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JPH10246620

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JPH10246620
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
magnetostrictive displacement detector. The present invention is applicable to the case of
detecting the displacement of the movable part.
[0002]
2. Description of the Related Art As shown in FIG. 6, as a magnetostrictive displacement detection
device, a substrate 100, a linear magnetostrictive material 200 held in a suspended state on the
substrate 100, and a magnetostrictive material facing the magnetostrictive material 200. It is
known that a ring-shaped permanent magnet 300 provided substantially coaxially with 200, a
pulse supply circuit 400 for supplying a current pulse to the magnetostrictive material 200, and
a receiving coil 500 are provided.
[0003]
The permanent magnet 300 is held by the movable portion 301, and moves relative to the base
100 along the extending direction of the magnetostrictive material 200, that is, along the
directions of arrows X1 and X2 as the movable portion 301 moves.
The detection principle of this magnetostrictive displacement detection device is as follows. That
is, when a current pulse is supplied to the magnetostrictive material 200 by the pulse supply
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circuit 400, a circumferential magnetic field is generated around the magnetostrictive material
200 based on the right-handed screw law. The supply time of the current pulse is the start time.
When this magnetic field is applied to the magnetic field of the permanent magnet 300, torsional
distortion occurs in the portion of the magnetostrictive material 200 facing the permanent
magnet 300 due to the Wiedemann effect.
[0004]
Then, an elastic wave based on the torsional strain of the magnetostrictive material 200 is
transmitted on the magnetostrictive material 200 at the speed of sound in the direction of the
arrow X1, that is, toward the receiving coil 500. When the elastic wave reaches the receiving coil
500, a magnetic field change based on the magnetostrictive inverse effect is detected by the
receiving coil 500 as an electromotive force. This detection time is the arrival time.
[0005]
Therefore, in the magnetostrictive displacement detection device described above, if the time
between the start time and the arrival time is measured, the distance Lo between the receiving
coil 500 and the permanent magnet 300 (see FIG. 6), ie, the extending direction of the
magnetostrictive material 200. The relative position of the permanent magnet 300 at is detected.
In this device, as can be understood from FIG. 6, the coil spring 600 and the damping member
700 are arranged in series. The coil spring 600 is for applying tension to the magnetostrictive
material 200 along the extending direction thereof. The damping member 700 is for damping the
excess elastic wave in the direction of the arrow X 2 and suppressing the reflection of the excess
elastic wave at the end of the magnetostrictive material 200. The tension applying function by
the coil spring 600 and the damping function by the damping member 700 ensure detection
accuracy in the magnetostrictive displacement detection device.
[0006]
In addition, as shown in FIG. 7, the magnetostrictive material 200, the receiving coil 500, and the
permanent magnet 300 are provided in Japanese Patent Laid-Open No. 7-306030, and the one
end 200c of the magnetostrictive material 200 is pulled by a coil spring 600. A magnetostrictive
displacement detection device of a type in which the outer peripheral surface of the other end
portion 200e of the magnetostrictive material 200 is crimped with a rubber damping member
700 while being fixed to the fixing portion 101 of 100 is disclosed.
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[0007]
By the way, in the magnetostrictive displacement detection apparatus according to the prior art
shown in FIG. 6 described above, both the damping member 700 and the coil spring 600 are
independently in series with the magnetostrictive material 200. It is provided.
Therefore, the length of the magnetostrictive displacement detection device tends to increase.
[0008]
Furthermore, since the damping member 700 and the coil spring 600 cause damping and
reflection of elastic waves, the region where the damping member 700 and the coil spring 600
are provided can easily constitute a dead region where displacement can not be detected.
Therefore, in the magnetostrictive displacement detection device in which both the damping
member 700 and the coil spring 600 are provided independently in series, the insensitive region
La (see FIG. 6) in which the displacement can not be detected tends to increase. Therefore, there
is a limit to the expansion of the detectable area Lc.
[0009]
Furthermore, also in the magnetostrictive displacement detection device shown in FIG. 7, both
the damping member 700 and the coil spring 600 are independently provided in series in the
magnetostrictive material 200. Therefore, the length of the magnetostrictive displacement
detection device tends to increase. Furthermore, there is a limit to the expansion of the detectable
area. The present invention has been made in view of the above situation, and each claim adopts
a method of arranging a coil spring and a damping member in series by adopting an elastic
member having both the function of the coil spring and the function of the damping member. An
object of the present invention is to provide a magnetostrictive displacement detection device
which can be abolished, thereby shortening the length of the magnetostrictive displacement
detection device, and further advantageous for expanding a detectable region capable of
detecting the relative position of a permanent magnet. .
[0010]
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The object of the present invention is to provide a magnetostrictive displacement detection
device that is advantageous for securing the damping function by the elastic member that
improves the degree of pressure bonding of the magnetostrictive material by the elastic member
and attenuates the excess elastic wave. Do. The fifth aspect of the present invention is
advantageous in setting the vicinity of one end of the accommodation tube as a detectable area
by directly coupling the one end of the magnetostrictive material to the one end of the
accommodation tube constituting the base without interposing a coil spring or the like.
Magnetostrictive displacement detection apparatus.
[0011]
A magnetostrictive displacement detection apparatus according to a first aspect of the present
invention comprises a base, a magnetostrictive material capable of generating an elastic wave
held by the base in an installation state extended in one direction, and a magnetostrictive
material. Tension applying means for applying tension along the extending direction of the
magnetostrictive member, a permanent magnet provided at a position facing the
magnetostrictive material and movable relative to the base along the extending direction of the
magnetostrictive material, Pulse generation means for supplying a current pulse flowing along
the extending direction of the magnet and a magnetic field generated by the current pulse and a
magnetic field generated by the permanent magnet, and the relative position of the permanent
magnet in the extending direction of the magnetostrictive material In the magnetostrictive
displacement detection apparatus, further comprising: receiving means for receiving an elastic
wave, and detecting the relative position of the permanent magnet upon reception, the tension
applying means is crimped to the magnetostrictive material and surplus transmitted along the
magnetostrictive material Can attenuate the elastic wave of A molecular material is used as a
base material, and is provided in a compressed state between the substrate and the
magnetostrictive material, tension is applied to the magnetostrictive material by tensioning the
magnetostrictive material by elastic restoring force accompanying compression, and a function to
attenuate excess elastic waves and It is characterized in that it is composed of an elastic member
having both of the magnetostrictive material tensioning functions.
[0012]
In the magnetostrictive displacement detection device according to the second aspect of the
present invention, in the first aspect, the magnetostrictive material has the engaging projection
projecting outward in the radial direction, and the elastic member is compressed in the extending
direction of the magnetostrictive material It is characterized in that it is interposed between the
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engaging projection and a part of the base in the state where it is held.
According to the magnetostrictive displacement detection device of the third aspect, in the first
aspect, a part of the base body is provided with the inclined surface, and the elastic member is
provided with the inclined surface pressing against the inclined surface. It is characterized in that
the degree of pressure bonding of the elastic member to the magnetostrictive material is
improved based on the pressure.
[0013]
According to the magnetostrictive displacement detection device of the fourth aspect, in the first
aspect, the elastic member has a cylindrical shape provided with a through hole into which the
magnetostrictive material is inserted, and the elastic member is in the extending direction of the
magnetostrictive material And the elastic deformation inward in the radial direction of the elastic
member accompanying the compression improves the degree of pressure bonding of the inner
peripheral surface of the through hole to the outer peripheral surface of the magnetostrictive
material. It is a thing.
[0014]
According to the magnetostrictive displacement detection device according to the fifth aspect, in
the first aspect, the base body has a long storage tube for storing the magnetostrictive material,
and one end of the magnetostrictive material is at one end of the storage tube. The elastic
member is disposed on the other end side of the magnetostrictive material and is disposed at a
position farther from the permanent magnet with respect to the permanent magnet in the
extending direction of the magnetostrictive material. It is said that.
[0015]
In the apparatus according to the first aspect of the present invention, current pulses are
supplied from the pulse supply means to the magnetostrictive material along the extending
direction thereof.
As in the prior art, when the magnetic field based on the current pulse acts on the magnetic field
of the magnetostrictive material, an elastic wave is generated in the portion of the
magnetostrictive material facing the permanent magnet.
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The elastic wave is transmitted along the magnetostrictive material and received by the receiving
means. Based on this, the relative position of the permanent magnet is detected.
[0016]
According to the device of the first aspect, the tension applying member is constituted by the
elastic member. The elastic member has both the function of applying tension to the
magnetostrictive material and the function of damping excess elastic waves transmitted along the
magnetostrictive material. Therefore, the problem which occurred in the prior art, that is, the
method of arranging the coil spring and the damping member in series in the extending direction
of the magnetostrictive material can be eliminated.
[0017]
According to the apparatus of the first aspect, as the elastic member, a polymer material member
having a polymer material as a base material can be adopted. Rubber or resin can be employed
as the polymer material. It may be non-foam or foam. Since the polymeric material has high
vibrational absorption capability, it can effectively attenuate the excess elastic wave transmitted
along the magnetostrictive material. According to the device of the second aspect, the elastic
member is provided with the engagement protrusion which protrudes outward in the radial
direction of the magnetostrictive material, and in the state in which the magnetostrictive material
is compressed in the extension direction Interspersed with some. Therefore, an elastic restoring
force based on the compression of the elastic member acts on the engagement protrusion of the
magnetostrictive material. Therefore, it is advantageous to apply tension to the magnetostrictive
material in the extending direction thereof.
[0018]
According to the device of the third aspect, a part of the base is provided with the inclined
surface, and the elastic member is also provided with the inclined surface. Therefore, based on
the pressure between the two inclined surfaces, an urging force that acts in the direction
perpendicular to the axis of the magnetostrictive material acts on the elastic member. The biasing
force improves the degree of pressure bonding of the elastic member to the magnetostrictive
material. According to the device of the fourth aspect, the elastic member has a cylindrical shape
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provided with a through hole into which the magnetostrictive material is inserted, and the elastic
member is compressed in the extending direction of the magnetostrictive material and
compressed. Accordingly, the degree of pressure bonding of the inner peripheral surface of the
through hole to the outer peripheral surface of the magnetostrictive material is improved by the
elastic deformation inward in the radial direction of the elastic member.
[0019]
According to the device of the fifth aspect, the elastic member is disposed at a position farther
from the permanent magnet than the receiving means in the extending direction of the
magnetostrictive material. Therefore, it is possible to attenuate the surplus elastic wave received
by the receiving means by the elastic member.
[0020]
A first embodiment of the present invention will be described below with reference to FIGS. The
present embodiment is applied to a height sensor mounted on a vehicle and detecting a height of
the vehicle. (Structure of the Embodiment) As can be understood from FIG. 1, the base body 1 is
an elongated storage tube 10 formed of nonmagnetic material (for example, brass, aluminum
alloy) having a storage chamber 10a, and a storage tube The circuit board 14 is connected to the
other end 10 e of the body 10 via the ground electrode 12, and the resin holder 18 is fixed to the
circuit board 14 via the leg 23.
[0021]
The housing tube 10 is fixed to a fixing portion 65 such as a vehicle body. The ground electrode
12 is electrically connected to the storage tube 10, and connects the storage tube 10 to the GND
terminal. The holder 18 is disposed on the side of the other end 10 e of the storage tube 10, and
is disposed substantially coaxially with the storage tube 10 and the magnetostrictive material 5.
[0022]
As can be understood from FIG. 2, the housing tube 10 extends in the directions of the arrows X1
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and X2, and is provided with a closing wall 10f at one end 10c in the longitudinal direction. The
closed end 10 f is a reflection end that reflects the elastic wave that has traveled in the arrow X 2
direction. The magnetostrictive material 5 linearly extends in the storage chamber 10a. The
magnetostrictive material 5 can be formed of, for example, a Ni-Fe-based alloy. One end 5 c of
the magnetostrictive material 5 is directly coupled to the closing wall 10 f of the housing tube 10
without a coil spring or the like. Soldering, screwing or the like can be employed as the coupling
means.
[0023]
As can be understood from FIG. 2, a ring-shaped permanent magnet 6 is provided so as to
surround the magnetostrictive material 5 substantially coaxially. An inner circumferential surface
6i of the permanent magnet 6 is opposed to the magnetostrictive material 5 via the housing tube
10. The permanent magnet 6 is held by a movable movable portion 60 such as a suspension, and
moves relative to the magnetostrictive material 5 in the directions of arrows X1 and X2 as the
movable portion 60 moves. The axial end faces 6a and 6c of the permanent magnet 6 are used as
magnetic poles (N pole, S pole).
[0024]
The other end 5 e of the magnetostrictive material 5 is electrically connected to a pulse supply
circuit 70 as a pulse supply unit through a feed signal line 71 and an electrode 71 k. The
receiving coil 4 as the receiving means is located on the side of the other end 5 e of the
magnetostrictive material 5 and is wound around and held by the holder 18. As shown in FIG. 2,
the distance between the receiving coil 4 and the closed end wall 10 f is indicated by L.
[0025]
A waveform shaping circuit 75 is electrically connected to the reception coil 4 via the reception
signal line 73. The pulse supply circuit 70 and the waveform shaping circuit 75 are connected to
the signal processing / time measurement circuit 77 via the signal lines 70r and 75r,
respectively. The signal processing / time measurement circuit 77 comprises a crystal oscillator.
Assuming that the frequency of the crystal oscillator is 50 MHz, for example, one clock is 1 /
(50.times.10@6) = 0.02 microseconds. Therefore, it is possible to measure in microseconds by
using the rise and fall of the clock. The pulse supply circuit 70, the waveform shaping circuit 75,
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and the signal processing / time measurement circuit 77 are mounted on the circuit board 14.
[0026]
As can be understood from FIG. 1, the holder 18 has a first wall 19, a second wall 20 facing the
first wall 19 at a predetermined distance, and a coil winding connecting the first wall 19 and the
second wall 20. And a through hole 22 extending in the length direction of the magnetostrictive
material 5. The inner diameter of the insertion hole 22 is set larger than the outer diameter of
the magnetostrictive material 5. Therefore, as can be understood from FIG. 1, when the
magnetostrictive material 5 is inserted into the insertion hole 22 of the holder 18, a ring-shaped
minute gap is formed between the inner peripheral surface of the insertion hole 22 and the outer
peripheral surface of the magnetostrictive material 5. 25 are formed.
[0027]
The first wall 19 of the holder 18 is formed with a fitting portion 26 for fittingly holding the
other end 10 e of the storage tube 10. The second wall 20 of the holder 18 is formed with a
substantially conical inclined surface 20 x having an imaginary apex on the approximate center
line of the magnetostrictive material 5. At the other end 5 e of the magnetostrictive material 5, an
engagement protrusion 52 protruding outward in the radial direction of the magnetostrictive
material 5 is fixed. The engagement protrusion 52 has a disk shape. As a fixing means of the
engaging projection 52, caulking, soldering, press-fitting or the like can be adopted. The
engagement protrusion 52 may be metal or resin.
[0028]
As can be understood from FIG. 1, an elastic member 8 functioning as a tension applying means
is provided on the side of the other end 5 e of the magnetostrictive material 5. The elastic
member 8 is made of rubber having a predetermined thickness, functions as a polymer material
member, and has a cylindrical shape having a through hole 82 penetrating in the extending
direction of the magnetostrictive material 5. An inclined surface 8x is formed at one end of the
elastic member 8 in the longitudinal direction. The inclined surface 8 x of the elastic member 8
has a substantially conical shape with an imaginary top on the approximate center line of the
magnetostrictive material 5. Therefore, the inclined surface 8x has an inclination angle
corresponding to the inclined surface 20x.
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[0029]
As can be understood from FIG. 1, the other end 5 e of the magnetostrictive material 5 is inserted
into the insertion hole 22 of the holder 18 with a minute gap 25 therebetween, and is inserted
into the through hole 82 of the elastic member 8. . In the present embodiment, the inner
peripheral surface of the through hole 82 of the elastic member 8 is crimped to the outer
peripheral surface of the magnetostrictive material 5 so that the excess elastic wave transmitted
along the magnetostrictive material 5 can be effectively attenuated.
[0030]
In the present embodiment, the elastic member 8 is disposed at a position farther from the
permanent magnet 6 than the receiving coil 4 in the extending direction of the magnetostrictive
material 5, that is, the directions of the arrows X1 and X2. Accordingly, the elastic wave traveling
on the magnetostrictive material 5 in the direction of the arrow X1 is not attenuated by the
elastic member 8 before being received by the receiving coil 4. That is, the excess elastic wave
after being received by the receiving coil 4 is attenuated by the elastic member 8. Therefore,
detection accuracy is ensured.
[0031]
In the present embodiment, as can be understood from FIG. 1, the elastic member 8 is interposed
between the engagement projection 52 and the second wall 20 of the holder 18. As a result, the
elastic member 8 is compressed in the axial direction of the elastic member 8, in other words, in
the extending direction of the magnetostrictive material 5 (the directions of arrows X 1 and X 2).
In the present embodiment, the holder 18 abuts on the other end 10 e of the storage tube 10,
and the position of the holder 18 is defined. Therefore, based on the compressive deformation of
the elastic member 8, an elastic restoring force in the direction of the arrow X 1, which the
elastic member 8 tends to extend in the axial direction, acts on the engagement protrusion 52.
Therefore, the elastic member 8 pulls the other end 5e of the magnetostrictive material 5 in the
arrow X1 direction. As a result, tension is applied to the magnetostrictive material 5. Therefore,
the degree of tension of the magnetostrictive material 5 is secured, and detection using the
magnetostrictive material 5 is performed well.
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[0032]
In the present embodiment, as described above, since the elastic member 8 is compressed in the
axial direction, the inclined surface 8x of the elastic member 8 is pressed against the inclined
surface 20x of the second wall 20 of the holder 18. Therefore, an urging force F directed radially
inward is generated in the rubber portion in the vicinity of the inclined surface 8x of the elastic
member 8 by the pressing of the inclined surfaces 20x and 8x. Therefore, the inner peripheral
surface of the through hole 82 of the elastic member 8 is effectively pressure-bonded to the
outer peripheral surface of the magnetostrictive material 5. Thus, the force with which the elastic
member 8 grips the magnetostrictive material 5 is increased. Accordingly, the degree of contact
between the elastic member 8 and the magnetostrictive member 5 is improved, and the function
of damping the excess elastic wave by the elastic member 8 is secured.
[0033]
The operation of the magnetostrictive displacement detection apparatus according to the present
embodiment will be described with reference to FIG. 3 and the like which show timings of signal
waveforms. FIG. 3A shows a signal waveform in the pulse supply circuit 70. FIG. FIG. 3B shows
the signal waveform received by the receiving coil 4. FIG. 3C shows a signal waveform obtained
by shaping the signal waveform received by the receiving coil 4 into a rectangular wave by the
waveform shaping circuit 75. FIG. 3D shows a waveform obtained by performing signal
processing on the rectangular wave signal waveform-shaped by the waveform shaping circuit 75
by the signal processing / time measurement circuit 77. FIG.
[0034]
In the present embodiment, the current pulse Ic shown in FIG. 3A is supplied from the pulse
supply circuit 70 to the other end 5 e of the magnetostrictive material 5. The current pulse Ic
flows from the other end 5e to the one end 5c of the magnetostrictive material 5 along the
magnetostrictive material 5 in the direction of the arrow X2. A magnetic field change based on
the current pulse Ic is detected as an excitation signal C1 (see FIG. 3B) by the receiving coil 4
when passing through the receiving coil 4. The supply time of the current pulse Ic is taken as the
start time.
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[0035]
As in the case of the conventional magnetostrictive displacement detection device, when the
magnetic field based on the current pulse Ic acts on the magnetic field of the permanent magnet
6, torsional distortion occurs in the portion of the magnetostrictive material 5 facing the
permanent magnet 6. As a result, an elastic wave based on the torsional strain travels on the
magnetostrictive material 5 at the speed of sound in the direction of the arrow X1, that is, toward
the receiving coil 4. When the elastic wave reaches the receiving coil 4, a magnetic field change
based on the magnetostrictive inverse effect is detected by the receiving coil 4 as a direct wave
signal C2 (see FIG. 3B). This detection time is the arrival time. When the elastic wave forming the
direct wave signal C 2 reaches the elastic member 8, the elastic wave is attenuated by the
internal friction of the elastic member 8 or the like.
[0036]
As described above, since the surplus elastic wave received by the receiving coil 4 is attenuated
by the elastic member 8, it is advantageous for shortening the time interval until the next current
pulse supply. In the present embodiment, the time To (see FIG. 3C) between the start time and
the arrival time described above is measured by the signal processing / time measurement circuit
77. Here, when the distance between the receiving coil 4 and the permanent magnet 6 is Lo (see
FIG. 2) and the velocity (sound velocity) of the elastic wave is V, Lo = V × To is basically
established.
[0037]
Since V can be considered to be substantially constant, if time To is measured, the distance Lo
between the receiving coil 4 and the permanent magnet 6 is detected. As a result, the relative
position of the permanent magnet 6 in the extending direction of the magnetostrictive material 5
is detected. According to this embodiment, the distance L (see FIG. 2) between the receiving coil
4 and the closing wall 10f is a detectable area. In the present embodiment, an elastic wave
generated at a portion of the magnetostrictive material 5 facing the permanent magnet 6 in FIG.
2 also travels on the magnetostrictive material 5 in the direction of the arrow X2. And the elastic
wave which advanced in the arrow X 2 direction is reflected by the closed end 10 f which
functions as a reflective end, and goes to the arrow X 1 direction. When this elastic wave reaches
the receiving coil 4, it is detected as a reflected wave signal C3 (see FIG. 3B) by the receiving coil
4 as described above.
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[0038]
In the present embodiment, the reflected wave signal C3 is not particularly used. When the
elastic wave forming the reflected wave signal C3 reaches the elastic member 8, it is attenuated
by internal friction of the elastic member 8 or the like. Thus, since the excess elastic wave is
attenuated by the elastic member 8, it is advantageous for shortening the time interval until the
next current pulse supply. FIG. 4 shows the flow of the operation procedure described above. In
step S2, a current pulse Ic is supplied. In step S4, measurement of time is started. At step S6, the
signal C2 is detected. In step S8, the measurement of the time To ends. In step S10, the distance
Lo is converted from the measured time To. Thereby, the relative position of the permanent
magnet 6 is determined.
[0039]
(Effects of the Embodiment) As described above, according to this embodiment, the elastic
member 8 functioning as a tension applying member has a function of pulling the other end 5 e
of the magnetostrictive material 5 to apply tension to the magnetostrictive material 5 It has both
the function of attenuating the excess elastic wave transmitted along the magnetostrictive
material 5. Therefore, it is possible to eliminate the coil spring for tension application which is
essential in the prior art shown in FIGS. 6 and 7 in order to apply tension to the magnetostrictive
material 5. Therefore, the method of arranging both the damping member for signal attenuation
and the coil spring for tension application in series along the extending direction of the
magnetostrictive material 5 can be eliminated. As a result, the length of the magnetostrictive
displacement detection device is suppressed.
[0040]
Furthermore, since it is possible to abolish the method in which both the damping member and
the coil spring which easily constitute the insensitive area are arranged in series along the
extending direction of the magnetostrictive material 5, it is advantageous for expanding the
detection area in the magnetostrictive displacement detection device. . Further, according to the
present embodiment, as shown in FIG. 2, the one end 5c of the magnetostrictive material 5 is
directly coupled to the closing wall 10f of the one end 10c of the housing tube 10 without a coil
spring or a damping member. . Accordingly, it is advantageous to set the vicinity of one end 10 c
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of the storage tube 10 as the detectable region.
[0041]
Further, according to the present embodiment, the magnetostrictive member 5 is provided with
the engaging projection 52 projecting radially outward, and the elastic member 8 is provided
between the holder 18 which is a part of the base 1 and the engaging projection 52. Being
interposed in the compressed state, it is advantageous for applying tension to the
magnetostrictive material 5. Accordingly, the degree of tension of the magnetostrictive material 5
is increased, and the detection accuracy is secured. According to the present embodiment, as
described above, since the elastic member 8 is interposed between the engaging projection 52 of
the magnetostrictive material 5 and the holder 18, the elastic member 8 can be understood from
FIG. Although the elastic restoring force acts on the holder 18, it does not act directly on the
circuit board 14, and the protection of the circuit board 14 can be secured.
[0042]
Further, according to the present embodiment, since the elastic member 8 is compressed in the
axial direction, the inclined surface 8x of the elastic member 8 is strongly pressed against the
inclined surface 20x of the second wall 20 of the holder 18. Therefore, an urging force F directed
radially inward is generated in the rubber portion in the vicinity of the inclined surface 8x of the
elastic member 8 by the pressing of the inclined surfaces 8x and 20x. Therefore, the inner
peripheral surface of the through hole 82 of the elastic member 8 is effectively pressure-bonded
to the outer peripheral surface of the magnetostrictive material 5. Therefore, the force with
which the elastic member 8 grips the outer peripheral surface of the magnetostrictive material 5
is increased. Therefore, the function of damping the excess elastic wave by the elastic member 8
is effectively ensured.
[0043]
In addition, according to the present embodiment, as described above, the elastic member 8
made of rubber as the base material is the elastic member 8 in the extending direction of the
magnetostrictive material 5 between the engagement projection 52 and the holder 18. It is
compressed in the axial direction. In general, the rubber has a relatively high Poisson's ratio, and
the elastic member 8 bulges radially inward and outward in accordance with the compression
04-05-2019
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volume in the axial direction of the elastic member 8. Therefore, the entire inner peripheral
surface of the through hole 82 of the elastic member 8 can be easily crimped to the outer
peripheral surface of the magnetostrictive material 5 by the inward bulging portion of the elastic
member 8. Therefore, securing of the damping function by the elastic member 8 can be expected.
[0044]
Furthermore, in the present embodiment, the inclined surface 20 x of the holder 18 has a conical
shape in which the imaginary top is located on the axis of the magnetostrictive material 5. The
inclined surface 8x of the elastic member 8 also has a conical shape having a similar inclination
angle. Therefore, the "centering effect" is generated by the pressing of the inclined surfaces 20x
and 8x. Thus, the position of the central axis of the elastic member 8 in the radial direction is
defined. Accordingly, it is advantageous to arrange the central axis of the other end 5 e of the
magnetostrictive material 5 held by the elastic member 8 at the center of the insertion hole 22 of
the holder 18 in the radial direction. Therefore, the width of the minute gap 25 can be properly
secured. That is, it is advantageous for suppressing the contact of the outer peripheral surface of
the magnetostrictive material 5 with the inner peripheral surface of the insertion hole 22 of the
holder 18. Therefore, it is advantageous for securing detection accuracy.
[0045]
Further, in the present embodiment, although the elastic member 8 is disposed in the vicinity of
the receiving coil 4, the elastic member 8 is made of rubber as a base material, so the magnetic
permeability is low. Do not give Second Embodiment FIG. 5 shows a second embodiment. The
second embodiment basically has the same configuration as the first embodiment, and basically
exhibits the same function and effect. Therefore, the same code | symbol is attached | subjected
to the site | part which plays the same function.
[0046]
In this example, the regulation cylinder 28 is integrally extended from the holder 18. The
restricting cylinder 28 covers the outer peripheral surface 8 t of the elastic member 8
substantially coaxially. As described above, the elastic member 8 is compressed in its axial
direction. Therefore, depending on the compression volume in the axial direction of the elastic
04-05-2019
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member 8, the elastic member 8 bulges radially outward and inward.
[0047]
In this respect, in the present embodiment, since the radially outward expansion of the elastic
member 8 is restricted by the restriction cylinder 28, it is advantageous to further expand the
elastic member 8 radially inward. Accordingly, the degree to which the inner peripheral surface
of the through hole 82 of the elastic member 8 is effectively pressure-bonded to the outer
peripheral surface of the other end 5 e of the magnetostrictive material 5 is improved. Therefore,
the grip of the magnetostrictive member 5 by the elastic member 8 is improved, and securing of
the damping function by the elastic member 8 can be expected.
[0048]
Furthermore, in the second embodiment, as can be understood from FIG. 5, the other end 5 e of
the magnetostrictive material 5 is bent into a substantially L shape, and the other end 5 e of the
magnetostrictive material 5 and the engagement projection 52 Thus, the engagement of the
engaging protrusion 52 is improved, and the retaining property of the engaging projection 52 is
improved. (Other Example) In the above-described embodiment, the housing tube 10 is fixed to a
fixed portion such as a vehicle body, and the permanent magnet 6 is held by the movable portion
60. With the movement of the movable portion 60, the permanent magnet 6 is fixed. Is a method
of moving along the length direction of the storage tube 10.
[0049]
However, the present invention is not limited thereto, and the permanent magnet 6 may be fixed,
the storage tube 10 may be held by the movable portion 60, and the storage tube 10 may be
moved relative to the permanent magnet 6 with the movement of the movable portion 60. .
[0050]
According to the apparatus of the present invention, the elastic member as the tension applying
member has a function to apply tension to the magnetostrictive material and a function to
attenuate an excess elastic wave transmitted along the magnetostrictive material. And both.
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Therefore, the coil spring for applying tension to the magnetostrictive material employed in the
prior art shown in FIGS. 6 and 7 can be eliminated. Therefore, the method of arranging the
damping member and the coil spring in series in the extending direction of the magnetostrictive
material can be eliminated. Therefore, it is advantageous to suppress an increase in the length of
the magnetostrictive displacement detection device.
[0051]
Furthermore, as described above, since the method of arranging in series the coil spring and the
damping member that easily configure the insensitive area can be eliminated, it is advantageous
to reduce or eliminate the undetectable insensitive area that has conventionally occurred. It is
advantageous for the expansion of the possible area. According to the device of the second
aspect, since the elastic member is interposed between the engaging protrusion and a part of the
base in a state of being compressed in the extending direction of the magnetostrictive material,
the tension is applied to the magnetostrictive material It is advantageous to give Therefore, the
degree of tension of the magnetostrictive material can be secured, which is advantageous for
securing detection accuracy.
[0052]
According to the device of the third aspect, the degree of pressure bonding of the elastic member
to the magnetostrictive material is improved based on the pressure between the inclined
surfaces. Therefore, it is advantageous to improve the damping function by the elastic member.
According to the device of the fourth aspect, the degree of the pressure bonding of the inner
peripheral surface of the through hole with the outer peripheral surface of the magnetostrictive
material is improved by the elastic deformation of the elastic member accompanying the
compression. Therefore, it is advantageous to improve the damping function by the elastic
member.
[0053]
According to the device of the fifth aspect, the one end of the magnetostrictive material is
directly coupled to the one end of the storage tube without interposing the coil spring or the
damping member. Therefore, it is advantageous to set the vicinity of one end of the storage tube
04-05-2019
17
as a detectable area. Further, according to the device of the fifth aspect, the elastic member is
disposed at a position farther from the permanent magnet than the receiving means in the
extending direction of the magnetostrictive material. Therefore, the excess elastic wave received
by the receiving means can be attenuated by the elastic member. That is, it is possible to prevent
the elastic member from damping the elastic wave before being received by the receiving means.
Therefore, both the detection accuracy and the attenuation of the excess elastic wave are
effectively performed.
[0054]
Brief description of the drawings
[0055]
1 is a cross-sectional view of the main part according to the first embodiment.
[0056]
2 is a block diagram of the whole according to the first embodiment.
[0057]
3 is an explanatory view showing the timing of the signal waveform according to the first
embodiment.
[0058]
4 is an explanatory view showing an operation procedure according to the first embodiment.
[0059]
5 is a cross-sectional view of the main part according to the second embodiment.
[0060]
6 is a block diagram of the whole according to the prior art.
[0061]
It is a block diagram of the whole which concerns on the prior art of FIG. 7 another.
04-05-2019
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[0062]
Explanation of sign
[0063]
In the figure, 1 is a base, 10 is a housing tube, 18 is a holder, 4 is a receiving coil (receiving
means), 5 is a magnetostrictive material, 52 is an engaging protrusion, 6 is a permanent magnet,
70 is a pulse supply circuit (pulse Supply means 8) is an elastic member, 8x is an inclined
surface, and 20x is an inclined surface.
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