JP2005045597A - Multiplexing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a failure rate smaller in a multiplexing device that uses a relay as a switch for switching a power signal. <P>SOLUTION: In this multiplexing device, a power switch circuit 11 for switching to output a standby power signal in place of a service power signal is provided with two relays 14 and 15, normally-closed contacts 14b and 15b of the two relays 14 and 15 are connected in series to form a series circuit 16, the normally-opened contacts 14a and 15a of the two relays 14 and 15 are connected in parallel to form a parallel circuit 17, a service power signal is inputted to one end of the series circuit 16, a standby power signal is inputted to one end of the parallel circuit 17, the other end of the series circuit 16 is connected to the other end of the parallel circuit 17, and a power signal is outputted from this connecting point. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention includes a first circuit for a standby system and a second circuit for a standby system. When the power signal from the first circuit of the normal system is abnormal, the second circuit of the standby system is substituted for the first circuit of the normal system. The present invention relates to a multiplexing device having a configuration for switching so as to output a power signal from a circuit.

In this type of multiplexing apparatus, if the switch for switching the power signal is configured by a semiconductor device, the switch is highly reliable, but if the power signal is high output, the high output power signal is applied to the semiconductor device for a long time. Therefore, the loss due to the on-resistance of the semiconductor device is a problem.
In addition, since the switching frequency of the switching switch in the multiplexing apparatus is very low, about once or twice a day, it is optimal to use a relay without on-resistance. Actually, the following Patent Documents 1 and 2 disclose a multiplexing device using a relay.
JP-A-7-107795 JP-A-6-259276

Now, the failure rate of a relay having a general configuration (that is, the probability that the normally closed contact cannot be turned off) is about 10 ⁻⁷ . This failure rate can be determined to be quite small when viewed as a single relay component, but considering that the failure rate of the entire multiplexing device system is determined by the failure rate of the relay, that is, the entire multiplexing device. The failure rate is not small enough. For this reason, it is required to further reduce the failure rate in a multiplexing device using a relay.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multiplexer that can further reduce the failure rate in a multiplexer that uses a relay as a switch for switching power signals. is there.

In the multiplexing device of the present invention, the power switching circuit for switching to output the standby power signal instead of the normal power signal is provided with two relays, and the normally closed contacts of these two relays are connected in series. A series circuit is formed, the normally open contacts of the two relays are connected in parallel to form a parallel circuit, the normal power signal is input to one end of the series circuit, and the standby is connected to one end of the parallel circuit. A power signal was input, the other end of the series circuit and the other end of the parallel circuit were connected, and the power signal was output from this connection point. According to this configuration, although it is a multiplexing device that uses a relay as a switch for switching power signals, it has two relays and is duplicated, and the normally closed contacts of these two relays are connected in series. Since a series circuit is formed, the failure rate of two normally closed contacts (series circuit) connected in series cannot be cut off is about (10 ^-7 ) ² = 10 ^-14, and the failure rate that cannot be cut off is greatly reduced. can do.

  Moreover, in the case of the said structure, it is also a preferable structure that the normally closed contact of the other end side of a series circuit and the normally open contact of the other end side of a parallel circuit are comprised by a transfer contact.

A first embodiment of the present invention will be described below with reference to FIGS. In the present embodiment, the present invention is applied to a transmission circuit connected to a loop antenna in a system that communicates between a loop antenna laid on a road and a coil antenna mounted on a vehicle.
FIG. 1 is a block diagram schematically showing the electrical configuration of this embodiment. As shown in FIG. 1, the output terminal d of the transmission circuit (multiplexer) 1 of this embodiment is connected to a loop antenna 2 laid on the road via a hybrid transformer 3. The transmission circuit 1 includes a regular transmission circuit (first circuit) 4, a standby transmission circuit (second circuit) 5, and a monitor switching circuit 6.

  The normal transmission circuit 4 has a function of outputting a normal power signal from the output terminal b, and includes a 48V power supply circuit 7, an input circuit 8, and a power amplifier circuit 9. In this case, a sine wave frequency-modulated with a frequency of, for example, 189 kHz is input to the input circuit 8. The power amplifying circuit 9 is configured to receive a sine wave from the input circuit 8, amplify the power here, and output a normal power signal from the output terminal b.

The standby transmission circuit 5 has a function of outputting a standby power signal from the output terminal c, and the electric circuit configuration and operation are the same as those of the regular transmission circuit 4. That is, the standby transmission circuit 5 includes a 48V power supply circuit 7, an input circuit 8, and a power amplification circuit 9.
The monitor switching circuit 6 receives the normal power signal from the normal transmission circuit 4 and the standby power signal from the standby transmission circuit 5, and outputs the normal power signal when the normal power signal is normal. 1 output terminal) d, and when the normal power signal is abnormal, the standby power signal is switched to be output from the output terminal (output terminal 1 of the transmission circuit 1) d instead of the normal power signal. Yes. The monitor switching circuit 6 has a function of outputting two monitor signals monitoring the normal power signal from the output terminals e1 and e2 and outputting a monitor signal monitoring the standby power signal from the output terminal f. .

  Output terminals e1, e2, and f of the monitor switching circuit 6 (transmission circuit 1) are connected to a control ECU (not shown), and each monitor signal is provided to the control ECU. The monitor switching circuit 6 is configured to be supplied with DC 48V power from the 48V power supply circuit 7 of the regular transmission circuit 4 and the standby transmission circuit 5 via the diode 10 respectively.

  Next, a specific configuration of the monitor switching circuit 6 will be described with reference to FIG. The monitor switching circuit 6 includes a power switching circuit 11, a first monitor circuit 12, a first 2 monitor circuit 12-2, and a second monitor circuit 13. The power switching circuit 11 includes two relays 14 and 15, and normally closed contacts (break contacts) 14 b and 15 b of the two relays 14 and 15 are connected in series to form a series circuit 16. A normally open contact (make contact) 14a, 15a of two relays 14, 15 is connected in parallel to form a parallel circuit 17.

  The one end 16a of the series circuit 16 is connected to the output terminal b of the normal transmission circuit 4, and the normal power signal is input to the one end 16a. Furthermore, one end 17a of the parallel circuit 17 is connected to the output terminal c of the standby transmission circuit 5, and a standby power signal is input to the one end 17a. Further, the other end 16b of the series circuit 16 and the other end 17b of the parallel circuit 17 are connected, and this connection point is connected to the output terminal d of the monitor switching circuit 6 so that a power signal is output from the connection point. It is configured.

Further, an excitation coil 14c and a transistor 20 of the relay 14 are connected in series between the DC 48V power line 18 and the ground line 19, and the excitation coil 15c and the transistor of the relay 15 are connected in parallel with the series circuit. 21 are connected in series.
On the other hand, the first monitor circuit 12, the first 2 monitor circuit 12-2, and the second monitor circuit 13 have the same electric circuit configuration, and are configured by a rectifier circuit and a comparison circuit, respectively. The 1 monitor circuit 12 will be specifically described with reference to FIG. The first monitor circuit 12 is configured by connecting a diode 22, resistors 23 to 28, a variable resistor 29, capacitors 30, 31, and a comparator 32 as shown in the figure. The first 2 monitor circuit 12-2 and the second monitor circuit 13 are configured in the same manner as the first monitor circuit 12.

  In this case, the input terminal 12a (the left end of the diode 22 in FIG. 2) of the first monitor circuit 12 and the input terminal 12-2a of the first 2 monitor circuit 12-2 are shared, and the output terminal of the regular transmission circuit 4 is used. Therefore, the common power signal is input to the input terminals 12a and 12-2a. Further, the input terminal 13a (left end of the diode 22 in FIG. 2) of the second monitor circuit 13 is connected to the output terminal c of the standby transmission circuit 5 so that the standby power signal is input to the input terminal 13a. ing.

  A terminal derived from the output of the comparator 32 of the first monitor circuit 12 is connected to the base of the transistor 20 of the power switching circuit 11 via a resistor 33. A Zed diode 35 is connected between the base and collector of the transistor 20, and a resistor 37 is connected between the base and emitter of the transistor 20. The terminal derived from the collector of the transistor 20 is used as the output terminal e1 of the monitor switching circuit 6.

  Similarly, a terminal derived from the output of the comparator 32 of the first two monitor circuit 12-2 is connected to the base of the transistor 21 of the power switching circuit 11 via a resistor 34. Note that a Zed diode 36 is connected between the base and collector of the transistor 21, and a resistor 38 is connected between the base and emitter of the transistor 21. The terminal derived from the collector of the transistor 21 is used as the output terminal e2 of the monitor switching circuit 6.

Further, the terminal derived from the output of the comparator 32 of the second monitor circuit 13 is used as the output terminal f of the monitor switching circuit 6. The output terminals e1 and e2 and the output terminal f are opposite in phase.
In the first monitor circuit 12, the normal power signal (sine wave signal) input to the input terminal 12a is rectified and converted to a DC voltage, and this DC voltage is compared with a set value (predetermined voltage value). When the voltage level of the DC voltage is equal to or higher than the set value (that is, when the normal power signal is normal), the comparator 32 becomes low level, the transistor 20 is turned off, and the monitor signal is output from the output terminal e1. A high level signal is output.

Similarly, also in the first 2 monitor circuit 12-2, when the normal power signal is normal, the comparator 32 becomes low level, the transistor 21 is turned off, and a high level signal is output as a monitor signal from the output terminal e2. It is comprised so that.
At this time (that is, when the normal power signal is normal), the two transistors 20 and 21 of the power switching circuit 11 are off, and the exciting coils 14c and 15c of the relays 14 and 15 are energized. Not.

In this case, the normally closed contacts 14b and 15b of the relays 14 and 15 are turned on, and the normally opened contacts 14a and 15a are turned off, so that the normal power signal is output from the output terminal d of the monitor switching circuit 6. ing.
On the other hand, the voltage of the DC voltage obtained by rectifying the common power signal (sine wave signal) input to the input terminals 12a and 12-2a of the first monitor circuit 12 and the first second monitor circuit 12-2. When the level becomes smaller than the set value (that is, when the common power signal becomes abnormal), each comparator 32 becomes high level, the transistors 20 and 21 are turned on, and a low level signal is output as a monitor signal from the output terminals e1 and e2. It is configured to be output.

At this time (that is, when the normal power signal becomes abnormal), the two transistors 20 and 21 of the power switching circuit 11 are turned on so that the exciting coils 14c and 15c of the relays 14 and 15 are energized. Will come to be.
Thereby, the normally closed contacts 14b and 15b of the relays 14 and 15 are turned off, and the normally open contacts 14a and 15a are turned on. As a result, the standby power signal is switched to be output from the output terminal d of the monitor switching circuit 6 instead of the normal power signal.

  In the second monitor circuit 13, the standby power signal (sine wave signal) input to the input terminal 13a is rectified and converted to a DC voltage, and this DC voltage and a set value (a predetermined voltage value) are converted. In comparison, when the voltage level of the DC voltage is equal to or higher than the set value (that is, when the standby power signal is normal), the comparator 32 becomes low level and a low level signal is output from the output terminal f as a monitor signal. It is the composition which becomes. The output terminal f has a signal level opposite to that of the output terminals e1 and e2.

In contrast, when the voltage level of the DC voltage obtained by rectifying the standby power signal (sine wave signal) input to the input terminal 13a of the second monitor circuit 13 is smaller than the set value (that is, the standby power signal). The comparator 32 is set to a high level and a high level signal is output as a monitor signal from the output terminal f.
The resistors 25 and capacitors 30 of the first monitor circuit 12, the first 2 monitor circuit 12-2, and the second monitor circuit 13 are time limit circuits for preventing the comparator 32 from going to a high level when the power is turned on. .

Here, the failure rate of the transmission circuit 1 configured as described above will be estimated. The failure rate is generally represented by the Fit number. 1 Fit is 10 ⁻⁹ / h, which is the number of failures per hour. The failure rates of the normal transmission circuit 4 and the standby transmission circuit 5 of the transmission circuit 1 are each within 10000 Fit. Accordingly, the probability of failure of the normal transmission circuit 4 and the standby transmission circuit 5 at the same time due to the dual system is as follows:
10 ⁴ * 10 ^-9 * 10 ⁴ * 10 ^-9 = 10 ^-10
Thus, it can be seen that the reliability is remarkably improved by 0.1 Fit.

However, if the failure rate of the monitor switching circuit 6 is large, the failure rate of the entire transmission circuit 1 also increases. Therefore, the present embodiment aims to improve the reliability of the monitor switching circuit 6.
That is, in the present embodiment, the first monitor circuit 12, the first two monitor circuit 12-2, and the power switching circuit 11 of the monitor switching circuit 6 are in a double system. The failure rate of the monitor switching circuit 6 excluding the relays 14 and 15 of the power switching circuit 11 is significantly smaller than that of the regular transmission circuit 4 and the standby transmission circuit 5, so the failure rate is about 100 Fit. ^Therefore , (10 ² * 10 ⁻⁹ ) ² = 10 ⁻⁵ Fit.

Next, the failure rate of the relays 14 and 15 will be described. Since the normally open contact 14a of the relay 14 and the normally open contact 15a of the relay 15 are connected in parallel, the failure rate that one of them is not closed from the open state is a multiplication of the respective failure rates. If the rate is 10 ⁻⁷ , it becomes 10 ⁻¹⁴ and 10 ⁻⁵ Fit.
On the other hand, if the normally closed contact 14b of the relay 14 and the normally closed contact 15b of the relay 15 are connected in parallel, the purpose of the two normally closed contacts 14b and 15b is to cut off the power signal from the normal transmission circuit 4. Therefore, the probability of failure (failure rate) is the logical sum of the probability of failure of each contact, and it can be seen that the reliability is not improved.

On the other hand, in the present embodiment, the normally closed contact 14b of the relay 14 and the normally closed contact 15b of the relay 15 are connected in series, so that the probability of failure (failure rate) is the logical product of the probability of failure of each contact. , Reliability is greatly improved.
In addition, the problem considered when the normally closed contacts 14b and 15b are connected in series is that, in the case of normal operation, when they must be closed, they are broken and opened. Is the magnitude of the failure rate. If this failure rate is large, the two contact points 14b and 15b are connected in series, so that the failure rate is doubled, which is a problem. However, according to the relay handbook (Morikita Publishing 1992), the failure rate at which the normally closed contact opens when the coil is not energized is much smaller than the failure rate when the coil is energized.

Moreover, even if the failure causes the normally closed contact 14b or the normally closed contact 15b to open from the closed state, the normally open contact 14a or the normally open contact 14b is closed and the normal transmission circuit 4 switches to the standby transmission circuit 5. Therefore, there is no problem. In addition, according to the relay handbok, the failure rate at which the normally closed contact is defective when the coil is not energized is remarkably small.
In the duplex system, as described above, the failure rate at which the normal transmission circuit 4 and the standby transmission circuit 5 simultaneously fail becomes the product of the failure rates of the respective circuits, and the failure rate of the entire system is significantly reduced. Therefore, it is necessary to always monitor the regular transmission circuit 4 and the standby transmission circuit 5 through the first monitor circuit 12, the first 2 monitor circuit 12-2, and the second monitor circuit 13 by the control ECU. . If a failure is detected, it is necessary to repair it immediately.

The monitor switching circuit 6 needs to be inspected once a month or once every six months. This is because the first monitor circuit 12, the first 2 monitor circuit 12-2, the second monitor circuit 13, and the contacts 14a, 14b, 15a, 15b are outputting normal signals even if they are out of order. Because there is.
In this embodiment having such a configuration, the power switching circuit 11 that switches to output a standby power signal instead of the normal power signal is provided with two relays 14 and 15, and the two relays 14 and 15 are provided. The normally closed contacts 14b and 15b are connected in series to form a series circuit 16, and the normally open contacts 14a and 15a of the two relays 14 and 15 are connected in parallel to form a parallel circuit 17. A normal power signal is input to one end of the circuit, a standby power signal is input to one end of the parallel circuit 17, the other end of the series circuit 16 and the other end of the parallel circuit 17 are connected, and a power signal is output from this connection point. Configured.

According to this configuration, although it is a multiplexing device using a relay as a switch for switching electric power signals, two relays are provided and duplexed, and normally closed contacts 14b, 15b of these two relays 14, 15 are used. Are connected in series to form the series circuit 16, so the failure rate of the two normally closed contacts 14 b and 15 b (series circuit 16) connected in series is about (10 ⁻⁷ ) ² = 10 ^−14. The failure rate can be greatly reduced as compared with a single relay configuration.

FIG. 4 shows a second embodiment of the present invention. The same parts as those in the first embodiment are denoted by the same reference numerals. In the second embodiment, the normally closed contact 14b on the other end side of the series circuit 16 in the monitor switching circuit 6 and the normally open contact 14a on the other end side of the parallel circuit 17 are constituted by transfer contacts. That is, the relay 14 is constituted by a transfer contact type relay.
The configuration of the second embodiment other than that described above is the same as the configuration of the first embodiment. Therefore, in the second embodiment, substantially the same operational effects as in the first embodiment can be obtained.

  In the second embodiment, the relay 14 is a transfer contact type relay. However, instead of this, the other relay 15 may be a transfer contact type relay. In this configuration, the movable contact (common contact) of the transfer contact of the relay 15 is connected to the output terminal d, the output terminal b of the regular transmission circuit 4 is connected to the normally closed contact 14b of the relay 14, and the relay 14 is normally opened. What is necessary is just to comprise so that the output terminal c of the standby transmission circuit 5 may be connected to the contact 14a.

  In the first and second embodiments, the transistor 20 is turned on / off by the output signal of the first monitor circuit 12, and the transistor 21 is turned on / off by the output signal of the first second monitor circuit 12-2. Thus, the relays 14 and 15 are cut off. However, when the failure rate of the monitor circuit is smaller than the failure rate of the power switching circuit, two relays are provided depending on the output signal output from the first monitor circuit 12. The transistors 20 and 21 may be turned on and off to disconnect the relays 14 and 15. Even if comprised in this way, the same effect can be acquired.

1 is an electric circuit diagram of a transmission circuit according to a first embodiment of the present invention. Electric circuit diagram of monitor switching circuit Electrical circuit diagram of first monitor circuit (first two monitor circuit, second monitor circuit) FIG. 2 equivalent view showing a second embodiment of the present invention

Explanation of symbols

In the drawings, 1 is a transmission circuit (multiplexer), 2 is a loop antenna, 3 is a hybrid transformer, 4 is a regular transmission circuit (first circuit), 5 is a standby transmission circuit (second circuit), and 6 is a monitor switching circuit. , 8 is an input circuit, 9 is a power amplifier circuit, 11 is a power switching circuit, 12 is a first monitor circuit, 12-2 is a first 2 monitor circuit, 13 is a second monitor circuit, 14 and 15 are relays, 16 Is a series circuit, 17 is a parallel circuit, 18 is a power supply line, 19 is a ground line, 20 and 21 are transistors, and 32 is a comparator.

Claims (2)

A first circuit that outputs a normal power signal, a second circuit that outputs a standby power signal, and a power switch that switches to output the standby power signal instead of the normal power signal when the normal power signal is abnormal A multiplexing device comprising a circuit,
The power switching circuit includes two relays, the normally closed contacts of these two relays are connected in series to form a series circuit, and the normally open contacts of the two relays are connected in parallel. Forming a circuit, inputting the common power signal to one end of the series circuit, inputting the standby power signal to one end of the parallel circuit, connecting the other end of the series circuit and the other end of the parallel circuit; A multiplexing apparatus configured to output a power signal from the connection point. 2. The multiplexing apparatus according to claim 1, wherein the normally closed contact on the other end side of the series circuit and the normally open contact on the other end side of the parallel circuit are constituted by transfer contacts.

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