Hydraulic traction mechanism tensioners having a generic design are already known from the prior art. One example of a design is disclosed in DE 10 2004 012 394 A1, a hydraulic tensioner for a traction means, in particular for a chain or a belt, being prepared and having a damping action which is varied via the lift. In this connection, the damping action increases as the lift also increases.
Another hydraulic tensioning device is the subject matter of DE 602 00 696 T2. A tensioner housing, including a tensioning piston, is shown, which together enclose a high pressure chamber. The high pressure chamber is connected to a hydraulic medium supply. In addition, the hydraulic chamber is connected to a relief valve to avoid an excessive pressure in the high pressure chamber. The relief valve includes a valve element receiving bore, which is connected to an oil supply opening, as well as a valve element which is situated to be displaceable forwardly and backwardly in the valve element receiving bore. The relief valve furthermore includes a spring, which pretensions the valve element in the direction of the oil supply opening, and an oil relief opening in a surrounding wall of the valve element receiving opening. The oil relief opening is situated at a point where it is closed when the valve element moves backward due to a rapid increase in the oil pressure at the oil supply opening, whereby a quantity of oil is trapped in the valve element receiving opening to damp the movement of the valve element.
US 2015/0 024 887 A1 shows a tensioning device for a chain drive, including a housing, a tensioning piston and a high pressure chamber enclosed by the housing and tensioning piston. The high pressure chamber is connected to a supply port via a check valve and an inlet line. A spring-loaded pressure regulating piston, which closes the inlet opening if a pressure rises in the inlet line, is situated in the inlet line.
Another tensioning device is the subject matter of DE 10 2010 034 485 A1. The illustrated tensioning device includes a housing and a tensioning piston, which together enclose a high pressure chamber supplied with hydraulic medium via an inlet line. A check valve unit essentially prevents the hydraulic medium present in the high pressure chamber from flowing out in the direction of the inlet but permits a limited outflow against the inlet direction via a leakage gap between the housing and the check valve unit.
In traction mechanism tensioners of this type, however, it has been shown in certain operating states that a relatively great friction may be frequently generated by a relatively high tensioning force of the particular tensioning piston on the traction mechanism. Moreover, the activation of a traction mechanism tensioner of this type is often relatively complicated for the purpose of setting the corresponding damping force of the tensioner or reducing the contact force.
USPTO Backgrounds
USPTO Backgrounds