WO1988008524A1

WO1988008524A1 - Automatic test equipment for hydraulic devices

Info

Publication number: WO1988008524A1
Application number: PCT/US1988/000951
Authority: WO
Inventors: Melvin Schecker; Robert J. Williams
Original assignee: Grumman Aerospace Corporation
Priority date: 1987-04-24
Filing date: 1988-03-28
Publication date: 1988-11-03
Also published as: IL86036A0

Abstract

A variety of hydraulic units (10) may be tested by a single apparatus. A microprocessor (18) furnishes a pump (24) with control signals for pressurizing hydraulic fluid and varying the flow output to preselected levels. A fluid control test panel (12) includes a valve (52) for directing pressurized fluid into the inlet and then into the outlet of a unit undergoing test to complete leakage tests. Transducers (58) sense mechanical motion parameters as parts of the unit undergoing test are moved by controlled amounts. Electrical outputs from the transducers drive measurement instruments (60) and resulting measurements are stored in the microprocessor (18).

Description

AUTOMATIC TEST EQUIPMENT FOR HYDRAULIC DEVICES

FIELD OF THE INVENTION The present invention is related to automatic test equipment (ATE) , and more particularly to such automated equipment for testing hydraulic devices.

BACKGROUND OF THE INVENTION There is an increasing need and desire for automatically testing the performance capabilities and reliability of hydraulic devices. This is particularly true in equipment for the armed services. For example, military aircraft include a host of hydraulic devices which must be periodically checked for performance and leakage.

In the ^"past, this has generally been accomplished in two ways. The first way was the manual testing of hydraulic devices which is a very time-consuming operation due to the wide variety of devices with which personnel must acquaint themselves. A second way of testing hydraulic devices involved the utilization of different specialized test equipment for each particular device. As will be appreciated, this is a prohibitively expensive and impractical solution, particularly in a military environment.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention is directed to automatic test equipment for hydraulic devices that lends a degree of universality to a wide variety of hydraulic devices.

By relying upon a microprocessor program to vary the parameters of fluids delivered to a hydraulic device undergoing test, accurate and repeatable testing results may be obtained without relying upon extremely knowledgeable technicians. Further, by relying upon the adaptability of a microprocessor-based program, a single test equipment can be generally employed for various types of hydraulic devices which must undergo test. Accordingly, the present invention achieves accurate and precise testing results with great cost efficiency inasmuch as a single test set-up may be employed for a multitude of different hydraulic devices requiring test. By virtue of the automated procedure which the present invention offers, technicians of average ability may be employed.

BRIEF DESCRIPTION OF THE FIGURES The above-mentioned objects and advantages of the present invention will be more clearly understood when considered in conjunction with the accompanying drawings, in which:

FIG. 1 is a basic block diagram of the present invention; FIG. 2 is a basic block diagram of a hydraulic power unit as employed in the present invention;

FIG. 3 is a block diagram of a test panel as employed in the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring to the figures, and more particularly FIG. 1 thereof, a basic block diagram of the present invention is illustrated. A hydraulic device to undergo test is indicated by reference numeral 10 in FIG. 1. In order to provide the hydraulic device with predetermined fluid flow parameters, a fluid control test panel 12 is connected to the unit under test 10 by means of supply and return lines 15. Pressurized and cooled fluid is provided to the test panel 12 by hydraulic power unit 14, the panel 12 and power unit 14 being interconnected by supply and return lines 16. A microprocessor 18 provides control signals along line 20 to the hydraulic power unit 14 so that a pump within the power unit can produce predetermined flow and pressures for the test panel 12. The microprocessor 18 also includes a bidirectional connection line 22 with the test panel 12 so that predetermined electrical control signals can be provided to the test panel 12, which in turn will drive a hydraulic unit undergoing test. Transducers are included within the test panel 12 so that physical measurements including displacement, velocity, force, etc., may be made of the hydraulic device parts while it undergoes testing. The program for the microprocessor 18 includes the necessary signals for producing fluid and electrical parameters in accordance with the various hydraulic devices that will be tested. Once given the specifications for a particular hydraulic device, it is straightforward to write a particular program but the program is not part of the present invention, per se. FIG. 2 is a block diagram of the hydraulic power unit 14. As will be seen, the heart of the hydraulic power unit is pump 24, which generates a desired pressure in accordance with a corresponding command along electrical line 30 coming from the microprocessor 18. A reservoir 26 normally stores hydraulic fluid and supplies it to pump 24 along hydraulic line 28. The pressurized fluid 32 is filtered at filter 34 and is provided to the test panel from outlet port 36. A return fluid path to the power unit 14 is provided at inlet port 38. A cooler 40 is provided downstream from the inlet port 38 to cool the returned hydraulic fluid; and thereafter, the hydraulic fluid is passed along line 42 to a filter 44, where particulate matter may be removed before re-introduction along line 46 to reservoir 26. Conventional pressure regulators 47 are connected between the high and low pressure lines of the power unit so as to prevent the pump 24 from supplying an excessively high pressurized hydraulic fluid to the test panel 12.

The test panel 12 is indicated in greater detail in FIG. 3. A selectively connected unit undergoing test 10 is connected via supply line 54 to solenoid valves 52. The valves 52 control the high pressure and fluid flow provided the test panel along inlet line 48. A flow meter 50 monitors the supply fluid. The unit undergoing test returns the hydraulic fluid to the solenoid valves 52 along return line 56.

In a typical test operation, the unit undergoing test 10 may be an aircraft control surface servo actuator. When testing such a hydraulic device, the

.movable parts are first locked into place and the pressure of the supply hydraulic fluid is varied for preset periods of time, after which visual inspections are made for leakage. A low pressure motor valve 64 may be provided between the high and low pressure lines in the test panel so that variably adjustable low pressure fluid may be - provided to the solenoid valves 52, which in turn provide the low pressure fluid to a unit undergoing test. This would allow the device to be tested for leakage under low pressure conditions. Transducers 58 include pressure readout devices to indicate the correlation between inlet and outlet pressures for the device. Also, once the device is mechanically unlocked, measurements may be made of displacement, velocity and force parameters by the transducers 58. The analog transducer outputs are provided to appropriate electronic instruments 60, which generate digital measurement signals along output line 62 to the microprocessor. The measurements and response to microprocessor-controlled fluid parameters at the unit undergoing test determine whether the unit successfully completes its test. The test panel 12 includes a flow cycling or reversing valve means 68 of conventional design to reverse the flow between inlet and outlet ports of the test panel when simple hydraulic devices, such as a cylinder, are to be so tested. Further, a relief valve or bypass 66 is connected between the high and low pressure ports so as to prevent the development of excessively high damaging pressures in the test panel 12. When hydraulic devices which are electrically controlled are to be tested, the microprocessor generates appropriate electrical commands, along line 70, which are converted by a conventional signal generator 72 to appropriate analog voltages. These voltages are input to the unit undergoing test 10 along line 74.

By virtue of the previous description, it will be appreciated that the present invention makes it possible to test a number of different types of hydraulic units with a single test set-up which will furnish accurate and reliable measurements.

^"It should be understood that the invention is not limited to the exact details of construction shown and described herein, for obvious modifications will occur to persons skilled in the art.

Claims

1. A programmable testing apparatus for different types of hydraulic units (10) , the apparatus comprising: a microprocessor (18) for generating command signals for a particular hydraulic unit undergoing testing; hydraulic power means (14) having an electrical control input (14) connected to the microprocessor for providing a fluid under pressure, as dictated by the microprocessor; first valve means (52) connected between the hydraulic power means and the unit undergoing testing for selectively delivering the pressurized fluid to an inlet port of the unit undergoing testing for testing the seals of the unit undergoing testing; transducer means (58) connected to movable parts of the unit undergoing testing for sensing mechanical parameters thereof in response to the pressurized fluid; analog/digital instrument means (60) for measuring analog outputs from the transducer means (58) and translating them to digital values; and means (62) for connecting outputs from the instrument means to an input of the microprocessor for storing the measured outputs.

2. The structure set forth in claim 1 wherein the hydraulic power means comprises: a fluid reservoir (26) ; and a pump (24) having a) an electrical control input (30) connected to the microprocessor, b) an inlet (28) connected to the reservoir, and c) an outlet (32) for providing the pressurized fluid to the first valve means (52) .

3 . The structure set forth in claim 1 together with second valve means (64) connected across inlet and outlet ports of the hydraul ic power unit for providing a relatively low pressurized fluid to the unit undergoing te st ing thereby testing the l ow pressure leakage performance thereof .

4 . The structure set forth in claim 1 together with means (68) connected across inlet and outlet ports of the hydraulic power unit for providing a cyclically variable pressurized fluid to the unit undergoing testing.

5. The structure set forth in claim 1 together with third valve means (66) connected across inlet and outlet ports of the hydraulic power unit for automatically bypassing the first valve means when the fluid exceeds a preselected pressure thereby preventing damage to the unit undergoing testing (10) '.

6. The structure set forth in claim 2 together with second- valve means (64) connected across inlet and outlet ports of the hydraul ic power unit for providing a relatively, low pressurized fluid to the unit undergoing te st ing thereby testing the l ow pressure l eakage performance thereof.

7. The structure set forth in claim 6 together with means (68) connected across inlet and outlet ports of the hydraulic power unit for providing a cyclically variable pressurized fluid to the unit undergoing testing.

8 . The structure set forth in claim 7 together with third valve means (66) connected across inlet and outlet ports of the hydraulic power unit for automatically bypassing the first valve means when the fluid exceeds a preselected pressure thereby preventing damage to the unit undergoing testing (10) .