Sensor for measuring physical dimensions and process for balancing the sensor

• US 4,845,649 A
• Filed: 10/24/1988
• Issued: 07/04/1989
• Est. Priority Date: 12/19/1984
• Status: Expired due to Term

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Eckardt, Dieter, Schmid, Hans-Dieter, Hettich, Gerhard
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Trans, V. N.
• Application Number:
  US07/262,079
• Time in Patent Office: 253 Days
• Field of Search: 364/556, 364/558, 364/571.01, 364/551, 364/571.02, 73/12, 73/146.2, 73/146.5, 73/146.8, 140/52 R, 140/52 F, 140/501, 140/517, 140/521
• US Class Current: 702/104
• CPC Class Codes: B60C 23/043 using transformer type signal transducers, e.g. rotary transformers
• CPC Class Codes: B60C 23/0471 System initialisation, e.g. upload or calibration of operating parameters
• CPC Class Codes: B60C 23/0479 Communicating with external units being not part of the vehicle, e.g. tools for diagnostic, mobile phones, electronic keys or service stations
• CPC Class Codes: G01D 3/022 having an ideal characteristic, map or correction data stored in a digital memory
• CPC Class Codes: G01L 27/005 Apparatus for calibrating pressure sensors

Abstract

A sensor is suggested for measuring physical dimensions as well as a method for balancing its measuring values, whereby an evaluation circuit is used for the calculation of the accurate measuring value. The sensor (10) is combined with a PROM (15) into a structural unit (19), whereby the correction values for the measuring signals of sensor (10) are stored in PROM (15). Sensor (10) and PROM (15) have at least one output (18) through which the measuring signals as well as the correcting data have to be transmitted to evaluation circuit (30).

Claims

1. Sensor arrangement for measuring physical quantities and transmitting electric signals depending on the measured quantity, comprising a sensor for generating measuring signals corresponding to a measured physical quantity;

an energy store;

an A/D convertor connected to the sensor;

a programmable non-volatile storage for storing a mathematical code for computing a set of correction data correlated to the measuring signals of the sensor for a predetermined number of states of the physical quantity;

a logic circuit having one input connected to said A/D convertor, another input connected to said storage and a serial data input/output;

said sensor, A/D convertor, energy store, non-volatile storage and logic circuit being mounted on a common plate to form a single structural unit wherein said serial data input/output is connected as an input for control commands to said logic circuit and for supplying said energy store; and

said logic circuit directing, in response to corresponding control commands, the measuring data from said A/D and the matematical code from said storage to said data output.

2. Sensor arrangement as defined in claim 1 wherein said serial data input/output is connected to an evaluation circuit for receiving said measuring data and said mathematical code, computing from said mathematical code a set of correction data correlated to the measuring data for a predetermined number of test states of the measured quantity, and evaluating the measuring data according to corresponding correction data.

3. Method in accordance with claim 2, wherein the correcting values which are successively determined by the adjustment circuit are at first temporarily stored in an intermediate storage and subsequently written into the non-volatile storage of the structural units.

4. Sensor arrangement in accordance with claim 2, wherein said serial data input/output is connected to a transmitter coil which is inductively coupled with a further transmitter cil being connected with the evaluation circuit.

5. Sensor arrangement in accordance with claim 4, wherein the structural unit is disposed on a vehicle wheel in such a manner that during ech full wheel rotation the first mentioned transmitter coil is located opposite the further transmitter coil which is stationary and disposed in proximity of the wheel.

6. Method of correcting measuring values of signals transmitted from a sensor of a physical quantity, comprising the steps of

(a) mounting on a common plate a sensor, a PROM, an energy store, an A/D convertor connected to said sensor, a logic circuit having a serial data I/O terminal and being connected for directing energy from said I/O terminal to said energy store and therefrom to said A/D convertor and said PROM, and further directing data from said A/D convertor and said PROM to said I/O terminal;

(b) temporarily connecting said PROM and said serial data I/O terminal to an adjusting circuit;

(c) measuring by said sensor a succession of predetermined test states of said physical quantity;

(d) comparing in said adjusting circuit the actual measuring values of the sensor signals transmitted at the respective test states with nominal values corresponding to the respective test states of the physical quantity, and determining the deviations of successive actual measuring values from the nominal ones;

(e) storing the successive deviations as correction values in said PROM, and permanently disconnecting said PROM and said serial data I/O terminal from said adjusting circuit; and

(f) connecting said serial I/O terminal to an evaluation circuit for receiving measuring data from said A/D convertor and corresponding correction data from said PROM, and evaluating the measuring data according to the correction data.