GB2353362A - Coil Transducer With Magnetic Field Compensating Means - Google Patents
Coil Transducer With Magnetic Field Compensating Means Download PDFInfo
- Publication number
- GB2353362A GB2353362A GB9919535A GB9919535A GB2353362A GB 2353362 A GB2353362 A GB 2353362A GB 9919535 A GB9919535 A GB 9919535A GB 9919535 A GB9919535 A GB 9919535A GB 2353362 A GB2353362 A GB 2353362A
- Authority
- GB
- United Kingdom
- Prior art keywords
- transducer
- coil
- transducer according
- magnetic field
- wound
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
- G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
- G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
- G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
- G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
- G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/01—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents
- B60R21/013—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over
- B60R21/0136—Electrical circuits for triggering passive safety arrangements, e.g. airbags, safety belt tighteners, in case of vehicle accidents or impending vehicle accidents including means for detecting collisions, impending collisions or roll-over responsive to actual contact with an obstacle, e.g. to vehicle deformation, bumper displacement or bumper velocity relative to the vehicle
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Geophysics And Detection Of Objects (AREA)
Abstract
A transducer 10 is disclosed which is suitable for a side intrusion detection system of a vehicle. The transducer 10 is a ferro-magnetic transducer and includes a flat wound spiral form coil 12 which is arranged in use to provide self-compensation against magnetic fields which might be induced in the transducer 10, such as could arise from eddy currents in a target member like a door skin 20.
Description
2353362 A Transducer This invention relates to transducers and in
particular to a transducer which is suitable for detecting the deformation or relative movement of at least a portion of an associated target member.
It is known to provide transducers for detecting the deformation or relative movement of associated target members. These transducers have been found to be suitable for use in detection systems such as those used for, but not limited to, side intrusion systems of vehicles. One general arrangement of this type can be seen with particular reference to Figure 1.
1 In Figure 1 an arrangement is provided for detecting the deformation of a door skin 3 of a vehicle (not shown further). The side intrusion detection arrangement comprises a plurality of coils 1 which are wound in a conventional bundle form with, in this case, a ferrite core 2. If the door skin 3 deforms in a side impact, it induces an inductance change in the coils 1 which is used to determine whether or not side airbags (not shown) should be deployed.
Because of their construction, these transducers 1, 2 have only a limited range, somewhat similar to the radius of the winding of their coils 1. They are therefore suitable only for measuring short distances, by which is meant that the transducer may have to be substantially in the immediate vicinity of the object 3.
It is a problem with such arrangements that eddy currents induced in the target object door skin 3 can induce a magnetic field in the transducer coils 1 such that their inductance, and therefore also their sensitivity, is altered.
The change in sensitivity can be represented in a simplified form by the ratio given below:
A5/ L LoAD in which AL is the change in inductance for the change in the distance AD to the door skin and L is the mean inductance in the change in distance AD.
For transducers of this type, one way to increase their range is to increase the diameter of their coils 1. The maximum possible coil diameter, however, may be constrained by the space available between the transducer 1, 2 and the sensed object 3. This means that, at the extreme of their range, such prior art transducers 1,2 exhibit only a low sensitivity.
The yeduced range and lower sensitivity of the prior art transducers 1, 2 is particularly disadvantageous when you are trying to detect side intrusion, as this should be detected as early as possible and is especially important in vehicles in which there is a large distance between the side impact transducer and the outer door skin or relevant door reinforcing structure.
It is an object of this invention to provide an improved transducer.
Accordingly, the invention provides a transducer suitable for detecting a deformation or relative movement of at least a portion of an associated target member, the transducer comprising a coil wound on a bobbin means, wherein said coil is wound in substantially a single plane as a substantially flat coil and said transducer is disposed in use such that the plane of winding of said coil is substantially parallel to the plane of said portion.
Said coil may be wound in a substantially spiral form and may be arranged to provide self-compensation of a magnetic field which may be induced therein from a source external to said transducer. Said self-compensation may be a function of the ratio of the spacing between substantially proximate windings of said coil and the diameter of said proximate windings themselves.
In use, said coil may be provided with a constant current.
Said bobbin means may comprise a ferro-magnetic core.
The invention also provides a detection system suitable for use as a side intrusion detection system of a vehicle, the system including a transducer according to the invention.
The invention will now be described by way of example only and with I reference to the remainder of the accompanying drawings, in which:
Figure 2 is a sectional side view of a transducer arrangement according to the invention; and Figure 3 is a plan view of the transducer of Figure 2.
Referring to Figures 2 and 3, a ferro-magnetic transducer 10 comprises a coil 12 which is wound as a substantially flat coil onto a bobbin means in the form of a ferro-magnetic core 14. The coil 12 is wound in a spiral form and has an inner coil end 16 and an outer coil end 18 which are connected to a side intrusion detection control means (not shown).
In use, the transducer 14 is disposed spaced apart from a portion of a door skin 20 in such a manner that the plane of winding of the coil 12 is substantially parallel to the plane of the portion of the door skin 20 which it uses as a target member.
In use, the coil 12 is supplied with a constant current by the control means and sets up a magnetic field which is disturbed if the door skin 20 closes the gap, as might occur rapidly in a side impact crash. The rapid approach of the door skin 20, will alter the magnetic field and cause an alteration in the inductance sensed by the control means so that it can make its decision on whether or not to deploy side airbags (not shown).
The coil 12 is arranged to provide localised self-compensation of its magnetic field against a magnetic field which might be induced therein as a result of eddy currents in the target member 20. The transducer inductivity, and therefore its sensitivity, is a function of the ratio between the spacing 60 of substantially proximat windings and the diameter 50 of the coil winding wire itself.
Winding Spacing 60 Winding Diameter 50 The compensation results in a damping of the magnetic field induced in the transducer 10 by eddy currents in the sensed object 20. This in turn leads to improved sensitivity and, the greater the ratio between the spacing 60 and the winding diameter 50, the higher will be the sensitivity.
The maximum sensitivity achievable can best be obtained by employing a particular number or range of windings, preferably after substantially all the other parameters have been fixed. Such values are best obtained by simulation or experimentation, as they will at least in part depend on the particular properties of the transducer materials, target materials and installation chosen.
A transducer according to the present invention provides better sensitivity at a particular range than a transducer including conventional bundle-form windings and, furthermore, our transducer delivers this advantage in a more compact package. This is especially advantageous in installations where space is limited.
The more compact nature of transducers made in accordance with our invention also means that less material is used to manufacture each unit and thus 5 costs can be saved.
It is not essential that the target member 20 is actually deformed. Relative movement between the target member 20 and the transducer 10 is all that is required to induce a signal change.
Claims (8)
1. A transducer suitable for detecting a deformation or relative movement of at least a portion of an associated target member, the transducer comprising a coil wound on a bobbin means, wherein said coil is wound in substantially a single plane as a substantially flat coil and said transducer is disposed in use such that the plane of winding of said coil is substantially parallel to the plane of said portion.
2. A transducer according to Claim 1, wherein said coil is wound in a substantially spiral form.
3. A transducer according to Claim I or Claim 2, wherein said coil is arranged to provide self-compensation of a magnetic field which may be induced therein from a source external to said transducer.
4. A transducer according to Claim 3, wherein said self-compensation is a function of the ratio of the spacing between substantially proximate windings of said coil and the diameter of said proximate windings themselves.
5. A transducer according to any preceding claim, wherein in use said coil is provided with a constant current.
6. A transducer according to any preceding claim, said bobbin means comprising a ferro-magnetic core.
7. A transducer substantially as described herein and with reference to Figures 2 and 3 of the accompanying drawings.
8. A detection system suitable for use as a side intrusion detection system of a vehicle, the system including a transducer according to any preceding claim.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9919535A GB2353362B (en) | 1999-08-19 | 1999-08-19 | A transducer |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9919535A GB2353362B (en) | 1999-08-19 | 1999-08-19 | A transducer |
Publications (3)
Publication Number | Publication Date |
---|---|
GB9919535D0 GB9919535D0 (en) | 1999-10-20 |
GB2353362A true GB2353362A (en) | 2001-02-21 |
GB2353362B GB2353362B (en) | 2003-10-08 |
Family
ID=10859371
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
GB9919535A Expired - Fee Related GB2353362B (en) | 1999-08-19 | 1999-08-19 | A transducer |
Country Status (1)
Country | Link |
---|---|
GB (1) | GB2353362B (en) |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2006005766A1 (en) * | 2004-07-14 | 2006-01-19 | Siemens Aktiengesellschaft | Device for detecting a collision |
WO2007103214A1 (en) * | 2006-03-07 | 2007-09-13 | Tk Holdings Inc. | Door mounted vehicle sensor |
US7772839B2 (en) | 2003-09-19 | 2010-08-10 | Tk Holdings, Inc. | Eddy current magnetic crash sensor |
US7839142B2 (en) | 2003-09-19 | 2010-11-23 | Tk Holdings, Inc. | Magnetic crash sensor |
US7839143B2 (en) | 2003-09-19 | 2010-11-23 | Tk Holdings Inc. | Eddy current magnetic crash sensor |
US7982590B2 (en) | 2007-10-22 | 2011-07-19 | Takata Coporation | Occupant restraint system |
US8180585B2 (en) | 1999-08-26 | 2012-05-15 | Tk Holdings, Inc. | Magnetic crash sensor |
Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1567600A (en) * | 1975-10-15 | 1980-05-21 | British Gas Corp | Lipe line inspection equipment |
GB2063485A (en) * | 1979-11-15 | 1981-06-03 | Bosch Gmbh Robert | Contactless Detection of the Distance of a Metal Surface from a Counter-surface |
US4706020A (en) * | 1983-12-12 | 1987-11-10 | General Electric Company | High frequency eddy current probe with planar, spiral-like coil on flexible substrate for detecting flaws in semi-conductive material |
US4951023A (en) * | 1984-07-14 | 1990-08-21 | Vacuumschmelze Gmbh | Electromagnetic drive apparatus having a flat coil |
EP0560396A2 (en) * | 1992-03-13 | 1993-09-15 | Kabushiki Kaisha Toshiba | Nuclear magnetic resonance imaging with improved image quality and operation efficiency |
EP0655628A2 (en) * | 1993-11-30 | 1995-05-31 | Fakulteta Za Elektrotehniko In Racunalnistvo | Integrated circuit with a magnetic field sensor |
-
1999
- 1999-08-19 GB GB9919535A patent/GB2353362B/en not_active Expired - Fee Related
Patent Citations (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB1567600A (en) * | 1975-10-15 | 1980-05-21 | British Gas Corp | Lipe line inspection equipment |
GB2063485A (en) * | 1979-11-15 | 1981-06-03 | Bosch Gmbh Robert | Contactless Detection of the Distance of a Metal Surface from a Counter-surface |
US4706020A (en) * | 1983-12-12 | 1987-11-10 | General Electric Company | High frequency eddy current probe with planar, spiral-like coil on flexible substrate for detecting flaws in semi-conductive material |
US4951023A (en) * | 1984-07-14 | 1990-08-21 | Vacuumschmelze Gmbh | Electromagnetic drive apparatus having a flat coil |
EP0560396A2 (en) * | 1992-03-13 | 1993-09-15 | Kabushiki Kaisha Toshiba | Nuclear magnetic resonance imaging with improved image quality and operation efficiency |
EP0655628A2 (en) * | 1993-11-30 | 1995-05-31 | Fakulteta Za Elektrotehniko In Racunalnistvo | Integrated circuit with a magnetic field sensor |
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US8180585B2 (en) | 1999-08-26 | 2012-05-15 | Tk Holdings, Inc. | Magnetic crash sensor |
US7772839B2 (en) | 2003-09-19 | 2010-08-10 | Tk Holdings, Inc. | Eddy current magnetic crash sensor |
US7839142B2 (en) | 2003-09-19 | 2010-11-23 | Tk Holdings, Inc. | Magnetic crash sensor |
US7839143B2 (en) | 2003-09-19 | 2010-11-23 | Tk Holdings Inc. | Eddy current magnetic crash sensor |
WO2006005766A1 (en) * | 2004-07-14 | 2006-01-19 | Siemens Aktiengesellschaft | Device for detecting a collision |
WO2007103214A1 (en) * | 2006-03-07 | 2007-09-13 | Tk Holdings Inc. | Door mounted vehicle sensor |
US7516981B2 (en) | 2006-03-07 | 2009-04-14 | Tk Holdings Inc. | Door mounted vehicle sensor |
US7982590B2 (en) | 2007-10-22 | 2011-07-19 | Takata Coporation | Occupant restraint system |
Also Published As
Publication number | Publication date |
---|---|
GB2353362B (en) | 2003-10-08 |
GB9919535D0 (en) | 1999-10-20 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20060819 |