Patent Page

Hvid Engine Combustion


| December 2005



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Americans saw a record high price of $70.85 per barrel of crude oil on Aug. 30 of this year, and since then, large truck and SUV sales have plummeted and hybrid car sales have soared. As of the end of September 2005, 154,563 hybrid vehicles were sold in the U.S., as compared to just 88,000 in the entire 2004 calendar year, an increase of over 175 percent.

Without a doubt, the quest for better fuel economy is stronger now than ever before. However, this quest began many years ago.

In 1915, Rasmus Hvid, inventor of the Hvid engine, sought to improve the fuel economy of stationary engines by creating an engine that would run on heavier, low-grade (i.e., cheaper) fuels such as kerosene, as opposed to gasoline or Diesel.

This invention, patented April 6, 1915, is what Hvid (pronounced "Veed") called an "Oil Injection Device for Oil Engines." It essentially worked on the principles of Rudolf Diesel's engine, but with a twist: The Hvid relied solely on the heating and compression of air to ignite the fuel, without the use of compressors, pumps, injectors, etc., to aid combustion.

The beauty of the Hvid engine lies in its simplicity, making it easier to produce, and thus, easier on the pocketbook. And although this engine was designed to run on low-grade fuels, according to a 1937 Hvid Diesel service manual, "… they will also run on any other standard grade of Diesel fuel thin enough to flow through the fuel pipes, whether it is distillate, fuel oil, crude oil, or any other similar oil."

How it Works

In a typical 4-stroke configuration, as all Hvid-type engines are, we can look at Figure 1 and assume the piston (B) is at top dead center, having just completed the exhaust stroke, and that the exhaust valve is closed. As the piston moves towards the bottom of the cylinder (A) on the intake stroke, the intake valve (C, Figure 2) opens and air is allowed to enter the cylinder throughout the stroke. While this is occurring, the fuel inlet valve (10) simultaneously opens to let oil enter the cup (3).