Shut-off valve for vacuum pumps

摘要

The invention relates to a shut-off valve (check valve) for oil-sealed vacuum pumps. It is accommodated in a valve housing (valve body) which is attached to the pump housing and which, by means of a fixed partition, is divided into a valve chamber, which accommodates the valve disc, the valve tappet and a pressure spring, and a swept chamber which contains the tappet, the piston and a pressure spring (compression spring). For the purpose of the passage of the tappet, the partition has a bore slide fit. The tappet is provided with a venting duct which is composed of a radial and an axial section, the latter at its front end being fitted with a nozzle. On that section of the tappet which is situated in the valve chamber, a thrust collar is permanently fixed at a distance from the partition which equals the travel. Used as the sealing element there is a seal ring bearing on the thrust collar. Next to the partition, a second oil draining hole fitted with a nozzle runs into the swept chamber. The shut-off valve does not have any dynamically stressed sealing elements. As a result, its susceptibility (proneness) to faults is low. It closes very rapidly, admitting little air, as a result of which a better vacuum is ensured.