Injection compensator for fuel injection pump

Claim 1

An injection compensating apparatus for a fuel injection pump which includes a plunger or piston, a control sleeve movably coupled over the plunger, and a tension lever rotatably about a pin in operative connection with the control sleeve comprising: a housing mounted on the pump; a pressure sensitive member dividing the interior of the housing into a first chamber and a second chamber, the first chamber being communicated to variable atmospheric and boost pressures; constant pressure maintaining means for maintaining a pressure inside the second chamber at a substantially constant reference level; the constant pressure maintaining means comprising a first check valve and a second check valve through which the second chamber is communicated to a source of vacuum supply and to the atmosphere, respectively, the first check valve opening when a pressure in the second chamber is higher than the reference level while the second check valve opening when the pressure is lower than the reference level; and a cam and follower mechanism for operative connection between the pressure sensitive member and the tension lever; whereby the pressure sensitive member controls a position of the control sleeve through the cam and follower mechanism and the tension lever in response to a pressure differential between the first and second chambers.