RU177150U1 - SPEED SENSOR - Google Patents

Abstract

The invention relates to devices forming an electrical signal with a frequency proportional to the speed of rotation of the gear on the shaft, and can be used in various industries to determine the speed of rotation of the shafts. The speed sensor comprises a housing, a magnetosensitive assembly with a magnetic system, a Hall sensor microcircuit, while the magnetic system is represented by an axially magnetized permanent magnet of cylindrical shape together with a magnetic field concentrator made of magnetically conductive steel located on the side of the working pole of the magnet and configured to partially exit the magnetic flux, an integrated active Hall sensor with a self-calibration function installed directly on the surface of the concentrator with an emphasis upper plastic lid. The technical result is an increase in sensitivity, improved thermal and vibration resistance of the speed sensor. 2 s.p. f-ly, 1 ill.

Description

The technical solution relates to devices that generate an electrical signal with a frequency proportional to the speed of rotation of the gear on the shaft, and can be used in various industries to determine the speed of rotation of the shafts, for example, in the automotive industry to determine the speed of a vehicle.

A known sensor for registering a ferromagnetic object (RU, 2244309, G01P 3/48, publ. 10.01.2005), comprising a non-magnetic body, magnetically sensitive node, consisting of an annular permanent magnet and a ferromagnetic core with a thread and a head.

The disadvantage of this design of the sensor’s magnetic system is that the ferromagnetic core requires an individual zero calibration, which is different for each sensor.

The prototype is a well-known sensor for registering a ferromagnetic object (RU 2284527, G01P 3/48, publ. 09/27/2006), in which there is a magnetically sensitive microcircuit and a permanent magnet (PM) in the form of a sleeve, at the zero point of which the microcircuit is placed. For the sensor to work, the microcircuit must be placed clearly in the zero zone of the PM, where the magnetic field induction does not exceed the microcircuit sensitivity threshold.

The proximity sensor works in conjunction with a ferromagnetic wheel and is designed to convert the rotation of the ferromagnetic wheel into electrical impulses, the frequency of which is proportional to the speed of the car.

The disadvantages of this device are:

- the need for individual calibration of the position of the Hall sensor in the magnetic system;

- lack of protection against deviations of the calibration parameters due to temperature and vibration influences;

- the use of a Hall sensor with severe restrictions on the level of hysteresis of magnetic induction.

The technical result of the utility model is to increase the sensitivity of the sensor, improving the thermal and vibration resistance of the speed sensor.

To achieve the claimed technical result, the following tasks are solved:

- changing the magnetic system of the sensor in order to increase the air gap between the sensor and the ferromagnetic wheel;

- simplification of the design of the sensor;

- implementation of the auto-tuning function of the sensor parameters.

The tasks are solved in that the design of the magnetic system of the magnetically sensitive assembly changes:

instead of a sleeve magnet, an axially magnetized magnet of a cylindrical type is used together with a concentrator of magnetically conductive steel. The hub is located on the side of the working pole of the magnet and has a special design with a partial output of magnetic flux. The chip is located directly on the surface of the hub. The position of the components of the magnetic system is ensured by the design of the holder, eliminating the possibility of their displacement ..

The design of the sensor is simplified by eliminating the metal cover requiring rolling. The used plastic cover acts as a holder and a limiter for the shift of the magnetic system and the printed circuit board.

The application of the proposed design with a magnetic hub and microcircuit provides the sensor with increased resistance to mechanical vibrations, shocks, external electromagnetic interference.

As a source of magnetic energy, it is possible to use highly coercive magnets such as hexaferrites, neodymium-iron-boron, samarium-cobalt, as well as magnetoplastics based on them.

The sensitivity of the speed sensor is increased through the use of an integrated active Hall sensor, which has a self-calibration function when turned on and during operation. The self-calibration function of the sensor allows you to level:

- scatter of the parameters of the magnetic system of sensors (from sensor to sensor);

- - temperature drift of the parameters of the magnetic system;

- fluctuations in the operating point of the sensor due to vibration and shock;

- changes in the parameters of the magnetic system during operation;

- change in the parameters of the sensor in the composition of the vehicle due to the action of magnetically conductive materials (magnetic chips, environmental details, etc.).

The active Hall sensor is connected to a printed circuit board, which may contain the following function blocks:

- duplication / inversion / signal schemes from the active Hall sensor;

- galvanic isolation;

- protection schemes against electromagnetic influences in the vehicle electrical system;

- frequency filter.

The utility model is illustrated by the following illustrations. FIG. 1 is a structural diagram of a speed sensor.

The vehicle’s speed sensor is used to register the rotation of a ferromagnetic gear wheel (1) mounted on a shaft and contains a metal housing (2), a magnetically sensitive assembly consisting of a permanent cylindrical magnet (8), a magnetic field concentrator (9), and an active Hall sensor (5) connected to a printed circuit board (7), which performs the function of matching signals with the electronics of the car, and connected via connectors (11) to the output contacts (4), rigidly fixed in the connector (3). At the same time, the elements of the magnetically sensitive assembly are fixed in the housing (2) with the holder (6), and, together with the printed circuit board (7), are filled with synthetic material (10), the holder (6) acts as a cover and, as a connector (3), is rolled in the housing for tightness.

The sensor works as follows:

The sensor is mounted perpendicular to the working surface of the registered ferromagnetic wheel having a tooth-cavity design. When the magnetic field changes due to the approach or removal of the ferromagnetic wheel, the active Hall sensor is triggered. When the “tooth” of the ferromagnetic wheel is located in the sensor sensitivity zone, the magnetic field induction at the positioning point of the active Hall sensor exceeds the value of _OR and the Hall microcircuit is in the “on” state. When the “cavity” of the ferromagnetic wheel is in the sensor sensitivity zone, the magnetic induction value Bt at the positioning point of the Hall microcircuit becomes lower than _OR and the microcircuit goes into the “off” state.

Thus, the implementation of the claimed utility model solves all the problems posed by the authors.

Claims (4)

1. The speed sensor, comprising a housing, magnetically sensitive node, with a magnetic system, a Hall sensor chip, characterized in that the magnetic system is represented by an axially magnetized permanent magnet of cylindrical shape together with a magnetic field concentrator made of magnetically conductive steel located on the side of the working pole of the magnet and configured to partially exit the magnetic flux, an integral active Hall sensor with a self-calibration function installed directly on the surface of the concentrator with emphasis on the upper plastic holder cover. 2. The speed sensor according to claim 1, characterized in that highly coercive permanent magnets such as hexaferrites, neodymium-iron-boron, samarium-cobalt, and magnetoplastics based on them are used as a source of magnetic energy. 3. The speed sensor according to claim 1, characterized in that the permanent magnet, holder, printed circuit board, hub, Hall sensor are flooded with a compound.

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