Parallel Check Valve Oil Temperature Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing power transmission systems for vehicles face challenges in accurately measuring oil temperature inside a transaxle when the check valve in the electric oil pump is stuck, leading to impaired oil circulation and erroneous fault determination.
Innovation Solution
Incorporating a third check valve in parallel with the first check valve, with a larger flow resistance and lower minimum valve open pressure difference, to ensure oil circulation and allow accurate temperature measurement even when the first check valve is stuck, and utilizing an electronic control unit to determine fault conditions based on rotation speed and temperature thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single check valve is provided in the electric oil pump, then the structure is simple, but oil circulation is impeded when the check valve is stuck
Solution Approach 1:
The single check valve is segmented into two parallel check valves (first and second check valves). This segmentation allows oil to flow through alternative paths when one check valve fails, thereby maintaining oil circulation reliability while keeping the overall structure relatively simple.
Solution Approach 2:
A bypass passage with a third check valve is provided in advance as a backup path. When the first or second check valve becomes stuck, the third check valve automatically opens to allow oil circulation through the bypass passage, preventing complete circulation failure before it occurs.
2Measurement precision
If the oil temperature sensor is installed inside the transaxle case, then the temperature measurement is accurate under normal conditions, but the measurement becomes erroneous when the check valve is stuck
Solution Approach 1:
The bypass passage with the third check valve is prepared in advance to ensure continuous oil circulation to the transaxle case even when the primary check valves fail. This maintains the temperature measurement reliability by ensuring the sensor continuously receives oil for accurate temperature detection.
Solution Approach 2:
The bypass passage acts as an intermediary path that mediates between the electric oil pump and the transaxle case when the primary oil passage is blocked. This ensures continuous oil flow and maintains the functionality of the temperature sensor.
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 correct oil temperature detection and reduces erroneous fault determination by maintaining oil circulation and varying the electric oil pump's rotation speed, allowing for precise identification of stuck conditions and preventing unnecessary errors.
Implementation Method 1
a first check valve provided in a discharge oil passage of the electric oil pump; a second check valve provided in a discharge oil passage of the mechanical oil pump
Implementation Method 2
an oil temperature sensor provided at a merging point downstream of the first check valve and the second check valve
Data Source
AI summary
By providing an auxiliary check valve in parallel with a check valve installed in an electric oil pump, it is possible to measure an oil temperature even when the check valve is stuck. A flow resistance of an oil passage of the auxiliary check valve is set so as to be larger than that of the check valve, and a minimum valve open pressure difference of the auxiliary check valve is set so as to be smaller than that of the check valve. Thus, it is possible to further accurately measure an oil temperature and determine a fault. By using a rotation speed of the electric oil pump and an oil temperature in determining whether there is a fault in the electric oil pump or in the oil passage, it is possible to reduce the influence of variations, or the like, in measurement of a temperature sensor.