DE102010042258B4 - Electrically operated sensor for detecting a state variable, in particular in a motor vehicle and motor vehicle - Google Patents

Abstract

Electrically operated sensor for detecting a state variable, in particular in a motor vehicle, comprising: a voltage supply for providing a sensor operating voltage; A sensing unit for measuring the state variable and generating sensor signals as a function of the measurement of the state variable; - A terminal (8) for reading the generated sensor signals; characterized in that the sensing unit is configured such that it can generate a first sensor signal at the terminal (8) and a second, different from the first sensor signal sensor signal at the terminal (8), wherein the first and second sensor signal based on the same measurement of the state variable and wherein the second sensor signal is a digital signal based on a predetermined communication protocol.

Description

The invention relates to an electrically operated sensor for detecting a state variable, in particular in a motor vehicle, as well as a corresponding motor vehicle.

Electrically operated sensors are used in a variety of technical applications for detecting state variables. In this case, a state variable is understood here and below as meaning a measured value determined by the sensor or a plurality of measured values determined via the sensor, wherein the sensor generates corresponding sensor signals from the detected measured values. These sensor signals are usually read out via a corresponding connection on the sensor, it being important to ensure that the unit which processes the read-out sensor signals has the same interface specification as the connection to the sensor. Particularly when using sensors in motor vehicles, there is the problem that control devices which process corresponding sensor signals are often based on different communication technologies, so that, depending on the control unit used, a corresponding sensor must be provided which provides the sensor signals in the communication technology of the control unit.

The publication DE 103 60 422 A1 discloses a motor vehicle with a control device and an electrically connected sensor. The sensor has two electrically independent outputs for the same sensor signal. These outputs are connected via two separate electrical signal lines to two separate inputs of the controller.

The document DE 199 07 141 A1 discloses an electronically controlled shift system for a synchronized manual transmission of a motor vehicle. Based on the gear selected via a shift lever, an actuator actuates a shift rod of the transmission using various electrical signals.

In the publication DE 199 50 764 C1 a device for monitoring a control in a motor vehicle is described, wherein a sensor unit provides a first and a second signal via different signal transmission means. The first and second signals characterize the same size. An error is detected if both signals deviate from an expected value.

The object of the invention is to provide an electrically operated sensor which is compatible with different, the sensor signals processing device types.

This object is achieved by the sensor according to claim 1. Further developments of the invention are defined in the dependent claims.

The sensor according to the invention serves to detect a state variable and, in particular, to detect a state variable in a motor vehicle. The sensor comprises a voltage supply for providing the sensor operating voltage and a sensing unit for measuring the state variable and for generating sensor signals as a function of the measurement of the state variable. Furthermore, a connection for reading out the generated sensor signals via a corresponding processing unit is provided on the sensor. The sensor unit of the sensor is configured such that it can generate a first sensor signal at the terminal, wherein the first and second sensor signal are based on the same measurement of the state variable. In this case, the second sensor signal is a digital signal based on a predetermined communication protocol. A predetermined communication protocol represents any standardized protocol with which signals are coded according to predetermined rules. Examples of such predetermined communication protocols are mentioned below.

The sensor according to the invention is characterized in that it can provide two different sensor signals starting from the same measurement, so that the sensor can be connected via its connection both to a processing unit which understands only the first sensor signals and to a processing unit which only understands the second sensor signals based on the given communication protocol. In this way, the sensor is compatible with various, the sensor signals processing controllers, so that not a separate sensor must be used for each type of controller. Optionally, there is also the possibility that the first and second sensor signal is evaluated by the control unit, whereby the reliability is increased.

According to the invention, if appropriate only one connection element or contact element / contact pin can be provided in the corresponding connection for reading out the first or second signal. About a suitable adaptation of the sensing unit, z. B. via a certain energization, the sensing unit is fixed to the provision of the first or second sensor signal to the contact pin. In a particularly preferred embodiment, however, the sensor unit of the sensor is embodied such that, during operation of the sensor, it receives the first sensor signal at a first contact element of the terminal and the second sensor signal at a second contact element of the terminal generated. Depending on the connected processing unit, the first or the second contact element is used for reading the sensor signals.

In a particularly preferred embodiment of the sensor according to the invention, its voltage supply is part of the connection. In this case, the terminal comprises a contact element for connecting the sensor operating voltage and a contact element for connecting ground.

In a further, particularly preferred embodiment, the sensor according to the invention is a position sensor, in particular a non-contact position sensor whose sensing unit measures a position as a state variable. Preferably, the position sensor is a sensor attachable to the gearbox of a motor vehicle, which detects the position of the shift shaft of the gearbox during operation, from which at least one shift gear position set by the vehicle user and in particular the neutral gear position (i.e., no gear engaged) can be derived.

As a non-contact position sensor, various types of sensors can be used. In particular, z. B. a PLCD sensor (PLCD = Permanent Linear Contactless Displacement) can be used, whose structure is known from the prior art. The operation of this sensor will be explained in more detail in the detailed description. In a particularly preferred embodiment, a known per se Hall sensor is used as a position sensor, wherein this sensor is preferably designed such that it can measure a three-dimensional position. In combination with the type of sensor described above, which is mounted on the gearbox of a motor vehicle, it can be determined with high precision each set by the vehicle user Schaltgangposition.

In a further, preferred embodiment of the sensor according to the invention, the first sensor signal is a PWM signal (PWM = pulse width modulation). The pulse width modulation is a known modulation method. In this case, the test ratio of the signal is modulated with a constant frequency and the information is digitally encoded via this. If the sensor is a sensor mounted on the gearbox of a motor vehicle, the test ratio of the PWM signal in a predetermined range of values preferably encodes the shift position of the shift shaft variable by a shift of a gearshift lever, and it can be inferred from the shift position whether the neutral position is set by the vehicle user , A switching movement represents a movement of the gearshift lever, with a gear is engaged, as described below with reference to 3 is explained in more detail. In a further preferred variant, the information is encoded by the PWM signal by setting a predetermined test ratio, in particular outside the value range for encoding the shift position, that the reverse position is set by the vehicle user. This variant has the advantage that it is possible to dispense with the use of a separate mechanical sensor for detecting the reverse gear position. If appropriate, the first signal can also be an analog voltage signal instead of a digital PWM signal, the corresponding information being coded via the analog voltage value.

In a particularly preferred embodiment of the sensor according to the invention, the second sensor signal is a digital signal based on the SENT protocol (SENT = Single Edge Nibble Transmission). This protocol is known from the prior art and is to be increasingly used in the automotive sector for the transmission of sensor signals. The SENT protocol is a standardized communication protocol according to the SAE standard J2716. It allows a higher transmission power than the pulse width modulation. The detailed description explains the basic features of the SENT protocol in more detail. Another variant of a protocol which can be used to generate the second sensor signal is the so-called PSI5 protocol (PSI5 = Peripheral Sensor Interface 5).

In a further variant of the method according to the invention, the second sensor signal encodes the three-dimensional position of the switching shaft, from which the switching gear position set by the vehicle user can be derived. This variant is in particular combined with a corresponding Hall sensor, which can measure a three-dimensional position value. By detecting a three-dimensional position of the shift shaft can be dispensed with the use of a separate mechanical sensor for detecting the reverse position again, because this position can be derived from the three-dimensional position.

In a further, particularly preferred embodiment of the sensor according to the invention, the sensing unit comprises at least one IC chip for measuring the state variable and generating the first and second sensor signals. In particular, a first and a second chip may be provided which, depending on the application, assume corresponding tasks within the scope of measurement and signal generation. In one embodiment of the sensor according to the invention, the first chip serves to generate the first sensor signal, whereas the second chip to the Generation of the second sensor signal is used. In a preferred variant of this embodiment, during operation of the sensor, the first or the second chip can be deactivated so that, depending on whether the first or second sensor signal is required by the connected processing unit, the corresponding chip which generates the respective other sensor signal is switched off which saves energy. The deactivation of a chip can take place, for example, in that the contact element of the terminal, at which the first or second chip to be deactivated generates the first or second sensor signal, is connected to one pole of the sensor operating voltage. The concern of the corresponding voltage value or of ground at the corresponding contact element is detected by the chip, which then stops the output and calculation of its sensor signal. The deactivation can z. B. by the connection element, which is connected to the terminal of the sensor. In this case, a corresponding bridge can be provided in the connection element, via which a pole of the operating voltage is connected to the contact element of the chip to be deactivated.

In a further, preferred embodiment, the connection of the sensor according to the invention is a plug, inside which preferably at least the first and second contact element and optionally also the contact elements for connecting the sensor operating voltage or ground in the form of contact pins are provided. In this case, a suitable, known from the prior art plug can be used.

In addition to the sensor described above, the invention further relates to a motor vehicle in which at least one such sensor is installed. Preferably, the sensor is the position sensor described above, with which the position of the switching shaft of the gearbox of the motor vehicle is detected. In this case, the first and / or the second sensor signal are transmitted via a cable harness connected to the terminal to an engine control unit. Preferably, the engine control unit initiates the automatic stopping or starting of the engine of the vehicle, if it results from the first and / or second sensor signal that the gearshift position set by the vehicle user is the neutral gear position and all other predetermined criteria, for example a sufficient starter battery voltage for the Engine start, for stopping or starting the engine are met. As a result, a start-stop system in a vehicle with a manual transmission can be realized in a simple manner.

In a further variant of the motor vehicle according to the invention, the engine control unit causes one or more predetermined actions on the vehicle, such. B. the turning on of one or more reversing lights on the vehicle or the activation of distance monitoring sensors or other actuators (eg., Turning of the front passenger mirror down), if it is clear from the first and / or second sensor signal that set by the vehicle user Schaltgangposition the Reverse position is. As already mentioned above, it is therefore possible to dispense with an additional mechanical sensor for detecting the reverse position.

Embodiments of the invention are described below in detail with reference to the accompanying drawings.

Show it:

1 a perspective view of a sensor according to an embodiment of the invention;

2 a plan view of the plug of the sensor of 1 , wherein a PWM output of the sensor is also reproduced, and

3 the various positions of a gear shift lever in a motor vehicle to illustrate the associated switching or selection positions of the shift shaft in the motor vehicle.

An embodiment of the invention will be described below with reference to a sensor for use in a motor vehicle. The sensor serves to detect the position of the shift shaft on a manual transmission of the motor vehicle. Based on the determined position can then be determined whether the vehicle user the neutral position (ie no gear engaged) has been set. In this case, the shift shaft is arranged in the neutral gear position in a predetermined shift position. The data of the sensor are transmitted to an engine control unit, which processes the data appropriately. Preferably, a start-stop system is coupled to the neutral position, which turns off the engine at standstill of the vehicle to save energy. 3 illustrates how the shift position of the shift shaft can be changed by a manually operated gear shift lever in the interior of a motor vehicle. It shows 3 the various shift gates of the gearshift lever, wherein the shift lanes are indicated by vertical lines. There is a shift gate for shifting into reverse gear R, a shift gate for shifting into forward gear V1 or the forward gear V2, a shift gate for shifting to forward gear V3 and forward gear V4 and a shift gate for shifting into forward gear V5 or the Forward gear V6. By the movement of the gear shift lever within an arbitrary shift gate along the double arrow SP while the shift position of the shift shaft is changed in the transmission, wherein in the event that the shift lever is on the horizontal line L, the neutral gear position is set. If, in this neutral gear position, the gear shift lever is moved in the direction of the horizontal double arrow WP, the selection position of the shift shaft is thereby changed, but the shift position remains unchanged. Only when the movement of the gear shift lever takes place in the vertical direction within a shift gate, this leads to a change in the shift position of the shift shaft.

1 shows a perspective view of an embodiment of the sensor according to the invention. The sensor 1 includes a housing 2 with a housing top 3 and a case back 3 ' ( 2 ). On the housing are flanges 4 and 6 with respective openings 5 and 7 provided, via which the sensor can be attached to the transmission housing of a gearbox. The position sensing is done via the bottom 3 ' , wherein a corresponding sensing unit is provided in the interior of the sensor, which determines the position of an opposite, positioned on the switching shaft encoder contactless. The Sensiereinheit can z. B. be designed as a PLCD sensor. The operating principle of such sensors is known per se from the prior art. To sense this is a fed with AC primary coil inside the housing 2 provided, this coil interacts with a corresponding permanent magnet, which is attached to the sound wave. If the permanent magnet is located in the region of the primary coil, a local magnetic saturation and thus a virtual division of the core of the coil is thereby achieved. About Auswertespulen, which are also inside the case 2 Then, depending on the position of the magnet along the primary coil, a voltage is induced, from which the switching position of the switching shaft in the transmission, but not its selection position, can be determined.

The sensor signals are in the sensor of 1 via a connector in the form of a plug 8th read, wherein in the interior of the plug, a corresponding mating plug is inserted, which leads to the wiring harness of the vehicle and transmits sensor signals to the engine control unit of the vehicle. In this case, via the connection between the plug and the mating connector, the supply of a voltage which the sensor requires as part of its operation also takes place. For fixing the mating connector in the plug 8th is an opening 9 provided in which engages a corresponding nose of the mating connector. The plug 8th is in itself known from the prior art and will therefore not be explained in detail. The sensor of 1 In the embodiment described here, among other things, it supplies a digital PWM signal as the first sensor signal, which is calculated by the sensing unit as a function of its position measurement. The sensing unit contains a corresponding semiconductor chip, which processes the measurements and generates the PWM signal.

Conventionally, sensors are designed according to the above-described functional principle only for generating a PWM signal. In contrast, the sensor allows the 1 Now, however, in addition to the generation of a PWM signal, the generation of a second sensor signal, which is based on the same measurement as the PWM signal, but encodes the values measured via the sensing unit in a different manner. Essential to the invention is that the second sensor signal is a digital signal, which is based on a predetermined communication protocol. In the embodiment described here, the communication protocol used is the SENT protocol (SENT = Single Edge Nibble Transmission) known from the prior art, which is to be used more and more often in the automotive sector for transmitting information.

The SENT protocol allows the standardized transmission of information, which is not the case with PWM signals, because the pulse width modulation is a modulation type, which is not standardized. In contrast, the SENT protocol is an industry standard. The hardware structure for processing signals of this protocol is similar to the processing of PWM signals, but the transmission performance of the SENT protocol is significantly improved. As part of the transmission of a PWM signal, the information is transmitted within a cycle time based on the duty cycle, which is indicated as a percentage value of the time component in the cycle time in which the state of the signal is set to the value "high". In contrast, in the context of the SENT protocol, the information content is transmitted in the falling signal edge (single edge), wherein the time between two falling pulse edges contains the information of a so-called nibble. One cycle contains eight nibbles. The transmitted value of a nibble is proportional to the time between two falling pulse edges, over which period a 4-bit word is encoded. The transmission is synchronized by a synchronization pulse, which is transmitted before the nibbles.

To be in the sensor of the 1 now to enable the provision of the measured position both based on a PWM signal and based on a SENT signal are corresponding contact elements in the plug 8th of the 1 intended. This is going out 2 can be seen, which in the upper part is a plan view of the sensor 1 on the side of the plug 8th shows. It can be seen that the inside of the plug 8th four contact pins 11 which are provided with corresponding numbers 1, 2, 3 and 4. In the embodiment described here, the PWM signal is provided via the contact pin number 1 and the SENT signal via the contact pin number 3. The chip of the sensor is programmed in such a way that it generates from the measurement a corresponding signal of the SENT protocol with the same information content as the PWM signal. The contact pin number 2 serves in the plug 8th for supplying the supply voltage and the contact pin with the number 4 is the ground connection. By means of corresponding contact sockets of the corresponding mating connector, the signals can then be read or the operating voltage supplied to the sensor. Depending on which type of engine control unit is connected, the corresponding contact pin number 1 for reading the PWM signal or the contact pin number 3 for reading the SENT signal via a wiring harness with the engine control unit is connected.

In the lower part of the 2 Furthermore, the sensing based on the PWM signal is indicated. Here are relative to the sensory bottom 3 ' of the sensor 1 reproduced two different positions of a magnet M, which is mounted as part of the use of the sensor to the shift shaft of the transmission. The magnet interacts with the corresponding coil of the PLCD element inside the sensor housing. The measuring range of the sensor is denoted by MB and is used to detect a change in position of the magnet, which is caused by a change in the switching position of the shift shaft. Exemplary is in 2 a positional shift of the magnet along the horizontal axis d between 0 mm and 15 mm is shown. Along the corresponding vertical axis OP, the PWM value output via the corresponding contact pin in the form of the test ratio in percent for the different distance values in the measuring range MB is indicated. It can be seen that with increasing distance d, the PWM values decrease linearly, with the test ratio being 90% for the distance of 0 mm and 10% for the distance of 15 mm. The middle of the measuring range is designated by the reference symbol C. Within a predetermined range around the center of the measuring range, a corresponding PWM value is classified as neutral position by the engine control unit (not shown) to which the PWM signal is transmitted. Should now be a newer engine control unit are used, which only understands the SENT protocol, the sensor 1 continue to be used because this sensor provides the same reading based on coding in the SENT protocol in addition to the PWM signal. In this way, the sensor is compatible with both engine controllers that understand only PWM signals and engine controllers that process information based on the SENT protocol.

In the foregoing, a sensor has been described which relies on position sensing on PLCD technology. The invention has further advantages if, instead of a PLCD sensor, a Hall sensor is used with which the determination of a three-dimensional position of the switching shaft is made possible. Hall sensors are known per se from the prior art and are based on the Hall effect, according to which a voltage is induced in a current-carrying conductor which is in a stationary magnetic field. In analogy to PLCD sensors, a corresponding permanent magnet is used in the measurement with a Hall sensor, which is attached to the switching shaft and over which the voltage induction is caused, whereby the position of the switching shaft can be determined.

To realize the Hall sensor known per se Hall-sensing can be used. For example, a monolithic semiconductor chip of the company Melexis can be used, which is sensitive to the magnetic flux density parallel to a surface and is sensitive to all three components of the magnetic flux, so that a three-dimensional position determination of a magnet and thereby the switching shaft is made possible. As a result, not only the shift position of the shift shaft can be determined, but also a change in position of the shift shaft, which is caused by the gear selection of a vehicle user (movement of the gear shift lever in 3 along the line L). In this way, it can be determined which shift gear position is set by the vehicle user. In contrast to a PLCD sensor can thus not only be sensed whether the lever is in neutral position, but it can also be derived, which forward gear is engaged or whether the reverse gear is engaged.

In the context of using a Hall-sensing element in the sensor of 1 the chip of the sensing unit is programmed to provide the same PWM signals as a corresponding PLCD sensor in dependence on the switching position of the switching shaft. In contrast to this, as part of the signal generation for the SENT protocol, the information about the three-dimensional position of the switching shaft is now encoded in the SENT signal. A newer engine control unit, which processes this SENT signal, can then derive further information from this signal. In particular, it can detect the engaged gear. Thus, z. B. the engagement of the reverse gear are sensed and based on the switching on of the reversing lights of the motor vehicle are caused. In this case, it is then no longer necessary to provide a separate mechanical switch on the selector shaft, with which the engagement of the reverse gear is currently detected.

As part of the use of a Hall sensor may optionally be encoded in the PWM signal, the information about the engagement of the reverse gear. This can be done, for example, in that the chip of the sensor is programmed such that it outputs a predetermined test ratio outside the measuring range MB for corresponding three-dimensional position values which correspond to the reverse gear. In this case, the engine control unit is known that this predetermined duty cycle corresponds to the engagement of the reverse gear. Thus, even with engine control units, which only understand the PWM signal, the switching on of the reversing lights can be initiated when engaging the reverse gear, so that even for such engine control units can be dispensed with a mechanical switch for detecting the engagement of the reverse gear.

The embodiments of the sensor according to the invention described above have a number of advantages. In particular, the sensor facilitates the transition to a new transmission protocol, since it also provides sensor signals based on the SENT protocol in addition to sensor signals based on pulse width modulation, wherein the signal transmission by means of the SENT protocol is much more powerful than the signal transmission via pulse width modulation. The sensor is backwards compatible, as it continues to support the generation of PWM signals, which means that currently used engine control units can also be connected to the sensor. In addition, further advantages result from the use of a Hall sensor for three-dimensional position sensing. In particular, this makes it possible to determine the gear engaged by the vehicle user. Above all, the engagement of the reverse gear can be sensed, so that it is possible to dispense with a further mechanical switch with which the engagement of the reverse gear is detected.

Claims (20)

Electrically operated sensor for detecting a state variable, in particular in a motor vehicle, comprising: a voltage supply for providing a sensor operating voltage; A sensing unit for measuring the state variable and generating sensor signals as a function of the measurement of the state variable; - a connection ( 8th ) for reading out the generated sensor signals; characterized in that the sensing unit is configured to receive a first sensor signal at the port ( 8th ) and a second, different from the first sensor signal sensor signal at the terminal ( 8th ), wherein the first and second sensor signals are based on the same measurement of the state quantity, and wherein the second sensor signal is a digital signal based on a predetermined communication protocol. Sensor according to claim 1, characterized in that the sensing unit is designed such that during operation of the sensor ( 1 ) the first sensor signal at a first contact element ( 11 ) of the connection ( 8th ) and the second sensor signal at a second contact element ( 11 ) of the connection ( 8th ) generated. Sensor according to claim 1 or 2, characterized in that the voltage supply part of the terminal ( 8th ), the connection ( 8th ) a contact element ( 11 ) for connecting the sensor operating voltage and a contact element ( 11 ) for connecting ground. Sensor according to one of the preceding claims, characterized in that the sensor is a position sensor whose sensing unit measures a position as a state variable. Sensor according to claim 4, characterized in that the position sensor can be attached to the gearbox of a motor vehicle sensor ( 1 ), which detects the position of the switching shaft of the gearbox during operation, from which at least one switching gear position set by the vehicle user can be derived. Sensor according to claim 4 or 5, characterized in that the position sensor is a PLCD sensor or a Hall sensor, wherein the Hall sensor, a three-dimensional position can be measured. Sensor according to one of the preceding claims, characterized in that the first sensor signal is a digital PWM signal. A sensor according to claim 7, when dependent on claim 5, characterized in that the duty cycle of the PWM signal in a predetermined value range encodes the shifting position of the gearshift lever by means of a shifting movement of the gearshift shaft, wherein the Switching position can be derived whether the neutral gear position is set by the vehicle user. A sensor according to claim 8, characterized in that a predetermined duty cycle of the PWM signal encodes the information that the reverse position is set by the vehicle user. Sensor according to one of the preceding claims, characterized in that the second sensor signal is a digital signal based on the SENT protocol or the PSI5 protocol. Sensor according to one of the preceding claims, when dependent on claim 5, characterized in that the second sensor signal encodes the three-dimensional position of the switching shaft, from which the set by the vehicle user Schaltgangposition is derivable. Sensor according to one of the preceding claims, characterized in that the sensing unit comprises at least one chip for measuring the state variable and generating the first and second sensor signal. Sensor according to claim 12, characterized in that a first and a second chip is provided. Sensor according to claim 13, characterized in that the first chip is used to generate the first sensor signal and the second chip is used to generate the second sensor signal. Sensor according to claim 14, characterized in that during operation of the sensor ( 1 ) the first or the second chip can be deactivated, in particular by the contact element ( 11 ) of the connection ( 8th ) at which the first or second chip to be deactivated generates the first or second sensor signal is connected to a pole of the sensor operating voltage. Sensor according to one of the preceding claims, characterized in that the connection ( 8th ) is a plug. Motor vehicle, characterized in that the motor vehicle has a sensor ( 1 ) according to one of the preceding claims. Motor vehicle according to claim 17 with a sensor according to claim 5, characterized in that during operation of the sensor ( 1 ) the first and / or the second sensor signal are transmitted via a harness connected to the terminal to an engine control unit. Motor vehicle according to claim 18, characterized in that the engine control unit is configured such that it causes the automatic stopping or starting the engine of the vehicle, if it is clear from the first and / or second sensor signal that the gearshift position set by the vehicle user is the neutral gear position and all other predetermined criteria for stopping or starting the engine are met. Motor vehicle according to claim 18 or 19, characterized in that the engine control unit is configured such that it causes one or more predetermined actions on the motor vehicle, if it is clear from the first and / or second sensor signal that the gearshift position set by the vehicle user is the reverse gear position.

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