Balance Spring Temperature Compensation With Variable Preload
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Solution Overview
Problem
Mechanical watches face precision issues due to frequency variations caused by external parameters such as temperature, pressure, humidity, and gravity, which affect the resonator's frequency and lead to time measurement errors.
Innovation Solution
A horological regulating member with a balance spring and temperature-compensation means, featuring a resilient device that adjusts stiffness based on temperature changes through preloading means, comprising a resilient element and a bimetallic attachment to modify the force or torque exerted on the resilient element, thereby adjusting the resonator's rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional balance spring is used without temperature compensation, then the structure is simple, but the time measurement precision deteriorates due to frequency variations caused by temperature changes
Solution Approach 1:
The resilient element is integrated within the balance spring structure, with the outer end of the resilient element positioned at the center of the balance spring's inner turns. This nested configuration allows the temperature compensation mechanism to be embedded within the existing resonator structure without significantly increasing overall complexity.
Solution Approach 2:
The resilient element's stiffness parameter is made variable through temperature-dependent material properties or structural design. As temperature changes, the stiffness of the resilient element automatically adjusts to compensate for frequency variations in the balance spring, thereby maintaining measurement precision without requiring complex active control systems.
2Measurement precision
If temperature compensation means is added to the balance spring, then time measurement precision improves, but the device complexity increases
Solution Approach 1:
The resilient element is designed to automatically adjust its stiffness in response to temperature changes without requiring external control systems. The element's own structural or material properties enable it to self-regulate and compensate for temperature effects on the balance spring frequency, thereby improving precision while minimizing added complexity.
Solution Approach 2:
The resilient element utilizes thermal expansion or contraction of its material to automatically adjust its mechanical properties. As temperature varies, the element's dimensions and stiffness change in a controlled manner that compensates for temperature-induced frequency drift in the balance spring, providing passive temperature compensation.
3Measurement precision
If the resilient element stiffness is made variable to compensate for temperature, then the rate precision is maintained, but the control mechanism becomes more complex
Solution Approach 1:
The resilient element inherently possesses temperature-dependent stiffness characteristics through its material composition or structural design. This self-regulating property eliminates the need for complex external control mechanisms, sensors, or actuators to adjust stiffness, while still achieving precise rate compensation across temperature variations.
Solution Approach 2:
The resilient element may be constructed from composite materials with tailored thermal-mechanical properties. By combining materials with different thermal expansion coefficients or stiffness-temperature characteristics, the element achieves automatic stiffness modulation with temperature while maintaining a simple, integration-friendly structure.
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
Maintains a precise rate despite significant temperature changes by finely regulating the resonator's frequency, ensuring high precision in timekeeping.
Implementation Method 1
preloading means for applying a variable force or torque to the resilient element as a function of the temperature
Implementation Method 2
resilient device comprising a resilient element connecting the outer end to a first support that is stationary relative to the horological movement
Data Source
AI summary
A regulating member (1) for a horological movement including an oscillating weight, for example a balance, and a balance spring including a flexible strip (2) wound about itself in a plurality of turns, the strip (2) having a predefined rigidity to allow the oscillating weight to undergo a rotary oscillatory motion, the strip (2) including an outer end (9), wherein the regulating member (1, 10) includes a temperature-compensating resilient device configured to adapt the stiffness thereof as a function of the temperature to compensate for the effect of temperature on the regulating member (1, 10), the resilient device including a resilient element (5) connecting the outer end (9) to a first support (7) that is stationary relative to the horological movement, as well as preloading means (6) for applying a variable force or torque to the resilient element (5) as a function of the temperature.