JP3259907B2 - Vehicle sensor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle sensor installed in a parking lot, for example, for detecting the presence or absence of a vehicle.

[0002]

Conventionally, as a vehicle sensor for detecting the presence or absence of a vehicle in, for example, a parking lot, a sensor using light, ultrasonic waves, or microwaves has been provided. That is, a vehicle sensor using light, for example, at the entrance of a parking lot, a light emitting device and a light receiving device are installed facing each other, and it is detected whether light emitted from the light emitting device is received by the light receiving device. As a result, the presence or absence of a vehicle is detected. In addition, vehicle sensors using ultrasonic waves and microwaves, for example, on the ceiling of a parking lot,
An oscillating device that oscillates ultrasonic waves or microwaves is installed, and the presence or absence of a vehicle is detected by detecting whether or not the ultrasonic waves or microwaves oscillated from the oscillating device are reflected.

However, in the case of using light, there is a possibility that an erroneous detection may occur due to the influence of disturbance light such as sunlight. Also, in the case of using an ultrasonic wave or a microwave, there is a possibility that an erroneous detection may be caused due to the influence of the wind, and in this case, the ultrasonic wave or the microwave may be generated by a curved surface portion of a vehicle body. There is a risk that the light will be reflected in the wrong direction, which may also lead to erroneous detection.

Therefore, a vehicle sensor has been proposed which detects the presence or absence of a vehicle using a magnetic flux instead of light, ultrasonic waves or microwaves. The vehicle sensor using this magnetic flux has a transmission coil and a reception coil installed at a predetermined interval, and when the vehicle is parked, the magnetic flux generated from the transmission coil is transmitted to a metal part (steel plate) of the vehicle. ) Is transmitted and received by the receiving coil, so that the presence or absence of the vehicle is detected by detecting a change in the reception level of the magnetic flux received by the receiving coil. In this case, since no light, ultrasonic waves or microwaves are used, the detection accuracy can be improved.

[0005] In this case, since the transmission coil and the reception coil described above utilize the fact that the magnetic flux transmits through the metal part of the vehicle, they need to be installed at a position somewhat closer to the vehicle. May be installed on the ground. However, when the transmitting coil and the receiving coil are installed on the ground, there is a possibility that the traffic may be obstructed.
Further, since there is a possibility that the tire of the vehicle may be damaged by contacting the transmission coil and the reception coil, it is necessary to store and protect the transmission coil and the reception coil inside the case. In that case, the case is considered to be made of plastic because it is required to pass a magnetic flux.However, plastic is not sufficiently strong, so that the inside of the case is filled with, for example, foamed hard urethane. For example, it is necessary to increase the strength. However, this requires a filling operation of foamed hard urethane in the production, which causes a reduction in workability.

[0006] Even if the transmitting coil and the receiving coil are housed in a plastic case and installed on the ground, they receive sunlight, for example, unless the parking lot has a roof. However, there is also a problem that the case is deteriorated under the influence of sunlight.

Therefore, it is conceivable that the transmitting coil and the receiving coil are not installed on the ground, but are installed on the ground. However, also in this case, in order to protect the transmission coil and the reception coil from moisture in the ground, it is necessary to house the transmission coil and the reception coil inside the case. When installing it inside, it is necessary to dig up the ground, and there is also a problem that a cost (construction cost) is required.

The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to improve the detection accuracy and to install the apparatus on the ground (ground). It is an object of the present invention to provide a vehicle sensor that is not likely to be damaged even if the vehicle comes into contact with the case and that does not deteriorate the case due to the influence of sunlight.

[0009]

According to the present invention, there is provided a vehicle sensor comprising:
A transmission device in which a transmission coil that generates a magnetic flux when an oscillation frequency in a predetermined range is provided is disposed inside the case,
A receiving device in which a receiving coil capable of receiving a magnetic flux generated from the transmitting coil is disposed inside a case, and detecting means for detecting the presence or absence of a vehicle based on a change in magnetic flux received by the receiving coil. The case of the transmission device and the case of the reception device are formed of metal, and the oscillation frequency in a predetermined range given to the transmission coil is such that the magnetic flux generated from the transmission coil is received by the reception coil. particular response, the damping rate of the received magnetic flux due to eddy current loss generated in the case of the case and the receiver of the transmission device is set to a value in the range of a predetermined level or less, the transmission coil and the receiving coil, one side Department
Constructs a shape that is narrower than the other side that is substantially perpendicular to this
So that the one side portion is inclined with respect to the horizontal plane
There is a feature in the configuration (claim 1).

[0010] According to the vehicle sensor having the above-described configuration, in the transmission device, when a predetermined range of oscillation frequency is applied to the transmission coil, a magnetic flux is generated from the transmission coil. Then, in the receiving device, when the magnetic flux generated from the transmitting coil is received by the receiving coil,
A change in the received magnetic flux is detected, and the presence or absence of the vehicle is detected based on the detection result.

[0011] However, this device does not use light, ultrasonic waves or microwaves, but uses a magnetic flux to detect the presence or absence of a vehicle, so that the detection accuracy can be improved. Further, since the case of the transmitting device and the case of the receiving device are formed of metal, the strength is large as compared with the case where the case is formed of plastic, and even if the vehicle comes into contact with the case, there is no possibility of damage. ,Also,
The case does not deteriorate due to the influence of sunlight. This makes it possible to install the transmitting device and the receiving device on the ground (ground).

Here, as described above, since the case of the transmitting device and the case of the receiving device are formed of metal, when the magnetic flux generated from the transmitting coil is received by the receiving coil, the case is required. , An eddy current is generated and an eddy current loss occurs. In this case, the eddy current loss is represented by the following equation.

[0013]

(Equation 1)

Ω: Eddy current loss f: Oscillation frequency κ: Conductivity of case μ: Magnetic permeability of case As is clear from the above equation, the eddy current loss ω is the oscillation frequency f
Is proportional to the square of.

Here, the present invention focuses on this point, and changes the oscillation frequency within a predetermined range given to the transmission coil to the transmission device in accordance with the fact that the magnetic flux generated from the transmission coil is received by the reception coil. The value is set to a value within a range in which the attenuation rate of the received magnetic flux due to the eddy current loss generated in the case and the case of the receiving device is equal to or less than a predetermined level. Thus, even if an eddy current loss occurs, the eddy current loss does not adversely affect the detection.

[0016]

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS. First, in FIG. 1, a vehicle sensor 1 includes a transmitting device 2 and a receiving device 3, and the transmitting device 2 and the receiving device 3 are installed at a predetermined interval on the ground of a parking lot, for example. I have. Note that, in FIG.

The case 4 of the transmitting device 2 is made of stainless steel, and a transmitting coil unit 5 and a transmitting circuit board 6 are disposed inside the case 4. The transmitting coil unit 5
As shown in FIG. 2, a transmission coil 8 is wound around a long cylindrical magnetic core 7. Further, on the transmission circuit board 6, an oscillation circuit 9 and a transmission circuit 10 (all shown in FIG. 3) are configured by various electronic components.

The case 11 of the receiving device 3 is made of stainless steel, similarly to the case 4 of the transmitting device 2 described above, and the receiving coil unit 12 and the receiving circuit board 13 are disposed inside the case 11. Have been. The reception coil unit 12 is configured by a reception coil 15 being wound around a long cylindrical magnetic core 14, similarly to the transmission coil unit 5 described above (see FIG. 2). Further, on the receiving circuit board 13, a receiving circuit 16, an amplifier circuit 17, a band-pass filter 18, and a detecting circuit 19 as detecting means (all shown in FIG. 3) are constituted by various electronic components.

In this case, the transmitting coil unit 5 and the receiving coil unit 12 are respectively provided with a side surface 5a and a side surface 12a.
The width of a (indicated by d1 in FIG. 2) is smaller than the width of the side part 5b and the side part 12b (indicated by d2 in FIG. 2), and the side part 5a and the side part 12a The transmission coil unit 5 and the reception coil unit 12 (the magnetic cores 7 and 14) are imaginary extensions (B in FIG. 1). Are shown) so that they intersect. This is to improve the reception efficiency of the magnetic flux when the magnetic flux generated from the transmitting coil 8 of the transmitting coil unit 5 is received by the receiving coil 15 of the receiving coil unit 12.

The transmission coil unit 5 and the reception coil unit 1
2, the side surface portion 5a and the side surface portion 12a
Correspond to one side portion in the present invention, and the side portion 5b and the side portion 12b correspond to the other side portion in the present invention. Also, according to this, the transmission circuit board 6
The receiving circuit board 13 is also inclined and installed so as to have the inclination angle α.

Next, the electrical configuration of the transmitting device 2 and the receiving device 3 will be described with reference to FIG. First, in the transmission device 2, the oscillation circuit 9 outputs a pulse signal having an oscillation frequency within a predetermined range to the transmission circuit 10. When the transmission circuit 10 receives the pulse signal from the oscillation circuit 9, the oscillation circuit 9 outputs the pulse signal. A transmission signal is generated based on the given pulse signal, and the transmission signal is output to the transmission coil unit 5. In addition, the transmission coil unit 5
When a transmission signal is supplied from the transmission circuit 10, the transmission coil 8 converts the supplied transmission signal from an electric signal to a magnetic signal, and generates a magnetic flux from the transmission coil 8.

In the receiving device 3, the receiving coil unit 12
Is capable of receiving the magnetic flux generated from the transmission coil 8 of the transmission device 2 by the reception coil 15, and when the magnetic flux is received by the reception coil 15, converts the received magnetic flux (reception magnetic flux) from a magnetic signal to an electric signal. Conversion and reception circuit 16
Output.

The reception circuit 16 outputs a reception signal corresponding to the amount of magnetic flux received by the reception coil section 12 to the amplifier circuit 17. The amplifier circuit 17 receives the reception signal from the reception circuit 16. Then, the received signal is amplified and output to the band-pass filter 18.

The band-pass filter 18 is connected to the amplifier circuit 1
When the amplified received signal is supplied from the receiver 7, unnecessary noise components are removed from the amplified received signal and output to the detection circuit 19. When a received signal from which a noise component has been removed is provided, the reception level of the received signal is compared with a preset reference level, and when the reception level is higher than the reference level, a detection signal is output. It has become.

As shown in FIG. 4, the transmitting device 2 and the receiving device 3 configured as described above are installed in a predetermined parking area 20 on the ground of a parking lot.
When the vehicle 1 is parked in the parking area 20, the vehicle 1 is covered by the vehicle 21. In this case,
The transmitting device 2 and the receiving device 3 may be arranged side by side in the longitudinal direction of the vehicle 21 as shown in FIG. 4A, or the width of the vehicle 21 as shown in FIG. They may be juxtaposed in the direction. The driving power is supplied to the transmitting device 2 and the receiving device 3 via a power cable (not shown). In this case, the power cable is buried underground. is there.

Next, the operation of the above configuration will be described with reference to FIGS. First, when the vehicle 21 is not parked in the parking area 20, in the transmission device 2, when a pulse signal is output from the oscillation circuit 9 to the transmission circuit 10, the transmission circuit 10 generates a pulse signal based on the pulse signal. Thus, a transmission signal is generated, and the transmission circuit 10 outputs the transmission signal to the transmission coil unit 5. Then, in the transmission coil unit 5, the transmission signal is converted from the electric signal to the magnetic signal by the transmission coil 8, and the magnetic flux from the transmission coil 8 in FIG.
It is generated in a range shown as a transmission area P1 and a transmission area P2.

On the other hand, in the receiving device 3, the transmitting device 2
When a part of the magnetic flux generated in the range indicated by the transmission area P1 and the transmission area P2 reaches the range indicated by the reception area D1 and the reception area D2 in FIG. The received magnetic flux is converted from a magnetic signal into an electric signal, and a reception signal corresponding to the amount of magnetic flux received by the reception coil unit 12 from the reception circuit 16 is output to the amplifier circuit 17. And the amplifier circuit 1
At 7, the received signal is amplified, and the amplified received signal is output from the amplifier circuit 17 to the band-pass filter 18. The band-pass filter 18 removes unnecessary noise components from the amplified received signal. Then, a reception signal from which unnecessary noise components have been removed is output from the band-pass filter 18 to the detection circuit 19, and the detection circuit 19 compares the reception level of the reception signal with a reference level.

At this time, as shown in FIG.
The magnetic flux generated in the range shown in the transmission area P1 does not reach the range shown in either the reception area D1 or the reception area D2, and only the magnetic flux generated in the range shown in the transmission area P2 from the transmission device 2 is received. D2. Therefore, the amount of magnetic flux received by the reception coil unit 12 is relatively small, that is, the reception level of the reception signal does not become higher than the reference level,
No detection signal is output from the detection circuit 19.

On the other hand, when the vehicle 21 is in the parking area 20
As shown in FIG. 6, the magnetic flux generated from the transmission device 2 in the range shown in the transmission area P1 is transmitted to the metal part (steel plate) of the bottom 21a of the vehicle 21 and the reception area D1 is parked.
That is, in addition to the magnetic flux generated from the transmitting device 2 in the range shown in the transmission area P2 to the range shown in the receiving area D2, the magnetic flux generated from the transmitting device 2 to the range shown in the transmission area P1 Generated in the receiving area D2. Therefore, the amount of magnetic flux received by the receiving coil unit 12 is relatively large,
That is, the reception level of the reception signal becomes higher than the reference level, and the detection signal is output from the detection circuit 19.

As described above, when the vehicle 21 is not parked in the parking area 20, the amount of magnetic flux received by the receiving coil unit 12 is relatively small, and the detection signal is not output from the detection circuit 19. When the vehicle 21 is parked in the parking area 20, the receiving coil unit 12
Is relatively large, the detection circuit 19
Since the detection signal is output from the vehicle, it is possible to determine whether the vehicle 21 is parked in the parking area 20 by determining whether the detection signal is output.

As described above, since the case 4 of the transmitting device 2 and the case 11 of the receiving device 3 are both made of stainless steel, the magnetic flux generated from the transmitting coil 8 is received by the receiving coil 15. In doing so, an eddy current is generated in the case 4 of the transmitting device 2 and the case 11 of the receiving device 3, and eddy current loss occurs. In this case, the eddy current loss is represented by the following equation.

[0033]

(Equation 2)

Ω: Eddy current loss f: Oscillation frequency κ: Conductivity of case μ: Magnetic permeability of case As is apparent from the above equation, the eddy current loss ω is the oscillation frequency f
Is proportional to the square of.

Now, the inventors have paid attention to this point, and by selecting a material having a small electric conductivity κ and a small magnetic permeability μ as the material of the case and reducing the oscillation frequency, the case of the transmitting device 2 is reduced. 4 and the eddy current loss ω occurring in the case 11 of the receiver 3 are reduced.

First, the inventors made the case material
Since the conductivity κ and the magnetic permeability μ of the main metal are as shown in FIG. 7, stainless steel having the smallest conductivity κ was selected.

Next, when selecting the oscillation frequency, the inventors set the oscillation frequency to 1 kHz, 2 kHz, 5 kHz.
Hz, 10 kHz, and 20 kHz, the reception voltage of the reception signal in a state where the case 4 of the transmission device 2 and the case 11 of the reception device 3 are removed, respectively.
And the reception voltage of the reception signal in the state where the case 4 of the receiver 3 and the case 11 of the receiver 3 were mounted, and the attenuation rate was calculated from the measurement result of the reception voltage. FIG. 8 is a table showing the relationship between the oscillation frequency and the attenuation factor, and FIG.
7 is a graph showing a relationship between an oscillation frequency and an attenuation rate. As is apparent from FIGS. 8 and 9, it can be seen that the attenuation rate decreases as the oscillation frequency decreases.

On the other hand, it is known that the power consumption increases as the oscillation frequency decreases. FIG. 10 is a table showing the relationship between the oscillation frequency and the power consumption, and FIG. 11 is a graph showing the relationship between the oscillation frequency and the power consumption.

From the above, the present inventors consider the optimum value of the oscillation frequency in consideration of the correlation between the attenuation rate and the power consumption. In this case, the frequency component of the engine noise of the vehicle 21 is 1 kHz to Since it is 2 kHz, 1 kHz
２2 kHz was avoided and set to 5 kHz.

As described above, according to the present embodiment, the transmission coil unit 5 that generates the magnetic flux and the reception coil unit 12 that can receive the magnetic flux generated from the transmission coil unit 5 are provided. Since it is configured to detect whether or not the vehicle 21 is parked based on the change in the amount of magnetic flux received, it is possible to detect the presence or absence of the vehicle 21 without using light, ultrasonic waves or microwaves. Thus, the detection accuracy can be improved.

A case 4 for housing the transmission coil unit 5
In addition, since the case 11 for storing the receiving coil unit 12 is made of stainless steel, the strength is large as compared with the case made of plastic, and even if the vehicle 21 comes into contact with the case, there is no possibility of breakage. The transmission device 2 and the reception device 3 can be installed on the ground without deterioration of the case.

When a magnetic flux is generated from the transmission coil unit 5, the oscillation frequency given to the transmission coil 8 is set to 5 k.
Hz, even if an eddy current loss occurs in the case 4 of the transmission device 2 and the case 11 of the reception device 3, the attenuation rate of the reception voltage caused by the eddy current loss is set to a predetermined level (for example, 50%) or less. The power consumption can be suppressed to some extent.

Further, since the oscillation frequency applied to the transmission coil 8 is set to 5 kHz, the eddy current loss generated in the vehicle 21 can be reduced, and the decrease in the amplitude of the magnetic flux generated from the transmission coil unit 5 is suppressed. That is, the attenuation of the received magnetic flux can be suppressed, and the detection accuracy can be prevented from lowering.

Next, another embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted. Hereinafter, different parts will be described. The transmission coil unit 31 shown in the other embodiment is configured by winding a transmission coil 33 around a columnar magnetic core 32, and the reception coil unit 34 is similar to the transmission coil unit 31 described above. The receiving coil 36 is wound around a cylindrical magnetic core 35.
In this case, the transmission coil unit 31 and the reception coil unit 3
The width of the peripheral surface portion 31a and the peripheral surface portion 34a in FIG.
In the transmission coil unit 5 and the reception coil unit 12 described in the above-described embodiment.
a and the width of the side surface portion 12a (shown as d1 in FIG. 2), and the width of the side surface portion 5b and the side surface portion 12b (see FIG. 2).
(Indicated by d2 in the middle). In the transmitting coil 8, the receiving coil 15, the transmitting coil 33, and the receiving coil 36, the areas (effective areas) that contribute to the transmission and reception of the magnetic flux are equal. According to such another embodiment, the same operation and effect as those of the above-described embodiment can be obtained.

At this time, comparing the above-described embodiment with another embodiment, the embodiment has the following advantages. That is, in FIG. 13, the left side shows the configuration of the transmission device 2 of one embodiment, and the right side shows the configuration of the transmission device of another embodiment. In this case, in the embodiment, since the transmitting coil section 5 is configured to have a long columnar shape as a whole,
Since a is inclined so as to have the inclination angle α with respect to the horizontal plane, the overall height can be made lower than that of the other embodiments (the difference is indicated by h in FIG. 13). Since the height of the transmitting coil unit 5 can be reduced in this way, the height of the case 4 of the transmitting device 2 can also be lower than those of the other embodiments. Then, it is possible to suppress an obstacle to traffic by that much, and it is possible to further reduce the possibility that the vehicle 21 comes into contact. Of course, the receiving device 3 is the same as this.

The present invention is not limited to the embodiment described above, but can be modified or expanded as follows. The case of the transmitting device and the case of the receiving device are not limited to a configuration in which the case of the transmitting device and the case of the receiving device are separated from each other.

The transmission coil section and the reception coil section are not limited to the configuration having the shape of an elongated cylinder as a whole, but may have the configuration of an elliptical cylinder or a rectangular parallelepiped. The material of the case is not limited to stainless steel, and other metals may be used as long as they do not interfere with detection.

[0048]

As is apparent from the above description, according to the vehicle sensor of the first aspect, the transmitting coil for generating the magnetic flux and the receiving coil capable of receiving the magnetic flux generated from the transmitting coil are provided. Since the presence or absence of the vehicle is detected based on the change in the amount of magnetic flux received by the receiving coil, the detection accuracy can be detected without using light, ultrasonic waves or microwaves in detecting the presence or absence of the vehicle. Can be improved.

Further, since the case for housing the transmitting coil and the case for housing the receiving coil are made of metal, the strength is greater than that of the plastic case, and there is no risk of breakage even if the vehicle comes into contact. ,Also,
The case is not degraded by the influence of sunlight, and this makes it possible to install the transmitting device and the receiving device on the ground (ground).

Further, when a magnetic flux is generated from the transmission coil, the oscillation frequency given to the transmission coil is changed according to the fact that the magnetic flux generated from the transmission coil is received by the reception coil. Since the attenuation rate of the received magnetic flux due to the eddy current loss generated in the case is set to a value within a predetermined level or less, even if the eddy current loss occurs, the eddy current loss does not adversely affect the detection.

Further , the transmitting coil and the receiving coil are
Since one side is configured to be narrower than the other side, and the one side is inclined with respect to the horizontal plane, the height of the transmitting coil and the receiving coil can be reduced, and Accordingly, the height of the case of the transmitting device and the height of the case of the receiving device can be reduced, so that it is possible to suppress an obstacle to the traffic of the vehicle, and to further reduce the possibility of the vehicle coming into contact. be able to.

[Brief description of the drawings]

FIG. 1, showing an embodiment of the present invention, is a longitudinal side view showing a state of being installed on the ground.

FIG. 2 is a plan view (a), a front view (b), and a side view (c) of a transmission coil unit and a reception coil unit.

FIG. 3 is a block diagram showing an electrical configuration.

FIG. 4 is a diagram showing a state where the vehicle is installed in a parking area.

FIG. 5 is a view showing an operation (part 1);

FIG. 6 is a view showing an operation (part 2);

FIG. 7 is a diagram showing conductivity and magnetic permeability;

FIG. 8 is a table showing attenuation rates with respect to oscillation frequencies;

FIG. 9 is a graph showing an attenuation rate with respect to an oscillation frequency in a graph.

FIG. 10 is a table showing power consumption with respect to an oscillation frequency;

FIG. 11 is a graph showing power consumption with respect to an oscillation frequency.

FIG. 12 is a view corresponding to FIG. 2, showing another embodiment of the present invention.

FIG. 13 is a diagram showing a comparison between one embodiment and another embodiment.

[Explanation of symbols]

In the drawing, 1 is a vehicle sensor, 2 is a transmitting device, 3 is a receiving device, 4 is a case, 8 is a transmitting coil, 11 is a case, 15
Is a receiving coil, 19 is a detecting circuit (detecting means), 21 is a vehicle, 33 is a transmitting coil, and 36 is a receiving coil.

Continuation of the front page (56) References JP-A-9-251081 (JP, A) JP-A-6-317674 (JP, A) JP-A-9-245296 (JP, A) JP-A-3-119207 (JP) , U) (58) Field surveyed (Int.Cl. ⁷ , DB name) G01V 3/10

Claims (1)

(57) [Claims] 1. A transmission device comprising: a transmission coil that generates a magnetic flux when an oscillation frequency within a predetermined range is provided; and a reception coil capable of receiving a magnetic flux generated from the transmission coil. And a detecting means for detecting the presence or absence of a vehicle based on a change in magnetic flux received by the receiving coil. The case of the transmitting device and the case of the receiving device are formed of metal. And the oscillation frequency in a predetermined range given to the transmission coil is:
A range in which the attenuation rate of the received magnetic flux due to the eddy current loss generated in the case of the transmitting device and the case of the receiving device is equal to or less than a predetermined level in response to the magnetic flux generated from the transmitting coil being received by the receiving coil. is set to a value which the transmitting coil and the receiving coil, on one side portion which
If it is configured to be narrower than the other side that is substantially orthogonal,
In addition, the one side portion is inclined with respect to a horizontal plane.
Characteristic vehicle sensor.