GB2433023A

GB2433023A - Monitoring movement of rotating arms of a cleaning machine

Info

Publication number: GB2433023A
Application number: GB0624499A
Authority: GB
Inventors: Karl Heinz Annecke
Original assignee: BHT Hygienetechnik GmbH
Current assignee: BHT Hygienetechnik GmbH
Priority date: 2005-12-12
Filing date: 2006-12-07
Publication date: 2007-06-13
Anticipated expiration: 2026-12-07
Also published as: DE102005059604B3; JP3902785B1; DK176652B1; GB2433023B; DK200601576A; JP2007160069A; GB0624499D0

Abstract

The rotational speed of cleaning arms in a cleaning machine is monitored by an electronic control circuit, if the rotational speed drops below a certain threshold, an electronic circuit returns an error message and/or switches the machine off. In the monitoring of the rotational movement of rotating arms (2, 3, 7, 8) of a cleaning machine, a desired value (nk1sn, nk2sn) for basket rotating arms (7, 8), which are attached to an insertable basket (4), is modified as a function of the measured rotational speed value (n1i,n2i) of additional permanently installed arms (2, 3). Through such a sliding desired value, influences on the rotational speed value of all rotating arms due to interfering parameters, such as fluid pressure, temperature, viscosity, and chemicals in a cleaning fluid, can be compensated.

Description

Method for monitoring a rotational movement of rotating arms of a

cleaning machine and cleaning machine for performing the method

Description

The invention relates to a method for monitoring a rotational movement of rotating arms of a cleaning machine according to the preamble of Claim 1 and also to a cleaning machine for performing the method according to the preamble of Claim 6.

A method and cleaning machine of this type are known from DE 103 47 835 Al. This known cleaning machine monitors the rotational movement of rotating arms, which are arranged on a washing basket that can be inserted into the washing space, i.e., the wet area, of the cleaning machine, by sensors, which have, for example, reed contacts and magnets allocated to the rotating arms, so that for each rotation of the rotating arm, one or two pulses are generated, which are transmitted electrically isolated via coupled coils from the wet region into a dry region of the cleaning machine and which are evaluated by an evaluation device. In this way, the output signals of several sensors can be transmitted combined as a sum signal by means of the coupled coils.

Cleaning machines, e.g., cleaning machines for medical devices, dishes, or other objects, usually have at least one rotating arm, which can be set into rotational movement by cleaning fluid emerging from nozzles of the rotating arms.

Here, sometimes clogged nozzles in the rotating arm or bulky objects can impair or even interrupt the rotational movement of the rotating arms, which degrades the cleaning result. If the machine is used for cleaning medical devices, then this is especially problematic, because greater cleanliness requirements are placed on the cleaning or rinsing result.

For this reason, the rotational movement of the rotating arm or the rotating arms is monitored by sensors. Examples here are known from DE 197 32 856 C2, DE 40 10 066 Al, DE 44 38 036 Al, DE 32 46 669 Al, DE 101 61 106 Al, and EP 0 053 231 Al.

Furthermore, in the above mentioned cleaning machine according to DE 103 47 835 Al, it is known to arrange the objects to be cleaned on a so-called cleaning basket, which can be pushed into and pulled out of a cleaning machine usually on rollers and guide rails, with at least one rotating arm being attached to the basket and this rotating arm can be connected to a supply for cleaning fluid when the cleaning basket is pushed into the cleaning machine. Such cleaning baskets are also known from DE 197 21 538 Al, DE 296 010 01, DE 296 19 272 01, or DE 38 19 275 Cl.

In practice, the rotational speeds of the rotating arms vary considerably as a function of several parameters, e.g., pressure of the cleaning fluid, viscosity of the cleaning fluid, temperature of the cleaning fluid, type of added chemicals, friction of the rotating arm bearing, amount of water in the cleaning cycle, foaming by the cleaning fluid, decrease in the output of the circulating pump, just to name a few parameters. For the monitoring of the rotational movement of the rotating arms, desired rotational speeds are preset and compared with the actual rotational speed measured by the sensors. If the absolute value of the deviation exceeds a preset threshold, then an error signal is generated and the cleaning result is rejected.

Based on the parameters that essentially influence the actual rotational speeds of the rotating arms, until to now a very wide tolerance range had to be set for the permissible rotational speeds with the consequence of an inadequate cleaning result despite rotational speeds of the rotating arms in the tolerance range.

In the monitoring of the rotational movement of the rotating arms, only the sum of the rotational speeds of several or all rotating arms on the basket is evaluated, which has the advantage that sensors and/or signal transmission devices for transmitting rotational movement signals from the basket to the dry region of the machine are eliminated; thus, it can happen that a rotating arm is partially or completely blocked and the other rotating arms rotate at a higher speed, so that then the sum signal of the rotational speeds is back within the permissible tolerance range.

In cleaning machines used today, in the interior of the machine there is typically one or two permanently or fixedly installed arms and also one or more rotating arms, which are designated below as basket cleaning arms, on the cleaning basket. Here, it has been shown that the basket rotating arms frequently assume inadequate rotational speeds, whether through poor coupling to the pressurized cleaning fluid or through blockage of the spray nozzles due to contaminants.

In practice, the desired rotational speeds of the individual rotating arms and basket rotating arms are determined in preliminary tests and programmed into a controller of the machine. Due to the parameters mentioned above, such as pressure viscosity and temperature of the cleaning fluid or type of added chemicals, the actual rotational speeds deviate considerably from the desired rotational speeds with the consequence that, on the one hand, perfect cleaning results are rejected and, on the other, erroneous cleaning results are evaluated as correct. In this sense, the cleaning result relates to the rotational speeds of the rotating arms.

With the invention, these disadvantages should be overcome. Therefore, the task of the invention is to improve a method and cleaning machine of the type named above to the extent that the monitoring of the rotational movement of the rotating arms is improved. This task is achieved by the features given in Claim 1 and Claim 6, respectively.

The basic principle of the invention lies in using the rotational speed of the permanently installed arm or arms as a reference value for the desired rotational speed of the basket rotating arm or arms. Analogously, this also applies to the summed rotational speed of several rotating arms arranged on the basket, if only its sum signal is transmitted and evaluated. Due to the parameters named above, if the permanently installed arms rotate, for example, more slowly than what corresponds to the desired rotational speed, then the desired rotational speed of the basket rotating arms or the desired value of the summed rotational speeds of the basket rotating arms can be reduced accordingly and vice versa.

Here, it can be assumed that the pressure of the cleaning fluid, which is fed to the rotating arms and which typically is delivered by a circulating pump, is within a permissible tolerance range, with this pressure preferably being measured.

The tracking of the desired rotational speeds for the basket rotating arms as a function of the rotational speeds of the permanently installed arms is obviously performed only within a predetermined tolerance range for the rotational speeds of the permanently installed arms, related to their fixed desired value of the rotational speed. Thus, it is guaranteed that for a completely or partially blocked permanently installed arm, the desired rotational speed for the basket rotating arm does not fall below a permissible value.

If the cleaning machine has, for example, two permanently installed arms with the desired rotational speeds nis and n2s, then the "modified" desired rotational speed nklsn for a first rotating arm on the basket is defined by the following formula: (nh + n2i) nkhsn = nkls. ____________ (nis + n2s) where nil and n2i are the measured actual values of the rotational speeds of the two permanently installed arms, nis and n2s are the desired rotational speeds of these rotating arms, and nkls is an originally fixed desired rotational speed of the first rotating arm on the basket.

This correction of the desired rotational speeds of the basket rotating arms has the result that the tolerance ranges for the rotating arms can be set much more narrowly for the rotating arms on the basket, which permits several rotating arms to be monitored reliably and simultaneously on the basket, whether or not one rotating arm is blocked.

The invention is explained below in more detail, by way of example, with reference to an embodiment in connection with the drawing.

The sole Figure 1 shows a schematic diagram of a cleaning machine.

The cleaning machine has a washing space 1, with an upper, permanently installed arm 2 and a lower, permanently installed arm 3, as well as a washing basket 4 (called only "basket 4" below), which can be pushed into or pulled out of the washing space 1 by means of rollers 5 on guide rails 6.

There are two basket rotating arms 7 and 8 on the basket 4.

In a known way, all of the rotating arms 2, 3, 7, and 8 have spray jets 9, from which pressurized cleaning fluid emerges, which sets the rotating arms into rotational movement. All of the rotating arms 2, 3, 7, and 8 are connected in a known way to a supply line 10, via which the pressurized cleaning fluid is fed to the rotating arms. The cleaning fluid is fed in a known way from the so-called sump 11 of the washing space 1 to a circulating pump 12 and from there under pressure via the supply line 10, in turn, to the rotating arms 2, 3, 7, and 8. Downstream of the circulating pump 12 there is a pipe branch 13 with two controllable valves 14 and 15, with the valve 14 opening or closing a connection between the circulating pump 12 and the supply line 10, while the valve opens or closes a connection between the circulating pump 12 and a drain 16, so that according to the position of these two valves, the cleaning fluid is circulated, that is, delivered from the sump 11 of the machine back to the rotating arms 2, 3, 7, and 8, or guided to the drain 16 for emptying the machine. Furthermore, the supply line 10 can be connected via a third valve 17 to a supply line 18 for cleaning fluid. In this way, cleaning or rinsing fluid or also drying air can be fed to the machine in a known way.

Although not shown in detail, it should be mentioned that the supply of cleaning fluid to the basket rotating arms 7 and 8 is realized via one or more couplings 19, which are coupled automatically when the basket 4 is pushed into the washing space 1.

It should be further mentioned that additional stationary spray nozzles can be arranged in the washing space 1 and/or on the basket 4, as is generally known in the prior art.

The machine has several sensors 20, 21, 22, and 23, which are each allocated to one of the arms 2, 3, 7, and 8 and which generate an electronic signal nh, n2i, nkli or nk2i, which corresponds to the rotational speed of the appropriate rotating arm 2, 3, 7, or 8. In principle, any type of sensor can be used, as is known, for example, from

the prior art named above.

These signals are fed to an evaluation unit 25 and evaluated there in the following way: First the signals nh and n2i, i.e., the rotational speeds of the permanently installed arms 2 and 3, are compared with fixed, preset desired values nis or n2s. If the difference between the desired value and actual value is within a predetermined first tolerance range TB1 of, for example, -50% of the desired value, then desired values nkls and nk2s for the basket rotating arms 7 and 8 are determined from the actual values nh and n2i, which is realized here according to the following relationship: nklsn = nkls. (nh + n2i) / (nis + n2s) and nk2sn = nk2s. (nil + n2i) / (nis + n2s).

If there are additional rotating arms in the basket, then the determination of their desired values is performed in an analogous way.

The new desired values nklsn and nk2sn are then compared with the actual values nkli and nk2i determined by the sensors 22 and 23. If the deviation is within predetermined second tolerance band TB2, then the rotational speeds of all rotating arms are considered to be "in order" and the cleaning process continues. In contrast, if the rotational speed of the permanently installed arms 2 and 3 is outside of the mentioned first tolerance band TB1 or if the rotational speed of the basket rotating arms 7 and 8 is outside of the second tolerance band TB2, then an error signal is generated and output on a line 26. The cleaning process can then be stopped. The error signal can have any arbitrary form. It can involve a visual or audible alarm or an "error log," which is output to a display or a printer.

Furthermore, the error signal is fed to a controller 28, which controls and monitors the program flow of the cleaning machine in a known way, for example, by controlling the circulating pump 12 and the valves 13, 14, 15, and 17, with the controller 28 also receiving from a pressure sensor 27 a signal that corresponds to the fluid pressure in the supply line 10. When receiving an error signal, the washing process can then be ended prematurely.

A possible embodiment of the evaluation circuit 25 is described below, which here is realized in hardware with logic and computing elements. It should be mentioned that obviously a programmed microcontroller can also be used, which executes the corresponding functions.

The output signal nh of the sensor 20 is fed to a first subtractor 29, where it is subtracted from a predetermined desired value nis for the rotational speed of the permanently installed upper rotating arm 2. The output signal of the subtractor 29 (nis -nh) is fed to a comparator 30, where it is compared with a fixed, preset value T81, which defines a first tolerance band for rotational movement deviations of the upper, permanently installed arm 2 from the desired value nis. If the output signal of the subtractor 29 is greater than the value TB1, then the comparator 30 switches through and thus outputs an error signal to an OR-gate 42, which then switches this signal through to the output 26 and simultaneously informs the controller 28 via a line 43. In the same way, the output signal n2i of the sensor 21 for the permanently installed lower rotating arm 3 is subtracted in a subtractor 31 from a desired value n2s and the difference compared in another comparator 32 with a fixed, predetermined value TB1, wherein, in the normal case, this value is equal to the value TB1 fed to the comparator 30. Here, when the comparator 32 switches through, an error signal is also output to the OR-gate 42. In both cases, the error signal indicates that the rotational movement of the corresponding permanently installed arm 2 or 3 is outside of the predetermined tolerance band.

For determining the desired value for the rotational speeds of the basket rotating arms 7 and 8, the desired values nis and n2s are fed to a first adder 33 and the actual values nh and n2i are fed to a second adder 34, whose output signals (nis + n2s) and (nh + n2i) are fed to a divider 35, whose output signal (nh + n2i) / (nis n2s) is fed to a first multiplier 36, where it is multiplied with a fixed, predetermined desired value nkhs and with the actual value nkhi of the sensor 22. The output signal of the multiplier 36 represents the newly modified desired value signal nklsn for basket rotating arm 7, which is subtracted in another subtractor 37 from the actual value nkli. The output signal of the subtractor 37 is fed to another comparator 38, where it is compared with a predetermined value TB2, which defines a tolerance band. If the difference between the actual value nkli and the new desired value nklsn is outside the tolerance band, then the comparator 38 switches through and outputs, in turn, an error signal to the OR-gate 42. In a corresponding way, the output signal of the divider 35 is fed to another multiplier 39, whose other inputs receive the actual value signal nk2i and a fixed, predetermined desired value nk2s for the other basket rotating arm 8. In an analogous way, another subtractor 40 and a comparator 41 are provided, which then, in turn, outputs an error signal to the OR-gate 42 when the rotational speed of the basket rotating arm 8 is outside the tolerance band TB2.

If the basket 4 has additional rotating arms, then the output signals of additional sensors allocated to these additional rotating arms are processed in the same way.

As already mentioned, the rotational speeds of several rotating arms on the basket can also be combined into one sum signal, wherein then the desired value for this sum signal is modified in an analogous way. In the present description and the enclosed claims, even if not described in detail, the term "modified desired value" can also always refer to the sum signal of the rotational speeds of several basket rotating arms and the term "rotational speed of the at least one basket rotating arm" can also refer to the actual value of the sum signal of several basket rotating arms.

From the description above, it is clear that sliding desired values for rotational speeds of the basket rotating arms are provided, which depend on the actual rotational speeds of the permanently installed arms, wherein influences from "interfering parameters," such as viscosity, temperature, pressure, and chemical composition of the cleaning fluid can be compensated for to the greatest possible extent and, as a result, much narrower tolerances for rotational movement deviations of the rotational speeds of the basket rotating arms can be set. Thus, the number of monitored basket rotating arms can also be increased.

Claims

Claims 1. Method for monitoring the rotational movement of rotating

arms of a cleaning machine, which cleaning machine has at least one permanently installed arm and at least one basket rotating arm arranged on an insertable washing basket, wherein all of the rotating arms are rotationally driven by pressurized fluid and the rotational speeds of all of the rotating arms are measured and compared with a respective desired value, characterized in that the desired value (nklsn, nk2sn) for the rotational speed of the at least one basket rotating arm is modified as a function of the actually measured rotational speed (nh, n2i) of the at least one permanently installed arm.

2. Method according to Claim 1, characterized in that the cleaning machine has two permanently installed arms and the desired value (nklsn, nk2sn) for the rotational speed of the at least one basket rotating arm is modified as a function of the rotational speeds (nil, n2i) of the two permanently installed arms.

3. Method according to Claim 2, characterized in that the desired value (nklsn, nk2sn) for the rotational speed of the at least one basket rotating arm or the desired value (nksn) for the summed rotational speeds of several basket rotating arms is modified according to the following relationship: nil + n2i nklsn = . nkl.

nis + n2s

II

with nh and n2i being the measured actual values of the rotational speeds of the two permanently installed arms, nis and n2s being fixed, predetermined desired values for the rotational speeds of the permanently installed arms, respectively, and nkl being an unmodified, fixed, predetermined desired value for the rotational speed of the at least one basket rotating arm or for the summed rotational speeds of several basket rotating arms.

4. Method according to one of Claims 1 to 3, characterized in that the desired value of the rotational speed of the at least one basket rotating arm is modified only when the measured rotational speed (nh, n2i) of the permanently installed arm or rotating arms is within a fixed, predetermined first tolerance band (TB1).

5. Method according to one of Claims 1 to 4, characterized in that an error signal is generated when the actual rotational speed (nkhi, nk2i) of the one or more basket rotating arms or a summed rotational speed of several basket rotating arms is outside of a predetermined second tolerance band (TB2) in terms of the modified desired value of the corresponding basket rotating arm or a modified desired value of the summed rotational speeds of several basket rotating arms.

6. Cleaning machine with at least one permanently installed arm, which can be set into rotational movement by pressurized cleaning fluid, with at least one basket rotating arm, which can be set into rotational movement also by pressurized cleaning fluid and which is arranged on an insertable washing basket, with sensors for sensing the rotational movement of all rotating arms, and with an evaluation circuit, which generates an error signal when the rotational speeds measured by the sensors deviate from respective desired values by more than a predetermined value, characterized in that the evaluation circuit modifies the desired value (nklsn, nk2sn) for the rotational speed of the at least one basket rotating arm as a function of the actual rotational speed (nh, n2i) of the at least one permanently installed arm.

7. Cleaning machine according to Claim 6, characterized in that it has two permanently installed arms and that the evaluation circuit is embodied so that it modifies the desired value (nklsn, nk2sn) for the rotational speed value of the at least one basket rotating arm as a function of the rotational speeds (nh, n2i) of the two permanently installed arms.

8. Cleaning machine according to Claim 7, characterized in that the evaluation circuit is embodied so that it modifies the desired value (nklsn, nk2sn) for the rotational speed of the at least one basket rotating arm according to the following relationship: nh + n2i nklsn = . nkl nis + n2s where nh and n2i are the measured actual values of the rotational speeds of the two permanently installed arms, nis and n2s are fixed, predetermined desired values for the rotational speeds of the permanently installed arms, respectively, and nkl is an unmodified, fixed, predetermined desired value for the rotational speed of the at least one basket rotating arm.

9. Cleaning machine according to one of Claims 6 to 8, characterized in that the evaluation circuit is embodied so that the desired value (nklsn, nk2sa) for the rotational speed of the at least one basket rotating arm is modified only when the measured rotational speed (nh, n2i) of the at least one permanently installed arm is within a predetermined first tolerance band (TB1) relative to a fixed, predetermined desired value (nls, n2s).

10. Cleaning machine according to one of Claims 6 to 9, characterized in that the evaluation circuit is embodied so that it generates an error signal when the measured rotational speed (nkhi, rtk2i) of the at least one basket rotating arm is outside a predetermined second tolerance band (TB2) relative to the modified desired value (nklsn, nk2sn).

11. A method for monitoring the rotational movement of rotating arms of a cleaning machine substantially as herein described and with reference to the drawings.

12. A cleaning machine substantially as herein described and with reference to the drawings.