor-generator, and a clutch disposed between the engine and the motor and configured to vary a transmitted torque capacity, comprising: a transmission disposed between the motor-generator and at least one driving wheel having at least two power transmitting paths through the selective engagement of at least one of a plurality of frictional engagement elements; anda controller operable to transition the vehicle from an electric running mode to a hybrid running mode and wherein the controller is configured to selectively permit a slip state where at least one of the frictional engagement elements is allowed to slip during transition to the hybrid running mode from the electric running mode so as to control the driving force transmitted to the at least one driving wheel.

2. The apparatus of claim 1 wherein the slip state of the at least one frictional engagement element relates either before or after a shift is set to the transmitted torque capacity corresponding to a driving force required by the vehicle.

3. The apparatus of claim 2 wherein a starting of the engine and a shift of the transmission are performed at the same time after a progression of the engagement of the clutch during the electric running mode of the vehicle.

4. The apparatus of claim 1 wherein the slip state of the selected at least one of the frictional engagement elements is conditioned on a requested shift of the transmission in response to a requested driving force of the hybrid vehicle.

5. The apparatus of claim 4, wherein the selected at least one of the frictional engagement element permitted to slip is switched during an engine starting process during the start-up of the hybrid running mode.

6. The apparatus of claim 4 wherein the requested transmission shift is a downshift.

7. The apparatus of claim 5 wherein the switching of the frictional engagement element during the engine starting process first brings the frictional engagement elements engaged before and after the shift, to the slip state, and then switches the frictional engagement element disengaged after the shift, to the slip state.

8. The apparatus of claim 5 wherein the switching of the frictional engagement element during the engine starting process first brings the frictional engagement element engaged before the shift, and disengaged after the shift, to the slip state, and then switches the frictional engagement element newly engaged after the shift, to the slip state.

9. The apparatus of claim 5 wherein the switching of the frictional engagement element during the engine starting process first brings the frictional engagement element engaged after the shift, to the slip state, and then switches the frictional engagement element disengaged after the shift, to the slip state.

10. The apparatus of claim 7 wherein the switching to the slip state is performed from a time that the request of the shift arises to a time that the frictional engagement element engaged after the shift is engaged.

11. The apparatus of claim 1 wherein the slip state is conditioned on the transmitted torque capacity, the transmitted torque capacity is held substantially continuous during the start-up of the hybrid running mode even when the requested driving force by the vehicle is varied during the start-up of the hybrid running mode.

12. The apparatus of claim 1 wherein the frictional engagement elements are positioned in the transmission.

13. The apparatus of claim 1 wherein the frictional engagement elements comprise a second clutch.

14. The apparatus of claim 1 wherein the frictional engagement element on a disengagement side is brought to a slip state and then the frictional engagement element on an engagement side is brought to the slip state.

15. A hybrid vehicle, comprising: an engine;a motor-generator;a clutch disposed between the engine and the motor-generator configured to vary a transmitted torque capacity;a transmission disposed between the motor-generator and at least one driving wheel having at least two power transmitting paths through selected engagement of a plurality of frictional engagement elements; anda controller operable to transition the vehicle from an electric running mode to a hybrid running mode and wherein the controller is configured to selectively permit a slip state where at least one of the frictional engagement elements is allowed to slip during transition to the hybrid running mode from the electric running mode so as to control the driving force transmitted to the at least one driving wheel.

16. The vehicle of claim 15 wherein the slip state of the frictional engagement element relates either before or after a shift is set to the transmitted torque capacity corresponding to a driving force required by the vehicle.

17. The vehicle apparatus of claim 15 wherein the slip state is conditioned on the transmitted torque capacity, the transmitted torque capacity is held substantially continuous during a start-up of the hybrid running mode even when the requested driving force by the vehicle is varied during the start-up of the hybrid running mode.

18. A method for controlling a hybrid vehicle having an engine, a motor-generator, a clutch disposed between the engine and the motor and configured to vary a transmitted torque capacity, a transmission disposed between the motor-generator and at least one driving wheel, and a plurality of frictional engagement elements positioned between the motor-generator and the at least one driving wheel, the method comprising: transitioning the vehicle from an electric running mode to a hybrid running mode;allowing at least one of the plurality of frictional engagement elements to slip during transition to the hybrid running mode from the electric running mode so as to control the transmission of power from the engine to the at least one driving wheel during start up of the engine.

19. The method of claim 18, further comprising: holding the transmitted torque capacity substantially constant during the start-up of the hybrid running mode even when the requested driving force by the vehicle is varied during the start-up of the hybrid running mode.

20. The method of claim 18, further comprising: switching the frictional engagement elements that are permitted to slip during start-up of the hybrid running mode.