DE102016221435A1 - Warning device for a fluid container and method for testing the same - Google Patents

Abstract

The invention relates to a warning device (1) for monitoring an event in a container (3) with a fluid (2) comprising a movable position sensor (4) whose position depends on the level of the fluid (2) in the container (3) and a signal unit (5) which, depending on the position of the position sensor (4), undergoes at least one state change which is detected as an electrical signal and methods for functional testing of the warning device (1) .To propose an improved warning device (1), the functionality of which can be checked as reliably as possible even in the case of rarely occurring events is proposed according to the invention in that the warning device (1) is designed to actively initiate the change of state of a signal unit (5) integrated therein independently of the event to be monitored.

Description

Warning devices for monitoring of specific events in the fluid-filled containers are basically known. For example, such warning devices are used to detect a borderline for the braking function minimum level in pressure fluid tanks for hydraulic motor vehicle brake systems. Thus, they are safety-relevant and the correct function of each warning device must be proven by a functional test.

For example DE 10 2007 040 044 A1 is such a warning device together with associated test methods known. To detect the minimum level, the warning device has a, reed switch, which is activated by a magnet. The reed switch is arranged in a vertical cylindrical guide tube in the height of the measured minimum level in the container. The magnet is housed in an annular float, which is arranged around the guide tube and is guided on this.

The warning device is passively tested for its function after its manufacture and prior to assembly in the container by external action by a special, separate test system is connected to the warning device and charged the reed contacts with certain excitation profiles. Furthermore, the switching event is simulated "dry" by a magnet equivalent to the insert magnet. Various electrical parameters such as dynamic or static contact resistances as well as the switching times are tapped and compared with provided standard values.

If the measured values meet the specifications, the warning device is mounted in the container. Further, later functional checks during vehicle operation are not provided.

Switches, change-over and sensors in general, which are operated regularly, can be checked due to the frequently occurring state changes. It can be compared with the help of numerous previous results, whether a signal change is plausible or caused by an error. Falling below a minimum level in vehicle operation, however, experience is an event that extremely rare, ideally never occurs. A disadvantage of known solutions described above is considered that various component properties of the warning device can change during a long service life-for example, contact resistances can form on contacts, glue the contacts, fatigue the internal parts of the switch, or clamp the mechanism required to operate the switch, and thus lead to malfunction. The possibility that a functional deviation remains undetected until the actual occurrence of the event can not therefore be completely ruled out.

It is therefore an object to propose an improved warning device, the functionality of which can be checked as reliably as possible even in rarely occurring events.

The object is achieved with a warning device with the feature combination according to claim 1 solved. Subclaims propose according to the invention further advantageous embodiments and refinements de warning device according to the invention and an associated test method according to the invention.

The invention provides that the warning device is designed to actively initiate the state change of the integrated signal unit, independently of the event to be monitored.

Thus, the function of the signal unit, as well as the controlling mechanism, at any time, active and autonomous to be checked during operation without the event to be monitored must occur. In addition, it is possible to dispense with having separate reference values for checking the plausibility of signals.

The warning device according to the invention is preferably used for monitoring one or more different defined fluid levels in the container, particularly preferably in a pressure medium container of a hydraulic motor vehicle brake system.

Thereby, the reliability and safety of the driving operation of vehicles can be significantly improved with little effort.

According to one embodiment of the invention, the warning device to an electromagnetic switching device, wherein the switching device is simultaneously coupled to the position sensor and the signal unit. In this case, a state change of the signal unit and / or the position sensor to be checked is caused by the activation of the switching device. In the preferred embodiment of the development, the switching device has a coil and an armature displaceable relative to the coil, wherein the armature is at the same time coupled to the position transmitter and the signal unit.

This can be done with reinforced, robust and cost-effective components not only the Signal unit checks, but also the mechanics, which initiates the change in state of the signal unit. For example, this can be used to check the freedom of movement of the position transmitter necessary in the event of operation.

According to the invention, the signal unit can be designed as a relatively simple, cost-effective and robust contact switch, which interrupts an electrical circuit in an open state and closes the electrical circuit in the closed state.

For ease of manufacture and assembly, the warning device according to the invention may comprise a housing which, in a space-saving manner, projects into the container in a space-saving manner; For a particularly simple mechanical construction of the position sensor can be designed as a float, which is arranged in the installed position in the container below the housing.

For a simple and unambiguous interpretability of the measured values, the warning device according to the invention can have a stop which defines an end position for the armature in the activated switching device. In this case, the position of the stop is provided such that the occurrence of the change in state of the signal unit, the time before the application of the armature against the stop.

Thus, when striking the anchor at the stop is always a clear result, whether the expected signal of the signal unit or not and thus must be assumed by an error.

Furthermore, the invention provides methods for testing the warning device according to the invention.

According to a test method according to the invention, in a preceding method step, the warning device is set up ready for operation in the container, the state change of the signal unit is actively activated in a further method step and a check is made in a subsequent method step as to whether a signal change has taken place on the signal unit.

Thus, a check of the functionality is autonomous and independent of the place of manufacture or separate testing facilities possible. According to a further test method according to the invention, it can be checked whether an induction change of the coil of the switching device has taken place.

This makes it possible to clearly determine whether the mechanical movements to be expected take place and whether they are correct and plausible in their course.

Other features, advantages and applications of the invention will become apparent from the following description of an embodiment according to 1 out.

1 shows a possible embodiment of the invention highly schematic in a sectional view. In this embodiment, the warning device according to the invention 1 in a pressure fluid reservoir of a hydraulic motor vehicle brake system, not shown here, for monitoring a minimum level of the fluid designated as switching point S. 2 used. Further application scenarios, not shown here, in particular for systems in which it must be ensured that a switching signal with a low expected frequency of occurrence can be reliably detected if necessary, are of course also permissible within the scope of the invention

The warning device 1 has a housing 10 which partly within one with a fluid 2 filled container 3 is arranged. The hydraulic interfaces 21,22 connect the internal volume of the container 3 with the rest of the brake system not shown here and allow the fluid circulation. For a reliable function of the brake system is a minimum amount of the fluid 2 required, which depends on the nature of the container 3 and optionally a defined safety factor in the container 3 defined a minimum level. This is referred to as switching point S and usually on the container 3 indicated by a "MIN" abbreviation from the outside.

The level of the fluid 2 inside the container 3 is subject to fluctuations in braking operation in general, in case of a leak, he may also sink below the caliber of the switching point S, whereby the vehicle operation is classified as unsafe and should be prevented. The warning device 1 monitors this event and, when it arrives, generates an electrical signal, generally through an electronic signal processing unit 20 is interpreted and processed.

The warning device has to monitor the level 1 via a position sensor designed as a float 4 , The position transmitter 4 is in the ready-to-install position below the housing 10 positions and floats on or in the fluid 2 , thus marks the current level by its position. The position transmitter 4 is through a coupling element 12 with a signal unit 5 coupled, which when marking the switching point S through the locator 4 generates an electrically detectable signal.

In the embodiment shown, the signal unit is 5 is formed as a contact switch which can assume two detectable state changes: an open and a closed state, wherein correspondingly an electrical circuit 9 is interrupted or closed. For this the signal unit has 5 via contact elements 15 . 16 passing through a bridge 17 electrically connected or disconnected and by electrical signal terminals 18,19 to the electrical circuit 9 are connected. In the present embodiment, the bridge 17 to the coupling element 12 and thus to the position transmitter 4 coupled. When in the container 3 enough fluid 2 is the position of the position encoder 4 correspondingly high and between the contact elements 15 . 16 and the bridge 17 there is a gap a before - the contact switch is open. The distance a between the contact elements 15,16 and the bridge 17 is chosen so that the electrical circuit 9 closed when the locator 4 drops to the switching point S or below. This state change is made by the signal processing unit 20 recorded and used for this purpose.

Further constructive embodiments of the signal unit 5 leading to an interruption or closure of the circle 9 depending on the position of the position sensor 4 are still allowed within the invention, even if the principle of operation is reversed. For example, it is conceivable and, in some embodiments, more advantageous, the electrical circuit 9 to keep normally closed and to interrupt only when one or more different defined filling levels have been reached - for example by the signal unit 5 a sliding contact, which slides on a guide strip, which has one or more insulating sections corresponding to the target levels.

To the functioning of the warning device 1 To be able to check at any time after their installation is in the warning device 1 an electrically activatable switching device 6 integrated, which allows a change in state of the signal unit 5 without removal and at any desired time, regardless of the level and position of the position sensor 4 to actively initiate self-testing to test the system response.

For this purpose, the switching device 6 essentially provided as an electromagnetic switch or a solenoid. The switching device 6 has a coil 7 and one relative to the coil 7 displaceable anchor 8th on. The sink 7 is formed in the embodiment shown substantially annular, in the housing 10 fixed in place and can by supply connections 13 . 14 be supplied with electrical power. The movable anchor 8th is with the coupling element 12 connected and thereby at the same time to the position transmitter 4 and the signal unit 5 coupled.

In the example shown, the coil 7 and the anchor 8th Arranged such that when the coil 7 energized, the anchor 8th down towards the locator 4 emotional.

In the case 10 is a stop 11 provided, which is an end position for the anchor 8th defined during its downward movement. A clearance b between the anchor 8th and the stop 11 is greater than the distance a provided so that the signal unit 5 undergoes the state change to be tested before the anchor 8th at the stop 11 is created.

Will the switching device 6 activated, the anchor 8th until the stop 11 offset and no signal change at the signal unit 5 Recognized, so you have a defect in the signal unit 5 , on a closed wiring harness or otherwise assumed. As a result, for example, a corresponding message from the vehicle's on-board computer to a service center can be sent in good time or the vehicle driver can be called on to visit a workshop.

Will the switching device 6 switched off again, so the position encoder drives 4 according to the Archimedean principle and the signal unit 5 is returned to the initial state as before the test.

By means of the switching device according to the invention 6 can also change the movement of the anchor 8th also about the current or induction change of the coil 7 Plausibilisiert and thus the mechanical clearance of the mechanical components are tested. If the anchor moves 8th , there is an induction change of the coil 7 , which counteracts the current. This induction change (or lack thereof) can be achieved by the appropriate signal processing unit 20 be recognized and analyzed. As a result, it can be detected, for example, whether the position transmitter 4 Do not move properly (for example, due to contamination, corrosion, tilting, etc.) and thus can mark the level.

To simplify the contacting of the warning device 1 are all electrical connections like the supply connections 13 . 14 and the signal connections 18 . 19 arranged side by side in a common connector housing, not shown here, thus forming a single combined electrical interface 24 of the warning device 1 ,

LIST OF REFERENCE NUMBERS

1

warning device

2

fluid

3

container

4

locator

5

signal unit

6

switching device

7

Kitchen sink

8th

anchor

9

Electric circuit

10

casing

11

attack

12

coupling element

13

supply terminal

14

supply terminal

15

contact element

16

contact element

17

bridge

18

signal connection

19

signal connection

20

Signal processing unit

21

Hydraulic interface

22

Hydraulic interface

a

distance

b

clearance

s

switching point

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102007040044 A1 [0002]

Claims (11)

Warning device (1) for monitoring an event in a container (3) with a fluid (2) comprising a movable position sensor (4) whose position depends on the level of the fluid (2) in the container (3) and a signal unit ( 5) which, depending on the position of the position sensor (4) undergoes at least one state change detected as an electrical signal, characterized in that the warning device (1) is adapted to change the state of the signal unit (5) independently of the actively initiate the monitoring event. Warning device according to claim 1, characterized in that the event to be monitored is a defined level of the fluid (2) in the container (3). Warning device according to claim 1, characterized in that the warning device comprises an electromagnetic switching device (6), wherein the switching device (6) to the position sensor (4) and the signal unit (5) is coupled and activation of the switching device (6), the change in state of the signal unit (5) and / or the position sensor (4) causes. Warning device according to claim 3, characterized in that the switching device (6) comprises a coil (7) and a relative to the coil (7) displaceable anchor (8), wherein the armature (8) to the position sensor (4) and the signal unit (5 ) is coupled. Warning device according to claim 1, characterized in that the signal unit (5) in an electrical circuit (9) and as a contact switch is formed, wherein the electrical circuit (9) is interrupted when the contact switch is open and the electric circuit (9) closed is when the contact switch is closed. Warning device according to claim 1, characterized in that the warning device (1) has a housing (10) which protrudes at least partially into the container (3) and the position sensor (4) is designed as a float, which in the installed position in the container (3). is arranged below the housing (10). Warning device according to claim 4, characterized in that the warning device (1) has a stop (11) defining an end position for the armature (8) in the activated switching device (6), the position of the stop (11) being such in that the occurrence of the change in state of the signal unit (5) temporally anticipates the application of the armature (8) to the stop. Warning device according to one or more of Claims 1 - 7 characterized in that the container (3) is designed as a pressure medium container of a hydraulic motor vehicle brake system. Method for functional testing of a warning device according to one or more of Claims 1 - 8th characterized in that: • in a preceding method step, the warning device (1) in the container (3) is set up ready for operation • in a further process step, the state change of the signal unit (5) is actively caused, • is checked in a subsequent step, whether a Signal change at the signal unit (5) has taken place. A method according to claims 3 and 9, characterized in that the state change of the signal unit (5) by activation of the switching device (6) is generated. Method for functional testing of a warning device according to one or more of Claims 4 - 8th characterized in that: • in a preceding method step, the warning device (1) in the container (3) is set up ready for operation • in a further method step, the switching device (6) is activated, • is checked in a subsequent method step, whether an induction change of the coil (7) has taken place.

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