Hydraulic camshaft adjuster and method for operating the same

Abstract

A hydraulic camshaft adjuster for adjusting the angle of rotation of the camshaft of an internal combustion engine relative to its crankshaft, including an external rotor connected in a rotationally fixed manner to a driving wheel, and an internal rotor connected in a rotationally fixed manner to a driving wheel, and an internal rotor connected in a rotationally fixed manner to a camshaft, the external rotor having at least one hydraulic chamber with radial partitions and two side walls, and the internal rotor having a hub with at least one hydraulically swiveling blade which divides the hydraulic chamber into two working chambers operated by oil pressure which is controlled by an electronic regulator via a control valve. The swiveling blade having, between stops, a base position which can be locked by pins in grooves.

1 . A hydraulic camshaft adjuster for adjusting the angle of rotation of the camshaft of an internal combustion engine relative to its crankshaft, said camshaft adjuster having an external rotor ( 1 ) connected in a rotationally fixed manner to a driving wheel, and an internal rotor ( 2 ) connected in a rotationally fixed manner to the camshaft, the external rotor ( 1 ) having at least one hydraulic chamber ( 8 ) with radial partitions ( 3 ) and two side walls ( 10 ,  11 ), and the internal rotor ( 2 ) having a hub ( 5 ) with at least one swiveling blade ( 7 ) which divides the hydraulic chamber ( 4 ) into two working chambers ( 8 ,  9 ) in an oil-tight manner, it being possible for each swiveling blade ( 7 ) to be swiveled hydraulically between a trailing stop ( 19 ) and a leading stop ( 18 ) by an oil pressure which is controlled by an electronic regulator via a control valve, and each swiveling blade having, between the stops ( 18 ,  19 ), a base or central position which can be locked by two spring-loaded and hydraulically unlockable locking pins ( 20 ,  21 ), wherein the locking pins ( 20 ,  21 ) are preferably of identical design and are arranged in the hub ( 5 ) of the internal rotor ( 2 ) and parallel to its rotational axis ( 12 ) and can be latched into preferably identically designed locking grooves ( 25 ,  26 ) in at least one side wall ( 10 ,  11 ):  
     
     
         2 . The camshaft adjuster as claimed in  claim 1 , wherein the locking grooves ( 25 ,  26 ), which are designed in the shape of a circular arc, of the locking pins ( 20 ,  21 ) are arranged on a preferably common circle about the rotational axis ( 12 ) of the external and internal rotors ( 1 ,  2 ).  
     
     
         3 . The camshaft adjuster as claimed in  claim 2 , wherein the locking grooves ( 24 ,  26 ) have preferably semicircular ends ( 27 ,  27 ′ and  28 ,  28 ′) and are designed to be of a width which corresponds to the diameter of the locking pins ( 20 ,  21 ), which diameter is enlarged by a clearance to allow movement.  
     
     
         4 . The camshaft adjuster as claimed in  claim 3 , wherein one of the ends ( 27 ,  27 ′ and  28 ,  28 ′) of the two locking grooves ( 25 ,  26 ) is designed in each case as a central stop ( 29 ,  30 ) for the locking pins ( 20 ,  21 ), for fixing the central position of the swiveling blades ( 7 ).  
     
     
         5 . The camshaft adjuster as claimed in  claim 4 , wherein the central stops ( 29 ,  30 ) are arranged mirror-symmetrically, so that a different swiveling direction of the internal rotor ( 2 ) is blocked by each central stop ( 29 ,  30 ).  
     
     
         6 . The camshaft adjuster as claimed in  claim 5 , wherein the ends ( 27 ,  27 ′ and  28 ,  28 ′) of the two locking grooves ( 25 ,  26 ) are arranged, when the swiveling blades ( 7 ) bear against the leading stop or against the trailing stop ( 18 ,  19 ), at a distance from the locking pins ( 20 ,  21 ) which are each latched in place.  
     
     
         7 . The camshaft adjuster as claimed in  claim 6 , wherein the central stops ( 29 ,  30 ) can be set with respect to the leading and trailing stops ( 18 ,  19 ) by rotation of the first side wall ( 10 ), which is provided with the locking grooves ( 25 ,  26 ), relative to the external rotor ( 1 ).  
     
     
         8 . The camshaft adjuster as claimed in  claim 7 , wherein the locking grooves ( 25 ,  26 ) and their oil channels ( 31 ,  32 ) are flow-connected to the corresponding working chambers ( 8 ,  9 ) via oil lines ( 33 ,  34 ) which are preferably arranged in the first side wall ( 10 ).  
     
     
         9 . The camshaft adjuster as claimed in  claim 1 , wherein the locking grooves ( 25 ,  26 ) are in each case arranged separately in the two side walls ( 10 ,  11 ).  
     
     
         10 . A method for operating a hydraulic camshaft adjuster according to the preamble of  claim 1 , wherein the electrical regulator regulates the oil pressure in the working chambers ( 8 ,  9 ) during the shutting off and restarting of the internal combustion engine in such a way that, with the additional use of the dragging torque of the camshaft, the starting of the engine takes place from a base or central position of the swiveling blades ( 4 ), which position is locked by the two locking pins ( 20 ,  21 ).  
     
     
         11 . The method as claimed in  claim 10 , wherein at low idling of the internal combustion engine before it is shut off, the electrical regulator charges, via the control valve, the first working chamber ( 8 ) together with associated first locking groove ( 25 ) with oil pressure, as a result of which the first locking pin ( 20 ) is unlocked and the swiveling blades ( 7 ) come to bear against the leading stop ( 18 ) while the second locking pin ( 21 ), with the second working chamber ( 9 ) unpressurized, is situated outside the second locking groove ( 26 ) and is prestressed by its compression spring ( 23 ).  
     
     
         12 . The method as claimed in  claim 11 , wherein, with the internal combustion engine at a standstill and, as a result, an absence of oil pressure, the first locking pin ( 20 ) is latched in the first locking groove ( 25 ) and the swiveling blades ( 7 ) have a swiveling position between the leading stop ( 18 ) and the base position while the second locking pin ( 21 ) is also arranged outside the second locking groove ( 26 ) and is prestressed by its compression spring ( 23 ).  
     
     
         13 . The method as claimed in  claim 12 , wherein, when the internal combustion engine is started, the internal rotor ( 2 ) is adjusted to “trailing” by the dragging torque of the camshaft until the first locking pin ( 20 ) in the first locking groove ( 25 ) comes against the first central stop ( 29 ) and thereby-enables the second locking pin ( 21 ) to latch into the second central stop ( 30 ) of the second locking groove ( 26 ), so that the starting of the engine takes place with the central position completely locked.  
     
     
         14 . The method as claimed in  claim 13 , wherein, directly after starting of the engine has taken place, the regulator raises the oil pressure in the first oil pressure lines ( 14 ), the first working chambers ( 8 ) and the first locking groove ( 25 ), thereby unlocking the first locking pin ( 20 ) and keeping the second locking pin ( 21 ) in pressure contact with the second central stop ( 30 ).  
     
     
         15 . The method as claimed in  claim 14 , wherein, in order to transfer to regulated operation, the regulator adjusts the swiveling blades ( 7 ) into the region before the trailing stop ( 19 ), by means of a higher pressure in the second working chamber ( 9 ) than in the first working chamber ( 8 ), and thereby also unlocks the second locking pin ( 21 ), so that the internal rotor ( 2 ) can move freely.