DE102013225312A1 - Method for monitoring a speed sensor - Google Patents

Abstract

The invention relates to a method for testing a function of a rotational speed sensor (10), which is set up to generate an output signal (36, 40) based on a physical measuring field emitted by a rotating object (26) with a measuring transducer (50) - exciting the sensor (50) with a physical test field (52) known in its form, and - plausibility of the function of the speed sensor (10) based on a comparison of the output signal (36, 40) and the physical test field (52).

Description

The invention relates to a method for monitoring a rotational speed sensor, a control device for carrying out the method and a sensor with the control device.

From the DE 10 2011 080 789 A1 a vehicle is known in the wheel speed sensors are installed to detect the wheel speed of the individual wheels.

It is an object of the invention to improve the detection of wheel speeds.

The object is solved by the features of the independent claims. Preferred developments are the subject of the dependent claims.

• – Anregen des Messaufnehmers mit einem in seiner Form bekannten physikalischen Testfeld, und
• – Plausibilisieren der Funktion des Drehzahlsensors basierend auf einer Gegenüberstellung des Ausgangssignals und des physikalischen Testfeldes.

According to one aspect of the invention, a method of testing a function of a speed sensor configured to generate an output signal based on a physical measurement field output from a rotating object with a sensor, comprising:

• - Excite the sensor with a known in its form physical test field, and
• - Plausibilisieren the function of the speed sensor based on a comparison of the output signal and the physical test field.

The specified method is based on the consideration that the rotational speed sensor outputs an output signal which depends on a rotational speed of the physical measuring field with a predetermined characteristic. A downstream device processing the output signal can then derive the speed to be detected from the output signal, knowing the characteristic.

However, if the characteristic has an error, then the wrong output speed is output with the output signal, and the downstream processing device can not detect the speed error. In further processing, such as in a vehicle dynamics control, this error can then be safety-critical.

In order to find such an error, it is therefore proposed in the context of the specified method to excite with a test field known from the beginning. In the context of this excitation, it can then be checked on the output side whether or not a corresponding output signal for the test field known from the beginning is established in order to find an error which may be present.

The physical test field can be designed as desired. In an active speed sensor with a magnetic encoder disk that generates the above magnetic field in the form of a magnetic field, this encoder disk can also be used to generate physical test field by rotating the encoder disk at the speed known from the beginning. In a particular embodiment of the specified method, however, the physical test field is a different magnetic field from the physical measuring field, which is excited based on a test current. The test current could, for example, simulate the encoder disk, so to speak, so that the speed sensor can be tested even if the encoder disk is not yet installed or can not be rotated at a certain speed, such as while driving a vehicle.

In a preferred embodiment of the specified method, the rotational speed sensor is operated with a supply current which comprises the test current. In this case, the test current may be part of the supply current or else the entire supply current. In this way, to provide the supply current does not need to be provided a completely dedicated, space-intensive electrical power supply for performing the specified method.

In a particularly preferred development of the stated method, a current path for the test current is connected in parallel with a current path for the current sensor of the rotational speed sensor when the test current is excited, so that the test current can be provided for carrying out the specified method, without the supply current must be interrupted for the speed sensor during the provision of the test current.

In an additional development of the specified method, the current path for the supply current of the rotational speed sensor is separated therefrom, after the current path for the test current is connected to the rotational speed sensor. In this way, the entire supply current can be used as a test current, so that the above-mentioned formed as a magnetic field physical test field can be generated with a maximum possible field strength.

In a further embodiment of the specified method, the function of the speed sensor is plausibility after the current path for the supply current of the speed sensor is disconnected from the speed sensor, so that the verification of the sensor in a steady state of Test current and thus the physical test field is done.

In another development of the specified method, the physical measuring field is different from the physical test field, wherein the measuring sensor is excited with the physical test field when the physical measuring field is equal to zero. This ensures that the physical measuring field has no influence on the physical test field and thus disturbs the measurement.

In a preferred embodiment of the specified method, the sensor is excited with the physical test field when the output signal passes through a zero crossing. This development is particularly advantageous for active speed sensors which detect the wheel speed in the form of a clocked output signal, wherein the speed can be derived from the number of clocks in the output signal over a predetermined period of time. In such a rotational speed sensor, the output signal directly reflects the course of the magnetic measuring field, so that in the zero crossing points of the output signal the magnetic measuring field is assumed to be zero and the test of the rotational speed sensor can be carried out.

According to another aspect of the invention, a control device is arranged to perform one of the specified methods.

In a development of the specified control device, the specified device has a memory and a processor. In this case, a specified method in the form of a computer program is stored in the memory and the processor is provided for carrying out the method when the computer program is loaded from the memory into the processor.

According to a further aspect of the invention, a computer program comprises program code means for performing all the steps of one of the specified methods when the computer program is executed on a computer or one of the specified devices.

According to another aspect of the invention, a computer program product includes program code stored on a computer-readable medium and, when executed on a data processing device, performs one of the specified methods.

According to another aspect of the invention, a sensor comprises one of the specified control devices.

In a particular embodiment, the specified sensor is a wheel speed sensor.

In accordance with another aspect of the invention, a vehicle includes a specified wheel speed sensor.

The above-described characteristics, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more clearly understood in connection with the following description of the exemplary embodiments, which are explained in more detail in conjunction with the drawings, in which:

1 a schematic view of a vehicle with a vehicle dynamics control,

2 a schematic view of a speed sensor in the vehicle dynamics control of 1 .

3a in a plan view of a read head with a sensor of the speed sensor 1 with a test current conductor,

3b the sensor of the 3a with the test current conductor in a side view,

4a in a plan view of the read head with the sensor of the speed sensor 1 with another test current conductor,

4b the sensor of the 4a with the further test current conductor in a side view,

5a in a plan view of the read head with multiple sensors of the speed sensor 1 with yet another test current conductor,

5b the sensors of the 5a with the still further test current conductor in a side view,

6 a circuit for energizing the test conductor of the 3a to 5b ;

7 a part of the circuit 6 show in a further education.

In the figures, the same technical elements are provided with the same reference numerals and described only once.

It will open 1 Reference is made to a schematic view of a vehicle 2 with a known vehicle dynamics control shows. Details of this driving dynamics control, for example, the DE 10 2011 080 789 A1 be removed.

The vehicle 2 includes a chassis 4 and four wheels 6 , Every bike 6 Can be fixed on the chassis 4 fixed brake 8th opposite the chassis 4 slowed down to a movement of the vehicle 2 to slow down on a road, not shown.

It may happen in a manner known to those skilled in the art that the wheels 6 of the vehicle 2 lose their grip and get the vehicle 2 even moved away from a given example by a steering wheel not shown steering trajectory by understeer or oversteer. This is avoided by known control circuits such as ABS (antilock braking system) and ESP (electronic stability program).

In the present embodiment, the vehicle 2 for speed sensors 10 at the wheels 6 on that one speed 12 the wheels 6 to capture. Further, the vehicle points 2 an inertial sensor 14 on, the driving dynamics data 16 of the vehicle 2 from which, for example, a pitch rate, a roll rate, a yaw rate, a lateral acceleration, a longitudinal acceleration and / or a vertical acceleration can be output in a manner known to a person skilled in the art.

Based on the recorded speeds 12 and vehicle dynamics data 16 can be an evaluation device in the form of a regulator 18 in a manner known to those skilled determine whether the vehicle 2 slips on the road or even deviates from the above-mentioned predetermined trajectory and correspond with a known controller output signal 20 to react to that. The regulator output signal 20 can then be from a control device 22 to be used by means of actuating signals 24 Actuators, like the brakes 8th to drive, which respond to the slippage and the deviation from the given trajectory in a conventional manner.

The regulator 18 For example, in a known motor control of the vehicle 2 be integrated. Also, the controller can 18 and the actuator 22 formed as a common control device and optionally be integrated in the aforementioned engine control.

Look for one of the in 1 shown speed sensors 10 the present invention will be clarified in more detail.

It will open 2 Reference is made, which is a schematic view of one of the speed sensors 10 in the vehicle dynamics control of 1 shows.

The speed sensor 10 is in the present embodiment designed as an active speed sensor, which rotatably on the wheel 6 attached encoder disk 26 and a stationary to the chassis 4 attach reading head 28 includes.

The encoder disk 26 consists in the present embodiment of juxtaposed magnetic north poles 30 and magnetic south poles 32 , which together excite a donor magnetic field not shown. Turns on the wheel 6 attached encoder disk 26 with this in one direction 34 , the encoder magnetic field rotates with it.

The reading head 28 is in the present embodiment, a magnetostrictive element, which depends on the angular position of the encoder wheel 26 energized transmitter magnetic field changes its electrical resistance.

For detecting the speed 12 is the change in the angular position of the encoder wheel and thus the change in the electrical resistance of the read head 28 be recorded. This can be done by the sensor 28 in a conventional manner to a resistance measuring circuit, not shown, such as a known bridge circuit can be connected. Depending on the electrical resistance of the reading head 28 the resistance measurement circuit becomes a speed sensor signal 36 output. Based on the speed sensor signal 36 can in a conventional manner in a read head 28 downstream signal conditioning circuit 38 one from the speed 12 dependent output signal 40 , for example in the form of a pulse signal, generated and to the controller 18 output. For this purpose and for further background information on active wheel speed sensors, the relevant prior art, such as the DE 101 46 949 A1 directed.

To determine the speed 12 out of the speed 12 dependent output signal 40 must be in the the output signal 40 processing device, such as the regulator 18 the dependence between the output signal 40 and the speed 12 be known. This dependency is usually determined in advance and in the controller 18 For example, in the form of a processing algorithm, a characteristic or the like deposited. It is assumed that the controller 18 assumed dependence between the output signal 40 and the speed 12 also the actual dependence between the output signal 40 and the speed 12 corresponds to how the speed sensor 10 is produced. Voices from the regulator 18 assumed dependence and in the speed sensor 10 produced dependence do not match, so have the regulator 18 received speeds 12 an error. To detect such an error is proposed in the present embodiment, with the speed sensor 10 a previously known speed 12 to capture and check if the output signal 40 this pre-known speed 12 can be removed.

This can be done in the simplest way, that the encoder wheel 26 with the previously known speed 12 is turned. In many cases, such as in the case of the above-mentioned vehicle 2 while driving this is not possible. Therefore, it is proposed in the present embodiment, the encoder wheel 26 to simulate and the previously known speed 12 with a test current 46 to generate. This will be explained below on the basis of 3a to 5b described in more detail by concrete examples.

It will be on the 3a and 3b Reference is made to the reading head 28 of the speed sensor 1 with a test current conductor 48 in a side view and the reading head 28 of the 3a with the test current conductor in a side view.

The reading head 28 has a sensor in the present embodiment 50 on, the above-mentioned magnetic field, which in the present figures by the reference numeral 52 is provided, from the encoder wheel 26 measures, so based on this measurement that of the speed 12 dependent output signal 40 can be generated.

In the reading head 28 could also be the signal conditioning circuit 38 be integrated, which is designed in the present embodiment in a conventional manner as a semiconductor chip. In this signal conditioning circuit 38 this is the test current 46 leading test leader 48 integrated, so based on the test current 46 one to the magnetic field 52 the encoder wheel 26 same magnetic field 52 excite and so a speed 12 can simulate. Because the test current 46 in a known manner in the test conductor 48 can be entered is the simulated speed 12 known in advance, so that the regulator 18 can check if this simulated speed 12 from the output signal 40 can be read out. If this is not the case, the regulator could 18 then start a corresponding error program to respond to these errors.

In the same way could also the signal conditioning circuit 38 Perform the above procedure and check if the simulated speed 12 from the speed sensor signal 36 can derive. In case of error, it could then alternatively or additionally to the output signal 40 output a suitable error signal. This would be particularly advantageous if the output signal 40 from the speed sensor 10 next to the regulator 18 is also still used by other institutions, which then would not have to do each for a redundant troubleshooting.

In the present embodiment, the sensor is 50 on a passivation layer 54 the signal conditioning circuit 38 trained so that the test leader 48 directly below the sensor 28 can be arranged.

It will be on the 4a and 4b Reference is made to the reading head 28 of the speed sensor 1 with an alternative test current conductor 48 in a side view and the reading head 28 of the 4a with the test current conductor in a side view.

In the 4 is a sensor 50 with in the signal conditioning circuit 38 integrated. Here is the test leader 48 also next to the sensor 50 be arranged such that the magnetic field 52 still from the sensor 50 can be detected.

Because the sensor 50 and the test leader 48 regardless of the design can be placed locally very close together, the magnetic field 52 and thus the test current 46 be trained very small.

It will be on the 5a and 5b Reference is made to the reading head 28 of the speed sensor 1 with a still alternative test current conductor 48 in a side view and the reading head 28 of the 5a with the test current conductor in a side view.

In the 5a and 5b is the reading head 28 as known per se, the speed 12 formed via a differential field measuring read head. The test leader 48 is in this embodiment U-shaped on the evaluation circuit 54 relocated, taking the individual sensors 50 on the thighs of the U-shaped test lead 48 to be ordered. In this way, the difference field can be used with a single test lead 48 be simulated.

In 6 is a circuit 56 for energizing the test current conductor 48 of the 3a to 5b shown.

The circuit 56 is in the present embodiment to a supply line 58 a current source in the present embodiment 60 connected electrical power source connected. The power source 60 gives a supply current 62 starting from the above reading head 28 supplied with electrical energy. The circuit 56 can alternatively also to a return line 64 to this power source 60 be connected.

In the present embodiment, the circuit 56 a closer 66 on top of the circuit 56 parallel to the supply line 58 followed. This NO contact 66 can from one the sensor 50 testing device, such as the regulator 18 or the signal conditioning circuit 38 be controlled. Will the NO contact 66 closed, part of the supply current flows 62 through the test current conductor 48 as a test current 46 and thus generates the above-mentioned magnetic field 52 ,

To the test current 48 can amplify further after closing the closer 66 one parallel to the circuit 56 switched opener 68 be opened so that the entire supply current 62 as a test current 46 through the test ladder 48 flows. In this way, with the supply current 62 a maximum possible magnetic field 52 being constructed.

In 7 is in a training circuit 56 shown.

In 7 will the circuit 56 as of two in 6 shown terminals 70 . 72 indicated from the beginning. Optionally, the opener 65 as well as to circuit 56 belonging or not belonging to it.

In 7 the circuit has two switches 74 on, over a common control signal 76 be driven, for example, from the sensor 50 testing device, such as the regulator 18 or the signal conditioning circuit 38 can be issued. With the synchronously controlled switches 74 can the test current 46 be designed as alternating current, which is at the speed 12 rotating encoder wheel 26 simulated.

The sensor 50 or the read head 26 can use any form for the test stream 46 be tested as long as this test current 46 the magnetic field 52 builds. On the applied magnetic field 52 the sensor reacts 50 in a predetermined manner, which can be tested during testing.

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 102011080789 A1 [0002, 0035]
• DE 10146949 A1 [0046]

Claims (10)

Method for testing a function of a speed sensor ( 10 ), which is set up, an output signal ( 36 . 40 ) based on one of a rotating object ( 26 ) delivered physical measuring field with a measuring sensor ( 50 ), comprising: - exciting the sensor ( 50 ) with a physical test field known in its form ( 52 ), and - plausibility of the function of the speed sensor ( 10 ) based on a comparison of the output signal ( 36 . 40 ) and the physical test field ( 52 ). Method according to claim 1, wherein the physical test field ( 52 ) a magnetic field different from the physical measuring field ( 52 ) based on a test stream ( 46 ) is excited. The method of claim 2, wherein the speed sensor ( 10 ) with a supply current ( 62 ) is operated, the test current ( 46 ). The method of claim 3, wherein for exciting the test current ( 46 ) a current path ( 48 ) for the test current ( 46 ) parallel to at least part of a current path ( 58 ) for the supply current ( 62 ) of the speed sensor ( 10 ) is connected. Method according to claim 4, wherein a parallel to the current path ( 48 ) for the test current ( 46 ) switched part of the current path ( 58 ) for the supply current ( 62 ) is interrupted after the current path ( 48 ) for the test current ( 46 ) to the speed sensor ( 10 ) connected. Method according to claim 5, wherein the function of the speed sensor ( 10 ) is checked for plausibility after the parallel to the current path ( 48 ) for the test current ( 46 ) switched part of the current path ( 58 ) for the supply current ( 62 ) of the speed sensor ( 10 ) from the speed sensor ( 10 ) is disconnected. Method according to one of the preceding claims, wherein the physical measuring field is separated from the physical test field ( 52 ) is different and the sensor ( 50 ) with the physical test field ( 50 ) is excited when the physical measuring field is equal to zero. Method according to claim 7, wherein the sensor ( 50 ) with the physical test field ( 52 ) is excited when the output signal ( 36 . 40 ) goes through a zero crossing. Control device ( 18 . 38 ) arranged to perform a method according to any one of the preceding claims. Sensor ( 10 ), in particular wheel speed sensor, comprising a control device ( 38 ) according to claim 9.

Images