Electricity: measuring and testing – Magnetic – Displacement
Patent
1997-07-09
2000-03-28
Strecker, Gerard
Electricity: measuring and testing
Magnetic
Displacement
307116, 3242072, 324235, 361180, H03K 1795, H01H 3600, G01B 714
Patent
active
060436468
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a proximity switch having a magnetic field-sensitive sensor.
Conventional mechanical switches are increasingly being displaced, in particular in motor vehicle applications, by non-contacting proximity switches having a magnetic field-sensitive sensor, for example a Hall sensor or a magneto resistor. In principle, Hall sensors are composed of a semiconductor layer, in particular one made of silicon, which is supplied with a constant current. The constant current is influenced by a magnetic field component at right angles to the layer and the sensor supplies a Hall voltage which may be evaluated and which is proportional to the applied magnetic field strength. At present, Hall sensors are expediently used in the form of an integrated circuit which already contains an evaluation circuit which is suitable for evaluating the switching state.
2. Description of the Prior Art
German Offenlegungschrift 39 01 678 discloses positioning the magnetic field-sensitive sensor in a magnetic field-free zone of a special permanent magnet arrangement. In order to achieve a high temperature stability, the permanent magnet in the known proximity switch is therefore configured in such a way that an annular pole surface results. In this case, driving by a flat ferromagnetic triggering part is carried out at right angles to the pole plane, the magnetic field-free zone not being canceled when the triggering part is brought close but only when moving away from the sensor.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a proximity switch having a magnetic field-sensitive sensor which is particularly simply constructed and is very simple to produce.
According to the invention, this object is achieved by a proximity switch having a magnetic field-sensitive sensor, magnetization, is fitted, being formed between the limbs of the U by three like, mutually repelling poles, above the limbs of the U in a plane parallel to the base of the U, and wherein the cancellation of the magnetic flux-free region when the triggering part is brought close to the two poles of the limbs of the U.
The invention is explained in further detail below with reference to an exemplary embodiment represented in the single FIGURE of the drawing.
BRIEF DESCRIPTION OF THE DRAWING
The FIGURE shows, in a side view, a magnet system of a proximity switch according to the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A U-shaped magnet 10 with a vertical direction of magnetization is represented in the FIGURE. Flux lines are shown at 9. There is a magnetic flux-free region 11 between the limbs 10A and 10B of the U, since the three north poles repel one another. A magnetic field-sensitive sensor 12 is fitted in this region 11. When a ferromagnetic triggering part 14 is brought close to the U-shaped magnet 10, above the magnet, in the plane indicated, the two lateral north poles are partly shielded or their magnetic field is deflected. The magnetic flux of the central north pole is then able to penetrate better, that is to say it flows through the magnetic field sensor 12 and thus triggers a switching signal.
The rectangular flux-free region 11 shown in the drawing figure has a longitudinal extent (horizontal in the drawing) which is substantially perpendicular to a magnetic pole axis (vertical axis running through N and S poles in the drawing) of each of the limbs.
The arrangement represented is particularly simply constructed and space-saving. It is also advantageous that shielding of the sensor from three sides results from the particular geometric configuration of the magnet system. A reduced magnetic susceptibility to faults of the sensor is of significance, for example in the case of applications of the proximity switch in motor vehicle central locking systems.
A switch which was constructed by way of a trial already had a switching distance of 1.5 mm given dimensions of in each case 4 mm for the thickness of the magnet and for the width of the limb
REFERENCES:
patent: 3226631 (1965-12-01), Kuhrt et al.
patent: 4086533 (1978-04-01), Ricouard et al.
patent: 4524932 (1985-06-01), Bodziak
patent: 4618823 (1986-10-01), Dahlheimer et al.
patent: 4712064 (1987-12-01), Eckhardt et al.
patent: 4745363 (1988-05-01), Carr et al.
patent: 4992731 (1991-02-01), Lorenzen
patent: 5137677 (1992-08-01), Murata
patent: 5210489 (1993-05-01), Petersen
patent: 5450009 (1995-09-01), Murakami
Siemens Aktiengesellschaft
Strecker Gerard
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