DE102020216348A1 - Speed sensor with a multi-level protocol - Google Patents

Abstract

Sensor (1) for detecting relative movements between an encoder (2), with an essentially periodic scale and/or pattern, and the sensor (1), the sensor (1) having at least one sensor element (11, 12) and a signal processing device (13), wherein the signal processing device (13) is designed in such a way that it provides a movement signal (S3, S4) in each case as a function of at least one first and one second sensor element output signal (S1, S2) of the at least one sensor element (11, 12), wherein the signal processing device (13) is designed in such a way that it has at least one switching threshold with regard to the at least first and second sensor element output signal, with a Movement information (S3, S4) is generated, after which the movement information (S3) based on the first sensor element output signal (S1), each weighted, are combined with the movement information (S4) based on the second sensor element output signal (S2), whereby a weighted movement signal (S5) with at least three defined signal levels is generated, after which, depending on the weighted movement signal (S5), a Sensor output signal (S5) is provided by the sensor.

Description

The invention relates to a sensor according to the preamble of claim 1.

The invention is based on the object of proposing a sensor which is relatively inexpensive and/or robust and/or measures precisely and/or which enables relatively high resolution and/or can provide information on the direction of rotation or movement with relatively little circuit complexity.

This object is achieved according to the invention by the sensor according to claim 1.

The sensor is preferably designed in such a way that it detects the angle of rotation or the distance of a relative movement between the encoder and the sensor.

The sensor is preferably designed as a speed sensor and/or rpm sensor and/or angular velocity sensor, in particular as a crankshaft rpm sensor or wheel rpm sensor or transmission rpm sensor or turbocharger rpm sensor.

It is preferred that the at least one sensor element comprises a bridge circuit with at least two half bridges or that the sensor has at least two sensor elements, the at least half bridges or the at least two sensor elements each providing a sensor element output signal which is fed to the signal processing device and the signal processing device being designed in this way is that when the respective sensor element output signal of one of the half-bridges or one of the two sensor elements exceeds or falls below a respective switching threshold, movement information is generated which is taken into account in the generation of the two sensor element movement signals or is decisive for their generation. For this purpose, the signal processing device expediently comprises at least two signal paths.

The sensor elements or half-bridges are preferably designed and/or arranged in the sensor, particularly preferably arranged and aligned within the sensor arrangement relative to the encoder in such a way that the sensor element output signals of the at least two sensor elements or half-bridges essentially have a sinusoidal or cosinusoidal time profile have, very particularly preferably with a phase shift of substantially 90 ° to each other.

The at least one sensor element is preferably designed as a magnetic field sensor element, in particular as an AMR, i.e. as anisotropic magnetoresistive, or Hall or GMR, i.e. as giant magnetoresistive or sensor element based on the giant magnetoresistance principle, or TMR sensor element, i.e. as tunnel magnetoresistive sensor element .

The encoder, with an essentially periodic scale and/or pattern, is preferably embodied as a permanently magnetized encoder, in particular having circumferentially alternately magnetized pool pairs, or alternatively preferably as a ferromagnetic gearwheel encoder.

The signal processing device is preferably designed in such a way that each switching threshold includes a hysteresis.

A signal processing device is preferably understood to mean a signal processing circuit and/or a freely programmable circuit.

The signal processing device preferably includes a microcontroller or an electronic circuit with defined or established logic and/or signal processing processes, which performs at least some or all of the calculations and/or signal generation and/or adjustments to the threshold values of the switching thresholds and is designed accordingly.

The signal processing device is preferably designed in such a way that the weighted movement signal is provided by the sensor as a sensor output signal.

The sensor expediently has a plastic housing and two connections as an interface for connection to an electronic control unit of a motor vehicle control or regulation system. The sensor is designed in particular as an active sensor and is supplied with electrical energy via this interface.

It is preferred that the direction of rotation of the encoder detected by the sensor is coded as direction of rotation information in the weighted motion signal and the weighted motion signal has at least three, in particular four, defined signal levels. The direction of rotation information is particularly preferably encoded in the change between the signal levels of the weighted motion signal.

It is expedient for the signal processing device to be designed in such a way that it has two or more switching thresholds with regard to the low has at least one sensor element output signal, with movement information being generated essentially when the respective sensor element output signal exceeds and/or falls below each switching threshold, which is taken into account when generating a sensor element movement signal as a function of each sensor element output signal, after which weighted combination and/or superimposition of the both sensor element movement signals the weighted movement signal (S5) is generated. This provides more signal level changes in terms of more combined motion signals, particularly with increased resolution.

The sensor is preferably designed as a speed sensor, in particular as a wheel speed sensor.

It is preferred that the signal processing device is designed in such a way that the weighted movement signal and/or the sensor output signal is designed as a current signal.

It is preferred that the signal processing device is designed in such a way that the weighted movement signal is generated in such a way that one of the two sensor element movement signals with a substantially double signal level and the other of the sensor element movement signals with a single signal level are superimposed and/or combined to generate the weighted movement signal.

It is preferred that the duration of a signal section of a sensor element movement signal associated with movement information, in particular with a substantially defined signal level, is directly and in particular exclusively dependent on the speed of the relative movement between encoder and sensor.

The signal processing device is preferably designed in such a way that it does not independently evaluate the speed/rotational speed between encoder and sensor.

It is preferred that the signal processing device is designed in such a way that it does not independently evaluate the direction of rotation/direction of movement of the encoder relative to the sensor.

It is expedient for the signal processing device to provide and/or process an additional signal, in particular with a defined signal level and/or a defined temporal signal signal curve and/or signal duration, with this additional signal being superimposed/combined in addition to the sensor element movement signals to generate the weighted movement signal.

The sensor is preferably designed in such a way that it is suitable for detecting rotary movements and/or linear movements of the encoder relative to the sensor.

The sensor preferably includes a sensor element with at least two half bridges that generate the first and the second sensor element output signal. Alternatively, the sensor comprises at least a first and a second sensor element, which generate the first and the second sensor element output signal

The signal processing device is preferably designed in such a way that there is no time coding or no defined fixed time duration of the movement information or of the signal section/signal interval assigned to each movement information with a defined level.

One signal level is preferably understood to mean a signal value and/or an amplitude or an amplitude value.

A direction of rotation is preferably understood to mean a direction of movement. The direction of movement is understood to mean, in particular, the relative direction of movement between encoder and sensor.

The sensor element output signal is preferably the output signal of the sensor element itself or a square-wave signal generated directly therefrom or essentially a square-wave signal, in particular generated by means of at least one amplifier circuit and/or Schmitt trigger circuit.

The sensor preferably has the advantage or the property that the higher the speed or the faster the relative movement between the sensor and the encoder, the faster the levels or level changes occur in the signal processing device.

Advantageously, no decoding of the length of time of the movement signals is required in a control unit to which the sensor is connected. Advantageously, the protocol does not structurally limit the speed of the relative movement between encoder and sensor. The sensor is advantageously suitable for high-resolution detection of the movement or speed between the encoder and the sensor and is at the same time suitable for always providing information about the direction of rotation or information about the direction of movement of the encoder.

The sensor output signal is expediently a current signal, in particular with an impressed current, or alternatively preferably a voltage signal.

A control unit or an electronic control unit or an ECU connected to the sensor preferably decodes information about the direction of rotation and information about speed from the sensor output signal, in particular with regard to each level change in the sensor output signal.

• 1 ein Ausführungsbeispiel des Sensors, welcher an ein Steuergerät angeschlossen ist,
• 2 und 3 beispielhafte Signalverläufe des Sensors.

It show in schematic representation

• 1 an embodiment of the sensor, which is connected to a control unit,
• 2 and 3 example signal curves of the sensor.

Based on 1 a sensor 1 is illustrated, the sensor element half bridges 11 and 12 of which each detect the magnetic field of the alternating, permanent-magnetic encoder 2 and thus detect the relative movement between the encoder 2 and the sensor 1 and the direction of rotation of the encoder 2 . The sensor element output signals S1, S2 of the two sensor element half bridges 11 and 12 are provided to the signal processing device 13. The signal processing device 13 is designed, for example, in such a way that it has at least one switching threshold with regard to the at least first and second sensor element output signal, with movement information essentially being generated when the respective sensor element output signal S1, S2 exceeds and/or falls below the at least one switching threshold after which the movement information based on the first sensor element output signal S1 is weighted and combined with the movement information S4 based on the second sensor element output signal S2, whereby a weighted movement signal S5 with at least three defined signal levels is generated, which is provided as a sensor output signal from sensor 1 to ECU 3 . In terms of its signal form and the signal level changes, this sensor output signal is directly dependent on the relative movement between encoder 2 and sensor 1 and, for example, has no signal components which have a uniformly defined, fixed duration. Signal processing device 13 is designed in such a way that it does not independently evaluate the speed/rotational speed between encoder 2 and sensor 1, nor does it independently evaluate the direction of rotation/direction of movement of encoder 2 relative to sensor 1. This evaluation takes place exclusively in the ECU, which means that the Circuitry and the signal processing complexity in the sensor is relatively low.

2 FIG. 1 shows an exemplary embodiment of the time profiles of the sensor element movement signals S3, S4, with regard to a) and b) in the two opposite directions. The sensor element movement signals S3, S4 are now combined in a weighted manner, specifically the signal level of S4 is weighted twice as heavily as that of S3. S5, as a weighted motion signal with four defined signal levels 0, 1, 2, 3, for example, essentially corresponds to 2 times S4+S3. Weighted motion signal S5 now has information about the direction of rotation between the encoder and sensor, as well as information about the speed of the encoder or the relative speed of motion information between the encoder and sensor.

Based on 3 an exemplary embodiment is illustrated in which, in addition to the two sensor element movement signals S3, S4, an additional signal Z with a defined signal level and a defined signal curve over time is taken into account. Error information from the sensor is encoded in this additional signal, for example. In order to generate the weighted motion signal S5, 3 this additional signal Z is superimposed or combined in addition to the sensor element movement signals S3, S4, with the signal level of S4 also being weighted twice as heavily as that of S3. The signal level of the weighted motion signal S5 is now essentially S3+2 times S4+Z. Regarding 3 a) and b) the signal curves with regard to the two opposite directions of rotation or movement of the encoder are also illustrated.

So example signal levels are possible:

Claims (12)

Sensor (1) for detecting relative movements between an encoder (2), with an essentially periodic scale and/or pattern, and the sensor (1), the sensor (1) having at least one sensor element (11, 12) and a signal processing device (13), the signal processing device (13) being designed in such a way that it is dependent on at least one first and one second sensor element output signal (S1, S2) of the at least one sensor element (11, 12). provides a movement signal (S3, S4), characterized in that the signal processing device (13) is designed in such a way that it has at least one switching threshold with regard to the at least first and second sensor element output signal, wherein essentially in each case when the movement information (S3, S4) is generated by the respective sensor element output signal (S1, S2), after which the movement information (S3) based on the first sensor element output signal (S1) is weighted with the movement information (S4) based on the second sensor element output signal ( S2) be combined, wodu rch a weighted motion signal (S5) is generated with at least three defined signal levels, after which a sensor output signal (S5) is provided by the sensor as a function of the weighted motion signal (S5). Sensor (1) after claim 1 , characterized in that the signal processing device (13) is designed such that the weighted movement signal (S5) is provided as a sensor output signal from the sensor. Sensor (1) according to at least one of the preceding claims, characterized in that the direction of rotation of the encoder (2) detected by the sensor (1) is coded as direction of rotation information in the weighted movement signal (S5), and the weighted movement signal (S5) has at least three , In particular four, has defined signal levels. Sensor (1) after claim 3 , characterized in that the direction of rotation information is encoded in the change between the signal levels of the weighted motion signal (S5). Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) is designed in such a way that it has two or more switching thresholds with regard to the at least one sensor element output signal (S1, S2), with essentially in each case in the case of overshoot and /or if the respective sensor element output signal (S1, S2) falls below each switching threshold, movement information is generated which is taken into account when generating a sensor element movement signal (S3, S4) as a function of each sensor element output signal (S1, S2), after which weighted combination and/or Superposition of the two sensor element movement signals (S3, S4) the weighted movement signal (S5) is generated. Sensor (1) according to at least one of the preceding claims, characterized in that the sensor is designed as a speed sensor, in particular as a wheel speed sensor. Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) is designed in such a way that the weighted movement signal (S5) and/or the sensor output signal is designed as a current signal. Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) is designed in such a way that the weighted movement signal (S5) is generated in such a way that one of the two sensor element movement signals has essentially twice the signal level and the other of the sensor element movement signals are superimposed with a simple signal level and/or combined to generate the weighted motion signal (S5). Sensor (1) according to at least one of the preceding claims, characterized in that the duration (t1) of a signal section of a sensor element movement signal associated with movement information, in particular with a substantially defined signal level, is directly and in particular exclusively dependent on the speed of the relative movement between the encoder ( 2) and sensor (1). Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) is designed in such a way that it does not independently evaluate the speed/rotational speed between encoder (2) and sensor (1). Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) is designed so that it does not independently evaluate the direction of rotation/direction of movement of the encoder (2) relative to the sensor (1). Sensor (1) according to at least one of the preceding claims, characterized in that the signal processing device (13) provides an additional signal (Z), in particular with a defined signal level and/or defined signal signal curve over time and/or signal duration and/or processed, this additional signal (Z) being superimposed/combined in addition to the sensor element movement signals (S3, S4) to generate the weighted movement signal (S5).

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