1、 _ SAE Technical Standards Board Rules provide WKDW7KLVUHSRUWLVSXEOLVKHGE6$(WRDGYDQFHWKHVWDWHRIWHF KQLFDODQGHQJLQHHULQJVFLHQFHV7KHXVHRIWKLVUHSRUWLV entirely voluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefrRPLVWKHVROHUHVSRQVLEL
2、OLWRIWKHXVHU SAE reviews each technical report at least every five years at which time it may be revised, reaffirmed, stabilized, or cancelled. SAE invites your written comments and suggestions. Copyright 2016 SAE International All rights reserved. No part of this publication may be reproduced, stor
3、ed 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: +1 724-776-4970 (outside USA) Fax: 724-776-0790
4、Email: CustomerServicesae.org SAE WEB ADDRESS: http:/www.sae.org SAE values your input. To provide feedback on this Technical Report, please visit http:/www.sae.org/technical/standards/J2976_201602 SURFACE VEHICLE RECOMMENDED PRACTICE J FEB2016 Issued 2016-02 Speedometer and Odometer Systems for On-
5、Highway Vehicles RATIONALE This document has been developed to update recommended on-highway vehicle speedometer and odometer system performance for on-highway vehicles. 1. SCOPE This recommended practice is intended to provide industry technical personnel with an overview of vehicle speedometer sys
6、tem accuracy and offset requirements and odometer system accuracy requirements. Speedometer and odometer systems covered by this document are integrated into a vehicles electrical and electronics system, assembled directly into the vehicle by the OEM, and use rotational data from at least one vehicl
7、e wheel that is appropriately converted into longitudinal vehicle speed and distance traveled information. This standard is limited to radial ply tires on new (as manufactured) cars, light trucks, and medium duty trucks. Other methods for measuring vehicle speed and distance traveled may be used pro
8、vided they meet the performance recommendations herein. Any local market regulatory requirements must be met and shall supersede this document. Service parts are beyond the scope of this recommended practice. 2. REFERENCES 2.1 Applicable Documents The following publications form a part of this speci
9、fication to the extent specified herein. Unless otherwise indicated, the latest version of SAE publications shall apply. 2.1.1 SAE Publications Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Canada) or +1 724-776-4970 (outside U
10、SA), www.sae.org. SAE J1059 Speedometer Test Procedure SAE J1226 Electric Speedometer Specification - On Road SAE J678 Speedometers and Tachometers - Automotive SAE J862 Factors Affecting Accuracy of Mechanically Driven Automotive Speedometer-Odometers SAE J966 Test Procedure for Measuring Passenger
11、 Car Tire Revolutions Per Mile SAE J1025 Test Procedures for Measuring Truck Tire Revolutions Per Kilometer/Mile SAE INTERNATIONAL - FEB2016 Page 2 of 3 3. VEHICLE SPEEDOMETER AND ODOMETER SYSTEM 3.1 Types of Speedometer and Odometer Systems Most current speedometer and odometer systems use sensor d
12、ata based on tire rotation. This parameter is related to distance and time, and is converted into vehicle speed. 3.2 Tire Rotation Sensor Based System Block Diagram Passenger car tire parameters shall be measured using the procedure outlined in SAE J966. Truck tire parameters shall be measured using
13、 the procedure outlined in SAE J1025. 4. ACCURACY 4.1 Sources of Inaccuracy Tire revolutions per mile are subject to variations described in SAE J966 and SAE J1025. Inaccuracies due to electronic sensor tolerance and signal processing are negligible compared to tire parameter variation. 4.2 Recommen
14、ded Tolerance By using tire and vehicle performance tests described in SAE J966 and SAE J1025, which account for sources of speedometer and odometer system component variability and tolerance stack-up, combined with customer expectations (i.e., potential for complaints due to comparison to 3rd party
15、 GPS units), speedometer and odometer systems in a new vehicle can be evaluated in a repeatable and accurate way. This is done as follows. In a new vehicle equipped with new, OEM-specified tires (tire size, rim size, and tire inflation pressure), complete the warm-up procedures described in SAE J966
16、 or SAE J1025, as applicable. After warm-up, verify that tire inflation pressures are consistent with OEM specified values. If they are not, adjust the pressure of each tire as needed and proceed with the appropriate vehicle test. Note that for speedometer and odometer system evaluation, tire pressu
17、res specified in SAE J966 and SAE J1025 are superseded by OEM specified values. The recommended relationship between the speedometer calculated speed (VC) and the actual vehicle speed (VA) shall be 0.99VA VC 9 A at the test points specified in SAE J966 for passenger cars (i.e., 25 mph, 45 mph, and 6
18、5 mph) and SAE J1025 for trucks (i.e., 45 mph). Note: VC is the calculated vehicle speed that is sent to the speedometer display and does not include, for example, speedometer pointer display error introduced by stepper motor position variation. The recommended odometer tolerance shall be within +/-
19、 2.5% of actual distance traveled. These recommendations are valid unless regulatory requirements in a particular market specify otherwise. Tire Parameters Signal Processing and Algorithm Sensor Location: x Wheel Speed x Transfer Case x Transmission Output Shaft x Others Speedometer Display Odometer
20、 Display INPUTS OUTPUTNPUTS SAE INTERNATIONAL - FEB2016 Page 3 of 3 5. OTHER CONSIDERATIONS 5.1 Tamper Resistance Odometer indication and calibration shall be highly tamper resistant such that changes can be performed only by an OEM authorized service technician or by someone that would be defined a
21、s a hacker. 5.2 Vehicle maximum speed shall be less than or equal to the maximum speedometer display speed. 5.3 The Odometer should be capable of displaying a numeric value of 999,999 kilometers or miles, depending on the market. 6. SPEEDOMETER / ODOMETER SYSTEM TEST PROCEDURES Vehicle manufacturers
22、 shall determine a nominal system configuration from which the speedometer and odometer system performances can be validated, subject to the tolerances specified herein. Dynamic tire parameters should be measured using an SAE recommended practice. 7. NOTES 7.1 Revision Indicator A change bar (l) loc
23、ated in the left margin is for the convenience of the user in locating areas where technical 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, nor in documents that contain editorial changes only. PREPARED BY THE SAE ODOMETER AND SPEEDOMETER SYSTEMS STANDARDS COMMITTEE
