DE102007026882A1 - Centrifuge i.e. solid bowl helical conveyor centrifuge, has switching device converting resonance frequency of oscillatory system during operation of centrifuge, and spring arrangement including set of springs - Google Patents

Abstract

The centrifuge has a drum rotating around an axis of rotation and includes a drive spindle rotatably supported by a storage unit with a pivot bearing. The drum and drive spindle forms an oscillatory system that is supported at a set of chassis (16) or base plate by a spring arrangement including a set of springs (18). A switching device is provided for converting a resonance frequency of the oscillatory system during operation of the centrifuge. An independent claim is also included for a method for operating a centrifuge.

Description

The The present invention relates to a centrifuge according to the preamble of claim 1.

From the EP 0 107 470 B1 and the US 4 504 262 It is known to resiliently support the drums of decanters (solid bowl centrifuges). The springs are designed as helical springs, which are aligned radially to the axis of rotation and held by bolts, which pass through the coil springs in position. As a result, in each case a resilient support between the bearing housings (or these surrounding rings or the like.) Is realized the bearing of the drum and a support ring, which is arranged concentrically to the bearing housing and attached to the machine frame or connected thereto. In this way, it should be possible to set operating speeds above the main resonance frequency of the system. Structurally may exist between the bearing housings and the surrounding support rings only a relatively small game.

The WO 94/07605 shows a similar construction as the aforementioned writings, but only one axial end of the drum is spring supported.

Around to achieve a suitable damping, it is also known the springs - which are usually made of steel - oil damper assigned.

It is also known, the drive spindles of Separatortrommeln also supported by springs. Separators are usually operated at such high operating speeds that it is necessary during startup and deceleration of the machine to the operating speed and from the operating speed down one (or more) resonant frequency (s) to go through.

In As a rule, centrifuges are tuned to the operating speed a sufficiently large distance to the main resonance speed Has.

In Practice has been found to be an appropriate vote the centrifuge needs special attention to these requirements. So requires a very "soft" vote when excited or when driving through the resonant frequency large rashes (Paths), but a low resonance frequency. A very "hard" On the other hand, voting requires excitation or passing through Resonant frequency "small" rashes, however, is the resonant frequency is high. Both variants have their advantages and disadvantages.

The Invention therefore has the task of the generic To develop the centrifuge in such a way that the problem of voting of the oscillating system is reduced. In particular, they should the disadvantages of very soft tuned systems can be avoided.

The Invention solves this problem by the subject matter of the claim 1. It also provides the method of claims 11, 12th and 13.

claim 1 provides a centrifuge with a rotatable about a rotation axis Drum, the at least one with at least one storage facility with at least one pivot bearing rotatably mounted drive spindle wherein at least the drum and preferably the drive spindle form a vibratory system, wherein the oscillatory System via a resilient arrangement on a machine frame or foundation is supported and wherein a switching device for changing the resonant frequency of the oscillatory System is provided during operation.

advantageous Embodiments of the invention are the subclaims refer to.

Preferably the spring arrangement has one or more spring (s), which at least one or more damping device (s) assigned is / are and the switching means for changing the Resonance frequency of the oscillatory system is as Switching device for changing the damping properties the at least one or more damping device (s) designed.

With the switching device, constructive in various ways is feasible, it is easily possible at the Starting and braking the machine when reaching a certain Speed the resonance speed with the damping characteristics to change and for example of harder damping properties, the were set at boot up, softer damping properties to switch when reaching the operating speed.

Conceivable For example, it is to make the switching such that the Machine initially with hard damping properties is driven to a relatively high speed, but still at not the main resonance speed for these damping characteristics was achieved. Then the damping properties changed, so the new main resonance speed for this damping properties well below the already achieved speed is.

In this way, the machine can be started up or down and decelerated accordingly, without actually passing through the main resonance speed.

moreover It is possible to reach the operating speed in desired manner relatively soft damping properties adjust. As a result, a low vibration level for reached this speed.

alternative can in a particularly simple structural design as Switching a blocking device for switching the Resonant frequency by blocking the oscillatory Systems be provided.

The Invention is suitable for centrifuges of various types, so for solid bowl centrifuges, especially with horizontal axes of rotation - and for separators with vertical axis of rotation.

following the invention is based on embodiments below Referring to the drawing explained in more detail. It shows:

1 a schematic diagram of a spring and a damping device of a centrifuge according to the invention;

2 a diagram illustrating the damping properties of a centrifuge according to the invention;

3 a schematic diagram of a first solid bowl screw centrifuge according to the invention; and

4 a schematic diagram of a second solid bowl screw centrifuge according to the invention;

5 a schematically illustrated separator;

6 a section through a drive spindle of a first separator according to the invention in the neck bearing bridge; and

7 a section through a drive spindle of a second separator according to the invention in the neck bearing bridge.

3 shows a schematic diagram of a first solid bowl screw centrifuge according to the invention with a housing 1 which is a rotatable drum 2 with horizontal axis of rotation D surrounds.

In the drum 2 is one with a differential speed to the drum 2 rotatable screw 3 arranged.

To drive here is exemplified a drive device with a gearbox with gear stages 4 . 5 , where the gear stage 4 here about belt drives 6 . 7 from a first engine 8th and a second engine 9 is driven on two shafts.

The oscillatory system of the solid bowl centrifuge, which is at least the drum 2 , the drive spindle or shaft and the worm 3 has, is by means of storage facilities 10 . 11 rotatably mounted, which at the two axial ends of the drum 2 are arranged.

As an example, here is one of the two storage facilities 10 . 11 between the two gear stages 4 . 5 axially outside the one axial end of the drum 2 and the other storage facility 11 axially outside the other axial end of the drum 2 around spindle (sections) 19 arranged.

The storage facilities 10 . 11 preferably each comprise two pivot bearings - rolling or sliding bearings 12 . 13 with bearing housings 14 . 15 - by means of springs 17 . 18 on a machine frame 16 are supported.

The rotor can at its two axial ends in each case by means of two or more of the springs 17 . 18 resilient on the machine frame 16 be supported.

The two springs 17 . 18 are here in a preferred embodiment axially - with respect to the axis of rotation D - in the region of the pivot bearing 10 . 11 arranged.

Here are the springs 17 . 18 according to the embodiment of 1 Damping devices associated, which also includes the possibility that the springs themselves may be designed as a combined spring and damping devices.

1 illustrated by means of a schematic diagram of the arrangement of the springs 17 . 18 and the damping device.

The damping device comprises a damping device 20 , the kind of a damping cylinder 21 is formed, in which a damping piston 22 slidably guided.

Above and below the piston 22 there is a fluid, for. As an oil. Moves the bearing housing 14 . 15 relative to the machine frame 16 , the fluid must be from a chamber 40 on one side or here below the piston 22 on the piston 22 past or through holes (not shown here) in the piston 22 in the other chamber 41 on the other side of the piston 22 stream. By the design of the flow cross sections gets the piston 22 more or less resistance. This results in the characteristic of the damping properties.

The damping device or the damping element 20 is above and below the damping piston 22 with a pipeline 23 . 24 connected, in each of which a valve 25 . 26 is switched, creating a further connection between the chambers 40 . 41 above and below the piston, whose cross section through the valves 25 . 26 is changeable.

By opening the change-over valve 26 The characteristic of the damping device is soft and by closing the switching valve 26 the characteristic of the damping device becomes harder. This is due to the equalizing flow between the chambers 40 . 41 of the damping cylinder 21 in combination with the piping 22 . 23 above and below the damping piston 22 reached. The cross section and the length of the pipe also influence the possible flow velocity of the equalizing flow between the chambers 40 . 41 and thus the characteristic of the damping device. The control of the changeover valve 26 can be done in particular electrically, hydraulically or pneumatically.

By further, preferably continuously adjustable valve 25 the damping behavior can be changed or adapted to the circumstances.

As in 2 can be seen, it is possible to change the damping properties during operation by switching so that when starting the machine to an operating speed R3 (deflection or path x) is first set a hard damping with a relatively high resonance frequency R2. After exceeding the speed R1 - ie a first low resonance frequency, which corresponds to a "softer" vote - and before reaching the higher resonant frequency R2 of the "harder" vote, the system is switched and the vote with the lower resonant frequency R2 turned on. The switching is thus carried out after passing through or exceeding the low resonance frequency R1, as a preferably very fast process (or abruptly). When the machine is switched off, the changeover between R2 and R1 is reversed from "soft" to "hard" after reaching a speed between R2 and R1.

so when switching on and braking the machine can switch the Resonance frequency and thus the damping properties so be made that a passing through the respective resonance speeds is avoided.

4 shows a variant of a second solid bowl screw centrifuge according to the invention, in which the storage device 10 . 11 again in each case two rotary bearings as rolling or plain bearings 12 . 13 with bearing housings 14 . 15 , which are attached to a machine frame 16 supported by springs 17 . 18 on a foundation 38 is supported.

Here are the springs 17 . 18 according to the embodiment of 4 by type 2 attenuators 20 whose function is analogous to the function of the damping elements of the embodiment of 1 is.

The invention is suitable for centrifuges of various types, such as solid bowl centrifuges, z. B. by type 3 or 4 , which generally have a horizontal axis of rotation, and for separators with a vertical axis of rotation ( 5 to 7 ). The latter are described below.

5 shows a schematic view of a separator with a rotatable drum 39 with a drive spindle 28 and a neck bearing 43 and a transmission for driving the drum. Even separators with direct drive or belt drive can be designed according to the invention.

6 shows a section through the area of a drive spindle 28 in the area of the neck bearing, the type of 5 can be designed and with the drive spindle 28 is rotatable, on which the separator drum is mounted.

The drive spindle 28 is with at least one pivot bearing 29 that has a rolling bearing ring 30 and rolling elements 44 having, wherein the ring 30 the one in a ring 42 is recorded and a spring system elastic on a machine frame 31 supported.

This support is carried out by means of at least one or more here star-shaped springs 32 as damping devices. The feathers 32 each supported against a piston 33 starting in a damping cylinder 34 is displaceable, which on the spring 32 opposite side can be acted upon with pressure (not shown here), so that the damping properties of the system can be switched during operation by the pressurization.

To limit the effect, it is conceivable a stop to limit the possible displacement of the piston 33 to provide (not shown here). Alternatively, could also be the damping cylinder 34 be configured such that the damper piston 33 directly on the ring 42 pushes when the system is set to hard.

7 shows a further embodiment, in which as a switching device for switching the resonant frequency, a blocking device 35 is provided for blocking the oscillatory system. In this case, the resonance frequency will be very high. Also, according to the invention, the resonance speed of the rotating system is switched or changed according to the invention during operation of the centrifuge when it is started up at an operating speed or during deceleration from the operating speed. The switching takes place in each case in the speed or frequency range "between" the resonance frequencies R1 and R2.

The blocking device 35 For example, with the aid of a fluid-operated cylinder, z. B. a hydraulic cylinder 36 , to be realized, which is a piston rod 37 which, in the extended position against the ring 42 press and this biases with the bearing housing. Of course, in a practical embodiment, a plurality of such cylinder arrangements could be circumferentially distributed around the drive spindle 28 or the ring 42 be arranged around (not shown here), which would then be operated synchronously.

When starting the machine, the damping device with the springs 32 simply until the resonant frequency to be exceeded is exceeded by extending the piston rods 37 against the bearing ring 30 blocked. After exceeding one or more critical main resonance frequencies, the piston rod is then withdrawn so that the damping devices are free to act and the system has the main resonance frequency R1. An analogous system can also be implemented with a decanter.

To 7 could be on the support of the springs 32 on a movable piston 33 be waived. Rather, the springs would be supported in this case on a fixed abutment (not shown here).

above The switching device was in each case by fluid-operated Cylinder realized. It is also possible to use this alternative by pneumatic, hydraulic, electromagnetic or electromotive To realize facilities (not shown here).

The Springs can also be designed as elastomer spring elements be or as the storage facility surrounding Ultrabuchse.

1

casing

2

drum

3

slug

4, 5

gear stages

6 7

belt drives

8th, 9

Engines

10 11

Storage facilities

12 13

pivot bearing

14 15

bearing housing

16

machine frame

17 18

spring elements

19

Spindle (sections)

20

attenuator

21

damping cylinder

22

damping piston

23 24

pipeline

25 26

Valve

28

drive spindle

29

pivot bearing

30

roller bearing ring

31

machine frame

32

feathers

33

piston

34

damping cylinder

35

blocking device

36

hydraulic cylinders

37

piston rod

38

foundation

39

drum

40 41

chambers

42

ring

43

Neck bearing bridge

R1, R2, R3

frequencies

D

axis of rotation

x

path

f

frequency

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0107470 B1 [0002]
• US 4504262 [0002]
• - WO 94/07605 [0003]

Claims (13)

Centrifuge with a drum rotatable about a rotation axis (D) ( 2 . 39 ), the at least one with at least one bearing device with at least one pivot bearing rotatably mounted drive spindle ( 19 . 28 ), wherein at least the drum ( 2 . 39 ) and preferably the drive spindle ( 28 ) form a vibratory system, wherein the oscillatory system via a resilient arrangement on a machine frame ( 16 . 31 ) or foundation, characterized by a switching means for varying the resonant frequency of the oscillatory system during operation. Centrifuge according to claim 1, characterized in that the resilient arrangement comprises one or more springs (s) ( 17 . 18 . 32 ), to which at least one or more damping devices (s) ( 20 ) and that the switching means for changing the resonant frequency of the oscillatory system as a switching means for varying the damping characteristics of the at least one or more damping device (s) ( 20 ) is designed. Centrifuge according to claim 2, characterized in that the damping device at least one damping cylinder ( 21 . 34 ), in which a damping piston ( 22 ) is displaceably guided and which can be acted upon by a fluid. Centrifuge according to one of the preceding claims, characterized in that above and below the damping piston ( 21 ) on the damping cylinder ( 22 . 34 ) Pipelines for the fluid are connected, in which as a switching device ( 25 ) at least one switching valve ( 25 ) is switched. Centrifuge according to one of the preceding claims, characterized in that the switching device as a blocking device ( 35 ) is designed for switching the resonant frequency by blocking the oscillatory system. Centrifuge according to claim 6, characterized in that the blocking device ( 35 ) has a fluid operated cylinder. Centrifuge according to one of the preceding claims, characterized in that the centrifuge as a solid bowl screw centrifuge, in particular with a drum ( 2 ) is formed with a horizontal axis of rotation. Centrifuge according to one of the preceding claims, characterized in that the centrifuge as a separator, in particular with a drum with a vertical axis of rotation is formed. Centrifuge according to one of the preceding claims, characterized in that the switching means pneumatic, hydraulic, electromagnetic or electric motor is designed. Centrifuge according to one of the preceding claims, characterized in that the switching device has a stop for limiting the possible displacement path of the piston ( 22 ) having. Method for operating a centrifuge after a the preceding claims, characterized in that during operation of the centrifuge when it starts up to an operating speed or when decelerating from the operating speed, the resonance speed the oscillatory system switched or changed becomes. Method for operating a centrifuge after a the preceding claims, characterized in that during operation of the centrifuge when it starts up to an operating speed the damping property of the damping device of a harder damping with a higher Resonant frequency to a softer damping with a lower Resonance frequency is switched. Method for operating a centrifuge after a the preceding claims, characterized in that in the operation of the centrifuge, a switching of the resonant frequency Blocking the oscillatory system by means of a blocking device he follows.