1、AEROSPACE INFORMATION REPORTAIR560 REV.CIssued 1957-08Revised 1999-12Superseding AIR560BMissile Hydraulic Pumps1. SCOPE:1.1 Missile pumps are categorized by a moderate testing life and a relatively short operational service life. Generally, the pumps are operated at higher speeds, temperatures, and
2、pressures than those used in manned aircraft systems, yet reliability must be extremely high, since there rarely is a redundant system aboard the missile. Due to the short but critical life and performance requirements, development, reliability and acceptance testing should be focussed on eliminatin
3、g infant mortality failures.1.2 Missile pumps must be compatible with very severe environmental conditions during the service life. In general, the temperature, vibration, shock, and acceleration encountered are more severe than those met in manned aircraft.1.3 This SAE Aerospace Information Report
4、(AIR) will be confined to describing missile environments and pump usage that differ significantly from those normally encountered in manned aircraft. Since missile pumps are usually driven by a secondary power source, and since this AIR is intended for use by systems designers, as well as pump desi
5、gners, a brief description of some of these sources and some potential problem areas associated with each are included for reference. A more detailed treatment of auxiliary power sources can be found in AIR744.1.4 Detailed test requirements are not included in this AIR since a wide variation exists
6、between those operating conditions and environments that might be encountered on an air-to-air missile, hung beneath the wing of a fighter aircraft, and that of an ICBM (Intercontinental Ballistic Missile), launched from an environmentally controlled silo. Missile pumps frequently have their genesis
7、 in standard aircraft pumps, however, what distinguishes them from manned aircraft pumps is that they are usually operated outside of, or at the extreme of their long-life design parameters. Therefore, if a new design pump is being proposed for a missile application, environmental conditions referen
8、ced in this AIR should be considered, as opposed to long-life operation and environmental requirements of a manned aircraft, engine-driven pump.Reaffirmed 2007-07RATIONALEThis document has been reaffirmed to comply with the SAE 5-Year Review policy.SAE Technical Standards Board Rules provide that: “
9、This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE re
10、views each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions. Copyright 2007 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or tra
11、nsmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PLACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: CustomerServicesae.org SAE
12、WEB ADDRESS: http:/www.sae.org SAE AIR560 Revision C- 2 -1.4 (Continued):Appendix A is intended to indicate typical environments for several different types of missiles. The actual requirements for a given system should be used and specified in the detailed specification.1.5 Purpose:1.5.1 This AIR d
13、elineates those factors in which the requirements of hydraulic pumps for use in missiles differ from the requirements of hydraulic pumps for use in manned aircraft.1.5.2 It is intended that this AIR shall alert both the pump designer and systems designer to these differences and thus achieve lighter
14、, simpler and more reliable hydraulic pumps which are particularly suited for missile use.2. REFERENCES:2.1 SAE Publications:Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.ARP598 Determination of Particulate Contamination in Liquids by the Particle Count MethodAIR744 Aerospace
15、 Auxiliary Power SourcesAIR974 Long-Term Storage of Missile Hydraulic SystemsAS4059 Aerospace - Cleanliness Classification for Hydraulic FluidsAS5440 Hydraulic Systems, Aircraft, Design and Installation, Specifications ForAS19692 Pump Units, Hydraulic, Variable Delivery, General Specification For2.2
16、 U.S. Government Publications:Available from DODSSP, Subscription Services Desk, Building 4D, 700 Robbins Avenue, Philadelphia, PA 19111-5094.MIL-STD-461E Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and EquipmentsMIL-STD-810 Environmental Test Methods a
17、nd Engineering Guidance3. REQUIREMENTS:3.1 Materials:3.1.1 All materials shall be carefully chosen for chemical and dimensional stability when subjected to extremes of temperature and varieties of hydraulic fluids.3.1.1.1 The choice and installation of elastomeric materials are particularly strongly
18、 affected by ranges of temperature and pressure and the chemical nature of the hydraulic fluid. Careful attention must be paid to the requirements of the detailed specification.SAE AIR560 Revision C- 3 -3.1.1.2 Chemically active materials such as cadmium, zinc, and silver whose reactions with other
19、materials are accelerated by high operating temperatures shall not be used in contact with the operating fluid. In elevated temperature applications (fluid or ambient), consideration should also be given to the stress alloying with steel components. In particular, cadmium shall not be used at temper
20、atures conducive to stress alloying of steel parts.3.2 Design and Construction:3.2.1 All dynamic spring-mass systems in the pumps shall be damped to an extent that assures no adverse operation under the specified vibrational requirements. Insure that acceleration forces will not adversely affect the
21、 compensator control (variable pumps).3.2.2 All compliant members shall be chosen, designed, or installed such that any changes in strength and/or modulus of elasticity caused by changes in the temperature environment will not affect the operating characteristics of the pump.3.2.3 Insofar as possibl
22、e, the pump design shall minimize the effect on performance resulting from changes in fluid viscosity, density, and compressibility caused by changes in temperature.3.2.4 If cooling circulation ports are used, the flow passages in the pump should be designed so that they will not add additional pres
23、sure drop (heat) in the circulation process. In applications where the pump is contained in a reservoir, the reservoir shall be capable of heat radiation. In cases where the reservoir radiation is insufficient, the downstream leakage and/or system bleeds can be considered for heat dissipation.3.2.5
24、The pump drive shaft shall not incorporate a shear section and have at least the capability of withstanding the torque of the internal pump drive mechanism. This precludes premature failure in rapid start-ups, or high pressure surge conditions.3.2.6 It is desired that provisions for the automatic pu
25、rging of gases entrained within the fluid be included in the pump design. This frequently may not be possible, and therefore, care must be exercised in the filling and bleeding procedures used. Where possible, vacuum filling shall be considered.3.2.7 The reduction of weight is of extreme importance.
26、 This shall include consideration of enclosed fluid as well as the weight of the pump structure. Use of “plug-in“ pumps, manifold porting, and nonstandard mounting flanges should be considered.3.2.8 Because of the stringent reliability requirements, a very high quality of workmanship shall be used i
27、n fabricating the pumps. In particular, great care must be exercised to avoid free particles, hanging burrs, or other contaminants that may dislodge during operation and initiate a malfunction within the pump or within the system in which the pump will be used.3.2.9 Where pumps are to be operated at
28、 high temperatures, nameplates, identification tags, inspectors marks, etc. should be of thermally inert materials and attached in a manner that will not be affected by high temperature. For pumps submerged in oil, minimum external marking should be permitted. All marking should be either of a perma
29、nent nature or by nameplates securely attached to the pump body.SAE AIR560 Revision C- 4 -3.2.10 It is desirable that pumps be designed so that the effects of variation in inlet pressure are minimized. System designers should be aware of the effects of variation in inlet pressure on discharge pressu
30、re and design accordingly.3.2.11 The overall efficiency of the pump shall be as high as possible, consistent with the requirements of the missile and cost-effectiveness. The low flow losses may be more important than the full flow losses. Sometimes, trade-offs in these areas are possible, for exampl
31、e, with DC motor driven pumps, it may be possible to improve the partial flow efficiencies at the expense of full flow efficiency by modifying the electric motor characteristics, to minimize the total watt-hour drain.3.2.12 The pump shall not be subjected to testing in which a design misalignment be
32、tween the base of the pump mounting flange and the test mounting fixture exists unless such a possibility also exists in the actual application.3.2.13 Shaft seal leakage, especially during storage, is frequently a problem. Storing pumps in systems with 1 to 5 psig (7 to 35 kPa) inlet pressure requir
33、es careful design in the shaft seal area. Typical allowable leakage is 13 drops (0.05 in3) (818 mm3) per year, static; 1 drop per 5 min, operational. However, some systems specify zero leakage.Provision should be made for visually determining if leakage has occurred and for suitable ways of measurin
34、g any leakage without disassembly of the unit.3.2.14 Rapid start-up of the pump with only low reservoir storage inlet pressure (especially at cold temperature) can cause pump damage and/or inability to meet initial flow/pressure requirements in some systems. Influencing factors are acceleration time
35、, choice of fluid, reservoir type and initial pressure, pump design, and operating speed. Prefiring warm-up time and/or heater blankets are additional considerations in very low temperature start environments.3.2.15 Many hydraulic pumps can operate for one-duty cycle well above the rated temperature
36、. For example, AS5440 Type II pumps 275 F (135 C), can reliably perform one terminal cycle up to 350 to 400 F (177 to 204 C). Temperatures from -65 F (-24 C) to over +700 to 800 F (371 to 427 C) are being considered for missile pumps. Operation at extreme elevated (over design) temperatures must con
37、sider the limited volume of fluid in the system and relate this to limited fluid leakage requirements.3.2.16 Contamination control is a major problem in aircraft hydraulic systems. It is even more critical in missile systems. Pumps should be examined for contamination-generating chracteristics and a
38、lso for the ability to survive in a contaminated environment. In systems where contamination is critical, a patch test, as reflected in AS19692, should be established; the wear-out characteristics and performance degradation of the pump with oil contaminated to the level expected in the missile shou
39、ld be explored. Almost all systems incorporate a filter in the outlet of the pump. Filters usually are between 3 to 10 m, depending on the dirt sensitivity of the system and the contamination level expected. It is good practice to use a “clean-up“ filter during initial system operation, and replace
40、it with a clean unit prior to delivery.SAE AIR560 Revision C- 5 -3.2.17 Indications are that pumps can operate satisfactorily after up to 5 to 15 years or longer in storage, depending on the environment, frequency of exercise, etc. Refer to AIR974 for additional information.3.2.18 Because missiles o
41、perate in small, tight systems, control stability of variable displacement pumps shall be explored in the early stages of system development. Functional test stands for production pumps shall simulate, as nearly as possible, the line sizes and lengths expected in the missile system.3.2.19 The maximu
42、m speed at which a pump can reliably operate is a function of displacement (the lower the displacement, the higher the maximum speed), and to a lesser degree, temperature, and pressure. Speed can also be limited by inlet pressure or ability to load. For the smaller piston pumps, speeds up to 30,000
43、rpm are feasible. Efficiency tends to fall off at the higher speeds, primarily due to windage losses. Centrifugal pumps can be operated at much higher speeds, but efficiencies tend to be low.3.2.20 Missile pumps tend to be used over a much wider range of pressures than an aircraft pump, and because
44、each missile generally has much of its hydraulic equipment especially designed for it, and weight and space are at a premium, rated pressures tend not to be the conventional 1500/3000 psi (10 MPa/21 MPa) but whatever pressure is found to be optimum for a particular system (e.g., 3400 psig/23.4 MPa).
45、3.2.21 Although the pump itself is generally insensitive to the nature of the duty cycle (as long as operating conditions stay within design parameters), this is frequently a critical design problem to the supplier of the power source that drives the pump. This appears to be one of the most difficul
46、t areas to pin down and frequently results in underdesigned or overdesigned power sources with its attendant reliability and/or weight penalties. An early effort to define the duty cycle in realistic terms is well worthwhile.4. DRIVING SOURCES:4.1 A number of auxiliary power sources may be used to d
47、rive the pump. In this AIR, some of the more common power sources that drive missile pumps will be briefly described, and some of their characteristics that interrelate with pump characteristics will be discussed. Refer to AIR744 for a more detailed discussion of some of these power sources.SAE AIR5
48、60 Revision C- 6 -4.1.1 DC Electric Motors (28 and 56 V and Higher): Use of a DC motor for a missile hydraulic pump drive will usually require an aircraft-quality type motor. The design considerations, although quite similar to many aircraft applications, are generally more restrictive. Weight, size
49、, and available power are especially critical, and dynamic environmental requirements such as acceleration, shock, and vibration may be more severe. Although end usage may only be a one-shot duty cycle of only a few minutes duration, the operational life requirements will usually specify many repeated cycles that may accumulate a total life of 50 h or up to 100 times operating life. Since the energy stored in the battery becomes the limiting factor for the total mission, the b
