High-Pressure Fuel Pump Drive Circuit Current Decay
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional high-pressure fuel pump drive circuits experience prolonged fall times of electric current, leading to reduced controllability and stability of fuel pressure, especially at increased engine rotational speeds, and generate excessive heat due to inefficient energy consumption.
Innovation Solution
A high-pressure fuel pump drive circuit design featuring a first and second switching element connected in series with a solenoid coil, a flywheel diode in parallel with the solenoid and second switching element, and a Zener diode connected to the power source, creating a feedback circuit that accelerates the fall time of electric current and reduces heat generation by utilizing the Zener diode to consume energy when the first switching element is OFF and the second is ON.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional flywheel diode circuit is used to protect against voltage spikes, then the solenoid coil is protected from damage, but the fall time of electric current is prolonged and fuel pressure stability deteriorates
Solution Approach 1:
The circuit is segmented into multiple paths: the main flywheel diode path for protection and a parallel Zener diode path for accelerated current decay. This segmentation allows the system to handle different operational requirements simultaneously - protection during normal operation and rapid decay when needed
Solution Approach 2:
The Zener diode acts as an intermediary component that provides an alternative current path with controlled impedance. When activated, it mediates the current decay process by providing a lower impedance path than the flywheel diode alone, thereby accelerating current fall time while still protecting the circuit
2Productivity
If the MOSFET switching cycle is made faster to improve controllability, then the voltage developed at the solenoid coil ends is reduced, but the fall time of electric current becomes prolonged when MOSFET is kept OFF
Solution Approach 1:
The Zener diode provides a feedback mechanism that senses the current state through its voltage characteristics and automatically adjusts the current path accordingly. When current needs to decay rapidly, the Zener diode's voltage characteristics create a feedback loop that accelerates the decay process without requiring additional control signals
3Duration of action of moving object
If a Zener diode is added to shorten current fall time, then the fuel pressure stability is improved, but the device complexity increases and manufacturing cost rises
Solution Approach 1:
The Zener diode is a low-cost, simple semiconductor component that provides the desired function of accelerated current decay. By using this inexpensive component rather than complex control circuits or expensive specialized devices, the solution achieves improved current fall time while minimizing the increase in device complexity and manufacturing cost
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
The solution effectively shortens the fall time of electric current and minimizes heat generation, enhancing the controllability and stability of the high-pressure fuel pump, even at higher engine speeds, while reducing manufacturing costs by employing a clamp Zener diode-attached IPD and current-detecting circuits for improved accuracy.
Implementation Method 1
electromagnetic energy is caused to accumulate in the solenoid coil 2 due to this electric current IL
Implementation Method 2
a power to force electric current to flow in the direction to inhibit any changes of magnetic flux is acted thereon due to the self-induction electromotive force (e=L*ΔI/Δt) by the electromagnetic energy
Implementation Method 3
the flywheel diode consumes an energy of the solenoid coil when the first switching element is turned OFF during a period in which the second switching element is ON
Implementation Method 4
a Zener diode connected with the power source is disposed parallel with the second switching element... the Zener diode to consume energy when the first switching element is OFF and the second is ON
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
There is provided a high-pressure fuel pump drive circuit for manipulating the electric current to be passed to a solenoid coil for controlling a high-pressure pump. This circuit is characterized in that a first switching element, the solenoid coil and a second switching element are connected in series with each other in a rout from a source voltage side to the ground side, that a flywheel diode for passing electric current to a power source is disposed parallel with the solenoid and with the first switching element, and that a Zener diode connected with the power source is disposed parallel with the second switching element, wherein a counter electromotive force to be developed at the opposite ends of solenoid coil on the occasion when the second switching element is changed from ON to OFF is consumed by the flywheel diode provided that the first switching element is in a state of ON, and the counter electromotive force is more rapidly consumed by the Zener diode provided that the first switching element is turned OFF.