Commercial Vehicle Disc Brake Sealing via Nested Bellows
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Solution Overview
Problem
The existing disc brake designs for commercial vehicles are complex and costly to produce, with a thick sheet metal closure cap required to accommodate an annular recess for the secondary seal, which increases material and weight costs.
Innovation Solution
A disc brake design that uses a dimensionally stable reinforcement ring embedded in an elastic plastic cuff of the bellows to securely hold and press the secondary seal against the contact surface, eliminating the need for an annular recess and allowing a thinner sheet metal closure cap, with sealing lips on the secondary seal providing a hermetic seal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an annular recess is introduced in the closure cap to accommodate the secondary seal, then the sealing reliability is improved, but the sheet metal thickness must be increased to 1.75 mm, which increases material costs and weight
Solution Approach 1:
The secondary seal is nested within the bellows structure, specifically positioned in the cuff region of the bellows. This eliminates the need for a separate annular recess in the closure cap, as the bellows structure itself provides the housing for the secondary seal, thereby reducing material requirements and weight.
Solution Approach 2:
The bellows structure serves multiple functions: it provides the primary sealing arrangement, houses the secondary seal, and eliminates the need for a separate annular recess feature in the closure cap. This multi-functionality reduces the overall complexity and material requirements of the closure cap design.
2Reliability
If an annular recess is introduced in the closure cap to accommodate the secondary seal, then the sealing reliability is improved, but the production complexity and cost increase due to the pronounced collar and indentation requirements
Solution Approach 1:
The secondary seal is nested within the bellows structure, eliminating the need for a complex annular recess and pronounced collar in the closure cap. This simplifies the closure cap to a basic stamped/formed part that is easier and more cost-effective to produce.
Solution Approach 2:
The sealing function previously requiring a complex annular recess and pronounced collar is extracted from the closure cap and relocated to the bellows structure. This extraction simplifies the closure cap design and manufacturing process while maintaining the secondary sealing function.
3Strength
If the sheet metal thickness is increased to 1.75 mm to accommodate the annular recess, then the structural strength is improved, but the material costs and weight increase
Solution Approach 1:
The secondary seal is nested within the bellows structure, eliminating the need for a thick 1.75 mm sheet metal closure cap with annular recess. The thinner sheet metal is sufficient because the bellows structure provides the housing for the secondary seal, thereby reducing material usage and weight while maintaining structural integrity.
4Strength
If the sheet metal thickness is increased to 1.75 mm to accommodate the annular recess, then the structural strength is improved, but the material costs increase
Solution Approach 1:
The secondary seal is nested within the bellows structure, eliminating the need for a thick 1.75 mm sheet metal closure cap. The thinner sheet metal is sufficient because the bellows structure provides the housing for the secondary seal, thereby reducing material quantity and costs.
Solution Approach 2:
The bellows structure serves multiple functions including housing the secondary seal, which eliminates the need for additional sheet metal features like annular recesses. This multi-functionality reduces the total quantity of sheet metal required while maintaining structural strength.
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 design simplifies production, reduces material costs, and minimizes weight by allowing a thinner sheet metal thickness, optimizing the disc brake's operation and cost-effectiveness.
Implementation Method 1
the bellows resting frictionally on the contact surface of the collar
Implementation Method 2
the reinforcement ring projects out of the cuff in the direction of the secondary seal and rests with its free end on the secondary seal and presses it against the contact surface
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a disc brake comprising a brake caliper in which two brake pads are arranged that function so as to be pressable against a brake disc, wherein at least one action-side brake pad of the brake pads can be actuated by a brake application device via at least one actuating spindle, which is held in a bridge in an axially adjustable manner, and the actuating spindle is guided through an opening of a closure cover (1) that closes a receiving chamber of the brake caliper. In order to seal the receiving chamber, a seal assembly is provided in the region of the opening, said seal assembly comprising a bellows (3) which rests against the actuating spindle or a pressure piece connected thereto, and a secondary seal (4) is also provided that is arranged concentrically relative to the bellows (3) and, like the bellows (3), is held against a stepped collar (2) delimiting the opening of the closure cover (1) by means of an axially aligned circumferential contact surface (7) and a support surface (6) which is angled relative to the contact surface, which is aligned radially inwards, and on which a circumferential sealing bead (8) of the secondary seal (4) rests. The disc brake is designed such that the sealing bead (8) is arranged between a dimensionally stable reinforcement ring (10) of the bellows (3) and the contact surface (7) in the radial direction.