DE102021212900B3 - Method for determining an individual pressure-current working characteristic of a pressure valve - Google Patents

Abstract

The invention relates to a method for determining an individual pressure-current operating characteristic (1) of a pressure valve (2), in which at least the following steps are carried out automatically and repeatedly in succession by the pressure valve (2): a) increasing an electric drive current (3 ) for operating an actuating device (4) of the pressure valve (2),b) detecting an actual pressure value (5) of a medium (6) which is influenced by the pressure valve (2),c) storing a pressure-current value pair (3, 5) to determine the pressure-current working characteristic (1).

Description

The invention relates to a method for determining an individual pressure-current working characteristic of a pressure valve and a pressure valve for carrying out a corresponding method.

The pressure of a medium that can be set using a pressure valve depends on the position of the valve. This in turn is usually dependent on an electrical drive current of the valve. In order to record the relationships mentioned, empirical data describing these relationships are recorded during development. In the previous series, pressure-setpoint-current curves were recorded with several sample valves during development. From these an average curve was calculated. However, capturing a corresponding correction curve manually is time-consuming and can lead to inaccurate results.

This averaged correction curve was permanently programmed into the electronics of all valves in the series. This means that each valve has the same correction curve stored, regardless of the component tolerances of the respective valve. As a rule, this leads to a greater series spread, since the valves are adjusted to a specific volume flow. In addition, changing framework conditions at the customer can lead to further or larger variances.

The DE 198 06 544 A1 proposes a method for measuring an operating characteristic of an electromagnetic proportional control valve, which allows the operating characteristic to be automatically measured in a short period of time to shorten the time required for inspection upon shipment. The method is to measure a pressure/current characteristic as an operating characteristic of the electromagnetic proportional pressure control valve by gradually changing the load current with respect to the electromagnetic proportional pressure control valve one by one and measuring the pressure of the hydraulic circuit according to the load current in each step in a closed operating state of the hydraulic circuit, wherein in each step of measuring the pressure of the hydraulic circuit, the pressure is measured at a predetermined time interval. At this time, it is assumed that the pressure has stabilized at a point in time when a difference between the pressure value thus measured and the previously measured pressure value becomes a predetermined level or less, and the measured pressure value at that point in time is used as a pressure corresponding to the Load current used in this step.

Furthermore, it could be observed that the relationship between the solenoid current and the pressure that is set is not linear for controlled pressure valves. It is important to compensate for this non-linear relationship as well as possible in order to achieve the best possible pressure control. Proceeding from this, it is the object of the present invention to at least partially solve the problems described with reference to the prior art.

This object is solved with the subject matter of the independent claims. Advantageous developments are specified in the dependent claims. The features in the claims can be combined with one another in any technologically meaningful way and specify further configurations of the invention. The description, in particular in connection with the figures, explains the invention and specifies further advantageous embodiments of the invention.

1. a) Erhöhen eines elektrischen Antriebstroms zum Betrieb einer Stelleinrichtung des Druckventils,
2. b) Erfassen eines Druckistwerts eines Mediums, welches durch das Druckventil beeinflusst wird,
3. c) Speichern eines Druck-Strom-Wertepaares zum Ermitteln der Druck-Strom-Arbeitskennlinie.

A method for determining an individual pressure-current working characteristic of a pressure valve is specified, in which at least the following steps are carried out automatically and repeatedly in succession by the pressure valve:

1. a) increasing an electric drive current to operate an actuating device of the pressure valve,
2. b) detecting an actual pressure value of a medium which is influenced by the pressure valve,
3. c) storing a pressure-current value pair for determining the pressure-current operating characteristic.

In this case, it is proposed that the electric drive current be increased at a speed (gradient) that is less than or equal to a predefinable first limit speed (maximum gradient). A correspondingly slow current change and thus pressure change can advantageously contribute to the pressure current characteristic being able to be recorded as precisely as possible.

In this context, provision is also made for the electric drive current to be increased at a speed that is less than or equal to a predefinable second limit speed until a first increase in the actual pressure value is detected, with the second limit speed being less than the first limit speed. In particular, the electric drive current can be increased at a correspondingly low speed until (likewise) an increase in the actual pressure value of the medium can be detected. For example, it can be beneficial be to increase the drive current (solenoid current) only very slowly at first, especially until the actual pressure value also increases slowly. In this way, the minimum magnet current can advantageously be determined at which the pressure zero point is present (actual pressure value corresponds to the ambient pressure).

To carry out the method, steps a), b) and c) can be carried out repeatedly in the order given. In this way, in particular, different successive measuring points for determining the pressure-current working characteristic can be determined step-by-step. In this context, automated means in particular that steps a), b) and c) are carried out by the pressure valve itself, for example by a pressure valve controller (and not manually). The pressure valve can be a controlled pressure valve. For example, the pressure valve can be a pressure-reducing valve or a pressure-limiting valve.

The pressure-current working characteristic is individual. In other words, this means in particular that it is determined separately for each pressure valve (a series of pressure valves). Furthermore, the method can be carried out during the operation of the pressure valve, in particular at its intended place of use. The method can be used in a particularly advantageous manner to determine a working characteristic of pressure valves, which is done automatically for the individual valve and in particular taking into account or compensating for the non-linear relationship between the magnet current and the resulting pressure.

In step a), an electric drive current is increased to operate an actuating device of the pressure valve. The increase can be done in stages. The increase can be by a certain amount. The increase can take place at a predeterminable speed. The actuating device can be an electromagnetic and/or linear actuating device, for example comprising a magnetic coil. The increase can be initiated by a control of the pressure valve.

In step b), an actual pressure value of a medium that is influenced by the pressure valve is detected. The detection can be done by sensors, for example with a pressure sensor of the pressure valve or by means of a pressure sensor that is connected to the pressure valve. The medium can be a gas or a liquid or a mixture thereof. The medium is preferably a hydraulic fluid. By way of example, the detection can take place at each stage of the increase in the electric drive current. The pressure valve can be influenced in order to adjust the pressure of the medium, in particular a hydraulic pressure.

In step c), a pressure-current value pair is stored for determining the pressure-current operating characteristic. The storage can take place, for example, on a machine-readable memory of the pressure valve or on a machine-readable memory connected to the pressure valve. The storage can be carried out, for example, by controlling the pressure valve.

The method can describe a particularly advantageous pressure/current learning function or learning algorithm for pressure valves. Since the operating characteristic can be learned separately for each valve with the algorithm described, the series variance can advantageously be reduced. In addition, the general conditions of the customer (tank pressure and/or volume flow) can be advantageously taken into account. In particular, corresponding (predefined) desired current values can be specified in step a) to determine the characteristic and the actual pressure values can be measured in step b). By automatically measuring the pressure/current characteristic, a particularly good level of accuracy in controlled operation (pressure control) can be achieved in an advantageous manner.

The method advantageously contributes to an automatic determination of the pressure-current characteristic with advantageously constant and/or high accuracy. The comparison can advantageously be carried out in less time than would be possible manually. A pressure setpoint is usually converted into a current setpoint via the pressure/current characteristic. In this way, the non-linear relationship between the solenoid current and the pressure (in the hydraulic system) can be compensated for in an advantageous manner.

According to an advantageous embodiment, it is proposed that the method be carried out during commissioning of the pressure valve at its (intended) place of use. For example, the method for initializing the pressure valve can be carried out at its intended place of use. For example, the method may be performed prior to switching the pressure valve into an operational mode.

According to a further advantageous embodiment, it is proposed that the electrical drive current is a magnetic current. In this context, the valve can be designed as a solenoid valve, for example.

According to a further advantageous embodiment, it is proposed that the medium is a hydraulic fluid, such as hydraulic oil. In this context, the valve can be a hydraulic valve, for example.

According to a further advantageous embodiment, it is proposed that the electric drive current be increased in stages. In particular, it can be provided that after a first increase in the actual pressure value of the medium can be detected, the pressure is slowly increased in stages, with the actual pressure value and the respective solenoid current being able to be stored as a measuring point for the pressure-current characteristic at the end of each stage.

In this context, it can also be provided that between successive increases in the electrical drive current, a waiting time is observed that is greater than or equal to a predefinable (minimum) period of time. As a result, a sufficient waiting time can advantageously be observed for each current/pressure stage, so that the pressure-current characteristic can be recorded as precisely as possible.

According to a further advantageous embodiment, it is proposed that the method be carried out as needed and at the point of use of the pressure valve (possibly again). In particular, the method can be carried out (possibly again) when a customer requires it. This can advantageously contribute to the fact that the customer can also determine the characteristic again at a later point in time. It is thus advantageously possible to compensate for changes due to aging, volumetric flow or tank pressure or the like. Furthermore, the method can also be used to give the customer an advantageous option of carrying out a renewed adjustment of the entire characteristic curve if required.

According to a further aspect, a pressure valve is also specified which is set up to carry out a method described here.

Furthermore, a computer program for carrying out a method described here can also be specified. In other words, this relates in particular to a computer program (product), comprising instructions which, when the program is executed by a computer, cause the latter to execute a method described here.

A machine-readable storage medium on which the computer program is stored can also be specified. The machine-readable storage medium is usually a computer-readable data carrier.

The details, features and advantageous configurations discussed in connection with the method can accordingly also occur in the case of the pressure valve presented here, the computer program and/or the storage medium and vice versa. In this respect, full reference is made to the statements there for a more detailed characterization of the features.

• 1: einen beispielhaften Ablauf eines hier vorgestellten Verfahrens,
• 2: einen beispielhaften Aufbau eines hier beschriebenen Druckventils,
• 3: eine beispielhafte Graphik zur Veranschaulichung des hier beschriebenen Verfahrens, und
• 4: eine weitere beispielhafte Graphik zur Veranschaulichung des hier beschriebenen Verfahrens.

The solution presented here and its technical environment are explained in more detail below with reference to the figures. It should be pointed out that the invention should not be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and/or findings from other figures and/or the present description. They show schematically:

• 1 : an example of a procedure presented here,
• 2 : an exemplary structure of a pressure valve described here,
• 3 : an exemplary graphic to illustrate the method described here, and
• 4 : another exemplary graphic to illustrate the method described here.

1 shows a schematic of an exemplary sequence of a method presented here. The method is used to determine an individual pressure-current operating characteristic 1 of a pressure valve 2 (cf. 2 ). The steps a), b) and c) represented by the blocks 110, 120 and 130 can be carried out automatically and repeatedly in succession by the pressure valve 2.

In block 110, according to step a), an electric drive current 3 for operating an actuating device 4 of the pressure valve 2 is increased. In block 130, according to step c), a pressure-current value pair 3, 5 is stored for determining the pressure-current operating characteristic 1.

The method can be carried out, for example, during commissioning of the pressure valve 2 at its place of use. Alternatively or The method can be carried out cumulatively as required and at the place of use of the pressure valve 2 .

2 1 shows schematically an exemplary structure of a pressure valve 2 described here. The pressure valve 2 is set up to carry out a method described here. The pressure valve 2 can have a control device 7, for example, which can be provided and set up to carry out the method. The control device 7 can specify the drive current 3 as a function of the actual pressure value 5 and a pressure setpoint value 12 . The actual pressure value 5 of the medium 6 can be detected by a pressure sensor 9 . The medium 6 can be a hydraulic fluid, for example.

The operating characteristic 1 can be stored in the control device 7 and advantageously also recorded by the control device 7 . The working characteristic curve 1 describes the individual progression of the current 10 to the pressure 11 for the pressure valve 2 in question. The desired current value 13 can function as an input variable for a current controller 8 of the pressure valve 2 . The current controller 8 can specify the drive current 3 in this case.

The actuating device 4 of the pressure valve 2 is operated by means of the drive current 3 . The actuating device 4 can be a magnetic actuating device 4 here, for example. The electrical drive current 3 can thus be a magnetic current, for example.

3 and 4 show schematic exemplary graphics to illustrate the method described here. 3 shows in this context the course of the drive current 3 over time 14. 4 shows the course of the actual pressure value 5 that occurs and thus an example of a working characteristic curve 1 recorded according to the method.

It is in 3 to recognize that the increase in the electric drive current 3 can be carried out here at a speed (slope) that is less than or equal to a predefinable first limit speed. It can also be seen that the electric drive current 3 is increased until a first increase in the actual pressure value 5 is detected at a speed that is less than or equal to a predefinable second limit speed, the second limit speed being less than the first limit speed. It can also be seen that the electric drive current 3 can be increased in stages and that a waiting time that is greater than or equal to a predefinable time period can be observed between successive increases in the electric drive current 3 .

The method can advantageously contribute to an advantageously precise pressure being able to be set, particularly in the case of controlled operation (controlled pressure valve). Furthermore, an advantageously low linearity error can be achieved over several examples of valves.

Reference List

1

working characteristic

2

pressure valve

3

drive current

4

adjusting device

5

pressure actual value

6

medium

7

control device

8th

current regulator

9

pressure sensor

10

Electricity

11

Print

12

Index pressure value

13

current setpoint

14

Time

Claims (8)

Method for determining an individual pressure-current working characteristic (1) of a pressure valve (2), in which at least the following steps are carried out automatically and repeatedly in succession by the pressure valve (2): a) increasing an electric drive current (3) to operate a Actuating device (4) of the pressure valve (2), the electric drive current (3) being increased at a speed which is less than or equal to a predefinable first limit speed, b) detecting an actual pressure value (5) of a medium (6) which is influenced by the pressure valve (2), c) storing a pressure-current value pair (3, 5) for determining the pressure-current working characteristic (1), characterized in that increasing the electrical drive current (3) until it is detected a first increase in the actual pressure value (5) is carried out at a speed which is less than or equal to a predefined second limit speed, the z wide speed limit speed is less than the first limit speed. procedure after claim 1 , The method being carried out at its place of use during commissioning of the pressure valve (2). procedure after claim 1 or 2 , wherein the electrical drive current (3) is a magnetic current. Method according to one of the preceding claims, in which the medium (6) is a hydraulic fluid. Method according to one of the preceding claims, in which the increase in the electrical drive current (3) is carried out in stages. procedure after claim 5 , wherein between successive increases in the electrical drive current (3) a waiting time is observed, which is greater than or equal to a predefinable period of time. Method according to one of the preceding claims, wherein the method is carried out as required and at the point of use of the pressure valve (2). Pressure valve (2), set up to carry out a method according to one of the preceding claims.

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