The invention relates to a delivery device having a delivery piston displaceable in a pump chamber by means of an actuation device, which in one delivery direction removes fluid from a fluid line in a pressure-reducing manner and, in another, preferably opposite delivery direction, discharges fluid to another fluid line in a pressure-increasing manner.
Delivery devices of this type are prior art and are used in a wide variety of fields for the hydrostatic delivery of liquids. Such delivery devices, in the form of piston delivery pumps, which are actuatable by means of solenoids, are frequently used in electrically-controlled operating systems. In such applications, high demands will be placed on the operating behavior, in particular with respect to the tolerances of the delivery pressure, of the rapid response behavior with high repetition precision and with no hysteresis during periodic operation.
In view of this problem, the stated object of the invention is to provide a delivery device of the aforementioned kind, which is distinguished by a particularly favorable operating behavior.
This object is achieved according to the invention by a delivery device, which includes the features of claim 1 in its entirety.
Accordingly, a substantial distinctive feature of the invention, a valve device is introduced in each of the fluid lines allocated to the pump chamber, which valve device opens in the one delivery device during the pressure-reducing removal process and closes in the other delivery device and, in the opposite case, closes in the one delivery device and opens in the other delivery device. A high response precision and repetition precision can be achieved thereby, without hysteresis.
In preferred exemplary embodiments, the respective valve device is formed by check valves, the opening directions of which both point in a fluid delivery direction provided in the allocated fluid line.
The arrangement is obtained in a particularly advantageous manner, such that the respective fluid lines, calculated from the pump chamber to the respective check valve allocatable to said fluid line, have one and the same line segment with the same flow-through cross section. In this way, a particularly high repetition precision may be achieved without hysteresis.
The open cross section of the pump chamber in this case is advantageously the same as or smaller than the open cross section of the respectively connected line segments, relative to this connection area. Such a conformation of cross sectional sizes is advantageous with respect to repetition precision, in particular in the case of low delivery flows and high delivery pressure.
The arrangement may be obtained in a particularly advantageous manner, such that the respective fluid line is a component of a collective fluid delivery line system, into which the pump chamber with its integrated delivery piston is connected.
For high repetition precision during periodic operation and low delivery flows, the delivery piston has a needle-like extension, wherein the needle-like extension engages as a displacement element in the pump chamber, into which the free ends of the respective fluid lines open.
The actuation device is formed in a particularly advantageous manner by an energizable actuating magnet which, in its one currentless or other energized actuation state, moves the delivery piston into its pressure-reducing or pressure-increasing displaced position.
In particularly advantageous exemplary embodiments of the invention, the piston delivery pump, consisting of the delivery piston and the pump chamber, is provided with a pressure limiting device such that in the event of an undesired pressure increase in the fluid delivery line system, the pressure inside the pump chamber is limited to a predefinable maximum pressure value. The pressure limiting device integrated in the piston pump eliminates the necessity of providing other pressure limiting devices, such as pressure limiting valves. Furthermore, the disadvantages arising when attempting to limit the pressure by exploiting the lifting force characteristic of the magnetic actuation device are avoided. The resulting potential deviations in the intended electrical energy supply lead to disadvantages with respect to response precision, hysteresis and repetition precision.
To form the pressure limiting device, the delivery piston, assisted by an energy storage device, in particular in the form of a compression spring, may be advantageously movable into a resetting area which enlarges the holding volume of the pump chamber when the corresponding fluid pressure is present in the fluid delivery line system.
In particularly advantageous exemplary embodiments, an arrangement is advantageously obtained in this case, in which another energy storage device, in particular in the form of another compression spring, permanently acts on the delivery piston, which compression spring seeks to move the delivery piston into a delivery area that reduces the volume of the pump chamber. In this way, the pressure limiting is independent of the energy supply of the actuating magnet, and instead, is defined according to the characteristic of the two compression springs engaging the delivery piston.
The invention is explained in detail below with reference to an exemplary embodiment depicted in the drawings, in which:
In
The free end of the actuating plunger 21 abuts a pressure body 23, on which one end of a compression spring 25 is supported, the other end of which abuts an actuating part 26 of the pump delivery piston 27, the actuating part 26 of which is axially displaceable in the bore 5. The end of the delivery piston 27 facing away from the actuating part 26 includes a needle-like extension 29, which engages as the actual displacement part of the delivery piston 27 in a pump chamber 31, which is formed in the housing 1 as a continuation, severely reduced in diameter, of the bore 5. Another compression spring 33, which surrounds the delivery piston 27 between the actuating part 26 and the step 28 formed in the bore 5 at the transition to the pump chamber 31, is inserted between this step 28 and the actuating part 26.
As indicated merely symbolically in
Number | Date | Country | Kind |
---|---|---|---|
10 2013 016 030.8 | Sep 2013 | DE | national |
Filing Document | Filing Date | Country | Kind |
---|---|---|---|
PCT/EP2014/002380 | 9/3/2014 | WO | 00 |