EFFECTS OF BOUNDARY CONDITIONS ON A BOSCH-TYPE INJECTION RATE METER

Sandor Vass,Máté Zöldy

doi:10.3846/transport.2021.14351

Sandor Vass, Máté Zöldy

Open Access

https://doi.org/10.3846/transport.2021.14351

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Abstract

Spread and evolution of Common Rail (CR) injection systems enable to influence injection events more efficiently than ever, while injection mass flow rate during an injection event crucially affects the combustion process. A measurement device based on the work of Bosch was set up, and measurements were made with different boundary conditions to explore the capabilities of the measurement system and to validate a detailed model of a CR injector. The main finding of this research work is, that orifice size had no noticeable effect on the measured injection rate traces, while it was stated in the original work that a small orifice is needed to terminate the measuring tube to maintain stable measurement conditions. Moreover, the backpressure level in the measuring system has a significant effect on the measured injection traces. If pressure in the measuring tube is low, gradient at the injection rate rise is lower, while if the pressure is comparable with that of a combustion chamber maximal compression pressure, measurement of higher doses is unaccomplishable due to the long pressure decrease time in the measuring tube after the end of the injection. Based on the results of the investigation, it can be stated that the Bosch-type injection rate measurement method does not give back the exact injection rate shape, a supplementing method would be necessary to calculate real nozzle flow rate.

Highlights

Modern diesel fuel injection systems used in road vehicles have to fulfill stringent requirements owing to the newer and stricter worldwide emission standards (Zöldy 2019)
A measurement device based on the work of Bosch was set up, and measurements were made with different boundary conditions to explore the capabilities of the measurement system and to validate a detailed model of a Common Rail (CR) injector
The main finding of this research work is, that orifice size had no noticeable effect on the measured injection rate traces, while it was stated in the original work that a small orifice is needed to terminate the measuring tube to maintain stable measurement conditions

Summary

Introduction

Modern diesel fuel injection systems used in road vehicles have to fulfill stringent requirements owing to the newer and stricter worldwide emission standards (Zöldy 2019). Engines are designed to treat average diesel fuel according to the standards (Zöldy 2020). Fuel injection during one engine cycle is split into 2...7 parts to maintain the desired burn rate and through this engine performance and raw emission (Hiwase et al 2013; Agarwal et al 2013). Effects of boundary conditions on a Bosch-type injection rate meter timing, pressure and length (Jurić et al 2019) could only be achieved with the appearance of CR injection systems, which separate pressure generation from fuel metering (Stumpp, Ricco 1996)

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