A novel combustion chamber valve and fuel system for driven fastener hand tool is disclosed having a fuel pump disposed parallel to the combustion and piston chambers. Pressure applied a safety at the nose of the tool is activates the fuel pump in a common direction. Pressure applied on a trigger activates the valve system prior to firing in a common direction. The valve system employs a central shaft coupling three valves, an inlet valve using a novel wedged circumferential edge seal, a control valve using a novel edge circumferential seal with a ventilated support, and a charging exhaust valve using a face seal.

An internal combustion engine for a vehicle is provided, having at least one cylinder with a first gas exchange inlet valve, a second gas exchange inlet valve, a first gas exchange outlet valve, a second gas exchange outlet valve, and a piston with a piston crown which has a plurality of valve seat pockets. In each case one valve seat pocket is provided for the first gas exchange inlet valve, the second gas exchange inlet valve, the first gas exchange outlet valve and the second gas exchange outlet valve, and the plurality of valve seat pockets have at least partially different depths. Alternatively, one valve seat pocket is provided for the first gas exchange inlet valve and the first gas exchange outlet valve, and no valve seat pocket is provided for the second gas exchange inlet valve and/or for the second gas exchange outlet valve.

A novel combustion chamber valve and fuel system for driven fastener hand tool is disclosed having a fuel pump disposed parallel to the combustion and piston chambers. Pressure applied a safety at the nose of the tool is activates the fuel pump in a common direction. Pressure applied on a trigger activates the valve system prior to firing in a common direction. The valve system employs a central shaft coupling three valves, an inlet valve using a novel wedged circumferential edge seal, a control valve using a novel edge circumferential seal with a ventilated support, and a charging exaust valve using a face seal.

An internal combustion engine for a vehicle is provided, having at least one cylinder with a first gas exchange inlet valve, a second gas exchange inlet valve, a first gas exchange outlet valve, a second gas exchange outlet valve, and a piston with a piston crown which has a plurality of valve seat pockets. In each case one valve seat pocket is provided for the first gas exchange inlet valve, the second gas exchange inlet valve, the first gas exchange outlet valve and the second gas exchange outlet valve, and the plurality of valve seat pockets have at least partially different depths. Alternatively, one valve seat pocket is provided for the first gas exchange inlet valve and the first gas exchange outlet valve, and no valve seat pocket is provided for the second gas exchange inlet valve and/or for the second gas exchange outlet valve.

Disclosed is a control device for an engine provided with a first intake valve and a second intake valve in an intake port. The control device comprises: a variable valve operating mechanism (72) configured to control a valve opening timing and a valve closing timing of an intake valve (21a); and a variable valve operating mechanism (72) configured to control a valve opening timing and a valve closing timing of an intake valve (21b), independently of the intake valve (21a). The latter variable valve mechanisms (72) is operable, in an intake stroke of the engine, to close the intake valve (21b) after the elapse of a delay time rt since the intake valve (21a) is closed. The delay time rt is a time period during which a pressure wave generated upon closing of the intake valve (21a) reaches the intake valve (21b) through the intake port (16).