Valve seat injector

A secondary air injection system for an internal combustion engine, the secondary air injection system comprising:

• secondary air obtaining means;
• a valve seat for a poppet valve of the internal combustion engine, wherein the poppet valve comprises a head and a stem behind the head, the valve seat comprising an aperture configured to form a seal with the head of the poppet valve when the poppet valve is in a closed position;
• and a peripheral body defining, at least in part, a plurality of ports shaped and sized to enable injection of liquid or gas from a cylinder head of the internal combustion engine into a gas stream behind the head of the poppet valve, wherein the valve seat is an exhaust valve seat, the plurality of ports shaped to provide a venturi effect to increase velocity of the gas or liquid injected into the aperture;
• and a cylinder head comprising:
• a valve seat receiving portion configured to receive the valve seat;
• and a gallery configured to inject liquid or gas to the valve seat receiving portion, wherein the cylinder head is configured to transport the secondary air between the secondary air obtaining means and the valve seat;
• wherein the secondary air obtaining means comprises a secondary air pump configured to pressurize the secondary air.

A valve seat for a poppet valve of an internal combustion engine, wherein the poppet valve comprises a head and a stem behind the head, the valve seat comprising:

• an aperture configured to form a seal with the head of the poppet valve when the poppet valve is in a closed position;
• and
• a peripheral body defining, at least in part, at least one port shaped and sized to enable injection of liquid or gas from a cylinder head of the internal combustion engine into a gas stream behind the head of the poppet valve;
• wherein the valve seat is an exhaust valve seat;
• wherein the at least one port is shaped and sized to enable injection of secondary air from the cylinder head into the gas stream;
• wherein the peripheral body defines, at least in part, a plurality of ports;
• wherein a portion of an exterior surface of the body of the valve seat facing radially away from the aperture is stepped radially inwardly to provide space for at least part of a manifold for distributing the liquid or gas to different port locations around the valve seat.