Patent Suit Asserts Duramax Engines Under Kruse Control


Kruse Technology Partnership (“Kruse”) is an Anaheim, California partnership that owns several U.S. patents relating to its higher efficiency and cleaner burning diesel engines.

Last month Kruse filed its First Amended Complaint against DMAX, Ltd. (“DMAX”), an Ohio diesel engine manaufacturer formed as a joint venture between GM and Isuzu. 

The amended complaint (kruse_amended_complaint.pdf) alleges that DMAX’s Duramax engines infringe three related Kruse patents:  U.S. Patent Nos. 5,265,562 (“‘562 patent”), 6,058,904 (“‘904 patent”) and 6,405,704 (“‘704 patent”).

The asserted patents are entitled “Internal combustion engine with limited temperature cycle” and are directed to Kruse’s “Limited Temperature Cycle” technology, which limits peak combustion temperatures in direct injection gas and diesel engines. 

The Limited Temperature Cycle injects fuel in multiple increments both before and after ignition.  According to Kruse’s web site, such injection of partial quantities of fuel reduces the combustion temperature, boosts thermal efficiency and reduces certain chemical emissions.

The asserted patents claim this process and describe an engine incorporating the invention.  The engine (10) comprises a block (12), a cylinder head (14) and a cylinder (16) having a piston (18). 

Fuel is supplied to the engine (10) by a fuel injection system (36).  The engine (10) also includes an air induction system (26) having an air intake valve (28) in the cylinder head (14).


One key feature of the process is the maintainance of a proper fuel/air mix in the engine to reduce the temperature and the work of compression.  According to the ‘904 patent, the fuel injection system (36) precisely regulates this fuel/air mixture for combustion and exhaust emission control.

The complaint requests that the court issue a permanent injunction against DMAX and award Kruse compensatory damages for the alleged infringement.

Eric Lane Avatar

Eric Lane

Eric Lane, the founder and principal of Green Patent Law, is an intellectual property lawyer and registered U.S. patent attorney in New York and is a member of the bar in New York and California. Eric has more than two decades of experience working with wind, solar PV, CSP, biofuels, and geothermal, energy storage technologies, carbon capture and sequestration, medical devices, data communications, mechanical, chemical, internet and software.