JPS6224306B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention arranges a transmitting coil and a receiving coil near a rail, and prevents the coupling disturbance caused between the transmitting coil and the receiving coil by wheels running on the rail. The present invention relates to a wheel detection device that detects wheels.

FIG. 1 is an explanatory diagram of a conventional wheel detection device.
As shown in the figure, the conventional wheel detection device disposes a transmitting coil 4 driven at the oscillation frequency of an oscillator 2 via an amplifier 3 on one side of a rail 1, and on the other side with the rail 1 in between. to receive coil 5
It has a structure with . 6 is an amplifier, and 7 is a level judger.

In the wheel detection device having the above configuration, the angle of intersection of the magnetic flux a of the transmitting coil 4 with respect to the coil axis b of the receiving coil 5 is θ, and the induced voltage induced in the receiving coil 5 is
If the maximum value of e ₁ is E ₁ , the induced voltage e ₁ is e ¹ =
E ₁ cosθ……(1). Induced voltage E ₁ and intersection angle θ
differs between when the wheel is present between the transmitting and receiving coils 4 and 5 and when it is not, so the induced voltage e ₁
will also change depending on the presence or absence of wheels. If the induced voltage, which was e ₁ when the wheel was not present, changes by △e ₁ because the wheel has entered, the rate of change ε can be calculated by attaching a △ symbol to the change in each element and calculating ε
= △e ₁ /e ₁ = (△E ₁ /E ₁ ) + (△cosθ/cosθ).

This change in induced voltage is amplified by a receiving amplifier 6, and then taken out as wheel detection information V via a level determiner 7 which produces an output V when the output of the receiving amplifier 6 exceeds a threshold voltage.

The above-mentioned intersection angle θ needs to be set and adjusted to various angles in order to extract the induced voltage according to the purpose of use of the wheel detection device. This is done by adjusting the tilt angle. For example, the output voltage V (V≠0) of the level determiner 7 corresponding to the induced voltage e ₁ of the receiving coil 5 is made to correspond to the truth value 1, and the level determining device corresponding to the induced voltage e ₁ ≒0 of the receiving coil 5 is made to correspond to the truth value 1. Assuming that the output voltage V≒O of 7 corresponds to the truth value O, the output information of the wheel detection device is that when a wheel enters between the transmitting and receiving coils 4 and 5, the output signal changes from the truth value 1 to the truth value 0. information (below)
(hereinafter referred to as CT information) and information that changes from truth value 0 to truth value 1 (hereinafter referred to as OT information) may be required.

To obtain CT information, the receiving coil 5 is tilted so that the intersection angle θ becomes, for example, θ=π/2−α (α is a small value) in a state where no wheels are present. 5, the truth value is 1 in advance, that is, the output V (V
≠ 0) in the receiving coil 5 is generated, and when the wheel enters between the transmitting and receiving coils 4 and 5, the induced voltage -△ _{e 1 is} generated and the input of the receiving amplifier 6 is approximately By setting it to zero, the truth value becomes 0.
Take out the output voltage corresponding to .

Further, in order to obtain OT information, the receiving coil 5 is tilted so that the intersection angle θ becomes θ=π/2 in a state where no wheels are present. In this case, if there are no wheels between the transmitting and receiving coils 4 and 5, the receiving coil 5
Since there is almost no interlinking magnetic flux a, no induced voltage is generated (e ₁ ≈O), and the output voltage V of the level determiner 7 becomes V≈O corresponding to the truth value O. Next, when a wheel exists between the transmitting and receiving coils 4 and 5, the direction of the magnetic flux a changes depending on the wheel, and the intersection angle θ
changes by Δθ, an induced voltage is generated in the receiving coil 5, and an output voltage V corresponding to the truth value 1 is extracted.

The disadvantages of the above-mentioned wheel detection device are that it is easily influenced by the environmental conditions in which the transmitter/receiver coils 4 and 5 are installed, requires adjustment of the coil axis b on site, and is difficult to handle. That is, for example, the direction of the coil axis where the induced voltage becomes zero is affected by the non-uniformity of the position of the receiving coil 5 even in a space without rails. Furthermore, in the case of sandwiching rails, the magnetic field distribution near the receiving coil is not a uniform distribution that can be approximated as a transmitting coil as a dipole, and the axial direction of the coil where the induced voltage is zero depends on the installation environment conditions at the site. more susceptible to influence. Therefore, when actually installing the wheel detection device at a site, it is necessary to adjust the coil axis of the receiving coil 5 in accordance with the individual installation environment. However, on-site coil axis adjustment work was extremely troublesome and difficult, as not only was the work efficiency low, but slight variations in the direction of the coil axis could immediately cause fluctuations in the induced voltage. . The present invention eliminates the above-mentioned conventional drawbacks and
It is an object of the present invention to provide a highly reliable wheel detection device in which a receiving coil is easy to install and handle, and does not require much effort.

In order to achieve the above object, the present invention arranges a transmitting coil and a receiving coil with a rail between them, and prevents the disturbance of coupling between the transmitting coil and the receiving coil caused by wheels running on the rail. In a wheel detection device that detects a wheel, the receiving coil is a first receiving coil, a second receiving coil is arranged on the transmitting coil side, and a differential output between the first receiving coil and the second receiving coil is provided. It is characterized by a configuration in which the detection output is .

DESCRIPTION OF THE PREFERRED EMBODIMENTS The content of the present invention will be explained in detail below with reference to the accompanying drawings which are examples. FIG. 2 is an explanatory diagram of the arrangement of transmitting coils and receiving coils of the wheel detection device according to the present invention. As shown in the figure, in the present invention, the receiving coil includes a first receiving coil 5a placed between the sending coil 4 and the rail 1, and a second receiving coil 5b placed on the side of the sending coil 4. be done.

The first receiving coil 5a is positioned such that its coil axis _b1 is substantially parallel to the direction of the magnetic flux _a1 of the transmitting coil 4, and is substantially perpendicular to the rail tread surface. This arrangement direction is the magnetic flux a ₁ with respect to the coil axis b ₁
The intersection angle θ ₁ becomes θ ₁ =O or π, and as understood from equation (1), this is when the change in the induced voltage with respect to the axial fluctuation of the coil is the smallest.

The second receiving coil 5b is the same as the first receiving coil 5.
This is provided to take out the differential output between the a and the a and obtain the above-mentioned CT information or OT information.
Since the second receiving coil 5b is provided on the same side of the rail as the transmitting coil 4, it is hardly affected by the wheels on the rail 1.

Therefore, the voltage induced in the second receiving coil 5b by the magnetic flux a ₂ of the transmitting coil 4 has a constant value determined by the intersection angle θ ₂ between the coil axis b ₂ and the magnetic flux a ₂ according to equation (1). In this embodiment, θ ₂ =π or O is set so that the change in induced voltage with respect to axis fluctuation is minimized. At the same time, the induced voltages of the first receiving coil 5a and the second receiving coil 5b are in an opposite phase relationship.

Note that if the structure of the vehicle running on the rail 1 is low, the second receiving coil 5b may receive an inductive effect and the reception level may increase. Since things are not low, they can be practically ignored.

Furthermore, it is preferable to place the transmitting coil 4 on the outside of the rail 1 so as not to affect onboard equipment such as trains running on the rail 1, but if there is no such concern, it may be placed on the inside of the rail. It's okay.

Next, the circuit configuration for obtaining CT information and OT information for wheel detection using the transmitting and receiving coils arranged as described above will be explained in detail. In order to obtain CT information and OT information, differential outputs of the first receiving coil 5a and second receiving coil 5b are obtained, but in this case, when the electrical connection of both coils 5a and 5b is in series. There are also cases where the two are connected in parallel.

FIG. 3 is an electrical circuit connection diagram when both receiving coils 5a and 5b are connected in series. In the figures, the same reference numbers as in FIGS. 1 and 2 indicate the same components.

In order to obtain CT information in the wheel detection device described above, the induced voltage of the second receiving coil 5b is e _b1 , and the induced voltage of the first receiving coil 5a when there is no wheel between the transmitting and receiving coils 4 and 5a is e _a1 and the induced voltage of the first receiving coil 5a when the wheel approaches is e' _a1 , e _a1 + e _b1 = e ₁ ...... (2) and e' _a1 + e _b1 ≒ O ...... In order to satisfy (3), the first,
What is necessary is to determine the coupling between the second receiving coils 5a and 5b. Here e _b1 , e _a1 and e' _a1 are in opposite phase. In addition, to obtain OT information, connect the transmitting/receiving coils 4 and 5a to satisfy e _b1 + e _a1 = O (4) and e _b1 + e' _a1 = e (5).
and 5b. The relationship between the output of the receiving amplifier 6 and the cascaded level determiner 7 is as explained in FIG. 1.

Furthermore, speaking about the fail-self property of this wheel detection device, if the first and second receiving coils 5a and 5b, which are most essential for fail-safety, have a disconnection failure, the receiving circuit is not configured, so the output e=O. Fail-safety regarding the receiving coils 5a and 5b is ensured.

Next, FIG. 4 shows the first and second receiving coils 5a,
An example of an electric circuit connection diagram when 5b are connected in parallel is shown. In the figure, _T1 is a transformer for taking out the differential output of the first and second receiving coils 5a and 5b. The two input windings of the transformer _T1
First and second receiving coils 5a and 5b are connected to P 1 and P ₂ separately, respectively, and their differential outputs are taken out from the output winding side S ₁ . Input winding P ₁ of transformer T ₁
The winding ratio of P2 and _P2 is adjusted according to the unbalanced input voltage e so as to obtain an output corresponding to the above equations (2), (3), or (4) and (5).

Reference numeral 6 denotes a receiving amplifier circuit, which has sufficient linearity over an output level range wider than the upper and lower threshold voltages of a later-stage window comparator, which will be described later. 8 and 10 are rectifier circuits. 9 is a window comparator. The window comparator 9 is constituted by a feedback type oscillator having a lower limit value and an upper limit value with which oscillation can be continued with respect to the input power supply voltage (DC). That is, in this embodiment, the output level of the rectifier circuit 8 has a lower limit value and an upper limit value at which the oscillation operation can be continued, and the oscillation operation is performed with the active region between the lower limit value and the upper limit value.

In this case, the window comparator 9 connects the first and second receiving coils 5a,
5b unbalanced differential output, that is, the above equation (2) and
The output of the amplifier 6 and rectifier circuit 8 corresponding to (5) is in the active region and produces an oscillation output, but the balanced differential output, that is, the output of the above equations (3) and (4), is outside the active region. The lower limit value is set so that no oscillation output occurs.

Moreover, the upper limit value is the first and second receiving coils 5a,
5b is disconnected and the unbalanced differential output increases significantly, it is set to be outside the active region. Note that if both the first and second receiving coils 5a, 5b are disconnected, the output of the transformer _T1 disappears, so the window comparator 9 is out of the active region and does not operate.

When the window comparator 9 is in the active region, its oscillation output is rectified by the rectifier circuit 10, and a rectified output corresponding to the truth value 1 is taken out. On the other hand, when the window comparator 9 is outside the active region, no oscillation output is produced, so the truth value corresponds to 0. If the window comparator 9 is outside the active area, this includes a disconnection failure in the first and second receiving coils 5a and 5b, so the window comparator 9 detects disconnection in the first and second receiving coils 5a and 5b. This ensures fail-self against failures.

FIG. 5 shows a specific circuit example of the window comparator 9, and FIG. 6 shows an explanatory diagram of its operation. When the input power supply voltage V _s becomes V _s V _s1 , the transistors Q ₁ , Q ₂ , and Q ₃ sequentially turn on and off repeatedly, and the collector resistors R ₃ to _{R 6} are connected to the output terminal V _p .
Then, an oscillation output with a frequency determined by the junction capacitance of transistors Q ₁ , Q ₂ , and Q ₃ is extracted. On the other hand, when the input power supply voltage V _s becomes V _s V _s2 , the feedback voltage VF determined by the division ratio of the collector resistances R ₅ and R ₆ of the transistor Q ₃ becomes large, and the transistor Q ₁
, the oscillation operation will stop and the device will be out of the active region.

When using the window comparator shown in FIG. 5, the input power supply voltage V _s is applied by the rectifier circuit 8, and the rectified output V _R1 corresponding to the unbalanced differential outputs of the first and second receiving coils 5a and 5b. V _s1 V _R1 <
V _s2 , and the first and second receiving coils 5
The rectified output V _R2 corresponding to the unbalanced differential output when one of a and 5b is disconnected may be determined as V _R2 ≧V _s2 . Note that the window comparator shown in FIG. 5 is fail-safe in itself because it stops oscillating when its own circuit fails.

Next, in the wheel detection device shown in Fig. 4,
The operation when obtaining CT information and OT information will be explained.

First, when obtaining CT information, the rectified output of the window comparator 9 is taken out as the detection output.

If the wheel is not between the transmitting coil 4 and the first receiving coil 5a, the first and second receiving coils 5a, 5
The outputs of b are mutually unbalanced, and an unbalanced differential output is taken out from the transformer _T1 . This differential output is amplified by an amplifier 6 and then converted into a DC output by a rectifier circuit 8. The DC output of the rectifier circuit 8 is within the active region of the window comparator 9, and the window comparator 9 performs an oscillating operation.
The oscillation output is converted into a DC output by a rectifier circuit 10, and a DC output voltage V corresponding to a truth value of 1 is extracted. On the other hand, when a wheel is detected, the induced voltages in the first and second receiving coils 5a and 5b are balanced, and the differential output of the transformer _T1 becomes approximately equal to zero. As a result, the DC output given from the rectifier circuit 8 to the window comparator 9 becomes less than or equal to the lower limit of the active region of the window comparator 9, so the window comparator 9 stops its oscillation operation and an output corresponding to the truth value 0 is taken out. .

Next, the case of obtaining OT information will be explained.

When no wheels are detected, the induced voltages of the first and second receiving coils 5a and 5b are balanced, and the differential output of the transformer _T1 becomes almost zero. Therefore, the window comparator 9 is out of the active region, and the output becomes a truth value of 0.

Next, when a wheel is detected, the first receiving coil 5
Since the induced voltage of a decreases, the induced voltage between the first and second receiving coils 5a and 5b becomes unbalanced,
An unbalanced differential output is taken out from the transformer _T1 . This differential output is amplified by a receiving amplifier 6. The amplified output is given to a rectifier circuit 8. Since the DC output V _R1 of the rectifier circuit 8 satisfies V _s2 >V _R1 >S _s1 , the window comparator 9 enters the active region and the oscillation output is taken out. This oscillation output is converted into a DC output by the rectifier circuit 10, and an output V corresponding to the truth value 1 is taken out.

Furthermore, if one of the first and second receiving coils 5a, 5b is disconnected, the degree of unbalance between the two becomes significantly large, and the DC output V _R2 of the rectifier circuit 8 corresponding to the differential output of the transformer _T1 increases. Since V _R2 >V _s2 , the window comparator 9 is out of the active region and its oscillation operation stops. As a result, the logical output has a truth value of 0, ensuring fail-safety against coil disconnection.

By the way, for example, when the induced voltage e _b1 of the second receiving coil is constant, the relationship between this induced voltage e _b1 and the induced voltage e _a1 of the first receiving coil, and the differential output e of both induced voltages is as follows. It will look like Figure 7. In Fig. 7, the horizontal axis represents the induced voltage _{e a1 ,} and the vertical axis represents the differential output e (unbalanced output) between the induced voltages e _a1 and e _b1 . The output becomes a minimum value (zero) and a balanced output is taken out.

Here, if the unbalanced output e _L giving CT information is plotted on a graph, the corresponding induced voltage e _a1 of the first receiving coil will be e _a1 as is clear from FIG.
There are two points: =e _M and e _a1 =e _N . The difference between e _M and e _N is that the polarity of the change in the differential output e is different for the same amount of change in the induced voltage e _a1 .

That is, in FIG. 7, if the induced voltage e _a1 changes by +Δe _a1 at the point e _a1 =e _M , the differential output e changes by -Δe. On the other hand, at the point e _a1 =e _N , the differential output changes by +Δe for the same change in Δe _a1 . In this way, there are two ways of changing the unbalanced differential output set to a certain specific value.

In the above embodiments, FIGS. 3 and 4,
The explanation has been made on the assumption that when extracting CT information, an unbalanced point is set such that the differential output decreases. However, in FIG. 4, since the window comparator 9 has an upper limit in its active region, even if the unbalance point is set in the direction in which the change in differential output increases, it cannot output a detection output in the same way. It is clear that it can be done. Furthermore, in FIG. 3, if a configuration is adopted in which a rectifier circuit and a window comparator are sequentially connected to the output, it is clear that the same can be said in this case as well.

FIG. 8 shows another embodiment of the wheel detection device according to the present invention. The feature of this embodiment is that the transmitting coils 4 are spatially coupled to each other in FIG.
and the second receiving coil 5b are not spatially coupled but directly inductively coupled. In this case, the transmitting coil 4 is connected between both coils 4 and 5b.
A phase shifter and an attenuator corresponding to the amount of phase shift and attenuation between the first receiving coil 5a and the first receiving coil 5a are required instead of the spatial coupling. The dotted line 12 in Fig. 8 indicates this phase shift.
The attenuation circuit is shown. R ₁ is a variable resistor for phase shift adjustment, and the amount of phase shift is tan ^-1 ω _cR1 . _R3 is a variable resistor for attenuation, and the attenuation ratio is _R3 /( _R2 + _R3 ).
However, (1/ω _c )≪R ₂ and R ₃ ≪R ₄ . The wheel detection device shown in FIG. 8 requires a monitoring circuit using a window comparator to detect disconnection of the coupling circuit between the transmitting coil 4 and the second receiving coil 5b and failure of the phase shifter. The configuration is the same as the wheel detection device shown in FIG. 4 except for the circuit.

In addition, the above-mentioned (Fig. 3, Fig. 4, Fig. 8) train control
When using the wheel detection device shown in the figure), CT information and
There are cases where OT information and OT information are required almost simultaneously. In such a case, as shown in Figure 9, 1
transmitting coils 4 are connected to the first and second transmitting coils for CT information.
receiving coils 5a and 5b, and a first receiving coil for OT information.
It is also possible to share the coil between the second receiving coils 5'a and 5'b.

In addition, in order to perform balance adjustment of the first and second receiving coils 5a and 5b with high precision and efficiency, as shown in FIG.
A conceivable structure is that a ferrite core 13 whose insertion amount can be adjusted is housed in the receiving coil 5a), and a conductive plate 14 is disposed below the second receiving coil 5b.

That is, when the ferrite core 13 is inserted into the receiving coils 5a and 5b, the receiving level increases.
This increase value is several dB, and does not significantly improve the reception level, but after roughly adjusting the transmitting and receiving coils 4, 5a, and 5b to obtain a certain degree of differential output, the coil of the receiving coil 5a or 5b By moving the ferrite core 13 in the axial direction within the shaft, the differential output is finely adjusted.

FIG. 11 shows a sectional view of an embodiment of the receiving coil 5a or 5b (second receiving coil 5b in this embodiment) having a ferrite core 13. In this embodiment, the ferrite core 13 is embedded inside an exterior body 15 made of a non-metallic material, such as an insulating material such as synthetic resin. A screw 15a is cut into the outer periphery of the exterior body 15, and the shaft hole 1 of the winding frame 16 around which the receiving coil is wound is formed.
7 is screwed together so that it can be moved in the axial direction of the coil.

To adjust the differential output, the outer body 15 may be rotated within the shaft hole 17 to change the relative positional relationship between the ferrite core 13 and the receiving coil 5a or 5b.

Next, the function of the conductive plate 14 will be explained.
When obtaining a differential output between the first and second receiving coils 5a, 5b, the structure of both receiving coils 5a, 5b,
In other words, if the number of coil turns, coil diameter, etc. are the same, in principle, the first and second receiving coils 5
It is most convenient to arrange a and 5b symmetrically with respect to the transmitting coil 4 in order to obtain a differential output. That is, in FIG. 12, the distance from the transmitting coil 4 to the first receiving coil 5a
L ₁ and the second receiving coil 5b from the transmitting coil 4
This is when the distances L _{2 and 2} are equal.

However, it is desirable to set the distance L ₁ between the first receiving coil 5a and the transmitting coil 4 to a value that maximizes the detection sensitivity due to wheel entry. interval between
It is desirable to set L ₂ to a small value for the purpose of downsizing the structure, so in reality the interval L ₁
and L ₂ are not equal.

Now, leave the spacing L ₁ between the first receiving coil 5a and the transmitting coil 4 as is, and set the second receiving coil 5b to the required spacing L ₃ .
If it is brought close to the transmitting coil 4, the reception level of the second receiving coil 5b increases, resulting in a difference in induced voltage between the first and second receiving coils 5a and 5b, making it impossible to obtain a balanced output. in this case,
There is a method of lowering the reception level by reducing the number of coil turns of the second receiving coil 5b or by reducing its coil dimensions, but if the difference between the spacing L ₁ and L ₃ becomes large, this method alone will not work. , it becomes impossible to compensate.

Therefore, in the present invention, the second receiving coil 5
A conductive plate 14 is provided near b, so that the second
The induced voltage of the receiving coil 5b is reduced. In this case, by changing the distance between the conductive plate 14 and the second receiving coil 5b, the induced voltage of the second receiving coil 5b can be adjusted. As explained in detail above, the present invention disposes a transmitting coil and a receiving coil near a rail, and detects the wheel from disturbance of coupling caused between the transmitting coil and the receiving coil by the wheel running on the rail. In the wheel detection device, the receiving coil is comprised of a first receiving coil disposed sandwiching the receiving coil and the rail, and a second receiving coil disposed on a side of the rail where the transmitting coil is disposed. Since the differential output of the first receiving coil and the second receiving coil is used as the detection output, when installing the transmitting coil, simply install these coils at predetermined positions on both sides of the rail. This eliminates the need for adjusting the inclination of the coil axis. Therefore, the installation and handling of the receiving coil is easy and hassle-free.
This provides a highly reliable wheel detection device with stable characteristics.

[Brief explanation of the drawing]

FIG. 1 is a diagram explaining a conventional wheel detection device, FIG. 2 is a layout diagram of transmitting and receiving coils in the wheel detection device according to the present invention, FIG. 3 is an electric circuit diagram thereof, and FIG. 4 is another implementation. FIG. 5 is an electric circuit diagram of the window comparator, FIG. 6 is a diagram explaining its operation, FIG. 7 is a differential output characteristic diagram of the wheel detection device according to the present invention, and FIG.
The figure is also an electric circuit diagram in another embodiment, No. 9
10 is a diagram illustrating another embodiment of the receiving coil, FIG. 11 is a sectional view of a specific example of the receiving coil, and FIG. 12 is the receiving coil shown in FIG. 10. Each figure shows a diagram for explaining the operation of the coil. 1...Rail, 4...Transmission coil, 5a, 5'
a...first receiving coil, 5b, 5'b...second
Receiving coil, 13... Ferrite core, 14...
...Conductive plate.

Claims (1)

[Claims] 1. A transmitting coil and a receiving coil are disposed near a rail, and the wheels are prevented from being disrupted in coupling caused between the transmitting coil and the receiving coil by wheels running on the rail. In the wheel detection device, the receiving coil includes a first receiving coil disposed with the rail interposed between the receiving coil and the transmitting coil, and a second receiving coil disposed on the side where the transmitting coil is disposed. A wheel detection device characterized in that the detection output is obtained from a differential output between the first receiving coil and the second receiving coil. 2. The transmitting coil, the first receiving coil, and the second receiving coil are arranged such that their coil axes are perpendicular to a plane parallel to the tread surface of the rail. The wheel detection device according to item 1. 3. The wheel detection device according to claim 1, wherein the first receiving coil and the second receiving coil are connected in series. 4. A patent claim characterized in that the first receiving coil and the second receiving coil are connected in parallel, their differential output is monitored by a window comparator, and the output of the window comparator is used as a detection output. The wheel detection device according to item 1. 5. The wheel according to claim 1, 2, or 3, wherein the transmitting coil is shared between a plurality of sets of receiving coils including the first and second receiving coils. Detection device. 6. The wheel according to claim 1, 3 or 4, wherein the second receiving coil has a phase shift attenuation circuit and is inductively coupled to the transmitting coil. Detection device. 7. Claims 1, 2, 3, 4, 5, or 6, characterized in that the second receiving coil has a conductive plate below it. The wheel detection device described in section. 8. The wheel detection device according to claim 7, wherein the first receiving coil has a core whose insertion amount into the core can be variably adjusted.