Common Rail Pressure Control with Sensor Failure Redundancy
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Solution Overview
Problem
Existing internal combustion engine common rail systems lack reliable fault safeguards, particularly in the event of rail pressure sensor failures, leading to undefined states and critical engine conditions due to the absence of effective redundancy mechanisms.
Innovation Solution
Implementing a method for open-loop and closed-loop control that activates emergency operating modes in case of sensor failures, utilizing a pressure control valve and passive pressure control valve to redirect fuel and maintain stable engine operation, with redundancy measures to ensure continued engine functionality and reduced emissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a closed-loop rail pressure control system with a suction throttle and pressure control valve is implemented, then rail pressure control precision is improved, but system complexity increases
Solution Approach 1:
The common rail system is divided into two independent rail systems (A-side and B-side), each with its own pressure control mechanism. This segmentation allows independent control and monitoring of each rail, improving overall system reliability and control precision without requiring a single complex centralized control system.
Solution Approach 2:
A feedback mechanism is implemented where the actual rail pressure is continuously monitored by a sensor and compared with the setpoint pressure. The control unit adjusts the suction throttle and pressure control valve based on the pressure deviation, creating a closed-loop control system that automatically maintains precise rail pressure control.
2Reliability
If redundancy mechanisms are added to safeguard against sensor failures, then system reliability is improved, but device complexity increases
Solution Approach 1:
The system incorporates a backup pressure control mechanism that can activate if the primary sensor or control mechanism fails. This beforehand cushioning ensures that if a sensor failure occurs, the system can switch to alternative control modes or use backup sensors, maintaining reliability without requiring complex real-time fault detection and switching systems.
Solution Approach 2:
The control system can adapt to sensor failures by changing operational parameters, such as switching between different pressure control modes or adjusting control strategies based on degraded sensor performance. This allows the system to maintain reliable operation under varying conditions without adding complex hardware redundancy.
3Stress or pressure
If the pressure control valve is activated to redirect fuel flow, then rail pressure is reduced, but fuel efficiency decreases
Solution Approach 1:
The pressure control valve is designed to provide precise, partial control of fuel flow rather than complete shutdown. By opening the valve only as much as necessary to reduce excessive rail pressure, the system achieves pressure control while minimizing fuel waste. The valve's position can be precisely adjusted to match the actual pressure deviation, avoiding excessive action that would waste fuel.
Solution Approach 2:
The system dynamically adjusts the pressure control valve opening based on real-time rail pressure measurements. When rail pressure is within the optimal range, the valve remains closed or partially closed to maintain fuel efficiency. When pressure exceeds the setpoint, the valve opens proportionally to reduce pressure, creating an optimized balance between pressure control and fuel consumption.
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 provides reliable closed-loop rail pressure control with redundancy, allowing for stable engine operation and minimal emission increases even when rail pressure sensors fail, ensuring safe and efficient engine performance.
Implementation Method 1
the suction throttle sets the admission cross section to the high-pressure pump and thus the volume of fuel delivered
Implementation Method 2
a pressure control valve on the high-pressure side by which pressure control valve volume flow is redirected from the rail into a fuel tank
Implementation Method 3
If the rail pressure rises above a critical value, for example, 2400 bars, the pressure control valve opens
Implementation Method 4
a high-pressure pump which delivers fuel to a common rail system
Implementation Method 5
the injectors for injecting the fuel into the combustion chambers of the internal combustion engine
Data Source
AI summary
Disclosed is a method for the control and regulation of an internal combustion engine (1), comprising an independent common rail system on the A-side and an independent common rail system on the B-side. During normal operation, the rail pressure (pCR(A), pCR(B)) is controlled in each common rail system via a low pressure-side suction throttle (4A, 4B) as the first pressure-adjusting element in a rail pressure control loop and, at the same time, the rail pressure (pCR(A), pCR(B)) is subjected to a rail pressure disturbance variable via a high pressure-side pressure control valve (11A, 11B) as a second pressure-adjusting element, by means of which a pressure control valve volume flow is redirected via the high pressure-side pressure control valve (11A, 11B) from the rail (6A, 6B) into a fuel tank (2). The method is characterized in that a first emergency operation is implemented for the common rail system in question when a defective rail pressure sensor (8A, 8B) and a non-defective pressure control valve (11A, 11B) have been detected in said common rail system, while a second emergency operation is implemented for the common rail system in question when a defective rail pressure sensor (8A, 8B) and simultaneously a defective pressure control valve (11A, 11B) have been detected in said common rail system, and wherein the normal operation is implemented for the other, non-defective common rail system.