| 摘要 |
The invention relates to a device for applying material such as pastes and glues in discrete points. The device comprises a pump house (208) having a pumping chamber (206) located therein. Material is fed to the pumping chamber (206) from a tube (202) and there is a nozzle (215) for feeding material out from the pump house (208). Furthermore, there is an upper valve housing (203) which can block the material flow into the pumping chamber (206), and generally a lower valve housing (212) or similar device, which can block the material flow from the pumping chamber (206) to the nozzle (215). The pump house is realized by a piezo-electric material having electrodes (209 and 210) connected to a drive voltage generator. By choosing and orienting the piezo-electric material in a suitable way it can be achieved that the volume of the inner cavity of said pump house (208) depends of the voltage, which is applied between the electrodes (209, 210). This change of volume can be used for pressing out the material in a pumping stroke, when the valves inside the valve housings (203, 212) are set in a suitable way. The valve elements (204, 213) inside the valve housings (203, 214), can comprise thin bands, which are provided with holes (205, 214), these valve elements being separately controlled or commonly driven, e.g. as a part of a band which completes a full turn. |
