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This standard is prepared in accordance with the rules given in GB/T 1.1-2009.
This standard replaces JT/T 721-2008 Requirements and test methods of electromagnetic retarder for the use of bus. The following main technical changes have been made with respect to JT/T 721-2008:
——The content of "General requirements" for retarder has been added (see Clause 4);
——The "independent brake of retarder" has been modified to "independent brake of retarder in full gear" (see 5.1, 5.2 and 5.3 herein, 5.1, 5.2 and 5.3 in 2008 Edition);
——The "retarder quickly enters working state" has been modified to "retarder quickly enters full gear working state" (see 6.2 herein, 6.2.1.2 in 2008 Edition);
——The test procedures have been modified (see 6.2, 6.3 and 6.4 herein; 6.2.1, 6.2.2 and 6.2.3 in 2008 Edition);
——The content of “Test conditions” has been modified (see 6.1 herein; 6.1 in 2008 Edition);
——The "rotor operating temperature shall not be higher than 450°C" has been deleted (see 5.2.1 in 2008 Edition);
——The part of bench test in the heat fade test has been deleted (see 6.2.2.1 in 2008 Edition).
This standard was proposed by and is under the jurisdiction of Subcommittee on Bus of National Technical Committee on Automobiles of Standardization Administration of China (SAC/TC 114/SC 22).
The previous edition of this standard is as follows: JT/T 721-2008.
Requirements and test methods of electromagnetic retarder for the use of bus
1 Scope
This standard specifies the performance requirements and test methods for electromagnetic retarder for bus.
This standard is applicable to buses with more than 22 passengers (excluding driver) and a maximum design total mass exceeding 5,000 kg. It may serve as a reference for other types of buses.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated reference, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 2408 Plastics — Determination of burning characteristics — Horizontal and vertical test
GB/T 3730.1 Motor vehicles and trailers — Types — Terms and definitions
GB/T 3730.2 Road vehicle — Masses — Vocabulary and codes
GB/T 12534 Motor vehicles — General rules of road test method
GB/T 26572 Requirements of concentration limits for certain restricted substances in electrical and electronic products
QC/T 29106 Technical specification of automobile wire harness
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3730.1 and GB/T 3730.2 shall apply.
3.1
electromagnetic retarder
device that uses magnetoresistance (e.g. eddy current, hysteresis) generated by rotating parts under the action of magnetic field to provide braking efficiency for vehicles independently
4 General requirements
4.1 Electromagnetic retarder (hereinafter referred to as "retarder") shall have a controller local area network (CAN bus) interface or an interface linked with vehicle antilock brake system (ABS). When ABS detects the brake lock of the vehicle, the retarder controller shall be able to automatically turn off the working power supply of the retarder; when the ABS brake lock is released, the retarder shall automatically return to working state.
4.2 The retarder shall be set in a working gear corresponding to its braking torque, and the braking torque of the first gear shall not be greater than 1/2 of the maximum braking torque of the retarder.
4.3 The technical conditions of retarder wire harness shall meet the requirements of QC/T 29106.
4.4 The flame retardant grade of retarder wire harness and wrapping material shall meet V-0 requirement of GB/T 2408, and temperature adaptability shall be -40°C ~ 125°C.
4.5 The limit requirements of restricted substances for electronic components of retarder shall meet GB/T 26572.
4.6 The control mode of retarder is classified into manual control and foot control. If manual control is adopted, the manual switch shall be installed at a position convenient for the driver to operate; if foot control is adopted, ensure that the retarder works before the service brake.
5 Performance requirements
5.1 Break performance
The test vehicle runs at a constant speed of 50 km/h on a flat road, and the retarder is independently braked in full gear. When the test vehicle speed is 30 km/h, the deceleration (a) shall meet the requirements of 0.62 m/s2 ≤ a ≤ 1.0 m/s2 or the deceleration duration (t) shall meet the requirements of 5.6 s ≤ t ≤ 9.0 s.
5.2 Heat fade performance
After the test vehicle runs continuously at a speed of 50 km/h for 12 min under the action of independent brake of retarder in full gear, the brake performance shall not be less than 40% of the deceleration specified in 5.1 or not higher than 2.5 times of the specified brake time.
5.3 Repeatability
The test vehicle runs at a speed of 50 km/h under the action of independent brake of retarder in full gear. After the retarder works continuously in the highest gear for 12 min, it stops working for 18 min as a cycle. The performance of the retarder after 10 cycles shall meet the requirements of 5.1 and 5.2.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 General requirements
5 Performance requirements
6 Test methods
ICS 43.040.40
T 24
备案号：
JT
中华人民共和国交通运输行业标准
JT／T 721—2017
代替JT／T721—2008
客车电涡流缓速器
装车性能要求和试验方法
Requirements and test methods of
electromagnetic retarder for the use of bus
2017-09-29发布 2018-02-01实施
中华人民共和国交通运输部 发布
前言
本标准按照GB／T 1.1—2009给出的规则起草。
本标准代替JT／T 721—2008《客车电涡流缓速器装车性能要求和试验方法》。本标准与JT／T 721—2008相比，主要技术变化如下：
——增加了对缓速器“一般要求”的内容(见第4章)；
——将“缓速器单独制动”改为“缓速器全挡单独制动”(见5.1、5.2、5.3，2008年版的5.1、5.2、5.3)；
——将“缓速器快速进入工作状态”改为“缓速器快速进入全挡工作状态”(见6.2，2008年版的6.2.1.2)；
——修改了试验步骤(见6.2，6.3，6.4，2008年版的6.2.1，6.2.2，6.2.3)；
——修改了“试验条件”的内容(见6.1，2008年版的6.1)；
——删除了“转子工作温度不高于450℃(见2008年版的5.2.1)；
——删除了热衰退试验中的台架试验部分(见2008年版的6.2.2.1)。
本标准由全国汽车标准化技术委员会客车分技术委员会(SAC／TC1 14／SC22)提出并归口。
本标准所替代标准的历次版本发布情况为：JT／T 721—2008。
客车电涡流缓速器
装车性能要求和试验方法
1 范围
本标准规定了客车电涡流缓速器装车性能要求和试验方法。
本标准适用于可载乘员数(不包括驾驶员)多于22人，且最大设计总质量超过500g的客车。其他客车可参照使用。
2 规范性引用文件
下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。
GB／T 2408 塑料 燃烧性能的测定 水平法和垂直法
GB／T 3730.1 汽车和挂车类型的术语和定义
GB／T 3730.2 道路车辆 质量 词汇和代码
GB／T 12534 汽车道路试验方法通则
GB／T 26572 电子电气产品中限用物质的限量要求
QC／T 29106 汽车电线束技术条件
3 术语和定义
GB／T 3730.1和GB／T 3730.2界定的以及下列术语和定义适用于本文件。
3.1
电涡流缓速器 electromagnetic retarder
利用旋转部件在磁场作用下所产生的磁阻(例如电涡流、磁滞)为车辆单独提供制动效能的装置。
4 一般要求
4.1 电涡流缓速器(以下简称“缓速器”)应具有控制器局域网络(CAN总线)接口或与车辆防抱死制动系统(ABS)联动的接口。当ABS监测到车辆制动抱死时，缓速器控制器应能自动关断缓速器的工作电源；当ABS制动抱死解除时，缓速器应自动恢复工作。
4.2 缓速器应设置与其制动力矩相应的工作挡位，第一挡的制动力矩不大于缓速器最大制动力矩的1／2。
4.3 缓速器线束技术条件应满足QC／T 29106的要求。
4.4 缓速器线束和包裹材料阻燃等级应满足GB／T 2408的V-0要求，温度适应性应为－40℃～125℃。
4.5 缓速器电子元器件的限用物质的限量要求应满足GB／T 26572。
4.6 缓速器控制方式分为手控和脚控两种。若采用手控方式，手控开关应安装在便于驾驶员操作的位置；若采用脚控方式，应保证缓速器先于行车制动器工作。
5 性能要求
5.1 制动性能
试验车辆在平坦路面上以50km／h的速度匀速行驶，缓速器全挡单独制动，至试验车辆速度为30km／h时，减速度(a)应符合0.62m／s2≤a≤1.0m／s2的要求或减速时间(t)应符合5.6s≤t≤9.0s的要求。
5.2 热衰退性能
试验车辆在缓速器全挡单独制动作用下以50km／h的速度持续行驶12min后，按5.1的要求试验，制动性能应不低于5.1规定的减速度的40％或不高于规定制动时间的2.5倍。
5.3 重复性
试验车辆在缓速器全挡单独制动作用下以50km／h速度行驶，缓速器以最高挡位持续工作12min后，停止工作18min为1个循环。经过10个循环后缓速器的性能应符合5.1和5.2的规定。
6 试验方法
6.1 试验条件
6.1.1 试验过程中，风速小于5m／s，环境温度不超过35℃。
6.1.2 试验路面应具有良好的附着性能。
6.1.3 车速测试仪器精度不低于±1％。
6.1.4 试验车辆满足GB／T 12534的要求。
6.2 制动性能试验
试验步骤如下：
a) 试验车辆进行充分预热行驶；
b) 试验车辆速度达到50km／h后，使缓速器快速进入全挡工作状态；
c) 测量并记录速 度从50km／h到30km／h的减速时间；
d) 沿反方向重复b)和c)；
e) 试验车辆以50km／h的速度匀速行驶30min缓速器不工作；
f) 以b)至e)为1个循环，共进行2个循环。
试验结果按式(1)计算，应符合5.1的规定。
(1)
式中：a——减速度，单位为米每二次方秒(m／s2)；
t——各次减速时间的平均值，单位为秒(s)。
6.3 热衰退性能试验
试验步骤如下：
a) 试验车辆在试验道路上使用缓速器全挡制动，以50km／h的速度持续行驶12min；
b) 按6.2中b)至c)进行；
c) 试验车辆以50km／h的速度匀速行驶30min，缓速器不工作；
d) 以a)至c)为1个循环，共进行5个循环。
试验结果按式(1)计算，应符合5.2的规定。
6.4 重复性试验
试验步骤如下：
a) 试验车辆在试验道路上使用缓速器全挡制动，以50km／h的速度持续行驶12min；
b) 试验车辆以50km／h的速度匀速行驶18min，缓速器不工作；
c) 以a)至b)为1个循环，共进行10个循环；
d) 10个循环结束后，试验车辆在试验道路上使用缓速器全挡制动，以50km／h的速度持续行驶12min，按6.2中b)至c)进行，试验结果按式(1)计算，应符合5.2的规定；
e) 缓速器不工作 且试验车辆以50km／h的速度匀速行驶18min后，按6.2中b)至c)进行，试验结果按式(1)计算，应符合5.1的规定。
