MXPA96004549A - Circuito de seguri - Google Patents

Abstract

The present invention relates to a safety circuit with a drive device for electrical appliances by means of which the drive device is capable of being operated by means of two key buttons or switch batteries, characterized in that the two key buttons or batteries of switch, characterized in that the two key buttons each have a disconnect contact and a connection contact and act in combination with an associated driving stage, preferably a transistor driven stage with the transistors that the driving stage has two relays, that an astable or multivibrator circuit with an elementary frequency of approximately 1000 Hz for the generation of the two complementary square wave signals is connected to the relays through the contacts so that the relays are dynamically switchable

Description

"SECURITY CIRCUIT" This invention relates to a safety circuit with a drive device for electrical appliances, by means of which the drive device is capable of being operated by means of two key buttons or switch fibers. Many different areas of application must be understood by the term electrical appliances, that is, the invention can be applied to all electrical safety devices with two key buttons or separate electrical switch cells used for protection circuits, such as those used with light grilles or protective doors, for example, with a mechanical plant, emergency supervision, supervision of limit switch, carpets, light curtains and the like. The presses, punching machines, milling machines, lathes or winding devices can be cited as examples of a mechanical plant. In practice and the state of the technology, several designs of safety circuits of the type described above and in fact used in combination with electrical apparatuses or machines are known in which, in the connected state, dangerous conditions exist for operating personnel, in particular, dangerous machine movement. A two-handed action is used to connect to a dangerous condition that ensures that both hands of the operator are occupied and that any possibility to intervene * with any hand in the space where the danger is eminent is discarded. At the same time, it must guarantee that the operator or his legs are in the place where there is no danger for the operator and during the dangerous movement. In connection with this, one battle with the known safety circuits to make sure that any manipulation is discarded by means of two-hand operation. In addition, one struggles to ensure that the safety circuit works perfectly so that only then complete switching at the consumer terminals is possible, that is, switching to the dangerous operating connection and that, on the other hand, if it arises. Any failure within the circuit, it is sure to be able to avoid complete switching.

'The electrical safety circuits known so far either do not meet all the safety criteria or are structured in a complicated way and are costly to build in a way that requires a very high expense and a safety risk is evident in the complexity of the building. The invention is based on the task of creating a security circuit with general application and which is simple and structured clearly meaning therefore low cost but nevertheless fulfills all security criteria including the prevention of any kind of manipulation. To solve this problem, a safety circuit with the features of claim 1 has been proposed. Therefore, the safety circuit essentially comprises two subsets namely a driving stage and an astable or multivibrator circuit, with the properties provided in FIG. claim 1. In an advantageous embodiment of the invention, a capacitor is provided which is dimensioned in such a way that in the equilibrium position, it stores the energy that is required to provide the astable or multivibrator circuit with a voltage within a time of actuation 500 ms maximum of two key buttons. In this regard, it is advantageous if, with the operation of the two key buttons within a driving time of 500 ms, the driving stage is supplied with a voltage V + and V- through the connection contacts of the key buttons and the relays are activated. in the circuit, the capacitor is integrated into the astable or multivibrator circuit.

Preferably, the astable or multivibrator circuit generates square wave signals with a shore slope of up to 10 microseconds, preferably, less than one microsecond, whereby there is an impulse service factor Ten ^ -ratio to tsalida ° e ^ 0 percent to 50 percent. According to a further feature of the invention, a first diode is provided between the first button button and the driving stage and a second diode is provided between the second button button (S2) and the driving stage whereby the diodes block the flow of current to the driving stage when the key buttons are inoperative. Furthermore, in an advantageous extension of the security circuit according to the invention, the way is provided so that the square wave signals from the astable or multivibrator circuit activate the driving stage in such a way that the square wave signals are alternately high and low, so that either the first or the second relay is energized. In accordance with a further feature of the invention, there is provided a way for the astable or multivibrator circuit to be supplied with power through the relay connection contacts if the relays are activated.

Finally, with the security circuit according to the invention, the manner in which two complementary square wave signals persist through similar time intervals and are inversed with respect to each other is provided. A preferred design form of the security circuit according to the invention is shown in the drawing, the structure and function of which will be described below. The security circuit shown in the drawing essentially comprises a driving stage 2 shown in the rectangle marked in the dot-and-dash pattern and an astable or multivibrator circuit which is similarly enclosed in a rectangle of dot and dash lines in the drawing , and which is connected to the driving stage 2 as will be explained in detail below. The driving stage 2 is operated in combination with two key buttons SI and S2 of the driving device, for example, with a two-hand drive not shown in detail. The two buttons Si and S2 of the key must be operated as simultaneously as possible, at least, within the short operating time which is discussed further in greater detail below. The electric voltage V + or V- is supplied to the driving stage 2 through the key buttons SI and S2. The driving stage 2 has two transistors Q1 and Q2 of the PNP type and two transistors Q3 and Q4 of the NPN type. The bases of transistor Q2 of type PNP and transistor Q4, of type NPN are connected to each other by line 3, where two resistors R2 and R4 and two Zener diodes Z2 and Z4 are connected in series. In addition, between the Z2 and Z4 Zener diodes, which are connected with the series aid and its conduction direction from the resistor R4 to the resistor R2, a line 4 is connected, connecting the driving stage 2 with the astable or multivibrator circuit 1 and transmitting a signal 1 which will be further explained in detail below, whereby line 4 is connected in the multivibrator with a line 5 connecting the resistor R6 with the collector of transistor Q5. In addition, the collector of transistor Q2 of PNP type is connected to collector or transistor Q4 of NPN type through a line 6. The emitter of transistor Q4 of type NPN is, on the other hand, connected to the emitter of transistor Q3 of type NPN whose collector is connected to the collector of transistor Ql of PNP type by a line 7. The emitter of transistor Ql of type PNP is also connected to the emitter of transistor Q2 of type PNP. The transistor Ql of the PNP type and the transistor Q3 of the NPN type are also connected through a line 8 which is connected to the bases of the aforementioned transistors Ql and Q3. Two resistors are connected on line 8 between which Zener diodes Zl and Z3 are connected. Between the Zener diodes Zl and Z3, the line 9 is connected, which connects the line 8 in the driving stage 2 with a line 10 in the astable or multivibrator circuit 1, whereby line 10 runs between the resistance Rll and the collector of transistor Q6 of type NPN. The signal 2 that will be explained below is transmitted through line 9. Two combinations of relay-diodes are connected between lines 6 and 7 whereby a diode V4 and a relay K1 are connected on a line 11 whereby the direction of conduction of these diodes runs from the collector of transistor Ql of PNP type towards the collector of transistor Q4 of type NPN. a recovery diode V5 is connected in parallel with the relay Kl whose conduction direction is opposite to the conduction direction of the diode V4. The second relay-diode combination comprises a line 12 where the diode V7 and a relay K2 are connected in series, whereby the diode V7 is connected on the collector side of the PNP transistor Q2 and the relay K2 is connected with the collector side of transistor Q3 of type NPN, and the conduction direction of diode V7 runs from the collector of transistor Q2 of PNP type to the collector of transistor Q3 of type NPN. further, a recovery diode V6 is connected in parallel with the relay K2 whose driving direction runs in opposition to the driving direction of the diode V7. The key button SI, which in this example is equipped with collateral contacts, namely a disconnection contact and a connection contact, is connected to the driving stage via a line 13. Similarly, the button S2 of key that is also equipped with the collateral contacts namely a disconnection contact s2 and a connection contact s2s, is connected to the driving stage through a line 14. On lines 13 and 14, which also flow into the circuit Astable or multivibrator 1, the allo and connection contacts are placed, whereby a VIO diode is connected in series with the switch-off contact and a Vil diode is connected in series with the switch-off contact, whose driving directions they are oriented in opposition. According to this design example, the additional lines 17 and 18 run parallel to lines 13 and 14 which similarly connect the key SI button in one hand and the key button S2 in the other hand with the astable circuit or multivibridator 1. The contacts k2s and kis of connection of the relays K2 and K1 are provided on the lines 17 and 18. In a similar manner, the diodes V9 and VIO are connected in series with the contacts k2s and kis of connection, which in turn they are oriented with their opposite driving directions to each other, so that diodes V9 and VIO on the one hand and diodes VII and V12 on the other hand are oriented with their conduction directions in opposition. The driving stage 2 is connected to the line 13 through a line 21, whereby the line 21 is connected between the emitters of the transistors Q1 and Q2 and type PNP and have a diode VI, whose driving direction is oriented to from the key SI button to the connection line between the emitters of transistors Ql and Q2 of type PNP. Between the driving stage 2 and the line 14, a line 22 is provided which likewise has a diode V8 and is connected between the emitter sides of the NPN type transistors Q3 and Q4 so that the V8 diode has its conduction direction from the emitters of transistors Q3 and Q4 of the NPN type to line 14. The astable or multivibrator circuit has two transistors Q5 and Q6 of NPN type, the base of each being connected between a resistor R5 or R12 and a diode V15 or V14 respectively . The collector of transistor Q5 of type NPN is connected in series with a resistor R6, against which the collector of transistor Q6 of type NPN in series and with resistance Rll is connected. The resistor R6 is connected in parallel with two resistors R7 and R8 and the resistor Rll is connected in parallel with two resistors R9 and RIO. A diode V13 is connected between the resistor R6 and R7 and a diode V16 is connected between the resistors RIO and Rll whereby the conduction direction of the diode V13 runs from the resistor R7 to the resistor R6, and the conduction direction of the diode VI6 runs from the RIO resistance to the Rll resistance. In addition, a capacitor Cl is connected between the resistors R7 and R8 and a capacitor C2 is connected between the resistors R9 and RIO, so that the resistors R8 and R9 are connected in series with the diodes V14 and V15, whose direction of conduction runs in the direction of the bases of transistors Q5 and Q6 of type NPN. Also, a capacitor C3 and a resistor R13 are connected in parallel with the resistor Rll so that the positive plate of the capacitor C3 is oriented on the resistance side Rll and the negative capacitor plate C3 is on the resistance side R13 , and that on the output side it is connected to the emitter of transistor Q6 of NPN type and the resistor R12 is connected in parallel with it.

The way in which the above-described safety circuit operates is essentially the following: First, it should be noted that the safety circuit, in accordance with the example of the described design, is operated with a direct current, if the buttons of buttons SI and S2 of the driving device, for example, a two-hand driving device are not depressed, then, the safety circuit is in its rest condition. Energy is supplied through the closed contacts of the connection, simplified by the so-called ESB (external starting condition) with the feedback circuits known, namely with the connection of the safety circuit with the rest of the machine control system, for example, a metal work machine that can be dangerous. In addition, the astable circuit or multiplexer 1 is supplied with a voltage V- through the relay trip circuit K2o, the diode V1 and the trip contact s2d of the key button S2. The astable or multivibrator circuit 1 is supplied with the voltage V + through the relay klo contact of the relay Kl, the VIO diode and the only act of disconnecting the key SI button. The astabale or multivibrator circuit 1 oscillates in this condition and generates two square wave signals namely, signal 1 and signal 2, which are complementary and inverse with respect to each other and which each persist through the same interval of time. weather. In this constant state, the capacitor C3 acquires the energy or stores it, which is the energy that it requires in order to supply the astable or multivibrator circuit within a maximum activation time of 500 milliseconds for the key buttons SI and S2. If the two push buttons SI and S2 are not operated within this operating time, that is, practically simultaneously, capacitor C3 is discharged prematurely so that the astable or multivibrator circuit no longer supplies the relays K1. and K2, in such a way that the additional operation of the safety circuit will be interrupted. The diodes VI and V8 in this condition, where the key buttons SI and S2 are inoperative, block the flow of the current for the driving stage 2 so that the relays K1 and K2 are not activated. If in this condition the klick contact and the trip of the Kl or K2 relays are not closed, the astable or multivibrator circuit would not work. Since the relays Kl and K2 are restriction relays, a possible contact fault can be detected. By actuating the key buttons SI and S2 within the operating time of 500 milliseconds, the driving stage 2 is supplied with a voltage V + and V- through the switching circuits sis and s2s. Diodes VI and V8 are now polarized in a forward direction. In this condition, the energy stored in capacitor C3 supplies the astable or multivibrator circuit during the interval of the drive time which is a maximum of 500 milliseconds. By operating the key buttons SI and S2 within the maximum operating time of 500 milliseconds, the relays K1 and K2 are activated and supplied to the astable or multivibrator circuit 1 via the diodes V9 and V12 with a voltage. In this way, the square wave signals, the signal 1 and the signal 2 from the astable or multivibrator circuit, control the driving stage 2 in the following manner: In a first state, the signal 1 is raised and the signal 2 is low , by which the transistors Ql and Q4 conduct and the relay kl is activated, so that the contacts of the relay are commutated accordingly. In a second state, the signal 1 is low and the signal 2 is high, so that the transistors Q2 and Q3 lead and the relay K2 is activated so that its contacts are commutated accordingly. If the relays K1 and 2 are activated, then the astable or multivibrator circuit 1 is supplied with power via the relay contacts K1 and K2 of the K1 and K2 relays. In the first state mentioned above, the current flows from Al through the contact sis of the key SI button, the diode VI, the transistor Ql, the diode V4 through the relay Kl to the transistor Q4 and from the transistor Q4 through the diode V8 and the contact s2s of connection of the button S2 of key to Al. In this way, the relay Kl is activated. In the second state mentioned above, the current flows from Al through the contact contact of the button or button, the diode VI to the transistor Q2 and from the transistor Q2 through the diode V7 through the relay K2 and from there through the transistor Q3 to the diode V8, in order to flow towards A2 through the contact s2s of connection of the button S2 of key. In this state, relay K2 is activated. The frequency of the astable circuit or multivibrator 1 is preferably 1000 Hz and consequently changes the state of the signals, signal 1 and signal 2 every 0.5 millisecond. Limited by the decay time of the relays Kl and K2 and the magnetic energy stored in the respective relay coil that maintains the flow of the mutual induction current within the time intervals of trip or drive through the recovery diode V5 for relay Kl, and recovery diode V6 for relay K2, both relays Kl and K2 remain activated. This condition is maintained until the key buttons SI and S2 are released. Now, diodes VI and V8 block the flow of the current and the driving stage 2 is no longer supplied with a voltage. The relays Kl and K2 are released so that the neutral condition of the equipment and the safety circuit is reached. Due to different tolerances, either transistor Q5 or transistor Q6 is controlled by the stable circuit or by multivibrator 1 at the time of connection. For the case where the transistor Q6 is controlled, the collector of the transistor Q6 is at a low potential that corresponds to the signal 2. Then, a charge current flows which is defined by the resistor R9 through the capacitor C2. The base of the transistor is first at the low potential so that the transistor Q5 is blocked. Because of this, the collector of transistor Q5 is at a high potential corresponding to signal 1. As a consequence of the charging current flowing through capacitor C2, the potential at the base of transistor Q5 rises until it is capacitance the transistor. Then the signal 1 decreases to a low potential and simultaneously a charge current flows through the capacitor Cl which is defined by the resistance R8. The base of the transistor then drops or decreases again towards a low potential and blocks the transistor Q6, whereby the signal 2 goes to a high potential. This process works cyclically. With the proviso that R9 X C2 = R8 X Cl, signal 1 advances with respect to signal 2 in such a way that the high and low phases continue through the same time interval and are inversely oriented with respect to each other . The diodes V13, V14, V15 and V16 which are in the safety circuit described above, are used to accelerate the transit time of the signals 1 and 2.

The operating points are indicated by resistors R5 and R12. From the following consideration of faults, additional features and functions of the security circuit according to the invention will become apparent. This failure test shows, first and foremost, that all conceivable failures of the key buttons until the start of ESB (external start condition) of the external machine control system are recognized, and in each case switching is prevented complete The dangerous movement from which it is necessary to protect itself is uncoupled through two non-designated points of departure of the safety equipment, both the redundant starting points and the context connection circuits can also be developed in the contact disconnection circuits. Fault test 1 S connection contact - The multivibrator operates in a constant position. No 1.) YES: more line disconnection when activated SI 2 S connection contact - Short circuit 2.) YES: connected 3 S disconnection contact - The multivibrator does not work in a constant position.

YES: line disconnection (not less) 4 S disconnection contact - Short circuit when activated 4.) YES: connected 5 S connection contact The multivibrator operates in a constant position. No 5.) S2: line disconnection less when operated S2 6 S connection contact Short circuit 6.) S2: connected 7 S disconnection contact The multivibrator does not work in a constant position S2: line disconnection (no more) 8 S disconnection contact Short circuit when activated) S2: connected Q B Ql blocked, there is no base driver for Q3. K2 no 9. ) connects. There is not Ql: disconnected output on the channel and channel 2 Q B - C Q3 and Q4 are permanently trained. Short circuit through Q2 and Q5.

. ) Kl and K2 do not know Ql: connection connect. There is no exit on channel 1 and channel 2 1 Q B Ql blocked (see 11. ) the failure 9) Ql: disconnection B - B Ql blocked (see fault 9) 12 Ql: connection 1 Q C Q blocked (see fault 9) 13.) Ql: disconnect 1 Q B - C Ql drive, short circuit through 14. ) of Q2 and Q3. Kl no Ql: connection is connected. There is no exit on channel 1 and on channel 2 Q B Q2 blocked. Kl does not connect. There is not Q2: output disconnection on channel 1 and channel 2 , 1 Q B - C emitter-collector of connected Q2. Short 16. circuit through Q2: connection Q3. Kl does not connect. There is no output on the channel or channel 2 1 QB Q2 blocked (see fault 15) 17.) Q2: disconnection 1 QB - B Q2 blocked (see fault 15) 18.) Q2: connection 1 QC Q2 blocked (see failure 15) 19.) Q2: disconnection 2 QB - C Q2 conducts, short circuit through Q2 and Q3. Kl no . ) connects. There is not Q2: output connection on channel 1 and channel 2 2 Q B Q3 blocked. Kl does not connect. There is not 21. ) output on channel Q3, connection 1 and on channel 2 Q B C emitter-collector of connected Q3. Short circuit through 22.) of Q2. Kl do not know Q3: connection connects. There is no output on channel 1 and channel 2 2 QB Q3 blocked (see fault 21) 23.) Q3: disconnection 2 QB -B Q3 blocked (see fault 21) 24.) Q3: connection QC Q3 blocked ( see fault 21) 25.) Q3: disconnection 2 QB - C Q3 conducts, short circuit through Q2 and Q3. Kl no 26. ) connects. There is no Q3, connection output on channel 1 and on channel 2 2 Q B Q4 blocked. K2 does not connect. There is not 27. output on channel Q4: disconnect 1 and on channel 2 2 Q B - C emitter-collector of connected Q4. Short circuit to 28. ) through Q5. K2 no Q4: connection is connected. There is no exit on channel 1 and on channel 2 2 Q B Q4 blocked (see fault 27) 29.) Q4: disconnection 3 Q B - B Q4 blocked (see fault 27) Q4: connection 3 Q C Q4 blocked (see fault 27) Q4: disconnection 3 Q B - C Q4 drives, short circuit through Q4 and Q5. K2 does not connect. There is not Q4: output connection on channel 1 and on channel 2 3 Q B Q5 blocked. Kl does not connect. There is not Q5, disconnection output on channel 1 and channel 2 3 Q B - C emitter-collector of Q5 connected. Short circuit through Q4. K2 does not know 34. ) connect. There is no Q5: connection output on channel 1 and on channel 2 3 Q B Q5 blocked (see fault 33) 35.) Q5: disconnection 3 Q B - B Q5 blocked (see fault 33) 36.) Q5: connection 3 Q C Q5 blocked (see fault 33) 37. Q5: disconnection 3 Q B - C Q5 drives, short circuits through Q4 and Q5. K2 no 38. connects. There is no Q5: connection output on channel 1 and on channel 2 3 Q B Q6 blocked, no base drive for Q5. K2 does not know 39. ) connect. None Q6: dexonexion output on channel 1 and on channel 2 4 Q B - C Q2 and Q5 permanently trained. Short circuit through Q3 and Q4. 40.) K2 does not connect. Q6: connection There is no output on channel 1 and channel 2 4 Q B Q6 blocked (see fault 39) 41.) Q6: disconnection 4 Q B - B Q6 blocked (see fault 39) Q6: connection 4 Q C Q6 blocked (see fault 39) Q6: disconnection 4 Q B - C Q6 drives, short circuit through Q4 and Q5. K2 no connection connects. There is no Q6: connection output on channel 1 and channel 2. 4 V high resistance V9 blocked. Kl does not connect. There is no exit on channel 1 and on V9: channel 2 4 V low resistance Short circuit through Q4 - VIO - V9 - Q3. K2 is not connected. There is not V9: output on channel 1 and channel 2 4 V VIO high resistance blocked. Kl is not connected. No exit VIO: on channel 1 and on channel 2 4 V low resistance Short circuit through Q2 - V9 - VIO - Q5. , Kl does not connect. There is not I SAW exit on channel 1 and on channel 2 4 V high resistance V blocked. K2 does not connect, there is no output. on channel 1 and on Vil canal 2 V low resistance Short circuit through, from Q4 - V12 - Vil - Q3.

Vil: K2 does not connect. There is no exit on channel 1 and on channel 2 V high resistance V12 blocked, K2 does not 51 connects. No exit V12 on channel 1 and on channel 2 V low resistance Short circuit through Q2 - VIL - V12 - Q5. Kl 52. does not connect. There is no V12 output on channel 1 and on channel 2

Claims (10)

R E I V I N D I C A C I O N E S;

1. A safety circuit with a drive device for electrical appliances by means of which the drive device is capable of being operated by means of two key buttons or switch batteries, characterized in that the two key buttons each have a disconnect contact (sló, s2o) and a connection contact (sis, s2s) and act in combination with an associated driving stage (2), preferably a transistor-driven stage with the transistors (Q1, Q2, Q3, Q4), which the The driving stage has two relays (Kl, K2), that an astable or multivibrator circuit (1) with an elementary frequency of approximately 1000 Hz for the generation of the two complementary square wave signals is connected to the relays (Kl, K2) to through the contacts (kl, k2) so that the relays (Kl, K2) are dynamically switchable.

2. A safety circuit according to claim 1, characterized in that a capacitor (C3) is provided which is dimensioned in such a way that in the constant state, it stores the energy that is required to provide the astable or multivibrator circuit (1) with a voltage within a maximum activation time of 500 ms of the two key buttons (SI, S2).

3. A safety circuit according to claim 2, characterized in that with the activation of the two buttons (SI, S2) within a maximum operating time of 500 ms, the driving stage is provided with a voltage V + and V- a through the connection contacts (sis, s2s) of the key buttons (SI, S2) and the relays are activated.

4. A safety circuit according to claim 2 or 3, characterized in that the capacitor (C3) is integrated in the astable or multivibrator circuit (1) •

5. A safety circuit according to any of claims 1 to 4, characterized in that the astable or multivibrator circuit (1) has a pulse service factor Ten to 50 percent to 50 percent .

6. A security circuit according to any of claims 1 to 5, characterized in that the astable or multivibrator circuit (1) generates square wave signals (Signal 1, Signal 2) with a shore inclination of up to 10 microseconds, of preference, less than 1 microsecond.

7. A safety circuit according to any of claims 1 to 6, characterized in that a first diode (VI) is provided between the first key button (SI) and the driving stage (2), and a second diode is provided. (V8) between the second button (S2) of the key and the driving stage (2) by means of which the diodes (VI, V8) block the flow of the current to the driving stage when the key buttons are inoperative. A security circuit according to any of claims 1 to 7, characterized in that the square wave signals (Signal 1, Signal 2) from the astable or multivibrator circuit (1) activate or trigger the driving stage in such a way that the square wave signals (Signal 1, Signal 2) are alternately raised and lowered so that either the first relay (Kl) or the second relay (K2) is energized. A safety circuit according to any of claims 1 to 8, characterized in that the astable or multivibrator circuit (1) is supplied with power through the relay connection contacts (Kl, K2) and the relays are activated (Kl, K2). A security circuit according to any of claims 1 to 9, characterized in that the two complementary square wave signals (Signal 1, Signal 2) persist through similar time intervals and are inversed one with respect to the other.