JPH0682204A - Vehicle height detector - Google Patents

Abstract

PURPOSE:To improve carrying property and reliability of wiring by incorporating a magnetic reading section into a rod of a cylinder concerning a vehicle height detector which is provided integrally with a shock absorber to detect the elongation thereof in non-contact. CONSTITUTION:A sensor section 9 comprising a magnetic 9a and a Hall element 9b is built in a rod 4 of a shock absorber 1. On the other hand, a magnetic scale 10 comprising magnetic body 10a and a non-magnetic body 10b connected successively at a specified pitch is provided on an internal wall 3 of the shock absorber 1. The Hall element 9b detects a vertical component alone of a magnetic flux generated toward the magnetic body 10a from the magnet 9a, thereby, detecting a magnetic flux oscillating with the movement of the rod 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle height detecting device, and more particularly, to a vehicle height detecting device which is provided integrally with a shock absorber and detects expansion and contraction of the shock absorber in a non-contact manner.

[0002]

2. Description of the Related Art Conventionally, as a device for measuring the amount of displacement of a cylinder, there is known a device in which a magnetic scale is provided on a rod of the cylinder and a magnetic reading section is arranged on the cylinder. -30602 publication).

In the apparatus described in the above publication, the magnetic scale is constructed by alternately magnetizing the rods to the N pole and the S pole. Further, the magnetic reading unit is arranged at a position where the magnetism generated by this rod can be detected.

For this reason, when the cylinder expands and contracts, the relative positional relationship between the rod and the magnetic reading portion changes, and the magnetic reading portion detects magnetic flux whose directions are alternately reversed. Therefore, the device described in the above publication measures the displacement amount of the cylinder by counting the number of inversions.

[0005]

However, in the above-mentioned conventional apparatus, it is necessary to provide the magnetic reading section on the cylinder. Therefore, if this device is incorporated into a shock absorber and is applied to a vehicle height sensor, it is necessary to secure a space for the magnetic reading unit on the cylinder.

Generally, the shock absorber is used with the rod fixed to the vehicle body side and the cylinder fixed to the wheel side. Therefore, when the above-mentioned conventional device is incorporated, the magnetic reading portion is arranged at a portion whose position is relatively changed with respect to the vehicle body, and it becomes necessary to provide wiring between the non-fixed portions.

As described above, the vehicle height detection device in which the above-described device is applied to the shock absorber has a problem that the mountability on the vehicle body is poor and the reliability of the wiring portion is difficult. There is.

The present invention has been made in view of the above points, and improves the mountability and the reliability of wiring by incorporating a magnetic reading unit in the rod of the cylinder and providing a magnetic scale on the inner wall of the cylinder. It is an object of the present invention to provide a height sensor for a vehicle.

[0009]

SUMMARY OF THE INVENTION The above-mentioned problems are composed of a plurality of magnetic bodies and non-magnetic bodies which are alternately arranged, and are provided on a magnetic scale provided on the inner wall of the cylinder and a rod of the cylinder. A magnetic field generating means, and a directional magnetic sensitive element that is movable integrally with the magnetic field generating means and that detects only the vertical component of the magnetic flux that the magnetic scale receives from the magnetic field generating means, depending on the vehicle height, This is solved by a vehicle height detection device that detects the vehicle height by detecting the relative movement of the rod with respect to the cylinder.

[0010]

The magnetism generating means of the vehicle height detecting device having the above structure emits a magnetic flux only toward the magnetic body portion of the magnetic scale. Therefore, when the magnetism generating means and the magnetic body portion of the magnetic scale are opposed to each other, a vertical magnetic flux is generated between them.

From this state, when the cylinder expands and contracts and the relative positional relationship between the rod and the magnetic scale changes, the perpendicular magnetic flux tilts. That is,
The vertical component of the magnetic flux emitted from the magnetism generating means toward the magnetic scale is reduced.

Therefore, the magnetic flux detected by the directional magnetic sensing element is strengthened or weakened as the cylinder expands and contracts. Therefore, the vehicle height detection device having the above-mentioned configuration can detect the expansion and contraction of the cylinder with high accuracy while being completely built in the cylinder.

[0013]

[Embodiment] Next, the structure of a vehicle height detecting device according to the present invention will be described.
For the sake of clarity, description will be given based on appropriate examples.

FIG. 1 is a block diagram of an embodiment of a vehicle height detecting device according to the present invention, and FIG. 2 is an overall view of a shock absorber incorporating the device of this embodiment. 1 and 2
In, the same parts are denoted by the same reference numerals.

In the drawings, reference numeral 1 indicates a two-cylinder shock absorber, and reference numerals 2 and 3 indicate shock absorbers 1.
The outer cylinder and inner cylinder of FIG. Inside the inner cylinder 2, a rod 4 made of a non-magnetic material and an oil 5 that determines the damping characteristic of the shock absorber 1 are inserted.

A rod end 6 is provided at the lower end of the rod 4. The rod end 6 is provided with an orifice having a predetermined diameter, and when the oil 5 passes through this orifice, a damping force is generated between the rod 4 and the inner cylinder 3.

Both upper open ends of the outer cylinder 2 and the inner cylinder 3 are closed by an absorber cap 7. A base valve 8 is arranged at the lower open ends of the outer cylinder 2 and the inner cylinder 3. The base valve 8 has a space inside the inner cylinder 3,
The damping characteristic of the shock absorber 1 is determined by having an orifice having a predetermined diameter that connects the space surrounded by the outer cylinder 2 and the inner cylinder 3 to each other.

By the way, as shown in FIG. 1 and FIG.
The vehicle height detection device according to the present embodiment includes a sensor unit 9 built in the rod 4 and a magnetic scale 10 provided at a predetermined position of the inner cylinder 3. Note that FIG. 1B shows an enlarged view of the sensor unit 9 and the magnetic scale 10.

As shown in FIG. 1B, the sensor unit 9 is
It is composed of a magnet 9a corresponding to a magnetism generating means and a hall element 9b corresponding to a directional magnetic sensitive element. The sensor unit 9 is arranged inside the rod 4 made of a non-magnetic material as described above. Further, the magnetic scale 10 is provided in a part of the inner cylinder 3, and the magnetic bodies 10 a and the non-magnetic bodies 10 are alternately arranged in the moving direction of the rod 4.
b.

The reason why the sensor unit 9 has the above-mentioned structure in the apparatus of this embodiment will be described below with reference to an example of an improper structure shown in FIG. In addition, in FIG.
The same parts as those in FIG. 2 are designated by the same reference numerals and the description thereof will be omitted. Here, FIGS. 3A and 3C are
The front view of this comparative example is shown and FIG. 3 (B) is the same figure (A).
The BB cross section in the inside is shown.

As shown in FIG. 3B, in this comparative example of the vehicle height detecting device, the sensor portion is composed of a magnet 11, a hall element 12 and yokes 13 to 15. This configuration is used for the magnetic substance 1 of the sensor unit 16 and the magnetic scale 10.
This is a structure for forming a magnetic loop shown by a broken line in the figure when 0a and 0a face each other.

That is, the magnetic force line emitted from the N pole of the magnet 11 is passed through the rod 4, which is a non-magnetic body, the air gap between the sensor unit 16 and the magnetic scale 10 and the S pole of the magnet 11 through the magnetic body 10a. It is a structure for refluxing.

Further, the yokes 13 to 15 are members provided so that the magnetic flux emitted from the magnet 11 effectively draws a loop, and are members widely used conventionally in such a magnetic circuit. .

However, in order to use it as a shock absorber, an oil passage 17 (0.3 ± 0..3) for passing the oil 5 is provided between the rod 4 and the magnetic scale 10.
2 mm) must be provided. Further, considering the space (1.5 mm) provided between the yokes 13 and 14 for incorporating the Hall element 12 and the wall pressure (0.5 mm) of the rod 4, a minimum of 3 is included in this magnetic circuit. A gap of 0.5 mm will result.

Therefore, the magnetic lines of force around the magnet 11 are short-circuited around the magnet 11 as shown in FIG. 3C, and even if the sensor portion 17 faces the magnetic body 10a at a distance, the holes are generated. The magnetic flux penetrating the element 12 becomes an extremely small magnetic flux.

FIG. 4 is a diagram for explaining another drawback of the vehicle height detecting device having the above-mentioned structure. FIG. 7A shows a case where the width of the sensor unit and the width of the magnetic body 10a of the magnetic scale 10 are almost the same, and FIG. 7B shows the case where the magnetic force output from the sensor unit is increased. , Magnet 11 and yoke 13
15 to 15 and the case where the width of the Hall element 12 is increased. In addition, the arrow in each figure shows the magnetic force line emitted from the magnet 11.

As described above, in the vehicle height detecting device shown in FIG. 4, the yoke 14 is provided between the Hall element 12 and the magnetic scale 10. Therefore, the magnetic force lines emitted from the magnet 11 travel substantially perpendicular to the magnetic scale 10 until they pass through the yoke 14.

That is, as shown in FIG. 4 (A), whether the sensor portion 15 faces the magnetic body 10a of the magnetic scale 10 in a spaced manner or the non-magnetic body 10b in a spaced manner, the Hall element 12 is not attached. Since the magnetic flux that penetrates is small, there is almost no difference between the two magnetic fluxes.

In order to make the difference, FIG.
When the width of the magnet 11 or the Hall element 12 is widened to increase the magnetic flux penetrating the Hall element as shown in (B), the sensor section 15 faces the plurality of magnetic bodies 10a and nonmagnetic bodies 10b at the same time. become. Therefore, although the magnetic flux penetrating the Hall element 12 increases, the sensor unit 15 cannot read the position of the magnetic scale.

For this reason, in the apparatus of this embodiment,
As described above, the Hall element 9b and the magnetic scale 10
A magnetic material such as a yoke is not interposed between the Hall element 9b and
The width of the magnet 11 is widened until the desired magnetic flux is obtained, while keeping the width of the magnet substantially the same as the width of the magnetic body 10a.

FIG. 5 is a diagram showing the state of magnetic force lines emitted from the magnet 9a of the apparatus of this embodiment toward the magnetic scale 10. The principle of the sensor unit 9 of the apparatus of this embodiment reading the position from the magnetic scale 10 will be described below with reference to FIG. In the figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 5, in the apparatus of this embodiment, the magnetic force lines emitted from the N pole of the magnet 9a are directed substantially linearly to the magnetic body 10a of the magnetic scale 10. Further, as described above, the width of the Hall element 9b is narrower than the width of the magnet 9a. Therefore, in the case where the Hall element 9b faces the non-magnetic body 10b with a space as shown in FIG. 5 (A), and in the case where the Hall element 9b faces the magnetic body 10a with a space as shown in FIG. 5 (B), A difference occurs in the direction of the magnetic flux penetrating the Hall element 9b.

That is, the Hall element 9b is the non-magnetic material 10
Of the magnetic body 1 located on both sides of the non-magnetic body 10b, the magnetic flux generated from the magnet 9a is opposed to the central portion of the non-magnetic body 10b.
Since the light travels toward 0a, it is obliquely incident on the Hall element 9b. On the other hand, when the Hall element 9b is opposed to the magnetic body 10a with a space therebetween, the magnetic flux generated from the central portion of the magnet 9a penetrates the Hall element 9b vertically and is incident on the magnetic body 10a which is directly separated with a space. .

Further, the Hall element 9a has a property of detecting only the component perpendicular to itself in the magnetic flux penetrating itself. Therefore, the Hall element 9b is made of the non-magnetic material 10b.
If the Hall element 9b is opposed to the magnetic body 10a.
The detected magnetic flux is smaller than that in the case where the magnetic flux is opposed to.

FIG. 6A shows the sensor unit 9 of the apparatus of this embodiment.
6 shows a voltage waveform output from the Hall element 9b when the is moved along the magnetic scale 10. The device of this embodiment uses the existing hall element in order to realize the vehicle height detection device at low cost. The Hall element 9b has a sensitivity of converting the magnetic flux density of 1 kGs into 100 mV and outputting it.

FIG. 6B is a diagram showing the breakdown of the magnetic flux detected by the Hall element 9b. As shown in the figure,
The magnetic flux detected by the Hall element 9b includes magnetic noise of about 50 Gs and temperature characteristic of about 15%. still,
This temperature characteristic component is the temperature characteristic component of the magnet 9a (about 4.8).
%) And the temperature characteristic component of the Hall element 9b (about 9.6%).

By the way, when the expansion / contraction length of the shock absorber is detected by using such a vehicle height detecting device, the output waveform shown in FIG. 9A is binarized by the electronic control unit to obtain the peaks or valleys of the waveform. Need to count. Therefore, it is required that the effective component of the voltage waveform output from the vehicle height detection device (amplitude a in FIG. 7A) has a width that can be binarized by the electronic control device.

Generally, the amplification factor limit for amplifying the sensor output voltage to a practical level is about 100 times. This is because, when an amplification factor exceeding 100 times is used, the accuracy of the output waveform after amplification is significantly deteriorated, or an expensive filter or the like is required to maintain the accuracy.

That is, the smaller the amplification factor for reading the sensor output by the electronic control unit, the more advantageous in terms of detection accuracy and cost. Further, conventionally, there is a track record of amplifying the output of a hall element by 30 times as an in-vehicle sensor. Therefore, in the device of this embodiment, the amplification factor of the output of the Hall element 9b is set to 30 times.

By the way, in order to determine the threshold level in the electronic control unit of the system to which the device of this embodiment is applied, it is necessary that the effective amplitude after amplification is 1 V or more. That is, the effective amplitude before amplification is 1 V / 30≈33.
4 mV or more, that is, the effective component of the magnetic flux detected by the Hall element 9b is required to be 334 Gs or more.

As described above, the magnetic flux detected by the Hall element 9b contains an ineffective component consisting of magnetic noise of 50 Gs and a temperature characteristic of 15%. Therefore, the amplitude ΔB of the magnetic flux to be detected by the hall element 9b is (334 + 5)
0) * (100 / (100-15)) = 457.6 Gs or more. Therefore, in this embodiment, ΔB is 500
It is set to Gs or higher.

FIG. 7 is a diagram showing in detail the main parts of the apparatus of this embodiment. Hereinafter, the magnitude of ΔB in the apparatus of this embodiment will be described with reference to FIG. In the figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted.

As shown in FIG. 7, the gap between the Hall element 9b and the magnetic scale 10 is the rod 4 (Max
0.5 mm) and the dimensions of the oil passage 17 (Max 0.5 mm) show that the maximum is 1.0 mm. In this case, since the Hall element 9b is fixed to the magnet 9a, the thickness of the printed circuit board (not shown) is restricted, so that the magnet 9a and the magnetic scale 10 may be fixed.
The maximum gap is 2.0mm.

The magnetic scale 10 is a magnetic body 1 having a width of 1 mm.
0a is embedded in a non-magnetic material 10b such as stainless steel with a pitch of 3 mm, that is, a pitch of 4 mm. Further, as the magnet 9a, a magnet whose maximum value Φ of the magnetic flux detected by the hall element 9b is 3.7 kGs or more is used.

First, ΔB in the case where the sensor portion 9 is at a position as shown in the figure, that is, when the Hall element 9b is opposed to the central portion of the non-magnetic body 10b at a distance will be described. As described above, the magnetic force lines emitted from the magnet 9a toward the magnetic scale 10 are directed almost straight toward the magnetic body 10a. Therefore, the magnetic force line penetrating the Hall element 9a has an incident angle of θ with respect to the Hall element 9a.

That is, in this case, the magnetic field B ₁ detected by the Hall element 9a becomes a vertical component of the magnetic flux penetrating the Hall element 9b and is represented by B ₁ = Φ * sin θ. Where ta
Since nθ = (gap / (3/2)) = 4/3, sin θ = 0.8. From this, B ₁ = 3.7 kG
It becomes s * 0.8 = 2.96 kGs.

Next, considering the case where the Hall element 9b is opposed to the magnetic body 10a of the magnetic scale 10 with a distance, the magnetic flux B ₂ detected by the Hall element 9b is the maximum of the magnetic flux detected by the Hall element 9b. Since it is a value, it is 3, 7 kG
s.

Therefore, ΔB in the apparatus of this embodiment is B
A ₁ -B ₂ = 740Gs. This value is a value sufficiently larger than the required value of 500 Gs from the electronic control unit described above. Therefore, according to the vehicle height detecting device of the present embodiment, when the shock absorber 1 expands and contracts, a sufficiently readable voltage waveform can be transmitted to the electronic control device.

In the apparatus of the above embodiment, the amplitude ΔB of the magnetic flux detected by the Hall element 9b is set to 500 Gs or more, but the present invention is not limited to this, and a magnetic flux that can obtain a stable signal by amplification is obtained. Should be detected. For example, even when ΔB is set to 200 Gs or more, almost the same effect can be obtained by setting the amplification factor to 100 times.

FIG. 8 shows a diagram for explaining the effect of the apparatus of this embodiment. FIG. 7A shows the relationship between ΔB detected by the Hall element 9b of the apparatus of this embodiment and the gap between the Hall element 9b and the magnetic scale 10 (gap in FIG. 7). For reference, the description is given with reference to FIG.
ΔB detected by the Hall element 12 including the yoke 14 is shown as a comparative example. Further, FIG. 2B shows that the Hall element 9b of the above-mentioned embodiment and the Hall element 12 of the comparative example are
The magnetic flux detected when the gap (gap in FIG. 7) is 1 mm is shown.

As shown in each figure, the magnetic flux ΔB detected by the Hall element 9b of the apparatus of this embodiment is significantly higher than the magnetic flux detected by the Hall element 12 of the comparative example. Further, as is clear from FIG. 8A, in the case of ΔB ≧ 500 Gs (amplification factor 30 times), the apparatus of this embodiment can allow the gap up to 1.3 mm. Furthermore, ΔB ≧ 2
If it is 00 Gs (amplification factor 100 times), the gap is 2 mm.
It can be extended to

As described above, according to the vehicle height detecting apparatus of this embodiment, the vehicle height is accurately measured while the magnetic reading portion is built in the rod of the shock absorber, that is, the portion fixed to the vehicle body. It becomes possible to detect.
Therefore, in addition to the fact that there is no difference in external dimensions from the shock absorber in which the vehicle height detection device is not incorporated, since it is a structure in which wiring is provided in a portion fixed to the vehicle body,
Compared to conventional vehicle height detectors, it is extremely easy to install.

FIG. 9 is a block diagram of another embodiment of the vehicle height detecting device according to the present invention. In the figure, the same parts as those in FIGS. 1 and 2 are designated by the same reference numerals, and the description thereof will be omitted. Further, FIG. 1A shows a plan view and FIG. 1B shows a front sectional view.

In the figure, reference numerals 20a and 20b denote Hall elements having the same structure as the Hall element 9a of the above embodiment. These Hall elements 20a, 20b are provided in the longitudinal direction of the rod 4 at a pitch of 5/4 times the pitch of the magnetic scale 10, that is, a pitch of 5 mm.

Therefore, the output waveform of the Hall element 20a and the output waveform of the Hall element 20b are always output with a 1/4 pitch shift. Therefore, these outputs are “high”,
When binarized with "low", four states can be created by combining them.

Therefore, according to the vehicle height detecting apparatus of the present embodiment, even though the pitch of the magnetic scale 10 is 4 mm, the position can be detected at a quarter pitch, that is, at 1 mm intervals. Furthermore, it is detected whether the rod 4 is moving up or down with respect to the magnetic scale 10 by monitoring in what kind of pattern the above four states are paid out. Therefore, it is not necessary to separately provide a moving direction detection unit.

In addition, the apparatus of the present embodiment incorporates not only the sensor section in the rod 4 but also an amplifier circuit for amplifying the output signals of the Hall elements 20a and 20b. Therefore, the Hall elements 20a and 20b are electrically connected to the printed boards 23 and 24 via the printed board 21 and the flexible board 22 which are interposed between the Hall elements 20a and 20b.

The printed circuit boards 23 and 24 are mounted with the elements constituting the above-mentioned amplifier circuit.
A terminal 25 is joined to 3 for obtaining an electrical connection with an external circuit. The terminal 25 is connected to an electronic control unit mounted on the vehicle body via a wire (not shown) drawn from the upper end of the rod.

These functional parts are included in the circlips 26, 2 arranged above and below the printed circuit boards 23, 24.
7 and the resin portion 28 for fixing the printed boards 21, 23, 24, etc., and is stably held inside the rod 4.

As described above, according to the vehicle height detecting apparatus of the present embodiment, in addition to the Hall element for detecting the expansion and contraction of the shock absorber and the magnetic scale, an amplifying circuit can be built in the rod 4. Therefore, the signal transmitted from the shock absorber toward the vehicle body is an already amplified signal.

Therefore, according to the present embodiment device, in addition to the effect of the above embodiment device, while the detected signal is transmitted from the shock absorber to the on-vehicle electronic control device, it is generated from other equipment. It is less likely to be affected by noise such as electromagnetic waves, which improves the vehicle height detection accuracy.

[0062]

As described above, according to the present invention, since the rod fixed to the vehicle body has the directional magnetic sensing element and the magnetism generating means built therein, it is possible to compare with the conventional vehicle height detecting device. Therefore, the mountability on the vehicle body is significantly improved. Further, since it is only necessary to provide wiring to a portion fixed to the vehicle body, it is not necessary to prevent the wiring portion from sliding, and there is a feature that reliability is improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of a vehicle height detection device according to the present invention.

FIG. 2 is a configuration diagram of a shock absorber incorporating an embodiment of a vehicle height detection device according to the present invention.

FIG. 3 is a configuration diagram of a comparative example used for studying the configuration of the device of this embodiment.

FIG. 4 is a diagram showing a state of lines of magnetic force in a comparative example used for studying the configuration of the device of this embodiment.

FIG. 5 is a diagram showing a state of magnetic force lines in the apparatus of this embodiment.

FIG. 6 is a diagram showing a breakdown of a magnetic field detected by the device of this embodiment.

FIG. 7 is a diagram showing a state of magnetic force lines in the apparatus of this embodiment.

FIG. 8 is a diagram for explaining the effect of the device of this embodiment.

FIG. 9 is a configuration diagram of another embodiment of the vehicle height detection device according to the present invention.

[Explanation of symbols]

 1 Shock Absorber 2 Outer Cylinder 3 Inner Cylinder 4 Rod 5 Oil 9 Sensor 9a Magnet 9b, 20a, 20b Hall Element 10 Magnetic Scale 10a Magnetic Material 10b Non-Magnetic Material

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location G01R 33/06 H 8203-2G

Claims (1)

[Claims] 1. A magnetic scale provided on an inner wall of a cylinder, comprising a plurality of magnetic bodies and non-magnetic bodies arranged alternately, a magnetic generation means provided on a rod of the cylinder, and the magnetic generation means. And a directional magnetic sensitive element for detecting only a vertical component of the magnetic flux generated by the magnetic generation means toward the magnetic scale, the relative movement of the rod with respect to the cylinder relative to the vehicle height. A vehicle height detection device, which detects a movement to detect a vehicle height.