Double Pipe Breather Pressure Failure Detection
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Solution Overview
Problem
Existing failure determination devices for internal combustion engine breather pipes struggle to accurately and quickly detect small failures, as they rely on air-fuel ratio changes and require state changes between supercharged and not-supercharged states, leading to delayed or inaccurate failure detection.
Innovation Solution
A failure determination device using a double pipe breather pipe system with an inner and outer pipe, where the enclosed space is communicated with the intake passage downstream of the supercharger, employing pressure sensors to detect breather outer-pipe pressure and intake pressure, and setting a determination threshold based on intake pressure to quickly identify pipe failures by comparing pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fuel correction amount is used to determine breather pipe failure, then failure detection is possible, but detection accuracy deteriorates when failure degree is small
Solution Approach 1:
The patent introduces an intermediary communication passage that connects the enclosed space between inner and outer pipes to the intake passage downstream of the supercharger. This allows pressure changes in the breather pipe to be transmitted to a location where they can be reliably detected, serving as a mediator between the breather pipe system and the detection mechanism.
Solution Approach 2:
The patent replaces the chemical/measurement-based fuel correction method with a direct pressure detection method. By using pressure sensors to detect pressure changes in the enclosed space, the system achieves more precise and immediate failure detection without relying on indirect fuel consumption measurements.
2Reliability
If sum of fuel correction amounts in supercharged and not-supercharged states is used, then failure determination is possible, but response time increases due to state change requirement
Solution Approach 1:
The communication passage is pre-established between the enclosed space and the downstream intake passage, allowing pressure changes to be immediately transmitted and detected without requiring state changes. The system is prepared in advance to detect failures at any operating condition.
Solution Approach 2:
Instead of changing engine states to detect failures, the patent inverts the approach by detecting pressure changes that occur naturally during normal operation. The detection method works during both supercharged and non-supercharged states simultaneously, eliminating the need for state transitions.
3Measurement precision
If double pipe breather pipe with enclosed space is used, then failure detection precision is improved, but device complexity increases
Solution Approach 1:
The outer pipe of the double pipe structure serves multiple functions: it provides structural support, creates the enclosed detection space, and acts as a barrier to isolate pressure changes. This multi-functionality reduces the need for separate components and justifies the added structural element.
Solution Approach 2:
The enclosed space between the inner and outer pipes acts as an intermediary chamber that isolates and amplifies pressure changes from the breather pipe. This mediator space allows small pressure changes to be detected more reliably before being transmitted to the downstream intake passage.
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
Enables rapid and accurate detection of breather pipe failures by comparing breather outer-pipe pressure with a determination threshold, effectively preventing false determinations and ensuring timely failure identification regardless of atmospheric pressure changes.
Implementation Method 1
a breather outer-pipe pressure detection unit that detects pressure in the enclosed space between the inner pipe and the outer pipe
Implementation Method 2
a communication passage that communicates the enclosed space between the inner pipe and the outer pipe and the downstream side of the supercharger with each other
Data Source
AI summary
In a failure determination device for an internal combustion engine equipped with a supercharger, the failure determination device determining a failure of a breather pipe that is connected between a crankcase and an intake passage at a position on an upstream side of the supercharger, the breather pipe is constituted by a double pipe including an inner pipe and an outer pipe, a communication passage communicates an enclosed space between the inner pipe and the outer pipe of the breather pipe with a portion of the intake passage on a downstream side of the supercharger. When the detected breather outer-pipe gauge pressure is higher than or equal to a determination threshold that is set in accordance with detected intake gauge pressure, the failure determination device determines that the breather pipe is failed.