DE10249558A1 - Radial piston pump has annular spring in form of polygon progression fitted between slide rings and with length of broken flank shorter than length of each unbroken flank - Google Patents

Abstract

The radial piston pump comprises cylinder bores (1) housing pistons (3) arranged in star-form around an eccentric (12). Between the pistons and drive shaft (11) are fitted at least two slide rings (14,15) between which a spring (16) in the form of a polygon progression is fitted. The length of a broken flank of the annular spring is shorter than the length of the unbroken flank and is in the region of 40 to 80 per cent of it. The annular spring is designed so that the spring rating is kept constant over the whole circumference.

Description

The invention relates to a radial piston pump with several in one pump housing provided cylinder bores for the inclusion of spring-loaded pistons that form a star shape an eccentric are arranged. On the eccentric are for smooth The piston is provided with two sliding rings, between which a ring spring for damping of pressure peaks in the radial direction is provided. The pressure rooms of the Pistons are above exhaust valves in connection with a consumer.

Radial piston pumps the advantage of their working principle that the flow rate from an average speed of, for example, 1,600 rpm through the Intake throttling is limited. Above this speed the Piston interior is no longer completely filled. This means that the start of delivery from the filling dependent after the piston has closed its associated suction opening. At the Funding begins the piston therefore with speed dependent Speed on the enclosed oil column and pushes the oil over designed as a circumferential band spring Check valve, that closes all outlet bores of the pistons in one with the consumer connected collecting channel. Because the piston is not moving at speed Start promoting zero there is a strong pressure surge in the Piston interior. The one generated by such a surge Pressure peak exceeds the outlet pressure in the collecting channel many times over. The pressure surges increase with the principle increasing speed. The pressure surges of all Pistons rain a structure-borne noise at who about the housing wall is emitted as airborne sound.

A radial piston pump of this type built into a gearbox is already from the DE 43 36 673 C2 known.

An embodiment shown there this ring spring has the shape of a regular polygon and can Radial pressure surges Take direction. The flank lengths the ring spring are above that the entire circumference is the same and therefore also the angular distance at which the flanks are distributed. The ring spring is interrupted on one flank, since it is advantageously made of tape material and it is also easier to assemble. This is called that Closed the Feather.

Ring springs of this type take radial pressure surges Towards. The pistons of the pump are supported on the eccentric springy, so that they can deflect at the beginning of the extension. On in this way, the pressure peaks can be reduced, which occur on impact the piston emerge on the oil column

The spring rate is strong due to the lock reduced, the spring rate is over the circumference is distributed unevenly. (The spring rate describes the increase in spring force per mm of spring travel). In addition, the interrupted Flank adjacent corners at very high voltages. These two Properties to a reduced noise and surge absorption through the Ring spring. Due to the uneven voltage and spring rate distribution is the component only with loss of the desired functional properties can be dimensioned permanently.

The basis of the invention The task is to develop a radial piston pump at which the noise and pressure surges can be further reduced.

The basis of the invention Task is performed by a radial piston pump with the characteristics of Main claim solved.

The main feature of the new pump is in that the damping element installed between the two sliding rings consists of a ring spring in the form of an irregular polygon, and that the flank length the interrupted edge is less than that of the other edges. Thereby is achieved that the service life as well as the component function the ring spring can be significantly improved.

The ring spring according to the invention alternately touches with their inside or outside corresponding to the inner or outer slide ring. More specifically contacts the ring spring at its outer corners with the outer slide ring and on the inside of the flanks with the inner slide ring. Essential for the solution according to the invention is that the flank lengths of the polyline is unevenly long accomplished especially the length the interrupted edge is less than that of the other edges. This means that the corners of the polygon are also at an uneven angular distance above the Scope distributed.

This ring spring is advantageous open on one side executed so that they are easy to manufacture on the one hand from tape material and on the other hand is easy to assemble.

The functional properties of the ring spring are directly related to their width and sheet thickness d. In front all through the sheet thickness the spring rate and the life of the ring spring is strongly influenced. In the castle area leads the Interruption of a flank, which is viewed as a classic bending beam can become extremely high Tensions at the two neighboring corners. Furthermore, the spring rate in the castle area smaller than on the continuous flanks. This leads to the circumference of the spring an uneven damping of the Noise- and pressure peaks. Due to the uneven tension and spring rate distribution the previously known interrupted ring springs only at a loss the desired one functional properties can be dimensioned permanently.

The invention is based on the following of the embodiments shown in the drawing.

Show it:

1 a partial cross section through a radial piston pump with a cushioning of the piston by a slotted ring spring;

2 a schematic diagram of the ring spring with inner and outer ring and

3 a schematic diagram of the calculation model of the ring spring.

The pump after 1 points in cylinder bores 1 a pump housing 2 a number of pistons 3 on. Every piston 3 is by a spring 4 loaded on one of the cylinder bore 1 sealing plug 5 supported.

A ribbon spring 6 spans all plugs in a ring-like manner 5 and closes to interiors 7 subsequent outlet bores 8th against a collecting ring groove 10 , The band spring 6 is with pens 9 on the pump housing 2 secured in their position. A drive shaft 11 carries an eccentric 12 on which a sliding bush 13 is arranged. According to the invention is between one on the sliding bush 13 slipped inner slide ring 14 and a concentric outer slide ring 15 a ring spring as a damping element 16 built-in. When rotating the eccentric 12 can the piston pushing out the pressure oil 3 on the associated section of the slide ring 15 deflect slightly so that the pressure peaks occurring at the beginning of a pressure stroke can be reduced. The band spring 6 bulges from its seat over each piston 3 who is currently performing a pressure stroke. The pistons 3 suck the pressure oil at its top edge through suction openings 17 on.

The ring spring according to the invention 16 consists of a polygonal polygon between two sliding rings 14 . 15 is arranged. The outer ring 15 touches the outside 23 the corners 18 , the inner ring 14 the inside 22 the flanks 19 . 20 the ring spring 16 , This creates a situation similar to that of a classic bending beam, in which a radial or external force F acts from outside or inside.

In the ring spring according to the invention 16 the geometry was changed so that both the service life and the component function could be decisively improved. For this, the sheet thickness 26 , the angular distance α, β, the lever arms 24 . 25 and the bending stress σ_1, σ_2 in a mathematical relationship to each other. By specifying optimization goals, the best possible or any other ratio of spring rate to service life can be determined. Optimization goals can include: B. a 'uniform spring rate over the circumference' or 'bending stress small limit'.

Through the optimization, the bending stress σ_1 of the lock 21 neighboring corners 18 drastically reduced. This can be done by shortening the lever arm 24 can be achieved while reducing the angular distance β. This also increases the life of the ring spring 16 , The spring rate is kept constant over the entire circumference, which results in a significant reduction in noise. Due to the drastic reduction in tension, the sheet cross-section of the spring 16 can also be reduced, thereby reducing the spring travel of the ring spring 16 is significantly increased, which brings with it a further significant reduction in noise.

The flank length 24 the interrupted edge is compared to the edge length of the continuous edge 25 in an advantageous embodiment of the ring spring according to the invention in the range from 10% to 90%, particularly advantageously in the range from 40% to 80% of the length of the continuous flank 25 ,

1

cylinder bores

2

pump housing

3

piston

4

feather

5

Plug

6

band spring

7

inside rooms

8th

outlet bores

9

pencils

10

Sammelringnut

11

drive shaft

12

eccentric

13

bush

14

internal sliding ring

15

outer slide ring

16

Ringfeder

17

suction ports

18

corner

19

interrupted flank

20

through flank

21

Lock

22

inside

23

outside

24

Flank length in the lock area

25

Flank length without Lock

26

Sheet thickness ring spring

α

angular distance the corners of a closed flank

β

angular distance the corners of the broken flank

σ_1

bending stress at the corners of the broken flank

σ_2

bending stress at the corners of the continuous flanks

F

thrust

Claims (6)

Radial piston pump with the following features: - in a pump housing ( 2 ) are several cylinder bores ( 1 ) for receiving pistons ( 3 ) provided in a star shape around an eccentric ( 12 ) are arranged; - on the eccentric ( 12 ) are for the frictionless drive of the pistons ( 3 ) Sliding elements stored; - interior of the pistons ( 3 ) are connected to a consumer via outlet valves; - between the pistons ( 3 ) and a driving wave ( 11 ) are at least two slide rings ( 14 . 15 ), between which in turn a spring ( 16 ) is installed in the form of a polygon, which is on one of its flanks ( 19 ) is interrupted and which with the outside ( 23 ) their corners ( 18 ) on the outer slide ring ( 15 ) and with the inside ( 22 ) the flanks ( 18 ) on the inner slide ring ( 14 ) and thus enables a spring force in the radial direction, characterized in that the ring spring ( 16 ) has the shape of a polyline, the flank length ( 24 ) the interrupted flank ( 19 ) the ring spring ( 16 ) is shorter than the flank lengths ( 25 ) of the uninterrupted flanks ( 20 ). Radial piston pump according to claim 1, characterized in that the length of the interrupted flank ( 24 ) in the range of 40 to 80% of the flank length ( 25 ) of the continuous flank 20 lies. Radial piston pump according to claim 1, characterized in that the ring spring ( 16 ) is designed so that the spring rate of the ring spring ( 16 ) is kept constant over the entire circumference. Radial piston pump according to claim 1, characterized in that the annular spring is designed so that the bending stresses (σ_1, σ_2) in the corners ( 18 ) the ring spring ( 16 ) are below a limit. Radial piston pump according to one of the above claims, characterized in that the ring spring ( 16 ) eight flanks ( 19 . 20 ) has. Radial piston pump according to one of the above claims, characterized in that the ring spring ( 16 ) is made from tape material.