Discharge device
The invention relates to a discharge device for discharging liquid medium, with a pump device with a variable volume pump chamber, a discharge opening for the liquid medium, a feed path between the pump device and the discharge opening, and an outlet valve which is designed to open the discharge opening as a function of the pressure in the feed path, and to a discharge head provided for this purpose. The discharge device or the discharge head has a gas-permeable and liquid-tight air outlet which connects the pump chamber or the feed path to an external environment.
1. Discharge device for discharging liquid or pasty medium, comprising:
a pump device with a variable volume pump chamber limited by an input valve on an input side and an output valve on an output side,
a discharge opening for the liquid medium,
a feed path between the output side of the pump device and the discharge opening,
an outlet valve which is designed to open the discharge opening as a function of the pressure in the feed path, and
a gas-permeable and liquid-tight air outlet which connects the pump chamber or the feed path to an external environment, said air outlet being closed by a gas-permeable and liquid-tight membrane disposed to allow air located in the feed path under positive pressure to escape through said air outlet.
2. Discharge device according to claim 1 , wherein the air outlet is disposed in a region of the feed path disposed at the top of the discharge device in a use position of the discharge device.
3. Discharge device according to claim 1 , wherein the air outlet for the air and the discharge opening for the liquid extend in opposite directions from one another, the air outlet and the discharge opening being orthogonal to a main direction of extent of the discharge device.
4. Discharge device according to claim 1 , wherein the air outlet is disposed at a side of the valve slide lying opposite to a closing section of the valve slide.
5. Discharge device according to claim 1 , wherein the membrane has an average pore size of between 0.1 μm and 0.5 μm.
6. Discharge device according to claim 1 , wherein the membrane is formed integrally in a component of the discharge device.
7. Discharge device according to claim 1 , wherein the air outlet is designed to provide a microbiological seal.
8. Discharge device according to claim 1 , wherein the membrane is composed of PTFE or polyester and has a thickness of less than 500 μm.
9. Discharge device according to claim 8 , wherein the membrane has a thickness of less than 350 μm.
10. Discharge device according to claim 1 , including a suction tube connected to the pump device via the input valve on the input side.
11. Discharge device according to claim 10 , wherein the suction tube is arranged to convey a liquid or pasty medium from a media store to the pump chamber.
12. Discharge device according to claim 4 , wherein the air outlet is provided adjacent a pressure plate of the valve slide.
13. Discharge head for a discharge device, comprising:
a discharge opening for discharging liquid medium,
a feed path for transporting the medium to the discharge opening,
an outlet valve which is designed to open the discharge opening as a function of the pressure of the feed path, and
a gas-permeable and liquid-tight air outlet which connects the feed path to an external environment, said outlet being closed by a gas-permeable and liquid-tight membrane that allows air located in the feed path under positive pressure to escape through said air outlet.