Product category:
Electric Linear Actuators
News Release from: SMAC Europe | Subject: LAL300 and LAL500
Edited by the Engineeringtalk Editorial
Team on 08 February 2008
Actuators stand the test of cleaner
combustion
The use of moving coil actuators improves the accuracy of spring characterisation in the manufacture of diesel injectors.
SMAC moving coil actuators are helping a world-leading manufacturer of diesel injectors to reduce emissions by using an actuator to determine the spring characteristics in its injectors The standard SMAC characteristics of programmable force control coupled to submicron resolution encoder feedback ensures that the measurement of spring rates and deflection are carried out with great accuracy and repeatability
This article was originally published on Engineeringtalk on 2 Oct 2008 at 8.00am (UK)
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An essential characteristic in any diesel injector is achieving a constant spring rate in the valve head of the injector.
This accuracy of this spring rate has a direct effect on emissions which is crucial in today's climate.
This is achieved by applying a constant load on the spring and measuring deflection.
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Once the deflection is determined a compensating shim is added to achieve the correct performance.
The tolerances on the setting of the spring rates are becoming tighter due to better vehicle performance and emissions regulations.
The traditional method of achieving this was to use a servomotor, ballscrew, load cell and LVDT.
Predictably this led to a significant stack up of errors and a single device capable of force and position feedback was essential to meet the latest specifications.
SMAC supplied LAL300 and LAL500 systems to specialist machine builder SPE.
The operation cycle of the measuring system is as follows.
First, measure the free position of the uncompressed spring.
Then, apply constant programmable load between 65 and 230N depending on the product.
Thirdly, measure the linear position differential between compressed and uncompressed heights.
And finally, output the differential to the PLC.
The data reported are used to specify the correct-sized shim which is then fitted to the spring and valve assembly to guarantee correct spring rate.
The implementation of the SMAC actuators has led to an immediate and significant increase in quality and reduction in rejects.
According to Chris Baker, Technical Director of SPE: "By using the LAL units and mounting a high accuracy load cell directly in line we have been able to reduce measuring variation from approximately 6um to below 2um".
"This means that the customer is setting valves for the injectors within a much tighter tolerance".
"This has a subsequent affect that the first time pass rate on final function test for the new generation of injectors has improved massively from typically below 75% to over 95%". Request a free brochure from SMAC Europe ...
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