METHOD AND SYSTEM FOR CYLINDER COMPRESSION DIAGNOSTICS
First Claim
Patent Images
1. A method for a hybrid vehicle comprising:
- spinning an engine unfueled using motor torque with intake valve timing advanced and an intake throttle open; and
based on a change in battery current during the spinning, indicating cylinder compression degradation.
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Abstract
Methods and systems are provided for performing a non-intrusive engine compression test. When compression testing is requested, a hybrid vehicle engine may be spun unfueled using energy from a battery driven electric motor. Changes in battery current over multiple engine cycles is used to infer cylinder compression parameters and assess cylinder compression degradation.
32 Citations
20 Claims
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1. A method for a hybrid vehicle comprising:
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spinning an engine unfueled using motor torque with intake valve timing advanced and an intake throttle open; and based on a change in battery current during the spinning, indicating cylinder compression degradation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for a hybrid vehicle, comprising,
in response to a request for compression testing, spinning an engine unfueled using torque from a battery-driven motor with an intake valve timing advanced and an intake throttle open; - and
indicating degradation of cylinder compression responsive to variations in cylinder compression pressure inferred from changes in battery current during the spinning. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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19. A hybrid vehicle system, comprising:
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an engine including a cylinder; electric motor/generator coupled to a battery; an intake cam coupled to an intake valve; an intake throttled coupled to an intake manifold of the engine; and a controller with computer readable instructions for, in response to an operator request for a compression test, spinning the engine unfueled using the motor while fully advancing the intake cam and fully opening the intake throttle; monitoring a change in battery current during a compression stroke of the cylinder; estimating each of a cylinder compression torque and a cylinder compression pressure based on the monitored change; and indicating cylinder compression degradation based on the estimated cylinder compression pressure deviating from an expected cylinder compression pressure. - View Dependent Claims (20)
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Specification