Belt Drive Tensioner with Nested Spring and Arm
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Solution Overview
Problem
Existing tensioning devices for belt drives with endlessly circulating belts and electric machines have limitations in tilting stability and spring characteristics due to constrained sliding bearing distances and installation space, which affect the effective tensioning and decoupling of torque in internal combustion engine starter generators.
Innovation Solution
The tensioning device employs two helical compression springs connected in series, with an intermediate piece allowing a floating sliding bearing point and increased spring length, and a circular arc-shaped tensioning arm design, utilizing the spring interior as installation space to enhance tilting stability and spring characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the sliding bearing distance is increased to improve tilting stability of the tensioning arm, then the tilting stability is improved, but the installation space requirement increases
Solution Approach 1:
The tensioning arm is designed with a pin projection that passes through the helical compression spring, utilizing the spring's interior space as installation space for the tensioning arm. This nesting arrangement allows the sliding bearing point to be positioned farther inside the tensioner housing, increasing the sliding bearing distance and improving tilting stability without increasing the overall installation space footprint.
2Reliability
If the spring component length is increased to improve spring characteristics with flat spring characteristic curve, then the spring characteristics are improved, but the installation space requirement increases
Solution Approach 1:
The helical compression spring is positioned such that its interior space accommodates the pin projection of the tensioning arm. This nesting allows the spring to achieve a longer effective length for improved spring characteristics (flat spring characteristic curve with large travel) while containing its overall envelope within the available installation space of the tensioner housing.
Solution Approach 2:
The spring component is arranged in a configuration that utilizes three-dimensional space efficiently. By positioning the spring such that its length extends in one dimension while its diameter is constrained in another, and using its interior space for the tensioning arm bearing, the design achieves improved spring characteristics without proportionally increasing the installation space footprint.
3Stability of the object's composition
If the tensioning arm guide length is increased to reduce tilting caused by sliding bearing play, then the tilting stability is improved, but the device complexity increases
Solution Approach 1:
The pin projection of the tensioning arm passes through the helical compression spring and is supported in a floating manner in the intermediate piece. This nested arrangement through the spring interior provides an extended sliding bearing distance for stabilizing the tensioning arm against tilting, while using existing components (spring and intermediate piece) rather than adding separate guiding structures, thereby avoiding increased device complexity.
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
This configuration increases the sliding bearing distance and effective spring length, providing a more stable and efficient tensioning mechanism with improved spring characteristics for alternating torque transmission and decoupling in belt drives.
Implementation Method 1
a spring component that generates the biasing force and whose spring ends are clamped between the tensioner housing on one side and the tensioning arm on the other side
Data Source
AI summary
A clamping device (2) for a starter generator belt drive of an internal combustion engine. The clamping device includes a tensioner housing (8), a tensioning arm (17) mounted movably therein, and two idlers (6, 7), one of which is mounted to the tensioning arm and the other of which is mounted to the tensioner housing (8) in a stationary manner. A spring component which generates the pre-load force includes two helical compression springs (20a, 20b) connected in series, the facing spring ends (23a, 23b) of which are separated by an intermediate piece (24) mounted in the tensioner housing in a sliding manner. The tensioning arm has a pin projection (28), which extends through the helical compression springs running inside the tensioning arm and which is mounted in the intermediate piece in a sliding manner.