In modern vehicles, an automobile liquid accumulator plays a crucial role in the efficient functioning of various liquid-based systems like the engine cooling system, power steering system, brake system and air conditioning system. As vehicle technologies become more complex with the integration of advanced electronics and increased precision requirements, having a robust liquid accumulator has become even more important. This article aims to explain the working, need and types of liquid accumulators used in automobiles.
Working of an Automobile Liquid Accumulator
A liquid accumulator is essentially a vessel that stores pressurized liquid to balance pressure fluctuations in hydraulic or cooling systems of a vehicle. It maintains optimum system pressure even when the engine or pump is idle by acting as a reserve. During demand spikes when additional liquid is needed rapidly, the accumulator provides extra flow by releasing stored pressurized fluid. This prevents pressure drops that can cause system failure or performance issues.
Most Automotive Accumulators have a sealed gas chamber separated from the liquid chamber by a flexible diaphragm or piston. The compressible gas, usually nitrogen, maintains a pre-charge pressure on the liquid side. As demand increases, the gas compresses to push more liquid into the system. During lulls, the gas expands to draw liquid back into storage. This absorption and release of pressure pulsations ensures smooth system functioning.
Need for an Automobile Liquid Accumulator
Vehicle hydraulic and cooling systems need to continually supply regulated fluid flow even as operating conditions vary. However, mechanical pumps alone cannot instantly meet every demand spike or perfectly cushion every pressure surge. This is where an accumulator plays a crucial damping role:
– It stabilizes system pressure during pressure transients caused due to starting/stopping of the engine or pumps. Without an accumulator, these fluctuations can cause major issues.
– Accumulators provide extra instantaneous flow on demand to avoid pressure drops. For example, sudden opening of multiple valves or engaging of accessories requires burst flow beyond a pump’s capacity.
– They cushion pressure ripples and water hammer effects in long fluid lines that can damage components otherwise. Accumulators smooth pressure waves.
– The reserve volume of pressurized fluid maintained ensures uninterrupted system function, preventing failures if pumps stall momentarily.
– Accumulators help minimize pulsing discharge from positive-displacement pumps for quieter operation free of pressure surges.
Types of Automotive Liquid Accumulators
There are a few standard accumulator designs used in vehicles depending on the application requirements:
Bladder Type
A rubber bladder separates the gas and liquid chambers. It flexes in and out with pressure changes to pump liquid into the system. Economical and common type used for engine cooling, air conditioning etc.
Piston Type
A sliding piston takes the place of the bladder. Offers higher pressure ratings than bladder types. Often used in high-pressure hydraulic systems like power steering or rear wheel drive differentials.
Diaphragm Type
Similar to bladder type but uses a corrosion-resistant flexible diaphragm instead of rubber. Sealed units suitable for long-term use with chemically aggressive brake fluids and transmission fluids.
Spiral Winding Type
A coil spring replaces the gas pre-charge in this design. Provides extra storage but more complex than gas pre-charge types. Mainly used where regular gas charging is not feasible.
Selection Factors for Automotive Liquid Accumulators
Key factors determining the ideal accumulator type and size for a vehicle application include:
– Operating pressure and pressure ripple magnitude
– Fluid temperature and chemical compatibility
– Space envelope and weight constraints
– Required standby volume and surge flow capacity
– Life cycle and maintenance requirements
– Compliance with industry quality and safety standards
– Cost implications
Automakers collaborate closely with accumulator manufacturers at design stage to specify the right products matching the application. System simulation also helps finalize accumulator parameters.
As modern vehicles rely more on hydraulics, thermodynamics and precise mechatronics for efficient driving and passenger comfort, liquid accumulators have become indispensable components safeguarding sensitive systems prone to pressure fluctuations. Their hassle-free damping action performed quietly keeps vital flows regulated for safe, long-term vehicle operations. Further accumulator innovations will continue enhancing automotive engineering.
