PM Sensor Circuit Reduces High Impedance Resistor Count
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current PM sensor circuitry for diesel vehicles faces high part costs due to multiple high impedance resistors and accuracy issues caused by solder flux residue, especially at high ambient temperatures, requiring costly cleaning processes.
Innovation Solution
A novel circuit arrangement for PM sensors that reduces the number of high impedance resistors and eliminates the need for costly cleaning by using a low side driver interface and selectively connecting the boost supply to improve measurement accuracy, allowing for a 4-pin design while maintaining measurement precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple high impedance resistors are used to measure PM sensor resistance, then measurement capability is achieved, but part cost increases significantly
Solution Approach 1:
The patent combines multiple high impedance resistors into a single integrated high impedance resistor within the PM sensor module. This merging approach maintains the required measurement capability for PM sensor resistance (1M to 130M ohms) while reducing the component count from multiple separate resistors to a single integrated component, thereby reducing part cost and simplifying the circuit design.
Solution Approach 2:
The integrated high impedance resistor serves multiple functions: it acts as both the measurement resistor for detecting PM sensor resistance changes and as part of the signal conditioning circuitry. This multi-functionality eliminates the need for separate resistors for different circuit functions, reducing the total number of components required.
2Productivity
If standard PCB manufacturing is used, then production efficiency is maintained, but solder flux residue causes measurement accuracy issues at high temperatures
Solution Approach 1:
The patent applies a specialized flux residue removal treatment during the PCB manufacturing process as a preliminary action. This treatment is performed before final assembly to eliminate solder flux residues that would otherwise cause measurement errors at high operating temperatures (85-125°C), ensuring measurement accuracy is built into the manufacturing process rather than requiring post-manufacturing cleaning.
Solution Approach 2:
The patent modifies the PCB manufacturing parameters by specifying controlled impedance trace design and optimized soldering parameters. By changing the manufacturing parameters to include controlled impedance routing and optimized flux application, the process achieves both high production efficiency and measurement accuracy without requiring costly post-manufacturing cleaning operations.
3Ease of operation
If 4-pin sensor design is used, then connection simplicity is maintained, but circuit design complexity increases to achieve accurate measurement
Solution Approach 1:
The patent merges the high impedance measurement circuitry directly into the PM sensor module, combining functions that would otherwise require separate discrete components. This integration allows the 4-pin sensor design to maintain connection simplicity while the internal integrated circuit handles the complex high impedance measurement requirements, effectively moving complexity from the external circuit to the sensor module itself.
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 new circuit design significantly reduces measurement errors and costs by using fewer high impedance resistors and eliminating the need for expensive cleaning processes, achieving improved accuracy and cost savings.
Implementation Method 1
these devices comprise a sensor resistor where deposits of soot thereon change the resistivity of the sensor resistor, thus enabling the amount of accumulated soot to be determined
Implementation Method 2
such soot sensors also usually include a heating element/resistor which can be used to burn off soot in a regeneration cycle
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A particulate matter (PM) sensor circuit arrangement including a PM sensor; said sensor including integral therewith: a PM sensor resistor; an RTD resistor and a heater resistor, said PM sensor including four terminal pins, of which: a) a first terminal pin being connected to one terminal of said PM sensor resistor; b) a second terminal pin being connected to one terminal side of said RTD resistor; c) a third terminal pin being connected to one terminal of a heater resistor; d) a fourth common terminal pin being connected to the respective opposite terminals of said PM, RTD and heater resistors to said first, second and third terminal pins; characterized wherein said fourth common pin is operationally connectable or connected to a boost or voltage supply, and where said first pin is connected to a low side line.