JPH047026Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial field of application] The invention is used in railway vehicles, for example, to electrically monitor whether the air pressure in the source air reservoir is equal to or higher than the reference pressure, and to monitor the air pressure when the pressure is lower than the reference pressure. This invention relates to an electric air pressure switch for railway vehicles that activates an emergency brake.

[Conventional technology]

As a conventional example of this type of electric pressure switch,
In Figure 7 of Special Publication No. 59-24604, the symbols VISG,
There are those indicated by OPA1, ACSG, OPA4,
An air pressure switch based on this is shown in FIG. 3 and will be described below.

In Figure 3, 1 is a pneumatic converter, 2 is a differential amplifier, 3 is a comparator, 4 is a switching element, EB
is the emergency brake command line.

The pneumatic converter 1 is connected to a DC power supply +V, 0, and consists of a bridge circuit incorporating a strain gauge, and converts the air pressure of a source air reservoir (not shown) into a potential difference between its output ends 1a and 1b. Output.

The differential amplifier 2 amplifies the potential difference and transmits it to the comparator 3 as an electric signal Ei corresponding to the air pressure.

Comparator 3 compares input signal Ei with a reference value +V1 corresponding to reference air pressure, and when Ei<+V1, sets its output Eo to a high level and demagnetizes relay RY.
Turn off contact RYa that constitutes switching element 4
When Ei≧V1, the output Eo is set to a low level, the relay RY is energized, and the contact RYa is turned on.

In railway vehicles, the source air reservoir is used as an air source for air brake devices and automatic door opening/closing devices, and if the air pressure is below the standard pressure, it will cause serious problems in vehicle operation. , the monitoring of the air pressure is given great importance.

In other words, under normal conditions when the air pressure in the source air reservoir is higher than the reference pressure, Ei
≧V1, the contact RYa is ON, and the emergency solenoid valve (not shown) connected to the emergency brake command line EB is loosening and operating.

If the piping under the vehicle floor is damaged and the air pressure in the source air reservoir drops below the standard pressure,
In the above air pressure switch, Ei<Vi, and the contact RYa turns OFF, so the emergency solenoid valve operates the brake, and the emergency brake is applied to the vehicle.

Note that the above-mentioned air pressure switch is sometimes used in a railway vehicle to control an air compressor or to monitor the operating pressure of each component of an air brake system.

[Problem that the invention attempts to solve]

However, since the above-mentioned conventional air pressure switch is a DC type, if any of its components, for example 3, fails, it is not determined whether the switching element 4 is turned ON or OFF depending on the content of the failure, and it is not a fail-safe switch. There is a problem of lack of reliability in terms of

For example, when the switching element 4 is placed on the emergency brake command line EB as described above,
If switching element 4 remains ON due to a failure somewhere, even if the air pressure in the source air reservoir drops below the standard pressure, the emergency brake will not operate and the driver will This is extremely dangerous because you will only realize that the brakes are weak after you apply the brakes.

[Means for solving problems]

Therefore, the technical means of the present invention to solve the above problem consists of a pneumatic converter that outputs an electrical signal according to air pressure, a comparator that inputs this electrical signal and compares it with a reference value, and a comparator that inputs this electrical signal and compares it with a reference value. a switching element that operates based on the output, an oscillator is connected to the pneumatic converter, and the output of the pneumatic converter is used as an alternating current signal;
The comparator is configured to output an alternating current signal when the reference value is within the amplitude of the alternating current signal, and output a direct current signal when the reference value deviates from the amplitude of the alternating current signal, A capacitor for blocking a DC signal is connected to the output side of the comparator, and the switching element is in a first state when a signal is supplied via the capacitor and is in a second state when a signal is not supplied. It is characterized by the fact that

[Effect]

According to the above means, the reference value of the comparator is set within the amplitude of the AC signal output from the pneumatic converter when the air pressure is equal to or higher than the reference pressure value, and when the air pressure is less than the reference pressure. By setting it so that it deviates from the amplitude of the AC signal, the output of this comparator is
When the air pressure is above the reference value, it becomes an AC signal, and when it is less than the reference pressure, it becomes a DC signal. A capacitor that blocks direct current is connected to the output side of this comparator, so when the air pressure is higher than the reference pressure, an alternating current signal is supplied to the switching element via the capacitor, and the switching element returns to the first state. Become. However, when the air pressure is less than the reference pressure, the DC signal of the comparator is blocked by the capacitor,
The switching element is not supplied, and the switching element is in the second state.

If any one of the oscillator, the pneumatic converter, and the comparator fails, for example, if the oscillator or the pneumatic converter fails, the comparator is supplied with a DC signal instead of an AC signal. Therefore, the output of the comparator also becomes DC. Furthermore, if the comparator fails, the output becomes DC even if an AC signal is input. Even if a fail occurs in either of these, the output of the comparator becomes DC,
Since this is blocked by the capacitor and is not supplied to the switching element, the switching element is in the second state, providing fail-safety.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the schematic electric circuit shown in FIG. 1 and the operation diagrams of each part shown in FIGS. 2 and 4.

In FIG. 1, 10 is an oscillator, 11 is a pneumatic converter, 12 is a differential amplifier, 13 is a comparator, 4 is a switching element, and EB is an emergency brake command line.

The oscillator 10 is connected between the DC power supply +V and 0, and the unijunction transistor UJT
The oscillation circuit generates oscillation using a flip-flop circuit FF, which keeps the amplitude constant and the duty ratio
Shape the waveform into a 50% square wave and apply it to the transistor.
It is amplified at TR1. The waveforms of the portions indicated by symbols A, B, C, and D of the oscillator 10 in FIG. 1 are shown in A, B, C, and D in FIG. 2, respectively.

The pneumatic converter 11 is equipped with a strain gauge like the conventional one, but its power source is the output D (alternating current) of the oscillator 10, and it is driven in a choppy manner, depending on the air pressure in the source air reservoir. As a result, the amplitude of the AC output E changes. This is shown in Figure 2E.
The first half of FIG. E shows the case where the air pressure in the source air reservoir is lower than the reference pressure, and the second half shows the case where the air pressure in the source air reservoir is higher than the reference pressure.

The differential amplifier 12 has an operational amplifier OP1, amplifies the AC output E of the air converter 11, and transmits it to the comparator 13 as an output F. This output F is the second
It is shown in Figure F by the solid line. Note that a capacitor C1 is provided on the output side of the operational amplifier OP1 of the differential amplifier 12 to cut off the DC component.

The comparator 13 has an operational amplifier OP2, and compares its input (output of the differential amplifier 12) F with a reference value +V1 (shown by a dotted line in FIG. 2F) corresponding to the reference pressure of the source air reservoir. And when F≧+V1,
When the output G becomes high level and F<+V1,
Output G becomes low level. Therefore, as shown in the second half of FIG. 2F, if the reference value +V1 is within the amplitude of the AC output F of the differential amplifier 12 (if the pressure of the source air reservoir is higher than the reference pressure), then As shown in the second half of , the output G of the comparator 13 becomes high level in the positive half cycle of the AC output F of the differential amplifier 12,
During the negative half cycle of the AC output F of the differential amplifier 12, the output G of the comparator 13 becomes a low level. As a result, the output G of the comparator 13 becomes an AC signal when the pressure of the source air reservoir is equal to or higher than the reference pressure. In addition, as shown in the first half of the figure F, if there is no reference value +V1 within the amplitude of the AC output F of the differential amplifier 12 (if the pressure of the source air reservoir is less than the reference pressure), then As shown in FIG. 2, the output G of the comparator 13 maintains a low level and becomes a DC signal.

The output G of this comparator 13 is the transistor TR
This transistor TR2 is turned ON when the output G of the comparator 13 is at a high level, its output H is at a low level, and is turned OFF when the output G of the comparator 13 is at a low level, and its output H is Becomes a high level. Therefore, when the output G of the comparator 13 is an AC signal, the transistor
The output H of TR2 repeats a low level and a high level, but when the output G of the comparator 13 is a DC signal that maintains a low level, the transistor TR2 maintains a high level state.

The output side of this transistor TR2 is connected to the input side of a full-wave rectifier RE via a capacitor C2, and the output side of this full-wave rectifier RE is connected to a relay RY.
is connected. Therefore, capacitor C2 is
Since the output H of the transistor TR2 is charged when it is at a high level and discharged when it is at a low level, the potential I at the input side of the full-wave rectifier RE changes in accordance with this charging and discharging.

For example, when the output G of the comparator 13 is an AC signal and the transistor TR2 is repeatedly turned on and off, the potential I on the input side of the full-wave rectifier RE is
As shown in the second half of Figure I, the positive and negative changes are repeated in response to charging and discharging, and this is full-wave rectified by the full-wave rectifier RE, and the relay on the output side of the full-wave rectifier RE
RY is supplied with a positive full-wave voltage as shown in the second half of FIG. 2J, which causes the contact, which is the switching element 4, to
RYa turns ON.

Further, when the output G of the comparator 13 is at a low level, the output H of the transistor TR2 is at a high level, thereby completely charging the capacitor C2. As a result, the potential I on the input side of the full-wave rectifier RE becomes 0 as shown in the first half of Fig. 2 I, the voltage J across the relay RY becomes 0 as shown in the first half of Fig. is turned OFF as shown in the first half of FIG.

Now, assuming that the air pressure in the source air reservoir is normal when it is higher than the reference pressure, the input F in the comparator 13 is an AC signal, and in its positive half cycle, F≧+V1, and as shown in FIG. As shown in the second half of 4, the output G of the comparator 13 becomes an alternating current signal, and in response to this, the transistor TR2 turns on and off.
OFF is repeated, capacitor C2 is repeatedly charged and discharged, this is full-wave rectified by full-wave rectifier RE, relay RY is energized, contact RYa is set to 0N, and the emergency brake is released (relaxed).

On the other hand, if the air pressure in the source air reservoir drops below the standard pressure due to an abnormality such as pipe damage, the comparator 13
The input signal F of is an alternating current signal, but in its positive half cycle F<+V1, and as shown in the first half of FIG. 2F to FIG. is turned OFF, capacitor C2 is fully charged, and the relay
No current flows through RY, contact RYa becomes 0FF, and the emergency brake is activated.

If any of the air pressure switches fails, for example, the oscillator 10 fails, the output D of the oscillator 10 becomes 0 and the output D of the pneumatic converter 11 becomes 0, as shown in the first half of FIG. The output E and the output F of the differential amplifier 12 are both E and F in the same figure.
It becomes 0 as shown in the first half of . As a result, the output G of the comparator 13 maintains a low level as shown in the first half of FIG. However, capacitor C2 becomes fully charged, the potential on the input side I of full-wave rectifier RE becomes 0 as shown in the first half of I in the same figure, and no current flows through relay RY as shown in the first half of J in the same figure. ,contact
As shown in the first half of Figure 4, RYa is turned off, the emergency brake is activated, and a failsafe is achieved.

Note that if the pneumatic converter 11 fails and its output E becomes 0, and if the differential amplifier 12 fails and its output F becomes 0, the comparator 13
If transistor TR2 fails and its output G becomes a low level, or if transistor TR2 fails and its output H becomes a high level, capacitor C2 becomes fully charged in the same way as above, and becomes an emergency state. The brakes are activated and fail-safe.

Further, for example, if the comparator 13 fails and its output G maintains a high level as shown in the latter half of FIG. As a result, the capacitor C2 becomes low level as shown in the second half of
is completely discharged, and on the input side of the full-wave rectifier RE, the potential I becomes 0 as shown in the second half of Figure 4, and the relay RY becomes 0 as shown in the second half of Figure 4.
It becomes OFF, the emergency brake is activated, and it is a failsafe.

In addition, even if any of the oscillator 10, the pneumatic converter 11, and the differential amplifier 12 fails and the input F of the comparator 13 becomes a DC signal of a constant level higher than the reference value +V1, or the Teton transistor TR2 Even in the case of a failure and the output H is maintained at a low level, the capacitor C2 becomes completely discharged in the same manner as above, the emergency brake is activated, and fail-safe is achieved.

Note that contact RYa (switching element 4) is ON.
If it is a fail-safe to
RYa may be used as a b contact.

[Effect of idea]

As described above, according to the present invention, an oscillator is connected to the pneumatic converter so that the output of the pneumatic converter becomes an AC signal in a non-fail state, and the AC output of the pneumatic converter is If the output of the pneumatic converter is normal, the output of the comparator will be an AC signal, and if the output of the pneumatic converter is abnormal, the output of the comparator will be a DC signal. The configuration is such that the reference value to be given to the comparator is selected and the output of this comparator is supplied to the switching element via the capacitor, so under normal conditions, the AC signal from the comparator is not transmitted to the switching element via the capacitor. This becomes the first state, and in an abnormal state, the output of the comparator becomes a DC signal, so the switching element becomes the second state and can cope with the abnormal state. Moreover, if a failure occurs in either the oscillator, the pneumatic converter, or the comparator, the output of the comparator becomes a DC signal, so this DC signal is blocked by the capacitor and is not supplied to the switching element. , the switching element enters the second state, and fail-safe can be achieved.

[Brief explanation of the drawing]

Fig. 1 is a schematic electrical circuit diagram showing one embodiment of the present invention, Fig. 2 is an operational explanatory diagram showing the output of each part in a non-fail state of the same embodiment, and Fig. 3 is a schematic electrical circuit diagram of a conventional example. The circuit diagram and FIG. 4 are operation explanatory diagrams showing the outputs of each part in a fail state of this embodiment. 4... Switching element, 10... Oscillator, 1
1... Pneumatic converter, 12... Differential amplifier, 13...
...Comparator, C2...Capacitor.

Claims (1)

[Claims for Utility Model Registration] A pneumatic converter that outputs an electrical signal according to air pressure, a comparator that inputs this electrical signal and compares it with a reference value, and a switch that operates based on the output of this comparator. An electric barometric pressure switch for a railway vehicle, comprising: an oscillator connected to the pneumatic converter, an output of the pneumatic converter being an AC signal, and a comparator connected to the pneumatic converter when the reference value is the AC signal. The comparator is configured to output an alternating current signal when the amplitude is within the amplitude of the signal, and output a direct current signal when the amplitude deviates from the amplitude of the alternating current signal, and to cut off the direct current signal on the output side of the comparator. 1. An electric air pressure switch for a railway vehicle, characterized in that a capacitor is connected to the switching element, and the switching element is in a first state when a signal is supplied via the capacitor, and is in a second state when a signal is not supplied.