This paper focuses on the DHOS (Digital Hydraulic Operating System) injector. The injector is hydraulically actuated, electronically controlled, and employs local fuel pressure intensification. The DHOS injector utilizes a digital valve developed by Sturman Industries, Inc. The main advantages of the digital valve over a conventional solenoid include high speed, increased energy efficiency, inherent feedback, and small package size. The digital valve consists of a spool, two electromagnetic coils, and the valve housing. The spool is pulled towards the open or closed position by attractive magnetic forces produces by the open or closed coil respectively. The valve is faster than a typical solenoid primarily because it does not have to work against a mechanical spring. Furthermore, once in position, the valve requires no additional energy but instead uses residual magnetism to stay latched in position. In addition, the digital valve's two-coil design allows for the monitoring of back-EMF signals which can be used for position sensing.
In order to meet the demands of the diesel industry and emissions regulation community, injectors must be able to consistently control specific rate of injection (ROI) characteristics. The DHOS injector can electronically control the start, duration, and rate of injection of multiple injection events. The DHOS injector meets the shot-to-shot and injector-to-injector consistency required by the industry.
The primary purpose of this paper is to present the design and advantages of the digital valve. In addition, the versatility of the DHOS injector and empirical results are presented.