Partial Bearing Surface Balancer Shaft Weight Reduction
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Solution Overview
Problem
Conventional balancer shafts for multi-cylinder engines are weight-optimized but struggle to further reduce moving masses as engine speeds increase, necessitating a solution that maintains balance compensation while minimizing weight.
Innovation Solution
The balancer shaft features a bearing with a radial running surface that extends only partially over the circumference, allowing for significant weight reduction at the bearing point and enabling the reduction of unbalanced weight sections, while maintaining balance compensation through a configuration that supports centrifugal forces and retains a long service life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the bearing point is designed with a running surface extending only partially over the circumference, then the weight of the bearing point is significantly reduced, but the reliability of the bearing function may be compromised
Solution Approach 1:
The bearing point is designed with a running surface that extends only partially over the circumference (between 180° and 359°), concentrating the bearing function in the critical load-bearing area while reducing material in non-critical areas. This local differentiation maintains reliability where needed while achieving weight reduction overall.
Solution Approach 2:
Instead of providing a full 360° running surface, the invention uses a partial running surface covering only the essential arc (180°-359°). This partial action is sufficient to maintain bearing function during operation while significantly reducing the amount of material required.
2Weight of moving object
If material is reduced at the bearing point to achieve weight savings, then the weight decreases, but the service life of the bearing may be affected
Solution Approach 1:
The running surface is concentrated in the arc where load-bearing is critical (180° to 359°), ensuring adequate material presence and lubrication in the high-stress zones that determine service life, while reducing material only in areas that do not contribute to bearing durability.
3Weight of moving object
If the running surface extends only partially over the circumference, then weight is reduced, but the bearing point may become insufficient to support centrifugal forces
Solution Approach 1:
The running surface is strategically positioned to cover the arc (180° to 359°) where centrifugal forces act most critically during rotation. This ensures that the bearing point has sufficient material and contact area exactly where the centrifugal loads are applied, while reducing material elsewhere.
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 achieves a weight saving of 20 to 40% compared to conventional balancer shafts while ensuring the bearing function is retained, with a bearing life that remains unaffected by partial material reduction, and allows for efficient lubrication and stress absorption.
Implementation Method 1
The running surface, which extends partially over the circumference of the bearing point, corresponds to the circumferential section of the balancer shaft, in which the unbalanced weight sections are provided. This allows the resulting centrifugal force to be in an area of the bearing point that is also encompassed by the partial running surface when the balancing shaft rotates
Data Source
AI summary
The invention relates to a balance shaft for a multi-cylinder engine with at least one unbalance weight section (21, 22; 23, 24) and at least one bearing point (16, 17), wherein the at least one unbalance weight section (21, 22; 23, 24) is assigned to a bearing point (16, 17), wherein the bearing point (16, 17) has a radial running surface (18) which extends only partially over a circumference of the bearing point (16, 17) and a centrifugal force resulting from rotation of the balance shaft (11) lies within a region of the bearing point (16, 17) formed by the running surface (18) which extends partially over the circumference of the bearing point (16, 17), and wherein the bearing point (16, 17) comprises a running ring (39) which surrounds the partially formed running surface (18) of the bearing point (16, 17).