Gas Meter Crank Mechanism Temperature Compensation
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Solution Overview
Problem
Existing gas meter mechanisms fail to adequately compensate for temperature variations, leading to significant errors in volume readings, especially when exposed to outdoor temperatures that change with seasons, causing approximately 1% change in volume per 3K temperature change.
Innovation Solution
A crank mechanism for a gas meter with a rotary part and crank element connected to a temperature-dependent compensating element, featuring a rigid crank with arms of differing lengths and a bimetallic strip compensating element, allowing radial and tangential adjustments to correct for temperature-induced errors, with a resistance part limiting movement at lower temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional crank mechanism is used without temperature compensation, then the structure is simple, but measurement precision deteriorates due to temperature-induced volume reading errors
Solution Approach 1:
The patent employs bimetallic strips that exploit thermal expansion differences between two metal layers. When temperature changes, the bimetallic strip bends due to differential expansion/contraction, mechanically adjusting the crank element position to compensate for volume reading errors caused by temperature-induced gas density changes.
Solution Approach 2:
The invention changes the physical state and position parameters of the crank element through temperature-dependent bimetallic strips. The bimetallic strips transform temperature variations into mechanical displacement, dynamically adjusting the crank's radial and tangential positions to maintain measurement accuracy across different temperatures.
2Reliability
If bimetallic strips are used for temperature compensation, then temperature compensation capability is improved, but device complexity increases due to additional components
Solution Approach 1:
The patent merges the temperature compensation function with the existing crank mechanism structure. The bimetallic strips are integrated into the crank assembly, combining the compensation function with the motion transmission function in a unified structure, thereby reducing overall device complexity despite adding temperature compensation capability.
Solution Approach 2:
The bimetallic strips serve multiple functions: they provide temperature compensation, define the angular position of the swivel arm, and interact with the crank element to adjust both radial and tangential parameters. This multi-functionality reduces the need for separate compensation components.
3Measurement precision
If radial and tangential adjustments are implemented, then measurement precision is improved, but ease of operation deteriorates due to adjustment complexity
Solution Approach 1:
The bimetallic strips automatically perform the adjustment function in response to temperature changes. The system is self-regulating, with the bimetallic strips dynamically positioning the crank element without requiring external intervention or complex adjustment procedures, thereby maintaining ease of operation while achieving high measurement precision.
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
Effectively compensates for temperature changes by adjusting the crank element's position radially and tangentially, minimizing errors in gas volume measurements across varying temperatures, enhancing the operation of the compensating element and accommodating different gas meter designs and materials.
Implementation Method 1
a compensating element in the form of a bimetal helix, dependent on the temperature
Implementation Method 2
the compensating elements, the first element and the second element, are bimetallic strips with shapes resembling an incomplete letter 'U'
Data Source
Figure 1
AI summary
The invention relates to a crank mechanism for a gas meter with mechanical compensation of temperature, in particular for a bellows meter, comprising a rotary part (1), whose axis is the axis of rotation for a crank disc (2) seated thereon, and on the crank disc (2) there is placed a crank element (3) directly connected to a rigid crank (8) seated rotatably on the crank disc (2) via a rotary element (9), connected to a temperature-dependent compensating element (4), the crank mechanism being characterised in that the rigid crank (8) has a pair of arms, among which the arm (R) connected to the crank element (3) is longer than the arm (L) connected to the compensating element (4).