| 摘要 |
A door closer has a closer shaft 14 which is loaded in the closing direction by springs 25 via a piston 17 of a hydraulic piston cylinder damper unit. Piston head 19 is bypassed by a backflow channel 28 from a determined door opening angle, the backflow channel 28 containing a choker valve, which cushions the opening movement of a door. The piston head has a non-return valve 24 and a bypass channel 32 with a small channel cross-section. The channel is in the form of grooves 35 formed in the wall of the flow opening of the non-return valve 24, the grooves starting from the valve seat and extending into the flow opening. When the piston 17 is moving towards the closed position the non-return valve 24 is open and pressure medium can flush any dirt out of the grooves 35. The valve may comprise a spring-biased disc. <IMAGE>
|
