A New, Low-cost, Spherical Joint System Design for
Automotive Applications

 

The Metal Textiles Spherical Joint System combines breakthrough innovation and global best-practices of the classic spring-loaded exhaust decoupler ball joint in a turnkey system to assure consistent superior performance for the life of the vehicle. Using a system approach, the proven durable exhaust ball joint technology has been optimized to provide near zero-leak performance at a fraction of the cost of bellows-based systems, while meeting the stringent durability and customer satisfaction needs of major automotive manufacturers worldwide.

The self-supporting exhaust decoupler design can support the weight of the exhaust system in either the vertical or horizontal direction, eliminating the need for additional hangers. In addition, the system displays stable, consistent, dynamic behavior throughout the life of the vehicle.

The Metal Textiles spherical-loaded joint system offers the following performance characteristics:

• Operating temperatures up to 700°C (flange surface)
• Less than 1.0 standard liters per minute leakage at pressures up to 34kPa when new
• Less than 2.0 standard liters per minute leakage at pressures up to 34kPa after vehicle durability tests
• Pipe outside diameters from 38 mm to 76 mm

The Metal Textiles spherical joint system is a complete “turnkey” spring-loaded ball joint for use in the exhaust systems of internal combustion engines. The system was developed to provide a joint with “near-zero” leakage performance in automotive exhaust systems, while acting as a:

• Exhaust decoupler to isolate the vibrations of the engine from the remainder of the exhaust system and the passenger compartment. This is extremely important in automobiles where any reduction in noise, vibration, and harshness (NVH) will improve ride quality.
• Pivot point to stop the exhaust system from moving when the engine exhibits large amplitude rolling motion. This is most important in front wheel drive (FWD) vehicles with transverse mounted engines. In these cases, the roll axis of the engine is perpendicular to the axis of the exhaust system. With no pivot point, the exhaust will slam into the vehicle underbody, or the ground, when the engine rolls upon gear changes and acceleration/deceleration.

Evolutionary Design for Spherical Joint System to Reduce Vibration and Enhance Product Quality

 

The Metal Textiles Spherical Joint System represents evolutionary refinements to the classic automotive ball joint combined with the best practices and a unique static sealing surface that results in a near-zero leak joint. These improvements include:

• Spring design, which minimizes loss of load due to spring relaxation.
• True spherical radius flange and offset seal radius leads to high sealing stress
• Spherical static sealing surface creates “wedging” effect, dramatically improving sealing ability
• Stamped flanges offer extremely smooth sealing surfaces, uninterrupted by weld seams typically found in flared pipes.

Sealing surfaces of the flanges resist oxidation, which could lead to increased leakage and squeak. Since traditional ball-joint-based systems only provide three rotational degrees of freedom (bending up-down, bending sideside, and twisting) the joint will not accommodate axial motion due to vibration or thermal expansion. The Metal Textiles automotive spherical joint system can eliminate this problem by using multiple joints in series. The combined effect of the multiple joints is a six-degree-of-freedom system. Due to this unique, double-joint configuration, thermal expansion and other axial movements can be easily accommodated.

Product Benefits

• Sealing Ability- The unique “turnkey” system design maximizes sealing ability and virtually eliminates leakage.
• Competitive Price- Lower cost alternative to flex couplings.
• Compact Size- Easier packaging. Minimizes heat loss.
• Self Supporting- Can support weight of exhaust systems in horizontal or vertical direction. Eliminates extra support hangers.
• Torsional Degree of Freedom- Capable of accommodating relative twist between upstream and downstream portions of the joint.
• Stable, Consistent Performance- Unlike flex exhaust decouplers, whose damping and support members change over time, this system displays consistent dynamic performance.