车用尿素结晶堵塞了是怎么回事?

日期:2020-12-23 | 人气:138

1、车用尿素溶液催化器结构设计的缺陷

1. Defects in structural design of automotive urea solution catalyst

早期生产的车辆经常出现尿素喷嘴到SCR催化器之间的距离过短,当尿素被喷出后还没有来得及气化就到达催化剂载体,故而形成结晶;还有尿素喷嘴安装基座焊接角度以及催化器封装等不符合要求。

In early production vehicles, the distance between urea nozzle and SCR catalytic converter is too short. When urea is sprayed out, it reaches the catalyst carrier before gasification, so crystallization is formed; moreover, the welding angle of urea nozzle mounting base and catalytic converter packaging do not meet the requirements.

2、车用尿素溶液喷嘴的雾化效果或喷嘴失效

2. Atomization effect or nozzle failure of vehicle urea solution nozzle

常见车型选用的后处理SCR系统可分为无气助型和有气助型两种。一般无气助的尿素喷射工作压力相对较高,所以经常出现喷嘴阀针关闭不严,导致在不该工作的低排温阶段依然工作,尿素无法高温水解以致快速结晶,有气助的尿素喷嘴是常开型,其雾化是靠气压来辅助的,如尿素泵气压管路出现故障或喷嘴在高温下炸裂等都会造成喷射雾化不良,以致造成结晶堵塞。

There are two types of post-treatment SCR systems for common vehicle models, i.e. non air assisted SCR system and air assisted SCR system. Generally, the working pressure of urea injection without air assistance is relatively high, so it often occurs that the nozzle valve needle is not closed tightly, which leads to still working in the low discharge temperature stage when it should not work. Urea can not be hydrolyzed at high temperature, resulting in rapid crystallization. The urea nozzle with gas assistance is normally open, and its atomization is assisted by air pressure, such as the failure of the air pressure pipeline of the urea pump or the nozzle cracking at high temperature As a result, the spray atomization is poor and the crystallization is blocked.

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3、车辆熄灭后的尿素泵清空不彻底

3. The urea pump is not completely emptied after the vehicle goes out

由于车辆停止工作后车用尿素溶液泵和管路路中任残留有液体存在,所以车辆关闭点火开关后都需执行清空工作防止结晶或冻结。

Since there is any residual liquid in the vehicle urea solution pump and pipeline after the vehicle stops working, it is necessary to empty the vehicle after turning off the ignition switch to prevent crystallization or freezing.

4、车用尿素溶液泵滤芯没有定期更换

4. The filter element of vehicle urea solution pump is not replaced regularly

所有的尿素泵都有过滤器或滤芯,必须定期清理或更换,否则时间久了会导致堵塞或破损以致失去过滤作用,必然引起系统工作失调。如果在添加尿素时不慎将灰尘带入灌内,若过滤功能失效后很容易造成堵塞喷嘴,一般喷嘴有3-4孔,假如堵塞了一两个孔必然就会出现雾化不良而引起结晶。

All urea pumps have filters or filter elements, which must be cleaned or replaced regularly. Otherwise, if the time is too long, it will lead to blockage or damage, resulting in the loss of filtration function, which will inevitably cause the system to work out of order. If the dust is brought into the tank when adding urea, it is easy to block the nozzle if the filtration function fails. Generally, the nozzle has 3-4 holes. If one or two holes are blocked, there will be bad atomization and crystallization.

5、其他车用尿素溶液外部传感器和执行器元件的性能故障或损坏

5. Performance failure or damage of other external sensors and actuators of vehicle urea solution

比如当排气温度传感器出现性能性故障时,可能实际排气温度是100摄氏度,而传感器反馈给电脑温度是180摄氏度,就会导致系统提前喷射尿素,尿素喷射在低温的排气中无法得到水解气化,自然会在催化器载体处形成结晶,久而久之形成坚硬的尿素结晶体化合物。

For example, when the exhaust temperature sensor has a performance failure, the actual exhaust temperature may be 100 ℃, while the temperature fed back by the sensor to the computer is 180 ℃, which will cause the system to inject urea in advance. The urea injection can not get hydrolysis gasification in the low-temperature exhaust gas, which will naturally form crystals at the catalyst carrier and form hard urea crystal compounds over time.

6、车辆使用劣质柴油以及工作环境恶劣引起催化剂失效

6. The catalyst failure is caused by the use of inferior diesel oil and bad working environment

SCR系统的催化剂是促进尿素溶液在高温下水解气化分解成的氨与废气中的NOx进行化学反应的,它对柴油中硫含量有很高的技术要求,高温形成的硫化物对催化器有不可逆的破坏作用,所有一旦催化器失效就会引起尾气超标而限制发动机动力输出。

The catalyst of SCR system is to promote the chemical reaction between ammonia decomposed from urea solution and NOx in exhaust gas at high temperature. It has high technical requirements for sulfur content in diesel. Sulfide formed at high temperature has irreversible damage to the catalyst. Once the catalyst fails, the exhaust gas will exceed the standard and limit the engine power output.