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1、 Reference number ISO 22072:2005(E) ISO 2005 INTERNATIONAL STANDARD ISO 22072 First edition 2005-06-01 Aerospace Electrohydrostatic actuator (EHA) Characteristics to be defined in procurement specifications Aronautique et espace Actionneurs lectrohydrostatiques (EHA) Caractristiques dfinir dans les
2、spcifications dapprovisionnement ISO 22072:2005(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer
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5、tral Secretariat at the address given below. ISO 2005 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO
6、at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2005 All rights reserved ISO 22072:2005(E) ISO 2005 Al
7、l rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a
8、 subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commissio
9、n (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical co
10、mmittees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall no
11、t be held responsible for identifying any or all such patent rights. ISO 22072 was prepared by Technical Committee ISO/TC 20, Aircraft and space vehicles, Subcommittee SC 10, Aerospace fluid systems and components. INTERNATIONAL STANDARD ISO 22072:2005(E) ISO 2005 All rights reserved 1 Aerospace Ele
12、ctrohydrostatic actuator (EHA) Characteristics to be defined in procurement specifications 1 Scope This International Standard defines the general characteristics, requirements and design data to be included in the procurement technical specification of an electrohydrostatic actuator (EHA) to be use
13、d to power aircraft control surfaces or other moving parts of an aerospace vehicle. This type of actuator is an alternative to the hydraulically powered servocontrol actuators that are currently used. It is intended that this International Standard cover the unique requirements of EHAs. Test methods
14、 are defined in a separate ISO document. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendm
15、ents) applies. ISO 7137, Aircraft Environmental conditions and test procedures for airborne equipment 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 electrohydrostatic actuator EHA electrically powered actuator that includes one or several h
16、ydraulic rams whose chambers are connected to a bi-directional, fixed-displacement pump driven by a variable-shaft-speed, electric motor controlled by power electronics NOTE 1 A typical arrangement includes an integrated hydraulic fluid compensator, a manifold that interconnects the above hydraulic
17、elements and in which components necessary for additional functions can be installed, see Figure 1. NOTE 2 This assembly is part of the position control loop of the surface, or of any other load, in which the error signal, difference between the commanded and achieved positions, determines the comma
18、nd of the speed and direction of rotation of the motor. Other components of the position servo loop, e.g. position transducer, control electronics generating the error signal and control laws, do not necessarily form part of this assembly. NOTE 3 This assembly may also perform other functions, for e
19、xample allowing the operation of other actuators installed in parallel, or ensuring the damping of movement of the load in case of loss of all electric power. ISO 22072:2005(E) 2 ISO 2005 All rights reserved Key 1 command signal 2 power supply 3 power electronics 4 electric motor 5 fluid compensator
20、 6 pump 7 position transducer signal 8 check valve (2 places) Figure 1 Typical arrangement of an electrohydrostatic actuator 4 Requirements 4.1 General The requirements defined in 4.2 to 4.13 shall be met under all rated operating conditions and during the service life specified. 4.2 Brief descripti
21、on of the system The EHA is one component of a system. The various configurations or reconfigurations typical of this system involve specific modes of EHA operation which shall be described. Normal and failure modes of operation for the EHA shall be defined. 4.3 Description and interfaces 4.3.1 Gene
22、ral description The unit shall be described in terms of functions and the associated terminology defined. The following are examples: control/electrical/mechanical/structural redundancy, local or remote fluid level indication, ISO 22072:2005(E) ISO 2005 All rights reserved 3 filling, draining, bleed
23、ing, internal fluid filtering, no-back, local dissipation of generated energy, force or speed limitation, stops, temperature monitoring, heating of stand-by unit. 4.3.2 Mechanical interface The specification drawing shall define the following: allocated space envelope; dimensions and tolerances of t
24、he mechanical connections or the dimensional standards if connections are achieved through standardized components; line replaceable units (LRUs); access once installed on aircraft; specific items such as hoisting or jack catcher interfaces, as required. 4.3.3 Electrical interface The electrical int
25、erface definition shall include wiring schematics defining the electrical connections with power supply, control and monitoring systems, standards, sizes and pin allocation of interface connectors; any particular requirements or limitation on use of connectors for the LRUs; segregation rules to comp
26、ly with; descriptions of signals exchanged, definition of input and output impedances; power interruption capability and definition of the strategy for longer interruptions (see 5.3). 4.3.4 Hydraulic interface The hydraulic interface requirements shall include definition and location of possible fil
27、ling, bleeding, filtering and draining features. ISO 22072:2005(E) 4 ISO 2005 All rights reserved 4.3.5 Software Software may be used to achieve various functions, such as electric motor control, loop closure, monitoring and redundancy management, status information, built-in test. The level of crit
28、icality and of the associated development, verification, and validation methods shall be specified. Memory capacity extension and processing power shall be specified. If required, dissimilarity in processing/software/compilers/electronic hardware shall be specified. 4.4 Performance 4.4.1 Mechanical
29、performance The definition of the requirements for output force or mechanical power shall take into account the thermal behaviour. These mechanical requirements shall therefore be associated with their duration and environmental conditions. Thus the following shall be specified. Maximum operating ou
30、tput force: the maximum driving force to be generated by the unit at very low speed (to be defined), for a short time duration (to be defined), under specified supply and environmental conditions, and the associated tolerances. Maximum continuous output force: the maximum holding force, with no move
31、ment, or the maximum driving force, at very low speed (to be defined), to be generated under given supply and environmental conditions with no time limitation, with and without its possible no-back device engaged, and the associated tolerances. Worst case scenarios: operational sequences, or series
32、of sequences, described as functions of time in terms of position, force, environmental conditions, identified as sizing cases in terms of the instantaneous power absorbed or rejected, or in terms of heat generated. Force fighting shall be considered, depending on system configuration. Maximum rate
33、and associated loading conditions, or expressed as the time necessary to reach a given position under a specified load. The rate versus load characteristic shall be identified. Run-up time: time from activation of stand-by actuator to being able to achieve maximum rate with a maximum rate demand. Dy
34、namic performance as specified below may also be a sizing consideration. Working stroke, stop to stop stroke. Possible acceptable temporary degradation of performance at start up, following cold soak in particular. ISO 22072:2005(E) ISO 2005 All rights reserved 5 4.4.2 Servo loop static performance
35、The following characteristics, with and without the possible no-back device, shall be specified: overall accuracy, hysteresis, resolution, stiffness, freeplay. 4.4.3 Servo loop dynamic performance and stability Bandwidth of the position servo loop shall be expressed in terms of amplitude ratio and p
36、hase lag in the frequency range, for defined amplitudes and loads. The following shall be specified: maximum acceptable overshoot; minimum acceptable stability margins of the position servo loop and any minor control loops (e.g. motor speed); acceptable speed oscillation, characterized by frequency
37、and amplitude (motor and pump may generate torque ripple); response time of the possible no-back device; acceptable limit cycle (a no-back device may generate a limit cycle); dynamic performance and stability of the servo loop, the input being the force applied to the actuator, the output being the
38、piston position, at constant command. 4.5 Electrical power consumption Steady state power consumption with no movement, as a function of the applied load, and peak consumption in the course of typical manuvres, under specified supply conditions, shall be specified. 4.6 Hydraulic consumption Allowabl
39、e fluid loss, allowable refill interval, and life of fluid shall be specified. 4.7 Strength and life 4.7.1 Static strength Static strength is defined by the following. Limit load (without permanent deformation or leakage): maximum specified driving or resisting force, with or without movement, gener
40、ated by the unit with account taken of any force limitation function possibly incorporated. In the case where a no-back device is included, the maximum holding force may define this limit load. Ultimate load (without rupture): 1,5 limit load. ISO 22072:2005(E) 6 ISO 2005 All rights reserved Proof pr
41、essure (without permanent deformation or leakage): 1,5 maximum permanent pressure associated with the limit load. For lines only submitted to the fluid compensator pressure: 1,5 maximum fluid compensator pressure. Ultimate pressure (without rupture): 2 maximum permanent pressure associated with the
42、limit load. For lines only submitted to the fluid compensator pressure: 2 maximum fluid compensator pressure. Other sizing cases, not specific to EHA and depending on the system configuration, may apply. If the actuator is connected to a hydraulic system, in order to avoid the need to service, for e
43、xample, the usual hydraulic system sizing conditions shall apply to all parts exposed to the system pressures. Stops must be able to withstand any loads corresponding to the design conditions of the control system. 4.7.2 Fatigue and wear life The fatigue life under external loads and pressure transi
44、ents possibly generated by the operation of the unit is associated with the absence of crack initiation. In general, the fatigue life of the actuator is equivalent to the structural life of the vehicle. Appropriate scatter factors shall be used. If the actuator is connected to a hydraulic system, th
45、e usual hydraulic system pressure impulse requirements shall apply to all parts exposed to the system pressures. As regards wear life, performance shall remain within the limits specified. All components do not necessarily have the same life objective. 4.8 Protection against fire risk Special precau
46、tions against fire risk shall be specified: protection and monitoring functions, physical separation, precautions against electric arcs, maximum acceptable temperatures, fluid contact with hot parts, dispersal of possible leakage. 4.9 Reliability and safety Criticality level shall be defined. Reliab
47、ility shall be specified according to the application (mean time between failures, MTBF). Safety shall be expressed in terms of probability of loss of function, runaway, etc. Possible specific EHA failure modes shall be addressed (e.g. motor/pump possible overspeed when back-driven by the load). 4.1
48、0 Bonding Maximum resistance between any point of the EHA and the bonding connection shall be specified. ISO 22072:2005(E) ISO 2005 All rights reserved 7 4.11 Lightning, electromagnetic compatibility Levels shall be specified according to ISO 7137. 4.12 Maintainability and servicing Maintainability
49、requirements shall include, where applicable, markings; handling devices for heavy equipment; checking the fluid level; fluid contamination control; fluid level settings, bleeding, drainage, and renewing, on aircraft or in the workshop; definition of line replaceable units (LRUs); tests based on the observation of such parameters as speed or current; built-in fault detection an