Combustion Engine Injection Pump for Non-Standard Fuels (Coal-Water Slurry) – Concept and Design

Diesel engines play a key role in heavy transport, but attempts to power them with non-standard fuels (e.g., coal-water slurry, CWS) encounter serious technical barriers in fuel systems. The article presents a new concept of a hypocycloidal injection pump adapted to power diesel engines with non-standard fuels such as CWS. This solution addresses the operational problems associated with the use of alternative fuels with a high content of water and solid particles, which cause, among other things, accelerated wear of fuel system components, deterioration of lubricating properties, and the need to supply larger doses of fuel due to lower calorific value. The aim of the research was to develop an injection pump capable of reliably feeding a coal-water slurry to the engine while maintaining operating parameters comparable to those of a traditional diesel fuel supply. The hypocycloidal mechanism used, replacing the classic cam, ensures linear piston movement without lateral forces. This made it possible to extend the piston stroke to approx. 40 mm (more than four times longer than in typical pumps) while maintaining the compact dimensions of the design. Thanks to the increased stroke, the pump can inject a significantly larger volume of fuel in a single cycle, which compensates for the low calorific value of CWS and allows the engine power to be maintained. The design also eliminates wear problems caused by fuel abrasiveness and low lubricity. The absence of lateral forces has enabled the use of hard ceramic coatings on the interacting components (piston and cylinder), and a separate lubrication system isolates the pump mechanism from fuel containing water and contaminants. As a result, the developed pump can provide safe and efficient engine fuel supply with non-standard fuels, reducing NOx emissions due to the presence of water in the fuel and extending the service life of the fuel system.