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 ther
2、efrom, is the sole responsibility of the user.” 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 2015 SAE International All rights reserved. No part of this
3、publication may 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: +1 724-776-49
4、70 (outside USA) Fax: 724-776-0790 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/J1808_201506 SURFACE VEHICLE STANDARD J1808 JUN2015 Issued 1989-10 Revised 2015-
5、06 Superseding J1808 OCT1989 Vacuum Power Assist Brake Booster Test Procedure RATIONALE This standard is being revised because the state of the art for vacuum boosters has changed significantly since it was last published. 1. SCOPE This document applies to direct acting vacuum power assist brake boo
6、sters only, exclusive of the master cylinder or other brake system prime mover devices for passenger cars and light trucks 4500 kg GVW (10 000 lb). It specifies the test procedure to determine minimum performance and durability characteristics. 1.1 Purpose This document specifies standards for direc
7、t acting vacuum power assist brake boosters of current established designs. It is applicable to assemblies from commercial production, after production shipment, and remanufacture. 2. REFERENCES 2.1 Applicable Publication The following publication forms a part of the specification to the extent spec
8、ified herein. Unless otherwise indicated the latest revision of SAE publications shall apply. JASO Standards C452:2005 “Automotive parts Vacuum servo unit” 2.1.1 SAE Publication Available from SAE International, 400 Commonwealth Drive, Warrendale, PA 15096-0001, Tel: 877-606-7323 (inside USA and Can
9、ada) or +1 724-776-4970 (outside USA), www.sae.org. 3. DEFINITIONS In order to establish and maintain a continuity of discussion throughout this document, the following definition of terms will be used. NOTE: Figure 1 for illustration of terms as applied to a typical input-output force curve. 3.1 RE
10、LEASED The unapplied, fully returned state with no force on the input push rod (with or without vacuum). SAE INTERNATIONAL J1808 Revised JUN2015 Page 2 of 10 3.2 POISE The condition of placing the control valve in a steady state of force equilibrium so that the vacuum power assist brake booster is n
11、either fully applied, nor fully released. 3.3 CUT-IN The input force required to actuate the valving and produce an output force. 3.4 POWER SLOPE The ratio of change in output force to change in input force in the area of performance above the initial rise and below the vacuum run-out point. Figure
12、1 - Typical input-output (X-Y) curve SAE INTERNATIONAL J1808 Revised JUN2015 Page 3 of 10 3.5 POWER BOOST The output force minus the input force for a given vacuum level and with the maximum available pressure differential across the power piston(s), and at 80% of the usable output stroke of the boo
13、ster. 3.6 VACUUM RUN-OUT LINE The line defined by two or more points on the input-output curve beyond the input force at which all available pressure differential exists across the power piston(s). 3.7 VACUUM RUN-OUT POINT The point defined by the intersection of the power slope line and the vacuum
14、run-out line. 3.8 INITIAL RISE The intersection of a vertical line through the cut-in point and the power slope line. 3.9 HYSTERESIS The difference between apply and release input forces at a given output force during the power slope. 3.10 RETURN CUT-OUT The input force at which the output force dro
15、ps to zero or some specified level during release. 3.11 BOOSTER SIZE Described by the maximum outside diameter, power boost at 80 kPa (23.62 in Hg) vacuum, and at 80% of the usable output stroke, and whether single or tandem. Single Tandem 4. TEST APPARATUS The basic apparatus shall be that shown an
16、d as arranged in Figure 2 or equivalent. The apparatus shall operate per Section 4 and as called for in Section 6. It is desirable to have the test apparatus portable to facilitate cold, hot, and room temperature testing. 4.1 Force Absorbing Mechanism The force absorbing mechanism shall be connected
17、 to the vacuum power assist brake booster front housing. This mechanism shall be capable of absorbing a minimum of 150% of booster vacuum run-out point output force, or 9000 N (2000 lb) output force, whichever is greater. SAE INTERNATIONAL J1808 Revised JUN2015 Page 4 of 10 4.1.1 Recommended Output
18、Force and Stroke Relationship It is recommended that the force absorbing mechanism be capable of restricting the output force and stroke relationship to the shaded are of Figure 3. 4.1.2 Optional Output Force and Stroke Relationship It is recommended that the force absorbing mechanism is not a rigid
19、 fixture, however optionally a rigid fixture which limits output rod stroke to 50% 20% of its full travel may be used. Use of a rigid force absorbing fixture will produce lower frictional losses and lower hysteresis values. 4.2 Stroking Mechanism The stroking mechanism shall contain a mounting plate
20、 to which the booster is attached in a manner similar to how it would be mounted in the vehicle. The mounting plate must be sufficiently rigid such that its deflection does not contribute to the input pushrod travel measurements. The actuator shall be compatible with the input push rod(s) of the boo
21、ster and shall operate coaxially within 3 deg of the longitudinal axis of the booster. The fixture shall be constructed such that full release of the booster is obtained. The stroking mechanism may accommodate multiple boosters if desired, and shall be designed so that it does not apply tensile forc
22、e to input push rod. Means must be provided for the stroking mechanism to stroke the booster both singly and cyclically. 4.2.1 For single stroke operation, the mechanism shall be capable of generating input push rod forces up to 4500 N (1000 lb) at its maximum travel and holding this position. 4.2.2
23、 For cyclic operation, the stroking mechanism shall be capable of applying the input push rod to generate 80% 10 of the vacuum run-out point output force at a rate that can be adjusted from 250 to 1000 apply/release cycles per hour. The input push rod shall be stroked forward at a smooth rate and al
24、lowed to return rapidly to its fully released position. The time cycle shall be adjusted to allow maximum time for forward stroking while insuring that the input push rod returns to the fully released position before the start of the next forward stroke. 4.2.3 In 6.11 structural test, utilize a suit
25、able compression test apparatus for performing structural test. 4.3 Instrumentation 4.3.1 A 4 channel data acquisition and recording system compatible with 4.3.2 and 4.3.3. This system must be capable of providing output in standard digital format such as CSV ASCII. If not the system must be able to
26、 produce plots of each of the 4 channels vs time base and also any two of the channels against each other. 4.3.2 Force transducers or equivalent measuring devices to measure input and output push rod forces of 0 to 4500 N (0 to 1000 lb) and 0 to 9000 N (0 to 2000 lb) respectively. Overall accuracy 1
27、/2% of full scale. 4.3.3 Linear transducers or equivalent measuring devices must be provided to measure: 4.3.3.1 Input push rod travel of 0 to 50 mm (0 to 2 in). 4.3.3.2 Output push rod travel of 0 to 50 mm (0 to 2 in). Overall accuracy of 1/2% of full scale. 4.3.4 Vacuum gage or equivalent capable
28、of measuring 0 to 100 kPa 1/2% full scale (0 to 30 in Hg). SAE INTERNATIONAL J1808 Revised JUN2015 Page 5 of 10 4.4 Environmental Equipment 4.4.1 Hot Test Chamber Shall be provided having sufficient capacity to house test apparatus fixtures. The modulated air source for internal use in the booster s
29、hall be at room temperature or at test chamber temperature as specified by the manufacturer. A suitable thermostatically controlled heating system is required to maintain a uniform atmosphere at the desired temperature up to 85 C 3 (185 F 5). Heaters shall be shielded to prevent direct radiation to
30、the booster. 4.4.2 Cold Test Chamber Shall be provided having sufficient capacity to house test apparatus fixtures. The modulated air source for internal use in the booster shall be at room temperature or at test chamber temperature as specified by the manufacturer. A suitable thermostatically contr
31、olled cooling system is required to maintain a uniform atmosphere at the desired temperature down to 40 to 43 C (40 to 45 F). 4.5 Vacuum Source A vacuum source including all lines and fittings shall be capable of maintaining a set vacuum level of 80 kPa 1.7 (23.62 in Hg 0.5) during the apply portion
32、 of all cyclic tests and as specified for single stroke operation. 5. TEST SAMPLE The booster shall come from one of the sources described in Section 1. It shall be new or not used after rebuild, and it shall not be disassembled prior to testing. A single unit should be used for all testing from 6.1
33、 to 6.6. 6. TEST SETUP AND PROCEDURE Tests shall be conducted in the sequence shown and at room temperature except where otherwise specified. The booster shall not be disassembled until after all tests are completed or unless testing is discontinued. 6.1 Initial Evaluation This phase of the test is
34、for the purpose of obtaining a performance profile of the booster without disrupting or otherwise altering its parts or integrity. 6.1.1 Initial Setup Install the booster on the mounting plate, as shown in Figure 2, and tighten mounting fasteners to the recommended torque. Make certain that the inpu
35、t push rod is properly aligned with the longitudinal axis of the booster within 3 deg. Adjust the apply actuator and/or input push rod to allow the booster to return to a fully released position with zero preload on the input push rod. Attach the force absorbing mechanism to the front housing of the
36、 booster and adjust according to Figure 3. Install vacuum line and gage per 6.1.2 from the vacuum port to the vacuum source. Check valve location is optional as it is desirable that it is the same as the actual vehicle system to avoid unexpected restriction effects. SAE INTERNATIONAL J1808 Revised J
37、UN2015 Page 6 of 10 Figure 2 - Schematic of recommended setup Figure 3 - Recommended stroking performance curves for force absorbing mechanism 20406080100120020 40 60 80 1000OUTPUTPUSHROD FORCEPERCENTOFRUNOUTOUTPUT PUSHROD TRAVEL PERCENT OF TOTAL STROKESAE INTERNATIONAL J1808 Revised JUN2015 Page 7
38、of 10 6.1.2 In cases where the booster is supplied with an integrally mounted check valve at the booster vacuum port or an in-line check valve, the vacuum supply line must be connected between the check valve and the front shell of the booster. This will insure that the vacuum level indicated on the
39、 external gage is the actual vacuum level inside the booster shell. In this case, the check valve should be vented to atmosphere. 6.1.3 Data acquisition Connect the input force, output force, input travel transducers to the data acquisition system. 6.2 Apply-Release 6.2.1 Power Evacuate the booster
40、to 80 kPa 1.7 (23.62 in Hg 0.5). Apply force to the input push rod at a rate of 135 N/s 90 (30 lb/s 20). After the apply force generates 120 to 150% of the vacuum run-out point output force, release the force to the input push rod at the same rate and allow the booster to return to a fully released
41、condition. 6.2.2 Reserve Apply-Release Capability Evacuate the booster to 80 kPa 1.7 (23.62 in Hg 0.5) and close the vacuum shut-off valve. Apply force to the input push rod at a rate of 135 N/s 90 (30 lb/s 20) to generate 25 to 30% of the vacuum run-out point output force and 25 to 35% of the usabl
42、e output stroke (note the input force used). Hold for 15 s, and return and input push rod force to zero. Repeat this apply-release cycle, using the same input force, and record, to the nearest cycle, the number of cycles until power assist is reduced to zero. 6.2.2.1 “No Power“ Apply-Release With va
43、cuum supply disconnected and vacuum port vented to atmosphere, stroke booster until all internal vacuum is depleted. Repeat procedure 6.2.1 using the same input values. 6.3 Vacuum Leak Check Install vacuum gage at the vacuum port to measure vacuum level in the booster. The volume of the vacuum lines
44、 between the booster and the shutoff valve including the vacuum gage, should not exceed 100 cm3(6 in3). 6.3.1 Fully Released Evacuate the booster to 80 kPa 1.7 (23.62 in Hg 0.5), and allow to stabilize for a minimum of 15 s. With zero force on the input push rod, close the vacuum shutoff valve and m
45、easure the drop in vacuum level in the unit after 15 s. 6.3.2 Poise Evacuate the booster to 80 kPa 1.7 (23.62 in Hg 0.5). Apply and maintain a steady force to the input push rod to generate 25 to 30% of the vacuum run-out point output force, and allow to stabilize for 15 s minimum. Close the vacuum
46、shutoff valve and measure the drop in vacuum level in the unit after 15 s. 6.3.3 Run-Out Evacuate the booster to 80 kPa 1.7 (23.62 in Hg 0.5). Apply and maintain a steady force to the input push rod to generate 120 to 150% of the vacuum run-out point output force and allow to stabilize for 15 s mini
47、mum. Close the vacuum shutoff valve and measure the drop in vacuum level in the booster after 15 s. 6.4 Apply and Release Response Adjust the output force absorbing mechanism to provide 65 to 75% of the usable output stroke at 125 to 135% of vacuum run-out point output force. Maintain the vacuum lev
48、el at 80 kPa 1.7 (23.62 in Hg 0.5). SAE INTERNATIONAL J1808 Revised JUN2015 Page 8 of 10 6.4.1 Apply Response Apply an input force to generate 150% minimum of vacuum run-out point output force at a rate that 130% minimum of input run-out force is obtained in 0.25 s or less. Maintain the output force
49、 above 150% for a minimum of 2 s. 6.4.2 Release Response Release the input force so that the applying device retracts faster than the input rod. 6.4.3 Record the input and output forces versus time for the respective apply and release tests. 6.5 Usable Output Stroke and Input Travel Loss 6.5.1 Usable Output Stroke It is the intent
