JPH0124479Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a control circuit for a cover switch that controls the operation and stopping of the movable part in conjunction with the opening and closing of a maintenance cover for the movable part of the machine.

Moving parts of machines are usually covered to prevent them from being touched to prevent danger, but moving parts of machines that transport goods, such as ticket conveyance devices in automatic ticket gates, can become clogged with goods. They are often equipped with a maintenance cover that can be opened and closed in order to remove jammed items and restore normal operation in the event that normal operation is interrupted. In order to prevent injuries caused by unexpectedly restarting stopped movable parts during maintenance work, a cover switch is installed that outputs condition signals for stopping and operating movable parts in conjunction with opening and closing of the maintenance cover. is widely used. On the other hand, it is necessary to confirm whether normal operation will be resumed at the end of the normalization work.

Conventionally, in order to meet this requirement, the maintenance cover (hereinafter simply referred to as the cover) was left open.
Press down the contact piece of the cover switch from the normally closed contact to the normally open contact with your finger, apply adhesive tape, etc. to hold the cover switch in the same state as when the cover is open, and then operate the movable parts. made possible. When using this method, the cover switch has a repulsive force, so if it is not properly held down with adhesive tape, etc., the cover switch will return from a normally open contact to a normally closed contact, and the movable part will automatically stop. There are also disadvantages in that the adhesive tape remains dirty due to adhesion of adhesive and dust.

Another conventional method is to provide a toggle switch separate from the cover switch and operate it after opening the cover to obtain the same state as when the cover is closed. However, with this method, if you turn on the toggle switch and forget to turn it off at the end of normal operation and close the cover, the movable parts will not stop operating when you open the cover again for maintenance. ,
The drawback was that it was a very dangerous situation.

Therefore, this invention was developed for machines that have moving parts that pose a risk of injury if touched during maintenance. When the cover is opened, the moving parts covered by the cover automatically stop operating, and a push button switch is activated. By pressing the button, a test run can be performed automatically with the cover open, and after a successful test run, simply closing the cover will restore the original normal state (i.e., the state in which operation will be stopped when the cover is opened again). ) The object of the present invention is to provide a cover switch control circuit that can be restored to

Next, an embodiment of this invention will be described based on the drawings.

S ₁ is a cover switch, and when a cover (not shown) that covers moving parts of the machine that are dangerous to touch is closed, the contact piece b, whose one end is pivotally attached to the common contact C, is moved by the cover. Normally open contact NO
When the cover is opened, the spring of the contact piece b returns to contact with the normally closed contact NC. The normally open contact NO is connected to the output circuit I, and the common contact C is connected to the first power source _PS1 . Output circuit I is the cover switch _S1
It detects that the contact piece b has left the normally open contact NO, that is, that the cover has been opened, and outputs a cover open detection signal as one of the conditions for stopping the mechanical movable part, as shown in the figure. In this embodiment, the normally open contact NO of the cover switch is connected to the first contact of the output circuit.
By connecting the first power supply PS ₁ to the input terminal and the second input terminal, the output circuit I
A cover closed detection signal α ₀ is output to the output terminal of the sensor, and since a predetermined potential difference occurs between the two inputs when the cover is open, a cover open detection signal α ₁ is output to the output terminal.

Further, the normally closed contact NC of the cover switch _S1 is connected to a second power supply having a higher voltage than the first power supply _PS1 .
A pushbutton switch S ₂ is connected to PS ₂ and is provided between the normally closed contact and the second power source. This push button switch _S2 is installed as a so-called hidden switch inside the machine so that it can be operated only when the cover is opened, and is normally open and turned ON only when the button is pressed by maintenance personnel.

In this invention, the push button switch
A relay A is provided between S ₂ and the second power supply PS ₂ , and the first normally open contact a ₁ of the relay is connected to the push button switch S ₂
The second normally open contact _A2 of the relay is connected to the parallel circuit _C1 provided in parallel with the output circuit I and the first power supply.
PS ₁ and the short circuit c ₂ provided in parallel with the cover switch S ₁ .

Next, the operation of the cover switch control circuit with the above configuration will be explained. First, when the cover is closed, each component of the control circuit is in the state shown in the attached drawing, and the circuits N, J, and H are in the state shown in the attached drawing. , G is formed, and the potential difference between N and T disappears, so
A cover closing detection signal α ₀ is output from the output circuit I. Therefore, the mechanical movable parts inside the cover are operated when the other operating conditions are fulfilled. On the other hand, if a malfunction occurs, such as jamming of a conveyed article in a moving part of the machine, when the cover is opened to normalize the machine, contact b of cover switch S ₁ switches to the normally open contact NO. Since the circuit moves from to the normally closed contact NC, the circuit Nut is no longer configured and the potential difference between Nu and To increases, so the cover open detection signal α ₁ is output from the output circuit I, and the machine body The safety function is activated and the mechanical movable parts are automatically stopped.

After normalization work is completed, such as removing objects stuck in the moving parts of the machine after it has stopped or repairing malfunctioning parts, the cover is opened to see if the machine will restart normally. When performing a trial run in this state, press down the push button switch _S2 . This reduction forms circuits A, B, C, D, E, H, and G, so that current flows through relay A, and the two normally open contacts a ₁ and a ₂ of relay A are closed.
Since the parallel circuit c ₁ is closed by the first normally open contact a ₁ ,
Even when the finger pressing the push button switch S ₂ is released, the normally open contacts a ₁ and a ₂ remain closed. Also,
Normally open contact A ₂ closes short circuit C ₂ , and circuit N,
Since current flows through I, H, and G, the output circuit I is in the same state as when the cover is closed, and outputs the cover closing detection signal α ₀ . Therefore, a trial run can be performed with the cover open.

After completing the normalization work due to the successful trial run,
When the cover is closed again, the contact piece b of the cover switch _S1 moves from the normally closed contact NC to the normally open contact NO again, configuring the circuit N, J, H, G, and at the same time, the relay A is connected. When the current stops flowing, the contact
a ₁ and a ₂ are restored, and the control circuit returns to the state shown. Therefore, the mechanical movable parts can operate normally, and are automatically stopped when the cover is opened again.

Needless to say, if the normalization work has been carried out reliably, the same effect can be obtained even if the cover is closed without pressing the push button switch for a trial run.

As the output circuit I, any detection circuit that detects and outputs changes in potential difference and current that occur when the cover is opened can be used.

As mentioned above, since the cover switch control circuit according to this invention has the configuration described in the claims for utility model registration, firstly, when the cover is opened, the output circuit outputs a cover open detection signal, so that the machine cannot move. section will be automatically stopped. Also, when the pushbutton switch is pressed, the relay operates and its second normally open contact creates the same condition as closing the cover, and the first normally open contact closes the parallel circuit of the pushbutton switch. To perform automatic operation (trial run) with the cover open, all you need to do is press the push button switch once.

Second, the relay continues to operate until the cover is closed again, and when the cover is closed, the cover switch is actuated, deactivating the relay, and resetting its two contacts, so that the control circuitry does not operate before the cover is opened. The state will be restored. In other words, there is no need to remember that the pushbutton switch was operated.
When the cover is closed, it automatically returns to its original state, and when the cover is opened again, the movable parts are automatically stopped. Therefore, there is no need to hold down the push button switch with adhesive tape or the like as in the past, and there is no need for the adhesive tape to peel off midway and stop the movable part, and there is no need to forget to operate it as is the case when using a toggle switch. According to this invention, high safety is guaranteed at the start of normalization work and during the work.

Thirdly, the circuit for realizing the above-mentioned first task ease and safety can be made to have a simple configuration.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of this invention. S ₁ ...Cover switch, I...Output circuit, PS ₁
...First power supply, S ₂ ...Push button switch, PS ₂ ...
...Second power supply, A...Relay, c ₁ ...Parallel circuit, a ₁
...Relay first normally open contact, c ₂ ...Short circuit, a ₂
...The second normally open contact of the relay.

Claims (1)

[Scope of utility model registration request] The cover is opened for the normally open contact of a cover switch whose contact piece moves between a normally open contact and a normally closed contact in conjunction with the opening and closing of a maintenance cover that covers the moving parts of the machine to prevent danger. an output circuit for outputting a cover open detection signal when the cover switch is open; the common contact of the cover switch is connected to a first power source; the normally closed contact is provided so that it can be operated manually only when the cover is opened; Pushbutton switches each having one end connected to a second power supply having a higher voltage than the first power supply are connected, and a relay is provided between the pushbutton switch and the second power supply, and the first normally open contact and the first normally open contact of the relay are connected. A cover switch control circuit comprising two normally open contacts inserted into a parallel circuit connected in parallel to the push button switch and a short circuit provided between the output circuit and the first power source.