JPS6025751B2 - Vehicle detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle detection device used in a railway signal or traffic signal control device, and in particular, to detect electromagnetic interference between the transmitting coil and the receiving coil caused by a vehicle entering the installation area of the transmitting coil and the receiving coil. The present invention relates to a device that detects a vehicle by utilizing a change in the degree of coupling, particularly a change due to electromagnetic induction effect (voltage induced in a receiving coil increases as the vehicle approaches).

A transmitter coil and a receiver coil are installed on a railway or road a predetermined distance apart, and an AC signal of V,sin of t is supplied to the transmitter coil, and the V2sin received by the receiver coil is
The AC signal at (t+◇) is processed by the receiving circuit, and the reception level increases when a train or car enters the installation area of both coils (the so-called detection area, such as between the coils, above the coils, etc.) An example of a device that detects a vehicle by utilizing this fact is Japanese Patent Publication No. 1974-1974 (Vehicle Detector), which was written by one of the applicants of the present invention.

This detection device uses a transmitter circuit and a receiver circuit, but their characteristics vary depending on the temperature, and the variation can be 10% or more, so changes in the reception level due to the approach of a vehicle are If the variation is small, the variation may offset the variation due to the entry of a vehicle into the installation area, and conversely, the variation may erroneously output detection information indicating the presence of a vehicle. Therefore, in order to detect a vehicle using an electronic circuit by utilizing changes in the degree of electromagnetic coupling due to the vehicle entering the installation area of both coils, it is essential to reduce interference caused by fluctuations in temperature and power input. Yes, in the follow-up, the signal caused by the vehicle entering the installation area is differentially extracted using an attenuation phase shift circuit, transformer, balance coil, etc., and the extracted signal (differential output) is input to the level detector. By doing so, the effects of the above-mentioned obstacles were reduced.

In this case, in a fail-safe detection device, a fail-safe window comparator is used as a level detector, and the differential output is always within the window of the window comparator, and the differential output changes as the vehicle approaches. When the vehicle detection output is output when the differential output is out of the window range of the window comparator (this information is called CT information), and when the differential output is always outside the window range of the window comparator (low level) In this case, a vehicle detection output is output when the differential output falls within the range of the window of the window comparator due to changes in the differential output due to the approach of the vehicle (this information is called OT information). There is.

Here, the function of the window comparator is to set two threshold levels (E,,E2) for the differential output.
(E.<Town 2), and this threshold level E,
, E2, the window comparator oscillates and produces an output, and the differential output is below the threshold level E, or below the threshold level E2.
In this case, the window comparator has a characteristic of not oscillating and producing no output, and the input range E, 1-E2 in which the window comparator oscillates and produces an output is called a window.
The detection device of the present invention uses the above-mentioned O as information for vehicle detection.
The present invention relates to a detection device for obtaining T information, especially when changes in differential output due to vehicle entry vary significantly depending on the vehicle type. In the above-mentioned detection device that obtains OT information, the reed output is always outside the window of the window comparator (at a level lower than the low-level threshold), and changes in the signal due to the approach of a vehicle The window comparator generates a vehicle detection output when the differential output comes within the range of the window of the window comparator, but in this case, the range of the window of the window comparator changes the differential output as the vehicle approaches. The threshold level of vehicle detection, that is, the threshold level of one of the windows E,
At the same time, if a failure occurs in the differential circuit that generates a differential output, the condition is that the differential output must exceed (with a larger change) the change in the output due to the vehicle's approach. The differential output due to this failure extends beyond the other threshold level E2 that provides the window of the window comparator, so due to the failure of the differential circuit, the window comparator does not generate output information equivalent to vehicle detection.
In other words, the configuration is such that no output signal is generated in the window comparator.

As mentioned above, when obtaining OT information by using the differential output as the input of a window comparator, a failure occurs in the differential circuit that provides the differential output, and "the difference between the two input signals that provide the differential output" The condition is that the change in the differential output due to the vehicle's approach is smaller than the differential output that occurs when one of them disappears, and if the change in the differential output due to the vehicle's approach is If the change is greater than the change in differential output due to a failure, the output of the window comparator has the drawback that no output information for vehicle detection is generated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a vehicle detection device that can generate vehicle detection output information even when a change in differential output due to a vehicle's approach is larger than a change in differential output due to a failure of an inset circuit. .

Hereinafter, the present invention will be explained in detail based on embodiments shown in the drawings.

In FIG. 1, 1 is a transmitting coil, 2 and 3 are first and second receiving coils installed at a predetermined distance from the transmitting coil, and 4 is a first receiving coil installed near the transmitting coil 1. The balance coil 5 is a second balance coil provided near the first receiving coil 2.

The transmission coil 1 has an AC transmission output V of V, sin t.
a is input from the transmitting circuit 6, thereby the receiving coil 2
, 3 are directly guided to receive inputs Vb, Vc. The balance coils 4 and 5 are coupled in opposite phase to the coupling between the coils 1 and 2, that is, the differential input Vd induced to the reception coil 2 via the balance coils 4 and 5 is connected to the transmission coil 1. They are connected to each other so as to be operative with respect to the receiving input Vb directly induced in the receiving coil 2, so that the receiving coil 2 has Vb-Vd with respect to the transmitting output Va.
signal is received.

To connect balance coils 4 and 5 in this way, for example, when the magnetic fields of coils 1 and 2 are in the directions of arrows 1' and 2', the direction of the magnetic field of coil 5 is in the direction of arrow 5'. Just connect it like this. The receiving coils 2 and 3 are installed at the same point with respect to the transmitting coil 1 at equal intervals, and the second balance coil 5 is provided so that its magnetic field does not affect the second receiving coil 3.

To provide each coil in this way, for example, as shown in FIG. Further, the second balance coil 5 can be provided within the loop of the first receiving coil 2 and outside the loop of the second receiving coil 3. 7 is a first receiving circuit that tests the presence or absence of a vehicle based on the received signal Vb-Vd of the first receiving coil 2; 8 is a first receiving circuit that tests the presence or absence of a vehicle based on the received signal Vc of the second receiving coil 3; The second receiving circuit 9 is an OR circuit that outputs an OR signal of the vehicle presence detection signals outputted from both receiving circuits 7 and 8 as detection information indicating the presence of a vehicle.

Each receiving circuit 7, 8 includes an amplifier 7a, which amplifies the input signal from the corresponding receiving coil, for example, AC, and outputs DC.
8a, and window comparators 7b and 8b for verifying the levels of the output signals of the amplifiers 7a and 8a. Since the circuit for amplifying and rectifying AC is already known, its explanation will be omitted. Hereinafter, the window settings of the window comparator will be explained in detail with reference to FIG. In FIG. 3, the vertical axis indicates the input voltage of the receiving circuits 7 and 8, and the vertical axis indicates the elapsed time t accompanying the passage of the vehicle.

In FIG. 3, E. , E2, and E3 are also input conversion values that operate the window comparator. E,,E
2 indicates that the two threshold levels E3 of the window comparator 7b are the lower limits of the threshold levels of the window comparator 8b. The voltage eV2 is the reception level Vc of the reception circuit 8 when no vehicle approaches, the voltage pole V is the reception level of the reception circuit 7, and the voltage pole V. is the difference eV. between the raw received voltage yb of the receiving coil 2, which is not affected by the differential effect, and the differential input Vd, which provides a differential effect, when no vehicle enters the vehicle. (=Vb-Vd).

Furthermore, P and P' are the reception levels of each receiving coil when a vehicle with a large amount of change approaches, and q and q' are the reception levels of each receiving coil when a vehicle with a large amount of change approaches. . The window comparators 7b and 8b are known circuits using asymmetric error circuits, and the window of the window comparator 7b is set in the range of the input conversion value voltages E, , E2 of the output of the receiving circuit 7 in FIG. The window of the window comparator 8b is set to a sufficiently large window range that is equal to or larger than the input conversion value voltage E3 of the output of the receiving circuit 8.

The voltage E, is the differential output Vb-Vd (=e
The voltage E2 is set to a value slightly higher than V, ), and the voltage E2 is a value at which the output of the first receiving circuit 7 disappears when the balance coils 4 and 5 are disconnected or disconnected. Voltage E3 is less than or equal to the change that occurs in coil 3 corresponding to the change E2 - eV, which occurs in coil 2 when the vehicle enters between coils 1, 2, and 3, that is, eV2・(E2−eV,)/Vb. , and is set to a value higher than the level eV2 of the reception signal Vc of the second reception coil 3 when there is no vehicle. is set so that vehicle detection is performed seamlessly. Note that no change occurs in the differential input Vd due to vehicle entry. Therefore, for example, E, 1 eV, is Vb
The rate of change in Vd and the rate of change in Vc are approximately equal if the electromagnetic relationship is the same between coils 1 and 2 and between coils 1 and 3 (if the number of turns of the coils is different, they will be completely different). body values will vary). That is, in FIG. 3, on the time axis t, if a vehicle passes in the opposite direction from t, the input voltage Vb-Vd of the receiving circuit 7 changes as q, and the receiving circuit 7 changes as shown in FIG. 7, t2,
The vehicle is detected during t3, and the input voltage Vc of the receiving circuit 8
changes like q' and is not detected by the receiving circuit 8.
For a vehicle with a large variation, the input voltage Vb-Vd of the receiving circuit 7 changes as P, and the receiving circuit 7 changes as (t, ~
t,') (t'-t4), the detection output is output. ′
No detection output is generated during the period from ~t4'. At this time, the receiving circuit 8
The input voltage Vc changes as P', and the receiving circuit 8 produces a detection output between t5 and L, and t,'>t5>, t4
Since it is set to >t6>shi', the receiving circuit 7 or 8 can provide a continuous detection output for a vehicle with a large amount of change. In this device, V,sin is applied to the transmitting coil.
When the AC transmission output Va of t is input, the reception input Vb is directly induced from the transmission coil 1 to the reception coil 2, and the differential input Vd is induced via the balance coils 4 and 5. , differential output Vb to the first receiving circuit 7
-Vd is input, and since the receiving input Vc is induced in the receiving coil 3, the signal Vc is directly input to the second receiving circuit 8.

If there is no vehicle now, the level of the differential output Vb-Vd will be e.
Since the level of the signal Vc is eV2, neither of the receiving circuits 7 and 8 outputs a detection signal, and the OR circuit 9 does not output detection information. However, when a vehicle with a large change in electromagnetic coupling enters the vehicle, the reception levels of the receiving coils 2 and 3 become P and P' as shown in FIG. 3.

As a result, the first receiving circuit 7 has a period T,, (=t,
~L'), L, (=shi'~t4) outputs a detection signal indicating the presence of a vehicle, and the second receiving circuit 8 outputs a detection signal indicating the presence of a vehicle by the amount of time it takes to detect the presence of a vehicle. A vehicle presence detection signal is output for a period T3 within the range of , and as a result, vehicle presence detection information is output from the OR circuit 9 from time t to t4. In addition, when a vehicle with a small change in electromagnetic coupling enters, each receiving coil 2, 3
The reception levels of q and q' shown in FIG.

As a result, the first receiving circuit 7 outputs a vehicle presence detection signal at T4 (=ra~t3) since the level of the input signal falls within the range of the window of the window comparator 7b. In the circuit 8, the level of the input signal does not reach the window range of the window comparator 8b. Therefore, in this case, the OR circuit 9 outputs vehicle presence detection information from time t2 to time t3. On the other hand, balance coils 4 and 5
If the differential circuit is disconnected or disconnected, that is, if a failure occurs in the differential circuit, the input to the receiving circuit 7 will exceed the threshold level E2, so no output will be generated, and at the same time,
Since the input to the receiving circuit 8 remains at eV2 (does not exceed E3), no output is produced.

In other words, even if the change in the differential output due to the approach of a vehicle is greater than the change in the differential output due to a failure in the differential circuit, the output voltage for vehicle detection can be generated, and at the same time, if a failure occurs in the differential circuit, It is possible to generate a fail-safe detection output (OT information) in which no output voltage is generated. FIG. 4 is a diagram showing an embodiment of the window comparators 7b and 8b used in the above-mentioned receiving circuits 7 and 8, which do not generate an output due to a circuit failure.

In this example, the window comparator is composed of an oscillation circuit using three transistors 11, 12, 13, and the resistors 14, 15, 17, 20, 21 are connected to the transistor 11.
, 12, and 13, one battery, and a power source for the transistor 12.

The base of each transistor is directly connected to the output of the previous transistor. That is, the output of the transistor 13 is supplied to the base of the transistor 11 via a resistor 16 with a division ratio of collector resistors 14 and 15, and the output of the transistor 11 is supplied to the base of the transistor 12 via the power supply 10 through resistors 18 and 19. The output of the transistor 12 is divided by the resistors 20 and 21 and combined with the base of the transistor 13. This window comparator detects that when a certain input voltage is applied to the input terminal, the transistor 11
→Transistor 12 →Transistor 13 →Transistor 11 constitutes a feedback oscillator to which the output of each transistor is supplied in the order. The input voltage range in which this window comparator can oscillate is the voltage of the power supply 10 as Vo, and the resistor as 1.
The resistance values of 4, 15, 17, 18, and 19 are R, 4, and R, respectively.
,5,R,7,R,9,The voltage level of the input signal is V,
, the lower limit of the input voltage V for oscillation is e, and the upper limit is e2.
When , approximately el・RI9×R170R180R
I9)=V.

E}e2・R5/(R140R15);V.
...(2}. Here, the space between e and e2 is the window of the window comparator. If the input voltage V, is lower than the lower limit e, the transistors 12 and 1
Since transistor 11 remains off while transistor 3 is on, it does not oscillate.

When the input voltage V, becomes larger than the lower limit e, transistors 12 and 13 are turned off, so transistor 1
1 is turned on. When transistor 11 turns on,
Transistors 12 and 13 are turned off, and transistor 11 is turned off.
is in the off state. When transistor 11 is turned off, transistors 12 and 13 are turned on, so that the window comparator continues to oscillate.
Further, when the input voltage V, exceeds the upper limit e2, even if the transistor 13 is turned on, the transistor 11 will not be turned off, so that the oscillation circuit will be unable to oscillate. As is clear from conditional expressions 1 and 2, the lower limit e and upper limit e2 of the input voltage V at which the window comparator oscillates depend on the values of the resistors 14, 15, 17, 18, and 19. By selecting these resistance values appropriately,
The oscillation start voltage can be set freely.

In addition, since the signal of the amplifier whose output becomes zero due to a failure is AC, an AC amplifier can be used.For the OR circuit, the outputs of the window comparators 7b and 8b mentioned above can be rectified and the outputs can be connected directly. Since this is a general fail-safe technology, its explanation will be omitted. FIG. 5 is a diagram showing another embodiment of the vehicle detection device, and this device uses transformers 22 and 23 to connect the reception input Vb and the differential input Vd instead of providing a balance coil and a second reception coil. Differential output Vb-V
d and a reception input Vc that does not include the differential input Vd.

The transformer 22 has two negative side coils 24 and 25, one of which is connected to the receiving coil 2 and supplied with the receiving input Vb, and the other is connected in parallel with the transmitting coil 1 and provides the transmitting output Va.
is supplied.

The coils 24 and 25 are arranged as indicated by arrows 24' and 25'.
In other words, the receiving input Vb is induced in the secondary coil of the transformer 22 by the coil 24, and the differential input Vd is transferred by the coil 25 so that the magnetic field is in the opposite direction. The receiver circuit 7 is configured to receive a reed output of Vb-Vd. transformer 23
The primary coil is connected in parallel to the primary coil 24 of the transformer 22, and the secondary coil is connected to the second receiving circuit 8.

The reception input Vc transferred to the secondary coil of the transformer 23 is substantially the same as the reception input Vb. This vehicle detection device has the following features: except that a differential output of Vb-Vd is generated in the secondary coil of the transformer 22, and a reception input Vc that does not include the differential input Vd is generated in the secondary coil of the transformer 23. It operates in the same way as the vehicle detection device shown in FIG.

Therefore, both vehicles with large and small changes in electromagnetic coupling can be detected. In FIG. 5, the coil 25, this lead cable and the coil 2
4 and this lead cable, no output voltage is generated in the receiving circuit 7 or the receiving circuit 8 as in the case shown in Fig. 2. It is possible to detect small vehicles (when the signal change due to vehicle entry is larger than the change in differential output due to differential output) and small vehicles (when the signal due to vehicle entry is smaller than the change in differential output due to differential circuit failure). It is also possible to detect when a failure occurs. Note that the configuration in Figure 2 consists of coils 1 and 2.
, 1 and 4, and 2 and 5 are spatial connections, and the physical connections are the same.

In comparison with FIG. 2, in FIG. 5, only the coupling between coils 1 and 2 is through the air (spatial coupling). The differential output Vb-Vd (=eV,) is generated as the output of the transformer 22, and of the two inputs that provide the differential output, the coil 2
4 is given a spatially coupled input, and the coil 25 is given an electrically coupled input from the coil 1, and the input paths that provide the differential output are not physically unified, so generally,
The configuration shown in FIG. 2 has the advantage of being less susceptible to differential output fluctuations (called drift) caused by seasonal changes, temperature changes, etc. As described above, the present invention not only verifies the presence or absence of a vehicle in the first receiving circuit based on the differential output from the differential input and the receiving input Vb, but also eliminates the differential input. Based on the received input, the presence or absence of a vehicle is verified by the second receiving circuit, and the OR signal of the output signals of both receiving circuits is output. By verifying the presence or absence of a vehicle with the first receiving circuit and verifying the presence or absence of a vehicle with a large change with the second receiving circuit, it is possible to detect a vehicle in a fail-safe manner.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing an example of an electric circuit of a vehicle detection device, Fig. 2 is an explanatory diagram of the arrangement rows of coils, Fig. 3 is an explanatory diagram of electric signals, and Fig. 4 is a circuit showing an example of a window comparator. 5 are block diagrams of electric circuits showing other examples. 1: Transmission coil, 2, 3: Receiving coil, 4, 5: Balance coil, 7, 8: Receiving circuit, 9: OR circuit, 22, 2
3: Trance. Figure 1 Figure 2 Figure 5 Figure 3 Figure 4

Claims (1)

[Claims] 1 In a vehicle detection device that installs a transmitter coil and a receiver coil apart and detects a vehicle by using changes in the degree of electromagnetic coupling between the two coils due to the vehicle entering the installation area of both coils, a differential A first receiving circuit 7 that verifies the presence or absence of a vehicle based on the differential output Vb-Vd from the differential input Vd and the receiving input Vb, and at the same time outputs no output due to a failure of the operating circuit; A second receiving circuit 8 that verifies the presence or absence of a vehicle based on the received input Vc that does not contain the signal, and an OR circuit 9 that outputs a logical sum signal of the output signals of both receiving circuits 7 and 8.
This makes it possible to detect both vehicles that give a signal greater than the signal due to a differential circuit failure as well as vehicles that give a small change less than the signal due to a differential circuit failure, and a detection output when the differential circuit fails. A vehicle detection device characterized in that it does not generate.