Vehicle and method of control thereof
First Claim
1. A speed control system for a hybrid electric vehicle, the vehicle having a powertrain comprising at least one engine and at least one electric machine, wherein the system is configured to:
- allow a driver to set a target vehicle speed;
operate the powertrain in first and second speed control modes so as to change a vehicle speed of the hybrid electric vehicle to maintain a prescribed distance behind a followed vehicle without exceeding the target vehicle speed, wherein in the first speed control mode the system limits operation of the powertrain to an electric vehicle (EV) mode in which the electric machine produces drive torque while the engine produces no drive torque, wherein in the second speed control mode the system allows operation of the powertrain in hybrid electric vehicle (HEV) mode and EV inhibit mode, in which the engine produces drive torque;
determine a required rate of acceleration of the vehicle or required amount of drive torque of the powertrain in order to maintain the prescribed distance behind the followed vehicle;
in the first speed control mode, limit operation of the powertrain to the EV mode by limiting a maximum rate of acceleration of the vehicle or maximum amount of drive torque of the powertrain that is commanded from the system to a rate or amount that is achievable by the electric machine while the engine produces no drive torque and that is less than the required rate or amount;
switch from the first speed control mode to the second speed control mode to cause the engine to produce drive torque, when at least one of a prescribed one or more conditions is met, the at least one condition being other than a condition of the achievable rate or amount being less than the required rate or amount; and
in the second speed control mode, command at least the engine to cause a rate of acceleration of the vehicle or amount of drive torque of the powertrain that is at least equal to the required rate or amount.
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Accused Products
Abstract
In an aspect of the invention there is provided a speed control system for a hybrid electric vehicle, the vehicle having at least one engine and at least one electric machine, the system being operable to allow a driver to set a target vehicle speed, the system being operable in first and second speed control modes to control the vehicle to maintain the target vehicle speed, in the first speed control mode the system being configured to limit operation of the vehicle to an electric vehicle (EV) mode, in the second speed control mode the system being configured not to limit operation of the vehicle to the EV mode, wherein when the control system is in the first mode and at least one of a prescribed one or more conditions is met, e.g. a rate of acceleration demanded by the driver or a difference between a target vehicle speed and a current vehicle speed exceeds a respective prescribed threshold value, the system is operable to not limit operation of the vehicle to the EV mode.
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Citations
20 Claims
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1. A speed control system for a hybrid electric vehicle, the vehicle having a powertrain comprising at least one engine and at least one electric machine, wherein the system is configured to:
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allow a driver to set a target vehicle speed; operate the powertrain in first and second speed control modes so as to change a vehicle speed of the hybrid electric vehicle to maintain a prescribed distance behind a followed vehicle without exceeding the target vehicle speed, wherein in the first speed control mode the system limits operation of the powertrain to an electric vehicle (EV) mode in which the electric machine produces drive torque while the engine produces no drive torque, wherein in the second speed control mode the system allows operation of the powertrain in hybrid electric vehicle (HEV) mode and EV inhibit mode, in which the engine produces drive torque; determine a required rate of acceleration of the vehicle or required amount of drive torque of the powertrain in order to maintain the prescribed distance behind the followed vehicle; in the first speed control mode, limit operation of the powertrain to the EV mode by limiting a maximum rate of acceleration of the vehicle or maximum amount of drive torque of the powertrain that is commanded from the system to a rate or amount that is achievable by the electric machine while the engine produces no drive torque and that is less than the required rate or amount; switch from the first speed control mode to the second speed control mode to cause the engine to produce drive torque, when at least one of a prescribed one or more conditions is met, the at least one condition being other than a condition of the achievable rate or amount being less than the required rate or amount; and in the second speed control mode, command at least the engine to cause a rate of acceleration of the vehicle or amount of drive torque of the powertrain that is at least equal to the required rate or amount. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method of controlling speed of a hybrid electric vehicle via a speed control system, wherein the vehicle has a powertrain comprising an engine and an electric machine, the method comprising:
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allowing a driver to set a target vehicle speed; operating the powertrain in first and second speed control modes to change a vehicle speed of the hybrid electric vehicle to maintain a prescribed distance behind a followed vehicle without exceeding the target vehicle speed; wherein in the first speed control mode the system limits operation of the powertrain to an electric vehicle (EV) mode in which the electric machine produces drive torque while the engine produces no drive torque, wherein in the second speed control mode the system allows operation of the powertrain in hybrid electric vehicle (HEV) mode and EV inhibit mode, in which the engine produces drive torque; determining a required rate of acceleration of the vehicle or required amount of drive torque of the powertrain in order to maintain the prescribed distance behind the followed vehicle; in the first speed control mode, limiting operation of the powertrain to the EV mode by limiting a maximum rate of acceleration of the vehicle or maximum amount of drive torque of the powertrain that is commanded from the system to a rate or amount that is achievable by the electric machine while the engine produces no drive torque and that is less than the required rate or amount; switching from the first speed control mode to the second speed control mode to cause the engine to produce drive torque, when at least one of a prescribed one or more conditions is met, the at least one condition being other than a condition of the achievable rate or amount being less than the required rate or amount; and in the second speed control mode, commanding at least the engine to cause a rate of acceleration of the vehicle or amount of drive torque of the powertrain that is at least equal to the required rate or amount.
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Specification