JPS58122403A - Position detector - Google Patents

Abstract

PURPOSE:To obtain detection sensitivity which is less influence by temperature and clearance by fitting a magnet and a magnetism sensing element to one side of an L-shaped magnetic circuit, providing the 2nd magnet to the other side, and applying the magnetism sensing element with a magnetic field which is zero or negative while magnetism is not detected. CONSTITUTION:The magnetism sensing element 2 and magnet 4 are fitted to the horizontal part and vertical part of the L-shaped magnetic circuit 1 and the magnet 5 is fitted to the opposite back side. Magnetic fields to be applied to the element 2 by pieces of magnetic flux by the magnets 4 and 5 are denoted as phi1 and phi2. When there is no body 3 to be detected, those magnetic fields to the element 2 are balanced completely or in a slidghtly negative state to obtain an initial condition shown in a figure A. When the body 3 to be detected is put closer, phi1>phi2 and a high value is obtained as shown in a figure B. With such a slice level that the magnetic fields are nearly balanced, the output voltage of the element 2 is 0 and a little influence of temperature is exerted. In this case, the zero magnetic field point is close to the value of the magnetic field A of the element 2 when there is no body to be detected, and the influence of clearance is hardly exerted. Thus, stable detection sensitivity is secured.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position detection device used for detecting the crank angle of an internal combustion engine, and in particular uses a magnetically sensitive probe such as a Hall element to utilize changes in magnetic flux depending on the presence or absence of an object to be detected. Concerning position detection.

Conventionally, as this type of position detection device, for example,
There is a prior art disclosed in Japanese Patent No.-108431. As shown in Fig. 1, both ends of a C-shaped magnetic circuit 1 have magnetic poles 1a and 1b magnetized to N and S, and a magnetic cord 2 is inserted between these magnetic poles 1a and lb. are installed to form the detection section, and magnetic poles 1a, 11+ and 1m magnetic poles f21. The object to be detected 3 approaches or moves away from one opposing position with a predetermined clearance d.

When the object to be detected is not detected (+) in Fig. 2, the magnetic flux of the magnetic poles 1a and ib is reduced to the solid line in Fig. 2(b) from N through the magnetic cable 2. Flows to S, Zono i
ll&Magnetic element 2 is kept under a strong magnetic field as shown at A in Figure 3. On the other hand, as the object to be detected approaches,
At the time of detection, the object to be detected 3 is at the magnetic pole +a.

By approaching the pole 1b, the magnetic flux from the magnetic pole 1a is bypassed to the detection target 3 side, and at the magnetically sensitive tree r2, the value of the magnetic field is reduced to a polar value as shown in 8 in Fig. 3. . Then, by periodically moving the detection target 3 toward and away from the object 3, the above-mentioned action is carried out in the alternation 13, and the magnetic field applied to the magnetically sensitive element 2 is continuously changed as shown in the curve in FIG. The rotational position of the object to be detected is detected by slicing it at a predetermined magnetic field level C.

By the way, in such a configuration, when the magnetic flux passing through the sensing element 2 decreases when the sensing object approaches, the magnetic flux decreases due to a change in the clearance d between the sensing object and the sensing object due to manufacturing errors, vibrations, etc. Since the magnetic field 13 of 2 fluctuates as shown in Fig. 3, the slice level 0 needs to be set higher than that by taking into account the fluctuation of the magnetic field B. In general, the sensitivity of the magnetic field 2 is higher than that of the magnetic field 13 of the magnetic field B. changes, so due to such a lagoonal change, the magnetic fields A and B of the magnetic sensing element 2
It will be in a state where it fluctuates 4. Therefore, if we consider this sudden movement due to temperature, it becomes difficult to set the above-mentioned slicing level C to an immovable spear, and for this reason, it is necessary to increase the precision of the clearance and manage the temperature sufficiently. There are drawbacks.

The present invention was developed in view of the above circumstances. Also, focusing on the fact that the point of zero magnetic field is less affected by the concentration and GJ, taking this into account, the -C configuration allows detection sensitivity with less influence of clearance and magnetic field. The purpose is to provide a position detection device (to obtain the desired location).

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be specifically described below with reference to the drawings. In Fig. 4, it is an L-shaped magnetic circuit, and a magnetic sensing element 2 is attached to the tip of the underwater part of the magnetic circuit 1, and the magnetic circuit 1 is located far away from the magnetic sensing element f2.
At the vertical part of the magnetic circuit 1, the magnet 04 of N and S is placed in the same position as the magnetic sensing element 2 (J 4J T, at a certain 9°). Attach another N to the R part on the side.
, S magnet 5 is taken (-I GJ), and the detection part is configured, and in this case, the detection object 3 approaches or approaches the position facing the magnetically sensitive sf2 magnet 4 with a predetermined clearance d by rotation. It has become (Y゛).

At this point, the magnet 4 has the S pole on the magnetic circuit 1 side and the N pole on the detection object 3 side. It returns to the magnet 4 via the magnetic circuit 1. -h, It1 stone 5 has the magnetic circuit 1 side set as N pole, and the magnetic flux from this magnet (15) passes through the magnetic circuit 1 and enters the magnetic sensing element 2 in the opposite direction to the magnetic flux from the above-mentioned Wa 64, and then enters the air. Take it back to the eaves (lids)→
I'm being kicked.

Great magnet 1. -+ Let φ1 be the magnetic field that is caught in the magnetic flux from 4 and attached to the magnetic sensing cable I2, and φ2 is the magnetic field that is applied to the magnetic sensing system O'2 by the magnetic flux from the magnetic 65. The magnetic field detected by the magnetic element 2 is so balanced that zero Jk is slightly negative.

Since the present invention is configured as described above, the present invention is as shown in FIG. 5 (91).
), when the detection target 3 is far away, the magnetic 4i
Under the initial conditions 4 and 5, the magnetic field of the magnetic sensing element 2 becomes zero or slightly negative as shown in FIG. Next, as shown in FIG. 5(b), when the detection object 3 approaches the magnet 4 and the ldl magnetic element 2 and positions them oppositely, the detection object 3 bridges between the magnet 4 and the magnetic sensing element 2. Then, magnet 4
A large amount of magnetic flux passes through the detection object 3, the l1f1 magnetic element 2, and the magnetic circuit 1.

The magnetic field in this magneto-sensitive element 2 is reversed to φ1)φ2,
6th W [Slight change in clearance like 3.

Even if there is some variation, the value will be high. And like this °
By doing these things periodically and alternately, the magnetic field of the magnetically sensitive element 2 changes like the curve shown in FIG. 6 and always passes through the point of zero magnetic field.

For example, when a small loop lkf is used as the magnetically sensitive element 2, the sensitivity changes depending on #A, and the output voltage at zero magnetic field becomes zero and is not affected by temperature. [''k (i.

Further, this point of zero magnetic field is very close to the value of the magnetic field A of the magnetic sensing element 2 when there are four objects to be detected, and is not easily affected by clearance. Therefore, by setting the slice level near such a zero magnetic field, stable detection sensitivity can be ensured without being affected by clearance fluctuations or temperature changes, allowing accurate position detection of the object to be detected. However, according to the present invention, the magnet 4.5 can be used to sense any bias magnetic field, although some magnetoresistive elements have poor sensitivity near zero magnetic field and require a bias magnetic field. In particular, there are no restrictions on the magnetically sensitive cable 2.

FIG. 7 shows another embodiment in which a large number of second magnets 65 are arranged for the first magnet 4. In this case, in a non-detection state where the detection target 3 is far away, all the LADs are arranged so that the magnetic field generated by the magnetically sensitive main f2k is negatively balanced to zero or IM.
By doing this, the same effect as in the first embodiment can be obtained.Also, by using the second rut: i5, the magnetic flux density applied to the magnetically sensitive cable f2 can be adjusted. Since it is possible to obtain a detection sensitivity of fr M*, there is no manufacturing error.

k&! There is an advantage that it is possible to easily deal with the influence of changes in the clearance d due to I < i.

As is clear from the explanation below, according to the present invention, the magnetic circuit,
A magnetic sensing element is arranged with a plurality of magnets, and is configured to operate in such a way that it collapses the magnetic field of the magnetic sensing cable 2 when an object to be detected approaches, and the slice level is set near zero magnetic field to reduce clearance and Since the position can be detected accurately without being affected by humidity, there is no need to manage clearance or humidity, and it is easy to set the suit chair level. It has excellent sensitivity to smallpox detection, does not require the shape of the detection part to be unobtrusive, and is very compact, making it especially suitable for use as the magnetically sensitive probe 2.

[Brief explanation of drawings]

Fig. 1 shows an example of a conventional position detection device; Fig. 2 (a) and (b) show presence/absence of detection states; Fig. 4 shows a characteristic line; Fig. 4 5 is a plan view showing an embodiment of the position detection device according to the present invention, FIGS. FIG. 4 is a small plan view of another embodiment of position detection fi@. DESCRIPTION OF SYMBOLS 1...Magnetic circuit, 2...Magnetic sensing element, 3...Detection object, 4.5...Magnet. Patent applicant Fuji Heavy Industries Co., Ltd. Representative Patent Attorney Jundo Kobashi Patent Attorney Susumu Murai

Claims (1)

[Claims] A first magnet and a magnet are placed apart from each other on one side of the magnetic circuit, and at least one or more second fibers are placed on the other side.j1. [With the first magnet! A detection target is brought close to or Ml [at a position facing the JIA magnetic element, and when the detection target is separated and is not detected, L is set by the first and second magnets.
A position detection device characterized in that the magnetic field applied to the sensing magnetic cord is balanced in a predetermined ring.