158 汽车热管理阀与水泵用什么改性尼龙
热管理系统的塑料件
新能源汽车的热管理系统（电池冷却、电机冷却、座舱空调）比传统车复杂得多，
塑料件也更多：电子多通水阀（控制冷却液流向）、电子水泵壳体与叶轮、膨胀水壶、冷却液管路接头、温度传感器座。
共同要求：耐冷却液、耐温（-40℃ 到 120℃）、尺寸稳定、耐水解。耐冷却液是第一门槛。
现场还原：一次叶轮断裂报告的追根
前年冬天，一家水泵厂的售后收到批量反馈：装在某新能源车型上的电子水泵叶轮运转异响，拆检发现叶片根部开裂。断裂件的叶片根部有白色疲劳弧线，典型的机械疲劳特征。
第一反应是冷却液里进了杂质，拆开同批水泵检查，叶轮腔内干净，排除了磨粒因素。
再往深挖，材料测试揭开了真相：那批叶轮用了新切换的牌号，常温性能与前牌号相当，但八十度冷却液环境下的弯曲疲劳强度低了近两成。
新能源车型的水泵工况比燃油车严酷——冷却液温度常年偏高且流量随需求频繁变化，叶轮承受的是变载荷疲劳。低疲劳牌号在燃油车上能用，在新能源热管理的工况下撑不满设计寿命。
整改很快：换回高疲劳牌号加叶片根部圆角加大一档，双保险。半年后市场再无同类投诉。水泵厂把这次的断裂件和合格件并排摆在展柜里，新员工培训第一课就是看这对叶轮——同样的图纸，不同的材料，两年的寿命差。
耐冷却液的老化机理
冷却液通常是乙二醇水溶液 + 缓蚀剂包。PA 在热乙二醇水溶液中会发生水解——这是热管理件最主要的失效机理。
温度越高，水解越快：80℃ 下 1000 小时的衰减和 120℃ 下 200 小时的衰减相当。
所以热管理件必须走耐水解体系（碳二亚胺类抗水解剂 + 耐热稳定剂），且验证要按实际工作温度而不是常温做。
多通阀的特殊要求
电子多通阀是热管理系统的核心控制件——内部有旋转阀芯，要在冷却液中长期转动并保持密封。
要求：耐冷却液 + 耐磨 + 尺寸稳定 + 低摩擦。
阀芯走 PPS 或 PPA（耐温耐水解），阀体走耐水解 PA66-GF30。
关键失效模式是阀芯卡滞——结垢、磨损或尺寸变化都会导致卡滞，这是热管理系统的主要故障。
水泵叶轮和壳体
电子水泵的叶轮走 PPS 或耐水解 PA66-GF30——
要耐 90-120℃ 冷却液长期浸泡 + 高速旋转的离心力 + 汽蚀。
壳体走耐水解 PA66-GF30。汽蚀是水泵叶轮的特殊失效模式——气泡破裂的冲击会剥离材料表面，要走高韧性高硬度的体系。
另外，叶轮的动平衡要控制（和电机一样影响 NVH）。
膨胀水壶和管路
膨胀水壶要半透明（看液位）+ 耐冷却液 + 承压（通常 0.1-0.2 MPa）+ 耐温。
走 PA66 半透明牌号或 PP——和制动液壶的思路类似，但PA66 在热冷却液中的表现优于 PP。
管路接头走耐水解 PA66-GF30，快插接头的密封要按长期蠕变校核（PA 蠕变会让卡接力衰减）。
深一层：耐冷却液老化的机理比想象中复杂
冷却液对塑料的攻击是三条路径的叠加。第一条是乙二醇本身的攻击，乙二醇对多数工程塑料温和，这是冷却液回路大量使用塑料的前提。
第二条是添加剂的攻击，防冻液里的缓蚀剂、消泡剂、染料各有化学活性，某些牌号对特定缓蚀剂体系敏感，实测时要锁定冷却液品牌和型号，不同厂家的配方差异不小。
第三条是水解，冷却液里的水分在高温下引发聚酯类材料水解，尼龙类相对稳定，这也是水泵叶轮行业以 PA66 系为主力的原因之一。
多通阀是热管理回路里集成度最高的塑料件，阀体内的流道切换靠电机驱动阀片，阀片材料要耐磨耐冷却液，阀体要耐压密封，集成流道的结构让注塑模具复杂度倍增。
多通阀的失效模式里阀片卡滞占大头，卡滞的根因常是阀片溶胀或流道内的析出物堆积，材料端的析出控制比耐磨本身更关键，这条经验是多通阀厂商用售后数据换来的。
膨胀水壶看着简单，压力脉动加温度循环加冷却液的组合工况也不轻。水壶盖的压力阀座区域是薄弱位置，材料在蒸汽和液态的两相环境里交替工作，验证时要做压力循环加温度循环的复合试验。
延伸判断：热管理件的隐性变量
有三件最容易漏掉的隐性变量。一是冷却液的配方差异——不同主机厂的缓蚀剂包不同，对 PA 的影响差异很大，要用实际冷却液验证。
二是结垢——冷却液长期高温会结垢，影响阀芯和流道，要设计过滤或定期更换。
三是干烧——冷却液泄漏后水泵干转，温度会骤升，塑料件要有短时耐干烧的能力。
工程实测：4 条强制测试
测试1：冷却液浸泡 120℃ 1000 h。耐水解 PA66 拉伸保持 80%，通用 PA66 降至 48%——必须耐水解。
测试2：阀芯磨损（10 万次）。PPS 阀芯磨损 0.05 mm，PA66 阀芯 0.25 mm——阀芯优先 PPS。
测试3：汽蚀（500 h）。高韧性体系表面失重 8 mg，通用体系 35 mg——叶轮要抗汽蚀。
测试4：快插接头蠕变。PA66 卡接力 1000 h 后衰减 20%——设计要留余量。
边界声明
| 工况 | 推荐材料 |
|---|
| 多通阀阀芯 | PPS 或 PPA（耐磨 + 耐水解） |
| 阀体 / 水泵壳 | 耐水解 PA66-GF30 |
| 水泵叶轮 | PPS 或高韧性耐水解体系 |
| 膨胀水壶 | PA66 半透明牌号 |
| 管路快插接头 | 耐水解 PA66-GF30 + 蠕变余量 |
工程备忘
热管理件耐冷却液是第一条门槛——PA 在 120℃ 乙二醇水溶液中 1000 小时强度掉一半，必须走耐水解体系。多通阀阀芯优先 PPS（磨损量只有 PA66 的 1/5）。
实战案例：常见踩坑与正解
踩坑一：按传统汽车的思路选料，忽略了电气安全要求。正解：新能源车上的塑料件第一判据往往是电气性能——CTI（相比漏电起痕指数）、阻燃等级、耐电弧性，这些在传统车上不重要的指标在这里是硬门槛。踩坑二：只看阻燃等级，忽略了长期湿热下的电痕化。正解：阻燃是着火时的表现，CTI 是长期运行的表现——两者都要，高压件通常要求 CTI ≥ 600V 且阻燃 V-0，缺一项就是长期隐患。踩坑三：把电池的工况简单理解为"高温"，忽略了冷热交变和湿热。正解：电池包内是温度交变 + 湿度变化 + 冷却液的复合环境，验证要做温度冲击 + 湿热 + 冷却液相容性的组合测试。这三个坑都是量产前必须自查的清单。
追问三连：热管理件读者的三个高频问题
第一问：新能源热管理回路和燃油车冷却回路的选材差异在哪？温度更高、流量变化更频繁、回路更复杂。燃油车冷却液常年八十度上下，新能源回路的高温段超过九十度，塑料件的耐温等级和疲劳规格整体上调。
第二问：水泵叶轮用玻纤还是不加？加，含量二成五到三成是主流。叶轮要刚性撑住叶片形状，玻纤同时提升疲劳强度。但玻纤过多让叶轮变脆，石子击打泵体传来的冲击要靠韧性兜底，配方是平衡的艺术。
第三问：冷却液品牌和材料验证要绑定吗？要。售后市场的通用冷却液配方跨度大，原厂材料验证绑定原厂冷却液型号，通用型产品则按主流冷却液品牌做兼容矩阵。材料商的兼容数据库是这类项目的核心资产。
反向案例：一只被当作通用件卖的节温器壳体
有家售后配件厂把燃油车节温器壳体的图纸拿去配新能源车型的维修市场，装车三个月后批量渗漏，根因是新能源回路的温度和压力更高，壳体材料的耐压等级不足。售后配件不是低配的代名词，适配工况的材料才是正品。
增补：另外三个读者的实际问题
第四问：多通阀的阀片用什么料最稳？耐磨加低析出的复合体系是共识，阀片和阀体的摩擦副最好用同一供应商的配套牌号，两方数据的相容性有依据。跨供应商拼摩擦副，出了问题责任难分。
第五问：水泵的电寿命和机械寿命哪个先到？看叶轮轴承。滑动轴承方案的机械寿命是短板，滚动轴承方案电气寿命先到。叶轮材料在两种方案里的角色不同，前者偏耐磨，后者偏强度，选型前先确认轴承方案。
第六问：热管理集成模块会替代单件吗？趋势在走，多个阀和水泵集成一个模块后，塑料件的数量减少但单件复杂度上升。集成模块里的壳体流道件是未来几年的增量市场，模具和材料能力的门槛都在提高。
一组现场的观察
观察一，热管理件的售后投诉有季节规律。夏季高温段的投诉集中在耐压和密封，冬季低温段的投诉集中在启动卡滞，两个季节的失效机理不同，选材验证要两头都覆盖。
观察二，冷却液兼容正在成为招标硬项。越来越多整车厂的招标文件里写明兼容指定品牌冷却液，材料商的兼容数据库越厚，投标响应越快，这类隐形资产在比价时值真金白银。
收口的一组数字
数字一，关于水泵的转速边界。电子水泵电机的转速普遍在几千到一万之间，叶轮的线速度和转速成正比，耐磨验证的转速按最高工作转速上浮一档做。转速每上一档，材料的疲劳规格跟着上一档。
数字二，关于冷却液的温度上限。新能源热管理回路的高温段在九十度上下，部分高负荷工况短时超过一百。冷却液温度每升十度，材料的老化速率大约翻倍，这个化学规律决定了耐温等级不能省。
数字三，关于多通阀的集成度。主流多通阀的流道数量从三通走到了十一通，集成度翻了几番，阀体流道的复杂度让注塑模具成为核心竞争资产。阀体件的定点谈判里，模具能力是和材料能力并列的话题。
最后一句话
热管理是新能源车的命脉，回路上每一个塑料件都参与温度和压力的调度。把冷却液兼容和疲劳寿命两项数据备齐，就能在这个增量市场里站住位置。
附记
还有一点值得提醒：热管理回路里的塑料件在停机状态下会长时间存留冷却液，静态浸泡的老化比流动状态更严酷，验证方案里静态和动态两组都要有，只做动态会偏乐观。
结语
这三件事我们从不猜——选料这件事，越早问越省事。
这类件的选料与试模，可以一起聊。
158 What is used for automotive thermal management valves and water pumps? Modified nylon
Plastic parts for thermal management systems
The thermal management system of new energy vehicles (battery cooling, motor cooling, cabin air conditioning) is much more complex than traditional vehicles,
and more plastic parts: electronic multi-way valve (controls coolant flow direction), electronic water pump housing and impeller, expansion kettle, coolant pipeline connector, temperature sensor base.
Common requirements: coolant resistance, temperature resistance (-40°C to 120°C), dimensional stability, hydrolysis resistance. Coolant resistance is the first threshold.
On-site Restoration: Tracing the Root of an Impeller Fracture Report
In the winter before last, after-sales service at a pump factory received batch feedback: the impeller of an electronic water pump installed in a certain new energy vehicle made abnormal operating noises, and disassembly revealed cracks at the blade roots. The root of the broken blade showed white fatigue arcs, typical mechanical fatigue characteristics.
's first reaction was impurities entering the coolant. Disassembled and inspected the same batch of pumps, the impeller chamber was clean, eliminating abrasive factors.
Digging deeper, material testing revealed the truth: that batch of impellers used a newly switched grade, with room temperature performance comparable to the previous grade, but the bending fatigue strength at 80°C coolant was nearly 20% lower.
The water pump operating conditions for new energy vehicles are harsher than fuel vehicles—coolant temperature remains high year-round and flow rate fluctuates with demand, and the impeller suffers from variable load fatigue. Low fatigue grades work on fuel vehicles, but under new energy thermal management conditions, they cannot last their design life.
Quick rectification: Switching back to high fatigue grades plus enlarging the blade root fillet by one level, double protection. Six months later, there were no similar complaints in the market. The pump factory placed the broken and qualified parts side by side in the display case. The first lesson in new employee training was to look at this impeller—same blueprints, different materials, two years of service life.
Aging resistance mechanism of coolant
Coolant is usually ethylene glycol solution + corrosion inhibitor package. PA undergoes hydrolysis in hot ethylene glycol aqueous solution—this is the main failure mechanism of thermal management components.
The higher the temperature, the faster the hydrolysis: 1000 hours of degradation at 80°C is equivalent to 200 hours at 120°C.
Therefore, thermal management components must use a hydrolysis-resistant system (carbodiimide hydrolytic agents + heat-resistant stabilizers), and verification should be conducted at actual operating temperatures rather than room temperature.
Special requirements for multi-way valves
The electronic multi-way valve is the core control component of the thermal management system—it has a rotating valve core inside, must rotate continuously in the coolant and maintain sealing.
Requirements: coolant resistance + wear resistance + dimensional stability + low friction.
The valve core should be PPS or PPA (temperature and hydrolysis resistant), and the valve body should be hydrolysis-resistant PA66-GF30.
The key failure mode is core jamming—scaling, wear, or dimensional changes can all cause sticking, which is the main fault in the thermal management system.
Pump impeller and casing
Electronic pump impeller uses PPS or hydrolysis-resistant PA66-GF30 —
Must withstand long-term immersion in coolant at 90-120°C + high-speed centrifugal force + cavitation.
Housing should be hydrolyzed-resistant PA66-GF30. Cavitation is a special failure mode of the pump impeller—the impact from bubble bursting strips off the material surface, requiring a system with high toughness and hardness.
Additionally, the impeller's dynamic balance must be controlled (just like the motor, NVH is affected).
Expansion kettle and piping
expansion kettle should be semi-transparent (see level) + coolant resistant + pressure resistance (usually 0.1-0.2 MPa) + temperature resistant.
Use PA66 semi-transparent grade or PP—similar to brake fluid reservoirs, but PA66 performs better than PP in thermal coolant.
Pipe joints should be hydrolyzed-resistant PA66-GF30. The sealing of quick-plug joints should be checked by long-term creep (PA creep can weaken the relay force).
Deeper layer: The mechanism of coolant aging resistance is more complex than imagined .
The attack on plastics by coolant is a combination of three paths. The first is the attack on ethylene glycol itself, which is mild to most engineering plastics, which is the prerequisite for the heavy use of plastic in the coolant circuit.
The second is the attack on additives. The corrosion inhibitors, defoamers, and dyes in antifreeze each have chemical reactivity. Some grades are sensitive to specific corrosion inhibitor systems, so during actual testing, the coolant brand and model should be specified, as formulations vary significantly among manufacturers.
The third is hydrolysis. The moisture in the coolant causes polyester materials to hydrolyze at high temperatures, while nylon is relatively stable. This is one of the reasons why the pump impeller industry mainly uses PA66 series.
Multi-way valves are the most integrated plastic components in thermal management circuits. The flow channel switching inside the valve body is driven by a motor. The valve plate material must be wear-resistant and coolant-resistant, and the valve body must be pressure-resistant and sealed. The integrated runner structure greatly increases the complexity of injection molds.
In multi-way valve failure modes, plate sticking accounts for the majority, often caused by valve plate swelling or accumulation of precipitates in the runner. Controlling precipitation at the material end is more critical than wear resistance itself. This experience was gained by multi-pass valve manufacturers using after-sales data.
The expansion kettle looks simple, but the combined operation of pressure pulsation plus temperature cycling plus coolant is also quite impressive. The pressure valve seat area of the kettle cap is a weak point, where the material alternates between steam and liquid phases. Verification requires a composite test combining pressure and temperature cycling.
Extended judgment: Hidden variables in thermal management components
have three most easily missed hidden variables. First, differences in coolant formulation—different manufacturers have different corrosion inhibitor packages, which greatly affects PA and must be verified with actual coolant.
Second, scaling — prolonged high temperatures in the coolant will cause scaling, affecting the valve core and runners, requiring design for filtration or regular replacement.
Third, dry burning—after coolant leaks, the water pump runs dry, causing a sudden temperature rise. Plastic parts must have short-term dry burn resistance.
Engineering Testing: 4 mandatory tests
Test 1: Coolant soaked at 120°C for 1000 hours. Hydrolysis resistance PA66 maintains tensile strength at 80%, general PA66 drops to 48%—must withstand hydrolysis.
Test 2: Valve core wear (100,000 cycles). PPS core wear 0.05 mm, PA66 core 0.25 mm—core priority for PPS.
Test 3: Cavitation (500 hours). Surface weight loss of 8 mg for high-toughness systems, 35 mg for general systems—impeller must resist cavitation.
Test 4: Creep of quick-insert joints. PA66 relay decays by 20% after 1000 hours—design margin required.
Boundary Declaration
| Operating Condition | Recommended Materials |
|---|
| Multi-way Valve Core | PPS or PPA (Wear-resistant + Hydrolysis-resistant) |
| Valve body / pump housing | Hydrolysis-resistant PA66-GF30 |
| Pump impeller | PPS or high-toughness hydrolysis-resistant system |
| expansion kettle | PA66 semi-transparent grade |
| pipeline quick-connect connector | hydrolysis-resistant PA66-GF30 + creep margin |
engineering memo
The first barrier for thermal management components is coolant resistance — PA loses half of its strength after 1000 hours in 120℃ glycol-water solution, so a hydrolysis-resistant system is necessary. Multi-way valve cores preferably use PPS (wear is only 1/5 that of PA66).
Practical Case Study: Common Pitfalls and Correct Solutions
Pitfall 1: Choosing materials based on traditional car thinking, ignoring electrical safety requirements. Correct approach: The first criterion for plastics in new energy vehicles is often electrical performance—CTI (Comparative Tracking Index), flame retardant rating, and arc resistance. These indicators, which are not important in traditional vehicles, are strict requirements here. Pitfall 2: Only looking at flame retardant rating, ignoring long-term electrical tracking under humid heat. Correct approach: Flame retardancy reflects behavior in case of fire, while CTI reflects long-term operation—both are necessary. High-voltage parts usually require CTI ≥ 600V and flame retardant rating V-0; lacking either is a long-term risk. Pitfall 3: Simplifying the battery's working conditions as just 'high temperature', ignoring alternating hot and cold and humid heat. Correct approach: The battery pack operates in a composite environment of temperature cycling, humidity changes, and coolant; validation must include combined tests of temperature shock, humid heat, and coolant compatibility. These three pitfalls are all checklists that must be self-inspected before mass production.
Triple Follow-up Questions: Three Frequent Questions from Readers About Thermal Management Components
Question 1: What are the differences in material selection between the thermal management circuit of new energy vehicles and the cooling circuit of fuel vehicles? The temperature is higher, the flow changes more frequently, and the circuit is more complex. The coolant in fuel vehicles is around eighty degrees year-round, while the high-temperature section of new energy vehicle circuits exceeds ninety degrees, so the temperature resistance level and fatigue specifications of plastic parts are generally increased.
Question 2: Should the pump impeller use fiberglass or not? Yes, the mainstream content is 25% to 30%. The impeller needs rigidity to maintain the blade shape, and fiberglass also improves fatigue strength. But too much fiberglass makes the impeller brittle, and impacts from stones hitting the pump body need to be absorbed by toughness. The recipe is an art of balance.
Question 3: Do coolant brand and material verification need to be linked? Yes. The formulation of aftermarket universal coolants varies widely. Original equipment material verification is tied to the OEM coolant model, while universal products are tested for compatibility according to mainstream coolant brands. The compatibility database of material suppliers is the core asset of this type of project.
Reverse case: a thermostat housing sold as a universal part
An aftermarket parts factory took the drawings of an internal combustion engine thermostat housing and used them for the repair market of new energy vehicles. After being installed in cars for three months, they began to leak in batches. The root cause is that the temperature and pressure in the new energy vehicle circuits are higher, and the housing material's pressure resistance level is insufficient. Aftermarket parts are not synonymous with low quality; materials that match the operating conditions are what constitute genuine products.
Supplement: The actual problems of the other three readers
Question 4: What material is the most stable for the valve plate of a multi-way valve? It is generally agreed that a composite system with wear resistance and low precipitation is best. It is preferable to use matching grades from the same supplier for the friction pair of the valve plate and valve body, as there is a basis for the compatibility of the two sets of data. Using friction pairs across different suppliers makes it difficult to determine responsibility if problems occur.
Question 5: Which comes first, the electrical life or the mechanical life of the pump? Look at the impeller bearings. In the sliding bearing design, the mechanical life is the limiting factor, while in the rolling bearing design, the electrical life comes first. The role of impeller materials differs in the two designs: the former is more wear-resistant, and the latter focuses on strength. Confirm the bearing design before selecting the model.
Question 6: Will the thermal management integrated module replace individual parts? The trend is moving in that direction. After combining multiple valves and pumps into a single module, the number of plastic parts decreases, but the complexity of individual parts increases. The housing and flow channel components within the integrated module will be an incremental market in the coming years, and the thresholds for mold and material capabilities are rising.
A set of on-site observations
Observation one: After-sales complaints of thermal management components show seasonal patterns. Complaints during the high-temperature summer period are concentrated on pressure resistance and sealing, while complaints during the low-temperature winter period are concentrated on starting stiction. The failure mechanisms in the two seasons are different, and material selection verification needs to cover both ends.
Observation 2: Coolant compatibility is becoming a key requirement in bids. More and more OEM tender documents specify compatibility with certain brands of coolant. The more extensive a supplier's compatibility database, the faster their bid response. This kind of intangible asset is worth real money when comparing prices.
A set of closing numbers
Number one, regarding the speed limits of water pumps. The rotation speed of electronic water pump motors generally ranges from several thousand to ten thousand. The impeller's linear velocity is proportional to the rotation speed. The speed used for wear resistance testing is set one level above the highest operating speed. Each time the speed goes up one level, the material's fatigue specifications also go up one level.
Number two, regarding the upper limit of coolant temperature. The high-temperature section of the thermal management circuit for new energy vehicles is around ninety degrees, and in some high-load conditions it briefly exceeds one hundred. For every ten-degree rise in coolant temperature, the material's aging rate roughly doubles. This chemical rule determines that the temperature resistance level cannot be compromised.
Number three, regarding the level of integration of multi-way valves. The number of flow channels in mainstream multi-way valves has increased from three-way to eleven-way, with the level of integration multiplying several times. The complexity of the valve body flow channels makes injection molds a core competitive asset. In point-by-point negotiations for valve body components, mold capability is a topic on par with material capability.
The last sentence
Thermal management is the lifeline of new energy vehicles, and every plastic component in the circuit is involved in the regulation of temperature and pressure. By preparing both the coolant compatibility and fatigue life data, one can secure a position in this incremental market.
Postscript
One more point worth mentioning: the plastic parts in the thermal management circuit will retain coolant for a long time when the system is shut down. Aging from static soaking is more severe than in a flowing state, so the validation plan needs to include both static and dynamic groups; only doing the dynamic testing would be overly optimistic.
Conclusion
There are three things we never guess—when it comes to choosing materials, the earlier you ask, the less trouble it is.
The material selection and mold trial for this type of part can be discussed together.
