Engine Starting Strategy Avoiding Resonant Frequency
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Solution Overview
Problem
Engine-driven machines experience resonance at lower start-up speeds due to inertial forces and parasitic loads, which can cause damage to mechanical components, especially in cold weather when engines struggle to overcome resonant frequency speeds.
Innovation Solution
Implementing an engine starting strategy that involves disengaging the clutch to allow the engine to start independently of the transmission and auxiliary mechanisms, and using a hybrid motor to rotate these components until the engine speed exceeds the resonant frequency, thereby avoiding high torque amplitudes and facilitating smooth engagement when safe speeds are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the engine starts while connected to the transmission and auxiliary mechanisms, then the engine must overcome large inertial forces and parasitic loads, but this causes the engine to stall or fail to reach operating speed, especially in cold weather
Solution Approach 1:
The patent divides the starting process into two distinct phases: Phase 1 where the engine starts independently with the clutch disengaged (separating the engine from the transmission and auxiliary mechanisms), and Phase 2 where the clutch is engaged to connect the engine to the powertrain components. This segmentation allows the engine to overcome the contradiction by starting without bearing the full inertial and parasitic loads.
Solution Approach 2:
The patent applies preliminary action by having the hybrid motor rotate the transmission and auxiliary mechanisms before engine start-up, or by pre-positioning the clutch in a disengaged state. This preliminary action reduces the inertial forces and parasitic loads that the engine would otherwise need to overcome during starting, thereby improving start-up reliability.
2Productivity
If the clutch is engaged at low engine speeds, then the transmission and auxiliary mechanisms can be rotated, but this subjects the powertrain components to resonant frequency vibrations and high torque amplitudes that can cause mechanical damage
Solution Approach 1:
The patent applies the skipping principle by rapidly accelerating the engine through the resonant frequency range rather than allowing it to linger at dangerous speeds. The control system monitors engine speed and quickly transitions through the critical resonant zones, minimizing the duration of exposure to harmful vibrations and torque amplitudes, thus protecting powertrain components while maintaining start-up efficiency.
Solution Approach 2:
The patent employs feedback control by continuously monitoring engine speed and comparing it against predetermined safe operating ranges. When the engine approaches resonant frequencies, the control system adjusts clutch engagement timing and hybrid motor assistance to keep the engine speed within safe boundaries, thereby avoiding harmful vibrations while maintaining productive start-up operation.
3Adaptability or versatility
If the engine is designed to operate above resonant frequencies, then normal operating range can be maintained, but the engine cannot successfully start up through the resonant frequency speeds, particularly in cold weather conditions
Solution Approach 1:
The patent introduces the clutch and hybrid motor as intermediary devices that mediate between the engine and the powertrain components during start-up. The clutch acts as a controlled connection/disconnection mechanism, while the hybrid motor provides additional torque assistance. These intermediaries enable the engine to start successfully by temporarily decoupling it from the heavy loads, then smoothly connecting it once the engine is running above resonant frequencies, thus maintaining both adaptability and cold weather start-up capability.
Data Source
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AI summary
A machine (100) comprising a clutch (112) that engages and disengages. The machine includes an engine (102) operable at various engine speeds including a resonant frequency engine speed, and a transmission (114) connected to the engine through the clutch. The engine applies power to the transmission when the clutch is engaged, and the engine does not apply power to the transmission when the clutch is disengaged. The machine comprises an engine starter (104) that applies power to the engine, and an electronic control module (124) that controls the clutch to disengage when the engine starter applies power to the engine and to engage after the engine speed exceeds the resonant frequency engine speed.