EP2278161A2 - Piston pump with multiple pistons - Google Patents

Abstract

The pump (1) has a set of pistons (6, 7) driven by an eccentric cam (4), where the eccentric cam exerts a compressive force on the pistons. The pistons are connected with each other by a single-piece u-shaped bent pin element i.e. clip (8), that absorbs tractive forces in the operation of the piston pump. The pistons execute a reciprocating movement by the eccentric cam, where the pistons are displaceable to a starting position during the movement by the pin element. The pin element is connected with each piston by a detachable plug connection.

Description

State of the art

Devices for conveying fluids, ie gases or liquids, e.g. Pumps with a plurality of pistons or piston pumps, in which the pistons are moved in a piston chamber, are known in various designs.

For example, the pistons can perform a repetitive reciprocating motion via a rotatable or rotatable eccentric. With in particular exactly one eccentric two or more pistons can be moved. By acting on a contact surface on a piston, the eccentric can move it away from a starting position or push it away into a position that is moved away from the initial position. The pressure force is applied in particular to the piston over the entire duration of a reciprocating motion. Subsequently, the piston moves under a reversal of the direction of movement back to the starting position before it is pushed away again by reversing the direction of movement of the eccentric again. The eccentric exerts only a compressive force on the piston. As a rule, the phases of movement of the two or more pistons are out of phase with each other. With two pistons, the forward movement of one piston advantageously runs simultaneously with the reciprocation of the other piston and vice versa.

Purpose and advantages of the invention

Object of the present invention is to improve a piston pump of the aforementioned type with regard to technical and economic aspects, in particular more reliable, easier or more compact to realize.

This object is achieved by claim 1.

In the dependent claims advantageous developments of the invention are defined.

The invention relates to a piston pump with a plurality of pistons, which are driven by an eccentric, the eccentric exerts only a compressive force on the piston. The essence of the invention is that the pistons are connected to one another via an element which can absorb at least tensile forces during operation of the piston pump. This makes it possible to implement a corresponding piston pump in a particularly simple and space-saving manner.

Thus, a reliable return movement is realized particularly advantageous after a movement of the piston by pushing it away by means of the eccentric. A piston, which performs a reciprocating movement in a continuously repeatable movement cycle opposite to the forward movement, can undergo a restoring action via the element. The element sets up the return of a piston during the cycle of movement. This also takes place continuously repeated, wherein the piston can be brought over the element in particular in a starting position at the end of the reciprocating movement.

In particular, previously provided measures or return means with which a return movement of the piston was made, replaceable by a comparatively much simpler and more compact design solution.

So far, for example, coil spring means are used as return means, which act permanently on the piston under bias. This spring force, which also increases upon compression of the coil spring, must overcome and exceed the eccentric in pushing away the piston to allow the desired movement of the piston. After elimination of the action of pressure of the eccentric on the piston, the appropriately tensioned in the forward movement spring can cause the return of the piston. A momentary strong impact on the piston, so that it is urged into a stop position, may be disadvantageous in terms of wear and disturbing noises.

In addition, it is disadvantageous that this arrangement means extra work for construction and assembly and also on parts. In addition, mechanical springs, especially under varying loads in their spring function with time or can tire, possibly jam and / or tilt, so that the pump can fail.

It is further proposed that two pistons are provided, which perform a reciprocating motion via the eccentric, wherein the at least two pistons are displaceable in the movement over the element into a starting position. Thus, after a maximum possible forward movement of a piston this can be retracted by the element back to the starting position.

It is particularly advantageous that the element is connected via a releasable connection with a piston. Thus, the arrangement and in particular the element can be very easily assembled and disassembled.

It is further proposed that the element is connected via a plug connection with a piston. A particular tool-free set up and releasable connector allows for quick and easy assembly and disassembly of the corresponding element.

Preferably, the element is designed substantially as a rigid component. Thus, the element can be realized very stable.

In particular, the element is advantageously designed in one piece. This also facilitates the assembly and disassembly of the piston pump.

It is further advantageous that the releasable plug connection is designed such that the element in a direction transverse to the direction of movement of a piston in the piston can be inserted. Thus, it is possible to prevent forces acting on the element during the movement of the piston from acting in the insertion direction of the element. This eliminates the risk of unwanted loosening of the connector.

Preferably, the element is designed as a pin member having a bent end portion which is inserted in the installed state in a matched to the end portion receiving opening. This makes the element easy and inexpensive to deploy.

It is particularly advantageous that exactly two pistons are provided, which are connected via a common U-shaped element. Thus, a coupling of the two pistons can be achieved particularly advantageous. In particular, it is advantageous if the two pistons are aligned with their longitudinal axes and the eccentric sits between them. The directions of movement of the pistons, ie the reciprocating motion, also coincides with the longitudinal orientation of the pistons. The element can bridge the area occupied by the eccentric and couple the pistons together. In this case, the element can be used parallel to the longitudinal direction of the piston, so to speak, in the extension thereof.

figure description

With reference to an embodiment of a piston pump according to the invention shown in the figures further features and advantages of the invention will be explained.

Figur 1

einen Längsschnitt durch eine erfindungsgemäße Kolbenpumpe unter Weglassung einzelner Teile z.B. einer Gehäuseabdeckung und

Figur 2

einen Schnitt durch die erfindungsgemäße Kolbenpumpe gemäß Linie A - A in Figur 1, wobei eine in Figur 1 nicht dargestellte Gehäuseseite in Figur 2 nicht weggelassen ist.

In detail shows:

FIG. 1

a longitudinal section through a piston pump according to the invention omitting individual parts such as a housing cover and

FIG. 2

a section through the piston pump according to the invention according to line A - A in FIG. 1 , where one in FIG. 1 not shown housing side in FIG. 2 not omitted.

A piston pump 1 according to the invention has, for example, an electric motor 2 as a drive unit, with which an eccentric 4 can be driven in rotation by means of a transmission designed here as a planetary gear 3. The eccentric 4 has a deep groove ball bearing 5 on the outside, so that the eccentric 4 is formed on the outside by a circumferential outside of an outer race 5a of the deep groove ball bearing 5, which is non-rotatably connected to an associated inner race 5b which is non-rotatably connected to the rotatably drivable inner part 4a of the eccentric 4. can perform a relative movement. Thus, relative movements or friction between the outer side of the outer race 5a and an inner end face 6a or an inner end face 7a of two oppositely positioned cylindrical pistons 6 and 7 avoided or at least reduced to a significant extent, when the eccentric 4 the respective Pushes piston 6 or 7 away. The pushing away of the pistons 6, 7 takes place due to the changing with the rotation of the eccentric 4 effective radius of the respective outer portion of the outer race 5a, wherein the respective outer portion with the respective end face 6a and 7a is in contact while pressure forces the end face 6a and 7a exerts. In this case, only one piston 6 or 7 is always pushed away or transmitted to one of the end faces 6a, 7a compressive forces. The other piston 6 and 7, in contrast, motion-coupled again used to the eccentric 4, which is explained below.

As described, with the rotation of the eccentric 4, the pistons 6, 7 are moved outwards or away from the eccentric 4. This movement of the pistons 6, 7 to the outside is indicated by the arrow P1 for the piston 6 and by the arrow P2 for the piston 7. In accordance with FIG. 1 shown position, the piston 7 is pressed over the eccentric 4 outward according to arrow P2. On the other hand, the piston 6 is applied by the eccentric 4 just no pressure force or its end face 6a is only touching on the outside of the outer race 5a on.

In order to achieve a provision of the outwardly pressed over the eccentric 4 pistons 6, 7 in a more inward position, so after movement according to the arrows P1 and P2 an opposite direction to allow movement of the pistons 6, 7, is a return element , which is designed here as a bracket 8, is provided. If the eccentric 4 according to FIG. 1 continues to turn, the piston 7 according to arrow P2 after he has moved to a maximum position to be reached, which is set on the maximum value of the outer radius of the eccentric 4, then pulled back in the opposite direction to P2, ie according to arrow P1, inward , This is done via the bracket 8.

The clip 8 is formed here as a U-shaped bent metal pin, the clip 8 is inserted with its ends bent ends 8a and 8b in corresponding openings 9, 10 or through holes in the piston 6 and in the piston 7. The bent end portion 8 a is in the opening 9 in the piston 6 and the bent end portion 8 b is inserted into an opening 10 in the piston 7. With this connection between the pistons 6 and 7, the respective piston, after a maximum movement outward according to the arrows P1 and P2 by the action of the eccentric 4 on the other piston, which is pushed away to the outside, attracted back to the eccentric 4. When moving outward, the pistons 6, 7 acted upon by compressive forces and the subsequent moving inward, the pistons 6, 7 brought by tensile forces back into a starting position or in a most retracted position.

As a result of the reciprocating movement of the two pistons 6, 7, a fluid, for example a hydraulic fluid of a hydraulic unit, can be conveyed in a known manner. Here, the hydraulic fluid is conveyed, for example, in a pressure-side outgoing line on the movement of the piston 6, 7.

In FIG. 1 For example, a hydraulic connection 11 for the connection of a hydraulic fluid line (not shown) is shown.

LIST OF REFERENCE NUMBERS

1

piston pump

2

electric motor

3

planetary gear

4

eccentric

4a

inner part

5

Deep groove ball bearings

5a

Outer race

5b

Inner race

6

piston

6a

front

7

piston

7a

front

8th

clip

8a

end

8b

end

9

opening

10

opening

11

hydraulic connection

Claims (9)

Piston pump (1) with a plurality of pistons (6,7), which are driven by an eccentric (4), wherein the eccentric (4) on the piston (6, 7) only exerts a compressive force, characterized in that the piston (6 , 7) are connected to one another via an element (8), which can absorb at least tensile forces during operation of the piston pump (1). Piston pump according to claim 1, characterized in that two pistons (6, 7) are provided which perform a reciprocating movement via the eccentric (4), wherein the at least two pistons (6, 7) move through the element (8) are displaceable to a starting position. Piston pump according to claim 1 or 2, characterized in that the element (8) via a releasable connection to a piston (6, 7) is connected. Piston pump according to one of the preceding claims, characterized in that the element (8) is connected via a releasable plug connection with a piston. Piston pump according to one of the preceding claims, characterized in that the element (8) is designed substantially as a rigid component. Piston pump according to one of the preceding claims, characterized in that the element (8) is designed in one piece Piston pump according to one of the preceding claims, characterized in that the releasable plug connection is designed such that the element (8) in a direction transverse to the direction of movement of a piston (6, 7) in the piston (6, 7) can be inserted. Piston pump according to one of the preceding claims, characterized in that the element (8) is designed as a pin element which has a bent end portion (8a, 8b) which in the installed state in a on the end portion (8a, 8b) tuned receiving opening (9 , 10) is inserted. Piston pump according to one of the preceding claims, characterized in that exactly two pistons (6, 7) are provided, which are connected via a common bow-shaped element (8).

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