Measuring and testing – Blower – pump – and hydraulic equipment
Patent
1996-07-10
1997-12-09
Raevis, Robert
Measuring and testing
Blower, pump, and hydraulic equipment
G01M 1900
Patent
active
056948085
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of testing the function of a hydraulic device, more particularly, a device for converting mechanical into hydraulic energy, for example, a pump for incompressible media, according to the preamble of claim 1.
BACKGROUND OF THE INVENTION
In prior art methods of testing the function of hydraulic pumps, the function of the pumps is tested under operating conditions. To this end, the hydraulic medium is supplied from the pump, and the medium flow rate and the pump outlet pressure are checked. If the values are within the nominal tolerance range, the pump is considered operable.
A disadvantage of this so-called wet testing is that fluid is in the pump and must be removed before the pump is delivered from the manufacturer to the user. Cleaning the pump necessitates intricate work, and it is impossible to remove the hydraulic medium 100 percent without considerable effort. This effort is compounded when the pump is intended for use in a hydraulic brake system for automotive vehicles, such as an ABS/TCS system, because those systems are typically filled using vacuum techniques. When using vacuum techniques, the pump must not contain remnant fluid because otherwise vacuum filling of the brake system would be extremely time consuming. This is because the entire fluid which is still in the pump would have to be pumped off initially to provide a vacuum. This requirement involves excessive time even for small amounts of fluid.
U.S. Pat. No. 4,598,579 discloses a method of testing the function of an individual hydraulic component part for incompressible media by way of a compressible medium. A disadvantage in the prior art arrangement is that, for reducing disturbances caused by the components of the measuring system, the design of the measuring system must be conformed especially to the testing of the above individual component part by using a compressible medium.
Therefore, an object of the present invention is to propose a method of testing the function of hydraulic devices, permitting the delivery of virtually dry devices, in particular pumps, and eliminating the above-mentioned drawbacks.
Another object of the present invention is to provide a function testing method which is as inexpensive as possible and, in addition, permits tracing possible production defects.
Accordingly, the invention proposes testing a completely assembled device including a plurality of individual hydraulic components and using a compressible medium for testing instead of the incompressible hydraulic medium, i.e., the given operating medium of the device. The device may be a pump, a motor or a turbine, etc. In the simplest case, air will be used, for example, oil-free compressed air, but the use of gases such as nitrogen, helium, or even steam is also possible.
The method of testing the function of hydraulic devices according to the present invention is based on the idea that a no-load operation test of the device is sufficient to check the tightness and proper interaction of all structural elements of the device. That means, structural elements which do not function in the virtual operation will be detected during the function test by way of the compressible medium.
The pressure is measured at the pressure fluid inlets and outlets of the device during the function test. Such measuring operations can be performed by low-cost and easy-to-install pressure sensors. A complicated determination of the supply rate is not necessary.
In this arrangement, it is appropriate that the power operating the device to be tested is conformed to the properties of the compressible medium, meaning the drive power with respect to a pump and the output for a motor. To ensure a reproducible function test, the power can be chosen to be superior or inferior to the given nominal capacity. This will eliminate resonant vibrations of the compressible medium or other undesirable effects.
A determined starting pressure is initially applied to the device to be tested. On the one hand, this serves to provide a de
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Search Report of the German Patent Office for Application No. P4337521.9.
ITT Automotive Europe GmbH
Lewis J. Gordon
Raevis Robert
Twomey Thomas N.
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