Timing device for fuel injector

Claim 1

An automatic hydraulic timing mechanism for a fuel injection pump on an engine comprising, a fuel injection pump including resilient means and a plunger, said resilient means including a follower spring extending to a free length and an auxiliary spring biasing said plunger to its return position, said plunger defining initially a retarded position of said plunger when said auxiliary spring is expanded and initially an advance position of said plunger when said auxiliary spring means is contracted, a fuel injection pump actuating mechanism for driving said fuel injection pump, an expansible hydraulic timing cylinder including a check valve in said mechanism for transmitting the driving force to operate said fuel injection pump, means defining a variable volume chamber in said hydraulic timing cylinder for receiving hydraulic fluid, means in said hydraulic timing cylinder defining a fully contracted position with a minimum volume position of said variable volume chamber for retarding fuel injection, said auxiliary spring in said fuel injection pump continuously pressing against said hydraulic timing cylinder throughout the fuel injecting pumping cycle and expanding while biasing said hydraulic timing cylinder to the fully contracted position when pressure of hydraulic fluid in said variable volume chamber is below a predetermined pressure with operation below intermediate engine speeds, means in said hydraulic timing cylinder defining a fully expanded position for advancing fuel injection when hydraulic fluid in said variable volume chamber at a pressure above said predetermined pressure causes said auxiliary spring to contract with operation above intermediate engine speeds, a hydraulic system including a hydraulic pump connected through said check valve to said variable volume chamber of said hydraulic timing cylinder for expanding said cylinder when pressure of hydraulic fluid is above said predetermined pressure, means connected to the said hydraulic pump adapted for driving said hydraulic pump proportional to the engine speed to thereby provide retardation of fuel injection timing at cranking speed and automatic advance of fuel injection when operating above intermediate engine speeds when the hydraulic pressure is above said predetermined pressure.