METHOD FOR DETERMINING THE DEGREE OF WEAR OF A VALVE, AND APPARATUS FOR CARRYING OUT SAID METHOD

Abstract

A method for determining the degree of wear of a valve, the degree of wear of the valve being dependent on the degree of wear of an operating element that is made of an expandable material and performs a mechanical movement each time the temperature changes, the change in temperature resulting in wear, the operating element made of an expandable material being mechanically connected to a piston; the movements of the operating element made of an expandable material are calculated by initially sensing the change in temperature on the operating element, whereupon the changes in temperature are recalculated as movements on the basis of the temperature/expansion curve applicable to the operating element made of an expandable material.

Claims

1. Cover for a valve for cooling circuits; comprising: an apparatus for determining the degree of wear of the valve, wherein the degree of wear of the valve depends on the degree of wear of an expandable material operating element present inside the valve, which moves a piston corresponding to a change in temperature of the expandable material operating element; wherein within the cover is housed: evaluation electronics for providing information regarding the degree of wear of the expandable material operating element; and a sensor, which, when the cover is placed on the valve, is arranged inside the valve and delivers values by means of which the degree of wear of the expandable material operating element is calculated, and the sensor is connected to the evaluation electronics, wherein the sensor, and the evaluation electronics are housed within the cover of the valve so that the sensor, and the evaluation electronics are removed with the cover when the cover is removed in a non-destructive manner for routinely replacing the expandable material operating element.

2. The cover according to claim 1, characterised in that sensors are housed inside the cover, the sensors are a temperature sensor for the temperature of the expandable material operating element (3) or for the temperature of the fluid flowing through the valve, in particular the fluid surrounding the expandable material operating element (3), and a position sensor (9) for the position of the piston (2) connected to the expandable material operating element and wherein, when the cover is placed on the valve, it can be determined from the values delivered by the sensors whether the position of the piston (2) corresponds to the position that is to be expected when the position of the piston (2) is calculated on the basis of the temperature measured by the temperature sensor and the temperature/movement curve applicable to the expandable material operating element (3) and the evaluation electronics emits a signal in the event of a deviation.

3. The cover according to claim 1, characterised in that one of the sensors is a position sensor (9), by means of which the movements of the expandable material operating element (3) or a part movable by the expandable material operating element (3) can be detected contactless or by mechanical contact.

4. The cover according to claim 1, characterised in that the signal emitted in the event of a deviation is used for the planning of maintenance work.

5. The cover according to claim 1, characterised in that two position sensors (9, 9a) are provided and a lateral play of the piston (2) in the valve (1) can be detected by evaluation of the signals delivered by the two position sensors (9, 9a).

6. The cover according to claim 2, characterised in that a measuring device is present within the cover, by means of which the temperature/movement curve for the respective expandable material operating element (3) present in the valve can be recorded, by measuring the position of the piston (2) at a plurality of temperature values and the data pairs comprising temperature and position can be stored and used for further calculations, wherein the data pairs are preferably recorded once when the change in temperature between two data pairs has a rising tendency and data pairs are again recorded when the change in temperature between two data pairs has a falling tendency.

7. The cover according to claim 1, characterised in that the evaluation electronics is connected to an optical or acoustic indicator or comprises a signal output for providing the information regarding the degree of wear of the expandable material operating element.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0037] A possible example of embodiment of the invention is explained in greater detail below with the aid of a FIGURE.

[0038] The FIGURE shows multi-way valve 1 according to the invention in a cross-sectional schematic representation.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0039] A piston 2 is arranged in multi-way valve 1, said piston being able to be moved axially by means of an expandable material operating element 3.

[0040] Multi-way valve 1 has an inlet opening 4 into which a medium can flow. Depending on the position of piston 2, the medium can flow out through one of two outlet openings 5 or 6. There are also positions of piston 2 at which the medium can flow out in part from outlet opening 5 and in part from outlet opening 6.

[0041] The expandable material operating element 3 is a wearing part and multi-way valve 1 therefore has a cover 7 by means of which the expandable material operating element 3 can be replaced. Cover 7 can be removed in a non-destructive manner.

[0042] According to the invention, a measuring device 8 with sensors 9, 9a, an indicator 10 and optionally also evaluation electronics and optionally an energy source are housed in this cover 7.

[0043] The housing of measuring device 8, position sensor 9, the temperature sensor and optionally further components in cover 7 has the advantage that an existing multi-way valve, in which the existing cover is removed for the routine replacement of the expandable material operating element, can be quickly and easily retrofitted with the invention. For the purpose of retrofitting, a new cover 7 according to the invention is fitted in place of the old cover.

[0044] Cover 7, at its outer side, optionally has an optical indicator 10, which displays the current degree of wear of the expandable material operating element 3. It is also possible to house an acoustic indicator 10 in cover 7. Indicator 10 can emit a signal when the wear limit of the expandable material operating element 3 or a threshold value still lying before the actual wear limit is exceeded. Indicator 10 is particularly advantageous in complex cooling circuits, since it can quickly be detected optically or acoustically during maintenance work whether a multi-way valve, and if so which one, requires maintenance. It is also possible for measuring device 8 to emit a signal in the event of a deviation.

[0045] Measuring device 8 can comprise, apart from position sensor 9 and the temperature sensor, further sensors, for example a second position sensor 9a or a pressure sensor.

[0046] Position sensor 9 can detect the given axial position of piston 2. As sensor principles, both contactless sensor principles are possible, for example inductive or capacitive, magnetic position measurement, optical position measurement or ultrasound position measurement. It is also possible for the position of piston 2 to be provided by mechanical coupling with a potentiometer or a variable capacitor.

[0047] In addition to the axial position determination of piston 2, it is also possible with the two position sensors 9 and 9a to detect a lateral play in piston 2. Such a lateral play in piston 2 leads, in both sensors 9 and 9a, to a quantitatively equal change in the measured value, but one that differs in respect of the sign. A lateral play in piston 2 joint with the expandable material operating element 3 is a further indication of the fact that the expandable material operating element 3 is exhibiting wear.

[0048] The temperature sensor measures the current temperature of the medium in multi-way valve 1. The temperature of the expandable material operating element 3 follows this change in temperature of the medium with a certain time-lag, which in turn leads to a movement of the expandable material operating element 3. The expandable material operating element 3 expands with a rise in temperature, whilst said expandable material operating element 3 contracts with a fall in temperature. Piston 2 connected mechanically to the expandable material operating element 3 changes its position corresponding to the change in temperature.

[0049] On the basis of a temperature/movement curve applicable to the expandable material operating element 3, the expansion and contraction of the expandable material operating element 3 can be determined solely from the permanent changes in temperature of the medium. The degree of wear of the expandable material operating element 3 can be calculated from the sum of all the expansion and contraction movements.

[0050] The temperature/movement curve applicable to the expandable material operating element 3 can be obtained from a data sheet or can be determined according to the invention by means of measuring device 8 itself. In this regard, in the case of a new valve or after the replacement of the expandable material operating element, a correlation between the temperature of the expandable material operating element and the position of piston 2 is recorded and stored for future calculations. A position is stored in respect of each discrete temperature value. A plurality of data pairs over the entire temperature range to be expected are preferably recorded and stored.

[0051] In order to take account of hysteresis effects, provision is made according to the invention to record these data pairs when the change in temperature between two data pairs has a rising tendency and again to record data pairs when the change in temperature has a falling tendency.

[0052] It can be verified by a correlation of a measured temperature value and the simultaneously measured position of piston 2 whether the expandable material operating element 3 is still expanding and contracting such as it corresponds to the temperature/movement curve applicable to the expandable material operating element.

[0053] A deviation from the temperature/movement curve is also an indication of wear. Wear can thus advantageously be detected that has actually already occurred and, what is more, before the quantitative sum of all the changes has exceeded the empirically determined value from which the signal is generated that is normally used for the planning of maintenance work.

[0054] Multi-way valve 1 or individual parts of multi-way valve 1 can also be made of a non-metallic material, for example plastic or ceramic. If, for example, piston 2 is made of a non-metallic material, a measurement method is then used which can detect the movement of a non-metallic material, for example by means of a capacitive measurement method.

[0055] In the case of a multi-way valve 1 the housing of which is made of a non-metallic material, the measuring device can be fitted externally on multi-way valve 1 and does not need to be housed in cover 7. This has the advantage that the measuring device can be retrofitted during the ongoing operation of the multi-way valve.

[0056] In the case of a multi-way valve made of a non-metallic material, it is also possible to detect by means of a suitable measuring device whether metal particles are present in the fluid or medium.