DE19718641B4 - Air spring measuring system with ultrasonic arrangement - Google Patents

Abstract

A method for non-contact distance measurement in a motor vehicle air spring with a central control and evaluation (control unit (4)), each by a two-wire line (12a to 12d), each with a decentralized attached to the air springs ultrasonic device (sensor (2)) is connected , with the following process steps:
- A block flow control (42) selects via a block multiplexer (40) in the control unit (4) to be queried sensor (2) and sets via a switch S1 (38) in the control unit (4) the level Ub to the with the sensor ( 2) connected line (12a to 12d);
- Then the sensor (2) charges its energy store (14);
- The block sequence control (42) sets after a predetermined time, which depends on the energy storage (14) in the sensor (2), the level U2, which is smaller than the level Ub, to the sensor (2) connected line ( 12a to 12d) by bringing the switch S1 (38) to the position 2;
- at the same time ...

Description

The invention relates to a method for non-contact distance measurement in a motor vehicle air spring with a central control and evaluation, which is connected in each case with a decentralized attached to the air springs ultrasonic device each by a two-wire line, in particular according to the pulse / echo method. Moreover, the invention relates to a device for carrying out the method for non-contact distance measurement in a motor vehicle air spring with a central control and evaluation, which is connected in each case by a two-wire line, each with a decentralized attached to the air springs ultrasonic device, in particular after the pulse / echo -Method. The arrangement preferably comprises a chassis-fixed transmission / reception component and an axis-fixed reflector component, as for example from the DE 36 20 957 A1 is already known. There, the central control and evaluation device and the electrical power supply are each connected by a multicore cable, each with a decentralized attached to the air springs ultrasonic device (column 3, lines 22 to 27).

Airborne distance measurement is used, for example, in the level measurement of containers, for the measurement of living spaces, for distance measurement when parking with the motor vehicle, for distance measurement in autofocus cameras, etc. In the published patent application DE 36 20 957 A1 For vehicle use, an ultrasonic sensor is described within an air spring. In the U.S. Patent 4,798,369 a comparable air spring control system is shown, which is also based on the determination of the spring height by means of ultrasonic sensors.

Either put the transmitters as well as the receivers electroacoustic transducers for operation on an associated drive train and evaluation electronics connected to the power supply Need to become.

There usually on all four equipped with air springs wheels such ultrasonic devices too install is for that Overall, a comprehensive wiring required.

At the However, the use of sensors in vehicles one strives, if possible to drive little cabling.

The Sensors are generally self-intelligence, i. a signal processing and Correction equipped and require for this purpose at least three connecting wires. If several identical sensors are to be installed in the vehicle, that's what they are for also several times to provide necessary electronic components, which is uneconomical. In ultrasound-sensitive vehicles is increasing the effort with the number of existing axes.

Of the Invention is based on the desire, the electronic components To distribute so that the respective sensor only a small part assigned to the necessary function groups and the rest in one central control unit is housed. That is, the object of the invention is based on as economical as possible Division of functions into a central unit and wheel-related Units together with communication between the units.

outgoing From this endeavor, the invention has the concrete goal, the connection between wheel-related sensor components and central control unit respectively to realize with a two-wire line.

• – ein Baustein Ablaufsteuerung wählt über einen Baustein Multiplexer im Steuergerät einen abzufragenden Sensor an und legt über einen Schalter S1 im Steuergerät den Pegel Ub auf die mit dem Sensor verbundene Leitung;
• – daraufhin lädt der Sensor seinen Energiespeicher auf;
• – der Baustein Ablaufsteuerung legt nach einer vorgegebenen Zeit, die von dem Energiespeicher im Sensor abhängt, den Pegel U2, der kleiner als der Pegel Ub ist, auf die mit dem Sensor verbundene Leitung, indem der Schalter S1 in die Position 2 gebracht wird;
• – gleichzeitig wird ein Baustein Zeitmessung im Steuergerät gestartet;
• – der Sensor benutzt die Flanke Ub → U2, um einen Ultraschall-Impuls abzuschicken;
• – wenn das Echo beim Sensor angekommen und erkannt worden ist, wird ein Schalter S2 im Sensor geschlossen und damit die mit dem Sensor verbundene Leitung auf den Pegel 0 gelegt;
• – durch den vom Sensor erzeugten Pegelübergang U2 → 0 wird der Zeitmesser gestoppt.

The object is achieved by a method for non-contact distance measurement in a motor vehicle air spring with a central control and evaluation (control unit), which is connected by a two-wire line, each with a decentralized attached to the air springs ultrasonic device (sensor), solved with the following method steps :

• - A block flow control selects via a block multiplexer in the control unit to be queried sensor and sets via a switch S1 in the control unit the level Ub to the sensor connected to the line;
• - Then the sensor charges its energy storage;
• After a predetermined time, which depends on the energy store in the sensor, the flow control module sets the level U2, which is lower than the level Ub, to the line connected to the sensor by bringing the switch S1 into position 2;
• - At the same time a module time measurement is started in the control unit;
• The sensor uses the edge Ub → U2 to send an ultrasonic pulse;
• - When the echo has arrived at the sensor and detected, a switch S2 is closed in the sensor and thus the line connected to the sensor is set to level 0;
• - By the level generated by the sensor level transition U2 → 0, the timer is stopped.

advantageous Further developments of the method are mentioned in the dependent claims 2-4.

Farther The object is achieved by a device having the features of claim 5 solved.

The Essence of the invention consists in a multiple utilization of the compound between decentralized and centralized unit, which results in an otherwise extensive multi-wiring can be dispensed with.

The Electronic components are designed so that on the respective Two-wire line the individual phases of an ultrasonic transit time measurement, such as e.g. Start of the pulse and notification of the time of an echo controlled by level transitions become.

"Phase" here does not mean "line", but "phase" is a time temporary switching state. There are three different ones Switching states ("phases") differ: "Power supply of the wheel-related units "," Start the transmit pulse "and" recognize of the echo ".

Of the Energy transport to the sensor happens in a separate phase, in a memory is being loaded.

By the division of electronics into wheel-related decentralized components and a total of only one central unit become multiple building blocks, the otherwise at each wheel-related decentralized unit and thus in multiple execution would be required just needed. This advantage, usually through an elevated Cabling effort would have been nullified, remains because of the invention by Time division multiplexed "two-wire connection" fully preserved.

Of the The switch S2 parallel to the resistor R2 may be used for this purpose be to transmit a time-period proportional temperature information. This can be done in such a way that the switch S2 after the Echo detection temperature dependent delayed is closed. Will in the ultrasonic measurement method a reference distance used, then the echo caused by this reference distance to a short closing of the switch S2 lead. Preferably, the reference time is stored as an intermediate time.

in the The following will be the electronic invention Circuit arrangement, as according to the invention for operation of the air spring measuring system is provided, explained in more detail with reference to a block diagram.

The arrangement consists of one of the air springs (ie decentralized) mounted ultrasonic device ("sensor") 2 and a central control and evaluation device ("control device") 4 , each through a two-wire line 12 connected to each other.

Each decentralized ultrasound device 2 includes a serving as a transmitter and receiver (ultra) sound transducer 6 , a switch (S3) 28 who the ultrasound transducer 6 switches between a send and receive mode back and forth; a power supply "sensor" 8th ; a transmission amplifier 18 , a burst generator 16 is downstream; a reception amplifier 20 with a subsequent module "Echo recognition" 22 ,

This module "echo detection" 22 Used for echo signal detection and for reporting the echo via the respective two-wire line 12a . 12b . 12c or 12d to the control unit 4 ,

In addition, the decentralized ultrasonic device includes 2 one to the operating voltage "sensor" 8th connected and for the transmitter 18 and the receiver 20 provided voltage regulator 10 ,

Finally, there is another resistor (R2) 24 and a switch (S2) 26 ,

The central control and evaluation device ("control device") 4 includes: a power supply (Ub) 34 with a ballast resistor (R1) 36 and a switch (S1) 38 (with the two switching states "1" and "2"); a multiplexer 40 (For temporally successive control of the decentralized ultrasound device 2 ); a block "sequence control" 42 ; a module "time measurement" 44 with cache; a module "distance calculation" 46 and finally a line 48 for signal processing.

The mode of operation of the circuit should be shown in the following sequence description:
The flow control 42 dials through the multiplexer 40 the queried decentralized air spring-related ultrasound device (called "sensor" for short 2 ) and put over the switch (S1) 38 the level Ub to the respective line 12a . 12b . 12c respectively. 12d ,

The "sensor" 2 Charges its energy storage 14 on.

The flow control 42 lays down after a certain amount of time (the energy store 14 in the "sensor" 2 depends) the level U2 (<Ub) 34 on the line 12 by the switch (S1) 38 placed in position "2". At the same time the timer is started.

The "sensor" 2 uses the edge Ub → U2 to the burst generator 16 to start. The generator 16 puts the switch (S3) in position "1", generates a pulse (burst) with a number of square pulses, and then brings the switch (S3) 28 in Position "2". The "sensor" 2 waiting for the incoming echo. Once it has been detected, the switch (S2) 26 closed and thus the line 12 set to the level "0". The duration of this pulse may be fixed or may be used to transmit temperature information. Alternatively, the pulse generated by a reference path may be output.

By the "sensor" 2 generated level transition Ub → 0 is the timer 44 stopped. If a reference distance is used, the reference time must be saved. The transit time is then used taking into account the known burst duration and the temperature information or reference time from the reference measurement to calculate the distance. Subsequently, by the flow control 42 initiated a new measurement cycle.

2

decentralized Air spring-related ultrasound device ("sensor")

4

central Control and evaluation device ("control device")

6

Transmitter / receiver component (Ultrasonic transducer) (can also be two different converters)

8th

Power supply (the decentralized facility)

10

voltage regulators (the decentralized institution)

12 12a, 12b, 12c, 12d

(Food grade) line (Two-wire line) between each decentralized and central unit

14

(Energy) memory (the decentralized institution)

16

burst generator

18

Transmitter amplifier (transmission stage)

20

receiver amplifier

22

Echo detection module

24

resistance R2

26

switch S2

28

switch S3

30

Module "Temperature measurement"

34

Power supply "Ub" of the central facility

36

resistance R1

38

switch S1 (positions "1" and "2")

40

Block "Multiplexer"

42

Block "Sequence control"

44

Module "Time measurement"

46

Block "distance calculation"

48

management for signal processing

Claims (5)

Method for non-contact distance measurement in a motor vehicle air spring with a central control and evaluation device (control device ( 4 )), each by a two-wire line ( 12a to 12d ) each having a decentralized to the air springs mounted ultrasonic device (sensor ( 2 )), with the following method steps: - a flow control module ( 42 ) selects a multiplexer ( 40 ) in the control unit ( 4 ) a sensor to be interrogated ( 2 ) and via a switch S1 ( 38 ) in the control unit ( 4 ) the level Ub to the with the sensor ( 2 ) connected line ( 12a to 12d ); - then the sensor loads ( 2 ) its energy store ( 14 ) on; - the block flow control ( 42 ) after a predetermined time, the energy storage ( 14 ) in the sensor ( 2 ), the level U2, which is lower than the level Ub, to which the sensor ( 2 ) connected line ( 12a to 12d ) by the switch S1 ( 38 ) in the position 2 is brought; - at the same time a building block time measurement ( 44 ) in the control unit ( 4 ) started; - the sensor ( 2 ) uses the edge Ub → U2 to send an ultrasonic pulse; - if the echo at the sensor ( 2 ) has been detected and detected, a switch S2 ( 26 ) in the sensor ( 2 ) and thus with the sensor ( 2 ) connected line ( 12a to 12d ) is set at level 0; - by the sensor ( 2 level transition U2 → 0, the timer ( 44 ) stopped. Method according to Claim 1, characterized in that the time duration for which the switch S2 ( 26 ) is closed, is fixed. Method according to Claim 1, characterized in that the switch S2 ( 26 ) is closed after the echo detection temperature-dependent delayed. Method according to one of Claims 1-3, characterized in that, in the case of the use of a reference path, the echo caused by this reference path leads to a short closing of the switch S2 ( 26 ), whereby the reference time is stored as an intermediate time. Device for carrying out the method for non-contact distance measurement in a motor vehicle air spring according to one of the preceding claims with a central control and evaluation device (control device ( 4 )), each by a two-wire line ( 12a to 12d ) each having a decentralized to the air springs mounted ultrasonic device (sensor ( 2 )): 1. Each distributed ultrasound device (sensor ( 2 )) comprises: 1.1 a transmitter / receiver component ( 6 ) with at least one ultrasonic transducer; 1.2 a power supply ( 8th ) with energy storage ( 14 ); 1.3 a transmitter amplifier ( 18 ); 1.4 a receiver amplifier ( 20 ); 1.5 an echo detection module ( 22 ) for echo signal detection and for reporting the echo via the respective two-wire line ( 12a to 12d ) to the control unit ( 4 ); 1.6 a resistor R2 ( 24 ); 1.7 a switch S2 ( 26 ). 2. The decentralized control and evaluation device (control unit ( 4 )) comprises: 2.1 a power supply Ub ( 34 ) with a ballast resistor R1 ( 36 ) and a switch S1 ( 38 ) with the two switching states "1" and "2"; 2.2 a multiplexer ( 40 ) for temporally successive control of the decentralized ultrasonic device (sensor ( 2 )); 2.3 a block flow control ( 42 ); 2.4 a module time measurement ( 44 ) with cache; 2.5 a block distance calculation ( 46 ) and 2.6 a line for signal processing ( 48 ).