DE102012011251A1 - Electrical circuit device for carburettor air preheater of vehicle, has detecting units to determine relay malfunction with contact bridge as countermeasure, so that pulses of control circuits are activated - Google Patents

Abstract

The device (2) has an electromechanical relay (14) that is controlled electromechanically against the force of a return spring, such that a connection between load contacts of relay is made for switching electrical load circuits (10,11) after activation of electrical control circuits (18,19) with a contact bridge at contact points. Detecting units (15,16) are adapted to determine the relay malfunction with contact bridge as a countermeasure, so that pulses (35) of control circuits are activated for appropriate free shaking of contact bridge to solution by aperture of load circuits. An independent claim is included for method for repairing an electromechanical relay with contact bridge.

Description

The invention relates to a device with an electromechanical relay in an electrical load circuit and an electrical control circuit according to the preamble of claim 1.

A well-known relay has a controlled electromechanically displaceable against the force of a return spring contact bridge, such that after activation of the control circuit with the contact bridge at contact points a connection between the load contacts of the relay for switching the load circuit of a consumer is made. In this case, usually the load contacts and a magnetizable with the control circuit magnetic coil are fixedly arranged on a relay housing. The contact bridge is usually mounted as a contact ring on an attractable by the excited magnetic coil anchor.

For an undisturbed function of the relay, the force of the return spring is sufficient to return the armature to its initial position after a deactivation of the control circuit and thus to release the contact bridge of the load contacts to interrupt the load circuit. Relays are known in different structural designs such that the "contact bridge" can be made in one or more parts, in particular also with contact spring tongue. All these different embodiments are intended to be encompassed here by the term "contact bridge".

Generally known is the risk of a relay malfunction, in which after deactivation of the control circuit, the contact bridge at the contact points "sticks" and the load circuit does not open. The reason for such a "relay adhesive" is usually that it comes in switching operations to an arc and the heat released in the process, the metal contacts of the relay welded together, so that a later opening by the return spring is no longer possible.

For this case, there is a disadvantage in not designed for continuous operation electrical devices, an overheating hazard, where appropriate, with it caused damage. For example, if the electrical devices is a switchable with the relay electric Ansaugluftvorwärmer (Heater) of an internal combustion engine in a commercial vehicle, there is a risk that heaters melt by overheating, are sucked with the intake air into the internal combustion engine and damage them.

A relay with a "relay adhesive" is usually not repairable and must be replaced. Such an exchange is complex and can not be performed immediately, in particular in the case of mobile use of a relay, for example for an intake air preheater of a commercial vehicle used for driving.

To reduce the problem, costly and expensive measures are already known: For example, oversized relays or multiple relays connected in series are used in a redundancy circuit. Next, a "short circuit" with a second relay is known, which ensures in case of failure for switching off an overcurrent protection. In addition, monitoring systems and monitoring functions for informing an operator are known.

It is further known ( DE 19 54 65 53 C1 ) to determine the switching state of a consumer by measuring the voltage value of a battery of a vehicle electrical system of a vehicle, since each switching a consumer in the electrical system generates a slight voltage jump.

In addition, it is known ( DE 10 2007 011 456 A1 ) after detecting the blocking of a fuel pump to drive them for a certain period of time in a direction changed to the Normalforderrichtung conveying direction to cancel the blockage.

The object of the invention is to make a relay with a "relay adhesive" quickly functional again with a simple and cost-effective measure.

This object is achieved with the features of claim 1. Advantageous embodiments are the subject of the dependent claims.

According to the invention, it is provided that the relay malfunction is detected with a "sticky" contact bridge with a detection device and then the electrical control circuit with successive pulses for a "free shaking" of the contact bridge is activated until its solution and provision with opening of the contact circuit.

In such a provisional relay repair by "free-shaking" the fact is exploited that even with welded-on contacts, the anchor construction by design has a residual degree of freedom of movement. It has been shown that it is usually possible by a jerky control of the armature with successive pulses to bring the system to swing and sometimes solve the welded contacts by the resulting force amplitudes from each other, so that the undisturbed relay function is available again.

Such an intrinsic relay repair is usually possible when the drive frequency of the successive pulses is adapted to the mechanical resonance of the armature with contact bridge. The resonant frequency depends clearly on the type of relay used and can easily be determined experimentally.

The measure "Freirütteln" by a swing in the resonant frequency is regularly successful when the armature is designed with contact bridge of the relay as a spring-mass system, because then at least by the spring a degree of freedom of movement is available. Here, for example, the contact bridge can be simple and cost-effective as a double plate spring (in addition to the usual return spring).

Basically, the above provisional relay repair by "free shaking" in all electrical load circuits is possible, but especially for heating systems in a DC load circuit. Preferably, this may be an electric intake air preheater (heater) of an internal combustion engine in a commercial vehicle, since the risk of engine damage due to molten heating elements in the event of overheating is already given here, as already described above. Thus, on the one hand, overheating is advantageously avoided and, on the other hand, at least for further switching operations up to, if necessary, replacement of the relay, the undisturbed relay function is made available again.

To initiate the measure of "free shaking" it is first necessary to recognize a "relay adhesive". This can be done by means of a detection device in a conventional manner by the voltage and / or the load current is measured, wherein after a deactivation of the control circuit of the load current is not interrupted and / or a battery voltage does not rise. For this case, an error signal for a "relay adhesive" is delivered to the control unit by the detection device. If necessary, the detection device can also be integrated in the control unit together with the measuring element.

From the control unit, both the control signals for error-free switching on / off of the relay are given as well as the application of an error signal, the pulses for a "free shaking" of the contact bridge.

In a further embodiment, after a successful self-repair by "shaking" the contact bridge, a warning signal, in particular by a yellow lamp, is given to an operator. With this warning signal it should be pointed out that a replacement of this relay is indicated, since such a self-repair can not be repeated any number of times. Therefore, even after a set number of successful self-repairs by "free shaking" the self-repair function can be completely switched off or the relay can not be controlled.

In the event that a provisional self-repair by free shaking was unsuccessful, this should be displayed to an operator with a corresponding warning signal, in particular by a red lamp.

In addition, a method for in-system repair of an "adhesive contact bridge" relay using the above devices is claimed.

Reference to a drawing, the invention will be further explained.

Show it:

1 a schematic plan view of an electric Ansaugluftvorwärmer and the associated circuitry,

2 a section through one in the circuit 1 used relay of a first embodiment, and

3 a relay accordingly 2 a second embodiment.

In 1 is an intake air preheater 1 with the associated electrical circuitry 2 shown schematically.

The intake air preheater 1 lies in a (not shown) intake duct of an internal combustion engine of a commercial vehicle and consists essentially of an annular housing part 3 which lies transversely in the intake passage and a resistance element as a heating element 4 ,

The heating element 4 consists of meander-shaped Heizlamellen 5 , which are spaced apart in nine layers one above the other, each laterally electrically isolated in the housing part 3 are held and with their lamella ends 6 and 7 each at associated electrical connections 8th . 9 on the housing part 3 are connected.

The intake air preheater 1 lies in the load circuit (minus line 10 and plus lead 11 ) of a battery 12 in the electrical system of the commercial vehicle.

After the battery 12 is in the plus line 11 a fuse 13 and subsequently a relay (shown schematically) 14 disposed of which two concrete embodiments in the 2 and 3 are shown.

Next is schematically an ammeter 15 in the plus line 11 specified, with which the current load current is detected and a corresponding load signal with a line 16 to a control unit 17 (ECU) is given. The electrical control unit 17 is connected to a control circuit (minus line 18 and plus lead 19 ), in which the relay 14 each with associated control contacts 20 . 21 lies.

Next is at the control unit 17 a (schematically indicated) warning lamp 22 connected.

In 2 is a longitudinal section through the relay 14 (First embodiment) shown with further details: On a wall of a relay housing 23 is stationary in the housing protruding a solenoid with the control contacts 20 . 21 arranged. On both sides of it are load contacts 25 . 26 to connect the minus line 10 and the plus line 11 arranged the load circuit.

In the relay housing 23 is also an anchor 27 arranged at a controlled excitation of the magnetic coil 24 is attracted and displaceable towards this (arrow 28 ).

The anchor 27 is in the illustrated starting position by a return spring 29 held as a compression spring in the area around the magnetic coil 24 lies. On the anchor 27 is one on the load contacts 25 . 26 indicative contact bridge 30 attached, as the contact ring, the magnetic coil 24 and the return spring 29 surrounds.

When driving the solenoid coil 24 is thus by the anchor 27 the contact bridge 30 at contact points 31 . 32 and 33 . 34 brought to the plant, creating an electrical connection between the load contacts 25 . 26 is manufactured and thus the load circuit for the heating function of Ansaugluftvorwärmers 1 closed is.

In 3 is a second embodiment of a relay 14 ' shown that largely the same structure as the relay 14 of the 2 has, so that the same elements with the same reference numerals (with a dash) are marked.

The difference in the second embodiment lies in the fact that the contact bridge 30 in contrast to the first embodiment not as a simple rigid contact ring, but as a spring element in the form of a double-plate spring 36 is executed, so that the anchor 27 ' and the contact bridge 30 ' as a spring-mass system allow higher vibration amplitudes allow.

The illustrated arrangement is controlled as follows:
For activation of the heating function of the intake air preheater 1 becomes the control circuit (lines 18 . 19 ) of the controller 17 and with it the relay 14 . 14 ' activated and the load circuit (lines 10 . 11 ) closed. Here are the contact points 31 . 32 and 33 . 34 respectively. 31 ' . 32 ' and 33 ' . 34 ' together. After deactivation of the control unit 17 to switch off the intake air preheater 1 These contact points are in trouble-free operation by repatriation of the anchor 27 . 27 ' and the contact bridge 30 . 30 ' due to the force effect of the return spring 29 solved. Due to the relatively high load current, however, the contact points may weld in a relay malfunction, causing the contact bridge 30 . 30 ' at the load contacts 25 . 26 "Sticks" and thus the load circuit after deactivation of the control circuit does not open. There is a risk that the heating fins 5 of the intake air preheater 1 melted by an inadmissible long energization at least partially melting and thus lamellar components in the engine, which can be significantly damaged. Since the current does not increase unacceptably high with an "adhesive" contact bridge, the fuse will respond 13 not yet.

In order not to let the above case occur, the load current is measured here (current meter 15 ) and the corresponding current signal to the controller 17 fed. If after deactivation of the control circuit (lines 18 . 19 ) continue a load current signal over the line 16 at the control unit 17 This is a criterion for an "adhesive" contact bridge 30 . 30 ' , This controls the controller 17 to a repair mode, wherein the control circuit with successive pulses (indicated by the pulse sequence 35 ) is applied. This is the anchor 27 . 27 ' with the contact bridge 30 . 30 ' put into appropriate vibrations and the contact bridge "freigerüttelt", so that the anchor 27 . 27 ' with the contact bridge 30 . 30 ' by the spring force of the return spring 29 . 29 ' returned again and thus the load circuit is opened.

In case of a successful repair by "free shaking", the measured load current signal (line 16 ) and the repair mode is ended. A successful repair can then be done by the warning lamp 22 are displayed. In addition, the repair mode can be time-limited, so that this or the controlling function is also switched off after unsuccessful repair. This may also be indicated by (another) warning light if necessary.

A repair of an "adhesive" contact bridge 30 . 30 ' is faster and more successful if the drive frequency for the pulse sequence 35 to the mechanical resonance of the anchor adapted with contact bridge. In particular, the success rate is increased if, as with the second relay version 14 ' to 3 the anchor 27 ' with the contact bridge 30 ' is designed as a spring-mass system, which targeted to the load contacts 25 . 26 is excited to relatively large resonant vibrations with relatively high vibrational energy. This is the contact bridge 30 ' here from a double plate spring 36 ,

With the above measure, a temporary self-repair of the relay by free-shaking is possible, which in any case prevents engine damage and / or a stoppage of the vehicle. Since such self-repair can not be repeated as often as desired, the repair mode or the heating function are forcibly suspended after a set number of successful self-repairs. Before this happens, the relay should be used 14 . 14 ' be replaced.

LIST OF REFERENCE NUMBERS

1

Intake air

2

electrical circuit arrangement

3

housing part

4

heating element

5

heating fins

6

lamella end

7

lamella end

8th

electrical connection

9

electrical connection

10

Negative line

11

Plus line

12

battery

13

Melting fuse

14

relay

15

ammeter

16

management

17

control unit

18

Negative line

19

Plus line

20

control contact

21

control contact

22

warning light

23

relay housing

24

solenoid

25

load contact

26

load contact

27

anchor

28

arrow

29

Return spring

30

Contact bridge

31

contact point

32

contact point

33

contact point

34

contact point

35

pulse sequence

36

Double-disc spring

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 19546553 C1 [0008]
• DE 102007011456 A1 [0009]

Claims (12)

Device with an electromechanical relay ( 14 ) in an electrical load circuit ( 10 . 11 ) and an electrical control circuit ( 18 . 19 ), the relay ( 14 ) a controlled electromechanically against the force of a return spring ( 29 ) movable contact bridge ( 30 ), such that after activation of the control circuit ( 18 . 19 ) with the contact bridge ( 30 ) at contact points ( 30 . 31 and 33 . 34 ) a connection between load contacts ( 25 . 26 ) of the relay ( 14 ) for switching the load circuit ( 10 . 11 ) of a consumer ( 1 ) and in the event of a relay malfunction after deactivation of the control circuit ( 18 . 19 ) the contact bridge ( 30 ) at the contact points ( 30 . 31 and 33 . 34 ) "Sticks" and the load circuit ( 10 . 11 ) does not open, characterized in that with a detecting device ( 15 . 16 ) the relay malfunction with "sticky" contact bridge ( 30 ) and then, as a countermeasure, the electrical control circuit ( 18 . 19 ) with successive pulses ( 35 ) for a corresponding "free shaking" of the contact bridge ( 30 ) until their solution and provision with opening of the load circuit ( 10 . 11 ) is activated. Device according to Claim 1, characterized in that the driving frequency of the successive pulses ( 35 ) to the mechanical resonance of an armature ( 27 ) with contact bridge ( 30 ) of the relay ( 14 ), the anchor ( 27 ) by a controlled magnetic coil ( 24 ) is displaceable. Device according to claim 2, characterized in that the armature ( 27 ) with contact bridge ( 30 ' ) is designed as a spring-mass system and optimized for high vibration amplitude. Device according to claim 3, characterized in that the contact bridge ( 30 ' ) as a double plate spring ( 36 ) is trained. Device according to one of claims 1 to 4, characterized in that the electrical consumer ( 1 ) a heating system in a DC load circuit ( 10 . 11 . 12 ). Apparatus according to claim 5, characterized in that the heating system is an electric Ansaugluftvorwärmer ( 1 ) an internal combustion engine, in particular in a motor vehicle. Device according to one of claims 1 to 6, characterized in that with the detecting means an "adhesive" contact bridge ( 30 ) after a predetermined deactivation of the control circuit ( 18 . 19 ) by measurement ( 15 ) of the load current and / or the voltage is detected and in such a relay malfunction a corresponding error signal (line 16 ) to a control unit ( 17 ) is delivered or generated there. Apparatus according to claim 7, characterized in that with the control unit ( 17 ) both the predetermined activation signals for error-free switching on / off of the relay ( 14 ) are generated, as well as in the presence of an error signal, the pulses ( 35 ) for a "free shaking" of the contact bridge ( 30 ). Device according to one of claims 1 to 8, characterized in that after a successful self-repair by "shaking" the contact bridge ( 30 ) a warning signal, in particular by a yellow warning lamp ( 2 '' ) is delivered to an operator. Device according to one of claims 1 to 9, characterized in that after a fixed number of successful self-repairs by "shaking" the contact bridge ( 30 ) the self-repair function is switched off or its activation is prohibited. Device according to one of claims 1 to 8, characterized in that a time threshold, in particular with a timer in the control unit ( 16 ) can be specified, according to which in case of unsuccessful self-repair a warning signal, in particular by a red lamp is delivered to an operator. Method for internal system repair of a relay ( 14 ) with "adhesive" contact bridge ( 30 ) using a device according to claims 1 to 11.

Images