Differential Pressure Measuring Device Span Adjustment

Solution Overview

Problem

Differential pressure measuring devices face challenges in accurately measuring fill levels in tanks when the liquid gas changes, as the hydrostatic pressure and hence the differential pressure change with different densities of gases, leading to incomplete utilization of the measurement range and requiring complex adjustments to maintain accuracy.

Innovation Solution

The differential pressure measuring device is designed such that the input and output elements are arranged to maintain the zero point position unchanged during span adjustments, allowing for easy adaptation to changes in maximum differential pressure without iterative zero point adjustments, by ensuring the first contact line is parallel to the actuating plane when the separating element is in the zero position.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the differential pressure measuring range is adapted to a change in maximum differential pressure by changing the span, then the measurement range can be adjusted to different gas densities, but the zero point position shifts requiring iterative adjustments

Engineering Contradiction:

Improvemeasurement range adaptationVSAvoidadjustment complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The adjusting device is separated into two independent functions: span adjustment and zero point adjustment. The span adjustment mechanism modifies the transmission ratio through the transmission mechanism, while the zero point adjustment is handled separately by the adjusting device that shifts the pointer train relative to the dial. This segmentation allows each function to be optimized independently and eliminates the interference between span and zero point adjustments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary zero point calibration by designing the pointer train to be pre-adjustable relative to the dial before span adjustment is performed. The adjusting device allows the pointer train to be positioned at the correct zero point location in advance, so that when span adjustment is later made, no iterative zero point corrections are needed. This preliminary action eliminates the need for repeated adjustments.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the span is changed to utilize the full dial range for different differential pressure measurements, then the display utilization is optimized, but the zero point drift occurs requiring iterative adjustments

Engineering Contradiction:

Improvedisplay utilizationVSAvoidadjustment time

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The adjusting device is separated into two independent functions: span adjustment and zero point adjustment. The span adjustment mechanism modifies the transmission ratio through the transmission mechanism, while the zero point adjustment is handled separately by the adjusting device that shifts the pointer train relative to the dial. This segmentation allows each function to be optimized independently and eliminates the interference between span and zero point adjustments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary zero point calibration by designing the pointer train to be pre-adjustable relative to the dial before span adjustment is performed. The adjusting device allows the pointer train to be positioned at the correct zero point location in advance, so that when span adjustment is later made, no iterative zero point corrections are needed. This preliminary action eliminates the need for repeated adjustments.

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If a complex adjusting device with spindle and bearing block is used to shift the output element, then the span can be adjusted steplessly, but the zero point adjustment becomes iterative and complex

Engineering Contradiction:

Improvespan adjustabilityVSAvoidadjusting device complexity

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The adjusting device is separated into two independent functions: span adjustment and zero point adjustment. The span adjustment mechanism modifies the transmission ratio through the transmission mechanism, while the zero point adjustment is handled separately by the adjusting device that shifts the pointer train relative to the dial. This segmentation allows each function to be optimized independently and eliminates the interference between span and zero point adjustments.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces an intermediary adjusting device that directly shifts the pointer train relative to the dial, bypassing the complex spindle and bearing block mechanism for zero point adjustment. This intermediary device provides a simple, direct adjustment path that eliminates the need for iterative adjustments through the original complex mechanism.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP1947438B1Differential pressure measuring device

Publication Date: 2011.12.28 WIKA ALEXANDER WIEGAND GMBH & CO KG

Figure 1~3
Figure 4~6
Figure 7~11

AI summary

Differential pressure measuring instrument has a measuring unit, a display unit and a transmission mechanism (18). The measuring unit has housings in which a chamber is formed, which is subdivided by a separating element into two pressure chambers. An input element of the display unit and an output element of the transmission mechanism is arranged relatively to each other in such a manner that a contact line runs parallel to a plain during the null position of the central section of the separating element.