SIL 4车轮滑动保护系统:神话还是现实?

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在铁路运输中, wheel slide protection systems (WSP) manage the delicate wheel-to-rail adhesion issue. In dry situations, the adhesion between the steel wheel 和 the steel rail is already low by nature. This available adhesion represents the physical limit of the train’s braking performance. 外部因素，如下雨, 冰, 落叶, pollution or contamination with oil or grease can further reduce available adhesion. 出于这个原因, 轨道制动器供应商, 多年来, 开发车轮滑轨保护系统. These systems monitor the rotation speed of the four axles of the vehicle in real time, calculating average vehicle speed 和 axle rotational speed variation. 每次系统检测到轴滑动, the wheel slide protection adjusts the pressure in the corresponding brake cylinder(s) to ensure the axle doesn’t lock, 避免轮胎漏气的风险, 火车运行中潜在的安全问题. The system ensures that each axle will use available adhesion to generate braking force.

在上面的场景中, there is a risk that one or more axles can remain in a brake released status if there are any failures in the wheel slide protection control or if adhesion is very low. 显然，松开刹车是不安全的. That’s why all wheel slide protection systems include an independent watchdog (WD) function that reapplies full brake effort if the brake release comm和ed by the wheel slide protection is longer than a set time (often 10 seconds). 最终, it means that applying the brake 和 risking full axle slide is preferred to no braking at all.

This watchdog function is key to ensuring the safety in traditional wheel slide protection systems. The watchdog is an independent hardware dev冰 that leaves the WSP function deactivated once it has been triggered.

在现实中, the first generation of WSP systems avoided axle slide by fully releasing brake effort when slide was detected. The drawback of this type of system was a dramatic braking distance increase in degraded adhesion.

The second generation of WSP systems (introduced in the ‘90s) is capable of fully managing the slide of each axle, 使可用附着力得到最佳利用. 多亏了这个, 在降低附着力的制动距离大大减少, 为提高列车运行安全性做出贡献.

仍然, some of the operators would like to see higher safety level for wheel slide protection system especially when used in Emergency brake.

当我们开发出集成制动控制系统时 Metroflexx & Regioflexx 家庭方面，我们采用双电子架构. One Safety Integrity Level 2 (SIL 2) unit performs the usual Brake Control Unit (BCU) function, 和 one SIL 4 unit – with SIL 4 hardware 和 software – performs monitoring 和 redundancy functions. This specific electronic architecture has created new opportunities to reinforce the safety of the wheel slide protection system:

• A SIL 4 monitoring function that continuously monitors the wheel slide protection by checking the behaviour of each axle (speed, 减速, 等.) 和 manages brake effort to obtain optimal 减速 with available adhesion in real time.
• 一个完全SIL 4认证的看门狗功能. 传统的看门狗功能仍然有效, 但WSP监控通过快速阻止其激活, 高精度控制. WSP monitoring therefore significantly reduces the risk of axle lock/wheel flat in very low adhesion conditions, 提高列车安全性和可用性.
• An integrated SIL4 wheel rotation monitoring (WRM) function for very high-speed application is available, enabling massive system simplification for both the car builder (initial cost) 和 the operator (maintenance cost).

The market reaction to the reinforced safety 和 performance of wheel slide protection  systems has been so positive that we have decided to offer the same technology on traditional braking systems, 采用单独的bcu和气动. 我们开发了SIL 4 明智的™ board to be integrated into our traditional Gemini II brake control unit (BCU). 明智的™ 是完全独立的, dedicated SIL 4 hardware 和 software solution that uses its own power supply.

当配备明智的时™, your train can use wheel slide protection when emergency braking without any safety concern, 多亏了它的sil4看门狗功能. The SIL 4 wheel slide protection monitoring function can make your train much more resilient in very low adhesion conditions. 除了, maintenance cost can be greatly reduced due to better energy management at wheel/rail contact point energy.

So, back to the initial question about SIL 4 wheel slide protection: myth or reality? It will certainly remain a myth for most market players for the time being. 但为了瓦布泰克和我们的智者™ 电子产品, it’s already a reality, with proven design 和 benefits.

Looking for more information on SIL 4 wheel slide protection systems 和 明智的™ 电子产品? 联络我们: brakes和couplers [at] wabtec (点) com