Tappet for an internal combustion engine valve drive

Claim 1

A method of servo assisted displacement of the coupling means (10) of a tappet (1) for a valve train, which tappet (1) is installed in a bore (6) of a cylinder head (7) of an internal combustion engine and can be switched to different valve lifts for at least one gas exchange valve, said tappet (1) comprising an annular and a circular bottom section (2,3) arranged concentrically to each other and contactable each one by a cam of different lift, the tappet (1) being guided in the bore (6) by a skirt (4) connected to the annular bottom section (2), said annular and circular bottom sections (2,3) being displaceable relative to each other and adapted to be coupled to each other in the region of their common annular plane (8) by coupling means (10) which are displaceable radially by a servo medium at least in a first direction of displacement, the skirt (4) comprising at least one inlet (25) for the servo medium, which inlet (25) serves to convey the servo medium from one end (22) of a supply gallery (23) which intersects the bore (6) of the cylinder head (7) to a reservoir (15) arranged in at least one of the bottom sections (2,3) wherein a path (20) to the inlet (25) is created on or in the outer peripheral surface (5) of the skirt (4), an extent of the path (20) is such that the path (20) is in hydraulic communication with the end (22) of the supply gallery (23) during at least part of the stroke of the tappet (1), the method of displacement of the coupling means in the first direction of displacement, comprising a first step in which, prior to the first direction of displacement, the reservoir (15) is provided with a pre-pressure of servo medium during the entire time interval between a commencing valve lifting phase of the cam and a subsequent base circle phase of the cam, and a further step in which, in the subsequent base circle phase of the cam, the reservoir (15) is provided with the full, hydraulically required displacing pressure.

Claim 2

A method of servo assisted displacement of the coupling means (10) of a tappet (1) for a valve train, which tappet (1) is installed in a bore (6) of a cylinder head (7) of an internal combustion engine and can be switched to different valve lifts for at least one gas exchange valve, said tappet (1) comprising an annular and a circular bottom section (2,3) arranged concentrically to each other and contactable each one by a cam of different lift, the tappet (1) being guided in the bore (6) by a skirt (4) connected to the annular bottom section (2), said annular and circular bottom sections (2,3) being displaceable relative to each other and adapted to be coupled to each other in the region of their common annular plane (8) by coupling means (10) which are displaceable radially by a servo medium at least in a first direction of displacement, the skirt (4) comprising at least one inlet (25) for the servo medium, which inlet (25) serves to convey the servo medium from one end (22) of a supply gallery (23) which intersects the bore (6) of the cylinder head (7) to a reservoir (15) arranged in at least one of the bottom sections (2,3) wherein a path (20) to the inlet (25) is created on or in the outer peripheral surface (5) of the skirt (4), an extent of the path (20) is such that the path (20) is in hydraulic communication with the end (22) of the supply gallery (23) during at least part of the stroke of the tappet (1), the method of displacement of the coupling means in the first direction of displacement, comprising a first step in which, prior to the first direction of displacement, the reservoir (15) is provided with a pre-pressure of servo medium during the entire time interval between a commencing valve lifting phase of the cam and a subsequent base circle phase of the cam, and a further step in which, in the subsequent base circle phase of the cam, the reservoir (15) is provided with the full, hydraulically required displacing pressure.

Claim 12

A method of displacement of the coupling means (10) of a tappet (1) for a valve train, which tappet (1) is installed in a bore (6) of a cylinder head (7) of an internal combustion engine and can be switched to different valve lifts for at least one gas exchange valve, said tappet (1) comprising an annular and a circular bottom section (2,3) arranged concentrically to each other and contactable each one by a cam of different lift, the tappet (1) being guided in the bore (6) by a skirt (4) connected to the annular bottom section (2), said annular and circular bottom sections (2,3) being displaceable relative to each other and adapted to be coupled to each other in the region of their common annular plane (8) by coupling means (10) which are displaceable radially by a servo medium at least in a first direction of displacement, the skirt (4) comprising at least one inlet (25) for the servo medium, which inlet (25) serves to convey the servo medium from one end (22) of a supply gallery (23) which intersects the bore (6) of the cylinder head (7) to a reservoir (15) arranged in at least one of the bottom sections (2,3) wherein a path (20) to the inlet (25) is created on or in the outer peripheral surface (5) of the skirt (4), an extent of the path (20) is such that the path (20) is in hydraulic communication with the end (22) of the supply gallery (23) during at least part of the stroke of the tappet (1), the method of displacement of the coupling means in a further direction of displacement by a mechanical spring means (11) comprising a first step in which, prior to the further direction of displacement, the reservoir (15) is at least partly relieved of servo medium pressure during the entire time interval between a commencing valve lifting phase of the cam and a subsequent base circle phase of the cam, and a further step in which, in the subsequent base circle phase of the cam, the reservoir (15) is completely relieved of the servo pressure required for displacement.

Claim 13

A method of displacement of the coupling means (10) of a tappet (1) for a valve train, which tappet (1) is installed in a bore (6) of a cylinder head (7) of an internal combustion engine and can be switched to different valve lifts for at least one gas exchange valve, said tappet (1) comprising an annular and a circular bottom section (2,3) arranged concentrically to each other and contactable each one by a cam of different lift, the tappet (1) being guided in the bore (6) by a skirt (4) connected to the annular bottom section (2), said annular and circular bottom sections (2,3) being displaceable relative to each other and adapted to be coupled to each other in the region of their common annular plane (8) by coupling means (10) which are displaceable radially by a servo medium at least in a first direction of displacement, the skirt (4) comprising at least one inlet (25) for the servo medium, which inlet (25) serves to convey the servo medium from one end (22) of a supply gallery (23) which intersects the bore (6) of the cylinder head (7) to a reservoir (15) arranged in at least one of the bottom sections (2,3) wherein a path (20) to the inlet (25) is created on or in the outer peripheral surface (5) of the skirt (4), an extent of the path (20) is such that the path (20) is in hydraulic communication with the end (22) of the supply gallery (23) during at least part of the stroke of the tappet (1), the method of displacement of the coupling means in a further direction of displacement by a mechanical spring means (11) comprising a first step in which, prior to the further direction of displacement, the reservoir (15) is at least partly relieved of servo medium pressure during the entire time interval between a commencing valve lifting phase of the cam and a subsequent base circle phase of the cam, and a further step in which, in the subsequent base circle phase of the cam, the reservoir (15) is completely relieved of the servo pressure required for displacement.