Camshaft control device and control valve with leakage compensation
View Patent ↗The invention concerns a control device for adjusting the relative angular position of a driven shaft, particularly a camshaft of an internal combustion engine, said device comprising a drive pinion that is rotatably connected to the shaft, an adjusting element ( 1 ) for the angular adjustment of the drive pinion relative to the shaft, two chambers ( 2, 3 ) that are alternately supplied with hydraulic fluid and a control valve ( 6 ) for actuating the adjusting element ( 1 ), said control valve being connected to the chambers ( 2, 3 ) of the adjusting element ( 1 ) through pressure medium channels ( 4, 5 ). The control valve ( 6 ) comprises a valve body ( 7 ) that has two working connections A and B for the pressure medium channels ( 4, 5 ), a delivery connection P for the supply of hydraulic fluid and a discharge connection T for the discharge of hydraulic fluid, and the control valve ( 6 ) further comprises a sliding valve control piston ( 8 ) for setting different hydraulic resistances W between the individual connections. In an intermediate adjusted position of the valve control piston ( 8 ), for setting an intermediate phase angle, a lower hydraulic resistance W prevails between the delivery connection P and that one of the working connections A and B at which a design-related, higher fluid leakage V occurs.
1. A control device for adjusting a relative angular position of a driven shaft, particularly a camshaft of an internal combustion engine, with the following features:
the control device comprises a drive pinion that is rotatably connected to the shaft,
the control device comprises an adjusting element ( 1 ) for the angular adjustment of the drive pinion relative to the shaft, and further comprises chambers ( 2 , 3 ) that are alternately supplied with hydraulic fluid,
the control device further comprises a control valve ( 6 ) for actuating the adjusting element ( 1 ), said control valve being connected to the chambers ( 2 , 3 ) of the adjusting element ( 1 ) through pressure medium channels ( 4 , 5 ),
the control valve ( 6 ) comprises a valve body ( 7 ) comprising working connections A and B for the pressure medium channels ( 4 , 5 ), a delivery connection P for the supply of hydraulic fluid and a discharge connection T for the discharge of hydraulic fluid,
the control valve ( 6 ) further comprises a sliding valve control piston ( 8 ) for setting different hydraulic resistances W between the individual connections,
in a first adjusted position of the valve control piston ( 8 ), the connections between the connections P and A and between the connections B and T have a low resistance W and the connections between the connections P and B and between the connections A and T have a high resistance W,
in a second adjusted position of the valve ( 8 ), the connections between the connections P and B and between the connections A and T have a low resistance W and the connections between the connections P and A and between the connections B and T have a high resistance W,
in a third adjusted position of the valve control ( 8 ), the connections between the connections A and T and between the connections B and T and the connections between the connections P and A and between the connections P and B have a high resistance W,
wherein in the third adjusted position,
either to compensate for fluid leakage V from the pressure medium channel ( 4 ) at the connection A, control regions ( 17 , 17 ′) of the valve control piston ( 8 ) have different circumferentially extending radii R so that, the resistance W between connections P and A is lower than the resistance W between P and B,
or to compensate for fluid leakage V from the pressure medium channel ( 5 ) at the connection B, control regions ( 17 , 17 ′) of the valve control piston ( 8 ) have different circumferentially extending radii R so that, the resistance W between the connections P and B is lower than the resistance W between P and A.