DE102019216418A1 - Measuring device for a wheel and method for determining a rotational speed - Google Patents

Abstract

The proposed solution relates in particular to a measuring device for determining a rotational speed of a wheel (11, 12) rotatable about an axis of rotation (D) on a vehicle (1), with at least one detection device (14) for generating measurement signals with which a Rotational speed of the wheel (11, 12) can be determined, and a first signal transmitter (30, 33) provided on the wheel (11, 12) with which when the wheel (11, 12) rotates about the axis of rotation (D) and an accompanying movement of the signal transmitter (30, 33) relative to the detection device (14), at least one measurement signal can be generated on the detection device (14). At least one second signal transmitter (31, 34) and at least one third signal transmitter (32, 35) are also provided on the wheel (11, 12), the second signal transmitter (31, 34) along a circumferential direction around the axis of rotation (D) to the first signal transmitter (30, 33) at a first distance (φ1, ψ1; φ3, ψ3 ) is arranged and the third Signal transmitter (32, 35) along the circumferential direction to the second signal transmitter (31, 34) at a second distance (φ2, ψ2; φ4, ψ4) is arranged, which is different from the first distance (φ1, ψ1; φ3, ψ3).

Description

The proposed solution relates in particular to a measuring device for determining a rotational speed of a wheel rotatable about an axis of rotation.

For example from the DE 10 2017 212 92 A1 It is known to provide a measuring device for determining a rotational speed of a wheel, in particular a wheel for a two-wheeled vehicle, in which at least one detection device for the generation of measurement signals is combined with a signal transmitter provided on the wheel, which with a rotation of the wheel around the Axis of rotation and an accompanying movement of the signal generator relative to the detection device generates at least one measurement signal on the detection device.

A corresponding signal transmitter has, for example, a magnet and the detection device has a magnetic sensor. In this way, by moving the magnet past the magnetic sensor, a sharply defined measurement signal can be generated when the magnet passes through the rotation of the wheel of the magnetic sensor. In order to then determine a rotational speed of the wheel, at least two complete revolutions and thus passages of the magnet past the magnetic sensor must be detected. Knowing the wheel circumference of the wheel, the speed of a vehicle with the wheel, e.g. a two-wheeler, can then be determined from the rotational speed of the wheel.

For a supposedly faster detection of the speed of rotation of the wheel, the beats DE 10 2017 212 924 A1 propose to provide two magnets on the wheel. In this way, at least two pieces of speed information can be obtained with each revolution of the wheel. A time interval between two points in time at which the two magnets pass the detection device with the magnetic sensor can also be taken into account here. However, the possibilities for plausibility checking and validation of detectable measurement signals are very limited even with such a configuration, so that additional and comparatively complex measures may have to be taken to prevent further functions on the vehicle from being controlled on the basis of incorrect measurement signals from the detection device.

Against this background, the proposed solution is based on the object of providing an improved measuring device and an improved method for determining a rotational speed of a wheel that can be rotated about an axis of rotation.

This object is achieved both with a measuring device of claim 1 and with a method of claim 14.

The proposed solution provides, in particular, a measuring device for determining a rotational speed of a wheel on a vehicle that is rotatable about an axis of rotation, the measuring device having at least one (electronic) detection device for generating measurement signals with which a rotational speed of the wheel can be determined. Furthermore, the first, second and third signal transmitters provided on the wheel are part of the measuring device, with which at least one measurement signal can be generated at the detection device when the wheel rotates around the axis of rotation and the signal transmitter moves with it relative to the detection device. Of the at least three signal generators, the second signal generator is arranged along a circumferential direction around the axis of rotation to the first signal generator at a first distance, while the third signal generator is arranged along the circumferential direction to the second signal generator at a second distance, which is the first distance between the first and second signal generators is different.

According to the proposed solution, at least three signal transmitters, which are spaced differently from one another, are consequently arranged on the wheel which is rotatable relative to a component of the vehicle carrying the detection devices. With the different spacing of the signal generators from one another, additional possibilities for signal processing are associated. Thus, when the wheel rotates, measurement signals that follow one another over time are generated in a characteristic sequence / sequence via signal transmitters at different distances from one another. In this way, not only can a plausibility check of the recorded measurement signals take place electronically, but a direction of rotation of the wheel can also be determined comparatively easily. For example, at least three signal transmitters on a detection device arranged immovably on the vehicle generate a characteristic sequence of measurement signals following one another in time when these are guided past the detection device, a sequence generated depending on the direction of rotation of the wheel due to the different distances between the first and second Signal transmitters as well as between the second and third signal transmitters and thus a sequence for the respective direction of rotation is unique:

Furthermore, the use of signal transmitters that are not equidistantly spaced from one another allows a more rapid determination of a rotational speed of the wheel. One full turn of the wheel is thus not necessary to reliably infer the current speed of rotation of the wheel.

In one embodiment, an (electronic) evaluation logic is provided which is configured to determine a rotational speed of the wheel on the basis of a first measurement signal for the first signal transmitter, a second measurement signal for the second signal transmitter and a third measurement signal for the third signal transmitter as well as the first and second distances is. The first and second distances can be stored and stored as constants in a calculation rule implemented by the electronic evaluation logic. The first and second distances can be learned and stored in particular in a learning phase of the measuring device. Alternatively or in addition, the first and second distances can be stored as fixed constants in a memory of the measuring device, which the evaluation logic can access. According to the known physical relationships between distance, time and speed, an evaluation logic of the measuring device is able to determine a rotational speed of the wheel on the basis of the first, second and third measurement signals, in particular on the basis of the times at which these measurement signals are generated determine.

In this context, one embodiment variant provides, for example, that the evaluation logic is configured to generate a first speed value for the rotational speed of the wheel from a) a first time difference between a second (measurement) point in time for the second measurement signal (i.e. a point in time at which the second Measurement signal is generated) and a first time for the first measurement signal and b) to determine the first distance and also a second speed value for the rotational speed of the wheel from c) a second time difference between a third time for the third measurement signal and the second time for the second measurement signal and b) the second distance. Due to the different intervals between the first, second and third timers, the recorded (measuring) times can be clearly assigned to the individual first, second and third signal transmitters. The respective times for a generated measurement signal can thus easily be set in relation to the respective distances in order to use this to calculate a speed value for the rotational speed of the wheel

In the first and second speed values for the rotational speed of the wheel are available on the basis of the embodiment variant explained above, the evaluation logic can be configured to generate a speed signal representative of the rotational speed of the wheel on the basis of the first determined speed value and the second determined speed value. A speed signal representative of the rotational speed of the wheel can consequently be based on both first and second determined speed values. This includes, for example, that only one of the speed values is used for a plausibility check of the other speed value and one of the speed values becomes the basis for the speed signal. Alternatively, a representative final speed value, which is the basis for the speed signal, can be calculated from the first and second speed values. For example, a mean value of the first and second speed values is transmitted as the rotational speed of the wheel with the speed signal.

In order to increase the measuring certainty and the reliability of the measuring device and in particular a speed signal that is generated with it and is representative of the rotational speed of the wheel, an embodiment variant can provide that a speed signal is only generated under the condition that it was previously checked whether the at least three Signal transducers generated first, second and third measurement signals and the (measurement) points in time given hereby actually originate from the signal transducers when the wheel rotates. The first and second speed values determined are therefore only used to generate a speed signal, for example, after it has been checked that the first, second and third measurement signals generated with the aid of the at least three signal transmitters and the (measurement) points in time during a rotation are predetermined of the wheel actually come from the signaling devices.

As an alternative or in addition, the first and second speed values can only be used if it has been checked with the aid of the evaluation logic that they do not differ from one another by more than a predetermined tolerance threshold. This rules out, for example, that a measurement was incorrect and / or that a significant (positive or negative) acceleration of the wheel has just occurred between two measurement signals, so that the first and second calculated speed values differ (too) from one another.

In one embodiment variant, when the wheel rotates, a characteristic sequence of chronologically successive measurement signals can be generated on the detection device via the first, second and third signal transmitters arranged at different first and second distances from one another on the wheel. This, in particular, depending on Direction of rotation of the wheel, characteristic sequence can be based solely on the different distances between the first, second and third signal transmitters and thus the non-equidistant arrangement of the signal transmitters on the wheel. Alternatively or in addition, the characteristic sequence can also be based on a unique identifier assigned to each signal transmitter, so that a measurement signal generated with the aid of a signal transmitter can be clearly assigned to a specific signal transmitter of the first, second and third signal transmitters. The electronic detection device thus detects an identification parameter that is unique for each signal transmitter, such as an identification number, for example when a signal transmitter is guided past the detection device by turning the wheel.

In one embodiment variant, in which the characteristic sequence is taken into account with the aid of the different distances between the first, second and third signal generators, in particular is recognized based on this alone, it is provided, for example, that chronologically successive measurement signals can be generated at chronologically successive first, second and third points in time and an (electronic) evaluation logic is provided which is configured to recognize that the characteristic sequence has been generated, the first, second and third points in time at which measurement signals were generated by the first, second and third signal transmitters in relation to the first and second intervals. The evaluation logic is therefore configured to at least temporarily store time stamps for the first, second and third points in time and to allow them to flow into a calculation in which the first and second intervals are also included as parameters (already stored in advance).

In an embodiment variant based on this, the evaluation logic is then configured, for example, to recognize the characteristic sequence, to form a first time difference from the first and second points in time and a second time difference from the second and third points in time, and a ratio of the first and second time differences with a calculated one Compare the ratio of the first and second distances. Assuming constant or at least approximately constant rotational speed of the wheel, a calculated ratio between the first and second time differences is identical to a stored or calculated ratio of the first and second distances between the signal transmitters. In this way, with comparatively little sensor and computational effort, a variant of the proposed measuring device can be used to check whether there are actually plausible measured values (and in particular from the correct signal transmitters) before a speed signal representative of the rotational speed of the wheel is made available, in particular before one Speed signal is calculated in the first place.

For example, an evaluation logic of the measuring device can be configured to determine a rotational speed of the wheel only when the generation of the characteristic sequence has been detected electronically with the aid of the detection device. A speed of rotation of the wheel is only calculated, for example, when sufficient correspondence has been established between a ratio of the first and second time differences and a ratio of the first and second intervals. For example, it is then first checked whether the two ratios are identical to one another or at least only differ from one another by a defined tolerance value.

In one embodiment, an evaluation logic of the measuring device can be configured, based on a first measuring signal for the first signal transmitter and a third measuring signal for the third signal transmitter and a third distance along the circumferential direction between the first signal transmitter and the third signal transmitter, a plausibility check for a using measurement signals the first, second and third signal generator to perform determined rotational speed of the wheel. In this variant, a third, stored distance, measured along the circumferential direction, between the first signal transmitter and the third signal transmitter is consequently taken into account in order to additionally check a determined rotational speed for plausibility. In this case, the evaluation logic is then configured, for example, to check whether a combination of a) a rotational speed determined using first, second and third measurement signals and the first and second intervals and b) first and third points in time at which the first and third measurement signals generated (or a time difference from the third and first points in time) results in a distance value which corresponds to the stored third distance (possibly plus an allowed tolerance). In this variant, a supposed rotational speed of the wheel is multiplied by a time difference in order to calculate a distance value from this, which can then be compared with a stored value for the third distance between the first and third signal transmitter on the wheel. If no deviations, or at most only minor deviations, i.e. within specified tolerances, are determined, it can be assumed that the previously determined value for the rotational speed is plausible.

The first and second distances between the signal generators are basically variable. In one embodiment variant is for example with a view to a simpler plausibility check is provided that a distance is a multiple, in particular an integer multiple, of another distance. In other words, the first distance is then, for example, a multiple of the second distance or, conversely, the second distance is a multiple of the first distance.

In one embodiment variant, at least two groups, each with first, second and third signal transmitters, are provided on the wheel. In this embodiment variant, at least two (signal generator) groups, each with at least three signal generators, are consequently provided on the wheel, in which, within a group of signal generators, a distance between first and second signal generators differs from a distance between second and third signal generators. In this way, for example, two characteristic, possibly different sequences for the two groups can also be recognized via a single electronic detection device. By using two groups, it is not only possible to determine a rotational speed on the wheel, for example with half a revolution, but also with just one full revolution of the wheel in several ways to check the plausibility of a determined rotational speed and to correct the rotational speed at least once or again to calculate.

In principle, the electronic generation of the measurement signals can take place, for example, with the aid of a magnetically, optically, capacitively or inductively actuated, optionally measuring sensor of the detection device. A magnetically actuated sensor includes, for example, a reed contact, on which magnets of the first, second and / or third signal transducers pass when the wheel rotates and then each lead to the closing of an electrical contact, which in turn generates the respective first, second or third measurement signal , here, for example, like a pulse signal.

Alternatively, the electronic detection device can comprise an optical sensor, so that at least one of the first, second and third signal transmitters influences a light beam generated by the detection device in order to generate a respective first, second or third measurement signal. For example, the detection device can comprise a light barrier and a signal transmitter can have a perforated plate or a reflector, which causes a sensor-detectable influence on the light beam generated by the detection device when the signal transmitter is moved past the detection device when the wheel is rotated.

The proposed measuring device can be used in particular in a two-wheeler, for example in an electric bicycle.

For example, it is known to provide a pushing aid via an electric motor drive of an electric bicycle, i.e. an electric motor drive of a so-called e-bike or pedelec, in order to support a user when pushing the electric bike or when starting off, for example on an incline. The maximum speed provided by the pushing aid for the electric bike is regularly limited by law. Usually a speed of 3 km / h to 6 km / h is reached with a pushing aid. In order not to accelerate the electric bicycle excessively via the electric motor drive, a speed control is provided with which the electric motor drive is actuated on the basis of at least one electronically recorded speed signal. For this purpose, for example, a measuring device is provided for a wheel of the bicycle in order to provide a speed signal that is representative of the rotational speed of the wheel and thus a speed signal that is representative of the driving speed of the electric bicycle and that forms the basis for regulating the electric motor drive of the electric bicycle. Such a speed signal can be provided with a variant embodiment of a proposed measuring device in a particularly simple manner and with less than one rotation of the wheel.

The proposed solution also relates to a method for determining a rotational speed of a wheel on a vehicle that is rotatable about an axis of rotation.

• - mit mindestens einer Erfassungseinrichtung Messsignale erzeugt werden, mit denen eine Drehgeschwindigkeit des Rades ermittelbar ist, und
• - mit an dem Rad vorgesehenen ersten, zweiten und dritten Signalgebern erste, zweite und dritte Messsignale an der Erfassungseinrichtung erzeugt werden, wenn das Rad um die Drehachse gedreht und hierdurch die Signalgeber relativ zu der Erfassungseinrichtung verlagert werden.

The proposed procedure provides that

• - Measurement signals are generated with at least one detection device with which a rotational speed of the wheel can be determined, and
• - With first, second and third signal transmitters provided on the wheel, first, second and third measurement signals are generated on the detection device when the wheel is rotated about the axis of rotation and the signal transmitters are thereby displaced relative to the detection device.

The measurement signals of the at least three signal transmitters are used to determine the rotational speed of the wheel, the second signal transmitter being arranged along a circumferential direction around the axis of rotation to the first signal transmitter at a first distance and the third signal transmitter along the circumferential direction to the second signal transmitter in one second distance is arranged, which is different from the first distance (between the first and second signal generators).

Typically, the detection device is arranged immovably on the vehicle and is provided on a component of the vehicle, relative to which the wheel is rotatable. The signal transmitters are then guided past a sensor of the electronic detection device, for example, in order to generate the first, second and third measurement signals.

A proposed measuring device is particularly suitable for carrying out an embodiment of the proposed method. Advantages and features of design variants of a proposed measuring device explained above and below therefore also apply to design variants of a proposed method and vice versa.

In particular, an embodiment variant of a proposed method can accordingly provide, for example, that the first, second and third signal transmitters generate a characteristic sequence of chronologically successive measurement signals at the detection device when the wheel rotates.

Likewise, alternatively or additionally, provision can be made, for example, that first and second speed values are determined on the basis of first and second time differences and stored first and second intervals in order to generate a speed signal representative of the rotational speed of the wheel.

As already explained above in connection with an embodiment variant of a proposed measuring device, alternatively or additionally in an embodiment variant of the proposed method it can be provided that a plausibility check for a determined rotational speed is based on first and third measurement signals and a third distance between the first and third signal transmitter of the wheel is carried out.

The attached figures illustrate possible variants of the proposed solution by way of example.

• 1 ausschnittsweise eine erste Ausführungsvariante einer vorgeschlagenen Messvorrichtung, mit drei Signalgebern, die an Speichen eines Rades angeordnet sind;
• 2 ein Flussdiagramm für ein Ausführungsbeispiel eines vorgeschlagenen Verfahrens zur Ermittlung einer Drehgeschwindigkeit mithilfe einer Messvorrichtung der 1;
• 3A-3B in mit der 1 übereinstimmender Ansicht zwei weitere Ausführungsvarianten einer vorgeschlagenen Messvorrichtung, die jeweils zwei Gruppen von jeweils drei Signalgebern an den Speichen des Rades umfasst;
• 4 schematisch ein Elektrofahrrad in Seitenansicht, das eine Ausführungsvariante einer vorgeschlagenen Messvorrichtung aufweist.

Here show:

• 1 a section of a first variant of a proposed measuring device, with three signal transmitters, which are arranged on the spokes of a wheel;
• 2 a flowchart for an embodiment of a proposed method for determining a rotational speed with the aid of a measuring device from FIG 1 ;
• 3A-3B in with the 1 matching view, two further design variants of a proposed measuring device, each comprising two groups of three signal transmitters on the spokes of the wheel;
• 4th schematically an electric bicycle in side view, which has an embodiment variant of a proposed measuring device.

The 4th shows schematically and in side view an electric bicycle 1 . This electric bike 1 includes a frame 10 , a front wheel 11 and a rear wheel 12th . On the frame 10 is a driving device A. provided with at least one electric motor drive to a power transmission member 13th , for example in the form of a chain or a belt 13th , a driving force generated by the drive motor on the rear wheel 12th for driving the electric bike 1 transferred to. A speed of the electromotive drive of the drive device A. and / or a bottom bracket shaft driven by the drive motor is via a motor sensor 15th supervised. The drive device is controlled A. via control electronics SE . This control electronics SE is with a control unit 2 on a steering wheel of the electric bike 1 controllable.

The control electronics SE is equipped with a detection device in the form of a wheel sensor 14th coupled. In the in the 4th The embodiment variant shown as an example is the wheel sensor 14th frame fixed in the area of the rear wheel 12th intended. Alternatively or in addition, a corresponding wheel sensor can be used 14th on the front wheel 11 be provided. About the wheel sensor 14th becomes the control electronics SE a speed signal is provided which is representative of the rotational speed of the rear wheel 12th and thus for the current driving speed of the electric bike 1 . A corresponding speed signal is used here, for example, for speed control of a pushing aid of the electric bicycle 1 used.

To about the wheel sensor 14th already with a full turn of the rear wheel 12th or even a fraction of a full turn of the rear wheel 12th The wheel sensor is capable of delivering a reliable speed signal 14th Part of a proposed measuring device and also, for the implementation, an embodiment variant of a proposed method for determining a rotational speed of the rear wheel 12th intended.

In a first embodiment according to the 1 are for this on spokes 120 of the rear wheel 12th three signal transmitters in the form of magnets 30th , 31 and 32 arranged. The one around an axis of rotation D. rotatable wheel 12th provided magnets 30th , 31 and 32 represent the first, second and third signal transmitters of the measuring device, which are activated when the rear wheel rotates 12th around the axis of rotation D. on that firmly on the frame 10 fixed wheel sensor 14th be led by. When passing a magnet 30th , 31 or 32 on the wheel sensor 14th a measurement signal is generated. For example, the wheel sensor includes 14th for this purpose a reed contact, so that by passing a magnet 30th , 31 or 32 an electrical pulse is generated as a measurement signal.

Along a circumferential direction around the axis of rotation D. are the three magnets 30th , 31 and 32 non-equidistantly spaced from one another. Rather, there is a first distance between a first magnet 30th and a second magnet 31 smaller than a distance between the second magnet 31 and the third magnet following in the circumferential direction 32 . The different distances are in the 1 due to two different sized spacing angles φ ₁ and φ ₂ represents. The size of a clearance angle φ ₁ or φ ₁ correlates here with the different distances between the respective magnets 30th / 31 and 31 / 32 . The present example is the larger spacing angle φ ₁ between the second magnet 31 and the third magnet 32 many times larger than the distance angle φ ₁ between the first magnet 30th and the second magnet 31 .

About along the circumferential direction around the axis of rotation D. mutually differently spaced magnets 30th , 31 and 32 becomes when the rear wheel rotates 12th around the axis of rotation D. on the wheel sensor 14th generates a characteristic sequence of successive measurement signals. Is a rotational speed of the rear wheel 12th around the axis of rotation D. constant, or at least largely constant, are made by the magnets 30th , 31 and 32 generated measurement signals at the wheel sensor 14th generated at time intervals correlating with the intervals. In this way, on the basis of the sequence of the recorded measurement signals, it is possible in particular to infer in which of two possible directions of rotation s1 , s2 around the axis of rotation D. the rear wheel 12th is rotated. In addition, the recorded measurement signals allow after a fraction of a full revolution of the rear wheel 12th a reliable and, in particular, plausibility checkable determination of a rotational speed of the rear wheel 12th and from this a travel speed of the electric bicycle 1 .

$$2.{\text{ s}}_{\mathrm{\phi 2}}=\text{v}*\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right)\text{ --> }\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right)={\text{s}}_{\mathrm{\phi 2}}/\text{v},$$

$$3.{\text{ s}}_{\mathrm{\phi 3}}=\text{v}*\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{30}}\right)\text{ --> }\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{30}}\right)={\text{s}}_{\mathrm{\phi 3}}/\text{v},$$

For the evaluation of the on the wheel sensor 14th detected measurement signals are taken into account, for example, that for a rotational speed v of the rear wheel assumed to be constant 12th during one of the forward travel of the electric bike 1 corresponding rotation around the axis of rotation D. in direction of rotation s1 the following relationships apply: $$1.{\text{s}}_{\mathrm{\phi 1}}=\text{v}*\left({\text{t}}_{\text{31}}-{\text{t}}_{\text{30th}}\right)\text{->}\left({\text{t}}_{\text{31}}-{\text{t}}_{\text{30th}}\right)={\text{s}}_{\mathrm{\phi 1}}/\text{v},$$

$$2.{\text{s}}_{\mathrm{\phi 2}}=\text{v}*\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right)\text{->}\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right)={\text{s}}_{\mathrm{\phi 2}}/\text{v},$$

$$\mathrm{3rd}{\text{s}}_{\mathrm{\phi 3}}=\text{v}*\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{30th}}\right)\text{->}\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{30th}}\right)={\text{s}}_{\mathrm{\phi 3}}/\text{v},$$

The path lengths s _φ1 , s _φ2 and s _{φ3 correspond to} the distance angles φ ₁ , φ ₂ and (φ ₃ + φ ₁ ) between the magnets 30th , 31 and 32 so that with a known radius r of the rear wheel 12th or a known circumference U (with U = 2Πr) of the wheel 12th for s = _φ1 2Πr * φ _1/360 °, _φ2 = s 2Πr * φ ₂ / s 360 °, and _φ3 = 2Πr * (φ ₁ + φ ₂₎ / 360 °. The times t ₃₀ , t ₃₁ and t ₃₂ correspond to the times at which a measurement signal is sent to the wheel sensor 14th from the first magnet 30th , the second magnet 31 or the third magnet 32 was generated. From the recorded times t ₃₀ , t ₃₁ and t ₃₂ and a time stamp representative of the time at which a respective measurement signal was recorded in a memory of the wheel sensor 14th (and if necessary the control electronics SE ) comprehensive measuring device can thus directly a rotational speed of the rear wheel 12th calculated and thus determined.

gilt, nachdem alle drei Messsignale und damit Zeitstempel einer Sequenz erfasst und die Vollständigkeit der Sequenz erkannt wurde.Before outputting and / or forwarding a determined speed signal, it can first be checked whether the recorded time stamps and the time differences obtained therefrom are valid. For this purpose, for example, a second time difference (t ₃₂ t ₃₁ ) is set in relation to a first time difference (t ₃₁ -t ₃₀ ) and the ratio of these time differences (t ₃₂ -t ₃₁ ) / (t ₃₁ -t ₃₀ ) with a ratio φ ₂ / φ ₁ the distance angle φ ₁ and φ ₂ compared. For example, it is checked accordingly whether $${\text{R.}}_{\text{Seq}}={\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102019216418A1\_0008.png,DE102019216418A1\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_2/{\mathrm{\phi }}_1={\text{s}}_{{\mathrm{<figure-callout\; id="2"\; label="\phi "\; filenames="DE102019216418A1\_0008.png,DE102019216418A1\_0010.png"\; state="\{\{state\}\}">\phi </figure-callout>}}_2}/{\text{s}}_{\mathrm{\phi }1}=\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right)/\left({\text{t}}_{\text{31}}-{\text{t}}_{\text{30th}}\right)$$

applies after all three measurement signals and thus time stamps of a sequence have been recorded and the completeness of the sequence has been recognized.

In one embodiment variant, a plausibility check is also carried out to determine whether one is using the measurement signals from the first, second and third magnets 30th to 32 determined rotational speed v of the rear wheel 12th is actually plausible in the light of the distance relationships. In this case, for example, a distance _value s φ3 * is then used for the distance angle φ ₁ + φ ₂ and thus a distance between the first magnet 30th and the third magnet 32 determined on the basis of the calculated rotational speed and compared to what extent this calculated distance value s _φ3 * with the actual one Distance _value s φ3 coincides. The following applies to the calculated distance value s _{φ3 *:} $${\text{s}}_{\mathrm{\phi 3}}*=\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{30th}}\right)/\text{v}.$$

If the calculated distance value s _φ3 * agrees with the actual, stored distance _value s φ3, possibly plus a specified tolerance, the calculated speed value v is assessed as plausible.

$${\text{v}}_2={\text{s}}_{\mathrm{\phi 2}}/\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right).$$

In a variant embodiment, first and second speed values v ₁ and v ₂ can be set using the time differences (t ₃₁ -t ₃₀ ) and (t ₃₂ -t ₃₁ ) and the distance angle φ ₁ and φ ₂ be calculated. A calculation rule would therefore be as follows, as already shown above: $${\text{v}}_1={\text{s}}_{\mathrm{\phi 1}}/\left({\text{t}}_{\text{31}}-{\text{t}}_{\text{30th}}\right),$$

$${\text{<figure-callout id="2" label="v" filenames="DE102019216418A1\_0008.png,DE102019216418A1\_0010.png" state="{{state}}">v</figure-callout>}}_2={\text{s}}_{\mathrm{\phi 2}}/\left({\text{t}}_{\text{32}}-{\text{t}}_{\text{31}}\right).$$

From these two first and second speed values v ₁ and v ₂ , an averaged rotational speed for the rear wheel could then, for example, by averaging 12th calculated and made available as a speed signal.

The flow chart of the 2 illustrates a possible variant embodiment for one with the measuring device of FIG 1 feasible method for determining a rotational speed v a about an axis of rotation D. rotatable front or rear wheel 11 or 12th .

Initially, activation of the measuring device is provided. This activation can be done, for example, by moving the electric bike, which is initially at rest 1 respectively. The measuring device is then initially still in a state of rest until - depending on the direction of rotation s1 or s2 - a first magnet, for example the magnet 30th when turning in the direction of rotation s1 , on the wheel sensor 14th is passed.

Will be passing the first magnet 30th on the wheel sensor 14th detected without errors, a time stamp for the occurrence of the generated measurement signal is stored. It is then checked whether the characteristic sequence of the successive measurement signals has been completed with the stored time stamp. If this is not the case, the further evaluation ends and the occurrence of a further measurement signal or a further time stamp is first waited for.

On the other hand, it becomes when the wheel rotates 11 or 12th with the detection of a third time stamp (time t ₃₂ ) for the by the third magnet 32 on the wheel sensor 14th If the measurement signal generated completes the sequence, it is then checked whether a speed has already been calculated on the basis of the recorded time stamp. If this is not the case, the sequence is first checked for correctness. In this case, it is only determined whether the recorded sequence of consecutive time stamps or chronologically consecutive measurement signals of a taught-in sequence and thus that on the wheel 11 or 12th predetermined arrangement of magnets 30th , 31 and 32 can correspond. If, during this test, with the aid of the electronic measuring device and in particular its evaluation logic, it has been established that a characteristic sequence has been recorded, the (possibly averaged) rotational speed v of the respective wheel is used 11 or 12th calculated and saved.

The measuring device now specifies a time-out and thus a period of time within which the rotational speed v of the wheel calculated in this way 11 or 12th must be validated and checked for plausibility before this is used as a speed signal for further processing, for example for regulating a pushing aid on the electric bicycle 1 , is made available.

According to the flow chart of 2 a further, fourth time stamp is awaited here, for example a renewed detection of an on the first magnet 30th decreasing measurement signal at the wheel sensor 14th . If this fourth time stamp has been recognized, the previously determined rotational speed v of the wheel is checked 11 or 12th on validity. Here, for example, as explained above, first and second speed _{values v 1} and v ₂ are compared with one another, one or both of which were the basis for the generated speed value v. If the calculated speed v is classified as valid on this basis, a for the rotational speed of the wheel is generated and transmitted 11 or 12th representative speed signal to the control electronics SE .

If the calculated speed v was classified as invalid in the validity check, a manipulation check is carried out on the other hand. As already explained above, the third spacing angle is used for this purpose φ ₁ + φ ₂ between the first magnet 30th and the third magnet 32 or a distance _{value s φ3 is} used and checked to what extent the calculated rotational speed v and that for the first magnet 30th and the third magnet 32 detected time stamps for the times t ₃₀ and t ₃₂ a distance value s _φ3 * can be calculated, which deviates _{from the actual distance value s φ3 by at most a permissible tolerance.} If the latter is the case, it can be assumed, for example, that the measuring device has been manipulated, so that the measuring device subsequently throttles the output via the electromotive drive device A. provided driving force and thus driving speed of the electric bike 1 undertakes. In response to a detected manipulation of the measuring device, however, a further or alternative sanctioning measure can in principle also be triggered, that is to say in addition to or instead of the throttling of the driving force. For example, the electromotive drive device A. be completely deactivated in response to a detected manipulation of the measuring device.

The 3A and 3B show possible developments of the measuring device of 1 . With the design variants of the 3A and 3B is again exemplary for both bikes here 11 and 12th shown rear wheel 12th of the electric bike 1 a single wheel sensor 14th intended to generate the measurement signals and the time stamp. In contrast to the variant of the 1 is, however, in addition to a first signal generator group 3A with first, second and third magnets 30th to 32 a second signal generator group 3B with three more, first, second and third magnets 33 , 34 and 35 intended.

The magnets too 33 to 35 the second signal generator group 3B are non-equidistant from one another along a circumferential direction about the axis of rotation D. spaced from each other. The guiding of the first, second and third magnets also leads accordingly 33 to 35 the second signal generator group 3B on the wheel sensor 14th over to the generation of a characteristic sequence of measurement signals or time stamps.

The signal generator groups 3A and 3B are on the rear wheel shown 12th by a group distance angle α spaced from each other. In other words, it relates to the direction of rotation s1 for forward travel of the electric bike 1 a last, third magnet 32 the first signal generator group 3A around the group distance angle α to the foremost, first magnet 33 the second signal generator group 3B spaced on the rear wheel 12th arranged.

In the variant of the 3A are also the distances between the first magnets 30th / 33 and second magnet 31 / 34 depending on the signal generator group 3A , 3B differently chosen. This is the case with the first signal generator group 3A a distance angle φ ₁ between the first magnet 30th and the second magnet 31 less than a distance angle φ ₂ between the second magnet 31 and the third magnet 32 (possibly with φ ₂ = k * φ ₁ , with k ∈ N). In contrast, the second signal generator group 3B a distance angle φ ₃ between the first magnet 33 and the second magnet 34 greater than a distance angle φ ₄ between the second magnet 34 and the third magnet 35 (whereby the following can also apply here: φ ₃ = I * φ ₄ , with I∈N). Depending on whether the first, second and third magnets 30th to 32 the first signal generator group 3A or the first, second and third magnets 33 to 35 the 2nd signal generator group 3B by turning the rear wheel 12th on the wheel sensor 14th are passed, different, characteristic sequences of chronologically successive measurement signals and thus recorded time stamps are generated. The sequences can thus be distinguished from one another: Furthermore, both signal generator groups 3A , 3B regardless of the direction of rotation of the rear wheel 12th after less than a full turn around the axis of rotation D. be used to generate a speed signal v, since their magnets 30th to 32 or 33 to 35 each (as in the variant of the 1 ) within a circular sector of the rear wheel 12th are placed, which extends only over an angular range of less than 90 °, in particular less than 60 ° and possibly less than 45 °, for example 30 °.

With the variant of the 3 are also two signal generator groups 3A and 3B intended. The signal generator groups 3A , 3B the 3B are at a larger group spacing angle β offset to each other. Furthermore, in contrast to the variant of the 3A first, second and third magnets 30th to 32 and 33 to 35 of the two signal generator groups 3A and 3B although not equidistant within a signal generator group 3A or 3B at a distance from one another, but similar or even identical in groups.

For example, based on a direction of rotation s1 , at the first signal generator group 3A a first magnet 30th by a distance angle ψ ₁ to a second magnet 31 be spaced and at the second signal generator group 3B a first magnet 33 by a distance angle ψ ₃ to a second magnet 34 spaced, which is substantially or exactly the spacing angle ψ ₁ the first signal generator group 3A corresponds to. The same then applies to spacing angles ψ ₂ and ψ ₄ between the second and third magnets 31 / 32 and 34 / 35 of the two signal generator groups 3A , 3B . The 3B shows the possibility of using for several signal generator groups in front of this background 3A , 3B each identical characteristic sequences to work. In this embodiment variant, too, the advantages of a faster and more reliable determination of the rotational speed are retained.

List of reference symbols

1

Electric bike (two-wheeler)

10

frame

11

Front wheel

12th

Rear wheel

120

spoke

13th

Chain / belt (power transmission link)

14th

Wheel sensor (detection device)

15th

Motor sensor

2

Control unit

30-35

Magnet (signal generator)

3A, 3B

Signal generator group

A.

Drive device

D.

Axis of rotation

s1, s2

Direction of rotation

SE

Control electronics

α, β

Group distance angle

φ1 - φ4, ψ1 - ψ4

Distance angle

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 10201721292 A1 [0002]
• DE 102017212924 A1 [0004]

Claims (15)

Measuring device for determining a rotational speed of a wheel (11, 12) rotatable about an axis of rotation (D) on a vehicle (1), with - at least one detection device (14) for generating measurement signals with which a rotational speed of the wheel (11, 12) can be determined, and - a first signal transmitter (30, 33) provided on the wheel (11, 12) with which the signal transmitter moves when the wheel (11, 12) rotates about the axis of rotation (D) (30, 33) relative to the detection device (14) at least one measurement signal can be generated on the detection device (14), characterized in that at least one second signal transmitter (31, 34) and at least one third signal transmitter (32, 35) on the wheel (11, 12) are provided, the second signal transmitter (31, 34) being arranged along a circumferential direction around the axis of rotation (D) to the first signal transmitter (30, 33) at a first distance (φ1, ψ1; φ3, ψ3) and the third signal generator (32, 35) along the circumferential direction to the second signal generator (31, 34) at a second distance (φ2, ψ2; φ4, ψ4) is arranged, which is different from the first distance (φ1, ψ1; φ3, ψ3). Measuring device according to Claim 1 , characterized in that an evaluation logic is provided which is used to determine a rotational speed of the wheel (11, 12) on the basis of a first measurement signal for the first signal transmitter (30, 33), a second measurement signal for the second signal transmitter (31, 34) and a third measurement signal for the third signal generator (32, 35) and the first and second distances (φ1, φ2, ψ1, ψ2; φ3, φ4, ψ3, ψ4) is configured. Measuring device according to Claim 2 , characterized in that the evaluation logic is configured from a) a first time difference between a second point in time for the second measurement signal and a first point in time for the first measurement signal and b) the first distance (φ1, ψ1; φ3, ψ3) a first speed value for the rotational speed of the wheel (11, 12) and from c) a second time difference between a third point in time for the third measurement signal and the second point in time for the second measurement signal and d) the second distance (φ2, ψ2; φ ₄ , ψ4 ) to determine a second speed value for the rotational speed of the wheel (11, 12). Measuring device according to Claim 3 , characterized in that the evaluation logic is configured to generate a speed signal representative of the rotational speed of the wheel (11, 12) on the basis of the first determined speed value and the second determined speed value. Measuring device according to one of the preceding claims, characterized in that via the first, second and second spacings (φ1, φ2, ψ1, ψ2; φ3, φ4, ψ3, ψ4) to each other on the wheel (11, 12) arranged at different first and second distances third signal transmitter (30-32; 33-35) when the wheel (11, 12) rotates, a characteristic sequence of chronologically successive measurement signals can be generated on the detection device (14). Measuring device according to Claim 5 , characterized in that chronologically successive measurement signals can be generated at chronologically successive first, second and third points in time and an evaluation logic is provided which is configured to recognize that the characteristic sequence has been generated, the first, second and third points in time which measurement signals were generated by the first, second and third signal transmitters (30-32; 33-35) in relation to the first and second distances (φ1, φ2, ψ1, ψ2; φ3, φ4, ψ3, ψ4). Measuring device according to Claim 6 , characterized in that the evaluation logic for recognizing the characteristic sequence is configured to form a first time difference from the first and second points in time and a second time difference from the second and third points in time and a ratio of the first and second time differences with a ratio of the first and to compare second distances (φ1, φ2, ψ1, ψ2; φ3, φ4, ψ3, ψ4). Measuring device according to one of the Claims 2 to 4th and after one of the Claims 5 to 7th , characterized in that the evaluation logic is configured to determine the rotational speed of the wheel (11, 12) only when a generation of the characteristic sequence has been recognized. Measuring device according to one of the preceding claims, characterized in that an evaluation logic is provided which is configured on the basis of a first measurement signal for the first signal transmitter (30, 33) and a third measurement signal for the third signal transmitter (32, 35) and a third Distance (φ1 + φ2, ψ1 + ψ2; φ3 + φ4, ψ3 + ψ4) along the circumferential direction between the first signal transmitter (30, 33) and the third signal transmitter (32, 35) a plausibility check for a using measurement signals of the first, second and third signal generator (30-32, 33-35) to perform the determined rotational speed of the wheel (11, 12). Measuring device according to one of the preceding claims, characterized in that the first distance (φ1, ψ1; φ3, ψ3) is a multiple of the second distance (φ2, ψ2; φ4, ψ4) or, conversely, the second distance (φ2, ψ2; φ4, ψ4) is a multiple of the first distance (φ1, ψ1; φ3, ψ3). Measuring device according to one of the preceding claims, characterized in that at least two groups (3A, 3B) each with first, second and third signal transmitters (30-32, 33-35) are provided on the wheel (11, 12). Measuring device according to one of the preceding claims, characterized in that at least one of the first, second and third signal transmitters comprises a magnet (30-32, 33-35) and / or influences a light beam generated by the detection device. Two-wheeler, in particular an electric bicycle (1), with a measuring device according to one of the Claims 1 to 12th . Method for determining a rotational speed of a wheel (11, 12) rotatable about an axis of rotation (D) on a vehicle (1), in which at least one detection device (14) generates measurement signals with which a rotational speed of the wheel (11, 12 ) can be determined, and - with a first signal transmitter (30, 33) provided on the wheel (11, 12) at least one measurement signal is generated on the detection device (14) when the wheel (11, 12) is about the axis of rotation (D) rotated and thereby the first signal transmitter (30, 33) is displaced relative to the detection device (14), characterized in that at least one second signal transmitter (31, 34) and at least one third signal transmitter (32, 35) on the wheel (11, 12) are provided, which are used to determine the rotational speed of the wheel (11, 12), and the second signal transmitter (31, 34) along a circumferential direction around the axis of rotation (D) to the first signal transmitter (30, 33) in one first distance (φ1, ψ1; φ3, ψ3) arranged net and the third signal generator (32, 35) along the circumferential direction to the second signal generator (31, 34) at a second distance (φ2, ψ2; φ4, ψ4) is arranged, which is different from the first distance (φ1, ψ1; φ3, ψ3). Procedure according to Claim 14 , characterized in that the first, second and third signal transmitters (30-32, 33-35) generate a characteristic sequence of chronologically successive measurement signals at the detection device (14) when the wheel (11, 12) rotates.

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