Torque modulation in a hybrid vehicle downshift during regenerative braking
First Claim
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1. A hybrid electric vehicle powertrain system comprising:
- an automatic transmission including multiple gear ratios for delivering an output torque to a set of drive wheels;
a controller configured to effect a downshift between gear ratios during regenerative braking which tends to cause variations in the output torque, said controller further configured to counteract the variations to maintain the output torque substantially constant and prevent significant ramping or spiking of the output torque;
an engine for generating a first input torque that is transferred to the transmission; and
a motor for generating a second input torque that is transferred to the transmission;
wherein the controller is configured to modulate the first input torque during the downshift to counteract the variations.
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Abstract
A controller and a control strategy minimizes shift shock in a hybrid electric vehicle during a downshift conducted while the vehicle is in a regenerative braking mode by maintaining total powertrain torque at a desired target during the downshift. The controller has three preferable modes including modulating just engine torque, modulating just electric motor torque or simultaneously modulating both motor and engine torque.
38 Citations
19 Claims
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1. A hybrid electric vehicle powertrain system comprising:
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an automatic transmission including multiple gear ratios for delivering an output torque to a set of drive wheels; a controller configured to effect a downshift between gear ratios during regenerative braking which tends to cause variations in the output torque, said controller further configured to counteract the variations to maintain the output torque substantially constant and prevent significant ramping or spiking of the output torque; an engine for generating a first input torque that is transferred to the transmission; and a motor for generating a second input torque that is transferred to the transmission; wherein the controller is configured to modulate the first input torque during the downshift to counteract the variations. - View Dependent Claims (2, 3, 4)
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5. A method for reducing shift shock in a hybrid vehicle powertrain system including an automatic transmission for delivering an output torque through multiple gear ratios comprising:
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effecting a downshift between the gear ratios during regenerative braking which tends to cause variations in the output torque; measuring an output torque signal indicative of the output torque; maintaining, using a controller configured to counteract the variations, the output torque signal substantially constant to prevent significant ramping or spiking of the output torque signal during the downshift; sending an engine torque signal to an engine to cause the engine to generate a first input torque; transferring the first input torque to the transmission; sending a motor torque signal to an electric motor to cause the motor to generate a second input torque; and transferring the second input torque to the transmission, wherein maintaining the output torque signal substantially constant further includes modulating the engine and motor torque signals during the downshift to counteract the variations. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. A method for reducing shift shock in a hybrid vehicle powertrain system including an automatic transmission with multiple gear ratios comprising:
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delivering an output torque from the transmission; effecting a downshift between the gear ratios during regenerative braking which tends to cause variations in the output torque; maintaining, using a controller configured to counteract the variations, the output torque substantially constant to prevent significant ramping or spiking of the output torque during the downshift; causing an engine to generate a first input torque; transferring the first input torque to the transmission; causing an electric motor to generate a second input torque; transferring the second input torque to the transmission; and wherein maintaining the output torque substantially constant further includes modulating the first and second input torques during the downshift to counteract the variations. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification