Internal combustion engines

Claim 2

An internal combustion engine having at least one cylinder containing a reciprocable piston, an inlet passage for air or air/fuel mixture leading to the engine cylinder, means to ignite the air/fuel mixture, a branch passage leading from the inlet passage to the ignition means to deliver air or air/fuel mixture thereto, and a single valve for opening and closing both the inlet and branch passages, the valve having a first position for closing both said inlet and branch passages, a second position for opening said branch passage and closing said inlet passage, and a third position for opening both said branch and inlet passages.

Claim 3

An engine as claimed in claim 1 further comprising a carburetor and wherein said inlet passage is connected to said carburetor to supply air/fuel mixture to said inlet passage.

Claim 4

An engine as claimed in claim 1 wherein means are provided for injecting fuel into the inlet passage.

Claim 5

An engine as claimed in claim 2 further comprising a pre-combustion chamber and wherein said carburetor is arranged to supply an initial part of the charge of mixture which is fuel rich for each engine cycle so that the mixture supplied to said pre-combustion chamber is fuel rich and to supply the subsequent part of the mixture which is a weak mixture direct to said engine cylinder.

Claim 6

An engine as claimed in claim 1 wherein the valve controlling the inlet and branch passages is a poppet valve and an annular seat is formed in the inlet passage adjacent the cylinder to receive the head of the valve to close the passage, said branch passage extending from the wall of the inlet passage between said seat and the end of the inlet passage at the cylinder, the branch passage being located opposite the periphery of the valve head when the valve is closed so as to be closed by the valve head.

Claim 7

An engine as claimed in claim 1 wherein a pre-combustion chamber is provided in communication with the engine cylinder and said branch passage is arranged to deliver air or air/fuel mixture to the pre-combustion chamber.

Claim 8

An engine as claimed in claim 6 wherein the pre-combustion chamber is located at the end of the cylinder, the branch passage being connected direct to the pre-combustion chamber, the ignition means for igniting the air/fuel mixture being provided in the pre-combustion chamber and the chamber having an outlet orifice to the engine cylinder.

Claim 9

An engine as claimed in claim 7 wherein the piston crown is formed with a recess extending opposite the valve and the pre-combustion chamber in the cylinder head to receive air/fuel or burning mixture from the pre-combustion chamber and air from the inlet passage and the recess in the piston receiving the valve in the open position thereof when the piston approaches the top of its stroke.

Claim 10

An engine as claimed in claim 6 wherein the pre-combustion chamber comprises a recess formed in the outer face of the crown of the piston reciprocating in the cylinder.

Claim 11

An engine as claimed in claim 1 wherein said engine cylinder includes a cylinder head with an inlet port, and said inlet passage terminates in said inlet port, said single valve is a poppet valve, said branch passage comprises a slot formed in said cylinder head extending from one side of said inlet port to a location adjacent said ignition means, the end of said slot being closed by said poppet valve in said first position thereof and being opened to said inlet passage in said second position on initial opening movement of said poppet valve to feed air/fuel mixture to said ignition means, full opening of said poppet valve in said third position opening said inlet passage to feed air or air/fuel mixture to said cylinder.

Claim 12

An engine as claimed in claim 10 wherein said cylinder head further includes an annular insert formed at the outlet end of said inlet passage, said annular insert includes an annular seat around the inner periphery thereof to receive said poppet valve in said first position thereof, and said slot extends through said annular seat to said inlet passage within said annular seat.

Claim 13

An engine as claimed in claim 10 wherein the slot has a smoothly curved bottom wall which converges towards the surface of the cylinder head over the pre-combustion chamber to direct air or air/fuel mixture into said chamber.