Development of manifold timed water injection system
An electronically controlled system to inject water into the manifold during the intake stroke for any fixed crank angle duration was developed and installed on the engine. This consisted of a high pressure water pump which fed a solenoid operated injector. An electro-optical sensor was mounted on the cam shaft to detect the position of the piston. This sent out a pulse to trigger the water injection circuit. The electronic circuit could initiate pulses of varying width. These pulses were amplified and sent to a solenoid operated injector. The amount of water injected per cycle was controlled by varying the pulse width of the signal fed to the injector. The injector used was basically a commercially available gasoline injector. This was mounted on the manifold such that the water spray would not impinge on the walls. The injection pressure was maintained at 2 bar. This pressure was found to lead to a well atomized spray. The complete injection system is indicated in Fig. 3. The injector was mounted in the manifold in such a way that the spray of water will not impinge on the wall.