Injection pumps for internal-combustion engines

An injection unit for an internal-combustion engine comprising a rotary feed pump having a delivery duct connected to an injection pump (11) a centrifugal governor (15) being provided to regulate the unitary rate of delivery of the injection pump (11), a rotary member (16) being also provided, rotating concurrently with the rotary feed pump and on which centrifugal masses (18) are linkably mounted which are displaced by the action of centrifugal forces to displace, against the bias of resilient means (21) creating forces acting in a first direction, a member axially in a second direction opposite the first direction (19) for regulating the rate of delivery of said injection pump, characterized by said rotary member (16) of the governor (15) having a surface opposing an abutment surface of an axial supporting member (20, 30, 43) and defining therewith a chamber (35), said chamber (35) communicating with the delivery duct of the rotary feed pump iva a conduit (33) throttled by a restricted section (34), the pressure of the liquid contained in said chamber (35) acting in a direction opposite said first direction against and to counteract the axial bias of said resilient means and said centrifugal masses (18) of said centrifugal governor to establish pressure values which are increased as the rpm of the governor is increased, and means (40) responsive to the pressure values and connected to said chamber (35) to deliver a signal which is a function of said rpm.