Vehicle deceleration control apparatus

1. A deceleration control apparatus for controlling a deceleration value of a vehicle, comprising:

deceleration-value setting means including a plurality of deceleration-value setting devices operated by a user;

a target-deceleration-value control portion operable to change a target deceleration value of the vehicle according to an operation of the deceleration-value setting means; and

a brake control portion operable to control a braking force to be applied to the vehicle, according to the target deceleration value changed by the target-deceleration-value control portion, wherein

said target-deceleration-value control portion is operable to successively change the target deceleration value of the vehicle in response to successive operations of one and another of said plurality of deceleration-value setting devices such that the target deceleration value, which is changed according to the operation of said one deceleration-value setting device by the user, is subsequently changed according to the operation of said another deceleration-value setting device by the user.

2. The deceleration control apparatus according to claim 1 , wherein the vehicle includes a drive wheel, an engine and an electric motor which are operatively connected to said drive wheel, and further includes an automatic transmission disposed between said engine and said drive wheel, and

wherein said brake control portion is operable to control a speed ratio of said automatic transmission for controlling an engine braking torque, and to control a torque generated by said electric motor, for thereby controlling said braking force to be applied to the vehicle.

3. The deceleration control apparatus according to claim 2 , wherein said brake control portion is operable to control as said braking force a drive-power-source braking torque to be applied to the vehicle by said engine and said electric motor, such that said drive-power-source braking torque is equal to a sum of said engine braking torque and a regenerative torque generated by said electric motor.

4. The deceleration control apparatus according to claim 2 , wherein said brake control portion is operable to control as said braking force a drive-power-source braking torque to be applied to the vehicle by said engine and said electric motor such that said drive-power-source braking torque is equal to said engine braking torque minus a forward vehicle drive torque generated by said electric motor.

5. The deceleration control apparatus according to claim 2 , wherein said target-deceleration-value control portion is operable to change said target deceleration value in steps upon successive operations of each of said plurality of deceleration-value setting devices such that the target deceleration value is changed by a predetermined amount each time said each deceleration-value setting device is operated, said brake control portion controlling the speed ratio of said automatic transmission and the torque of said electric motor such that an amount of change of a deceleration value of the vehicle caused by an amount of change of the torque of the electric motor corresponding to said predetermined amount of change of said target deceleration value is smaller than an amount of change of the deceleration value caused by an amount of change of said engine braking toque corresponding to said predetermined amount of change of said target deceleration value.

6. The deceleration control apparatus according to claim 1 , wherein said target-deceleration-value control portion is operable, in response to an operation of any one of said plurality of deceleration-value setting devices while said braking force is not being controlled by said brake control portion, to set said target deceleration value to an initial value on the basis of a reference deceleration value to be obtained upon the operation of said any one of said plurality of deceleration-value setting devices.

7. The deceleration control apparatus according to claim 1 , wherein said target-deceleration-value control portion is operable, in response to an operation of any one of said plurality of deceleration-value setting devices while said braking force is not being controlled by said brake control portion, to set said target deceleration value to an initial value on the basis of a reference deceleration value which is determined by a running speed of the vehicle upon the operation of said any one of said plurality of deceleration-value setting devices.

8. The deceleration control apparatus according to claim 1 , wherein the vehicle includes a drive wheel, an engine and an electric motor which are operatively connected to said drive wheel, and further includes an automatic transmission which is disposed between said engine and said drive wheel and which has a plurality of forward-drive gear positions, and said automatic transmission has a first forward-drive shift-range in which all of said plurality of forward-drive gear positions are available for automatic shifting of the automatic transmission, and at least one second forward-drive shift range in which at least one high-speed gear position selected from among said plurality of forward-drive gear positions is not available for automatic shifting of the automatic transmission, and

wherein said brake control portion is operable to control the speed ratio of said automatic transmission for controlling an engine braking torque, and to control a torque generated by said electric motor, for thereby controlling said braking force to be applied to the vehicle, and said target-deceleration-value control portion is operable, in response to an operation of any one of said plurality of deceleration-value setting devices while said braking force is not being controlled by said brake control portion, to set said target deceleration value to an initial value on the basis of a reference deceleration value to be obtained when said first forward-drive shift range of said automatic transmission is selected.

9. The deceleration control apparatus according to claim 1 , wherein the vehicle includes a manually operable lever, and said plurality of deceleration-value setting devices include a first deceleration-value setting device operable by said lever to increase and reduce said target deceleration value.

10. The deceleration control apparatus according to claim 9 , wherein said lever is located at one of positions of a center console, a floor and an instrument panel of the vehicle.

11. The deceleration control apparatus according to claim 9 , wherein the vehicle includes a drive wheel and a transmission operatively connected to said drive wheel, and said lever is a shift lever operable to control a shifting action of said transmission.

12. The deceleration control apparatus according to claim 9 , wherein said lever has a deceleration-control-mode selecting position for selecting a deceleration control mode in which said first deceleration-value setting device is operable by an operation of the lever.

13. The deceleration control apparatus according to claim 12 , wherein said first deceleration-value setting device includes two switches which are turned on by respective movements of said lever from said deceleration-control-mode selecting position, to respectively increase and reduce said target deceleration value.

14. The deceleration control apparatus according to claim 12 , further comprising a deceleration-control-mode selector switch which is turned on to establish said deceleration control mode when said lever is operated to said deceleration-control-mode selecting position.

15. The deceleration control apparatus according to claim 12 , wherein said plurality of deceleration-value setting devices includes a second deceleration-value setting device which is operable to increase and reduce said target deceleration value irrespective of whether said deceleration control mode has been selected by operating said lever to said deceleration-control-mode selecting position.

16. The deceleration control apparatus according to claim 1 , wherein the vehicle includes a manually operable lever, and said plurality of deceleration-value setting devices includes a second deceleration-value setting device operable irrespective of an operation of said lever to increase and reduce said target deceleration value.

17. The deceleration control apparatus according to claim 16 , wherein said second deceleration-value setting device is provided on a steering wheel of the vehicle or located at a position near said steering wheel.

18. The deceleration control apparatus according to claim 1 , wherein said brake control portion is operable to calculate a required value of said, braking force to be applied to the vehicle, on the basis of said target deceleration value changed by said target-deceleration-value control portion, and according to a predetermined relationship between said required value and said target deceleration value.