Patent ID: 12247556

DETAILED DESCRIPTION OF THE INVENTION

The pump device according toFIG.1has a pump piston12arranged in a longitudinally movable manner in a pump housing10, which pump piston12, controlled by an actuating solenoid device14, controls an outlet valve16to open for delivering fluid by means of fluid pressure during a delivery stroke from the right to the left as viewed in the direction ofFIG.1. When the pump piston12moves in the opposite direction from the left to the right from a forward position to a rearward position, as viewed in the direction ofFIG.1, it generates a negative pressure in a pump space18of the pump housing10during this suction stroke. If the pump piston12then passes over an annular control edge20of the pump housing10during its return motion, wherein said control edge20limits the pump space18in the direction of a fluid inlet22in the pump housing10, a fluid connection is established between this fluid inlet22in the pump housing10and the pump space18. This fluid connection is established abruptly and, due to the negative pressure in the pump space18, fluid flows from the inlet22into the pump space18at a high flow velocity, thus continuously increasing its filling volume. If the pump space18under the effect of the negative pressure present therein is filled with the filling volume, which results from a fluid flow routed along the outer circumference24from front-end parts of the pump piston12towards the outlet valve16, for further use this filling volume during the subsequent delivery stroke of the pump piston12displaced at the front end, can be discharged from the pump device via a fluid outlet26when the outlet valve16is open.

The fluid inlet22consists of a plurality of drilled holes30arranged diametrically with respect to a longitudinal axis28of the pump device, wherein the drilled holes30extend transverse with respect to the longitudinal axis28and radially through the pump housing10at the same elevation. The inner, free end of every drilled hole30opens into a circumferential radial recess32through which the pump piston12can pass and the outer diameter of which at every location being greater than the diameter of the pump space18at every location. The annular control edge20, which is formed in a continuously circumferential manner, is thus formed by a transition rim or edge, namely at the point of transition of the pump space18into the radial recess32.

AsFIG.1further shows, the outlet valve16is formed by a spring-loaded check valve, whose valve piston34, as shown in Figures land2, closes off the pump space18from the fluid outlet26when in the closed position and apart from that is arranged to extend coaxially with the pump piston12. The valve piston34is cup-shaped and accommodates parts of a return spring36designed as a compression spring in its cup space, one free end of which return spring is supported on the valve piston34and its other end is supported in a housing mount38closed at the bottom, wherein said housing mount38is preferably an integral part of a valve housing40. When the valve piston34is controlled to open against the action of the return spring36, a sealing pin42located on the free end face of the valve piston34releases an annular valve seat44on the valve housing40and fluid can be discharged from the pump space18past the valve seat44in the direction of the fluid outlet26out of the pump device. For this push-out process, a delivery stroke of the pump piston12is required, during which the piston, after passing over the control edge20, pushes the fluid in the pump space18forward and in doing so moves the spring-loaded valve piston34to its opening position away from the valve seat44. If the fluid pressure drops after the fluid volume has been discharged from the pump space18, the valve piston34can return to its shown closed position and the pump piston12moves backwards, generating a corresponding vacuum in the pump space18, until the pump piston12again passes backwards the control edge20for a new fluid filling process and takes, for instance, its rearward position shown inFIGS.1and2.

The valve seat44is formed as an annular abutment surface disposed in the valve housing40, which annular abutment surface also makes for some kind of line contact between the sealing pin42and adjacent parts of the valve housing40. As can also be seen inFIG.2, the diameter of the pump piston12is reduced in the direction of its free end face facing the valve piston34compared to its diameter in the area of the guide46of the rod-like pump piston12in the pump housing10. A recess48in the form of a diameter reduction merges seamlessly into a truncated cone50as a flow-directing device, which is adjoined by a further diameter reduction of the pump piston12having the shape of an elongated control cylinder52. The recess48forms a rectangular control edge that interacts correspondingly with the control edge20on the pump housing10to control the flow of fluid. The angle of the control cone in the form of the truncated cone50, as viewed in the direction of the longitudinal axis28, is approximately 45°, and the truncated cone, both at its base surface and at its top surface, transitions with a corresponding arc of roundness into the step-shaped recess48and into the control cylinder52, respectively, the free cross-sectional area of which is smaller than the free cross-sectional area of the pump space18in the area of the transition to housing parts of the valve housing10in the area of the valve seat44.

The pump space18has various chambers54,56and58, which are provided with different diameters and of which a central chamber56has at least in part a diameter such that an annular gap62is formed between the pump housing10and the outer diameter of the outer wall60of the pump piston12in the area of the guide in the pump housing10, which annular gap inFIG.2is depicted using a dashed line in a fictitious manner to represent the distance between the pump piston12and the pump housing10, provided that the pump piston12takes one of its forward travel positions in this respect.

As shown in particular inFIG.2, an end-face mounted annular seal64of the pump housing10is connected to the valve housing40, which receives the outlet valve16centrally as viewed in the direction of the fluid outlet26. In particular, as further shown inFIG.1, the valve housing40comprises a part of the fluid inlet22. For this purpose, further through holes66arranged diametrically to the longitudinal axis28, are arranged in the valve housing40, which through holes66are arranged at the same elevation as the holes30in the pump housing10; however, in contrast, they have a larger diameter. The valve housing40is formed like a screw-in cartridge and is accommodated in a central cuboid valve block70having a fluid inlet22transverse to the longitudinal axis28and a fluid outlet26along the longitudinal axis28by a screw-in section68. In this way, the radial recess32in the pump housing10is permanently connected to the fluid inlet22in the valve block70in a fluid-conveying manner via the drilled holes30and66.

The pump piston12is actuated by the actuating solenoid device14, which is of conventional design and has a solenoid armature74actuated by an energizable coil72and guided for longitudinal motion in a pole tube76, specifically in an armature chamber78, which has a so-called anti-adhesion disc80on its one free end face as viewed in the direction of the pump piston12. The pole tube76is secured to the valve housing40by assigned wall parts via a further screw-in section82. Further, in the attached state, the free end face of the pole tube76presses the pump housing10against the associated abutment wall of the valve housing40via the flexible annular seal64. Longitudinal channels84disposed in the solenoid armature74provide pressure-balanced operation for the solenoid armature74from its right-hand stop position shown inFIG.1, to its anterior actuation position which is anterior in the direction of the anti-adhesion disc80, and vice versa.

During actuation, i.e. when the coil72is energized, the solenoid armature74entrains a rod part86, which in turn entrains the pump piston12for one delivery stroke from its right-hand, rearward position shown inFIG.1to the left into an anterior actuation position. When the actuating solenoid14is de-energized, the pump piston12is moved to its maximum suction stroke position under the action of an energy storage in the form of the compression spring88, wherein the rod86is returned, entraining the solenoid armature74to its starting position shown inFIG.1. For this purpose, one free end of the compression spring88is supported at a free end face of the pump housing10and its other free end at a contact widening on the pump piston12. For operation without obstruction, the pole tube76has a through passage90, which connects the armature chamber78to a piston chamber92in a media-conveying manner, which as part of the pump housing10accommodates parts of the pump piston12together with the compression spring88.

The pump piston12can be actuated in temporarily close succession by controlling the actuating magnet of the solenoid device14, to ensure a quasi-continuous pump operation at the location of the fluid discharge26in the valve block70, wherein, in view of the small volume of the pump space18, only a small amount of volume is discharged at any one time. Towards the outside, the magnet device14is closed by an end plug94, which is flanged to the right free end face of the pole tube76. A screw-on nut96covers the connection between the end plug94and the pole tube76towards the outside.

The pump piston12opens the valve piston34of the check valve preferably exclusively by applying a corresponding fluid pressure, wherein the pin-like control cylinder52is used to minimize the dead volume in this area, resulting in a better efficiency of the actuation. However, it is still within the scope of the solution according to the invention to use the control pin52also for a mechanical opening operation of the valve piston34when required.