WO2016157773A1

WO2016157773A1 - Coil unit

Info

Publication number: WO2016157773A1
Application number: PCT/JP2016/001470
Authority: WO
Inventors: 朋宏久野
Original assignee: 株式会社デンソー
Priority date: 2015-03-27
Filing date: 2016-03-15
Publication date: 2016-10-06
Also published as: JP2016186973A

Abstract

This coil unit is provided with a coil, and a second conductive member, which is disposed between the coil and a first conductive member disposed close to the coil, said first conductive member having conducting properties, and which suppresses a coil impedance change due to the first conductive member, said second conductive member having conducting properties. Consequently, the coil impedance change that occurs when the coil is brought close to a member that increases the impedance can be suppressed, thereby making it possible to reduce the impedance even if a distance between the first conductive member, i.e., the coil installation surface, and the coil is not ensured, and reducing the coil installation height.

Description

Coil unit

Cross-reference of related applications

This application is based on Japanese Patent Application No. 2015-0666026 filed on Mar. 27, 2015, the disclosure of which is incorporated herein by reference.

The present disclosure relates to a coil unit including a coil.

Electronic key systems that transmit and receive radio waves between a portable device owned by the user and an in-vehicle device mounted on the vehicle, and lock / unlock the door and start the engine when the codes match, have become widespread. ing.

In the above-described system, an LF (long wave) band radio wave is used to transmit a radio signal from the in-vehicle device to the portable device. If a metal exists in the vicinity of an antenna for transmitting a radio signal, the resonance frequency changes. In view of this, an antenna device has been devised in which the coil bobbin can be fixed at different positions of the case in the axial direction of the core inserted into the coil bobbin and the resonance frequency can be easily adjusted (see Patent Document 1).

JP 2006-229759 A

When metal is present near the coiled antenna, the resonance frequency changes as described above, and the coil impedance also increases. A change in the resonance frequency can be prevented by adjusting the inductance value in advance according to the mounting state of the antenna. As for the increase in impedance, there are a method of increasing the voltage of the driver for driving the antenna or a method of securing a distance between the antenna and the surrounding metal.

However, in order to increase the driver voltage, the booster circuit may become large or complicated, or the current consumption may increase. In addition, there are cases where the voltage cannot be increased because an appropriate driver cannot be used due to the limitation of the capacity of the housing that houses the antenna. If the voltage is insufficient, sufficient antenna current cannot be secured, the output electric field strength decreases, the communication distance becomes short, and communication cannot be performed.

In order to secure the distance between the antenna and the surrounding metal, the antenna housing may be enlarged or a spacer may be provided between the antenna and the mounting surface (peripheral metal), but the antenna may be enlarged.

This disclosure is intended to provide a coil unit that can suppress an increase in coil impedance even when the coil is disposed close to a conductive member.

According to the first aspect of the present disclosure, the coil unit is disposed between the coil, the coil, and the first conductive member having conductivity, which is disposed in the vicinity of the coil, and the coil is formed by the first conductive member. And a second conductive member having conductivity that suppresses a change in impedance.

According to the second aspect of the present disclosure, the electronic key system collates the portable key by wireless communication between the portable key, the in-vehicle device mounted on the vehicle, and the portable key and the in-vehicle device. ECU which performs predetermined control based on. The in-vehicle device includes an antenna of a verification request transmission unit that transmits a verification request signal to the portable key. The portable key includes an antenna of a verification request receiving unit that receives a verification request signal. Both the antenna of the verification request transmitting unit and the antenna of the verification request receiving unit include the coil unit.

With the above configuration, it is possible to suppress a change (increase) in impedance when the coil (inductor) is brought close to a member (first conductive member) that increases impedance. Thereby, even if it does not ensure the distance between the member (1st electroconductive member) of the attachment surface of a coil, and a coil, impedance reduction is attained and the attachment height of a coil can be made low.

1 is a diagram illustrating an electronic key system according to an embodiment of the present disclosure. FIG. The partial cross section figure which shows the antenna (coil unit) by one Example. III-III sectional view of FIG. 1 is a partial cross-sectional view showing an antenna according to one embodiment. 1 is a partial cross-sectional view showing an antenna according to one embodiment. 1 is a partial cross-sectional view showing an antenna according to one embodiment. 1 is a partial cross-sectional view showing an antenna according to one embodiment. 1 is a partial cross-sectional view showing an antenna according to one embodiment. The figure which shows the equivalent circuit of the antenna of the comparative example of this indication. The figure which shows the relationship between the distance of a coil and the 1st electrically-conductive member, and the impedance of an antenna by one Example of this indication. The figure which shows the equivalent circuit of the antenna of this indication.

An embodiment in which the coil unit of the present disclosure is applied to an electronic key system will be described. As shown in FIG. 1, the electronic key system 100 includes an ECU 4 (on-vehicle device) mounted on the vehicle 1, an outdoor LF transmission unit 41 (on-vehicle device, verification request transmission unit), an indoor LF transmission unit 43 ( An in-vehicle device, a verification request transmission unit), an RF reception unit 45, a door unit 5, a start switch 6, and a portable key 3 possessed by the user.

The ECU 4, the door unit 5, and the start switch 6 are connected by a communication line 7 such as a LAN and can communicate with each other.

ECU4 is comprised as a computer containing well-known CPU and a peripheral circuit. The ECU 4 includes a memory 40 that is a non-volatile storage medium for storing various information necessary for the operation of the electronic key system 100 such as a master code for collation of the portable key 3.

The outdoor LF transmitter 41 is, for example, inside the pillar of the vehicle body, inside the side sill that is a frame member arranged on the lower side of the door, inside the side step attached to the side sill, rear bumper, or inside the door unit 5. Provided. The indoor LF transmitter 43 is provided in the vehicle 1. The outdoor LF transmitter 41 and the indoor LF transmitter 43 use the LF (long wave) band or the VLF (very long wave) radio wave, for example, in the range of about 1 to 2 m from the

antennas

42 and 44. Send.

The RF receiver 45 is provided, for example, inside the center console in the passenger compartment. The RF receiver 45 receives a response signal from the portable key 3 or an RKE (remote keyless entry) command signal transmitted from the outside of the vehicle or from the vehicle interior using radio waves in the RF (high frequency) band by the antenna 46. By using radio waves in the RF band, a signal from the portable key 3 can be received even when the user is away from the vehicle 1 (for example, 30 to 100 m).

The door unit 5 includes a lock device 50, a touch sensor 51, and a lock button 52. The door unit 5 is a generic term for each door unit of a plurality of doors of the vehicle 1. The plurality of doors include a driver seat side door, a passenger seat side door, a rear seat right door, a rear seat left door, and the like.

The lock device 50 includes an actuator such as a motor and its drive circuit, and switches and controls the lock state and the unlock state based on a control command from the ECU 4. The touch sensor 51 is provided on the door handle and detects that the user has gripped the door handle. The lock button 52 is provided near the door handle and detects a user's door lock operation.

The start switch 6 is a switch for bringing the prime mover (engine or motor) of the vehicle 1 into a start state or a start permission state.

The portable key 3 includes a control unit 32, an LF reception unit 30 (collation request reception unit), an RF transmission unit 31, a memory 33 that is a nonvolatile storage medium, and an operation unit 34 connected to the control unit 32. The control unit 32 is configured as a known computer and controls the operation of the entire portable key 3. The memory 33 stores an ID code for identifying the portable key 3 together with data necessary for the operation of the portable key 3.

The LF receiver 30 receives a verification request signal from the vehicle 1 via the antenna 30a. When the LF receiver 30 receives the signal, the controller 32 causes the RF transmitter 31 to transmit a response signal including an ID code from the antenna 31a.

The operation unit 34 is a push switch group for using the RKE function. When the user operates the operation unit 34, for example, an RKE command signal for locking / unlocking or opening / closing a door or trunk is transmitted from the RF transmission unit 31.

With the configuration as described above, when the touch sensor 51 detects an operation for unlocking the door by the user to hold the door handle, the electronic key system 100 requests a collation request from the outdoor LF transmitter 41 to the portable key 3. A signal is transmitted a predetermined number of times. When the portable key 3 receives the verification request signal, it returns a response signal from the RF transmitter 31. The ECU 4 collates the ID code and the master code included in the received response signal, and if the collation is successful, outputs a control command to the lock device 50 so that the door is unlocked.

Further, when the user gets on and operates the start switch 6, a signal for requesting collation is transmitted from the indoor LF transmitter 43 to the portable key 3 a predetermined number of times. When the portable key 3 receives the verification request signal, it returns a response signal. The ECU 4 performs collation in the same manner as described above. If the collation is successful, the control command for setting the prime mover in the start state or the start permission state is transmitted to the prime mover ECU that performs rotation control of the prime mover of the vehicle 1 via the communication line 7. Is output.

The coil unit of the present disclosure is used for the

antennas

42, 44, and 30a. The outdoor LF transmission unit 41, the indoor LF transmission unit 43, and the LF reception unit 30 may be a communication device using a long wave band. With this configuration, the configuration of the present disclosure can be applied to an antenna for long wave band communication that requires longer communication distance and reduced current consumption.

Moreover, the said structure contains the portable key 3 which a user possesses, and the vehicle-mounted apparatus (ECU4, outdoor LF transmission part 41, indoor LF transmission part 43) mounted in the vehicle, between a portable key and vehicle-mounted apparatus. The portable key is verified by wireless communication. In the electronic key system that performs predetermined control based on the comparison result, the coil 72 includes a verification request transmission unit (outdoor LF transmission unit 41, indoor LF transmission unit) that transmits a verification request signal to the portable key of the in-vehicle device. 43) and antennas 30a of the collation request receiving unit (LF receiving unit 30) that receives the collation request signal of the portable key. With this configuration, in an electronic key system for vehicles in which restrictions on current consumption (particularly dark current) are severe, an increase in current consumption can be suppressed, and an output electric field strength and a communication distance necessary for communication can be secured.

Hereinafter, the coil unit will be described using the antenna 42 as an example. The

antennas

44 and 30a have the same configuration as the antenna 42. 2 is a side view of the inside of the antenna 42, and FIG. 3 is a cross-sectional view taken along the line III-III of FIG. A terminal or lead wire for connecting the antenna 42 to the outdoor LF transmitter 41 is not shown.

The antenna 42 is made of a bobbin 71, a coil 72 wound around the bobbin 71, ferrite, amorphous, or the like, and a core 73 inserted into the bobbin 71 is housed in a substantially rectangular casing 74 made of, for example, resin. . A configuration without the bobbin 71 and the core 73 is also possible. Both ends of the bobbin 71 are in contact with the inner wall surface of the lower part of the casing 74, thereby supporting the coil 72. Both end portions of the bobbin 71 may be fixed to the inner wall surface of the lower portion of the housing 74. Further, the bobbin 71 may be in contact with the inner wall surface at the top of the housing 74.

The housing 74 is attached to the first conductive member 60 having conductivity. The first conductive member 60 is a bracket, a door outer panel constituting a door outer plate, or the like, and is made of a metal having a high electrical resistivity (about 1 × 10 ⁻⁷ Ω · m) such as iron, platinum, or tin. Use. Between the housing 74 and the first conductive member 60, a second conductive member 61 having conductivity is disposed. The second conductive member 61 is made of a metal having a low electrical resistivity (about 1 × 10 ⁻⁸ Ω · m) such as aluminum, gold, copper, or silver. Each conductive member is selected so that the electrical resistivity of the first conductive member 60 is equal to or greater than that of the second conductive member 61.

In the above-described configuration, the second conductive member 61 having the same electrical resistivity as the first conductive member 60 or lower than the first conductive member 60 is used. The greater the electrical resistivity, the greater the change (eg, increase) in coil impedance. When the second conductive member 61 is disposed between the coil 72 and the first conductive member 60, the amount of increase in impedance is largely determined by the second conductive member 61. With the above configuration, an increase in impedance due to the first conductive member 60 can be suppressed.

By using iron as the first conductive member 60, the configuration of the present disclosure can be applied when a coil is placed close to a body that mainly uses iron. Further, by using aluminum as the second conductive member 61, the configuration of the present disclosure can be realized at a relatively low cost, and an increase in the weight of the coil unit can be suppressed. Further, aluminum may be used as the first conductive member 60.

In FIG. 3, the cross sections of the bobbin 71 and the coil 72 are substantially circular, but they may be substantially rectangular. Further, the cross section of the housing 74 is substantially rectangular, but may be substantially circular. The cross section of the housing 74 may have a shape that matches the cross sections of the bobbin 71 and the coil 72.

The distance between the coil 72 and the second conductive member 61 (for example, D in FIG. 3) is preferably close to zero. The coil 72 and the second conductive member 61 may be in contact with each other as long as the insulation between the two can be ensured. Thereby, the enlargement (especially height direction: the up-down direction of drawing) of a housing | casing can be prevented.

In FIG. 2, the second conductive member 61 covers the bottom surface of the outer wall portion of the casing 74, that is, the entire facing surface facing the first conductive member 60. Depending on the material (that is, electrical resistivity) of each conductive member, the second conductive member 61 is in the direction of the central axis of the coil 72 on the bottom surface of the casing 74 as in the second conductive member 62 in FIG. An area corresponding to about 2/3 of the length L may be covered. Like the second conductive member 63 of FIG. 5, the second conductive member 61 covers a region corresponding to about ½ of the length L in the central axis direction of the coil 72 on the bottom surface of the housing 74. Also good.

Further, the second conductive member 62 may be arranged so as to cover only a range where the coil 72 or the core 73 faces the first conductive member 60. The range in which the coil 72 faces the first conductive member 60 is a range indicated by L11 in FIG. 2 and L12 in FIG. The range in which the core 73 faces the first conductive member 60 is a range indicated by L21 in FIG. 2 and L22 in FIG.

The arrangement range of the second

conductive members

61, 62, 63 may be determined by the characteristics of the coil 72 and the first conductive member 60. The arrangement range of the second

conductive members

61, 62, 63 may be determined by the distance between the coil 72 and the first conductive member 60 (for example, D in FIG. 3). That is, it is determined according to the amount of increase in impedance of the antenna 42 by the first conductive member 60. Thereby, the antenna 42 can be adjusted to a desired impedance.

As shown in FIG. 6, after determining the position of the coil 72 in the housing 74 in the state of FIG. 2, a potting material (sealing material) 75 may be injected into the housing 74. In addition to the method of injecting the potting material 75, the coil 72 and the core 73 may be included in insert molding.

As shown in FIGS. 2 to 6, the coil 72 is housed in a housing 74, and the second

conductive members

61, 62, 63 are attached to the outer wall of the housing 74 facing the first conductive member 60. . With this configuration, the antenna and the second

conductive members

61, 62, and 63 can be integrated to reduce the number of components. Moreover, attachment to the first conductive member 60 is also facilitated. In addition, the distance between the coil 72 and the second

conductive members

61, 62, 63 can be kept constant, and even if the distance between the coil 72 and the first conductive member 60 varies when the antenna is mounted, the amount of change in impedance. Can be suppressed.

As shown in FIG. 7, the second conductive member 64 may be attached to the inner wall surface of the bottom surface of the housing 74. As shown in FIG. 7, the coil 72 is housed in a housing 74, and the second conductive member 64 is attached to the inner wall surface of the outer wall of the housing 74 facing the first conductive member 60. With this configuration, the number of parts can be reduced by integrating the antenna and the second

conductive members

61, 62, 63, 64. Moreover, attachment to the first conductive member 60 is also facilitated.

The second

conductive members

61, 62, 63, 64 may be attached to both the bottom surface of the outer wall portion of the housing 74 and the inner wall surface of the bottom surface of the housing 74. That is, in FIG. 7, the second conductive member 61 is disposed between the bottom surface of the housing 74 and the first conductive member 60 as shown in FIG. 2. That is, the coil 72 is housed in the housing, and the second

conductive members

61, 62, 63, and 64 are the surfaces of the outer wall of the housing facing the first conductive member 60 and the first conductive member 60 of the housing. May be attached to the inner wall surface of the outer wall opposite to. Also with this configuration, an increase in impedance due to the first conductive member 60 can be suppressed.

As shown in FIG. 8, the antenna 42 may not be stored in the housing 74.

As shown in FIG. 9, the antenna 42 can be represented as a series resonant circuit of L (inductance), C (capacitance), and two R (resistance of the coil), for example. For example, in the state of FIG. 2, when the antenna 42 is directly attached to the first conductive member 60, that is, when the second conductive member (61 etc.) is not disposed, the equivalent circuit is connected to both ends of the RLC series resonant circuit. In this case, two Rf, which are the resistance components of the first conductive member 60, are connected in series. Accordingly, the impedance of the antenna 42 is increased by the increase of the two Rf. P is a power supply for the antenna 42.

FIG. 10 shows the relationship between the distance between the coil 72 and the first conductive member 60 (corresponding to D in FIG. 3) and the impedance Z of the antenna 42 when iron is used for the first conductive member 60. As the distance D decreases, the impedance Z tends to increase. For example, the impedance Z when the distance D is 1 mm is 25Ω. At this time, a voltage required to flow 2 A of current (hereinafter referred to as “antenna current”) flowing through the coil 72 is 50V. This is supplied from the power supply P.

In the case of a vehicle, the power supply P is supplied from a battery. When boosting the battery voltage with the power supply P, if the battery voltage is 12V and the boosting efficiency is 80%, it is necessary to supply a current of about 10.4 A from the battery.

Also, the impedance Z when the distance D is 15 mm is 5Ω. At this time, the voltage required to flow the antenna current of 2A is 10V. Therefore, a current of about 2.1 A may be supplied from the battery. However, as the distance D increases, the mounting position of the antenna 42 increases.

As described above, the battery current consumption increases as the impedance increases. In particular, the electronic key system operates even when the prime mover stops and the battery is not charged, which causes an increase in dark current.

FIG. 11 shows an equivalent circuit of the antenna 42 of the configuration of the present disclosure (for example, FIG. 2). The equivalent circuit is a series of two resistance circuits in which Rf, which is the resistance component of the first conductive member 60, and Ra, which is the resistance component of the second conductive member 61, are connected in parallel to both ends of the RLC series resonance circuit of FIG. It will be connected. When iron is used as the first conductive member 60 and aluminum is used as the second conductive member 61, Ra is about 1/5 of Rf. Therefore, the combined resistance of the resistance circuit is Rf / 6, and the impedance of the antenna 42 is reduced. The fluctuation is smaller than that in the configuration of FIG.

According to the inventor's experiment, the impedance of the antenna 42 is about 16.8% of the configuration of the comparative example in which the second conductive member 61 is not used in the configuration of FIG. 2, and the configuration of the comparative example in the configuration of FIG. The configuration of FIG. 5 is about 27.2%, which is about 68.0% of the configuration of the comparative example, and the effect of reducing impedance appears. Further, the larger the area of the second conductive member 61, the greater the effect of reducing impedance.

Even if aluminum is used for the first conductive member 60 and the second conductive member 61, the combined resistance becomes Ra / 2, so that an increase in antenna impedance can be suppressed.

Although the present disclosure has been described based on the embodiments, it is understood that the present disclosure is not limited to the embodiments and structures. The present disclosure includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms including only one element, more or less, are within the scope and spirit of the present disclosure.

Although the embodiments of the present invention have been described above, these are merely examples, and the present invention is not limited to these embodiments, and the knowledge of those skilled in the art can be used without departing from the spirit of the claims. Various modifications based on this are possible.

Claims

A coil (72);
Conductivity disposed between the coil and the conductive first conductive member (60) disposed adjacent to the coil to suppress a change in impedance of the coil by the first conductive member. A second conductive member (61, 62, 63, 64) having
A coil unit comprising:
The coil unit according to claim 1, wherein an electrical resistivity of the second conductive member is equal to or lower than an electrical resistivity of the first conductive member.
The coil unit according to claim 1 or 2, wherein the first conductive member is made of iron, and the second conductive member is made of aluminum.
The coil is housed in a housing (74);
The coil unit according to any one of claims 1 to 3, wherein the second conductive member (61, 62, 63) is attached to a surface of the outer wall of the housing facing the first conductive member. .
The coil is housed in a housing (74);
The coil unit according to any one of claims 1 to 4, wherein the second conductive member (64) is attached to an inner wall surface of the outer wall of the housing facing the first conductive member.
The coil unit according to any one of claims 1 to 5, wherein the coil is used for an antenna (42, 44, 30a) of a communication device using a long wave band.
A portable key (3) possessed by the user and an in-vehicle device mounted on the vehicle, and the portable key is collated by wireless communication between the portable key and the in-vehicle device, and based on the collation result In an electronic key system that performs predetermined control,
The coil is
An antenna (42, 44) of a verification request transmission unit (41, 43) provided in the in-vehicle device, for transmitting the verification request signal to the portable key (3); and
The coil unit according to any one of claims 1 to 6, wherein the coil unit is provided in the portable key and used for an antenna (30a) of a verification request receiving unit (30) that receives the verification request signal.
Mobile key (3),
An in-vehicle device mounted on the vehicle;
ECU (4) that performs collation of the portable key by wireless communication between the portable key and the in-vehicle device, and performs predetermined control based on the collation result,
The in-vehicle device includes an antenna (42, 44) of a verification request transmission unit (41, 43) that transmits the verification request signal to the portable key (3),
The portable key includes an antenna (30a) of a verification request receiving unit (30) that receives the verification request signal.
Both the antenna of the said collation request | requirement transmission part and the said antenna of the said collation request | requirement reception part are electronic key systems containing the coil unit of any one of Claim 1 thru | or 6.