BWI Group passive dampers are derived from a century-long heritage of suspension technology development and manufacture carried out first by Delco Products Division of General Motors Corporation, later by Delphi Automotive, and now by BWI Group. Product portfolio ranges from dampers for all sizes of passenger cars through performance and luxury cars to heavy SUV’s and delivery vans.
BWI Group manufactures passive dampers for OEM market in Europe, Asia and North America, developing the core technology in one major technical center in Europe (Kracow, Poland) and working on applications in customer regions.
BWI Groups product development capabilities include:
BWI Group passive dampers technology is based on a Bill of Design (BoD) and Bill of Process (BoP) principle combined with continuous improvement and an innovative approach to new product functionalities.
BoD/BoP collects all proven technologies and lessons learned throughout years of manufacture into a set of standardized, reliable and economical design and process solutions.
BWI Group delivers the whole range of passive damper design variants: shock absorbers, coil-over-shock absorbers and McPherson struts in twin- and monotube execution. Piston rod size for twintube dampers ranges from 10 to 28 mm, while main valve sizes extend from 20 to 40 mm. For monotube dampers, piston rod sizes range from 11 mm to 18 mm combined with 36 mm or 46 mm valves. Standard solutions may also incorporate rebound energy management devices like steel or plastic rebound springs and bumpers.
BWI Group focuses on refining damper performance in terms of NVH behaviour and friction reduction. As a result, BoD is regularly updated with noise-reducing features and low friction solutions.
Apart from standard passive damper technology, BWI Group offers innovative solutions to address or exceed evolving market expectations:
BWI dampers are appreciated by vehicle manufacturers for:
Design aimed at reduction of maximum force transmitted to vehicle body in compression stroke and improvement of vehicle comfort on severe impacts without deterioration of body control and handling. Built into the compression side of the piston valve. Ensures practically flat force-velocity curve in compression for piston rod speeds over 0.7 m/s.
Design ensures steep increase of damping forces in compression stroke for piston rod velocities exceeding 1,5 m/s. Features adjustable switching point, damping force gain and rate. Can be added to base valve, piston valve or both valves.
Ensures additional protection of other suspensions components at high compression impacts (bad roads) by dissipating excess of impact energy inside the damper. Contributes to improved vehicle handling in off-road conditions.
Monotube damper with additional compression valve
Monotube damper with additional compression valve between piston and gas cup helps reduce internal gas pressure and achieve twintube performance in monotube packaging. Potential 30%? damper weight reduction and enhanced performance (combining advantages of twin and monotubes).
Hydraulic Rebound Stop (HRS) for end of rebound stroke energy management system
The aim of the Hydraulic Rebound Stop is to improve ride quality throughout the damper stroke while eliminating the impact and topping noise at fully extended position. End of stroke damping generated in HRS dissipates the energy which normally appears as a spike of energy when transferred through conventional rebound stops.
Hydraulic Rebound Stop features:
Hydraulic Rebound Stop is compatible with internal rebound springs.
First production implementation in 2011.
Hydraulic Compression Stop (HCS) for end of compression stroke energy management system
Hydraulic Compression Stop is an hydraulic system which replaces conventional hard bump stops with hydraulic cushion. The peak force transmitted to the vehicle body from the suspension can be reduced because energy will be dissipated as HCS damping. Because of this, the vehicle body structure can be lighter due to lower strength and stiffness requirements for the same standard of refinement and durability. Moreover, HCS is not only more tuneable than traditional bump stops, leading to better vehicle dynamic performance, but it also improves noise, vibration and harshness (NVH). HCS improves occupant comfort and chassis refinement while ensuring that a heavily laden vehicle that is more likely to bottom its suspension can do so without transmitting damaging loads into the body structure.
Due to different expectations to the level of compression damping force increase in the HCS system, two solutions are available:
A direct way to reduce weight is to replace currently used materials (all grades of steel) with lightweight equivalents like aluminium or composite materials.
Even greater weight saving may be achieved with composite materials. For structural elements, lower mechanical properties may be offset by complex plastic-molded geometry. Strength and stiffness is built through structural design instead of material properties.
Available composite material applications:
Tailored component shape and properties
Objective: remove unnecessary material without loss of damper performance or fatigue life.
BWI Group offers these products in the area of tailored component shape and properties:
Hollow piston rod
Piston rod size is primarily determined based upon the expected level of lateral force (bending moments). The majority of the stresses are supported by extreme fibers of the rod, leading to the potential to replace the solid piston rod structure by a tube without significant loss of strength or stiffness. Production technology is available in a variety of diameters from 18mm to 25mm, along with various tube thicknesses.
One piece knuckle bracket
Conventional strut clevis bracket design assumes an insert and outer shell, resistance welded together. The optimized shape consists of a reinforced insert, providing significant weight reduction and better stiffness. First production implementation in 2002.
Reservoir tube with variable wall thickness
Strut applications are exposed to significant level of bending moments which are the highest at the mounting interface (knuckle). The conventional approach is to deliver a straight tube that fulfils the strength requirement but carries overdesign in the areas further away from the mounting. This novel approach is to deliver an outer tube where strain is equal along the tube’s length – tailored properties of the final tube deliver strength relevant to the stress level;
Mass reduction up to 20% – depending on application (length of clamping area, diameter, wall thickness in clamp area).
Technology developed and implemented in-house, first production implementation in 2013.