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The Metex Spherical
Joint System combines breakthrough innovation and global best-practices
of the classic spring-loaded ball joint in a turnkey system to
assure consistent superior performance for the life of the vehicle.
Using a system approach, the proven durable 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 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 Metex 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 Metex 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:
- Decoupling point 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 Systems to
Reduce Vibration and Enhance Product Quality
The Metex 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 Metex 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.
Metex factory-trained application engineers are always available to assist
you with your special applications, either by phone or at your site.
Mechanical Oscillator Test
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
couplings, whose damping
and support members
change over time, this system
displays consistent
dynamic performance.
Durability Testing
High-Temperature Oscillator Testing
- Mechanical sinusoidal inputs up to
10 Hz
- Hydraulic sinusoidal, square, and
triangle wave inputs up to 45 Hz
- Gas temperatures up to 1200°C
High-Temperature Corrosion
Oscillator Testing
- As above, with engine-roll simulation,
with automatic salt spray or mud/salt
solution
On Vehicle Testing
- High mileage dedicated fleet testing
Engine-Roll Simulation
- Engine and manifold roll movements
with full or partial exhaust system
- Gas temperatures up to 1200°C
- Automatic salt spray or mud/salt
solution
Noise Screening Testing
- Hand oscillator evaluations
- Room temperature screening
- High temperature screening
Leak Testing
- Static measurements
- Dynamic measurements
Average leakage values for spherical joint system prior to durability testing. (34 kPa internal pressure)
Average leakage values for spherical joint system after durability testing. (34 kPa internal pressure)
High-Temperature Durability
- Total of 555,000 cycles for a test time
of approximately 20 hours
- The test is broken down into 10 blocks
with each block containing 50,000
cycles +/– 2° at 8 Hz/5,000 cycles +/–
4° at 6 Hz/500 cycles +/– 6° at 4 Hz
- The test temperature on the outer
face surface is 600-625° C, with one
out of every five blocks run at room
temperature
High-temperature durability test of Spherical Joint System
High-Temperature Corrosion Durability
- This test consists of oscillating a joint
+/– 3° for 500,000 cycles between
room temperature and an operating
temperature
- During ramp up and ramp down of
the temperature cycles, the oscillating
frequency will be 2.5 Hz
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During the steady state portion, the
oscillating frequency is 8 Hz
- A salt solution is applied to the joint for
15 seconds every 15 minutes
- The profiles shown are repeated
twice for a test time of approximately
20 hours
Test frequency for high-temperature corrosion durability test
Noise Screening & Evaluation
Subjective Noise Screening Performed During Testing
| LEVEL |
|
DESCRIPTION |
| 0.0 |
|
No noise |
| 0.5 |
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Noticeable noise is confirmed by using a tube |
| 1.0 |
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Noticeable noise is confirmed within 200 mm from joint |
| 2.0 |
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Noticeable noise is confirmed within 1 m from joint |
| 3.0 |
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Noticeable noise is confirmed with 3 m from joint |
| 4.0 |
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Noticeable noise is confirmed within 10 m from joint |
| 5.0 |
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Noticeable noise is confirmed with 20 m from joint |
Temperature profile for high-temperature corrosion durability test
Typical noise levels recorded during durability testing
US Patent 5,683,119 and Foreign Patents
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