DE10243412A1 - Circuit for hydraulic valve arrangement displacement sensor has microprocessor for combining sensor signals in measurement mode, making communications connection to service device in programming mode - Google Patents

Abstract

The circuit arrangement has two magnetic field sensors parallel to an axis of motion whose sensor voltages are combined into an output signal, a two-pole operating voltage connection, a circuit output and a sensor output. A microprocessor combines the sensor signals and produces output, sensor and switch output signals in a measurement mode and makes a bi-directional communications connection with an external service device in a programming mode. The circuit arrangement has two magnetic field sensors (2) parallel to an axis of motion whose sensor voltages are combined into an output signal, a two-pole operating voltage connection (11), a circuit output (12) and a sensor output (13). A microprocessor (3) combines the sensor signals and produces output, sensor and switch output signals in a measurement mode and makes a bi-directional communications connection with an external service device in a programming mode. Independent claims are also included for the following: (a) a hydraulic valve arrangement (b) and a method of operating a displacement sensor.

Description

The present invention relates to a circuit arrangement for a displacement sensor. Also concerns the invention a hydraulic valve assembly in which a conventional magnetically operated hydraulic valve (also called hydraulic magnet) with such a circuit arrangement is combined. Finally The present invention also relates to a method for Operation of a displacement sensor. The related to the invention used displacement sensor comprises two parallel to a movement axis arranged magnetic field sensors, the sensor voltages to one Output signal linked are, the associated circuit arrangement a two-pole Operating voltage connection, a switching output and a sensor output has.

For controlling hydraulic devices become common So-called hydraulic valves are used by an electromagnet are driven. By different energization of the solenoid coils can do that lengthways an actuator of the hydraulic valve displaceable in a movement axis placed in different positions to control the flow rate the hydraulic fluid in desired Way to influence. For precise control of the hydraulic valve must enable monitors the respective armature position of the electromagnetic actuator what displacement sensors are used for. It is known for such Measuring purposes Differential transformer converter or differential choke converter use. However, these can only be miniaturized to a limited extent relatively expensive to manufacture due to the necessary measuring coils.

From the DE 38 03 293 A1 a magnetically actuated analog electrical displacement transducer for linear movements is known. This uses two Hall sensors, the Hall voltages of which are linked by forming a difference to form an analog electrical output signal which is representative of the position of a permanent magnet which is displaced on the movement axis parallel to the two Hall sensors.

As far as from the DE 38 03 293 A1 If known displacement transducers are to be used as displacement sensors, for example on pneumatic or hydraulic cylinders, an additional circuit arrangement must be provided which enables the Hall sensors to be operated. As a rule, high accuracy is required, particularly in the case of small displacement sensors, so that the magnetic field sensors have to be attached to the measuring section with high mechanical precision. In addition, there is the particular problem that the magnetic field sensors deliver a strongly non-linear output signal, which makes processing in subsequent control systems more difficult. In this context, it is generally known that nonlinear sensors can be calibrated in order to improve the accuracy and to provide a largely linear output signal.

If one the magnetic field sensors assigned circuit arrangement in addition to the provision of the measurement signal calibration of the sensors should also be additional Components and at least other connection points required, via which external programming and control signals are impressed can. This will be additional Connectors or the like required, through which the size of the often miniaturized equipment (e.g. hydraulic magnets) is sometimes significantly enlarged and which increase the total cost of these devices.

An object of the present invention is thus in a circuit arrangement for operating one with two Equipped magnetic field sensors Provide displacement sensor that electronic calibration and linearization of the displacement sensor enables without the need for additional connection elements for one Connection of the circuit arrangement with an external service device are required. Another object of the invention is a hydraulic valve assembly to provide, in which such a circuit arrangement is coupled to a hydraulic valve and which in this way a reduction in that for the Requires space required displacement sensor.

These and other tasks will be from the circuit arrangement according to the invention met whose Features essential to the invention are specified in appended claim 1.

The advantage of including one Microprocessor, which is in a measurement mode and a programming mode can mainly be operated that the magnetic field sensors are calibrated can be without that additional connectors on the displacement sensor are required. Switching between operating modes the microprocessor is initiated by a switching element, which monitors the voltage potential at the sensor output and / or at the switching output and delivers a corresponding switching signal to the microprocessor. This makes it possible by embossing a voltage signal at one of these two outputs To put the microprocessor in the programming mode, in which the switching output and the sensor output for handling a bidirectional Data communication can be made usable.

According to an advantageous embodiment, the switchover element is formed by a voltage divider, which generates a switchover signal when a switchover potential is present and delivers it to a further analog / digital converter input of the microprocessor. The microprocessor is programmed so that it recognizes the changeover signal at this converter input, for example during an initialization routine, and then the ge required operating mode.

A further developed embodiment is characterized by the fact that the switching element is a two-stage Switching signal can be generated so that the programming mode divided into a calibration mode and a communication mode in which the microprocessor performs different tasks.

The circuit arrangement is preferably included equipped with a four-pin connector, via which the coupling to an external service device is made. about The operating voltage is provided in all operating modes via two connection poles. The remaining two connection poles are used as measuring outputs in measuring mode and sensor output operated while in programming mode the switching output for the transmission of a clock signal and the sensor output for transmission of data is used.

The circuit arrangement according to the invention can used particularly advantageously in a hydraulic valve arrangement become. This makes it possible Use magnetic field sensors to detect the position of the actuator, whereby these sensors can be calibrated and at the same time linearization of the output signal possible is without that for it additional plug connectors or the like would be required on the hydraulic valve assembly, so that the desired Size of one equipped with the circuit arrangement hydraulic valve despite improved sensor technology can be maintained.

Has proven to be particularly advantageous the use of Hall sensors as magnetic field sensors. in the The invention is therefore also described below with regard to its use described such Hall sensors. However, it should be pointed out that other sensors, such as magnetoresistive sensors used can be.

Other advantages, details and Further developments result from the following description preferred embodiments the invention, with reference to the drawing. Show it:

1 a block diagram of a preferred embodiment of a circuit arrangement for a displacement sensor;

2 a simplified program flow chart of the operation of the circuit arrangement;

3 a block diagram of an external service device, which the programming of the in 1 circuit arrangement shown serves;

4 a simplified sectional view of a hydraulic valve assembly according to the invention with two Hall sensors.

1 shows a simplified block diagram of a circuit arrangement according to the invention 1 for operating a displacement sensor. The circuit arrangement comprises two Hall sensors as sensor elements 2 that send their Hall voltages to a microprocessor 3 provide. The microprocessor 3 receives the Hall voltages at a first analog / digital converter input 4 and at a second analog / digital converter input 5. If, as in the example shown, a PIC 16C717 is used as the microprocessor, the circuit arrangement also contains an oscillator 6 which supplies a clock signal to the microprocessor. In other embodiments, the clock generation could also be integrated in the microprocessor. Likewise, in the embodiment shown, there is a separate storage element 7 provided in which data and program instructions can be stored. An EEPROM is preferably used as the memory element, which is connected to the microprocessor 3 communicated.

The circuit arrangement is connected via a sensor connection 10 , which is designed for example as a four-pole connector. The connector 10 includes two operating voltage connections 11 , via which the circuit arrangement is supplied with the required operating voltage, for example 24 volt DC voltage. The sensor connector also includes 10 a switching output 12 for emitting a switching signal and a sensor output 13 , on which a sensor signal is provided. In principle, a screw connection, four individual contact pins or similar contact elements could also be used as the connecting element.

The circuit arrangement expediently contains 1 a voltage regulator 15 , which provides the required operating voltages to the microprocessor and the other components of the circuit arrangement in the desired quality.

The entire circuit arrangement 1 and especially the microprocessor 3 can be operated in different operating modes, the function and mode of operation of which is explained below. The known function of a displacement sensor is perceived by the circuit arrangement in the measuring mode. The two Hall sensors 2 are arranged parallel to a movement axis on which a permanent magnet is moved, the position of which on the movement axis is to be detected by the Hall sensors (cf. 4 ). Depending on the position of the permanent magnet from the Hall sensors 2 Hall voltage generated is sent as an analog signal to the analog / digital converter inputs 4, 5 of the microprocessor 3 delivered. The microprocessor 3 generates an output signal from the two Hall voltages, for example by forming the difference from the absolute values of the two Hall voltages. This determined output signal is possibly processed further by the microprocessor depending on the respective programming and on a communication pin 17 issued. In the embodiment shown, the output signal subsequently passes through an RC filter 18 and an output amplifier 19 , which then the sensor signal on sensor output 13 provides.

In many applications, it is desirable if, in addition to the quasi-continuous sensor signal, a switching signal continues to be generated as soon as the determined path position reaches a predetermined threshold value. In simple cases, the predetermined position can be the end position of the movable permanent magnet. Appropriate programming (see below) allows the threshold value to be defined at any other point on the movement path. The switching signal is also from the microprocessor 3 generated and on a switching pin 20 issued. By a subsequent operational amplifier 21 and optionally a switching transistor 22 the signal characteristic is set to the desired values so that the switching signal ultimately at the switching output 12 is available.

In order to compensate for the non-linearities of the Hall sensors and, if necessary, to take into account assembly inaccuracies, a calibration of the displacement sensor is necessary. This can be done by recording the characteristic curve of the sensor and generating corresponding compensation values. For this purpose, a so-called look-up table is generated in a manner known per se, which is in the memory element 7 is filed. It is also desirable to adapt the sensor characteristics to the respective application cases, in that the sensor characteristic can be influenced by external specifications. In order to implement these functions, the microprocessor can be put into a programming mode, which in turn is subdivided into a calibration mode and a communication mode, for example. These two submodes differ only in terms of the functions and program sequences that are implemented by the microprocessor, the general functions being known to the person skilled in the art and not being explained in detail here.

• – Kennlinienkorrektur
• – Spannungskalibrierung
• – Stützstelleninterpolation
• – Definition von Schaltpunkten
• – Korrektur des Messbereichs (Spreizung)
• – Kommunikation mit einem Servicegerät.

The microprocessor is preferably programmed so that the sensor software can perform the following functions:

• - Characteristic curve correction
• - voltage calibration
• - node interpolation
• - Definition of switching points
• - correction of the measuring range (spread)
• - Communication with a service device.

In order for the circuit arrangement to be able to take up the programming mode even in the fully assembled state, the initialization of the programming mode and the communication with an external service device must be carried out via the available four-pin sensor connection 10 be made possible. For this purpose, a switchover potential is generated from the outside at the sensor output during an initialization routine 13 imprinted. The switching potential is from a voltage divider 23 processed and as a changeover signal to a mode selection input 24 of the microprocessor 3 placed, which is designed in the example shown as a third analog / digital converter input.

In 2 a program flow chart is shown, in which the most important steps are specified by the microprocessor 3 be carried out in the respective operating mode. The method, which is preferably implemented using appropriate software, starts in step 30. In step 31, the data stored there, in particular the look-up table, is read from the memory element (EEPROM). The calibration values are read in in the same way in step 32. During this initialization section, the microprocessor checks whether the circuit arrangement 1 via the sensor connector 10 a control or service device is connected, which in step 33 by querying the voltage potential at the sensor output 13 is realized. In the event that no service device is connected, the microprocessor continues its operation in the measurement mode, which starts in step 34. Within the measuring mode, for example, the values supplied by the Hall sensors are read in step 35 and the sensor signal in step 36 via the sensor output 13 output to the downstream circuit units.

In contrast, in step 33 the microprocessor determines that there is a switching potential at the sensor output 13 is present, he enters the programming mode in step 37. The programming mode is in turn divided into several subroutines in which, for example, new data are written into the memory element in step 38 or the Hall sensors are read out for calibration in step 39 and a voltage calibration is carried out.

Communication between the circuit arrangement is in programming mode 1 and a service device 40 required, whose block diagram in 3 is shown. As already explained, a voltage potential at the sensor output is used to initialize the programming mode 13 created with the sensor output 13 subsequently used for the bidirectional transmission of digital data to the microprocessor 3 on the communication pin 17 be fed. So that secure data communication can be carried out, a synchronization cycle is required for synchronization, which is between the circuit arrangement and the service device via the switching output 12 is exchanged. For communication between the circuit arrangement 1 and the service device 40 is again only the four-pole sensor connection 10 required. No other pins are required.

In the service device 40 becomes another microprocessor 41 used, preferably a PIC 16C876 is used. Via a synchronization pin 42 receives the microprocessor 41 the service device the clock signal from the circuit arrangement 1 , in which case the circuit arrangement of the displacement sensor works as a master device. In other embodiments, the master function could also be performed by the service device.

From a mode block 43 the required switching potential at the sensor output 13 supplied to switch between operating modes. Via a serial interface 44 can connect to an external personal computer 45 respectively. Preferably runs on this personal computer 45 software that provides the operator with a convenient user interface to use simple commands to operate the corresponding functions of the service device 40 to control and ultimately a programming of the circuit arrangement 1 to be able to make.

4 shows a simplified sectional view of a hydraulic valve arrangement 50 , which in addition to the actual hydraulic valve contains a circuit board (not shown) on which the circuit arrangement 1 is realized for the displacement sensor. The hydraulic valve has an actuator 51 which is along a movement axis 52 is slidably arranged. To control the flow rate of hydraulic fluid, the actuator 51 shifted, the driving force from an electrocoil 53 is delivered. A permanent magnet 54 is mechanical with the actuator 51 coupled so that the permanent magnet also along the movement axis 52 is moved and its position is representative of the position of the actuator. The position of the permanent magnet 54 is from the two Hall sensors 2 determined, which are also positioned in the housing of the hydraulic valve assembly. Finally, the hydraulic valve arrangement comprises the sensor connection 10 with the contacts already described 11 . 12 . 13 ,

Through the circuit arrangement explained above According to the invention, it becomes possible to use a displacement sensor with small size in that Integrate hydraulic valve, the required accuracies and linearities be made possible by a calibration of the displacement sensor. The overall size of the hydraulic valve is not due to additional connection elements enlarged since programming the circuit using the same four-pin sensor connection can be realized in the measuring mode for reading the sensor signals is needed.

Although the circuit arrangement according to the invention in connection with a hydraulic valve has been explained in more detail, the expert readily recognize that such a circuit arrangement generally can be used for the advantageous operation of displacement sensors, which Hall sensors use. With such displacement sensors can also other measurement and monitoring tasks solved become.

1 -

circuitry for the displacement sensor

2 -

Hall sensors

3 -

microprocessor

4 -

first Analog / digital converter input

5 -

second Analog / digital converter input

6 -

oscillator

7 -

storage element

10 -

sensor connection

11 -

Operating voltage connection

12 -

switching output

13 -

sensor output

15 -

voltage regulators

17 -

communication spin

18 -

RC filter

19 -

output amplifier

20 -

switch pin

21 -

operational amplifiers

22 -

switching transistor

23 -

voltage divider

24 -

Mode selection input

40 -

service equipment

41 -

microprocessor of the service device

42 -

synchronization spin

43 -

mode block

44 -

serial interface

45 -

personal computer

50 -

Hydraulic valve arrangement

51 -

actuator

52 -

motion axis

53 -

electric coil

54 -

permanent magnet

Claims (10)

Circuit arrangement ( 1 ) for a displacement sensor, which has two magnetic field sensors arranged parallel to a movement axis ( 2 ), the sensor voltages of which are linked to form an output signal, the circuit arrangement ( 1 ) a two-pole operating voltage connection ( 11 ), a switching output ( 12 ) and a sensor output ( 13 ) also has: - a microprocessor ( 3 ) which - in a measurement mode from each sensor ( 2 ) the sensor voltage at an analog / digital converter input ( 4, 5 ) receives, links them to the output signal and a sensor signal to the sensor output ( 13 ) and a switching signal to the switching output ( 12 ) supplies, and - in a programming mode via the switching output ( 12 ) and / or the sensor output ( 13 ) a bidirectional communication connection with an external service device ( 40 ) builds up to exchange data; - a switching element ( 23 ), which the voltage potential at the sensor output ( 13 ) and / or at the switching output ( 12 ) and if there is an external service device ( 40 ) embossed Switching potential to a switching signal to an operating mode selection input ( 24 ) of the microprocessor ( 3 ) which switches the microprocessor from measuring mode to programming mode; - a storage element ( 7 ), in which configuration data and possibly program commands are stored. Circuit arrangement according to Claim 1, characterized in that a voltage divider ( 23 ) which switches the changeover signal to a third analog / digital converter input ( 24 ) of the microprocessor ( 3 ) issues. Circuit arrangement according to claim 1 or 2, characterized in that the switching element ( 23 ) depending on the impressed switching potential, a two-stage switching signal to the mode selection input ( 24 ) of the microprocessor, whereby the microprocessor ( 3 ) is switched to either a calibration mode or a communication mode within the programming mode. Circuit arrangement according to one of claims 1 to 3, characterized in that in the programming mode the switching output ( 12 ) the transmission of a clock signal and the sensor output ( 13 ) serves the transmission of digital data. Circuit arrangement according to one of claims 1 to 4, characterized in that the two-pole operating voltage connection ( 11 ), the switching output ( 12 ) and the sensor output ( 13 ) in a four-pole sensor connection ( 10 ) are integrated. Circuit arrangement according to one of claims 1 to 5, characterized in that so-called as magnetic field sensors Hall sensors or magnetoresistive sensors can be used. Hydraulic valve assembly ( 50 ) with an electromagnetic actuator ( 53 ), along a movement axis ( 52 ) sliding actuator ( 51 ) and a displacement sensor, which has two magnetic field sensors arranged parallel to the movement axis ( 2 ) and a permanent magnet coupled to the actuator ( 54 ), whereby the sensors ( 2 ) delivered sensor voltages to a the position of the actuator ( 51 ) representing the output signal, characterized in that the hydraulic valve arrangement ( 50 ) furthermore a circuit arrangement ( 1 ) according to one of claims 1 to 6. Method for operating a displacement sensor, which has two parallel to a movement axis ( 52 ) arranged magnetic field sensors ( 2 ), a circuit arrangement ( 1 ) with a microprocessor ( 3 ), a switching element ( 23 ) and a storage element ( 7 ) and a two-pole operating voltage connection ( 11 ), a switching output ( 12 ) and a sensor output ( 13 ) has the following steps: - Query ( 33 ) at the sensor output ( 13 ) switching potential present during an initialization routine; - entering a measuring mode ( 34 ) or a programming mode ( 37 ), depending on the switching potential; - delivering a formed sensor signal to the sensor output ( 13 ) and a switching signal to the switching output ( 12 ) when a predetermined position of the actuator is reached ( 51 ) as long as the measuring mode ( 34 ) is active; - Exchange of data via the sensor output ( 13 ) and a communication cycle via the switching output ( 12 ) between the circuit arrangement ( 1 ) and a service device ( 40 ) as long as the programming mode ( 37 ) is active. The method of claim 8, wherein in the measurement mode ( 24 ) from each sensor ( 2 ) the sensor voltage is received and these are linked by forming the difference between the absolute values and the sensor signal. A method according to claim 8 or 9, wherein in programming mode via the sensor output ( 13 ) a bidirectional communication link with the external service device ( 40 ) is carried out for data exchange.