JPH0349367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a rotation sensor that detects the rotational position of an internal combustion engine.

(Prior art) Conventionally, this type of device has a sensor section in which a magnet and a Hall element serving as a magnetic detection element are arranged with a gap between them. Therefore, it has been common practice to detect the rotational position by blocking the magnetic flux supplied to the Hall element by the magnet.

However, in the conventional type described above, the gap between the sensor part needs to be wide enough to correspond to the thickness of the blade.
It is more difficult to apply sufficient magnetic flux to the Hall element than to a magnet, and this poses problems in terms of rotational position detection accuracy and miniaturization.

Therefore, conventional methods have been considered in which a magnet and a Hall element are arranged on one side of a rotating body made of a magnetic material having unevenness, and the magnetic circuit between the magnet and the Hall element is opened and closed as the rotating body rotates. (For example, Japanese Patent Application Laid-Open No. 145174/1983).

However, even in this case, there is a problem in that leakage magnetic flux of the magnet interlinks with the Hall element, making it impossible to obtain sufficient detection accuracy.

(Problems to be Solved by the Invention) Therefore, the present invention aims to reduce the size and improve detection accuracy.

(Means for Solving the Problems) Therefore, the present invention includes a magnet, an L-shaped magnetic body disposed on both sides of the magnet, and a magnetic detection element. A sensor section that forms a main magnetic path with one side open and a bypass magnetic path that is open on one side and bypasses the magnetic detection element with the magnet and the remaining part of the magnetic material; The present invention provides a rotation sensor comprising a magnetic rotating body that alternately faces open faces and open faces of a bypass magnetic path, and the sensor section is disposed on one side of the rotating body.

(Function) As a result, when the main magnetic path is formed, the bypass magnetic path is opened and sufficient magnetic flux is supplied to the magnetic sensing element, and when the main magnetic path is opened, the bypass magnetic path is formed and leakage magnetic flux to the magnetic sensing element is reduced. It can be suppressed.

(Example) Hereinafter, an example of the present invention shown in the drawings will be described. 1 and 2, the blade 2 fixed to the rotating shaft 1 has a window 7 and a protrusion 8.
The sensor section, which is located on the same circumferential angle and arranged on one side, is made of a resin molded material 6 in which a magnet 3, a Hall element 4, and an L-shaped magnetic bracket 5 are integrally molded.

In the rotational position shown in FIG. 1, the magnetic circuit through which the magnetic flux passes through the Hall element 4 is connected to the shaft 1.
The bracket 5 faces the window 7 of the blade 2 which rotates integrally with the Hall element 4, the bracket 5, the magnet 3,
A main magnetic path loop (dashed line in FIG. 1) passing through the protrusion 8 of the blade 2 is formed, and magnetic flux passes through the Hall element 4.

On the other hand, in the rotating element shown in FIG. 2, the magnetic circuit has a bypass magnetic path loop (broken line in FIG. 2) passing through the blade 2, bracket 5, and magnet 3, and almost no magnetic flux passes through the Hall element 4.

In this way, by arranging the sensor part on one side of the blade 2, air gap management is facilitated.
By making the blade shape such that magnetic flux is reliably passed through the Hall element 4 by the rotation of the blade, it is possible to downsize the device and improve signal accuracy.

FIG. 3 shows another embodiment of the present invention,
A blade 2 is arranged on the outer circumferential side of the sensor section.

Fig. 4 shows the sensor shown in Fig. 1 built into an ignition distributor, where 9 is a power distribution cap, 10 is a power distribution rotor, 11 is a centrifugal advance mechanism, 12 is a negative pressure advance mechanism, and 13 is a power distributor housing. It is.

In each of the embodiments described above, the main magnetic path and the bypass magnetic path are arranged in the axial direction of the shaft 1, but they may be arranged in the circumferential direction of the shaft 1. In this case, the blade 2 may be provided with only one of the window 7 and the protrusion 8.

Further, instead of the blades 2, a rotating body made of a magnetic material having uneven portions may be used.

Moreover, other magnetic detection elements such as a magnetoresistive element can also be used instead of the Hall element 4.

(Effects of the Invention) As described above, in the present invention, when the main magnetic path is formed, the bypass magnetic path is opened and sufficient magnetic flux is supplied to the magnetic detection element, and when the main magnetic path is opened, the bypass magnetic path is formed. Since leakage magnetic flux to the magnetic detection element is suppressed, the magnetic flux of the magnetic detection element is reliably interrupted as the rotating body rotates, which has the excellent effect of improving detection accuracy with a compact structure. . Furthermore, the sensor section includes a magnet, an L-shaped magnetic body placed on both sides of the magnet, and a magnetic detection element, and the magnet, a portion of the magnetic body, and the magnetic detection element form a main magnetic path with one side open. At the same time, since the magnet and the remaining part of the magnetic material form a bypass magnetic path that is open on one side and bypasses the magnetic detection element, it is possible to use a magnet with a complicated shape as in JP-A-57-189011. Another advantage is that there is no need to use an E-shaped one.

[Brief explanation of drawings]

1 and 2 are longitudinal cross-sectional views showing one embodiment of the sensor of the present invention at different rotational positions, FIG. 3 is a longitudinal cross-sectional view of another embodiment of the sensor of the present invention, and FIG. 4 is the same as that of the first embodiment. FIG. 2 is a longitudinal cross-sectional view showing an embodiment in which the illustrated sensor is built into an ignition distributor. 2...Blade forming a rotating body, 3...Magnet, 4...
Hall element forming a magnetic detection element, 5... magnetic bracket.

Claims (1)

[Claims] 1. A magnet, an L-shaped magnetic body arranged on both sides of the magnet, and a magnetic detection element, the magnet, a part of the magnetic body, and the magnetic detection element forming a main magnetic path with one side open. , a sensor section that is open on one side and forms a bypass magnetic path that bypasses the magnetic detection element by the magnet and the remaining part of the magnetic body; 1. A rotation sensor comprising: a magnetic rotating body that alternately faces open surfaces; and the sensor section is arranged on one side of the rotating body.