Piezoelectric Actuator Driving Device Voltage Stabilization
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Solution Overview
Problem
The accuracy of driving piezoelectric actuators in fuel injection systems is degraded due to variations in piezoelectric voltage, leading to inconsistent injector opening timing and fuel injection quantity, especially in diesel common rail systems where pressure fluctuations affect the actuator's expansion time.
Innovation Solution
A control unit alternately turns on and off the charging and discharging switches for the piezoelectric actuators, keeping the discharging switch on during the period between discharging and charging cycles to maintain a stable voltage and prevent voltage fluctuations, ensuring consistent actuator expansion and accurate fuel injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the discharging switch is turned off after discharging switching control is terminated, then the piezoelectric actuator can be quickly prepared for the next charging cycle, but the piezoelectric voltage fluctuates and drops, degrading driving accuracy
Solution Approach 1:
The discharging switch is kept ON in advance after discharging switching control is terminated, before the next charging switching control starts. This preliminary action maintains the piezoelectric voltage at a stable level (slightly higher than 0V) and prevents voltage fluctuations, ensuring accurate driving when the next charging cycle begins.
2Device complexity
If the piezoelectric voltage is allowed to fluctuate naturally after discharging, then the system operates with simpler control logic, but the expansion time and fuel injection quantity become inconsistent
Solution Approach 1:
The control unit monitors the piezoelectric voltage and uses feedback control to maintain it at a stable level. By keeping the discharging switch ON after discharging switching control is terminated, the system ensures the piezoelectric voltage remains slightly higher than 0V, preventing fluctuations and ensuring consistent expansion time and fuel injection quantity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the accuracy of piezoelectric actuator driving by maintaining a stable piezoelectric voltage, reducing variations in expansion time and ensuring precise fuel injection, thereby improving the performance of diesel common rail systems.
Implementation Method 1
A piezoelectric actuator, which expands and contracts by charging and discharging
Data Source
AI summary
A driving device for a piezoelectric actuator supplies charges and discharges the piezoelectric actuator through a charging switch and a discharging switch, respectively. The charging switch is repeatedly turned on and off thereby to charge and expand the piezoelectric actuator. The discharging switch is repeatedly turned on and off thereby to discharge and contract the piezoelectric actuator. The discharging switch is kept ON especially during a period from when the discharging switching control is terminated to when the charging switching control is started next. Thus, the piezoelectric voltage at the start of the next driving can be made substantially 0V.