Hybrid electric vehicle powertrain with regenerative braking
First Claim
1. A method for braking a vehicle powertrain having a first driving axle exclusively driven electrically, the first driving axle exclusively having only electric regenerative brakes, the vehicle having also a second driving axle driven by an internal combustion engine, the second driving axle exclusively having only friction brakes;
- the method comprising;
monitoring a headroom of regenerative braking available and dissipating power through a thermal resistor to make more headroom available for regenerative braking;
electrically braking the first driving axle regeneratively up to a first level;
frictionally braking the second driving axle when a braking requirement of the vehicle is greater than the first level; and
additionally compression braking the second driving axle with the internal combustion engine up to the first level and above the first level of braking the vehicle.
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Accused Products
Abstract
A powertrain control method and strategy for a hybrid electric vehicle is disclosed including establishing electric motor-generator regenerative braking on a first driving axle and engine compression braking for a second driving axle when the vehicle is in a deceleration mode and friction braking the first driving axle when regenerative braking, the friction braking complementing regenerative braking to satisfy a given total braking request.
90 Citations
10 Claims
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1. A method for braking a vehicle powertrain having a first driving axle exclusively driven electrically, the first driving axle exclusively having only electric regenerative brakes, the vehicle having also a second driving axle driven by an internal combustion engine, the second driving axle exclusively having only friction brakes;
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the method comprising;
monitoring a headroom of regenerative braking available and dissipating power through a thermal resistor to make more headroom available for regenerative braking;
electrically braking the first driving axle regeneratively up to a first level;
frictionally braking the second driving axle when a braking requirement of the vehicle is greater than the first level; and
additionally compression braking the second driving axle with the internal combustion engine up to the first level and above the first level of braking the vehicle.
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2. A method for braking a vehicle with a hybrid electric powertrain having first and second driving axles, an electric power system comprising an electric motor-generator and battery, an internal combustion engine with an engine throttle, a vehicle system controller including an engine throttle control and a motor-generator control, the electric motor-generator being driveably connected to the first driving axle and the internal combustion engine being driveably connected to the second driving axle, the internal combustion engine having a driver-operated engine throttle;
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the method comprising the steps of;
determining whether the engine throttle is moved to a throttle tip-out position;
calculating a total compression braking request by the vehicle controller as a function of powertrain operating variables in response to a driver demand for vehicle braking;
monitoring battery state-of-charge;
comparing monitored battery state-of-charge to a predetermined battery state-of-charge to establish a current state-of-charge headroom when the total compression braking request is calculated; and
compression regenerative braking the first driving axle when a current state-of-charge headroom exceeds a predetermined amount whereby the vehicle deceleration with regenerative braking. - View Dependent Claims (4, 9)
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3. A method for braking a vehicle with a hybrid electric powertrain having first and second driving axles, an electric power system comprising an electric motor-generator and battery, an internal combustion engine with an engine throttle, a vehicle system controller including an engine throttle control and a motor-generator control, the electric motor-generator being driveably connected to the first driving axle and the internal combustion engine being driveably connected to the second driving axle, the internal combustion engine having a driver-operated engine throttle;
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the method comprising the steps of;
determining whether the engine throttle is moved to a throttle tip-out position;
calculating a total compression braking request by the vehicle controller in response to a driver demand for vehicle braking;
monitoring battery state-of-charge;
comparing monitored battery state-of-charge to a predetermined battery state-of-charge to establish a current state-of-charge headroom when the total compression braking request is calculated; and
establishing a mechanical driving connection between the engine and the second driving axle when a current state-of-charge headroom is less than a predetermined amount whereby the vehicle decelerates with engine compression braking. - View Dependent Claims (5, 10)
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6. A method for braking a vehicle with a hybrid electric powertrain having first and second driving axles, an electric motor-generator and battery system and an internal combustion engine with an engine throttle, a vehicle system controller including an engine throttle control and a motor-generator control, the electric motor-generator being driveably connected to the first driving axle and the internal combustion engine being driveably connected to the second driving axle, a friction brake including driver-actuated brake element for initiating a service braking request, a friction brake element connected to the second driving axle for friction braking the vehicle with friction braking torque at only the second axle, the internal combustion engine throttle;
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the method comprising the steps of;
determining whether the driver has requested service braking;
calculating a total service braking request when the driver has actuated the brake element;
monitoring battery state-of-charge;
comparing monitored battery state-of-charge to a predetermined battery state-of-charge to establish a current state-of-charge headroom when the total service braking request is calculated; and
providing service regenerative braking of the vehicle when a current state-of-charge headroom exceeds a predetermined amount whereby the vehicle decelerates with regenerative braking. - View Dependent Claims (8)
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7. A method for braking a vehicle with a hybrid electric powertrain having first and second driving axles, an electric power system comprising an electric motor-generator and battery, an internal combustion engine with an engine throttle control, a vehicle system controller including an engine throttle control and a motor-generator control, the electric motor-generator being driveably connected to the first driving axle and the internal combustion engine being driveably connected to the second driving axle;
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a driver-actuated brake element for initiating a service braking request, a friction brake including a friction brake element connected to the second driving axle for friction braking the vehicle with friction braking torque at only the second axle, the internal combustion engine having a driver-operated engine throttle;
the method comprising the steps of;
determining whether the driver has requested service braking;
calculating a total service braking request where the driver has actuated the brake element;
monitoring battery state-of-charge;
comparing monitored battery state-of-charge to a predetermined battery state-of-charge to establish a current state-of-charge headroom when the total service braking request is calculated; and
applying the friction brake to effect friction service braking of the vehicle when a current state-of-charge headroom does not exceed a predetermined amount whereby the vehicle decelerates with friction braking at the second driving axle.
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Specification