Types of vehicle shock absorbers

Most vehicle shock absorbers are either twin-tube or single-tube types, with some variations on these themes.

Double tube

Basic double barrel:

Also known as a "twin tube" shock absorber, the unit consists of two nested cylindrical tubes, an inner tube called the "working tube" or "pressure tube", and an outer tube called the "reserve tube" Tube. At the bottom of the internal device is a compression valve or foot valve. When the piston is forced up or down due to a bump in the road, hydraulic fluid moves between the different chambers through small holes or "holes" in the piston and valves, converting the "shock" energy into heat, which must then be dissipated. scattered.

Double tube inflation:

Known as the "air chamber twin" or similarly named design, this variation represented a significant advance over the basic twin-pipe form.Its overall construction is very similar to the twin pipe, but with the addition of low pressure nitrogen in the stock pipe.The result of this change is a significant reduction in "foaming" or "aeration", an undesirable consequence of twin tube overheating and failure, manifested as foaming hydraulic fluid dripping from the assembly.Twin-tube gas-filled shock absorbers represent the vast majority of original modern vehicle suspension arrangements.

Position sensitive damping:

Often abbreviated to "PSD," this design is another evolution of the twin-tube shock absorber.In the PSD shock absorber, which still consists of two nested tubes and still contains nitrogen, an additional set of grooves is added to the pressure tube.These grooves allow the piston to move relatively freely in the middle range of travel (i.e., most common street or highway use, referred to by engineers as the "comfort zone"), and with less movement in response to more irregular surfaces,degrees of freedom to move when the piston begins to move up and down with greater intensity (i.e., on rough roads - intensification gives the driver more control over the vehicle's motion, so its range on either side of the comfort zone referred to as the "control" zone").This advancement allows automotive designers to create shock absorbers that fit specific makes and models and take into account a given vehicle's size and weight, maneuverability, horsepower, etc.when producing correspondingly effective shock absorption.

Acceleration sensitive damping

The next stage in the evolution of shock absorbers is the development of a shock absorber that not only senses and responds to changes in conditions from "bump" to "smooth," but responds to individual bumps in the road in a near-instantaneous reaction. reaction.This is achieved by changing the design of the compression valve, known as "acceleration sensitive damping" or "ASD". Not only does this lead to the complete disappearance of the "comfort versus control" trade-off, but it also reduces vehicle pitch during braking and roll during cornering. However, ASD shocks are usually only available as aftermarket changes to the vehicle and are only available from a limited number of manufacturers.

Coilover

A coilover shock is typically a twin tube gas-filled shock inside a coiled road spring.They are commonly found in the rear suspensions of motorcycles and scooters and are widely used in the front and rear suspensions of automobiles.

Single-tube

The main design alternative to the twin-tube form is the single-tube shock absorber, which was considered a revolutionary advancement when it appeared in the 1950s.As the name suggests, a monotube shock absorber is also a gas-pressurized shock absorber, also in the form of a shock absorber, and although it has two pistons,it consists of only one tube (the pressure tube). These pistons are called the working piston and the diverter piston or floating piston, and they move relatively synchronously within the pressure tube in response to changes in road roughness.The two pistons also completely separate the shock's fluid and gas components.The overall design of monotube shock absorbers has always been much longer than twin-tube shock absorbers, so it is difficult to install in passenger cars designed for twin-tube shock absorbers.However, unlike twin tubes, monotube shocks can be mounted arbitrarily it doesn't have any directionality.It also doesn't have a compression valve, the role has been taken over by the splitter piston, although it contains nitrogen, the gas in the monotube shock is at high pressure (around 260-360 p.s.i.) which actually helps it to support the vehicle's Part of the weight, something no other shock absorber can do.

Beginning in 1958, Mercedes was the first automaker to install monotube shock absorbers as standard equipment on some cars.They were manufactured by Bilstein, patented their design, and first appeared in 1954.Since the design was patented, other manufacturers could not use it until the patent expired in 1971.

Spool valve

Unlike traditional conventional flexible discs or gaskets, spool dampers feature the use of a hollow cylindrical sleeve with machined oil passages.Spool valves are available in single-pipe, double-pipe and/or position sensitive packages and are compatible with electronic controls.The key advantage cited in Multimatic's 2010 patent application is the removal of performance ambiguities associated with flexible gaskets, resulting in mathematically predictable, repeatable and robust pressure-flow characteristics.