1、_SAE Technical Standards Board Rules provide that: “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 theref
2、rom, is the sole responsibility of the user.” SAE reviews 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 2009 SAE International All rights reserved. No part of this publication ma
3、y be reproduced, stored in a retrieval system or transmitted, 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)
4、Fax: 724-776-0790 Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.orgSURFACEVEHICLERECOMMENDEDPRACTICEJ2786 OCT2009 Issued 2009-10Automotive Brake Noise and Vibration Standard Nomenclature RATIONALENot applicable. FOREWORDOver the years a variety of terms have come into use to describe
5、a particular vehicle brake noise or vibration event. Some of these have come to be accepted as definitions. Sometimes a certain type of noise has picked up several different definitions that cause confusion amongst engineers. Other engineers, when hearing a noise or sensing a brake vibration that is
6、 new to them, often struggle to adequately explain it to other persons for lack of terminology. This becomes even more critical in global communications within the engineering community. This document is directed towards standardizing terminology. 1. SCOPE This document defines various vehicular noi
7、ses and vibrations that are attributed to being created by the foundation brake components of the vehicle, particularly on passenger cars and light trucks. These definitions cover both disc and drum brakes. The frequency ranges from near zero Hz (tactile sensations) all the way up to 17 kHz, or the
8、upper limit of normal hearing. These noises and vibrations may either directly radiate off the brake system or provide the excitation energy that causes other vehicle components to react. 1.1 Purpose Establish standard terminology and definitions that can be used to classify or more adequately defin
9、e a particular vehicular noise or vibration event that is caused by the vehicle foundation brake system. 2. REFERENCES There are no referenced publications specified herein. 3. BRAKE SQUEAL The general definition for brake squeal is an audible noise radiating from the brake system components. The br
10、ake squeal heard coming from a given brake corner of the vehicle normally is a fixed frequency or single pure tone; however in some instances, it may contain higher order harmonics of this frequency. The brake squeal frequency typically ranges from 900 Hz to 17 kHz. Under variations in brake stoppin
11、g parameters (such as temperature, pressure, speed, deceleration), the frequency of the brake squeal can jump to a different frequency. According to theory, the specific allowable squeal frequencies are controlled by the resonant modes of the brake components. Brake squeals can exhibit a wide range
12、of variation in time duration or where the noise occurs during the stop. The following definitions can help to further describe particular types of squeals in terms of their frequency content and when the noise occurs during the stop. Copyright SAE International Provided by IHS under license with SA
13、ENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2786 Issued OCT2009 Page 2 of 43.1 Low Frequency Squeal Low frequency squeal refers to brake squeal whose frequency is usually within the 900 Hz to 4 kHz range. 3.2 High Frequency Squeal High frequency squeal re
14、fers to brake squeal whose frequency is usually within the 4 kHz to 17 kHz range. 3.3 Chirp Brake squeal that occurs in short once per rotor/drum revolution bursts during a stop with brake pressure applied. It usually will only occur at low brake apply pressure. 3.4 Off-Brake Chirp This is a short o
15、nce per revolution squeal with the vehicle moving and no brake pressure applied. 3.5 Sustained Squeal When the brake squeal is heard during the entire stop or a major portion of the stop with brake pressure applied. It is defined as a sustained squeal. 3.6 Tip-In Squeal Refers to the brake squeal he
16、ard just at the beginning of the stop when brake pressure is ramping up from 0 to full pressure and the pads/linings are being driven into contact with the rotor/drum surface and abutments. 3.7 Pinch-Out Squeal Refers to the brake squeal heard just at the end of the stop, usually for the last 1/3 to
17、 1/2 of a revolution, and where the brake pressure has not yet been released. 4. HOWL Howl is a very low frequency brake squeal that is associated only with a drum brake. A single fixed frequency noise (may contain harmonics on some occasions) is produced during a stop that typically will range from
18、 above 700 Hz to below 1000 Hz.5. SCREECH (a.k.a. WIRE BRUSH) Brake noise containing two or more frequencies, usually including several high frequency components. During the brake stop there is a rapid and erratic oscillation between these high frequency tones. Human perception fails to distinguish
19、the individual frequencies and senses it as an irritating sound; listeners usually struggle defining what they heard. 6. CONTACT HISS AND GRIND Noise heard during a stop having no distinct frequency component; it is more like a white noise but with frequencies more concentrated in the 100 to 3000 Hz
20、 range.6.1 Contact Hiss A low level hissing or scouring like sound, often noticed more during the break-in of new brakes. 6.2 Contact Grind An abrasive grating or grinding like sound, and more associated with brakes after burnish/bedding. Copyright SAE International Provided by IHS under license wit
21、h SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2786 Issued OCT2009 Page 3 of 47. BRAKE MOAN Brake moan is similar to brake squeal in that it normally has a strong fixed frequency tone; however, the fixed frequency noise is typically in the 200 to 500 Hz
22、range. The very low frequency nature of moan can lead to the noise being radiated off more components than just the brake itself. It is believed that vibration interactions between the brake, suspension, and axle components cause the moan noise. The moan is usually more easily generated with the veh
23、icle moving at speeds below 7 km/h and with light brake apply pressure. 8. GROAN Noise generated inside the vehicle passenger compartment from vibrations induced into compartment panels; the excitation energy comes from the brake, and travels through the suspension and frame and then into the compar
24、tment panels. The noise is sensed as being broad band with frequencies below 400 Hz.8.1 Dynamic Groan The groan heard during a dynamic stop; it usually is more pronounced during a moderate to a higher deceleration and when slowing through the 30 to 10 km/h range. A certain preconditioning stop seque
25、nce is usually required to create the noise. For instance, it may require doing stops to heat the brake above a certain temperature and then waiting for the brake to cool down a bit before getting the groan to happen. The conditioning sequence can vary significantly from one vehicle setup to another
26、. Sometimes the groan spectrum will contain a component that decreases in frequency with vehicle speed (and appears related to a high order of wheel speed, such as number of vanes/channels in the rotor).8.2 Creep Groan This groan happens on vehicles equipped with automatic transmissions. When the ve
27、hicle is stopped and the brake pressure is reduced to a very low level, the idle torque from the transmission will begin to move the vehicle forward. By maintaining the pressure in a very tight band (typically near 3 bar) such that the vehicle rolling speed is in the range of 0.1to 0.5 rpm, then sli
28、p-stick events between the friction material and disk create the groan.8.3 End of Stop Groan (a.k.a. Crunch) Refers to the groan noise heard at the very end of the stop, i.e. the last 1/3 of wheel revolution, and with the brake pressure still applied.8.4 Release Groan (a.k.a. Grunt) The noise heard
29、after the vehicle has stopped and when the brake pressure is released. It is believed to be caused by the release of the windup of the suspension. 9. ROUGHNESS (a.k.a. JUDDER) Vehicle vibrations created by the brake system during a stop that are felt by the driver and passenger; the vibration freque
30、ncy can range between 0 and 60 Hz. The vibrations are primarily felt in the steering wheel, brake pedal, seat, dash, and floor boards. Brake torque variation is the primary contributor to roughness. The frequency of the roughness normally changes with speed and may contain up to eight orders. The mo
31、st prominent are normally the first two orders; these are associated with rotor thickness variation. Suspension and steering components often have a resonant frequency in the 10 to 20 Hz range; when the vehicle slows through these ranges the felt roughness is accentuated. Certain driving parameters
32、often will precondition brake interface parameters that can then aggravate roughness. The following terms are often used to further define roughness and may be combined. For instance high speed hot judder (roughness) can be used to define the roughness that arises from rotor hot spotting that can oc
33、cur under these driving conditions.9.1 Hot Roughness Refers to roughness created when brake temperatures exceed 250 C. Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-SAE J2786 Issued OCT2009 Page 4
34、of 49.2 Cold Roughness Refers to the roughness created when brake temperatures are below 100 C. 9.3 High Speed Roughness Refers to roughness created when braking from speeds greater than 160 km/h. 9.4 Low Speed Roughness Refers to roughness created when stopping from initial speeds lower than 60 km/
35、h. 9.5 Green Roughness Refers to roughness experienced on new vehicles while brake components are being burnished (bedded in), usually during the first 300 km. 10. NOTES 10.1 Marginal Indicia A change bar (I) located in the left margin is for the convenience of the user in locating areas where techn
36、ical revisions, not editorial changes, have been made to the previous issue of this document. An (R) symbol to the left of the document title indicates a complete revision of the document, including technical revisions. Change bars and (R) are not used in original publications, or in documents that contain editorial changes only. PREPARED BY SAE BRAKE NVH STANDARDS COMMITTEE OF THE SAE BRAKE FORUM STEERING COMMITTEE Copyright SAE International Provided by IHS under license with SAENot for ResaleNo reproduction or networking permitted without license from IHS-,-,-
