The usually boring world of vehicle emissions has taken center stage recently with the revelation that VW employed "defeat device" software on its vehicles to game emission compliance tests. The recent lawsuits by New York and Massachusetts bring new details to light regarding VW's software. While not discussed in the media yet, patent filings by VW may give further insight as to what was really going on inside the company.
As discussed in the NY AG's complaint, VW allegedly developed software to operate the engine in a special test mode with reduced reducing agent (e.g., ammonia) injection (the ammonia being used to reduce NOx emissions in the SCR catalyst). The reduced use of ammonia resulted in less NOx conversion, and thus significantly increased NOx emissions. It is important to note that there can be exceptions to the regulations for certain "adjustments" that would otherwise be non-compliant. Such adjustments made by the manufacturer are not allowed to reduce the effectiveness of the emission control system under conditions that may reasonably be expected to be encountered in normal vehicle operation and use unless: (1) such conditions are substantially included in the Federal emission test procedure; (2) the need for the adjustment is justified in terms of protecting the vehicle against damage or accident; or (3) the adjustment does not go beyond the requirement of engine starting.
Looking to some of VW's patents we can find at least one example of approaches that are used to adjust the amount of ammonia injection. Consider DE 102010055642, titled "a method and control device for metering a reducing agent carrier upstream of an SCR catalyst." (translated from German). The patents lists Torsten Schütte, Dr. Garbe Thomas, and Richard Dorenkamp. The NY AG's complaint specifically lists Richard Dorenkamp (former (2003-2013) and current (2013-present) head of Ultra-low Emissions Engines and Exhaust Post-Treatment within Diesel Engine Development) as involved in the scandal. The complaint asserts that he met with California regulators to provide a “technical description of future light-duty diesel emission control strategies [Lean Trap and SCR] and to discuss emission certification implications (e.g., timing).”
According to DE 102010055642, the invention purports to meter a reducing agent carrier so as to reduce the formation of deposits of the reducing agent or its decay products in the exhaust system or the metering device. The particular solution was to address the alleged wall film formation of the reducing agent carrier by reducing the dosing frequency of the reducing agent carrier at lower temperatures. According to the invention, at least the dispensing metering frequency of the reducing agent and optionally the dosing dispensing pressure of the reducing agent carrier is predetermined so that a wall film formation of the reducing agent carrier is to a large extent avoided. Allegedly, this approach was based on correlations discovered between the above dosing and the tendency to form solid deposits of the reducing agent or its decay products.
It is still to be seen whether prosecutors may use such patents as potential evidence of the alleged VW cover-up. For example, prosecutors may argue that VW was attempting to justify their reasons for reducing reductant injection at lower temperatures (off test cycle) as a form of "protecting the vehicle against damage."