Device for the volume-controlled portioning of cleaning fluid
An apparatus for volume-controlled portioning of cleaning fluid, having a housing and having a piston unit which is arranged displaceably in the housing and which displaces a cleaning fluid from a chamber into an outflow channel. In order to provide an improved apparatus, which permits exact portioning with reduced temperature dependency and in a cleaning sequence which is as quick as possible. It is proposed that the piston unit includes a piston body and at least one valve device which is arranged on the piston body and which ensures that the chamber is filled with the cleaning fluid during the reverse movement of the piston unit.
1. An apparatus for volume-controlled portioning of cleaning fluid, having a housing, having a cavity which is arranged in the housing and is able to be filled with the cleaning fluid, having at least one inflow channel which opens into the cavity and serves for feeding cleaning fluid into the cavity, having at least one outflow channel which opens into the cavity and serves for conveying cleaning fluid out of the cavity, and having a piston unit which is able to be moved in the cavity along a central axis and delimits a chamber in an actuation direction in the cavity and, from a non-actuated initial position, displaces the cleaning fluid from the chamber into the outflow channel during a forward movement in a pressure difference-actuated manner, and is moved back into the non-actuated initial position during a reverse movement, wherein the piston unit comprises a piston body and at least one valve device which is arranged on the piston body to close off the at least one inflow channel and which ensures that the chamber is filled with the cleaning fluid during the reverse movement of the piston unit, wherein the valve device has a valve body which is displaceable to a limited extent along the central axis relative to the piston body.
2. The apparatus as claimed in claim 1 , wherein the valve body has a first valve head, which has a first closure body for closing off the inflow channel, and a second valve head, which has a second closure body for closing off the outflow channel, wherein the two valve heads are coupled to one another.
3. The apparatus as claimed in claim 1 , wherein the piston unit has a spring element which preloads the valve body counter to the actuation direction.
4. The apparatus as claimed in claim 1 , wherein the piston body has at least one axial aperture, which serves for filling of the chamber with cleaning fluid.
5. The apparatus as claimed in claim 4 , wherein the valve body extends through at least one the axial aperture.
6. The apparatus as claimed in claim 4 , wherein the axial aperture is provided so as to be connected hydraulically to the chamber at all times.
7. The apparatus as claimed in claim 4 , wherein the first valve head has a sealing surface which, when the piston body abuts against the first valve head, hydraulically seals off the axial aperture.
8. The apparatus as claimed in claim 7 , wherein, there is arranged in the housing a compression spring which preloads the piston unit counter to the actuation direction and is compressed by the piston unit during forward movement.
9. The apparatus as claimed claim 1 , wherein a normally closed check valve is arranged after the outflow channel in a cleaning-fluid conveying direction and is set in an open state in a pressure difference-controlled manner when cleaning fluid is conveyed out of the chamber 3 .
10. The apparatus as claimed in claim 2 , wherein the piston unit has a spring element which preloads the valve body counter to the actuation direction.
11. The apparatus as claimed in claim 5 , wherein the at least one axial aperture is provided so as to be connected hydraulically to the chamber at all times.